The Regenexx blog has a very interesting article on knee plica surgeries. Knee plicas refer to collisions between the knee cap (patella) and the nearby synovial membrane, which surrounds the joint. The pinching of the synovial membrane irritates it and generates swelling and pain. The common surgical procedure to treat knee plica is to extirpate the irritated synovial membrane. Centeno points out that this portion of the synovial membrane houses a robust stem cell population that helps heal knee problems. Therefore, this procedure might not be the best choice for knee plica. Centeno suggests that the knee is not aligned properly and that realignment of the knee cap could solve the problem without surgery. Read his blog post here and see what you think.
The inimitable Wesley Smith has blogged about a remarkable child who was born without several portions of his brain. This little boy, Chase Britton, was born prematurely. He had a MRI scan at the age of one, and this scan showed that Chase was completely missing his cerebellum, and his pons. The cerebellum is a small lobe at the back of the brain that underlies the occipital and temporal lobes of the cerebral cortex. The cerebellum accounts for approximately 10% of the brain’s volume, but it contains over 50% of the total number of neurons in the brain. The cerebellum has several functions: 1) Maintenance of balance and posture; 2) Coordination of voluntary movements; 3) Motor learning; and 4) Cognitive functions.
Those small postural adjustments that help us maintain balance are all mediated by the cerebellum. It does this by means of input from receptors in the inner ear (vestibular receptors) and in the joints that tell your brain about the orientation of your body. Consequently, patients with damage to the cerebellum suffer from balance problems. Most movements result from different muscle groups acting together in a temporally coordinated fashion, and the cerebellum coordinates the timing and force of these different muscle groups to produce fluid limb or body movements. The cerebellum also plays a major role in adapting and fine-tuning motor movements in order to make accurate movements through a trial-and-error process. For example learning to hit a baseball, shooting a basketball, slapping a hockey puck or other types of fine motor processes. Finally, the cerebellum is involved in certain cognitive functions, especially those that require motor skills, for example, language acquisition.
The pons is a portion of the brain that lies just in front of the cerebellum. The pons contains many “vital centers.” Vital centers are clusters of neurons that control vital bodily functions such as breathing, heart beat, and other such functions.
Chase has forced neurologists to rethink how the brain works or how the brain rewires itself in response to damage or developmental abnormalities. From the story:
But instead of being unable to carry out tasks like sitting up or crawling, Chase has forced experts to rethink how the brain functions. His mother Heather Britton told AOL News: ‘We call him the Little Gremlin. He loves to play tricks on people. His goal in life is to make people smile. ‘No one had ever seen it before. And then we’d go to the neurologists and they’d say, “that’s impossible, he has the MRI of a vegetable”.’ Dr Adre du Plessis, chief of Foetal and Transitional Medicine at the Children’s National Medical Center in Washington D.C., told WGRZ: ‘There are some very bright, specialised people across the country and in Europe that have put their minds to this dilemma and are continuing to do so, and we haven’t come up with an answer.
This boy is disabled, but he is not a vegetable. If you do not believe me, see this video of him learning to walk here. However, in places like Holland, Chase would have been exterminated under the Groningen Protocol. According to the Groningen Protocol, Dutch doctors can euthanize infants with terminal and seriously disabling conditions. In Belgium too, disabled babies are murdered, and in most countries, Chase would have been done in. Even though his is not, Chase would have been classified as an “anencephalic” baby. Anencephalic babies are born without the tops of their heads and are missing their cerebral cortex. They have a brain stem and their hearts are still beating but there is no indication that they can feel pain, beyond simple reflexes. The majority of anencephalic babies are born dead (stillborn), and about one third of them live a few hours to a few days. In very rare cases, they will live a few weeks up to a few months. Anencephalic babies are also born blind, deaf, unconscious, and unable to feel pain. They still react with spinal or brainstem reactions to stimuli. They are typically given comfort care until death so that a peaceful environment for the parents, with support from chaplains, counselors, and hospital staff.
Anencephalic babies are considered a good source of organs for neonatal transplantation. The current Uniform Declaration of Death Act (UDDA) requires brain death and irreversible cessation of heart/lung function prior to organ donation. This prevents organ donation from living donors who might have some reversibility in their brain function. Unfortunately, many organs from anencephalic babies may not be usable as a result of damage from a lack of oxygen. With the shortage of fetal or neonatal organs for transplant, some have argued that anencephaly should be the exception to the UDDA requirements. However, the general consensus is that it is unethical to harvest organs from an anencephalic babies until they are “dead.”
Now, according to Smith, programs to procure organs from anencephalic babies often receive organs from babies that are not anencephalic, but from children who are disabled. Listen to these words from Smith’s excellent book, The Culture of Death: The Assault on Medical Ethics in America:
In 1988, Loma Linda University in California created an organ procurement protocol to use anencephalic babies as organ donors in which physicians from around the country were asked to transfer, with parental permission, qualified infants to the Loma Linda University Medical Center where the procurement would take place. The program only lasted eight months before it had to be suspended, in part because of the inability of Loma Linda doctors to procure usable organs in thirteen attempts. However, the primary reason for shutting down the initiative was that physicians referred non-anencephalic, disabled babies to Loma Linda for organ procurement.
Dr. Shewmon, USC bioethicist and law professor Alexander M. Capron and others, writing in the Journal of the American Medical Association described what happened:
[T]he experience at transplantation referral centers indicates that enthusiasm for using anencephalics does indeed quickly extend to other categories of dying infants. As a result of the national interest in Loma Linda’s protocol, for example, that institution received from ‘good’ physicians several referrals of infants with less severe anomalies for organ donation, such as ‘babies born with an abnormal amount of fluid around the brain or those born without kidneys but with a normal brain.’ Moreover, the referring physicians ‘couldn’t understand the difference’ between such newborns and anencephalics.” Joyce Peabody, MD, chief of neonatology there and primary drafter of the protocol, deserves much credit for her courageously candid statement: ‘I have become educated by the experience. … The slippery slope is real’ (D. Alan Shewmon, et al, “The Use of Anencephalic Infants as Organ Sources: A Critique,” Journal of the American Medical Association, Vol. 261, p. 1775).
Calling Chase Britton a vegetable is the height of absurdity and cruelty. He is a human being; a disabled one, but a human person. Thank God that his parents did not condemn him to death because of his disability. His perseverance is a testimony to his human spirit.
Brian Derby from the University of Manchester is using inkjet technology to distribute cells onto scaffolds that are shaped as a particular organ. Inkjet and laserjet technologies can build three-dimensional scaffolds that are coated with cells that will grow into the scaffold, assume its shape and degrade the scaffold, leaving only the tissue in its place.
This type of technology, which involves the simultaneous placement of biodegradable scaffold and cells in a three-dimensional structure that resembles that of an organ is called additive manufacture and it might very well be the future of replacement organ production. Additive manufacture recreates the biological structure in a three-dimensional, digital image, from which two-dimensional, digital slices are taken and fashioned one layer at a time. The summation of all the digital slices eventually produces a three-dimensional structure.
Inkjet technology dispenses the material that makes the scaffold in very small droplets that quickly solidify. The materials is loaded into an actual inkjet printer cartridge that is sprayed onto the surface. More droplets are placed on top of previous droplets in a very specific pattern and this repetitive distribution of droplets develop into a pattern that is very complex and forms a scaffold that nicely mimics the conditions inside the body. The scaffold also provides a surface the for cells to adhere, grow and thrive. The scaffold and its internal structure control the behavior and maintain the health of the cells embedded in the scaffold. This method of distributing cells onto a surface through a printer is called “bioprinting.”
In his article, published in the journal Science, Derby examines experiments in which porous structures are made by means of bioprinting. Bioprinting uses inkjet and laserjet technologies to distribute cells or molecules onto a surface in a desired pattern. In the case of porous structures, cells interweave throughout the scaffold and such cell-encrusted scaffolds can be placed in the body to encourage cell growth. Depending on the composition of the scaffold and the cells embedded in it, the scaffold can become a part of the body or the cells will dissolve it. Such a treatment can help heal patients with particular injuries such as cavity wounds.
Bioprinted cells can also be deposited onto scaffolds with various other chemicals, such as hormones, growth factors, or small molecules that influence the behavior of the cells. The inclusion of such molecules with the scaffold can coax cells to differentiate into distinct cell types, such as, for example, bone- or cartilage-producing cells.
Cells do suffer some damage during bioprinting, and the rule of thumb is the more energy is used to deposit the cells onto the scaffold, the lower the viability of the cells after bioprinting. To deposit and pattern cells in a scaffold there are three techniques that are used: inkjet printing, microextrusion, which is also known as filament plotting, and laser forward transfer. Bioprinting has probably the highest viability rates, and that has come after the techniques have been precisely worked out to ensure a minimum of damage. Microextrusion shows extremely variable rates of cell survival after the cells are deposited. Laser forward transfer suffers from the need for higher energy lasers to more precisely and efficiently deposit the cells, but this same higher energy kills off the cells.
Even though this technology has come a long way, it has a way to go before it is ready for the clinic. Scaffolds are being used in clinical trials, but scaffold synthesis suffers from inconsistency, and until a consistent high-quality is delivered, scaffold production will not be ready for commercial production.
Despite these caveats, there have been some successes. For example, D’Lima and others used an solution of chemicals in water (poly(ethylene glycol) dimethacrylate to be exact) that also contained cartilage-making cells (chondrocytes). They printed this suspension a bone defect in a cultured bone and then used a chemical not unlike what dentists use to harden tooth plastic called a photoinitiator. Such chemicals crosslink and bond together in response to particular wavelengths of light, and D’Lima used light to crosslink the chemicals to make a wet gel that contained the cells. After several days, this printed structure appeared to have integrated into the surrounding tissue. This experiment demonstrates that this technology is at least feasible. The hanging issue is the toxicity of the photoinitiator chemicals to cells (X. Cui, et al Tissue Eng. A 18, 1304 (2012). However, this has been studied, and it turns out the susceptibility to these chemicals is very cell type-specific. Thus, picking the right photoinitiator could potentially make this technique rather safe (see C. G. Williams, et al Biomaterials 26,1211 2005).
Scaffolds, however, can also be used to make external tissues, for example, skin patches. Derby is working with ear, nose, and throat surgeons at the Manchester Royal Infirmary. His goal is to use bioprinting to make patches that can be implanted into the inside of the nose or throat.
Derby explains: “It is very difficult to transplant even a small patch of tissue to repair the inside of the nose or mouth. Current practice, to transplant the patient’s skin to these areas, is regarded as unsatisfactory because they transplants do not possess mucous generating cells or salivary glands. We are working on techniques to print sheets of cells that are suitable for implantation in the mouth and nose.”
Derby hopes that someday bioprinting can be used to grow tumors in realistic cultures that will make superior models for drug testing and drug development.
Pluripotent stem cells have the ability to differentiate into a whole host of adult cell types. Unfortunately this ability to differentiate into any adult cell type also comes with it the tendency to form tumors. Controlling stem cell differentiation requires that you give a little “push” in the right direction. What is the nature of that push? It varies from stem cell to stem cell and it also depends on what type of cell you want you stem cells to make. Therefore, pluripotent stem cell differentiation is sometimes a matter of art as much as a matter of science.
A research group at Stanford University School of Medicine have designed an experimental protocol that uses the signals in the body to direct the differentiation of stem cells to a desired end.
Stanford University professor Michael Longaker, who is also the director of the Institute for Stem Cell Biology and Regenerative Medicine at Stanford University, explained it this way: “Before we can use these cells, we have to differentiate or ‘coach,’ them down a specific developmental pathway.” Longaker continued: “But there’s always a question as to exactly how to do that, and how many developmental doors we have to close before we can use the cells. In this study, we found that, with appropriate environmental cues, we could let the body do the work.”
Allowing the patient’s body to direct differentiation of pluripotent stem cells could potentially speed approval of stem cell-based treatments by the US Food and Drug Administration (FDA). If Longeker’s protocol pans out, it could eliminate long period of extended laboratory manipulation in order to force stem cells to differentiate into the desired cell type.
“Once we identify the key proteins and signals coaching the tissue within the body, we can try to mimic then when we use the stem cells,” said Longaker. “Just as the shape of water is determined by its container, cells respond to external cues. For example, in the future, if you want to replace a failing liver, you could put cells in a scaffold or microenvironment that strongly promotes liver cell differentiation and place the cell-seeded scaffold into the liver to let them differentiate in the optimal macroenvironment.”
Longaker does not work on liver, but bone. As a pedatric plastic and reconstructive surgeon who specializes in craniofacial malformations, finding ways to coax pluripotent stem cells to make bone is his research Holy Grail. “Imagin being able to treat children and adults who require craniofacial skeletal reconstruction, not with surgery, but with stem cells,” opined Longaker.
In this experiment, Longaker and his colleagues removed a four-millimeter circle of bone taken from the skulls of anesthetized mice and implanted a tiny, artificial scaffold coated with a bone-promoting protein called BMP-2 (bone morphogen protein-2) that was seeded with one million human pluripotent stem cells.
According to Longaker, these implants formed bone and repaired the defect in the skulls of the mice even the original stem cells were not differentiated when added to the wound. These human stem cells made human bone that was then replaced by mouse bone as time progressed. This shows that the repair was physiologically normal.
This bone growth was stimulated by the presence of BMP-2 and the microenvironment that induced the stem cells to differentiate into bone-making cells that made normal bone.
In this experiment, Longaker and his group used human embryonic stem cells and induced pluripotent stem cells and both stem types seemed to work equally well at repairing the skull defect.
Teratomas (tumors made by pluripotent stem cells) were observed but only rarely (two of the 42 animals that received the stem cell implants developed tumors). Interestingly, the few teratomas that formed developed in two laboratory animals that received embryonic stem cell implants and not induced pluripotent stem cell implants. This is surprising, since most stem cells researchers consider induced pluripotent stem cells to be more tumorigenic than embryonic stem cells. Standard tests of these stem cells (implantation under the kidneys of immunodeficient mice) showed that they did produce teratomas under these conditions.
Longaker commented: “We still have work to do to completely eliminate teratoma formation, but we are highly encouraged.” Longaker also thinks that by combining this technique with other strategies, he and his group might be able to completely prevent teratoma formation. For example, including other cell types that can act as shepherds for the stem cells as they differentiate into the desired cell type can also increase differentiation into a desired cell type.
Longaker said, “I want to see how broadly applicable this technique may be.” He was referring to tissues that do not heal well. For example, cartilage heals very poorly if at all. Longaker wonders if you could “add some cells that can form replacement tissue in this macroenvironment while you’re already looking at the joint.”
A study from the laboratory of Armand Keating at the University of Toronto and Princess Margaret Hospital has compared the ability of umbilical cord stem cells and bone marrow stem cells to repair the hearts of laboratory animals after a heart attack. The umbilical cord stem cells showed a clear superiority to bone marrow stem cells when it came to repairing heart muscle.
Keating used human umbilical cord perivascular cells (HUCPVCs) for his experiment, and these cells are widely regarded as a form of umbilical cord mesenchymal stem cell that surround the umbilical cord blood vessels.
Transplantation of cells from either bone marrow or umbilical cord into the heart soon after a heart attack improved the function and structure of the heart. However, functional measurements showed that the HUCPVCs were twice as effective as bone marrow stem cells at repairing the heart muscle.
Keating added: “We are hoping that this translates into fewer people developing complications of heart failure because their muscle function after a heart attack is better.”
In addition to further pre-clinical tests, Keating and his research team hope to initiate clinical trials with human patients within 12-18 months. Keating is also interested in testing the ability of umbilical cord stem cells to heal the hearts of those cancer patients who have experienced heart damage as a result of chemotherapy. In such patients, chemotherapy rids their bodies of cancer, but the cure is worse than the cancer, since the drugs also leave the patients with a severely damaged heart. Such stem cell transplantations could potentially strengthen the hearts of these patients, and give them a new lease on life. My own mother died from congestive heart failure as a result of an experimental arsenic treatment that killed her heart muscle. My mother suffered from chronic myelogenous disease and the arsenic was meant to kill off all the rogue cells in her bone marrow, but instead it killed her heart. If such a stem treatment were available then, my mother might still be with me.
There are over 250 clinical trials with mesenchymal stem cells to date to treat conditions ranging from Crohn’s disease to neurological conditions. Also, a recent meta-analysis has established the safety of mesenchymal stem cell treatments for several different conditions (see Lalu MM, McIntyre L, Pugliese C, Fergusson D, Winston BW, et al. (2012) Safety of Cell Therapy with Mesenchymal Stromal Cells (SafeCell): A Systematic Review and Meta-Analysis of Clinical Trials. PLoS ONE 7(10): e47559. doi:10.1371/journal.pone.0047559).
Mesenchymal stem cells (MSCs) have the ability to home to growing tumors, and for this reason, many researchers have examined the possibility of using MSCs to treat various types of cancers. However, there is a genuine safety concern with using MSCs in cancer patients, because in laboratory animals, MSCs can form blood vessels that help tumors grow and spread. Consider the following publications:
1. Klopp AH, Gupta A, Spaeth E, Andreeff M, Marini F 3rd (2011) Concise review: Dissecting a discrepancy in the literature: do mesenchymal stem cells support or suppress tumor growth? Stem Cells 29: 11–19.
2. Kidd S, Spaeth E, Klopp A, Andreeff M, Hall B, et al. (2008) The (in) auspicious role of mesenchymal stromal cells in cancer: be it friend or foe. Cytotherapy 10: 657–667.
3. Coffelt SB, Marini FC, Watson K, Zwezdaryk KJ, Dembinski JL, et al. (2009) The pro-inflammatory peptide LL-37 promotes ovarian tumor progression through recruitment of multipotent mesenchymal stromal cells. Proc Natl Acad Sci U S A 106: 3806–3811.
4. Karnoub AE, Dash AB, Vo AP, Sullivan A, Brooks MW, et al. (2007) Mesenchymal stem cells within tumour stroma promote breast cancer metastasis. Nature 449: 557–563.
Because MSCs are multipotental (that is they differentiate into several different adult tissues), they can serve the tumor as a source of blood vessels that augment tumor metastasis and growth. However, several pre-clinical studies with genetically engineered MSCs that deliver chemotherapuetic agents to tumors have proven quite successful (see Waterman RS, Betancourt AM (2012) The role of mesenchymal stem cells in the tumor microenvironment: InTech). So what are we to believe? After MSCs good or bad as tumor treatments?
In 2010, Aline M. Betancourt and colleagues at Tulane University, New Orleans, Louisiana defined two distinct MSC subypes in a MSC population. They referred to these subtypes as MSC1 and MSC2. When challenged with molecules normally found in invading microorganisms, MSC1 populations tend to promote the immune response, where as MSC2 populations tend to suppress the immune response. This simple priming experiment provided a way to distinguish between the two MSC subtypes, but it also gave stem cell scientists a reason why experiments with MSCs tend to give conflicting results in different laboratories – because the two labs were probably working with populations that consisted of different MSC subtypes. See Waterman RS, Tomchuck SL, Henkle SL, Betancourt AM (2010) A New Mesenchymal Stem Cell (MSC) Paradigm: Polarization into a Pro-Inflammatory MSC1 or an Immunosuppressive MSC2 Phenotype. PLoS ONE 5(4): e10088. doi:10.1371/journal.pone.0010088.
With this in mind, Betancourt and co-workers examined the ability of the distinct MSC subtypes to interact with cancers. When grown in culture with several different types of tumor-causing cell lines, they discovered that MSC1 do not support tumor growth but MSC2 robustly support tumors growth. MSC2 also increased the ability of the tumors to invade other tissues and migrate in culture whereas MSC1 supported neither tumor invasion nor tumor migration.
Other features were different as well. For example, MSC1 recruited a completely different cadre of white blood cells to the tumor when compared to MSC2. Also, the molecules deposited in the vicinity of the tumor by MSC1 and MSC2 differed greatly. By providing a bed of molecules upon which tumors cell like to move and grow, MSC2s promoted tumor cell activity, but the materials laid down by MSC1 were not nearly as attractive to the tumor cells.
These show why MSCs can promote the growth of particular tumors in some experiments but not others. Furthermore, it shows that there is a relatively simple test to separate these two MSC subtypes. All further pre-clinical experiments with MSCs, should account for these distinct MSC subtypes and determine if one MSC subtype is a better candidate for an anticancer treatment regime than the other.
See Waterman RS, Henkle SL, Betancourt AM (2012) Mesenchymal Stem Cell 1 (MSC1)-Based Therapy Attenuates Tumor Growth Whereas MSC2-Treatment Promotes Tumor Growth and Metastasis. PLoS ONE 7(9): e45590. doi:10.1371/journal.pone.0045590.
A very nice entry from the Stem Cell Blog. Danish stem cell scientists have had unparalleled success generating insulin-producing cells from stem cells if they grow them in a three-dimensional culture. Check it out. You will be glad you did.
Scientists have reported improved results for creating insulin-producing cells within a 3 dimensional environment, as opposed to the standard 2 dimension within a Petri dish. By creating an environment that mimics the inside of an embryo, scientists are able to use this new knowledge to improve diabetes treatment and stem cell treatments for chronic diseases of internal organs.
Scientists from The Danish Stem Cell Center (DanStem) at the University of Copenhagen are contributing important knowledge about how stem cells develop best into insulin-producing cells. In the long-term this new knowledge can improve diabetes treatment with cell therapy. The results have just been published in the scientific journal Cell Reports.
Stem cells are responsible for tissue growth and tissue repair after injury. Therefore, the discovery that these vital cells grow better in a three-dimensional environment is important for the future treatment of disease with stem cell therapy. “We can see that…
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Bone injuries and bone diseases sometimes require bone grafts for proper treatment. In order to find bone for implantation, orthopedic surgeons often take bone from other locations in the body, use bone from cadavers or synthetic compounds that promote the formation of new bone. Bone grafting is a complex surgical procedure and even though it can replace missing bone, it poses a significant health risk to the patient, and sometimes completely fails to foster proper healing.
Bone has the ability to regenerate, but it requires very small fracture space or some sort of scaffold in order to make new bone. Bone grafts can provide that scaffold. A bone graft can be “autologous,” which simply means that the bone is harvested from the patient’s own body (often from the iliac crest), or the graft can be an allograft, which consists of cadaveric bone usually obtained from a bone bank. Finally, synthetic bone grafts are made from hydroxyapatite or some other naturally occurring, biocompatible substance such as Bioglass, tricalcium phosphate, or calcium sulfate.
Making natural bone from stem cells is one of the goals of regenerative medicine, and work from Irving I. Weissman at Stanford University has shown that this hope is certainly feasible.
Weissman and his colleagues evaluated the ability of embryonic stem cells and induced pluripotent stem cells to form bone in a culture environment known to induce bone formation in most circumstances. This culture system (known as an osteogenic microniche) consisted of a scaffold made of poly – L-lactate coated with hydroxyapatite and stuffed with a growth factor called bone morphogen protein-2 (BMP-2). BMP-2 is a known inducer of bone formation and this scaffold is placed inside the bone of a laboratory animal that has suffered a fracture.
After implanting pluripotent stem cells into these osteogenic microniches, they were very pleasantly surprised to find that both embryonic stem cells and induced pluripotent stem cells embedded themselves into the scaffold and differentiated into bone making cells (osteoblasts). They also made new bone and did so without forming any tumors.
These results suggest that local signals from the implanted scaffold and the genera environment within the bone directed the cells to survive and differentiate into osteoblasts. Thus pluripotent stem cells may have the clinical capacity to regenerate bone, which would, potentially preclude the need for risky bone grafting procedures.
Mesenchymal stem cells (MSCs) are found in multiple tissues and locations throughout our bodies, and they have the ability to differentiate into bone, fat, cartilage, and smooth muscle. MSCs also have the ability to suppress unwanted immune responses and inflammation. Therefore, MSCs are prime candidates for regenerative medical treatments.
MSCs have been used to experimentally treat traumatic brain injury (for example, Galindo LT et al., Neurol Res Int 2011;2011:564089). One of the main concerns after traumatic brain injury is damage to the blood brain barrier (BBB). BBB damage allows inflammatory cells to access the brain and further damage it. Therefore, healing the damage to the BBB or protecting the BBB after a traumatic brain injury is vital to the brain after a traumatic brain injury.
After a traumatic brain injury, the vascular system suffers damage and begins to leak. When blood leaks into tissues, it tends to irritate the tissues and damage them. MSCs release a soluble factor known as TIMP3 (tissue metalloproteinase-3) that degrades blood-based proteins known to cause damage to tissues when blood vessels leak. TIMP3 production by MSCs can also protect the BBB from degradation after a traumatic brain injury.
Researchers from the University of Texas Health Sciences Center, UC San Francisco, and two biotechnology companies have examined the protective role of MSCs and one particular protein secreted by MSCs in protecting the BBB after traumatic brain injury.
Shibani Pati, from UC San Francisco, and his collaborators from the University of Texas, Houston, MD Anderson Cancer Center, Amgen, and Blood Systems Research Institute (San Francisco) used MSCs to staunch the increased permeability the BBB after a traumatic brain injury.
They used a mouse model in these experiments and induced traumatic brain injuries in these mice. Then they gave MSCs to some, and soluble TIMP3 to others, and buffer to another group as a control. They discovered that the MSCs mitigated BBB damage after a traumatic brain injury. However, they also found that soluble TIMP3 could also protect the BBB approximately as well as MSCs. This suggested that the TIMP3 secretion by MSCs is the main mechanism by which MSCs protect the BBB after a traumatic brain injury.
To test this hypothesis, Pati and his colleagues administered MSCs to mice that had experienced traumatic brain injury, but they also co-administered a soluble inhibitor to TIMP3. They discovered that this inhibitor completely abolished the ability of MSCs to protect the BBB after a traumatic brain injury. They also found that the main target of TIMP3 was vascular endothelial growth factor. Apparently after a traumatic brain injury, massive release of vascular endothelial growth factor causes the breakdown of BBB structures. TIMP3 degrades vascular endothelial growth factor, which prevents BBB breakdown.
These findings suggest that administration of recombinant proteins such as TIMP3 after a traumatic brain injury can protect the BBB and decrease brain damage. Clinical trial anyone?
Spinal cord injuries are a very difficult challenge for regenerative medicine. The damaged spinal cord is a toxic waste dump encased in a barrier that prevents regenerating cells from entering or exiting. However, a group of stem cells that have been used in clinical trials have produced extremely encouraging results for spinal cord injury patients.
Collaboration between the Cambridge University’s Veterinary School and Medical Research Council’s Regenerative Medicine Centre, has given scientists a chance to test a particular type of stem cell found inside your nose to regenerate the damaged part of the spinal cord of dogs. The researchers are cautiously optimistic that their work could play an important role in the future treatment of human patients who suffer from similar injuries, but only if they are used in combination with other treatments.
For over a decade, scientists have known about olfactory ensheathing cells (OECs) and their potential usefulness for treating damaged spinal cords. OECs have unique properties, since they have the ability to support nerve fiber growth. This is the role OECs play in the nose; they maintain a pathway for the growth and extension of nerve fibers between the nose and the brain.
Previous research in laboratory animals has shown that OECs can aid regeneration of those extensions of nerve cells that transmit signals (axons). The growth and re-extension of damaged neurons helps them form a kind of bridge between damaged and undamaged spinal cord tissue. A Phase 1 trial in human patients with spinal cord injuries (SCI) established that transplantation of OECs into the spinal cords of SCI patients is safe.
This present study was published in the latest issue of the neurology journal Brain, and it is the first double-blinded randomized controlled trial to test the effectiveness of OEC transplants to improve function in ‘real-life’ spinal cord injury. The trial was performed on animals that had spontaneous and accidental injury rather than in the controlled environment of a laboratory. Unlike other experiments, these test subjects had suffered their spinal cord injuries at least one year ago. Thus, this experiment more closely resembles the way in which this procedure might be used in human patients.
The 34 pet dogs had all suffered severe spinal cord injuries. Twelve months or more after the injury, they were unable to use their back legs to walk and unable to feel pain in their hindquarters. Not surprisingly, many of the dogs were dachshunds, which are particularly prone to this type of injury because of their long body and short legs. Additionally, dogs are more likely to suffer from SCIs because the spinal cord may be damaged as a result of what in humans is the relatively minor condition of a slipped disc. Thus while four-leggedness has its advantages, it also has its drawbacks.
In this study, which was funded by the MRC, one group of dogs had OECs from the lining of their own nose injected into the injury site. The other group of dogs was injected only with the liquid in which the cells were transplanted. Neither the researchers nor the owners (nor the dogs!) knew which injection they were receiving.
The dogs were observed for adverse reactions for 24 hours before being returned to their owners. After this time, the animals were tested at one month intervals for neurological function and to have their gait analyzed on a treadmill while being supported in a harness. In particular, researchers were interested in the ability of the dogs to coordinate the movement of their front and back limbs.
The group of dogs that had received the OEC injection showed considerable improvement that was not seen in the other group. Just view this video here to see the amazing improvement in the OEC transplanted animals. These animals moved previously paralyzed hind limbs and coordinated all their movement with their front legs (again, see this video). This means that in these dogs neuronal messages were being conducted across the previously damaged part of the spinal cord. However, the researchers established that the new nerve connections accounting for this recovery were occurring over short distances within the spinal cord and not over the longer distances required to connect the brain with the spinal cord.
Professor Robin Franklin, a co-author of the study from the Wellcome Trust-MRC Cambridge Stem Cell Institute, University of Cambridge, said: “Our findings are extremely exciting because they show for the first time that transplanting these types of cell into a severely damaged spinal cord can bring about significant improvement. We’re confident that the technique might be able to restore at least a small amount of movement in human patients with spinal cord injuries but that’s a long way from saying they might be able to regain all lost function. It’s more likely that this procedure might one day be used as part of a combination of treatments, alongside drug and physical therapies, for example.”
The head of Regenerative Medicine at the Medical Research Council, Dr. Rob Buckle, commented: “This proof of concept study on pet dogs with the type of injury sustained by human spinal patients is tremendously important and an excellent basis for further research in an area where options for treatment are extremely limited. It’s a great example of collaboration between veterinary and regenerative medicine researchers that has had an excellent outcome for the pet participants and potentially for human patients.”
The researchers stress that human patients with a spinal injury rate a return in sexual function and continence far higher than improved mobility. Some of the dogs in the study did regain bowel and bladder control but the number of these was not statistically significant.
Mrs. May Hay, the owner of a dog named Jasper, who took part in the trial (and can be seen in the video), said: “Before the trial, Jasper was unable to walk at all. When we took him out we used a sling for his back legs so that he could exercise the front ones. It was heartbreaking. But now we can’t stop him whizzing round the house and he can even keep up with the two other dogs we own. It’s utterly magic.”
Human patients have already been treated with their own OECs. Jacki Rabon traveled to Brazil to receive an OEC transplantation with her own OECs. Today, even though she has been severely spinal cord injured, she can walk with braces. Read her story here. Another patient, Laura Dominguez, was also treated by the same Brazilian physician. See her video here. It certainly seems as though we have hit upon a sound strategy upon which to build. Let’s pursue this rather than killing human embryos.
Recently, I blogged on blood vessel-making stem cells located in the walls of blood vessels. New work on these cells from the University of Pittsburgh has shown that these CD146+ cells can also abate heart damage after a heart attack.
The ability of endothelial progenitor cells or EPCs to repair skeletal muscle is well established, but the ability of these cells to repair a damaged heart is unknown. Johnny Huard from the McGowan Institute for Regenerative Medicine at the University of Pittsburgh and his group investigated the therapeutic capabilities of human blood vessel-derived EPCs that had been isolated from skeletal muscle to treat heart disease in mice.
When mice that had been given infusions of EPCs after a heart attack were compared with mice that had received a placebo, the EPC transplanted mice definitely fared much better. Echocardiographic studies of the hearts showed that EPC transplantation reduced enlargement of the left ventricle (the main pumping chamber of the heart), and also significantly improved the ability of the heart to contract.
In addition to comparing the ability of EPCs to improve the function of the heart after a heart attack with placebos, they were also compared to stem cells known to make skeletal muscle. These stem cells are called “CD56+ myogenic progenitor cells,” which is a mouthful. CD56+ myogenic progenitor cells or CD56+ MPCs can form skeletal muscle; and infusions of them can improve the structure of the heart after a heart attack and prevent it from deteriorating. However, transplanted EPCs were superior to CD56+ MPCs in their ability to heal the heart after a heart attack.
The transplanted EPCs were able to substantially reduced scarring in the heart, and significantly reduced inflammation in the heart. In fact, then the culture medium in which EPCs were grown was injected into mouse hearts after a heart attack, this medium also suppressed inflammation in the heart.
When Huard and his co-workers examined the genes made in the EPCs, they found that these stem cells cranked out proteins known to decrease inflammation (IL-6, LIF, COX-2 and HMOX-1 for those who are interested), especially when the cells were grown under low oxygen conditions. This is significant because in the heart after a heart attack, blood vessels have died off and the supply of blood to the heart is compromised. The fact that these cells are able to do this under these harsh conditions shows that they make exactly the most desirable molecules under these conditions.
The biggest boon for these cells came from examinations of blood vessel formation in the heart. Blood vessel production in the EPC-transplanted hearts was significantly increased. The EPCs formed a host of new blood vessels and extending “microvascular structures” or smaller supporting blood vessels and larger capillary networks too.
Once again, when grown under oxygen poor conditions, the EPCs jacked up their expression of pro-blood vessel-making molecules (VEGF-A, PDGF-β, TGF-β1 and their receptors). When EPCs were labeled with a green-glowing protein, fluorescence tracking showed that they actually fused with heart cells, although it must be emphasized that this was a minor event.
These pre-clinical studies show remarkable improvements in the heart after a heart attack, and they apparently induce these improvements through several different mechanisms. They make new structures and they secrete useful molecules. These significantly successful results should provide the basis for clinical trials with these cells.
When I was a kid, I used to wish that I had no sweat glands. Sweating made me sticky, wet and miserable. Little did I now, that without sweat glands, my body would have quickly overheated to fatal levels. A new study now shows that sweat glands are also the source of healing for wounds.
Human skin contains millions of eccrine sweat glands. These glands are not connected to hair follicles and they function throughout our lives to regulate the temperature of the body. Sweat glands respond to elevated bodily temperatures by secreting a mixture of NaCl and water. The water cools the external bodily temperature and is used to secrete other unwanted molecules. This is the main reason our sweat can smell like the food we ate (garlic, onions, etc.).
A new study by from the University of Michigan Health System shows that sweat glands play a key role in providing cells for recovering skin wounds, such as scrapes, burns and ulcers. These results were recently published in the American Journal of Pathology.
“Skin ulcers – including those caused by diabetes or bed sores – and other non-healing wounds remain a tremendous burden on health services and communities around the world,” says lead author of this work, Laure Rittié, who is a research assistant professor of dermatology at the Univ. of Michigan Medical School. She continued, “Treating chronic wounds costs tens of billions of dollars annually in the U.S. alone, and this price tag just keeps rising. Something isn’t working.”
U of M researchers believe they have discovered one of the body’s most powerful secret healers.
“By identifying a key process of wound closure, we can examine drug therapies with a new target in mind: sweat glands, which are very under-studied,” Rittié says. “We’re hoping this will stimulate research in a promising, new direction.”
Previously, wound healing was thought to originate from cells that came from hair follicles and from intact skin at the edge of the wound. However, the findings from the U of M research group demonstrate that cells arise from beneath the wound, and suggest that human eccrine sweat glands are the source of an important reservoir of adult stem cells that can quickly be recruited to aid wound healing.
Rittié commented: “It may be surprising that it’s taken until now to discover the sweat glands’ vital role in wound repair. But there’s a good reason why these specific glands are under-studied – eccrine sweat glands are unique to humans and absent in the body skin of laboratory animals that are commonly used for wound healing research.” Rittié continued: “We have discovered that humans heal their skin in a very unique way, different from other mammals. The regenerative potential of sweat glands has been one of our body’s best-kept secrets. Our findings certainly advance our understanding of the normal healing process and will hopefully pave the way for designing better, targeted therapies.”
A research team led by Virginia Lee, who works as a neurobiologist at the University of Pennsylvania in Philadelphia has provided a mechanism for how misfolded proteins cause Parkinson’s disease. Lee’s group has resurrected an old treatment strategy that was discarded long ago that just might to slow the progression of this neurological disease.
Alpha-synuclein is a strange name for a protein, but it is a specifically found in the nervous system. Alpha-synuclein protein can compose as much as 1% of all the protein in the cytoplasm of a neuron. It is found all over the brain. What this protein actually does is a bit of a mystery, but the latest data suggests that alpha-synuclein helps traffic proteins from membranes to other places in the cell (Cooper et al., (2006). Science 313: 324–328).
In the brains of patients with Parkinson’s disease, neurons accumulate protein aggregates known as Lewy bodies. A major component of Lewy bodies is alpha-synuclein that has folded in an aberrant manner. These aggregations of misfolded alpha-synuclein cause a variety of problems inside cells that culminate in the death of the neuron.
This is the story of Parkinson’s disease so far, but Lee and her colleagues injected a misfolded synthetic version of α-synuclein into the brains of normal mice and saw the key characteristics of Parkinson’s disease develop and progressively worsen. While that is not a surprise, what Lee and co-workers found when they examined the brains of the injected laboratory animals astounded them. This study, which was published in the journal Science, shows that the injected misfolded alpha-synuclein was able to spread from one nerve cell to another. Therefore, the malformed protein did not just take up residence inside neurons, but instead was able to travel from one neuron to another.
Apparently, cells affected by misfolded alpha-synuclein are able to secrete it into the areas that surround them and this secreted protein is taken up by healthy cells. Once taken up, the misfolded alpha-synuclein induces the normal copies of the alpha-synuclein protein snap into the misfolded conformation. This eventually kills off the once-healthy neuron and also turns it into a new factory for the secretion of misfolded alpha-synuclein, which them goes on to damage other neurons.
This finding, however, raises the possibility that an antibody that binds the misfolded α-synuclein could potentially bind the protein and prevent it from passing between nerve cells. “It’s very hard to ask antibodies not only to get inside the brain, but to get inside cells,” says Lee. “But now you have the possibility of stopping the spreading. And if you stop the spreading, perhaps you can slow the progression of the disease.”
The tendency of the pathology of Parkinson’s disease to spread from neuron to neuron by a rogue protein was actually suggested in 2008. Fetal neural tissue transplants were used to treat Parkinson’s patients, but upon post-mortem examination of the transplanted fetal tissue, it was quickly recognized that these transplants has developed the characteristic Lewy bodies associated with Parkinson’s disease. This indicated that the nearby diseased cells were able to infect the transplanted tissue with Parkinson’s disease. Subsequent studies have shown that misfolded alpha-synuclein does spread between neighboring cells and induce cell death (Desplats, P. et al. Proc. Natl Acad. Sci. USA 106, 13010–13015 (2009).). The neurons, apparently, can release vesicles filled with misfolded alpha-synuclein in the same way they release neurotransmitters. This release bathes the nearby cells in misfolded alpha-synuclein, but there are still questions as to whether or not the misfolded alpha-synuclein is responsible for the cascade of brain damage seen in Parkinson’s.
Lee says that her team has now captured the full consequences of runaway α-synuclein in the brain. “We knew this transfer from one cell to another can happen, but whether it could play a significant role in the disease was still open,” says Tim Greenamyre, director of the Pittsburgh Institute for Neurodegenerative Diseases in Pennsylvania, who was not involved in the latest work.
Besides Lewy bodies, the brains of patients with Parkinson’s disease also show a dramatic loss of those neurons that produce the chemical messenger dopamine. When Lee’s team injected the misfolded α-synuclein into a part of the mouse brain rich in dopamine-producing cells, Lewy bodies began to form, followed by the death of dopamine neurons. Nerve cells linked to those near the injection site also developed Lewy bodies, which showed that cell-to-cell transmission was occurring.
Greenamyre says that is possible, but hasn’t yet been proved. “All of the cells affected in this paper were those directly in contact with the injection site,” he says. But, within six months of the injection, coordination of movement, grip strength and balance had all deteriorated in the mice, which is a recapitulation of what occurs in people with Parkinson’s disease.
“It’s really pretty extraordinary,” says Eliezer Masliah, a neuroscientist at the University of California, San Diego. “We have been trying that experiment for a long time in the lab and we have not seen such dramatic effects.” According to Masliah, Lee’s work provides the impetus for that handful of biotechnology companies that are sponsoring clinical trials of alpha-synuclein antibodies for as therapeutic agents for Parkinson’s disease. Masliah hopes that this will also motivate neuroscientists to examine exactly how the protein enters and exits cells.
There is still one mystery that has not been addressed to data: why do the Lewy bodies appear in the first place? “Parkinson’s disease is not a disorder in which somebody injects synuclein into your brain,” notes Ted Dawson, director of the Institute for Cell Engineering at Johns Hopkins University in Baltimore, Maryland. “So what sets it in motion?” Clearly some mutations in the gene that encodes alpha-synuclein increase the tendency for this protein to spontaneously misfold. But this also suggests that there are particular triggers that lead to such events. The nature of these triggers will certainly be the subject of future work.
This case has been brewing on the web for a while. A 31-year old dentist who was 17-weeks pregnant named Savita Halappanavar went to the hospital in Galway, Ireland with severe back pain. After an examination, she was found to be in the process of a miscarriage, but the doctors kept a wait and see approach. There were concerned that there was a fetal heart beat and that Irish law does not permit the termination of a pregnancy when the baby is still alive. The poor woman died three days later from septicemia. The whole thing seems rather dodgy at first glance.
The facts have yet to completely come out. Therefore, rushing to judgment seems rash. Having said that, Dr. Jen Gunter, a Canadian OBGYN has blogged on the clinical aspects of the case and is quite convinced that the Irish physicians did not follow established medical protocol.
See Dr. Gunter’s analysis here. She believes that Irish law allows for termination of pregnancies when there is a clear medical need for such termination, and according to Dr. Gunter, there was a clear need in this case. Her reasons are quite compelling. Read and see for yourself.
University of Washington researchers have done something seemingly impossible: they have removed the extra copy of chromosome 21 in cells taken from a patient with Down syndrome. This gene therapy technique targets only the extra genetic material in the cell, and scientists were able to successfully remove the extra chromosome 21 without damaging the integrity of the rest of the chromosomes present in the nucleus.
The first reaction to this news is to shout, “there’s a cure for Down Syndrome!” Unfortunately that is not the case. However, it might be a way to treat Down Syndrome patients who have blood cancers. Down syndrome patients are at increased risk for leukemia, and this technique, pioneered by Dr. David Russell and his colleagues is meant to fix the errant bone marrow cells in culture and then reintroduce the fixed cells back into the patient.
Dr. Russell explained: “We are certainly not proposing that the method we describe would lead to a treatment for Down syndrome. What we are looking at is the possibility that medical scientists could create cell therapies for some of the blood-forming disorders that accompany Down syndrome.” Dr. Russell is from the University of Washington’s Department of Medicine.
This technique works on cultured cells grown in a laboratory. The cells are infected with an engineered virus that inserts into the extra chromosome. Then the cells are grown under conditions that kill all cells with the viral DNA. Only those cells that spontaneously lose the extra copy of chromosome 21 survive the culture conditions.
This protocol could potentially treat Down syndrome patients with leukemia with genetically-modified stem cells that are derived from their own cells, but lack the extra chromosome. Stem cells could be taken from the bone marrow of the patients, the doctors could remove the extra chromosome, and then the healthy cells could then be grown and transplanted back into the bone marrow of the patient. This same technique could also be used for leukemia patients whose bone marrow cells have an extra chromosome, but do not have Down syndrome.
This is great news for those with Down syndrome and for all those who live with any kind of trisomy. Also, since gene therapy can introduce new defects into the patient’s DNA, this technique could potentially remove unwanted extra bits of DNA without adversely affecting other chromosomes. This is certainly a major achievement.
A large and very well designed and carefully controlled clinical trial known as TIME has failed to demonstrate any benefit for infusions of bone marrow stem cells into the heart 3-7 days after a heart attack. This study comes on the heals of a similar clinical study known as LateTIME, which stands for Late Timing In Myocardial infarction Evaluation, and tested the effects of bone marrow stem cells infusions into the heart of heat attack patients 2-3 weeks after a heart attack.
LateTIME enrolled 87 heart attack patients, and harvested their bone marrow stem cells. The stem cells were delivered into the hearts through the coronary arteries, but some received a placebo. All patients had their ejection fractions measured, their heart wall motions in the damaged areas of the heart and outside the damaged areas and the size of their infarcts. There were no significant changes in any of these characteristics after six months. Because another large clinical study known as the REPAIR-AMI study showed significant differences between heart attack patients that had received the placebo and those that had received bone marrow stem cells 3-7 days after a heart attack, this research group, known as the Cardiovascular Cell Therapy Research Network (CCTRN), sponsored by the National Institutes of Health, decided the test their bone marrow infusions at this same time frame.
TIME was similar in design to LateTIME. This study enrolled 120 patients that had suffered a heart attack and all patients received either an infusion of 150 million bone marrow stem cells or a placebo within 12 hours of bone marrow aspiration and cell processing either 3 days after the heart attack to 7 days. The researchers examined the changes in ejection fraction, movement of the heart wall, and the number of major adverse cardiovascular events plus the changes in the infarct size.
The results were resoundingly negative. At 6 months after stem cell infusion, there was no significant increase in ejection fractions versus the placebo and no significant treatment effect on the function of the left ventricle in either the infarct or the border zones. These findings were the same for those patients that received bone marrow stem cell infusions 3 days after their heart attack or 7 days after their heart attacks. Fortunately, the incidence of major adverse events were rare among all treatment groups.
Despite the negative results for these clinical trials, there are a few silver linings. First of all, the highly controlled nature of this trial sets a standard for all clinical trials to come. A constant number of stem cells were delivered in every patient, and because the stem cells were delivered soon after they were harvested, there were no potential issues about bone marrow storage.
Jay Traverse, the lead author of this study, made this point about this trial: “With this baseline now set, we can start to adjust some of the components of the protocol to grow and administer stem cell [sic] to find cases where the procedure may improve function. For example, this therapy may work better in different population groups, or we might need to use new cell types or new methods of delivery.”
When one examines the data for this study, it is clear that some patients definitely improved dramatically, whereas others did not. Below is a figure from the Traverse et al paper that shows individual patient’s heart function data 6 months after the stem cell infusions.
From examining these data even cursorily, it is clear that some patients improved dramatically while others tanked. Traverse is convinced that bone marrow stem cell infusions help some people, but not others (just like any other treatment). He is convinced that by mining these data, he can begin to understand who these patients are who are helped by bone marrow stem cell transplants and who are not. Also, the stem cells of these patients have been stored. Hopefully, further work with them will help Traverse and his colleagues clarify what, if anything, about the bone marrow of these patients makes them more likely to help their patients and so on.
There are some possible explanations for these negative results. Whereas the positive REPAIR-AMI used the rather labor-intensive Ficoll gradient protocols for isolating mononculear cells from bone marrow aspirates, the TIME trials used and automated system for collecting the bone marrow mononuclear cells. Cells isolated by the automated system have neither been tested in an animal model of heart attacks, nor established as efficacious in a human study of heart disease. Therefore, it is possible that the bone marrow used in this study was largely dead. Secondly, the cell products were kept in a solution that had a heparin concentration that is known to inhibit the migratory properties of mononuclear cells (See Seeger et al., Circ Res 2012 111(7): 1385-94). Therefore, there is a possibility that the bone marrow used in this study was no good. Until the bone marrow stem cells collected by this method are confirmed to be efficacious, judgment must be suspended.
This has been all over the web, but Wesley Smith at his Human Exceptionalism blog on the National Review Online web site has probably the best take on it.
A Canadian man named Scott Routley suffered severe brain damage in a car accident 12 years ago, and since then, he has not provided physicians with any evidence that he is conscious. Several physical assessments by health care professionals have not indicated that Mr. Routley shows any signs of awareness, or has the ability to communicate.
What types of assessments are given to these patients? The Royal Hospital for Neuro-disability (RHN) in Putney, London, specializes in the rehabilitation of brain-injured patients. The RHN invented a complex assessment technique for brain-damaged patients that has been given the clever acronym “SMART.” SMART tests all five senses, and a SMART assessment asks patients to track objects with their eyes, press switches, look at photographs, and even gives them things to taste and smell.
Patients who uniformly fail to show any signs of sensation in a SMART assessment (and others) are thought to be in a “persistent vegetative state.” Essentially the brain stem still works to get the heart pumping and the lungs breathing, but these are autonomic functions provided by vital centers in the brain stem. There cerebral cortex and the so-called “higher brain functions” that many people equate with being a human person, are thought to be gone.
Sometimes, patients in a persistent vegetative state will awaken to a kind of coma, in which their eyes are open, but they do not seem to have any perception of themselves or the outside world.
This view of severely brain-damaged patient will need to be rewritten, according to British neuroscientist Prof Adrian Owen. Owen directed a neurological research team at the Brain and Mind Institute at the University of Western Ontario that examined Mr Routley’s brain with fMRI (fiunctional magnetic resonance imaging). Their data, in Owen’s view shows that Mr. Routley is clearly not vegetative.
According the Dr. Owen, “”Scott has been able to show he has a conscious, thinking mind. We have scanned him several times and his pattern of brain activity shows he is clearly choosing to answer our questions. We believe he knows who and where he is.”
Dr. Owen continued: “Asking a patient something important to them has been our aim for many years. In future we could ask what we could do to improve their quality of life. It could be simple things like the entertainment we provide or the times of day they are washed and fed.”
Folks, being able to answer questions is not something that patients in persistent vegetative states do. This chap and probably hundreds or more like him are alive and their brains are functioning. Their brains however are too damaged to make their bodies move beyond so-called “core reflexes.”
Wesley Smith brings up the poignant point to be taken from all this: “People such as Routley are dehydrated to death every day in all fifty states and in many countries around the world by having their tube-supplied sustenance withdrawn–supposedly based on their lack of personhood. But don’t expect this to stop the dehydration imperative. Bioethicists will merely say this is even more reason to kill them since they are aware of their profound disabilities and suffering. Indeed, that argument has already started.”
Smith is dead-on. There are plenty of cases of supposedly brain-dead patients suddenly regaining abilities after being out of it for a long time. For example, Haleigh Poutre, who was beaten into a coma by her stepfather Jason Strickland and her maternal aunt Holli Strickland. The Department of Social Services, which had failed to rescue her from an obviously abusive situation in the first place, took custody of her and ordered her to be killed by dehydration and starvation. However, this order was stayed after Haleigh began to breathe on her own and follow simple commands. There are many other cases like this and do not get me started on Terry Schiavo (no I am not going to let that one go).
We are putting people down as though they were our pets just because they do sit up a bark when we say so. Our original moral instincts were correct in the first place – that people are people regardless of whether or not they can follow our instructions. May God forgive us for what we have done to the most disabled among us. Hopefully, brain scans such as these will become mandatory before a patient is starved to death in the name of “mercy killing,” which is just simple murder.
The laboratory of Petri Salven at the University of Helsinki, Helsinki, Finland, has discovered a new type of stem cell that play a decisive role in the growth of new blood vessels. These stem cells are found in the walls of blood vessels and if protocols are developed to isolated these stem cells, they might very well provide news ways to treat cardiovascular diseases, cancer and many other diseases.
The growth of new blood vessels is known angiogenesis. Angiogenesis is required for the repair of damaged tissues or organs. A downside of angiogenesis is that tumors often secrete angiogenic factors that induce the circulatory system to remodel itself so that new blood vessels grow into the tumor and feed it so that it can grow faster. Thus angiogenesis research tries to promote the growth of new blood vessels when they are needed and inhibit angiogenesis when it is unwanted.
Several drugs that inhibit angiogenesis have been introduced as adjuvant cancer treatments. For example, the drug bevacizumab (Avastin) is a monoclonal antibody that specifically recognizes and binds to an angiogenic factor known as vascular endothelial growth factor or VEGF. When VEGF receptors on the surface of normal endothelial cells. When VEGF binds to receptors on the surfaces of endothelial cells, a signal is sent within those cells that initiate the growth and survival of new blood vessels. Bevacizumab binds tightly to VEGF, which prevents it from binding and activating the VEGF receptor.
Other angiogenesis inhibitors include sorafenib (Nexavar) and sunitinib (Sutent), which are small molecular inhibitors of the receptors that bind the angiogenic factors and the downstream targets of those receptors. Unfortunately, the present crop of angiogenesis inhibitors are not all that effective under certain conditions and they are also extremely expensive and have some very undesirable side effects.
Professor Salven has studied angiogenesis for some time, and his research has focused on the endothelial cells that compose blood vessels. Where do these cells come from and how can we make more or less of them as needed?
A long-standing assumption by scientists in the angiogenesis field was that new endothelial cells came from stem cells found in the bond marrow. This assumption makes sense since there are several stem cell populations in bone marrow that express blood vessel markers and can form blood vessels in culture. However, in 2008, Salven’s group published a paper that demonstrated that new endothelial cells could not come from bone marrow stem cells (see Purhonen S, et al., (2008). Proc Natl Acad Sci U S A. 105(18): 6620-5). Therefore, the mystery remained – from where do new endothelial cells come?
Salven has recently solved this conundrum in his recent paper that appeared in PLoS Biology. According to Salven, “We succeeded in isolating endothelial cells with a high rate of division in the blood vessels of mice. We found that these same cells in human blood vessels and blood vessels growing in malignant tumors in humans. These cells are known as vascular endothelial stem cells, abbreviated VESC. In a cell culture, one such cell is able to produce tends of millions of new blood vessels wall cells.”
Slaven continued: “Our study found that these important stem cells can be found as single cells among the ordinary endothelial cells in blood vessel walls. When the process of angiogenesis is launched, these cells begin to produce new blood vessel wall cells.”
Salven’s colleagues have tested the effects of these new endothelial cells in mice. A particular mouse strain that carries a mutation in the c-kit gene was examined in these experiments. The c-kit gene encodes a cell surface protein called CD117, which is a vital element in the cells that form blood vessels. IN these c-kit mutant mice, new growth of new blood vessels was very poor and the growth of malignant tumors was also quite poor. However, if new stem cells from animals that did not possess a mutation in the c-kit gene were implanted into these mutant mice, blood vessels quickly formed.
As previously mentioned, the cell surface protein CD117 does seem to mark VESCs, but other cells other than VESCs have CD117 on their surfaces. Therefore, isolating all CD177-expression cells only enriches preparations for VESCs; it does not isolate VESCs. Presently, Salven and his group are searching for better surface molecules that can be used to more effectively isolated VESCs from surrounding tissue. If this isolation succeeds, then it will be possible to isolated and propagate VESCs from patients with cardiovascular diseases and expand them in culture for therapeutic purposes.
Another potentially fertile field of research is to find a way to inhibit the activity of VESCs to prevent tumors from remodeling the circulatory system. By cutting of their blood supply, tumors will not only grow slower, but also not spread nearly as quickly.
See: Fang S, Wei J, Pentinmikko N, Leinonen H, Salven P (2012) Generation of Functional Blood Vessels from a Single c-kit+ Adult Vascular Endothelial Stem Cell. PLoS Biol 10(10): e1001407. doi:10.1371/journal.pbio.1001407
John Dick is a senior scientist at the University Health Network’s McEwen Centre for Regenerative Medicine and a professor at the University of Toronto. He is also the senior investigator for a study that includes a collaboration between Canadian and Italian stem cell scientists that examined ways to expand human blood stem cells for human use.
A new master control gene was identified in this study that, when manipulated, could increase stem cell production.
In the words of Dick, “For the first time in human blood stem cells, we have established that a new class of non-coding RNA called miRNA represents a new tactic for manipulating these cells, which opens the door to expanding them for therapeutic uses.”
In 2011, Dick’s research group published a landmark paper in which he and his colleagues succeeded in isolating “CD49f+” cells. Just one of these CD49f+ cells could reconstitute an entire blood-cell making system in bone marrow. It has been known for some time that the population of blood cell-making stem cells in bone marrow is rather heterogeneous, and some cells have tremendous regenerative capacities, but others shown only slight regenerative abilities. DIck’s group isolated bone marrow stem cells that could replenish the whole blood-making system of a laboratory animal (see Notta, et al., Science 333, 218-221).
Dick has also pioneered the field of cancer stem cells when his lab identified leukemia stem cells in 1994 (Lapidot T, et al., Nature. 367, 645-8.) and colon cancer cells in 2007 (O’Brien CA, et al. Nature. 445, 106-10).
The lead author of this study, Eric Lechman, recounted his laboratory work with a master control gene known as microRNA 126 or miR-126. THis small RNA normally silences the expression of many genes, and thus keeps stem cells in a quiescent, dormant state. His strategy in working with miR-126 was to introduce new binding sites into the cell for miR-126 in order to lower the concentration of free miR-126 inside the cell. To do this, he infected stem cells with a genetically engineered virus that was loaded with miR-126 binding sites. The results were remarkable.
According to Lechman, “The virus acted like a sponge and mopped up the specific miRNA in the cells. This enabled the expression of normally expressed genes to become prominent, after which we observed a long-term expansion of the blood stem cells without exhaustion or malignant transformation.”
Given the difficult many labs have has growing sufficient quantities of blood stem cells in the laboratory, this finding could completely revolutionize blood stem cell research and clinical treatments with these stem cells.
According to Dick, “We’ve shown that if you remove the miRNA you can expand the stem cells while keeping their identity intact. That’s the key to long-term stem cell expansion for use in patients.”
Now there’s a word you don’t see everyday: Exosome. What on earth is an exosome? They are small, membrane-enclosed vesicles that are released by cells. Exosomes contain proteins and nucleic acids, and they are have surfaces that are decorated with various types of proteins. Exosomes are 40-100 nm in diameter and there are several different cell types that are known to secrete exosomes. Cancer cells use exosomes to mold surrounding cell into structures that the cancer needs (see Huang et al., (2011). Cancer Lett 315, 28-37 and Cho et al., (2012). Int J Oncol. 40(1):130-138). Likewise, exosomes from mesenchymal stem cells seem to delivery proteins and RNA to heart muscle cells that help them heal after a heart attack (Lai et al., Regen. Med. (2011) 6(4), 481–492). Finally, there have been reports that exosomes can protect against tissue injury such as acute kidney damage (see Bruno S, et al. (2009). J. Am. Soc. Nephrol. 20, 1053–1067.
New work from Harvard University’s Boston Children’s Newborn Medicine division in Massachusetts suggests that exosomes from stem cells can protect the fragile lungs of premature babies from serious lung diseases and chronic lung injury. Mesenchymal stem cells (MSCs) can decrease inflammation under several different conditions. They seem to do so by secreting exosomes that hold inflammatory cells at bay. In a mouse model of lung inflammation, infused MSCs can quell inflammation, but the culture medium in which the MSCs were grown can do as good a job and decreasing inflammation as the whole cells. This suggest that the MSCs are making something that assuages inflammation (see Ionescu, L. et al., (2012). Am J Physiol Lung Cell Mol Physiol. doi: 10.1152/ajplung.00144.2011).
Babies born prematurely have to struggle to get sufficient oxygen into their small, incipient lungs. This causes these poor babies to suffer from chronic oxygen insufficiencies (hypoxia) and they usually need artificial respirators to breathe. The lungs of these babies are susceptible to inflammation and this can lead to chronic lung disease and poor lung function.
Lung inflammation also causes pulmonary hypertension, which simply means that the blood pressure in the artery that carries blood from the heart to the lungs (pulmonary artery) is abnormally high. This causes foaming in the lungs, which reduces gas exchange in the lungs, but the lungs also start to thicken and scar over and that also permanently decreases gas exchange.
Stella Kourembanas is the chair of Boston Medical’s Newborn Medicine Division, and she is heading up investigations into the efficacy of MSC-derived exosomes to stave off inflammation in the lungs of premature babies.
Kourembanas explained, “PH (pulmonary hypertension) is a complex disease fueled by diverse, intertwined cellular and molecular pathways. We have treatments that improve symptoms but no cure, largely because of this complexity. We need to be able to target more than one pathway at a time.”
In 2009, Kourembanas and her colleagues showed that injections of MSCs could prevent PH and chronic lung injury in a newborn mouse model of the disease (Bone marrow stromal cells attenuate lung injury in a murine model of neonatal chronic lung disease (Aslam M, et al., (2009). Am J Respir Crit Care Med. 180(11):1122-30). They also showed that they could achieve the same results by injecting the growth medium that had previously fed the cells.
According to Kourembanas, “We knew, then, that the significant anti-inflammatory and protective effects we saw had to e caused by something released by he MSCs.”
To further their search for factors that heal damaged lungs, Kourembanas and co-workers searched the growth medium of MSCs and they came upon exosomes. By purifying exosomes from the growth medium, Kourembanas’ team showed that the anti-inflammatory effects of the MSCs could be completely recapitulated by simply applying isolated exosomes to the lungs of newborn mice.
Kourembanas said, “We are working to figure out what exactly within the MSC-produced exosomes causes these anti-inflammatory and protective effects. But we know that these exosomes contain microRNAs as well as other nucleic acids. They also induce expression of specific microRNAs in the recipient lung.”
MicroRNAs a small RNA molecules that regulate gene expression. Thousands of microRNAs have been discovered and they are also found in many different biological organisms ranging from plants to worms, to fish, frogs and people.
Kourembanas noted that, “What we may be seeing is the effect of these microRNAs on the expression of multiple genes and the activity of multiple genes and the activity of multiple pathways within the lungs and the immune system all at once.”
Kourembanas hopes that exosome research will someday act alongside stem cell-based therapies. MSC-based exosomes could potentially be used as treatments for premature babies at risk of suffering from chronic lung disease and PH. Also, MSCs are not the only cells that make useful exosomes. Umbilical cord stem cells also secrete exosomes with therapeutic value. Even though many different types of stem cells are recognized by the immune system as foreign, exosomes are not, which gives them an added advantage as therapeutic agents. Kourembanas notes, “they could potentially be collected, banked and given like a drug without the risks of rejection or tumor development that can theoretically come with donor cell or stem cell transplantation.”