Vascular Progenitors Made from Induced Pluripotent Stem Cells Repair Blood Vessels in the Eye Regardless of the Site of Injection


Johns Hopkins University medical researchers have reported the derivation of human induced-pluripotent stem cells (iPSCs) that can repair damaged retinal vascular tissue in mice. These stem cells, which were derived from human umbilical cord-blood cells and reprogrammed into an embryonic-like state, were derived without the conventional use of viruses, which can damage genes and initiate cancers. This safer method of growing the cells has drawn increased support among scientists, they say, and paves the way for a stem cell bank of cord-blood derived iPSCs to advance regenerative medical research.

In a report published Jan. 20 in the journal Circulation, Johns Hopkins University stem cell biologist Elias Zambidis and his colleagues described laboratory experiments with these non-viral, human retinal iPSCs, that were created generated using the virus-free method Zambidis first reported in 2011.

“We began with stem cells taken from cord-blood, which have fewer acquired mutations and little, if any, epigenetic memory, which cells accumulate as time goes on,” says Zambidis, associate professor of oncology and pediatrics at the Johns Hopkins Institute for Cell Engineering and the Kimmel Cancer Center. The scientists converted these cells to a status last experienced when they were part of six-day-old embryos.

Instead of using viruses to deliver a gene package to the cells to turn on processes that convert the cells back to stem cell states, Zambidis and his team used plasmids, which are rings of DNA that replicate briefly inside cells and then are degraded and disappear.

Next, the scientists identified and isolated high-quality, multipotent, vascular stem cells that resulted from the differentiation of these iPSC that can differentiate into the types of blood vessel-rich tissues that can repair retinas and other human tissues as well. They identified these cells by looking for cell surface proteins called CD31 and CD146. Zambidis says that they were able to create twice as many well-functioning vascular stem cells as compared with iPSCs made with other methods, and, “more importantly these cells engrafted and integrated into functioning blood vessels in damaged mouse retina.”

Working with Gerard Lutty, Ph.D., and his team at Johns Hopkins’ Wilmer Eye Institute, Zambidis’ team injected these newly iPSC-derived vascular progenitors into mice with damaged retinas (the light-sensitive part of the eyeball). The cells were injected into the eye, the sinus cavity near the eye or into a tail vein. When Zamdibis and his colleagues took images of the mouse retinas, they found that the iPSC-derived vascular progenitors, regardless of injection location, engrafted and repaired blood vessel structures in the retina.

“The blood vessels enlarged like a balloon in each of the locations where the iPSCs engrafted,” says Zambidis. Their vascular progenitors made from cord blood-derived iPSCs compared very well with the ability of vascular progenitors derived from fibroblast-derived iPSCs to repair retinal damage.

Zambidis says that he has plans to conduct additional experiments in diabetic rats, whose conditions more closely resemble human vascular damage to the retina than the mouse model used for the current study, he says.

With mounting requests from other laboratories, Zambidis says he frequently shares his cord blood-derived iPSC with other scientists. “The popular belief that iPSCs therapies need to be specific to individual patients may not be the case,” says Zambidis. He points to recent success of partially matched bone marrow transplants in humans, shown to be as effective as fully matched transplants.

“Support is growing for building a large bank of iPSCs that scientists around the world can access,” says Zambidis, although large resources and intense quality-control would be needed for such a feat. However, Japanese scientists led by stem-cell pioneer Shinya Yamanaka are doing exactly that, he says, creating a bank of stem cells derived from cord-blood samples from Japanese blood banks.

Controlling Transplanted Stem Cells from the Inside Out


Scientists have worked very hard to understand how to control stem cell differentiation.  However, despite how well you direct stem cell behavior in culture, once those stem cells have been transplanted, they will often do as they wish.  Sometimes, transplanted stem cells surprise people.

Several publications describe stem cells that, once transplanted undergo “heterotropic differentiation.” Heterotropic differentiation refers to tissues that form in the wrong place. For example, one lab found that transplantation of mesenchymal stem cells into mouse hearts after a heart attack produced bone (don’t believe me – see Martin Breitbach and others, “Potential risks of bone marrow cell transplantation into infarcted hearts.” Blood 2007 110:1362-1369).  Bone in the heart – that can’t be good. Therefore, new ways to control the differentiation of cells once they have been transplanted are a desirable goal for stem cell research.

From this motivation comes a weird but wonderful paper from Jeffrey Karp and James Ankrum of Brigham and Women’s Hospital and MIT, respectively, that loads stem cells with microparticles that give the transplanted stem cell continuous cues that tell them how to behave over the course of days or weeks as the particles degrade.

“Regardless of where the cell in the body, it’s going to be receiving its cues from the inside,” said Karp. “This is a completely different strategy than the current method of placing cells onto drug-doped microcarriers or scaffolds, which is limiting because the cells need to remain in close proximity to those materials in order to function. Also these types of materials are too large to be infused into the bloodstream.”

Controlling cells in culture is relatively easy. If cells take up the right molecules, they will change their behavior. This level of control, however, is lost after the cell is transplanted. Sometimes implanted cells readily respond to the environment within the body,. but other times, their behavior is erratic and unpredictable. Karp’s strategy, which her called “particle engineering,” corrects this problem by turning cells into pre-programmable units. The internalized particles stably remain inside the transplanted cell and instruct it precisely how to act. It can direct cells to release anti-inflammatory factors, or regenerate lost tissue and heal lesions or wounds.

“Once those particles are internalized into the cells, which can take on the order of 6-24 hours, we can deliver the transplant immediately or even cryopreserve the cells,” said Karp. “When the cells are thawed at the patient’s bedside, they can be administrated and the agents will start to be released inside the cells to control differentiation, immune modulation or matrix production, for example.”

It could take more than a decade for this type of cell therapy to be a common medical practice, but to speed up the pace of this research, Karp published the study to encourage others in the scientific community to apply the technique to their various fields. Karp’s paper also illustrates the range of different cell types that can be controlled by particle engineering, including stem cells, cells of the immune system, and pancreatic cells.

“With this versatile platform, which leveraged Harvard and MIT experts in drug delivery, cell engineering, and biology, we’ve demonstrated the ability to track cells in the body, control stem cell differentiation, and even change the way cells interact with immune cells, said Ankrum, who is a former graduate student in Karp’s laboratory. “We’re excited to see what applications other researchers will imagine using this platform.”

Stem Cell-Based Gene Therapy Restores Normal Skin Function


Michele De Luca from the University of Modena, Italy and his collaborator Reggio Emilia have used a stem cell-based gene therapy to treat an inherited skin disorder.

Epidermolysis bullosa is a painful skin disorder that causes the skin to be very fragile and blister easily. These blisters can lead to life-threatening infections. Unfortunately, no cure exists for this condition and most treatments try to alleviate the symptoms and infections.

Stem cell-based therapy seems to be one of the best ways to treat this disease, there are no clinical studies that have examined the long-term outcomes of such a treatment.

However, De Luca and his colleagues have examined a particular patients with epidermolysis bullosa who was treated with a stem cell-based gene therapy nearly seven years ago as part of a clinical trial.

The treatment of this patient has established that transplantation of a small quantity of stem cells into the skin on this patient’s legs restored normal skin function without causing any adverse side effects.

“These findings pave the way for the future safe use of epidermal stem cells for combined cell and gene therapy of epidermolysis bullosa and other genetic skin diseases,” said Michele De Luca.

De Luca and his research team found that their treatment of their patient, named Claudio, caused the skin covering his upper legs to looker normal and show no signs of blisters. To treat Claudio, De Luca and his colleague extracted skin cells from Claudio’s palm, used genetic engineering techniques to correct the genetic defect in the cells, and then transplanted these cells back into the skin of his upper legs. This was part of a clinical trial conducted at the University of Modena.

Claudio’s legs also showed no signs of tumors and the small number of transplanted cells sufficiently repaired Claudio’s skin long-term. Keep in mind that Claudio’s skin cells had undergone approximately 80 cycles of cell division and still had many of the features of palm skin cells, they show proper elasticity and strength and did not blister.

“This finding suggests that adult stem cell primarily regenerate the tissue in which they normally reside, with little plasticity to regenerate other tissues,” De Luca said. “This calls into question the supposed plasticity of adult stem cells and highlights the need to carefully chose the right type of stem cell for therapeutic tissue regeneration.”

I think De Luca slightly overstates his case here. Certainly choosing the right stem cells is crucial for successful stem cell treatments, but to take stem cells from skin, which are dedicated to making skin and expect them to form other tissues is unreasonable. However, several experiments have shown that stem cells from hair follicles and form neural tissues and several other cell types as well (see Jaks V, Kasper M, ToftgĂĄrd R. The hair follicle-a stem cell zoo. Exp Cell Res. 2010 May 1;316(8):1422-8).

Adult stem cells have limited plasticity to be sure, but their plasticity is far greater than originally thought and a wealth of experiments have established that.

Despite these quibbles, this is a remarkable experiment that illustrates the feasibility and safety of such a treatment.  A larger problem is that large quantities of cells will be required to treat a person.  It is doubtful that small skin biopsies around the body can provide enough cells to treat the whole person.  Therefore, this might a case for induced pluripotent skin cells, which seriously complicates this treatment strategy.

New Tool for Stem Cell Transplantation into the Heart


Researchers from the famed Mayo Clinic, in collaboration with scientists at a biopharmaceutical biotechnology company in Belgium have invented a specialized catheter for transplanting stem cells into a beating heart.

This new device contains a curved needle with graded openings along the shaft of the needle. The cells are released into the needle and out through the openings in the side of the needle shaft. This results in maximum retention of implanted stem cells to repair the heart.

“Although biotherapies are increasingly more sophisticated, the tools for delivering regenerative therapies demonstrate a limited capacity in achieving high cell retention in the heart,” said Atta Behfar, the lead author of this study and a cardiologist. “Retention of cells is, of course, crucial to an effective, practical therapy.”

Researchers from the Mayo Clinic Center for Regenerative Medicine in Rochester, MN and Cardio3 Biosciences in Mont-Saint-Guibert, Belgium, collaborated to develop the device. Development of this technology began by modeling the dynamic motions of the heart in a computer model. Once the Belgium group had refined this computer model, the model was tested in North America for safety and retention efficiency.

These experiments showed that the new, curved design of the catheter eliminates backflow and minimizes cell loss. The graded holes that go from small to large diameters decrease the pressures in the heart and this helps properly target the cells. This new design works well in healthy and damaged hearts.

Clinical trials are already testing this new catheter. In Europe, the CHART-1 clinical trial is presently underway, and this is the first phase 3 trial to examine the regeneration of heart muscle in heart attack patients.

These particular studies are the culmination of years of basic science research at Mayo Clinic and earlier clinical studies with Cardio3 BioSciences and Cardiovascular Centre in Aalst, Belgium, which were conducted between 2009 and 2010.  This study, the C-CURE or Cardiopoietic stem Cell therapy in heart failURE study examined 47 patients, (15 control and 32 experimental) who received injections of bone marrow-derived mesenchymal stem cells from their own bone marrow into their heart muscle.  Control patients only received standard care.  After six months, those patients who received the stem cell treatment showed an increase in heart function and the distance they could walk in six minutes.   No adverse effects were observed in the stem cell recipients.

This study established the efficacy of mesenchymal stem cell treatments in heart attack patients.  However, other animal and computer studies established the efficacy of this new catheter for injecting heart muscle with stem cells.  Hopefully, the results of the CHART-1 study will be available soon.

Postscript:  The CHART-2 clinical trial is also starting.  See this video about it.

Stem Cells Treat Babies With Brittle Bone Disease While Still in the Womb


A new study published by the journal STEM CELLS Translational Medicine shows that stem cells can be effective in treating brittle bone disease, a debilitating and sometimes lethal genetic disorder.

Also known as osteogenesis imperfecta (OI), this genetic disorder was popularized by actor Samuel T. Jackson in the Bruce Willis movie “Unbreakable.” OI is characterized by fragile bones that cause patients to suffer hundreds of fractures over the course of a lifetime. According to the OI Foundation, other symptoms include muscle weakness, hearing loss, fatigue, joint laxity, curved bones, scoliosis, brittle teeth and short stature. In the more severe cases of OI, restrictive pulmonary disease also occurs. Unfortunately, to date no cure exists for OI.

Physicians use ultrasound to detect OI in babies before they are born. In this study, an international research team treated two patients for the disease with mesenchymal stem cells (MSCs) while the infants were still in the womb. After they were born, the babies were given additional mesenchymal stem cell treatments.

“We had previously reported on the prenatal transplantation for the patient with OI type III, which is the most severe form in children who survive the neonatal period,”said Cecilia Götherström, Ph.D., of the Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden. She and Jerry Chan, M.D., Ph.D., of the Yong Loo Lin School of Medicine and National University of Singapore, and KK Women’s and Children’s Hospital, led the study that also included colleagues from the United States, Canada, Taiwan and Australia.

“The first eight years after the prenatal transplant, our patient did well and grew at an acceptable rate. However, she then began to experience multiple complications, including fractures, scoliosis and reduction in growth, so the decision was made to give her another MSC infusion. In the two years since, she has not suffered any more fractures and improved her growth. She was even able to start dance classes, increase her participation in gymnastics at school and play modified indoor hockey,”Dr. Götherström added.

The second child suffered from a milder form of OI and received a stem cell transfusion 31 weeks into gestation and did not suffer any new fractures for the remainder of the pregnancy or during infancy. She followed her normal growth pattern — just under the third percentile in height, but when she was 13 months old, she stopped growing. Six months later, the doctors gave her another infusion of stem cells and she resumed growing at her previous rate.

“Our findings suggest that prenatal transplantation of autologous stem cells in OI appears safe and is of likely clinical benefit and that re-transplantation with same-donor cells is feasible. However, the limited experience to date means that it is not possible to be conclusive, for which further studies are required,”Dr. Chan said.

“Although the findings are preliminary, this report is encouraging in suggesting that prenatal transplantation may be a safe and effective treatment for this condition,”said Anthony Atala, M.D., editor of STEM CELLS Translational Medicine and director of the Wake Forest Institute for Regenerative Medicine.

Umbilical Cord Blood Stem Cells in a Biodegradable Scaffold Regenerate Full-Thickness Skin Defects


In a new study published in the ASAIO Journal by Reza Zeinali and others in the laboratory of Kamal Asadipour, specific stem cell from umbilical cord blood called unrestricted somatic stem cells (USSCs) have been grown on a biodegradable scaffold to promote skin regeneration and wound healing.

USSCs are considered by many stem cell scientists to be a type of mesenchymal stem cell, but USSCs can be grown in the laboratory and have the ability to differentiate into a wide variety of adult cell types.

Asadipour and others used a material called PHBV or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) to make a skin-like scaffold upon which the USSCs were grown. They discovered that attaching a molecule called “chitosan” to the PHBV made it quite resilient and a very good substrate for growing cells. When grown on these scaffolds, the USSCs adhered nicely to them and grew robustly.

Then Zeinali and his colleagues used these cell-impregnated scaffolds to treat open surgical wounds in laboratory rodents. After three weeks, the group treated with the cell grown on the scaffolds healed significantly better than those animals treated with just cells, just scaffolds, or neither.

Thus it seems likely that tissue-engineered skin made from modified PHBV scaffolds and embedded umbilical cord blood-based stem cells might be a potent treatment for wound patients with large injuries that do heal slowly.  In the words of the abstract of this paper, “These data suggest that chitosan-modified PHBV scaffold loaded with CB-derived USSCs could significantly contribute to wound repair and be potentially used in the tissue engineering.”

Some larger animal studies should further test this protocol and if it can augment the healing of large animal wounds, then human clinical trials should be considered.

A Patient’s Own Bone Marrow Stem Cells Defeat Drug-Resistant Tuberculosis


People infected with multidrug-resistant forms of tuberculosis could, potentially, be treated with stem cells from their own bone marrow. Even though this treatment is in the early stage of its development, the results of an early-stage trial of the technique show immense promise.

British and Swedish scientists have tested this procedure, which could introduce a new treatment strategy for the estimated 450,000 people worldwide who have multi drug-resistant (MDR) or extensively drug-resistant (XDR) TB.

This study, which was published in the medical journal, The Lancet, showed that over half of 30 drug-resistant TB patients treated with a transfusion of their own bone marrow stem cells were cured of the disease after six months.

“The results … show that the current challenges and difficulties of treating MDR-TB are not insurmountable, and they bring a unique opportunity with a fresh solution to treat hundreds of thousands of people who die unnecessarily,” said TB expert Alimuddin Zumla at University College London, who co-led the study.

TB initially infects the lungs but can rapidly spread from one person to another through coughing and sneezing. Despite its modern-day resurgence, TB is often regarded as a disease of the past. However, recently, drug-resistant strains of Mycobacterium tuberculosis, the microorganism that causes TB, have spread globally, rendering standard anti-TB drug treatments obsolete.

The World Health Organisation (WHO) estimates that in Eastern Europe, Asia and South Africa 450,000 people have MDR-TB, and close to half of these cases will fail to respond to existing treatments.

Mycobacterium tuberculosis, otherwise known as the “tubercle bacillus, trigger a characteristic inflammatory response (granulomatous response) in the surrounding lung tissue that elicits tissue damage (caseation necrosis).

Bone-marrow stem cells are known to migrate to areas of lung injury and inflammation. Upon arrival, they initiate the repair of damaged tissues. Since bone marrow stem cells also they also modify the body’s immune response, they can augment the clearance of tubercle bacilli from the body. Therefore, Zumla and his colleague, Markus Maeurer from Stockholm’s Karolinska University Hospital, wanted to test bone marrow stem cell infusions in patients with MDR-TB.

In a phase 1 trial, 30 patients with either MDR or XDR TB aged between 21 and 65 who were receiving standard TB antibiotic treatment were also given an infusion of around 10 million of their own bone marrow-derived stem cells.

The cells were obtained from the patient’s own bone marrow by means of a bone marrow aspiration, and then grown into large numbers in the laboratory before being re-transfused into the same patient.

During six months of follow-up, Zumla and his team found that the infusion treatment was generally safe and well tolerated, and no serious side effects were observed. The most common non-serious side effects were high cholesterol levels, nausea, low white blood cell counts and diarrhea.

Although a phase 1 trial is primarily designed only to test a treatment’s safety, the scientists said further analyses of the results showed that 16 patients treated with stem cells were deemed cured at 18 months compared with only five of 30 TB patients not treated with their own stem cells.

Maeurer stressed that further trials with more patients and longer follow-up were needed to better establish how safe and effective the stem cell treatment was.

But if future tests were successful, he said, this could become a viable extra new treatment for patients with MDR-TB who do not respond to conventional drug treatment or for those patients with severe lung damage.