Mesenchymal stem cells and multipotent adult progenitor cells (MAPCs) have received a good deal of discussion by scientists as agent for solid organ transplant recipients. Why? Because these cells, with their ability to suppress unwanted immune responses might be able to reduce the need for drugs that suppress the immune system, which have extensive side effects.
The study under discussion today is the clinical course of the first patient of the phase I, dose-escalation safety and feasibility study, MiSOT-I (Mesenchymal Stem Cells in Solid Organ Transplantation Phase I).
The patient received a living-related liver graft, each patient was given one intraportal injection (injection into the portal vein) and one intravenous infusion of third-party MAPC in combination with a low-dose of an anti-tissue-rejection drug.
The results so far are still coming in, but it seems that the administration of the cells is easy and is technically feasible. How well did the patients tolerate them? Quite well it turns out. There was no evidence of acute toxicity associated with infusions of the MAPCs. Also, there was some indication that the patient’s white blood cells were less reactive to foreign substances. However, it is difficult to make definitive statements about the efficacy of this treatment at this time.
Recruitment and follow-up of participants in the MiSOT-I trial continue, and completion of the study is currently projected for autumn 2016.
In a new study published in the ASAIO Journalby 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 medical research group from Miami Miller School of Medicine has examined the safety of transendocardial stem cell injections with a patient’s own bone marrow stem cells in patients with ischemic cardiomyopathy.
Ischemic cardiomyopathy is the most common type of “dilated cardiomyopathy,” which is a fancy way of saying that the heart enlarges in its failing struggle to supply the body with blood. The enlarged heart has more heart muscle to feed with oxygen, but because the heart enlarges faster than the blood vessels remodel, large portions of the enlarged heart are left without adequate blood supply, and the result is and oxygen deficit, also known as “ischemia.” In patients with ischemic cardiomyopathy, the heart’s ability to pump blood is decreased because the heart’s main pumping chamber, the left ventricle, is enlarged, dilated and weak. Usually, heart ischemia also results from coronary artery disease and heart attacks.
The symptoms of ischemic CM include shortness of breath, swelling of the legs and feet (edema), Fatigue (feeling overly tired), inability to exercise, or carry out activities as usual, angina (chest pain or pressure that occurs with exercise or physical activity and can also occur with rest or after meals), weight gain, cough and congestion related to fluid retention, palpitations or fluttering in the chest due to abnormal heart rhythms (arrhythmia), dizziness or light-headedness, and fainting (caused by irregular heart rhythms, abnormal responses of the blood vessels during exercise, without apparent cause).
Clearly an effective regenerative treatment of ischemic cardiomyopathy (ICM) would address of the needs of some of these patients. Bone marrow transplants into the heart have been tested as treatments and the stem cells were directly injected into the heart muscle (see Williams AR, et al., Circ Res. 2011;108(7):792-796; and Losordo DW, et al., Circ Res. 2011;109(4):428-436). Both of these studies, however used mononuclear cells from bone marrow. Mononuclear cells refer to white blood cells from bone marrow and it includes a wide variety of stem cells, progenitor cells, and other mature white blood cells, but excludes red blood cells or platelets, which have no nuclei.
In order to determine if mesenchymal stem cells were also safe for this type of treatment, Alan W. Haldman and his colleagues from the laboratory of Joshua M. Hare tested 65 patients who suffered from ICM and compared injection of mesenchymal stem cells (n = 19) with placebo (n = 11) and bone marrow mononuclear cells (n = 19). Patients were followed up to one year after their procedures.
To measure serious adverse effects of the procedure, all patients were evaluated at 30 days post-procedure. Severe adverse effects includes death, heart attack, stroke, hospitalization for worsening heart failure, perforation of rupture of the heart, tamponade (compression of the heart due to a collection of fluid around it), or sustained ventricular arrhythmias.
None of the patients in this study showed any severe adverse events up to day 30, and up to 1 year after the procedure, 31.6% of the bone marrow mononuclear and mesenchymal stem cell groups had some sort of serious adverse event, and 38.1% of the placebo group had serious adverse events.
Over one year, the Minnesota Living with Heart Failure score, which is a measure of the quality of life of a heart patient, improved with the mesenchymal stem cell and bone marrow cells but not with the placebo. Also, the 6-minute walk distance increased in the mesenchymal stem cell group, but none of the other groups when the baseline time was compared with the six-month and 12-month trials.
Also, the size of the heart scar showed greater shrinkage in the mesenchymal stem cell group than in the other groups.
And if a more visual way to view this would help, here is the heart of one particular patient. Notice the shrinkage in the red area, which represents the scarred area, after one year.
The authors concluded from this study that these “results provide the basis for larger studies to provide definitive assessment of safety and to assess efficacy of this new therapeutic approach.” Mesenchymal stem cells might certainly provide a way to treat ICM patients. Also, if the patient’s bone marrow is of poor quality as a result of their poor health, then mesenchymal stem cells from a donor might provide healing for these patients. For now, I say, “bring on the larger trials!!”
Occasionally. vaginal birth can lead to injury in the mother. Some of these injuries are relatively light and the mother heals rather quickly, but others can be more severe. Stress urinary incontinence (SUI) affects 4-35% of women who have given birth via vaginal delivery. SUI causes unintentional leakage from the bladder during heavy exercise, laughter, coughing, sneezing, heavy lifting, or jumping. SUI can cause discomfort, embarrassment, and some degree of social isolation. Unfortunately the treatments for SUI range from surgery to physiotherapy and they do little good.
In order to provide better options for mothers, researchers at the Cleveland Clinic’s Department of Biomedical Engineering have used female rats with birth-induced injuries as a model system. In this model system, injections of mesenchymal stem cells improved recovery from childbirth-induced injuries.
Previous work by this research group showed that injected mesenchymal stem cells tended to move into the spleen. However, if the urethra and vagina were damaged by childbirth trauma prior to mesenchymal stem cell injections, the cells targeted the damaged tissues and secreted trophic factors, which stimulated the differentiation and survival of remaining cells, and also induced the mesenchymal stem cells to engraft into the smooth muscles around the urethra and vagina. These activities accelerated and improved recovery of the animals from SUI.
Margot S. Damaser from the Cleveland Clinic said, “Stem cell-based therapy has recently gained attention as a promising treatment for SUI. Stem cell therapies may be more feasible and less invasive than current therapies.”
Other kinds of stem cells have been used to experimentally treat SUI in laboratory animals. Autologous or self-donated muscle stem cells have been used to treat SUI in animals and in human clinical trials. Fat-based stem cells have also been used, but only in animal models.
Damaser believes that mesenchymal stem cells have the added advantage of not being recognized by the immune system and therefore the possibility to implanting stem cells from an unrelated donor is a possibility for older patients.
“Since rat MSCs were used in this study, the results can only be applied to rat models of injury-treated rats,: said Damaser. “Human adult stem cells need to be investigated in future studies to see if these findings also apply to humans.”
Other researchers think that this procedure might serve as a treatment for SUI in older women. “This study provides evidence that mesenchymal stem cell transplantation could favorably impact a side effect of delivery and aging by releasing factors that can influence the urethra and vagina to treat stress urinary incontinence,” said Amit N Patel, director of cardiovascular regenerative medicine at the University of Utah. “Further studies are required to confirm that this animal study translates to humans.”
The gums are also known as the gingivae, and this soft tissue serves as a biological barrier that covers the oral cavity of the maxillae and mandible (upper and lower jawbones). The gingivae also harbor a stem cell population known as gingival mesenchymal stem cells or GMSCs.
“Oh that’s a big surprise,” you say, “another mesenchymal stem cell population found in the body.” Well this one is a big deal because of its tissue of origin. Most MSCs are formed during embryonic development from cells that originate from the mesoderm, the embryonic tissue that lies between the skin of the embryo and the gut. Mesoderm forms the muscles, bones, connective tissue, adrenal glands, circulatory system, kidneys, gonads, and some other vitally important tissues.
However, in the head, a large number of tissues are formed from “neural crest cells.” Neural crest cells hail from the top of the neural tube, which is the beginnings of the spinal cord. The dorsal-most portion of the neural tube contains a population of cells that move out of the neural tube and colonize the embryo to form a whole host of tissues. These include: Neurons, including sensory ganglia, sympathetic and parasympathetic ganglia, and plexuses, Neuroglial cells, Schwann cells, Adrenal medulla, Calcitonin-secreting cells, Carotid body type I cells, Epidermal pigment cells, Facial cartilage and bone Facial and anterior ventral skull cartilage and bones, Corneal endothelium and stroma, Tooth papillae, Dermis, smooth muscle, and adipose tissue of skin of head and neck, Connective tissue of salivary, lachrymal, thymus, thyroid, and pituitary glands, Connective tissue and smooth muscle in arteries of aortic arch origin. Wow, that’s a lot of stuff. I think you can see that these neural crest cells are important players during embryonic development.
Songtao Shi, from the Ostrow School of Dentistry, University of Southern California and his co-workers demonstrated that approximately 90% of GMSCs are derived from cranial neural crest cells and 10% are derived from mesoderm. This is important because neural crest-based stem cells seem to have greater plasticity.
Shi and his team compared mesodermally derived MSCs with GMSCs and the neural crest derived MSCs have a greater ability to differentiate into neural cells and cartilage-making cells.
In a mouse model of colitis in which mice are fed dextran sulfate sodium, which induces colitis in the mice, the neural crest derived MSCs did a better job of relieving the inflammation associated with colitis than their mesodermally derived counterparts.
Shi admits that further research on these stem cells must be done in order to better understand them and their functional roles. Shi is especially interested in the functional interaction between the neural crest derived MSCs in the gum and the mesodermally derived MSCs. Also, their potential for suppressing inflammation in particular diseases of the immune system and wound healing needs to be examined in some detail.
The umbilical cord contains a major umbilical vein and an umbilical artery, but these blood vessels are embedded in a gel-like matrix called “Wharton’s jelly.” Wharton’s jelly is home to a population of mesenchymal stem cells that have peculiar properties.
You might first say, “what on earth is a mesenchymal stem cell?” Fair enough. Mesenchymal stem cells were first discovered in bone marrow. In bone marrow, mesenchymal stem cells (MSCs) do not make blood cells; that;’s the job of the hematopoietic stem cells (HSCs). MSCs in bone marrow serve an important support role for HSCs in bone marrow. Traditionally, MSCs have the capacity to differentiate into fat cells, bone cells, and cartilage cells. However, further has shown that MSCs can also form a variety of other cell types as well if manipulated in the laboratory. MSCs also express are characteristic cadre of cell surface proteins (CD10, CD13, CD29, CD44, CD90, and CD105 for those who are interested).
MSCs, however, are found in more places that just bone marrow. As it turns out, MSCs have been found in fat, muscle, liver, tendons, synovial membrane (the membranes that surround joints, skin, and so on. Some scientists think that every organ in the body may harbor a MSC population. Furthermore, these MSC populations differ in the genes they express, their capability to differentiate into different cell types, and their cell surface proteins (see this article on this website for a rather exhaustive foray into this topic).
Now that you are more savvy about MSCs, Wharton’s jelly contains a MSC population, but this population seems to have a younger profile than MSCs from other parts of the body. They are more plastic and more invisible to the immune system than other types of MSCs. For that reason, they might be good candidates for treating a sick heart after a heart attack. A recent paper by Wei Zhang and others from the TEDA International Cardiovascular Hospital and the Tianjin Medical Cardiovascular Clinical College examined the ability of MSCs from the Wharton’s jelly of human umbilical cords to heal the hearts of minipigs after a heart attack. Oh, before I forget – this paper was published in the journal Coronary Artery Disease.
Twenty-three minipigs were subjected to open-heart surgery and given heart attacks. Then the pigs were divided into three groups, a control group, a group that received injections of saline into their hearts, and a third group that received injections of 40 million human Wharton’s jelly derived MSCs into the region of the infarct. The animals were sewn up and given antibiotics to prevent infection.
Six weeks after surgery, each animal was examined by means of Technetium-sestamibi myocardial perfusion imaging, and electrocardiography. For those who do not know what Technetium-sestamibi myocardial perfusion imaging is for, it works like this. Cardiolite is the trade name of a large, fat-soluble molecule that flows through the heart in a fashion proportion to the blood flow through the heart muscle. Single photon emission computed tomography or SPECT is used to detect the Cardiolite. Areas of the heart without blood flow are the regions damaged during the heart attack. Therefore, this technique is extremely useful to determine the area of damage in the heart.
After the animals were examined, they were put down and their hearts were extracted, sectioned, and stained for areas or cell death, and the areas where the injected stem cells resided. All injected stem cells were labeled before injection so that they were easily detectable.
The results were clear. The heart injected with MSCs from umbilical cord did not show any decrease in ejection fraction, whereas the other two groups showed an average reduction in injection fraction of around 10%. In fact the stem cell-injected hearts showed an average 1 % increase in ejection fraction. The blood flow in the hearts was even more different. blood flow is measured as a ratio of dead heart tissue to total heart tissue. The control of saline-injected hearts had an average ratio of about 4%, whereas the stem cell-injected hearts had a slightly negative percentage. This is a significant difference. Echocardiography confirmed that the wall thickness of the stem cell-injected hearts was significantly thicker than the walls of the control or the saline-injected hearts; some 14 times thicker!!
When the dissected hearts were examined, the MSC-injected hearts had lots of stem cells still in them. The cells not only survived, but, according to Zhang and his colleagues, differentiated into heart muscle cells. Their rationale for this conclusion is three-fold – the cells had the same shape and form or native heart muscle cells, they expressed heart specific Troponin T and vWF proteins, and electrically coupled with other heart muscle cells by expressing connexin. Connexin is a protein that traverses the membranes of two closely apposed cells and forms small pores between two cells that allows the exchange of SMALL molecules such as ions, ATP, and things like that. These connexin constructed pores are called “gap junctions” and they are the reason heart muscle cells work as a single unit, since any electrochemical change in one cell immediately spreads to all other nearby, connected cells.
As much as I would like to believe Zhang and his colleagues, I remain skeptical that these cells differentiated into heart muscle cells. I say this because MSCs can be differentiated in culture to form cells that look and act like heart muscle cells. These cells will even express some heart-specific genes. However, they lack the calcium handling machinery of true heart muscle cells and do not function as true heart muscle. To convince that these Wharton jelly MSCs truly are heart muscle cells, they will need to show that they contain heart specific calcium handling proteins (see Shake JG, Gruber PJ, Baumgartner WA et al. Ann Thorac Surg 2002;73:1919–1925; Davani S, Marandin A, Mersin N et al. Circulation 2003;108(suppl 1):II253–258; Hou M, Yang KM, Zhang H et al. Int J Cardiol 2007;115:220 –228). If they can show this, then I will believe them.
However, there are two findings of this paper that are not in doubt. The number of blood vessels in the hearts of the MSC-treated animals far exceeded the number found in the control or the saline-treated hearts (3-4 times the number of blood vessels). Therefore, the Wharton’s jelly MSCs induced lots and lots of blood vessels. Many of these blood vessels contained labeled cells, which shows that the MSCs differentiated into endothelial and smooth muscle cells, Also, the Wharton’s jelly MSCs clearly induced resident cardiac stem cell (CSC) populations in the hearts of the minipigs, since several cells that expressed CSC surface molecules were found in the heart muscle tissue. Previous work by Hatzistergos and others showed that MSCs induce the endogenous CSC population and this is one of the ways that MSCs help heal ailing hearts (Circulation Research 2010 107:913-22).
Zhang’s paper is interesting and it shows that Wharton’s jelly MSCs are safe and efficacious for treating the heart after a heart attack. Also, none of the minipigs in this experiment were treated with drugs to suppress the immune system. No immune response against the cells was reported. Therefore, the invisibility of these cells to the immune system seems to last, at least in this experiment.
If you are exposed to high local doses of radiation, your skin will burn and undergo very slow healing. Your skin will also experience a great deal of cell death, and high levels of cell death within a tissue cause a condition called necrosis. High levels of local radiation, which cause painful necrosis, slow healing and a delayed outcome, are characteristics of “cutaneous radiation syndrome.”
Recently, work on cutaneous therapeutic management of patients with cutaneous radiation syndrome has strongly suggested that such burn patients would benefit from stem cell treatments with mesenchymal stem cells. A paper from the laboratory of Michel Drouet, who is a member of the Radiology Department at the Institut de Recherche Biomédicale des Armées in La Tronche, France has examined such a treatment strategy in pigs.
Diane Riccobono and her colleagues compared the effectiveness of an animal’s own stem cells with the effectiveness of borrowed stem cells from another unrelated animal. They used minipigs for these experiments, and the animals were exposed to about 50 Grays of radiation, which is about the radiation dose someone would receive for radiation therapy. The animals were divided into three groups.
One group was engrafted with their own fat-based mesenchymal stem cell (5 animals in this group). The second group was engrafted with fat-based mesenchymal stem cells from another animals (5 animals in this group too). Animals received fat-based mesenchymal stem cells four times after receiving their dose of radiation. A third group consisting of eight animals received culture media but no cells.
All the pigs were examined and scored according to the severity of their wounds. The control animals showed local inflammatory that led to persistent painful necrosis. Since this display is very similar to what is observed in human patients with cutaneous radiation syndrome, it gave Riccobono and her colleagues a great deal of confidence that this animal model nicely mimics the clinical progression of this disease in human patients. Also, the clinical outcome was not significantly different in the animals treated with fat-based mesenchymal stem cells from another unrelated animal. These animals showed skin healing without necrosis, and the animals suffered from uncontrollable pain, much like the controls. However, in the animals engrafted with fat-based stem cells from their own bodies, the radiation wounds healed without necrosis. Furthermore, healing also did not progress to uncontrollable pain.
This study seems to show that stem cell grafting with fat-based stem cells a patient’s own body improves healing in patients with cutaneous radiation syndrome. However, fat-based mesenchymal stem cells from unrelated animals do not facilitate such healing. Can manipulation of allogeneic stem cells improve their therapeutic potential? Only further work will tell.
See Riccobono D, Agay D, Scherthan H, Forcheron F, Vivier M, Ballester B, Meineke V, Drouet M.., Application of adipocyte-derived stem cells in treatment of cutaneous radiation syndrome. Health Phys. 2012 Aug;103(2):120-6.