My goal as a regenerative medicine physician is to know what research backs up the various treatments that I offer to patients. And actually it is more than just a goal, it is my duty to know. If I cannot find some evidence that a therapy is beneficial, then I shouldn't be doing it. As a doctor, I am responsible for being informed and only offering safe and efficacious solutions for my patients.
This blog is my effort to compile the data that I find into an easy-to-understand synopsis for patients looking to educate themselves. The intent is to summarize the research and give an educated opinion about it. And many of these blogs stem directly from questions that patients have asked me.
Along that line, I receive many inquiries into cellular therapies, including platelet-rich plasma (PRP) and stem cells. These 2 techniques involve using a patient's own cells to elicit a healing response within their own body. They are very safe as there are no foreign substances used, no pharmaceuticals, no implants. But there is some question as to which is better, or in what circumstances to use one therapy over the other.
Obtaining PRP is relatively simple, involving only a blood draw from the patient. The blood is then put through a series of spins in a centrifuge in order to obtain a highly concentrated sample of platelets and growth factors within the plasma. This liquid product can then be injected into a joint, tendon, ligament, muscle, or the like, in order to help facilitate healing and pain relief. There is rarely any downtime, and only minimal side effects associated with it.
Obtaining stem cells is a bit more involved, requiring a minor procedure to obtain either fat cells through manual liposuction or occasionally bone marrow via a bone marrow harvest. These both require incisions and some post-operative care due to the fact that these are both more invasive than just obtaining blood. Also, the process involved in isolating the stem cells is more complex and time-consuming. This directly relates to more expense for the patient.
Given these factors, using PRP tends to be the first recommendation for many patients. Obviously this depends on each patient and the specific medical issue being addressed. That being said, the benefits associated with PRP along with the low risk and ease of obtaining and preparing the sample make this an ideal first therapeutic option. Also, the monetary cost to the patient is much less when compared to a stem cell procedure. There are some situations however, where PRP may not be appropriate. Again, the decision must be made after careful consideration between you and your physician. Learn the pros and cons of each and ask questions. The final choice will ultimately depend on your specific circumstances.
Friday, December 15, 2017
Friday, May 12, 2017
More Research with Stem Cells and Multiple Sclerosis
A recent study (JAMA Neurol. 2017; 74(4):459-469) by Paolo Muraro, et al. looks at long-term results of stem cell therapy on multiple sclerosis (MS). This study followed 281 MS patients with predominantly progressive forms of the disease that were not responding to standard therapies. These patients received autologous hematopoietic stem cell transplants between 1995 and 2006 (meaning that the stem cells were taken from their own peripheral blood).
The observational data was collected from 25 different medical facilities in 13 countries, with 77% of the patients exhibiting progressive forms of MS and median follow-up was 6.6 years. Multiple factors were looked at in this study, including age, number of prior disease-modifying treatments, disease sub-type/severity, baseline Expanded Disability Status Scale (EDSS) score, and the overall intensity of conditioning regimen and graft manipulation. The primary outcomes were both MS progression-free survival and overall survival.
Out of the 281 patients, 8 died within the first 100 days of transplant and these were considered a transplant-related mortality of 2.8%. It is not known if these deaths were truly attributable to the stem cell therapy, but were considered for mortality based on the structure of the study.
The 5-year probability of progression-free survival was 48% and overall 5-year survival was 93%. It is remarkable that almost half of the patients remained free from neurological progression at 5 years. Better outcomes were associated with younger age (not surprising, as this has been repeatedly shown), relapsing form (vs. progressive MS), fewer previous immunotherapies, and lower baseline EDSS scores.
These findings support further studies of stem cell therapies for treatment of MS in order to delineate the exact modalities and procedures that will provide consistent and beneficial results. Once again, stem cells seem to be a key link in the future of medicine and treatment of difficult disease processes.
The observational data was collected from 25 different medical facilities in 13 countries, with 77% of the patients exhibiting progressive forms of MS and median follow-up was 6.6 years. Multiple factors were looked at in this study, including age, number of prior disease-modifying treatments, disease sub-type/severity, baseline Expanded Disability Status Scale (EDSS) score, and the overall intensity of conditioning regimen and graft manipulation. The primary outcomes were both MS progression-free survival and overall survival.
Out of the 281 patients, 8 died within the first 100 days of transplant and these were considered a transplant-related mortality of 2.8%. It is not known if these deaths were truly attributable to the stem cell therapy, but were considered for mortality based on the structure of the study.
The 5-year probability of progression-free survival was 48% and overall 5-year survival was 93%. It is remarkable that almost half of the patients remained free from neurological progression at 5 years. Better outcomes were associated with younger age (not surprising, as this has been repeatedly shown), relapsing form (vs. progressive MS), fewer previous immunotherapies, and lower baseline EDSS scores.
These findings support further studies of stem cell therapies for treatment of MS in order to delineate the exact modalities and procedures that will provide consistent and beneficial results. Once again, stem cells seem to be a key link in the future of medicine and treatment of difficult disease processes.
Friday, January 20, 2017
Stem Cells Repair Teeth
Researchers at the King's College London published an interesting study in Scientific Reports wherein a novel stem cell treatment was used to self-heal tooth cavities.
The study involved the use of a molecule called Tideglusib, a kinase inhibitor that actually activates stem cells and pushes them into repair mode. This same inhibitor has also been successfully used in the treatment of Alzheimer's disease through clinical trials.
Traditionally, large cavities have been filled with a variety of substances, including porcelain, composite resin, cement, gold, and amalgams that may have mercury or silver. These types of fillings remain in the tooth indefinitely, and can break over time. This obviously then requires another filling to replace the damaged one. The reason to have fillings is that teeth cannot naturally repair large cavities on their own.
Ordinarily, our teeth heal damage by promoting the release of dentine within our bodies. Dentine is the hard, dense bony tissue of our teeth that occurs below the enamel. This natural coating helps to protect the soft pulp of our teeth. In the case of large cavities, the amount of dentine that is naturally produced is insufficient to completely heal the deficit. In addition, it appears that fillings themselves subsequently prevent normal mineral levels from being restored in the affected tooth.
The researchers in this study proposed a new treatment option that involves biodegradable collagen sponges along with Tideglusib to promote stem cell activity. The sponges help to deliver glycogen molecules into the cavity and then deteriorate over time, allowing dentine and the natural mineralization to fill in the cavity. Through this treatment modality, stem cells are signaled and attracted to the damaged area, helping to activate the natural repair mechanism.
This novel approach would diminish the need for traditional fillings and the possibility of needing those replaced in the future. Once again, our very own cells are used to heal and treat our own bodies!
The study involved the use of a molecule called Tideglusib, a kinase inhibitor that actually activates stem cells and pushes them into repair mode. This same inhibitor has also been successfully used in the treatment of Alzheimer's disease through clinical trials.
Traditionally, large cavities have been filled with a variety of substances, including porcelain, composite resin, cement, gold, and amalgams that may have mercury or silver. These types of fillings remain in the tooth indefinitely, and can break over time. This obviously then requires another filling to replace the damaged one. The reason to have fillings is that teeth cannot naturally repair large cavities on their own.
Ordinarily, our teeth heal damage by promoting the release of dentine within our bodies. Dentine is the hard, dense bony tissue of our teeth that occurs below the enamel. This natural coating helps to protect the soft pulp of our teeth. In the case of large cavities, the amount of dentine that is naturally produced is insufficient to completely heal the deficit. In addition, it appears that fillings themselves subsequently prevent normal mineral levels from being restored in the affected tooth.
The researchers in this study proposed a new treatment option that involves biodegradable collagen sponges along with Tideglusib to promote stem cell activity. The sponges help to deliver glycogen molecules into the cavity and then deteriorate over time, allowing dentine and the natural mineralization to fill in the cavity. Through this treatment modality, stem cells are signaled and attracted to the damaged area, helping to activate the natural repair mechanism.
This novel approach would diminish the need for traditional fillings and the possibility of needing those replaced in the future. Once again, our very own cells are used to heal and treat our own bodies!
Thursday, May 12, 2016
Chronic Inflammation's Effect on Stem Cells
A study published in the journal Nature Cell Biology on April 25, 2016, illuminates the detrimental impact of chronic inflammation on bone marrow stem cells. The study by Eric Pietras, PhD and his team focused on the inflammatory marker known as interleukin-1 (IL-1), a cytokine that is released in our bodies during times of stress or emergency situations. IL-1 has also been shown to be elevated in association with certain chronic disease processes such as diabetes, chronic stress, autoimmune disorders, and obesity.
IL-1 stimulates the blood-forming marrow stem cells, or hematopoietic stem cells (HSC's), to produce certain types of cells that are needed as a direct response to a crisis situation such as an injury or infection. When this occurs, these stem cells give up their ability to self-renew, thus compromising the body's normal functioning blood system. This is a normal response to short-term issues that we are confronted with, as this acute response is necessary to fight infections or repair injuries.
However, this becomes a problem in situations where the long-term stress of inflammation never stops, as mentioned in the disease states above. When the signals that lead to elevated IL-1 are constant, the HSC's keep responding as if there is an acute injury or infection, at the expense of their ability to keep the blood system in normal working order. As a result, the body may produce too few red blood cells (thus decreasing the ability to deliver needed oxygen to the body) or too few lymphoid cells (thereby leading to a potentially immunodeficient state). In these situations, the body is essentially weakened and can exacerbate other medical conditions or predispose to new injuries or infections.
The good news with the study is that these effects are only transient in nature and are reversible with the elimination of the IL-1 stimulus. The take-away message is that chronic inflammation is quite harmful and therefore necessitates the elimination of whatever is causing that state of being.
IL-1 stimulates the blood-forming marrow stem cells, or hematopoietic stem cells (HSC's), to produce certain types of cells that are needed as a direct response to a crisis situation such as an injury or infection. When this occurs, these stem cells give up their ability to self-renew, thus compromising the body's normal functioning blood system. This is a normal response to short-term issues that we are confronted with, as this acute response is necessary to fight infections or repair injuries.
However, this becomes a problem in situations where the long-term stress of inflammation never stops, as mentioned in the disease states above. When the signals that lead to elevated IL-1 are constant, the HSC's keep responding as if there is an acute injury or infection, at the expense of their ability to keep the blood system in normal working order. As a result, the body may produce too few red blood cells (thus decreasing the ability to deliver needed oxygen to the body) or too few lymphoid cells (thereby leading to a potentially immunodeficient state). In these situations, the body is essentially weakened and can exacerbate other medical conditions or predispose to new injuries or infections.
The good news with the study is that these effects are only transient in nature and are reversible with the elimination of the IL-1 stimulus. The take-away message is that chronic inflammation is quite harmful and therefore necessitates the elimination of whatever is causing that state of being.
Friday, November 13, 2015
PRP and Hair Regrowth
Platelet-rich plasma (PRP) has been shown to be an effective treatment for hair loss. I have only performed this procedure on one patient thus far, using PRP injections in conjunction with micro-needling. This patient had some success after two treatments, and will be returning for a third session in the future.
Androgenic alopecia , or male pattern hair loss, can affect up to 80% of white men and even up to 40% of women. There are multiple treatments available for this type of hair loss, although some of them will offer no benefit to many people. Minoxidil and finasteride are two of the more common drug therapies approved by the FDA. In general, finasteride will help you keep the hair you have while minoxidil has some potential to grow new hair. Laser light therapy is another option, although it appears this may help keep the hair you have but will not actually grow new hair; it also seems to be the least effective of the therapies. One of the more successful therapies is hair transplant surgery, although the success rates vary widely and this can often necessitate more than one treatment.
A recent article published in the November 2015 journal Stem Cells Translational Medicine focused on the use of PRP injections in the realm of androgenic alopecia. The research by Gentile, et al., titled "The Effect of Platelet-Rich Plasma in Hair Regrowth: A Randomized Placebo-Controlled Trial", studied the effect of PRP after 3 treatment cycles that were 30 days apart. There were 23 study participants.
The procedure used in this study was simply PRP injected into an area of the scalp containing hair follicles, along with placebo injections in order to truly evaluate the effects. No local anesthesia was used during these treatments. The results were evaluated in 6 separate stages: at the beginning of the study, then at 2 months, 6 months, 12 months, 16 months, and 24 months. These evaluations were made via photography, physician and patient assessments, and biopsies.
The results were very promising across the board. There was a significant increase in the overall hair count in the PRP treatment area after 3 months; the PRP area had 33.6 more hairs on average while the placebo region had 3.2 less hairs on average.The average density on hairs increased in the PRP treatment region by 45.9 hairs per square cm, with a 3.8 hair per square cm loss in the control area. Biopsies showed an increase in epidermal skin thickness and an increase in the overall number of hair follicles in those areas treated with PRP. Those are all very promising results from a procedure with low relative risk.
At 16 months, 4 of the 23 study patients showed some degree of progressive hair loss again. These patients were re-treated with a series of 3 PRP treatments; the results after those injections were not evaluated in this study.
This is yet another in a series of small trials studying the efficacy of PRP for treatment of hair loss. Other studies have shown similar promising results.
Here is a photo from the article referenced. This is a 29 year-old male 2 weeks after the final treatment, with both increased hair density and total hair count.
The method I have used has 2 potential ways to stimulate hair growth. The first is the injection of PRP as proposed in this research study and others like it. The other mode to potentially promote hair growth is the use of microneedling. This is a technique whereby a number of fine surgical grade microneedles are used to stimulate dermal stem cells and activate growth factors in the scalp. There have been studies also showing the effectiveness of microneedling for hair loss, and I will look at some of those results in the future.
Androgenic alopecia , or male pattern hair loss, can affect up to 80% of white men and even up to 40% of women. There are multiple treatments available for this type of hair loss, although some of them will offer no benefit to many people. Minoxidil and finasteride are two of the more common drug therapies approved by the FDA. In general, finasteride will help you keep the hair you have while minoxidil has some potential to grow new hair. Laser light therapy is another option, although it appears this may help keep the hair you have but will not actually grow new hair; it also seems to be the least effective of the therapies. One of the more successful therapies is hair transplant surgery, although the success rates vary widely and this can often necessitate more than one treatment.
A recent article published in the November 2015 journal Stem Cells Translational Medicine focused on the use of PRP injections in the realm of androgenic alopecia. The research by Gentile, et al., titled "The Effect of Platelet-Rich Plasma in Hair Regrowth: A Randomized Placebo-Controlled Trial", studied the effect of PRP after 3 treatment cycles that were 30 days apart. There were 23 study participants.
The procedure used in this study was simply PRP injected into an area of the scalp containing hair follicles, along with placebo injections in order to truly evaluate the effects. No local anesthesia was used during these treatments. The results were evaluated in 6 separate stages: at the beginning of the study, then at 2 months, 6 months, 12 months, 16 months, and 24 months. These evaluations were made via photography, physician and patient assessments, and biopsies.
The results were very promising across the board. There was a significant increase in the overall hair count in the PRP treatment area after 3 months; the PRP area had 33.6 more hairs on average while the placebo region had 3.2 less hairs on average.The average density on hairs increased in the PRP treatment region by 45.9 hairs per square cm, with a 3.8 hair per square cm loss in the control area. Biopsies showed an increase in epidermal skin thickness and an increase in the overall number of hair follicles in those areas treated with PRP. Those are all very promising results from a procedure with low relative risk.
At 16 months, 4 of the 23 study patients showed some degree of progressive hair loss again. These patients were re-treated with a series of 3 PRP treatments; the results after those injections were not evaluated in this study.
This is yet another in a series of small trials studying the efficacy of PRP for treatment of hair loss. Other studies have shown similar promising results.
Here is a photo from the article referenced. This is a 29 year-old male 2 weeks after the final treatment, with both increased hair density and total hair count.
The method I have used has 2 potential ways to stimulate hair growth. The first is the injection of PRP as proposed in this research study and others like it. The other mode to potentially promote hair growth is the use of microneedling. This is a technique whereby a number of fine surgical grade microneedles are used to stimulate dermal stem cells and activate growth factors in the scalp. There have been studies also showing the effectiveness of microneedling for hair loss, and I will look at some of those results in the future.
Tuesday, August 25, 2015
Stem Cells and Myopia
An interesting review article in the July 2015 issue of Stem Cells looks at using stem cell therapy to prevent the progression of myopia ("Concise Review: Using Stem Cells to Prevent the Progression of Myopia - A Concept", by M. Janowski, et. al.). The authors, a team from Johns Hopkins University School of Medicine, discuss the prevalence of myopia and how different mechanisms might be amenable for stem cell treatments.
Myopia, or nearsightedness, is basically the condition where objects that are near are seen clearly while far objects are blurry. There are a couple of causes, either the eyeball being too long or the cornea being overly curved. Both scenarios cause light entering the eye to not focus appropriately. This leads to the blurred vision of distant objects.
This condition is rather common, affecting about 30% of the population in the US. However, it is becoming an increasingly more common disorder throughout the world. There are both hereditary and environmental influences that lead to the condition, and as the world becomes more industrialized the environmental effect is increasing. It seems that this is due to strain on the eyes caused by educational stressors along with a decrease in sunlight exposure. In areas of the world with minimal education, the incidence is rather low; however, in those regions with more advanced educational systems the rate of myopia is rapidly increasing, possibly towards pandemic levels.
The authors propose a couple of ways in which stem cells might be useful in treatment of myopia and its progression. The first is in use of stem cells to support the sclera of the eye, as the myopic sclera is commonly characterized as being weak, thinned, and less rigid than normal. This theory is based on applying stem cells to an area in the back of the eye in a region known as the subscleral space, between the sclera and the choroid. These cells would then differentiate into fibroblasts that can produce extracellular matrix, strengthen and reinforce the sclera itself, and prevent elongation of the eyeball. In this case, the stem cells have a direct effect on the eye.
The second proposed method of treatment with stem cells is in the area of dopaminergic signaling. Dopamine is a neurotransmitter, a type of chemical produced by certain cells to send signals to other cells. There is significant cross-talk between the sclera and the retina, and a proposed cause of myopia is a disruption or dysfunction in that signaling process. Dopamine is secreted in the retina to specifically enhance the activity of cone cells while also suppressing activity of rods. This occurs only during daylight hours as a way to increase sensitivity to contrast and color during the conditions of bright light. It also seems that dopamine plays a role in the eye's growth and potentially in control of myopia. Various animal studies have already shown that dopamine and dopamine-agonists can slow myopic changes. Thus, stem cells could be used to obtain highly functional dopaminergic cells which could then be used to treat myopia. In this instance, the stem cells are contributing an indirect effect.
The take-away is that stem cell treatments could be formulated to provide both direct and indirect help for this particular medical issue. Once again, the potential applications for stem cells continues to expand!
Myopia, or nearsightedness, is basically the condition where objects that are near are seen clearly while far objects are blurry. There are a couple of causes, either the eyeball being too long or the cornea being overly curved. Both scenarios cause light entering the eye to not focus appropriately. This leads to the blurred vision of distant objects.
This condition is rather common, affecting about 30% of the population in the US. However, it is becoming an increasingly more common disorder throughout the world. There are both hereditary and environmental influences that lead to the condition, and as the world becomes more industrialized the environmental effect is increasing. It seems that this is due to strain on the eyes caused by educational stressors along with a decrease in sunlight exposure. In areas of the world with minimal education, the incidence is rather low; however, in those regions with more advanced educational systems the rate of myopia is rapidly increasing, possibly towards pandemic levels.
The authors propose a couple of ways in which stem cells might be useful in treatment of myopia and its progression. The first is in use of stem cells to support the sclera of the eye, as the myopic sclera is commonly characterized as being weak, thinned, and less rigid than normal. This theory is based on applying stem cells to an area in the back of the eye in a region known as the subscleral space, between the sclera and the choroid. These cells would then differentiate into fibroblasts that can produce extracellular matrix, strengthen and reinforce the sclera itself, and prevent elongation of the eyeball. In this case, the stem cells have a direct effect on the eye.
The second proposed method of treatment with stem cells is in the area of dopaminergic signaling. Dopamine is a neurotransmitter, a type of chemical produced by certain cells to send signals to other cells. There is significant cross-talk between the sclera and the retina, and a proposed cause of myopia is a disruption or dysfunction in that signaling process. Dopamine is secreted in the retina to specifically enhance the activity of cone cells while also suppressing activity of rods. This occurs only during daylight hours as a way to increase sensitivity to contrast and color during the conditions of bright light. It also seems that dopamine plays a role in the eye's growth and potentially in control of myopia. Various animal studies have already shown that dopamine and dopamine-agonists can slow myopic changes. Thus, stem cells could be used to obtain highly functional dopaminergic cells which could then be used to treat myopia. In this instance, the stem cells are contributing an indirect effect.
The take-away is that stem cell treatments could be formulated to provide both direct and indirect help for this particular medical issue. Once again, the potential applications for stem cells continues to expand!
Tuesday, May 12, 2015
Tissue Repair Mechanisms by Stem Cells
The complete picture on how stem cells actually repair damaged tissue has yet to be fully defined. There are a number of studied mechanisms, and it is most likely that there are a multitude of events that take place during this treatment process, and it is the combination of modalities that leads to repair success.
The original theory was that injected stem cells would directly change, or differentiate, into new tissue cells. These new tissue cells were thought to be the actual injected stem cells that had turned into whatever cells the body needed at the site of injury. This has shown to be part of the overall picture, but not as much as initially thought.
A great article from 2010 studied human stem cells in mice that had experienced cardiac injury (I. Chimenti, R. R. Smith, et al., "Relative Roles of Direct Regeneration Versus Paracrine Effects of Human Cardiosphere-Derived Cells Transplanted Into Infarcted Mice", Circulation Research, Vol. 106, No. 5, pp.971-980, 2010). This study demonstrated a contribution from differentiating stem cells along with the release of certain growth factors and beneficial molecules. The authors concluded that differentiation only accounted for 20-50% of the repair process. Stem cell released molecules such as growth factors, antioxidants, and anti-inflammatory factors actually seem to play a more important role. All of these substances together help to promote the proliferation of cells, the migration of existing stem cells, and the boosting of the immune system. The researchers claimed that these mechanisms accounted for 50-80% of the repair mechanism.
In addition, when stem cells are given systemically (such as through an IV), multiple studies have shown that only a small portion of the stem cells end up at the site of injury or disease. The majority end up scattered throughout the body, and the lifespan of these cells seems to be less than originally thought. This supports the idea that other factors are involved in the repair process, not just stem cells changing into normal, healthy tissue cells.
In addition to the large array of growth factors that help with the repair process, it appears that other mechanisms also play some role. A study by J. Spees, M. Whitney, et al. elucidated the role in mitochondrial transfer between stem cells and existing damaged cells ("Mitochondrial transfer between cells can rescue aerobic respiration", Proceedings of the National Academy of Sciences of the USA, Vol. 103, No. 5, pp. 1283-1288, 2006). Our mitochondria are responsible for the life of our cells, and there a variety of reasons why the mitochondria will not function properly. This can occur in certain disease states, with advancing age, and with injury to tissues. This study showed that stem cells can transfer mitochondrial DNA into damaged cells and thus rescue them from death.
Fusion of two cells may also play a role in this scenario, as a stem cell may fuse with an existing cell, again transferring genetic material and rescuing the cell from death. This has been shown in more than one study, including a more recent set of studies edited by T. Dittmar and K. Zanker titled "Cell Fusion in Health and Disease", released in 2011.
These are just some of the mechanisms that appear to play a part in the healing effects of stem cells. Research is ongoing and time will give us many more answers (and most likely, more questions as well). Stay tuned for more....
The original theory was that injected stem cells would directly change, or differentiate, into new tissue cells. These new tissue cells were thought to be the actual injected stem cells that had turned into whatever cells the body needed at the site of injury. This has shown to be part of the overall picture, but not as much as initially thought.
A great article from 2010 studied human stem cells in mice that had experienced cardiac injury (I. Chimenti, R. R. Smith, et al., "Relative Roles of Direct Regeneration Versus Paracrine Effects of Human Cardiosphere-Derived Cells Transplanted Into Infarcted Mice", Circulation Research, Vol. 106, No. 5, pp.971-980, 2010). This study demonstrated a contribution from differentiating stem cells along with the release of certain growth factors and beneficial molecules. The authors concluded that differentiation only accounted for 20-50% of the repair process. Stem cell released molecules such as growth factors, antioxidants, and anti-inflammatory factors actually seem to play a more important role. All of these substances together help to promote the proliferation of cells, the migration of existing stem cells, and the boosting of the immune system. The researchers claimed that these mechanisms accounted for 50-80% of the repair mechanism.
In addition, when stem cells are given systemically (such as through an IV), multiple studies have shown that only a small portion of the stem cells end up at the site of injury or disease. The majority end up scattered throughout the body, and the lifespan of these cells seems to be less than originally thought. This supports the idea that other factors are involved in the repair process, not just stem cells changing into normal, healthy tissue cells.
In addition to the large array of growth factors that help with the repair process, it appears that other mechanisms also play some role. A study by J. Spees, M. Whitney, et al. elucidated the role in mitochondrial transfer between stem cells and existing damaged cells ("Mitochondrial transfer between cells can rescue aerobic respiration", Proceedings of the National Academy of Sciences of the USA, Vol. 103, No. 5, pp. 1283-1288, 2006). Our mitochondria are responsible for the life of our cells, and there a variety of reasons why the mitochondria will not function properly. This can occur in certain disease states, with advancing age, and with injury to tissues. This study showed that stem cells can transfer mitochondrial DNA into damaged cells and thus rescue them from death.
Fusion of two cells may also play a role in this scenario, as a stem cell may fuse with an existing cell, again transferring genetic material and rescuing the cell from death. This has been shown in more than one study, including a more recent set of studies edited by T. Dittmar and K. Zanker titled "Cell Fusion in Health and Disease", released in 2011.
These are just some of the mechanisms that appear to play a part in the healing effects of stem cells. Research is ongoing and time will give us many more answers (and most likely, more questions as well). Stay tuned for more....
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