Rich Lowry at National Review has yet another take on Rick Perry’s treatment. It’s a good read.
Texas governor and Republican presidential candidate Rick Perry has received a fair amount of criticism for receiving a stem cell treatment for his back. The Rising Voice blog has another take on Perry’s treatment, which, by the way, was paid for with his own money and was his free choice to receive. Even if the procedure was somewhat experimental, Perry made his own informed decision to receive it. ll these criticism aside, some critics need to get over themselves. No one was harmed through Perry’s decision to receive this treatment, and Perry sought the treatment even though he knew it wasn’t FDA approved or endorsed. Apparently, the clinic that offered the treatment had garnered enough evidence to convince Perry, and he acquiesced to the treatment. If this inspires other people to seek similar treatments, then they will need to make their own informed decisions based on the evidence in hand. If the clinic is honest and transparent about their procedure and the evidence for it, then we should rejoice that Governor Perry received successful treatment without burdening the present health care system. That sounds like a win-win situation to me.
Scientists succeeded in making induced pluripotent stem cells in pigs (Zhao Wu, et al. Generation of Pig Induced Pluripotent Stem Cells with a Drug-Inducible System. J Mol Cell Biol 1, no. 1 (2009): 46-54). Pig iPSCs are a valuable research tool, since pig cells have a greater similarity to humans than do mouse cells. Also, pig iPSCs allow for the production of chimeric animals that are partially composed of cells descended from one cell type and also composed of cells from a different cell type. Chimeric animals that are partially made from iPSCs allow for the study of how effectively iPSCs cause tumors and other iPSC issues. This is an essential study because chimeric mice that partially consist of iPSCs showed that iPSC derived chimeras possessed large numbers of tumors. This result raises significant concerns about the safety of iPSC therapies. Additionally, pig iPSCs can generate chimeras whose gametes are made from iPSCs. This can potentially revolutionize the transgenic animal field by enabling complex genetic manipulations (e.g. knockout or knockin of genes) to produce biomedically important large animal models or improve livestock production.
In this study, Steen Stice’s research group demonstrated the germline transmission of iPSCs with the live birth of a transgenic piglet that possessed genome integration of two human genes. Additionally, gross and histological examination of necropsied porcine chimeras at 2, 7 and 9 months showed these animals lacked tumor formation and demonstrated normal development. The development of germline competent porcine iPSCs that do not produce tumors in young chimeric animals presents an attractive and powerful translational model to study the efficacy and safety of stem cell therapies and perhaps to efficiently produce complex transgenic animals.
In 2008, scientists from Thomas Jefferson University in Philadelphia, Pennsylvania and the University of Heidelberg, Germany published a study that shows the conversion of bone marrow stem cells into cells that look like heart muscle cells. They cultured rat bone marrow stem cells with heart muscle cells from baby rats and then added two growth factors that are commonly found in developing heart. These growth factors include fibroblast growth factor-2 (FGF-2) and bone morphogen protein-2 (BMP-2). They cultured the bone marrow stem cells with the baby rate heart muscle cells for ten days and added either BMP-2, FGF-2 or FGF-2 + BMP-2. Neither BMP-2 or FGF-2 alone could elicit any significant change in the bone marrow cells, but when FGF-2 and BMP-2 were added together, the caused the bone marrow stem cells to express heart muscle-specific genes.
Transformed bone marrow stem cells made transcription factors like Nkx2.5 and GATA-4. These two transcription factors are expressed in developing heart cells, and the production of these transcription factors in bone marrow stem cells demonstrates that they are differentiating into heart cells. These transformed bone marrow stem cells also produced connexion-43, which is a protein that allows calcium ions to pass from one heart muscle cell to another so that they beat simultaneously. Since heart muscle cells specifically make this protein, it suggests that the bone marrow stem cells are becoming heart cells.
Even more remarkably, the transformed bone marrow stem cells showed calcium-handling proteins and calcium currents that occurred as a result of stimulation. Heart muscle cells spontaneously form calcium currents in response to a flood of calcium ions from the neighboring cells. Heart muscle cells have calcium channels called L-type calcium channels. Particular drugs block these channels, and they are sometimes prescribed to lower blood pressure. The inducible calcium channels in the transformed bone marrow stem cells could be inhibited by these calcium channel blocking drugs, which argues that the calcium currents are due to proteins that are usually expressed in heart muscle cells.
These data argue that bone marrow stem cells can become heart muscle cells. Bone marrow treatments have been used in clinical trials for heart attack patients. However, the ability of bone marrow cells to differentiate into heart muscle cells is limited. Even though there is plenty of evidence that bone marrow stem cells can become heart muscle cells, they appear to do so at a very low-frequency. Therefore, changing bone marrow stem cells into heart muscle cells should greatly increase the therapeutic capacity of these cells. Treatment of human bone marrow stem cells with BMP-2 and FGF-2 might transform bone marrow stem cells into heart muscle cells, which would augment the ability of bone marrow stem cells to treat heart attack patients.
A study published in the journal Blood, (Journal of the American Society of Hematology) shows that administration of special chemical called “granulocyte colony-stimulating factor (G-CSF)”, which mobilizes bone marrow stem cells and releases them from the bone marrow into the blood, is unlikely to put healthy stem cell donors at risk for later development of cancer-causing chromosomal abnormalities. The chromosome abnormalities in question involve loss or gains of chromosomes that have been linked to blood-based disorders such as myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML).
When given to stem cell donors, G-CSF moves the donor’s stem cells from the bone marrow into the blood stream. This process is called “mobilization.” Once in the blood, physicians and scientists can collect large doses of stem cells from the peripheral blood safely and without invasive surgery (this process is called “apheresis”). Apheresis avoids bone marrow harvests in the operating room, which can be painful, stressful, and require some recovery time. Research has shown that the large doses of mobilized stem cells, called peripheral blood stem cells or PBSCs, can repopulate the bone marrow and create new blood cells faster than stem cells collected directly from the bone marrow. Furthermore, several long-term follow-up studies have demonstrated that healthy donors are not at an increased risk of developing leukemia or other cancers following PBSC donation.
Betsy Hirsch, first author of the study and Associate Professor in the Department of Laboratory Medicine and Pathology at the University of Minnesota Medical School said: “In recent years, PBSCs have become the dominant source of stem cells for stem cell transplants and the number of transplants performed with PBSCs that have been mobilized with G-CSF has substantially increased. However, the potential for the therapy to cause DNA damage, mutations, or cancer had been suggested in a smaller and less comprehensive prior study, raising a serious concern within the transplant community and making a definitive study very important. Our study aimed at investigating potential effects of G-CSF on chromosomes in healthy donors,”
A research team from the University of Minnesota Medical School conducted a study to determine if G-CSF therapy is indeed a potential cause of chromosome loss or gain in stem cell donors. They asked if there was any risk with short-term, low-dose usage of G-CSF on healthy PBSC donors. Their study evaluated blood samples taken from 22 PBSC donors who had received G-CSF and 22 controls patients who had no history of cancer or prior exposure to G-CSF therapy over a 12 month period.
By using a technique called fluorescence in situ hybridization or FISH, the researchers evaluated the white blood cells of the study subjects for abnormal number of chromosomes. FISH is a sensitive laboratory technique that can detect specific targeted regions of DNA in an individual’s cells to identify chromosomal abnormalities. Loss and gain of chromosomes represent one form of chromosome instability that is frequently a step in the development of cancer. Specifically, the researchers focused on chromosome 7 and a series of other chromosomal regions that are documented to be associated with MDS and AML. The researchers also evaluated the white blood cells from these patients to determine if both copies of each chromosome replicated synchronously or asynchronously. Asynchronous replication can also signal genomic instability and a higher risk of chromosomal abnormalities, and if G-CSF stimulates asynchronous chromosomal replication, if could predispose stem cell donors to higher cancer rates.
The outcomes of this research, however are clear. According to Betty Hirsch: “Contrary to the previously published data, our study concludes that G-CSF stimulation does not result in replication asynchrony or induce the atypical levels of abnormality for chromosome 7 or other chromosomes that have been associated with MDS and AML, and we expect that these results can be generalized to all chromosomes,” said Dr. Hirsch.
Jeffrey McCullough, MD, senior study author and Professor in the Department of Laboratory Medicine and Pathology at the University of Minnesota Medical School, added, “Furthermore, our data support the conclusion that G-CSF does not induce chromosomal instability through the PBSC mobilization process and remains a safe therapy for healthy stem cell donors.”
An interesting paper was published in Asian Cardiovascular and Thoracic Annals: Soma Guhathakurta, Usha R Subramanyan, Ramesh Balasundari, Chandan K Das, Nainar Madhusankar, and Kotturathu Mammen Cherian, Stem Cell Experiments and Initial Clinical Trial of Cellular Cardiomyoplasty Asian Cardiovasc Thorac Ann, Dec 2009; 17: 581 – 586.
In this paper, several Indian scientists used bone marrow cells to test three possibilities: 1) to determine whether transplantation of a sheep’s own bone marrow stem cells into the infarcted myocardium could promote the differentiation of those bone marrow cells into beating heart muscles; 2) demonstrate that bone marrow mesenchymal cells could differentiate into heart muscle cells; 3) conduct a clinical trial with patient’s own bone marrow to determine if it could improve the heart function of patients with severe heart problems.
The first stage used five experimental sheep in which a heart attack had been induced (coronary artery ligation), and two control sheep (they started with nine, but one control animal and one experimental animal died). The control sheep did not show any improvement, but the experimental sheep, which received 100,000 to 1,000,000 bone marrow mononuclear cells (injected into the periphery of the infarcted area), showed improvements in blood circulation throughout the heart. Echocardiography demonstrated marginal improvements in ejection fraction at 3 months post-injection. Staining of the heart tissue from the injection site revealed that some of the heart tissue that should have died was still alive. An even more remarkable finding was that throughout the scar, islands of muscle tissue that could not be differentiated from the
surrounding muscle tissue. Since four of the experimental sheep had been injected with unmarked bone marrow, this large island of heart muscle tissue in the heart scar had a different look from the rest of the surround heart muscle.
One experimental animal, however, had been infected with a virus that causes the bone marrow to glow (Green Fluorescent Protein). When this experimental animal was examined with UV light, the island of heart muscle tissue in the scar glowed, demonstrating that the new heart muscle is from the implanted bone marrow.
In the second stage of their experiment, the researchers tried to grow bone marrow cells in culture and differentiate them into heart muscle cells. The technique they used is apparently undergoing a patent process. Therefore, they did not reveal the technique. Nevertheless, the bone marrow cells formed structures that looked like heart muscle, expressed many heart muscle genes (GATA-4, Nkx 2.5, hANP, MLC-2v and MLC-2a), and in the electron microscope, had a definite heart muscle-like structure, but without the structures that connect heart muscle cells together (intercalated discs).
A marginal improvement in myocardial function was noted at 3 months (mean increase in ejection fraction, 6% ±1%), although it plateaued at 6 months. The trial proved tobe safe because there was no procedure-related mortality. There is growing optimism that stem cell therapy may delay heart transplantation.
Finally, they transplanted bone marrow cells into the hearts of 29 patients who suffered from “dilated cardiomyopathy,” which simply means that they have an enlarged heart, or “endstage ischemic cardiomyopathy,” in which the blood vessels of the heart are so clogged that the patient’s heart cannot receive adequate amounts of oxygen even at rest. Also 11 other patients with similar heart problems were injects with endothelial progenitor cells (EPCs), which are also found in bone marrow, but make blood vessels, and occasionally heart muscle. One particular patient was 5-months old and had a congenital case of cardiomyopathy. In this patients, EPC injections caused a spike in the ejection fraction from 32% to 58%. Other EPC-injected patients produced mixed results,from no improvement to a 7% increase in ejection fraction, with no mortality. The differences in the results is probably due to the fact that they used three different ways to deliver these stem cells; intracoronary delivery, direct injection into the heart muscle, and infusion through the pulmonary arteries. A marginal improvement in heart function was noted at 3 months (mean increase in ejection fraction, 6% ±1%), although it plateaued at 6 months. The trial proved to be safe because there was no procedure-related mortality.
This study is a nice example of the combination of animals, test-tube, and clinical studies. The problem is that the clinical study is too unfocused to properly interpret. It is small, and non-randomized. There is no placebo, and the patients showed a wide variety of chronic heart conditions. The fact that no one became horribly ill because of the procedure is encouraging, but the results are all over the board, as are the patients and their conditions, which makes the clinical trial inconclusive with respect to efficacy. This study definitely justifies a larger, more focused, randomized study. Also, the animal and in vitro portion of the study gives excellent, positive evidence that mesenchymal stem cells from bone marrow can transdifferentiate into heart muscle cells. However, the in vitro work shows that the heart muscle made by the mesenchymal stem cells did not make connexion-43, which is essential for gap junctions and physiological connection between the heart muscle cells. This lack of physiological integration can lead to functional isolation of the new heart muscle tissue, which can generate arrhythmias. Engineering these cells with Connexin-43 would be a good start, which has been shown in skeletal muscle cells to prevent functional isolation and arrythymias (see Tolmachov O, et al. Overexpression of connexin 43 using a retroviral vector improves electrical coupling of skeletal myoblasts with cardiac myocytes in vitro. BMC Cardiovasc Disord. 2006 Jun 6;6:25). The second concern is that these presumptive heart muscle cells were not tested for calcium handling proteins. This is important, since some publications that shown that bone marrow stems cells can form cells that approximate heart muscle cells, but these cells lack the calcium-handling machinery necessary to generate a heart beat (Scherschel JA, Soonpa MH, Srour EF, Field LJ and Rubart M (2008). Adult bone marrow–derived cells do not acquire functional attributes of cardiomyocytes upon transplantation into peri-infarct myocardium. Mol Ther 16: 1129–1137). These scientists should go back to look at this as well.
All in all this is a fascinating study that provides some excellent evidence, but also leaves many hanging questions.
Christopher Centeno, who performs stem cells treatments for patients who are considering knee replacement, has submitted another paper that examines the outcomes of his techniques. His former publication examined 227 patients who were followed for between 3 months and 2-3 years. This paper also utilized data from 50-60 ultra-high field MRIs of the re-implant sites. The results were quite encouraging.
Their new paper has 339 patients followed for up to 3-4 years with 210 MRIs of the places where cells were re-implanted. This paper also includes knee outcome data for the “Regenexx-C” procedure. The data included in this work shows that the Regenexx-C procedure is dramatically safer than the knee replacement surgeries it helped many patients avoid. The paper is still in the galley proof stage, and therefore, it will be a few months before it makes it into press.
Centeno and his colleagues also have other publications on the way. There is a paper that focuses on knee/hip patient outcome, which will be published sometime this year or early next (the paper is winding it’s way through the scientific review process). Stem cell orthopedic treatments come in all sorts of shapes and sizes, but many of them are subjected to peer-review. Make sure the specific therapy you’re being offered has data showing it works.
Artificial organs are made by using artificial scaffolds to which stem cells and other supporting cells are added. However, by making smaller versions of human organs, scientists are making small versions of these organs and then implanting them into mice so that they can test the effects of various drugs on them. Researchers at the Massachusetts Institute of Technology (MIT) have developed artificial humanized mouse livers and implanted them into mice. These manufactured livers responded to drugs in ways that are very similar to the way a human liver does, paving the way for safer and more efficient testing of drugs.
According to Alice Chen and her colleagues, in a paper published in the Proceedings of the National Academy of Sciences (PNAS), her team, led by MIT biomedical engineer Sangeeta Bhatia, engineered an artificial liver by growing a triculture of human liver cells (hepatocytes), mouse fibroblasts, and human liver endothelial cells in a three-dimensional polymeric scaffold in a Petri dish. Because primary hepatocytes do not grow well in culture on their own, the fibroblasts and endothelial cells are necessary to stabilize and help the hepatocytes survive.
After about a week the artificial livers resemble a contact lens in shape and texture. By implanting these small structures into the abdomen of a mouse, the livers will recruit blood vessels and successfully integrate with their host’s circulatory systems. The livers will go on to produce human proteins that circulate throughout the mouse’s blood. Furthermore, these artificial livers continued to function for weeks after implantation.
When the researchers treated the animals with drugs known to be metabolized differently by mice and humans, the mice produced drug breakdown products characteristic of human metabolism. These livers could be useful for studying the immune response to infectious pathogens, such as the hepatitis B and C viruses and malaria, which only infect humans and other primates.
In an interview, Chen said, “We’re stabilizing cells on the bench top first, then putting them into mice, in a way where integration and engraftment occurs nearly 100% of the time.” Chen is a former graduate student in the MIT-Harvard Division of Health Sciences and Technology.
The polymer scaffold protects the artificial liver from the host’s immune system, so the devices are not rejected and can be implanted into any mouse strain, including those whose immune systems work normally.
Dimiter Bissig, professor of molecular and cellular biology at Baylor College of Medicine, recently made a chimeric mouse whose livers are almost 95% human. (see Bissig, K.D., S.F. Wieland, P. Tran, M. Isogawa, T.T. Le, F.V. Chisari, I.M. Verma. 2010. Human liver chimeric mice provide a model for hepatitis B and C virus infection and treatment. J. Clin. Invest. 120:924-93). Bissig said, “I personally admire this marriage between top-notch engineering and biology.”
Previous humanized livers have been made by injecting human liver cells into an immunodeficient mouse with a severely damaged liver. The human cells repopulate and regenerate the injured organ, yielding a chimeric mouse. According to Chen, this technique takes months and can produce results that are unpredictable and difficult to reproduce. “The field hasn’t reached the point where it’s a very robust method,” said Chen.
Chimeric animals, however, can produce many more hepatocytes and much more human liver function than the MIT team’s implantable devices can at this time, Bissig points out. The levels of human albumin in Bissig’s chimeric animals’ serum are measured in the milligram-per-milliliter range, whereas the levels in Chen’s models measure at several orders of magnitude lower. Despite these differences, Bissig believes that one model doesn’t necessarily exclude the other, and that each model is useful for different types of applications. “We’re working on the same problem, but coming at it from different angles,” said Bissig.
In the future, Bissig would like to see artificial livers that can actually replace the function of the endogenous liver, rather than just operating alongside it, as in the new model. He imagines that such a device could temporarily help patients in need of an urgent liver transplant, but in situations where suitable donor organs aren’t immediately available.
Note that no embryonic stem cells were used in this procedure.
Stem cell treatments are haunted by the possibility of tumor formation. While these risks are certainly low when it comes to treatment with somatic stem cells (also known as adult stem cells), the risks are much higher when it comes to embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and fetal stem cells (FSCs). For example, so-called “stem cell tourism” whereby travelers in search of untested and unapproved cures travel to countries where less regulation of the art of medicine allows them to participate in stem cell transplants. China has been one of the most prominent places for stem cell transplants, and FSC transplants for neurological conditions have been the treatment of choice. Unfortunately, the results of these treatments has been disastrous, resulting in meningitis, tumors (Ninette Amariglio, et al. Donor-Derived Brain Tumor Following Neural Stem Cell Transplantation in an Ataxia Telangiectasia Patient. PLoS Medicine 2009;6(2):e1000029), and few real cures (see Olle and Insoo Hyun, Medical Innovation Versus Stem Cell Tourism. Science 2009;324(5935):1664-5). Having said that, while tumor formation for ESCs and iPSCs remains a concern, there have been some advances on this front that might make an important clinical difference in the future.
When ESC or iPSC cultures differentiate, they become a morass of different cell types. Some of the cells remain in the embryonic state, while others become committed to one or another cell type. Differentiation during development sometimes requires cues from other cells that either contact the other cells or provide tissue-specific instructions for cells to become this or that or do this or that. For example, the an organ called the thymus results from outpouchings of the endoderm that lines the lower part of the throat. These outpouchings behave in a manner that depends upon the tissue in which they find themselves and the surrounding cues that they encounter. These types of conditions are excruciatingly difficult to recapitulate in a culture dish, and for that reason, no ESC culture has ever formed thymus in the culture dish, although they will form it when placed inside an animal (A Isotani, et al. Formation of a thymus from rat ES cells in xenogeneic nude mouse/rat chimeras. Genes to Cells 2011;16(4):397-405).
Therefore, when ESC or iPSC cultures are differentiated into a particular cells type, it is exceedingly difficult to isolate cells that are purely one cell type unless there is a specific way to select for just that one cell type. For example, if you want to make neurons from ESCs and transplant them into mice that have a particular neurological problem, you must try to ensure that you inject neurons and not neurons contaminated with cells that are also embryonic in nature, because those embryonic cells will go on to cause a tumor. In some cases the isolation techniques have gratly improved, and tumor formation has been brought to zero. For example, Geron Corporation has a cell line called GRNOPC1, which is an “Oligodendrocytes Progenitor Cell” (OPC) line. This cell line was derived from an embryonic stem cell line called H1, which was originally made by James Thomson in 1998. Hans Keirstead at UC Irvine took this ESC line and differentiated it into OPCs, purified them, and then cultured them. OPCs are able to form the conductive myelin sheath that surrounds the extensions of some neurons in the central nervous system. Keirstead has implanted many rodents with this cell line and he has NEVER observed tumors. See the following papers to document this:
- Keirstead HS, et al. Human embryonic stem cell-derived oligodendrocyte profenitor cell transplants remyelinate and restore locomotion after spinal injury. J Neurosci. 2005;25(19):4694-705.
- Cloutier F, et al. Transplantation of human embryonic stem cell-derived oligodendrocyte progenitors into rat spinal cord injuries does not cause harm. Regenerative Medicine 2006;1(4):469-79.
There are other examples of this as well. For example, Qiuxia Lin and colleagues transplanted three different types of cells into the heart of mice that had experienced heart attacks: ESCs, ESCs that had been converted into heart muscle cells, and heart muscle cells had from ESCs, but had been purified by Percoll density gradient separation. They saw tumors in the mice that had been
implanted with the ESCs and the heart muscle cells made from ESCs. However not a single mouse that was implanted
with the heart muscle cells that were made from ESCs and then purified by Percoll density gradient separation showed any evidence of tumors (See Qiuxia Lin, et al. Tumourigenesis in the infarcted rat heart is eliminated through differentiation and enrichment of the transplanted embryonic stem cells. Eur J Heart Fail. 2010;12(11):1179-85). Therefore, with proper purification of the differentiated cells away from the embryonic cells, the risk of tumor formation decreases greatly.
Having said that there are plenty of concerns about tumorigenicity of ESCs and iPSCs. For example, this paper: Ahmed RP, et al. Cardiac tumorigenic potential of induced pluripotent stem cells in an immunocompetent host with myocardial infarction. Regen Med. 2011;6(2):171-8. In this publication, Ahmed and colleagues used iPSCs to make skeletal muscle stem cells, but they did not try to purify the derivatives in any rigorous manner. In 6 of the 16 mice that received implantations of these cells, tumors formed. Likewise, Eva Hedlund and her colleagues in Rudolf Jaenisch’s lab at the Whitehead Institute used the expression of genes that are found in differentiated midbrain neurons to screen for differentiated iPSCs. Unfortunately, undifferentiated cells still expressed these genes, and when they examined their cultures, they still contained embryonic cells that could cause tumors. In a follow-up paper, Marius Wernig and his colleagues implanted these cells after efficiently differenting them into the brains of rats with Parkinson’s disease. They found integration of the neurons they made and improvement of behavior, but tumors still formed. When they used a surface protein that is only found in embryonic cells (SSEA1) to remove the embryonic cells, the grafts caused no tumors een though they were smaller. See Eva Hedlund, et al. Stem Cells 2007;25:1126-35, and Marius Wernig, et al, PNAS 2008;105:5856-61. There are also several papers of very hopeful therapies that caused tumors in the laboratory animals and had to be sent back to the drawing board.
Tumors are a problem, but there are ways around them. It is incumbent on the researchers to convince us that the cells they have made are safe enough for us to trust that they can be placed in our bodies.
Bone marrow, that squishy material that resides inside your bones, especially your long bones, is a treasure-trove of stem cells. Bone marrow has blood-making stem cells called “hematopoietic stem cells,: or HSCs, and a small subset of HSCs are cells that make blood vessels or “endothelial progenitor cells,” or EPCs. HSCs are used in bone marrow transplants for people who have cancers of the blood system and have had their own bone marrow completely destroyed by ionizing radiation or drugs like busulphan or cyclophosphamide. When the patient receives a bone marrow transplant, the stem cells in the bone marrow proliferate and reconstitute the blood-making and immune capacity of the leukemia or lymphoma patient (See R. Haas, et al. High-dose therapy and autologous peripheral blood stem cell transplantation in patients with multiple myeloma. Recent Results in Cancer Research 2011;183:207-38; and Ronjon Chakraverty and Stephen Mackinnon, Allogeneic Transplantation for Lymphoma. Journal of Clinical Oncology2011;29(14):1855-63). Bone marrow also has a supportive tissue called “stroma.”
Stromal cells do not make blood, but it plays an essential supportive role in blood making. The main component of the stroma are the mesenchymal stem cells,: or MSCs. MSCs can readily differentiate into fat, bone, or muscle,but a wide variety of experiments have shown that MSCs can also become heart muscle, blood vessels, glial cells, neurons, and several other cell types. There are other types of stem cells as well that include marrow-isolated adult multilineage-inducible (MIAMI) stem cells, multipotent adult progenitor cells (MAPCs), very-small embryonic-like (VSEL) stem cells, mesodermal progenitor cells (MPCs), and side population (SP) cells. Given the ability of bone marrow to reconstruct another patient’s bone marrow, could it heal another tissue? This question was given a very strange answer when women who had bone marrow transplants from male donors were found to have heart cells that contained a Y chromosome. Since human females have cells with two X chromosomes, the only source of these cells was the bone marrow transplant (see Arjun Deb, et al. Bone marrow-derived cardiomyocytes are present in adult human heart: A study of gender-mismatched bone marrow transplantation patients. Circulation 2003;107(9):1247-9). This finding suggested that bone marrow could be used to heal the hearts of patients who had suffered a heart attack. Initial experiments in mice were astounding. Not only did the implanted bone marrow cells regenerate over half of the heart, the implanted bone marrow cells expressed a bevy of heart-specific genes and the hearts of the bone marrow recipient mice worked extremely well (Donald Orlic, et al. Transplanted adult bone marrow cells repair myocardial infarcts in mice. Annals of the New York Academy of Sciences2001;938:221-9; discussion 229-3). Unfortunately, no one else could recapitulate Orlic’s remarkable studies, and when bone marrow cells were transplanted into mouse hearts in other labs, they helped heart function, but they did not become anything like heart muscle cells (Leora Balsam, et al. Haematopoietic stem cells adopt mature haematopoietic fates in ischemic myocardium. Nature. 2004;428(6983):668-73). In all cases the transplanted bone marrow cells helped improve the function of the hearts of mice that had recently experienced a heart attack, but there were hanging questions as to how they helped the heart. Despite these uncertainties, several clinical trials examined the ability of a patient’s own bone marrow to heal their damaged heart. These trials took patients who had suffered a heart attack and extracted their own bone marrow and then transplanted into the heart of the heart attack patient. A very noninvasive way to transplant the bone marrow that use catheter technologies that are used to perform angioplasty and apply stents (for an EXCELLENT video on this technology, see this link). The catheter was used to introduce bone marrow stem cells into the heart by means of a catheter. This precluded the need to crack the patient’s chest, and was quite safe, since it has already been used in angioplasty. Earl;y studies of Phase I studies just examined the safety of applying stem cells from bone marrow to the heart. While these early Phase I studies were small and nonrandomized, they universally found that procedure was safe. See the following references:
- Birgit Assmus, et al. Transplantation of progenitor cells and regeneration enhancement in acute myocardial infarction (TOPCARE -AMI). Circulation 2002;106:3009-17. 59 patients were treated with intracoronary bone marrow cells, the percent of the blood in the ventricle that was pumped per heartbeat (ejection fraction or EF; it is a major indicator of how well the heart is performing) increased; the tendency for the heart to enlarge decreased, the size of the heart scar decreased and the amount of blood flowing to the heart increased. One patient died during the course of the experiment, but there were no further cardiovascular events, including ventricular arrhythmias or syncope, occurred during one-year follow-up.
- Bodo E. Strauer, et al. Repair of myocardium by autologous intracoronary mononuclear bone marrow transplantation in humans. Circulation 2002;106:1913-18. Results – Ten patients, were injected with intracoronary bone marrow cells 6-10 days after experiencing a heart attack. All in all, the amount of blood pumped per beat (stroke volume), increased, the myocardial scar shrunk, and blood supply to the rest of the heart increased.
- Francisco Fernández=Avilés, et al. Experimental and clinical capability of human bone marrow cells after myocardial infarction. Circulation Research 2004;95:742-8. 20 recent heart attack patients who had suffered a heart attack ~13 days earlier received intracoronary bone marrow cells and, on the average, the EF increased, the volume that remains in the chambers after pumping (end-systolic volume or ESV) decreased (means the heart is beat more effectively), and the motion of the surfaces of the heart increased as well. There were no major adverse events.
Volker Schächinger, et al. Transplantation of progenitor cells and regeneration enhancement in acute myocardial infarction: Final one-year results of the TOPCARE-AMI Trial. Journal of the American College of Cardiology 2004;44(8): 1690-1699. See the other TOPCARE-AMI summary above.
J. Bartunek, et al. Intracoronary injection of CD133-positive enriched bone marrow progenitor cells promotes cardiac recovery after recent myocardial infarction: feasibility and safety. Circulation. 2005;112(9 Suppl):I178-83. 19 recent heart attack patients received intracoronary bone marrow cells 10-13 days after suffering a heart attack and on the average, patients showed an increase in ejection fraction, increase in circulation throughout the heart and fewer dead cells in the heart. No major adverse effects.
These studies established the safety of the procedure, but these studies were small, and they were no tested against a placebo. Therefore, randomized studies were conducted to test the efficacy of bone marrow transplants in the heart to treat heart attack patients. Remember, drug treatments slow the heart down and delay further cardiac deterioration, but they do not address the problem of dead heart tissue. Only regenerative treatments can potentially replace the dead heat tissue with new, living tissue. Phase II studies and other studies that were combined Phase I/II studies examined just over 900 patients in almost 20 clinical trials and the result overwhelmingly show that bone marrow transplants significantly improve the function of the hearts of heart attack patients. A few studies are negative, that is there are no statistically significant differences between the placebo and the experimental patients. However, the vast majority of the studies are positive, and those studies that are negative seem to have a viable explanation as to why they are so. These studies are listed below:
- Shao-liang Chen, et al. Effect on left ventricular function of intracoronary transplantation of autologous bone marrow mesenchymal stem cell in patients with acute myocardial infarction. American Journal of Cardiology 2004;94(1): 92-95. In this study, 69 patients participated, but only 34 received the intracoronary bone marrow-derived mesenchymal stem cells approximately 18 days after experiencing a heart attack. Patients who had received the stem cells showed a significant increase in ejection fraction versus those patients that had received the placebo. There were no adverse reactions.
- Junbo Ge, et al. Efficacy of emergent transcatheter transplantation of stem cells for treatment of acute myocardial infarction (TCT-Stami). Heart 2006;92(12):1764-7. 20 patients were treated, the moment they received angioplasty less than a day after they has experience a heart attack. 1o received the placebo and 10 received the bone marrow cells. Those who received the bone marrow cells showed enhanced ejection fraction, better heart circulation, and showed no signs of enlargement of the heart relative to the placebo group, which showed a decrease in EF, signs of heart enlargement and decreased heart circulation. There were no adverse reactions.
- Wen Ruan, et al. Assessment of left ventricular segmental function after autologous bone marrow stem cells transplantation in patients with acute myocardial infarction by tissue tracking and strain imaging. Chinese Medical Journal 2005;118(14):1175-81. Less than one day after a heart attack, twenty patients were randomly treated with intracoronary injections of bone-marrow cells (N= 9) or diluted serum (n = 11). Echocardiograms at 1 week, 3 weeks and 3 and 6 months after treatment were used to assess the status of the patient’s hearts, and various means were used to assess left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV). They found that bone marrow stem cells helped improve global and regional contractility and attenuate post-infarction left ventricular remodeling. There were clear increases in EF, and clear decreases in EDV and ESV. There were no adverse reactions.
- Huang RC, et al. Long term follow-up on emergent intracoronary autologous bone marrow mononuclear cell transplantation for acute inferior-wall myocardial infarction. Long term follow-up on emergent intracoronary autologous bone marrow mononuclear cell transplantation for acute inferior-wall myocardial infarction. Zhonghua Yi Xue Za Zhi 2006; 86(16):1107-10. This article is only in Chinese, which I do not read. Therefore this is a summary of the abstract, which is in English. Forty patients who had just experience a heart attack were treated with angioplasty and intracoronary transplantation of autologous bone marrow cells (n = 20) or normal saline and heparin (n = 20) less than one day after the heart attack. After six months, the treated group had higher EFs and greater decrease in the size of the heart scar.
- Kang Yao, et al. Administration of intracoronary bone marrow mononuclear cells on chronic myocardial infarction improves diastolic function. Heart 2008;94:1147-53. 47 patients who had just experienced a heart attack received either intracoronary infusion of bone marrow cells (24 of them), or a saline infusion (23 of them) 5-21 days after experiencing the heart attack. Bone marrow treatments did not lead to significant improvement of cardiac systolic function, infarct size or myocardial perfusion, but did lead to improvement in diastolic function.
- Martin Penicka, et al. Intracoronary injection of autologous bone marrow-derived mononuclear cells in patients with large anterior acute myocardial infarction. Journal of the American College of Cardiology. 2007 49(24):2373-4. This study was a bit of a mess. It was prematurely terminated, and four patients died or had severely worsened heart failure during the study. The authors do not provide details on how they isolated and prepared their bone marrow stem cells, which turns out to be quite important. 27 patients were treated nine days after a heart attack with either intracoronary bone marrow cells (n = 17) or just angioplasty (n = 10). There were no significant differences between the two groups. Given the problems with this paper, the results do not inspire much confidence.
- The BOOST study. Three papers – (1) Arnd Schaefer, et al. Impact of intracoronary bone marrow cell transfer on diastolic function in patients after acute myocardial infarction: results from the BOOST trial. European Heart Journal 2006;27(8):929-35. (2) Kai C. Wollert, et al. Intracoronary autologous bone-marrow cell transfer after myocardial infarction: the BOOST randomised controlled clinical trial. The Lancet 2004;364(9429):141-8. (3) Gerd P. Meyer, et al. Intracoronary Bone Marrow Cell Transfer After Myocardial Infarction: Eighteen Months’ Follow-Up Data From the Randomized, Controlled BOOST (BOne marrOw transfer to enhance ST-elevation infarct regeneration) Trial. Circulation 2006;113:1287-94. This study examined 60 heart attack patients and treated 30 of them with intracoronary bone marrow stem cells and other 30 with just angioplasty 4-8 days after the heart attack. At six-months there was a significant increase in ejection fraction in the bone marrow-recipient group, but those differences between the bone marrow group and the control disappeared after six months and during the 18 month follow-up, no differences could be detected. At the five-year follow-up, no differences could be detected between the two groups. Therefore these authors suggested that early recovery is served by the bone marrow cells, but that these effects are not long-term. See Arnd Scharfer, et al. Long-term effects of intracoronary bone marrow cell transfer on diastolic function in patients after acute myocardial infarction: 5-year results from the randomized-controlled BOOST trial—an echocardiographic study. European Journal of Echocardiology 2010;11(2):165-71. No adverse effects were seen in this study.
- Stefan Janssens, et al. Autologous bone marrow-derived stem-cell transfer in patients with ST-segment elevation myocardial infarction: double-blind, randomised controlled trial. The Lancet 2006;267(9505):113-121. This study treated 67 patients less than one day after experiencing a heart attack, and broke the patients into two groups, half of whom were treated with intracoronary bone marrow stem cells (n = 33), and the other half were treated just with angioplasty (n = 34). While there was no significant increase in ejection fraction in the treated group in comparison to the control group after four months, the bone marrow-treated patients showed increased shrinkage of the heart scar and increased regional heart contraction abilities. A follow-up study published in 2009 confirmed these improvements. See Lieven Herbots, et al. Improved regional function after autologous bone marrow-derived stem cell transfer in patients with acute myocardial infarction: a randomized, double-blind strain rate imaging study. European Heart Journal 2009;30(6):662-70.
- REPAIR-AMI – Several papers: (1) Sandra Erbs, et al. Restoration of Microvascular Function in the Infarct-Related Artery by Intracoronary Transplantation of Bone Marrow Progenitor Cells in Patients With Acute Myocardial Infarction: The Doppler Substudy of the Reinfusion of Enriched Progenitor Cells and Infarct Remodeling in Acute Myocardial Infarction (REPAIR-AMI) Trial. Circulation 2007;116:366-74. (2) Throsten Dill, et al. Intracoronary administration of bone marrow-derived progenitor cells improves left ventricular function in patients at risk for adverse remodeling after acute ST-segment elevation myocardial infarction: Results of the Reinfusion of Enriched Progenitor cells And Infarct Remodeling in Acute Myocardial Infarction study (REPAIR-AMI) cardiac Magnetic Resonance Imaging substudy. American Heart Journal 2009;157(3):541-7. (3) Volker Schächinger, et al. Intracoronary infusion of bone marrow-derived mononuclear cells abrogates adverse left ventricular remodelling post-acute myocardial infarction: insights from the reinfusion of enriched progenitor cells and infarct remodelling in acute myocardial infarction (REPAIR-AMI) trial. European Journal of Heart Failure 2009;11(10):973-9. (4) Birgit Assmus, et al. Clinical outcome 2 years after intracoronary administration of bone marrow-derived progenitor cells in acute myocardial infarction. Circulation Heart Failure 2010;3(1):89-96. This large study used 204 patients and treated 102 of them with bone marrow cells and the others with just angioplasty and the infusion of a placebo 3-7 days after suffering a heart attack. This study definitively showed a significant increase in the ejection fraction in comparison to the placebo group. Likewise, the combined end point death and recurrence of heart attacks and rehospitalization for heart failure was significantly reduced in the bone marrow-treated group. A two-year follow-up also showed that these improvements still presisted after two years. No major adverse side effects were observed.
- Jaroslav Meluzin, et al. Autologous transplantation of mononuclear bone marrow cells in patients with acute myocardial infarction: The effect of the dose of transplanted cells on myocardial function. American Heart Journal 2006;152(5):975(e9-15). Also see Roman Panovsky, et al. Cell Therapy in Patients with Left Ventricular Dysfunction Due to Myocardial Infarction. Echocardiography 2008;25(8): 888–897. This study is one of the few to address the dosage of bone marrow cells. These workers randomized 66 patients, and placed them into three groups: 22 of them received the placebo, 22 received a low dose of bone marrow cells (10,000,000 cells), and 22 received a high dose of bone marrow cells (100,000,000 cells). These treatments were given seven days after experiencing a heart attack. At 3 months after the treatment, the ejection fraction was significantly higher in the patients who had received the high dose of bone marrow cells and not the low dose patients. Again, these treatments were by means of intracoronary delivery, and no major adverse effects were observed.
- The ASTAMI Study – Another fairly large study. (1) Ketil Lunde, et al. Exercise capacity and quality of life after intracoronary injection of autologous mononuclear bone marrow cells in acute myocardial infarction: Results from the Autologous Stem cell Transplantation in Acute Myocardial Infarction (ASTAMI) randomized controlled trial. American Heart Journal 2007;154(4):710.e1-8. (2) Jan Otto Beitnes, et al. Left ventricular systolic and diastolic function improve after acute myocardial infarction treated with acute percutaneous coronary intervention, but are not influenced by intracoronary injection of autologous mononuclear bone marrow cells: a 3 year serial echocardiographic sub-study of the randomized-controlled ASTAMI study. European Journal of Echocardiology 2011;12(2):98-106. (3) Ketil Lunde, et al. Autologous stem cell transplantation in acute myocardial infarction: The ASTAMI randomized controlled trial. Intracoronary transplantation of autologous mononuclear bone marrow cells, study design and safety aspects. Scandinavian Cardiovascular Journal 2005;39(3):150-8. (4) Jan Otto Beitnes, et al. Long-term results after intracoronary injection of autologous mononuclear bone marrow cells in acute myocardial infarction: the ASTAMI randomised, controlled study. Heart 2009;95:1983-9. (5) Einar Hopp, et al. Regional myocardial function after intracoronary bone marrow cell injection in reperfused anterior wall infarction – a cardiovascular magnetic resonance tagging study. Journal of Cardiovascular Magnetic Resonance 2011, 13:22This study examined 100 recent heart attack patients and treated 50 of them with intracoronary bone marrow cells and the remaining patients with just angioplasty, 5-7 days after a heart attack. Measurements of heart function at 3, 6, and 12 months, and 3 years after the procedure found no significant differences between the two groups, with the exception of a slightly increased exercise tolerance in the group that received the bone marrow cells. Both the control and the treated group showed the same low numbers of adverse reactions; none of which could be attributed directly to the treatment protocol. This study was negative and it is often brought up by proponents of embryonic stem cells as an example of the failure of bone marrow cells to heal a heart. However, the protocol that was used by the ASTAMI study to isolate and store the bone marrow cells was different from that used by the successful REPAIR-AMI group. Florian Seeger at the University of Frankfurt evaluated the two protocols and found that the ASTAMI bone marrow isolation protocol produced cells that showed poor viability and poor response to chemical factors that are made in the heart after a heart attack that summons stem cells to it and holds them there )See FH Seeger, et al. Cell isolation procedures matter: a comparison of different isolation protocols of bone marrow mononuclear cells used for cell therapy in patients with acute myocardial infarction. 2007;28(6):766-72). The ASTAMI research group has refused to accept that their bone marrow isolation protocol affected the efficacy of their bone marrow stem cells, but Seeger’s work was corroborated by the work of van Beem (see R.T. van Beem, et al. Recovery and functional activity of mononuclear bone marrow and peripheral blood cells after different cell isolation protocols used in clinical trials for cell therapy after acute myocardial infarction. Eurointervention 2008;4(1):133-8). Therefore, the ASTAMI clinical trial used poor quality bone marrow preparations that were destined to fail, and this clinical trial is no indication of the efficacy or lack of efficacy of bone marrow stem cells to treat failing hearts.
- José Suárez de Lezo, et al. Regenerative Therapy in Patients With a Revascularized Acute Anterior Myocardial Infarction and Depressed Ventricular Function. Revista Espaňola de Cardiologia 2007;60(4):357-65. A small study treated 30 patients with either angioplasty (n = 10), a drug called G-CSF, which tends to bring bone marrow stem cells from the bone marrow and into the circulating blood (n = 10), or intracoronary bone marrow cell treatments (n = 10). The bone marrow=treat group showed a 20% increase in ejection fraction whereas the control and G-CSF-treated group only saw 6% and 4% increases, respectively. Patients received their treatments 5-9 days after their heart attacks.
- The FINCELL Trial – Heikki V. Huikuri, et al. Effects of intracoronary injection of mononuclear bone marrow cells on left ventricular function, arrhythmia risk profile, and restenosis after thrombolytic therapy of acute myocardial infarction. European Heart Journal 2008;29(22):2723-2732. 2-6 days after experiencing a heart attack, 80 patients were randomly assigned to receive intracoronary either bone marrow cells (n = 40) or placebo (n = 40) during angioplasty. After 6 months, the bone marrow-treated group showed clear increases in ejection fraction in comparison to the control group. Also, several safety issues, such as “restenosis” or the narrowing of coronary arteries that surround the heart as a result of bone marrow treatments were addressed by this study, since some researchers suspected that bone marrow treatments increased the risk of restenosis. In this study, no increased incidence of restenosis was observed in the bone marrow-treated group.
- REGENT Study – Michał Tendera, et al. Intracoronary infusion of bone marrow-derived selected CD34+CXCR4+ cells and non-selected mononuclear cells in patients with acute STEMI and reduced left ventricular ejection fraction: results of randomized, multicentre Myocardial Regeneration by Intracoronary Infusion of Selected Population of Stem Cells in Acute Myocardial Infarction (REGENT) Trial. European Heart Journal 2009;30(11):1313-21. This study examined 200 patients who had experienced a heart attack, and seven days after the heart attack, they treated these patients with either unselected bone marrow cells (n = 80), selected bone marrow cells (n = 80), or a placebo (n = 40). This large study did not find statistically significant differences between the three groups, but the control group did not show an increase in the ejection fraction, but the unselected and selected bone marrow-treated patients did. The figure shown below is from the Tendera et al., paper that shows the compiled changes in ejection fraction between the three groups:
As you can see, the control group patients experienced a decrease in their ejection fractions, but the two bone marrow-treated groups experienced an increase, even if it was slight. The figure below shows the data for the sickest patients.
As can be seen, for those patients with the sickest hearts there was a significant difference in the increase in the injection fraction and other heart-associated factors. For this reason, this study does not seem definitive. There were three deaths (one in each group), no strokes, four heart attacks (two in the controls and one in each experimental group), and a low rate of re-narrowing of the heart blood vessels. Since this is from 200 total patients, this is a very low rate of adverse events.
- Jay H. Tendera, et al. Results of a phase 1, randomized, double-blind, placebo-controlled trial of bone marrow mononuclear stem cell administration in patients following ST-elevation myocardial infarction. American Heart Journal 2010;160:428-34. In this study forty patients were treated with either intracoronary bone marrow cells or a placebo. The two groups showed no significant differences in ejection fraction after six months, but the bone marrow-treated group showed no enlargement of the heart in response to the heart attack, whereas the control group did. No adverse heart events occurred.
This summarizes the clinical trials that used bone marrow to treat patients who had experienced recent heart attacks (acute myocardial infarctions). The preponderance of the data clearly shows that this procedure is safe, and effective to treat heart attacks. Secondly, several analyses that take the data from these trials and group them together into one gigantic study (a meta-analysis) have been published, and these studies also show that bone marrow treatments for recent heart attacks are safe and effective. Some of these studies are listed below:
- Meng Jiang, et al. Randomized controlled trials on the therapeutic effects of adult progenitor cells for myocardial infarction: meta-analysis. Expert Opinion on Biological Therapy 2010;10(5):667-80).
- Ahmed Abdel-Latif et al, “Adult Bone Marrow-Derived Cells for Cardiac Repair: A Systematic Review and Meta-Analysis,” Archives of Internal Medicine 167, no.10 (2007): 989–97.
- Mihail Hristov, et al, “Intracoronary Infusion of Autologous Bone Marrow Cells and Left Ventricular Function after Acute Myocardial Infarction: A Meta-Analysis,” Journal of Cellular and Molecular Medicine 10, no.3 (2006): 727–33.
- Sheng Kang, et al, “Effects of Intracoronary Autologous Bone Marrow Cells on Left Ventricular Function in Acute Myocardial Infarction: A Systematic Review and Meta-Analysis for Randomized Controlled Trials,” Coronary Artery Disease 19, no.5 (2008): 327–35.
- Shu-ning Zhang, et al, “Intracoronary Autologous Bone Marrow Stem Cells Transfer for Patients with Acute Myocardial Infarction: A Meta-Analysis of Randomised Controlled Trials,” International Journal of Cardiology 136, no.2 (2009): 178–85.
- Enca Martin-Rendon, et al, “Autologous Bone Marrow Stem Cells to Treat Acute Myocardial Infarction: A Systemic Review,” European Heart Journal 29 (2008): 1807–18.
Many questions remain. For example, what are the best cells to treat heart attack patients? What is the best, and safest way to deliver the cells to the heart? When is the best time to treat the heart attack patient? What is the proper cell dosage? What are the best ways to isolate and store the bone marrow extracts? Which cells in the bone marrow are the best cells for heart treatments. These are all the subjects of further research and more clinical trials are in the works.
A patient who is given the name of JS was treated for a bulging disc with steroid drugs that were injected directly into the spinal cord (epidural). Recently, he had a Regenexx C-disc procedure that took mesenchymal stem cells from his own bone marrow and used them to repair the outer layer of his intervertebral disc so that it would not bulge as badly. The procedure was a rousing success, and MRI images of his back showed that the damaged disc was much less bulged that is used to be. He is presently off pain killers and back to part of his active life style.
The pictures are shown below:
While this procedure does not work all the time, the fact that it does work so well for some people means that it should be a consideration as an alternative for back surgery.