Yang et al. Clin Toxicol (Phila). 2011 Apr;49(4):298-302.
Paraquat is a herbicide that is linked to development of Parkinsons. It also is a toxin to lung cells and is used as a model of inducing lung injury in rats. In the current study the investigators wanted to see if administration of bone marrow mesenchymal stem cells had a therapeutic effect on paraquat-induced lung injury in rats.
The investigators used 54 female SD rats that were randomly divided into four groups:
a) Paraquat treated group,
b) Paraquat and bone marrow mesenchymal stem cell treated group,
c) Bone marrow mesenchymal stem cell alone treated group
d) Control untreated group
The stem cells were injected intravenously and animals were sacrificed 14 days after injection.
While animals receiving paraquat alone lived an averaty of 9.6 days, all rats receiving bone marrow mesenchymal stem cells lived more than 14 days. Bone marrow mesenchymal stem cell treatment was associated with less wet lung, decreases in plasma IL-1 and TNF-alpha, decrease in MDA, and decrease in NF-kappa B. Upregulated levels of the antioxidant enzyme superoxide dismutase was observed.
The ability to stimulate repair of the lung by mesenchymal stem cells is not new. Previous studies have shown that mesenchymal stem cells are capable of reducing endotoxin induced lung injury by secretion of keratinocyte growth factor. Other studies have shown that mesenchymal stem cells produce interleukin 1 receptor antagonist in the bleomycine induced model of lung fibrosis.
As with other stem cell therapies described on this website, there is some controversy as to the biological mechanisms by which the stem cells are mediating their therapeutic effect. One possibility is that they are secreting growth factors that stimulate proliferation of endogenous stem cells that are already resident in the lung. The other possibility is that the stem cells are directly differentiating into lung tissue.
Bone Marrow Stem Cells Protect Lungs from Herbicide Injury
UW Researchers Make Stem Cell Breakthrough
Seung Park, Badger Herald
Researchers at the University of Wisconsin have made a breakthrough in stem cell research. Igor Slukvin headed the team that has successfully reprogrammed bone marrow cells into induced pluripotent stem cells (iPSCs). “This is important because blood banks have huge amounts of samples of bone marrow,” he said. “You can select as many types of cells as you want and make stem cells out of them.”
This regression was a major accomplishment, as reprogramming a cell is similar to an adult human reversing development and becoming a child again, according to Timothy Kamp, an associate professor of medicine. “When our organs develop, it’s a one-way street as you go from a precursor stem cell which grows and forms specialized tissues for various systems,” Kamp said. “As these cells grow progressively more specialized, they can’t go back and return to being a stem cell.” Obviously, this problem has been overcome, the concept behind the reprogramming comes from a set of DNA binding proteins that regulate gene expression.
Slukvin also took cells from a patient with chronic myeloid leukemia and generated transgene-free iPSCs from their bone marrow. These cells show a unique translocation of a chromosome while also maintaining the pluripotency of an embryonic stem cell. The implication of this being that the disease can now be followed, as they have regressed back into stem cells, the redevelopment of the disease will be able to be observed.
New Stem Cells Found in Ovary
Parte et al. Stem Cells Dev.
Very small embryonic like cells (VSEL) are a type of stem cell that appears to be found in bone marrow and other tissues of the body, presumably as a remnant of embryonic or embryonic-like cells left over from development. In a recent paper it was demonstrated that these cells may be found in the ovary surface epithelium in adult rabbit, sheep, monkey and menopausal human.
Indian scientists found two distinct populations of putative stem cells of variable size were detected in the ovary surface epithelium: one being smaller in size around the range of 1-3 micrometers and the other being of a size approximate to the surrounding erythrocytes.
The smaller cells resembled VSELs and were pluripotent in nature with nuclear Oct-4 and cell surface SSEA-4. The larger cells were 4-7micrometers and possessed cytoplasmic localization of Oct-4 and minimal expression of SSEA-4. The scientists believed that the larger cells were possibly the progenitor germ cells.
The VSEL cells were capable of spontaneously differentiating into oocyte-like structures, parthenote-like structures, embryoid body-like structures, cells with neuronal-like phenotype and embryonic stem (ES) cell-like colonies. They expressed Oct-4, Oct-4A, Nanog, Sox-2, TERT, and Stat-3 as detected by RT-PCR.
Germ cell markers like c-Kit, DAZL, GDF-9, VASA and ZP4 were immuno-localized in oocyte-like structures formed from the VSEL.
These studies are interesting because prior to this there were reports of bone marrow derived cells being implicated in production of oocytes. Specifically, Jonathan Tilley from Harvard reported that bone marrow transplantation can give rise to new oocytes that are donor derived http://www.ncbi.nlm.nih.gov/pubmed/17664466.
If these studies are reproducible it may be that adult stem cells could be useful in the treatment of infertility. Conversely it may be possible to repair oocytes of women who have undergone chemo/radiation therapy. Interestingly, Tilly’s group also published that ovarian tissue contains VSEL-like cells http://www.ncbi.nlm.nih.gov/pubmed/20188358
Limb Transplants Facilitated by Bone Marrow Stem Cells
Kuo et al. Plast Reconstr Surg. 2011 Feb;127(2):569-79.
Composite tissue allografts are usually transplants of anatomical structures that contain multiple types of tissues. We have seen numerous high-profile examples of human composite tissue allografts such as whole hands, faces, and arms. While advancement of surgical techniques have made such transplants a reality, immunologically-mediated rejection remains a formidable problem.
Mesenchymal stem cells are particularly interesting in terms of an “adjuvant” to transplant immune suppression for several reasons.
Firstly, mesenchymal stem cells are known to be immune modulatory. It is known that these cells suppress activation of dendritic cells (which are involved in stimulating immune responses). Mesenchymal stem cells also inhibit CD4 and CD8 T cell responses. This is beneficial in that the CD4 cell coordinates immune attacks and the CD8 T cell causes cytotoxicity of organs that are being rejected. Perhaps even more interestingly, mesenchymal stem cells are known to stimulate production of T regulatory cells. These are cells of the immune system that suppress other immune cells and are associated with prolongation of transplanted graft survival. At a molecular level how the mesenchymal stem cells modulate the immune system seems to involve several biological modulators. Mesenchymal stem cells express the enzyme indomlamine 2,3 deoxygenase, which metabolizes tryptophan. T cells are highly dependent on tryptophan for activation. Mesenchymal stem cells have been demonstrated to actively induce T cell death by localized starvation of tryptophan. Additionally, mesenchymal stem cells produce various immune suppressive cytokines such as Leukemia Inhibitory Factor (LIF), IL-10, TGF-b, and soluble HLA-G. One interesting method by which mesenchymal stem cells suppress the immune system is by expression of surface-bound immune cell killing molecules such as Fas ligand. Evidence supporting the immune suppressive effects of mesenchymal stem cells includes the ability of these cells to control pathological immunity such as graft versus host disease, multiple sclerosis, and Type 1 diabetes.
Secondly, mesenchymal stem cells are known to be angiogenic. This is the process of new blood vessel formation. Subsequent to organ transplantation it is essential that the transplanted organ receive a proper blood supply. While ligation of major blood vessels is performed during the transplantation surgery, proper integration of the donor and recipient blood vessels is an important factor in graft survival.
Thirdly, mesenchymal stem cells have the ability to repair injured organs. There is a substantial amount of injury that occurs as a result of the organ procurement, transportation , and implantation procedure. This injury is termed ischemia/reperfusion injury. The extent of ischemia reperfusion injury contributes more to graft long term survival as compared even to MHC mismatches. As a result of the injury chemoattractants are generated that cause homing of stem cells into the injured organ. It is possible that these stem cells actually contribute to healing and perhaps regeneration of the injured organ.
In the publication discussed, the authors used a porcine model of hind limb transplantation. Four groups of pigs were used:
Group 1: Four untreated recipients
Group 2: Three recipients that received mesenchymal stem cells alone
Group 3: Five recipients that received cyclosporine alone
Group 4: Three recipients that received cyclosporine, irradiation, and mesenchymal stem cells
It was found that treatment with mesenchymal stem cells along with irradiation and cyclosporine A resulted in significant increases in allograft survival as compared with other groups (>120 days; p = 0.018).
Flow cytometric analysis revealed a significant increase in the percentage of CD4/CD25 and CD4/FoxP3 T cells in both the blood and graft in the mesenchymal stem cell/irradiation/cyclosporine A group.
These preliminary data suggest that addition of mesenchymal stem cells to the combination of cyclosporine and irradiation resulted in significant allograft survival. Unfortunately in Group 3 they did not add irradiation so it is impossible to know whether the graft survival was caused by the irradiation or by the mesenchymal stem cells.
Previous collaborations between Thomas Ichim of Medistem and Hao Wang’s group from University of Western Ontario, Canada suggests that a radioresistant element in free bone transplants contributes to prolonged allograft survival. It may be possible that the radioresistant cells were mesenchymal stem cells in nature. This is an area in which future studies are definitely warranted.
New Cell That Keeps Stem Cells in the Bone Marrow
Chow et al. J Exp Med.
When a bone marrow transplant is performed, the bone marrow cells of the donor are injected intravenously into the recipient and somehow find their way back into the bone marrow of the recipient. The mechanism known to be responsible for this has always been cited as being SDF-1 (also called CXCL12) produced by bone marrow “stromal” cells. This mechanism is of fundamental importance to stem cell therapists for two reasons:
Firstly, stem cells are known to be recruited by injured tissue, which produces SDF-1. This has been explained as one of the mechanisms by which both cardiac and brain infarcts cause recruitment of endogenous and exogenous stem cells to the area of injury.
Secondly, by temporarily interrupting the production of SDF-1 or recognition of SDF-1 by CXCR-4, drugs such as Mozibil have been developed which are used in the mobilization of stem cells for patients who mobilize poorly in response to G-CSF.
In a paper that we view as groundbreaking, scientists found that one of the key cells in the bone marrow that produces SDF-1 is the CD169 positive macrophage. The scientists examined three populations of BM mononuclear phagocytes that include Gr-1(hi) monocytes (MOs), Gr-1(lo) MOs, and macrophages (MΦ) based on differential expression of Gr-1, CD115, F4/80, and CD169. Using MO and MΦ conditional depletion models, we found that reductions in BM mononuclear phagocytes led to reduced production of SDF-1 by the bone marrow.
They also found that depletion of CD169(+) MΦ, which spares BM MOs, was sufficient to induce stem cell mobilization. This depletion also enhanced mobilization induced by a CXCR4 antagonist or granulocyte colony-stimulating factor.
Thus it appears that specific macrophage subsets play specific roles in the bone marrow stem cell system. It may be possible to use these macrophages as therapeutic agents to cause recruitment of stem cells into injured organs.
Stem Cells Might Reverse Heart Damage From Chemo
One of the great findings of regenerative medicine was that organs previously believed to be incapable of healing themselves actually contain stem cells that in response to injury cause some degree of healing. The problem being that these "endogenous healing mechanisms" are usually too small to mediate effects that are visible at the clinical level. For example, the brain was considered to have very limited ability to heal itself after damage. Recent studies that have allowed for observation of brain cells after experimental strokes have led to the discovery of brain stem cells in the dendate gyrus and subventricular zones of the brain, stem cells that start to multiple after a stroke. Interestingly, various hormones such as human chonrionic gonadotropin, are capable of stimulating brain stem cell multiplication. This is currently being used in clinical trials for stroke by the company Stem Cell Therapeutics.
In the area of heart failure, it was also believed that once cardiac tissue is damaged, the only repair process that the body performs is production of scar tissue, which is pathological to the patient. While this scar tissue is found in the majority of the injured area, molecular studies have revealed the existence of cardiac specific stem cells, which start to multiply after injury and serve to repair, albeit in small amounts, the infarct area.
One way to augment endogenous repair processes is to administer stem cells from the bone marrow, which are known to produce various growth factors that assist the tissue-specific stem cell in mediating its activity. Another way is to physically extract the tissue specific stem cells, expand them outside of the body and reimplant them into the damaged area.
In a recent publication in the journal Circulation, Piero Anversa, M.D., director, Center for Regenerative Medicine, Departments of Anesthesia and Medicine and Cardiovascular Division, Brigham and Women’s Hospital, Boston and Roberto Bolli, M.D., chief, cardiology, and director, Institute of Molecular Cardiology, University of Louisville, Kentucky, describe the use of cardiac specific stem cells in treatment of animals whose hearts of been damaged by the chemotherapeutic drug doxorubicin.
Doxorubicin is a chemotherapeutic drug that is mainly used in the treatment of breast, ovarian, lung, and thyroid cancers, as well as for neuroblastoma, lymphoma and leukemia. One of the main limiting factors to increasing the dose of doxorubicin to levels that can lead to tumor eradication is that it causes damage to the heart muscle, the myocardium.
In the published study, the investigators expanded the cardiac specific stem cells from rats, gave the rats high doses of doxorubicin and in some rats injected back cardiac specific stem cells, whereas other rats received control cells. The rats that received the cardiac specific stem cells had both preservation of cardiac function, and also regeneration of the damaged heart tissue. This is an important finding since the type of damage that doxorubicin does to the heart is different from other types of heart damage that have been studies, such as the damage that occurs after a heart attack. These data seem to suggest that stem cell therapy may be useful in a variety of injury situations.
"Theoretically, patients could be rescued using their own stem cells," said study author Dr. Piero Anversa, director of the Center for Regenerative Medicine at Brigham and Women’s Hospital in Boston. Dr. Aversa is one of the original discoverers of the cardiac specific stem cell when he published experiments in dogs demonstrating multiplication of cells in the myocardium that seem to have ability to generate new tissue after damage (Linke et al. Stem cells in the dog heart are self-renewing, clonogenic, and multipotent and regenerate infarcted myocardium, improving cardiac function. Proc Natl Acad Sci U S A. 2005 Jun 21;102(25):8966-71).
"A Phase 1 clinical trial using a similar procedure in people is already under way", said Dr. Roberto Bolli, chief of cardiology and director of the Institute of Molecular Cardiology at the University of Louisville in Kentucky, who is heading the trial. The FDA has approved a Phase I clinical trial using cardiac specific stem cells in 30 patients who have congestive heart failure due to disseminated atherosclerosis. "In the trial, participants’ cardiac tissue will be harvested, the stem cells isolated and then expanded in vitro from about 500 cells to 1 million cells over several weeks", Bolli explained. "Several months after the patient has undergone bypass surgery, the stem cells will be re-injected." A similar clinical trial is being performed at Cedars Sinai in Los Angeles.
While the problems of tissue extraction (which is performed by an invasive procedure requiring biopsy of heart tissue) and cost of expansion are still formidable hurdles to widespread implementation, it is believed that the clinical evidence of a therapeutic response will open the door to other avenues of expanding tissue specific stem cells, such as administration of growth factors that can accomplish this without need for cell extraction outside of the body.
Stem Cell as Anti-Aging “Medicine”
Medistem Inc issued a press release describing a collaborative publication between the University of California San Diego, Indiana University, University of Utah, the Dove Clinic for Integrative Medicine, Biotheryx, NovoMedix, The Bio-Communications Research Institute, The Center for Improvement of Human Functioning International and Aidan Products, discussing the contribution of circulating endothelial cells to prevention of aging. The publication also provided data showing that healthy volunteers who have been administered the food supplement Stem-Kine had a doubling of circulating endothelial progenitor cells.
The paper "Circulating endothelial progenitor cells: a new approach to anti-aging medicine?" is freely accessible. "Numerous experiments and clinical trials have been published describing the importance of these repair cells that the body possesses to heal internal organs," stated Dr. Doru Alexandrescu from Georgetown Dermatology, a co-author of the publication. "However, to our knowledge, this is the first comprehensive blueprint in the peer-reviewed literature of how this knowledge may be applied to the question of aging."
The paper summarizes publications describing correlations between decline of circulating endothelial cells and aging/deterioration of several organ systems. The main hypothesis of the publication is that the bone marrow generates a basal number of circulating endothelial cells that serve to continually regenerate the cells that line the blood vessels. Many diseases that are prevalent in aging such as Alzheimer’s are associated with dysfunction of the blood vessel’s ability to respond to various stimuli. This dysfunction is believed to be caused by diminished numbers of circulating endothelial progenitor cells.
Other conditions such as peripheral artery disease are also associated with reduction in this stem cell population, however, when agents are given that increase the numbers of these cells, the degree of atherosclerosis-mediated pathology is decreased. This was demonstrated in a study that administered the drug GM-CSF, which causes an increase in circulating endothelial progenitor cells in a manner similar to Stem-Kine. Unfortunately, drugs currently on the market that have this ability are very expensive and possess the possibility of numerous side effects. The Stem-Kine food supplement is sold as a neutraceutical and is made of natural ingredients that have already been in the food supply.
Another interesting point made by the paper was that the body modulates the number of circulating endothelial progenitor cells based on need. In stroke, the number of circulating endothelial progenitor cells markedly increases in response to the brain damage. Patients in which a higher increase is observed are noted to have a higher chance of recovery. Therapeutic interventions that contain endothelial progenitor cells such as administration of bone marrow cells after a heart attack, are believed to work, at least in part, through providing a cellular basis for creation of new blood vessels, a process called angiogenesis.
Patients with inflammatory conditions ranging from chronic heart failure, to type 2 diabetes, to Crohn’s disease are noted to have a reduction in these cells. The reduction seems to be mediated by the inflammatory signal TNF-alpha. Studies reviewed in the paper describe how administration of antibodies to TNF-alpha in patients with inflammatory conditions results in a restoration of circulating endothelial progenitor cells.
In addition to the possible use of Stem-Kine for restoration/maintenance of circulating endothelial progenitor cells, the publication discusses the possibility of using such cells from sources outside of the body, for example cord blood. Although it was previously thought that cord blood can be used only after strict HLA matching, recent work supports the idea that for regenerative medicine uses, in which prior destruction of the recipient immune system is not required, cord blood may be used without immune suppression or strict tissue matching. This is discussed in the following paper: Cord blood in regenerative medicine: do we need immune
suppression?.
Adenosine inhibits chemotaxis and induces hepatocyte-specific genes in bone marrow mesenchymal stem cells
Bone marrow cells contain several populations that are useful for regenerating injured/aged tissue. These cells include hematopoietic stem cells, mesenchymal stem cells, endothelial progenitor cells, and some argue, progenitor cells left over from embryonic periods that are still capable of differentiating into numerous injured tissue. It has been known for some time that bone marrow cells are capable of treating liver failure both in vitro and in early clinical trials, as can be seen on this video: Stem Cell Therapy for Liver Failure. Other types of stem cells useful for treatment of liver failure, such as cord blood stem cells, may be seen on this video: Cord Blood and Bone Marrow Stem Cells for Liver Failure.
One of the major questions with adult stem cell therapy is how do the stem cells go to where they are needed? Some people have made the argument that stem cells administered intravenously do not cause systemic effect because the majority get stuck in the lung and liver. Although cell sequestration is an issue, numerous studies have demonstrated therapeutic effects after intravenous administration of stem cells. Perhaps the most well-known stem cell homing molecule is stromal derived factor (SDF-1), which is made by injured and/or hypoxic tissue and causes stem cell mobilization and migration through activation of the CXCR4 receptor. The SDF-1/CXCR4 axis has been found in numerous conditions of tissue injury such as: stroke, heart attack, acoustic injured ear, liver failure, and post-transplant reconstitution of bone marrow. To understand how this “chemokine” works, the following video will describe it as relevant to stem cell repopulation post-irradiation: Homing of Stem Cells to Target Tissue
In a study published today scientists examined another signal made by injured tissue in order to assess whether it may act like SDF-1 and “call in” stem cells. The signal chosen was the amino acid adenosine, which is released from injured/necrotic cells. They found that adenosine did not by itself induce chemotaxis of mesenchymal stem cells (MSC) but dramatically inhibited MSC chemotaxis in response to the chemoattractant hepatocyte growth factor (HGF). Inhibition of HGF-induced chemotaxis by adenosine requires the A2a receptor and is mediated via up-regulation of the cyclic adenosine monophosphate (AMP)/protein kinase A pathway. Additionally, the investigators found that adenosine induces the expression of some key endodermal and hepatocyte-specific genes in mouse and human MSCs in vitro.
The ability of adenosine to modulate migration/differentiation processes implies that numerous paracrine/autocrine interactions are occurring during tissue injury. It will be critical to identify how to manipulate such factors to obtain maximal therapeutic responses.
Stem Cell Therapy Aids the Return of Lava Man
Lava Man is a race horse that has had quite a career: he has earned more than $5.2 million and was considered one of the top racehorses in North America. Unfortunately, the recent past has not been to kind to him. Last year he finished last in the 2008 Eddie Read Handicap at Del Mar, and previous to that he has lost a series of six races in a row. Lava Man had arthritis in the joints in his ankles and a small fracture in his left front leg, Being 7 years old at that time, his owners decided it was time for Lava Man to retire.
However it seems like Lava Man’s fortunes may have changed. 17 months after his last race, he is scheduled to make a come-back this Saturday at Hollywood Park in the Native Diver Handicap. The horse was treated with his own fat derived stem cells by Dr. Doug Herthel, who stated:
"The trainer is the only one who can tell you how he’s going to run Saturday, but as far as the way he looks and based on our experience with other horses, theoretically, he should be much better than he was," said Dr. Doug Herthel, who treated Lava Man at the Alamo Pintado Equine Medical Center in Los Olivos, Calif.
"We think of those stem cells as little paramedics," Herthel said. "They go in and they help; they enhance the health of the cartilage." Dr. Herthel stated that significant improvements have occurred in Lava Man following stem cell therapy. He also stated that if Lava Man makes a triumphant return due to stem cells, this would not be the first case of this occurring. He cited the example of Ever A Friend , a 6-year-old horse, who was injured in May 2008, received the same type of fat derived stem cells as Lava Man and returned to win an allowance race and finish second in the Grade I Citation Handicap.
The fat derived stem cells that are being used in the treated of horses appear to work through several mechanisms. On the one hand they can become new cartilage and bone tissue directly, while on the other hand the stem cells producing various growth factors that accelerate the process of healing. Another method, that is more debated amongst scientists, is that the stem cells can actually produce enzymes that degrade scar tissue and allow replacement with functional tissue.
Human use of fat stem cells has been performed for multiple sclerosis (Riordan et al. Non-expanded adipose stromal vascular fraction cell therapy for multiple sclerosis. J Transl Med. 2009 Apr 24;7:29) and is currently being investigated for other conditions such as heart failure and rheumatoid arthritis.
