Minneapolis Heart Institute Foundation Tests Stem Cell Combination in Heart Attack Patients


The Minneapolis Heart Institute Foundation has announced a new clinical trial that will examine the ability of a stem cell combination to treat patients with ischemic heart failure.

In patients who have suffered from former heart attacks, clogged coronary blood vessels and heart muscle that hibernates can result in a heart that no longer works well enough to support the life of the patient. The lack of blood flow to vital parts of the heart and an increasing work load can result is so-called “Ischemic heart failure.” Such heart failure after a previous heart attack is one of the leading cause of death and morbidity in the world. According to the World Health Organization, ischemic heart disease affects more than 12% of the world’s population.

Stem cell therapy has been tested as a potential treatment for ischemic heart disease. Despite flashes of remarkable success, the overall efficacy of these treatments has been relatively modest. Most clinical trials have used the patient’s own bone marrow cells. In this case, the cell population is very mixed and it might not even be stem cell populations in the bone marrow that are eliciting recovery. Also, the quality of each patient’s bone marrow is probably quite varied, which makes standardizing such experiments remarkably difficult. Other clinical trials have used bone marrow derived mesenchymal cells [MSCs]. Several clinical trials with MSCs have seen some improvement in patients. MSCs seem to induce the formation of new blood vessels and also seem to induce endogenous stem cell populations in the heart to come to life and fix the heart. Other trials have used cardiac stem cells (CSCs) that were derived from biopsies of the heart. Even though fewer clinical trials have tested the efficacy of CSCs in human patients, the trials that have been conducted suggest that these cells can truly regenerate damaged heart tissue.

The Minneapolis Heart Institute Foundation® (MHIF) has announced a new clinical trial which will examine the combination of MSCs with CSCs to treatment patients with ischemic heart failure. This clinical trial, the CONCERT study, will be led by Principal Investigator Jay Traverse, MD. The CONCERT study will implant MSC’s and CSC’s in order to determine if the combination would be more successful than using either alone based on pre-clinical studies in swine demonstrating an enhanced synergistic effect of the combination.

CONCERT is sponsored by the National Institutes of Health and the Cardiovascular Cell Therapy Research Network (CCTRN), of which MHIF is a charter member. This will be a phase II clinical trial, which means that the focus of this leg of the study is to assess the relative safety of CSCs and MSCs, delivered either alone, or in combination, in comparison to placebo, and to measure the efficacy of the stem cell cocktail as well. To that end, researchers will measure and note any change or improvement in left ventricular (LV) function by cardiac MRI as well as changes in various clinical outcomes (survival, 6-minute walking, blood pressure, etc.), and quality of life.

This phase II study is a randomized, blinded, placebo-controlled study that will enroll 160 subjects at seven different CCTRN sites throughout the U.S. All recruited subjects will have ischemic cardiomyopathy and an ejection fraction 5%). This is significant, because some work in animals suggests that CSCs can make new heart muscle tissue that can shrink the heart scar. The first 16 patients were recently enrolled in a FDA-required safety run-in phase, but the remaining patients will be enrolled in the fall after a three-month safety analysis is performed. Incidentally, this is the first cardiac stem cell trial to perform MRIs on patients with defibrillators and pacemakers

“This combination of cells represents the most potent cell therapy product ever delivered to patients,” said Dr. Traverse. “Confirming that both types of stem cells together work better than either individual cell type could lead to improved patient outcomes and better quality of life for ischemic heart failure patients.”

Stem Cell-Based Skin Graft for Severe Burns


Severe wounds are typically treated with full thickness skin grafts. Some new work by researchers from Michigan Tech and the First Affiliated Hospital of Sun Yat Sen University in Guangzhou, China might provide a way to use a patient’s own stem cells to make split thickness skin grafts (STSG). If this technique pans out, it would eliminate the needs for donors and could work well for large or complicated injury sites.

This work made new engineered tissues were able to capitalize on the body’s natural healing power. Dr. Feng Zhao at Michigan Tech and her Chinese colleagues used specially engineered skin that was “prevascularized, which is to say that Zhao and other designed it so that it could grow its own veins, capillaries and lymphatic channels.

This innovation is a very important one because on of the main reasons grafted tissues or implanted fabricated tissues fail to integrate into the recipient’s body is that the grafted tissue lacks proper vascular support. This leads to a condition called graft ischemia. Therefore, getting the skin to form its own vasculature is vital for the success of STSG.

STSG is a rather versatile procedure that can be used under unfavorable conditions, as in the case of patients who have a wound that has been infected, or in cases where the graft site possess less vasculature, where the chances of a full thickness skin graft successfully integrating would be rather low. Unfortunately, STSGs are more fragile than full thickness skin grafts and can contract significantly during the healing process.

In order to solve the problem of graft contraction and poor vascularization, Zhao and others grew sheets of human mesenchymal stem cells (MSCs) and mixed in with those MSCs, human umbilical cord vascular endothelial cells or HUVECs. HUVECs readily form blood vessels when induced, and growing mesenchymal stem cells tend to synthesize the right cocktail of factors to induce HUVECs to form blood vessels. Therefore this type of skin is truly poised to form its own vasculature and is rightly designated as “prevascularized” tissue.

Zhao and others tested their MSC/HUVEC sheets on the tails of mice that had lost some of their skin because of burns. The prevascularized MSC/HUVEC sheets significantly outperformed MSC-only sheets when it came to repairing the skin of these laboratory mice.

When implanted, the MSC/HUVEC sheets produced less contracted and puckered skin, lower amounts of inflammation, a thinner outer skin (epidermal) thickness along with more robust blood microcirculation in the skin tissue. And if that wasn’t enough, the MSC/HUVEC sheets also preserved skin-specific features like hair follicles and oil glands.

The success of the mixed MSC/HUVEC cell sheets was almost certainly due to the elevated levels of growth factors and small, signaling proteins called cytokines in the prevascularized stem cell sheets that stimulated significant healing in surrounding tissue. The greatest challenge regarding this method is that both STSG and the stem cell sheets are fragile and difficult to harvest.

An important next step in this research is to improve the mechanical properties of the cell sheets and devise new techniques to harvest these cells more easily.

According to Dr. Zhao: “The engineered stem cell sheet will overcome the limitation of current treatments for extensive and severe wounds, such as for acute burn injuries, and significantly improve the quality of life for patients suffering from burns.”

This paper can be found here: Lei Chen et al., “Pre-vascularization Enhances Therapeutic Effects of Human Mesenchymal Stem Cell Sheets in Full Thickness Skin Wound Re-pair,” Theranostics, October 2016 DOI: 10.7150/ thno.17031.

Activation of the Proteasome Enhances Stem Cell Function and Lifespan


As we age, the capacity of our stem cells to heal and replace damaged cells and tissues decline. This age-associated decrease in adult stem cell function seems to be a major contributor to the physiological decline during aging. A new paper, by Efstathios Gonos and his colleagues at the National Hellenic Research Foundation in Athens, Greece gives one possible technique that might improve the function of stem cells in an aging body.

Cells contain a multiprotein complex called the “proteasome” that degrades unneeded or defective proteins. The proteasome controls protein half-lives, function, and the protein composition of the cell. Functional failure of the proteasome has been linked to various biological phenomena including senescence and aging. The role of the proteasome in stem cells aging, however has received little attention to date.

Proteasome figure

Gonos and his coworkers used mesenchymal stem cells from umbilical cord Wharton’s Jelly and human fat. Because they were able to compare the proteasome activity in very young and aged stem cells, Gonos and others discovered a significant age-related decline in proteasome content and activity between these two types of stem cells. The proteasome from Warton’s Jelly mesenchymal stem cells were consistently more active and displayed more normal function and activity than those from human fat.  In fact, not only were the protease activities of the proteasomes from the aging stem cells decreased, but they also displayed structural alterations.

These differences in proteasomal activity were not only reproducible, but when the proteasome of young stem cells were compromised, the “stemness,” or capacity of the stem cells to act as undifferentiated cells, was negatively affected.

Even more surprisingly, once after mesenchymal stem cells from human donors lost their ability to proliferate and act as stem cells (their stemness, that is) their decline could be counteracted by artificially activating their proteasomes. Activating the proteasome seems to help the cell “clean house,” get rid of junk proteins, and rejuvenate themselves.

proteasomes-and-stem-cells

Gonos and his team found that the stem cell-specific protein, Oct4, binds to the promoter region of the genes that encode the β2 and β5 proteasome subunits. Oct4 might very well regulate the expression of these proteasome-specific genes.

From this paper, it seems that a better understanding the mechanisms regulating protein turnover in stem cells might bring forth a way to stem cell-based interventions that can improve health during old age and lifespan.

This paper was published in Free Radical Biology and Medicine, Volume 103, February 2017, Pages 226–235.

Positive Results from Mesoblast’s Phase 2 Trial of Cell Therapy in Diabetic Kidney Disease


Mesoblast Limited has announced results from its Phase 2 clinical Trial that evaluated their Mesenchymal Precursor Cell (MPC) product, known as MPC-300-IV, in patients who suffer from diabetic kidney disease. In short, their cell product was shown to be both safe and effective. The results of their trial were published in the peer-reviewed journal EBioMedicine.  Researchers from the University of Melbourne, Epworth Medical Centre and Monash Medical Centre in Australia participated in this study.

The paper describes a randomized, placebo-controlled, and dose-escalation study that administered to patients with type 2 diabetic nephropathy either a single intravenous infusion of MPC-300-IV or a placebo.

All patients suffered from moderate to severe renal impairment (stage 3b-4 chronic kidney disease for those who are interested).  All patients were taking standard pharmacological agents that are typically prescribed to patients with diabetic nephropathy.  Such drugs include angiotensin-converting enzyme inhibitors (e.g., lisinopril, captopril, ramipril, enalapril, fosinopril, ect.) or angiotensin II receptor blockers (e.g., irbesartan, telmisartan, losartan, valsartan, candesartan, etc.).  A total of 30 patients were randomized to receive either a single infusion of 150 million MPCs, or 300 million MPCs, or saline control in addition to maximal therapy.

Since this was a phase 2 clinical trial, the objectives of the study were to evaluate the safety of this treatment and to examine the efficacy of MPC-300-IV treatment on renal function.  For kidney function, a physiological parameter called the “glomerular filtration rate” or GFR is a crucial indicator of kidney health.  The GFR essentially indicates how well the individual functional units within the kidney, known as “nephrons,” are working.  The GFR indicates how well the blood is filtered by the kidneys, which is one way to measure remaining kidney function.  The decline or change in glomerular filtration rate (GFR) is thought to be an adequate indicator of kidney function, according to the 2012 joint workshop held by the United States Food and Drug Administration and the National Kidney Foundation.

nephronanatomy

Diabetic nephropathy is an important disease for global health, since it is the single leading cause of end-stage kidney disease.  Diabetic nephropathy accounts for almost half of all end-stage kidney disease cases in the United States and over 40% of new patients entering dialysis treatment.  For example, there are almost 2 million cases of moderate to severe diabetic nephropathy in 2013.

Diabetic nephropathy can even occur in patients whose diabetes is well controlled – those patients who manage to keep their blood glucose levels at a reasonable level.  In the case of diabetic nephropathy, chronic infiltration of the kidneys by inflammatory monocytes that secrete pro-inflammatory cytokines causes endothelial dysfunction and fibrosis in the kidney.

Staging of chronic kidney disease (CKD) is based on GFR levels.  GFR decline typically defines the progression to kidney failure (for example, stage 5, GFR<15ml/min/1.73m2).  The current standard of care (renin-angiotensin system inhibition with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers) only delays the progression to kidney failure by 16-25%, which leaves a large residual risk for end-stage kidney disease.  For patients with end-stage kidney disease, the only treatment option is renal replacement (dialysis or kidney transplantation), which incurs high medical costs and substantial disruptions to a normal lifestyle.  Due to a severe shortage of kidneys, in 2012 approximately 92,000 persons in the United States died while on the transplant list.  For those on dialysis, the mortality rate is high with an approximately 40% fatality rate within two years.

The main results of this clinical trial were that the safety profile for MPC-300-IV treatment was similar to placebo.  There were no treatment-related adverse events.  Secondly, patients who received a single MPC infusion at either dose had improved renal function compared to placebo, as defined by preservation or improvement in GFR 12 weeks after treatment.  Third, the rate of decline in estimated GFR at 12 weeks was significantly reduced in those patients who received a single dose of 150 million MPCs relative to the placebo group (p=0.05).  Finally, there was a trend toward more pronounced treatment effects relative to placebo in a pre-specified subgroup of patients whose GFRs were lower than 30 ml/min/1.73m2 at baseline (p=0.07).  In other words, the worse the patients were at the start of the trial, the better they responded to the treatment.

The lead author of this publication, Dr David Packham, Associate Professor in the Department of Medicine at the University of Melbourne and Director of the Melbourne Renal Research Group, said: “The efficacy signal observed with respect to preservation or improvement in GFR is exciting, especially given that this trial was not powered to show statistical significance. Patients receiving a single infusion of MPC-300-IV showed no evidence of developing an immune response to the administered cells, suggesting that repeat administration is feasible and may in the longer term be able to halt or even reverse progressive chronic kidney disease. I hope that this very promising investigational therapy will be advanced to rigorous Phase 3 clinical trials to test this hypothesis as soon as possible.”

Patients who received s single IV infusion of MPC-300-IV cells showed no evidence of developing an immune response to the administered cells.  This suggests that repeated administration of MPCs is feasible and might even have the ability to halt, or even reverse progressive chronic kidney disease.

Packham and his colleagues hope that this cell-based therapy can be advanced to a rigorous Phase 3 clinical trial to further test this treatment.

Bone Marrow Mesenchymal Stem Cells Spontaneously Make Cartilage After Blockage of VEGF Signaling


Bone marrow-derived mesenchymal stem cells (MSCs) can be induced to make cartilage by incubating the cells with particular growth factors.  Unfortunately, batches of MSCs show respectable variability from patient-to-patient.  Therefore the growth factor-dependent method suffers from poor efficacy, limited reproducibility from batch-to-batch, and the cell types that are induced are not always terribly stable.  Finding a better way to make cartilage would certainly be a welcome addition to regenerative treatments,

Cartilage that coats the ends of bones is known as articulate cartilage, and articular cartilage lacks blood vessels.  Therefore, is it possible that inhibiting blood vessel formation could conveniently push MSCs to differentiate into cartilage-making chondrocytes?

A new paper by Ivan Martin and Andrea Basil from the University Hospital Basel and their colleagues have used this very strategy to induce cartilage formation in MSCs from bone marrow.

Martin and others isolated MSCs from bone marrow aspirates from human donors.  These cultured human MSCs were then genetically engineered with modified viruses to express a receptor for soluble vascular endothelial growth factor (VEGF) that binds this growth factor, but fails to induce any intracellular signals.  Such a receptor that binds the growth factor but does not induce any biological effects is called a “decoy receptor,” and decoy receptors efficiently sequester or vacuum up all the endogenous VEGF.  VEGF is the major blood vessel-inducing growth factor and it is heavily expressed during development, by cancer cells, and during healing.

After expressing the decoy VEGF receptor in these human MSCs, these genetically engineered cells were grown on collagen sponges and then implanted in immunodeficient mice.  If the implanted MSCs were not genetically engineered to express decoy VEGF receptors, they induced for formation of vascularized fibrous tissue.  However, the implantation of genetically engineered MSCs that expressed the decoy VEGF receptor efficiently and reproducibly differentiated into chondrocytes and formed hyaline cartilage. This is significant because headline cartilage is the very type of cartilage found at articular surfaces where the ends of bones come together to form joints.

In vivo chondrogenesis. Histological staining with Safranin-O for glycosaminoglycans and immunohistochemistry for type II collagen of engineered tissue generated by naïve (control) or sFlk-1 MSCs after 4 (A) or 12 (B) weeks in vivo. Fluorescence staining with DAPI (in blue) and a specific anti-human nuclei antibody (in red) of constructs generated by control or sFlk-1 MSCs after 4 (A) or 12 (B) weeks in vivo. Scale bar = 100 µm. Abbreviations: DAPI, 4′,6-diamidino-2-phenylindole; MSC, bone marrow-derived mesenchymal stromal/stem cell.
In vivo chondrogenesis. Histological staining with Safranin-O for glycosaminoglycans and immunohistochemistry for type II collagen of engineered tissue generated by naïve (control) or sFlk-1 MSCs after 4 (A) or 12 (B) weeks in vivo. Fluorescence staining with DAPI (in blue) and a specific anti-human nuclei antibody (in red) of constructs generated by control or sFlk-1 MSCs after 4 (A) or 12 (B) weeks in vivo. Scale bar = 100 µm. Abbreviations: DAPI, 4′,6-diamidino-2-phenylindole; MSC, bone marrow-derived mesenchymal stromal/stem cell.

This articular cartilage was quite stable and showed no signs of undergoing the chondrocytes enlargement found in terminally differentiated cartilage that is ready to form bone.  This stability was maintained for up to 12 weeks.

In vivo cartilage stability. Immunohistochemistry for type X collagen, BSP, and MMP-13 on sections of hypertrophic cartilage generated in vitro by MSCs (as a positive control) and on sections of the cartilaginous constructs generated in vivo by sFlk1 MSCs 12 weeks after implantation. Scale bar = 50 µm. Abbreviations: BSP, bone sialoprotein; MMP-13, metalloproteinase-13; MSC, bone marrow-derived mesenchymal stromal/stem cell.
In vivo cartilage stability. Immunohistochemistry for type X collagen, BSP, and MMP-13 on sections of hypertrophic cartilage generated in vitro by MSCs (as a positive control) and on sections of the cartilaginous constructs generated in vivo by sFlk1 MSCs 12 weeks after implantation. Scale bar = 50 µm. Abbreviations: BSP, bone sialoprotein; MMP-13, metalloproteinase-13; MSC, bone marrow-derived mesenchymal stromal/stem cell.

Why did inhibition of VEGF signaling induce cartilage?  Inhibition of angiogenesis induced low oxygen tensions, which activated a growth factor called transforming growth factor-β.  Activation of the TGF-beta pathway robustly enhanced the formation of articular cartilage.

In vitro chondrogenesis at different oxygen tensions. Histological staining with Safranin-O and immunohistochemistry for type II collagen on constructs generated in vitro by naïve MSC cultured with (A) or without (B) TGFβ3 supplementation at 2% or 20% of oxygen tension. Scale bar = 50 µm. Expression levels of the mRNA for type II and X collagen, Gremlin-1, IHH TGFβ1 were quantified in pellets generated by naïve bone marrow-derived mesenchymal stromal/stem cells (C, D) cultured in the two different oxygen tensions. ∆Ct values were normalized to expression of the GAPDH housekeeping gene, and results are shown as mean ± SD (n = 6 samples/group from 3 independent experiments). ∗, p < .05, ∗∗∗, p < .001. Abbreviations: GAPDH, glyceraldehyde-3-phosphate dehydrogenase; IHH, Indian hedgehog; TGFβ, transforming grown factor-β.
In vitro chondrogenesis at different oxygen tensions. Histological staining with Safranin-O and immunohistochemistry for type II collagen on constructs generated in vitro by naïve MSC cultured with (A) or without (B) TGFβ3 supplementation at 2% or 20% of oxygen tension. Scale bar = 50 µm. Expression levels of the mRNA for type II and X collagen, Gremlin-1, IHH TGFβ1 were quantified in pellets generated by naïve bone marrow-derived mesenchymal stromal/stem cells (C, D) cultured in the two different oxygen tensions. ∆Ct values were normalized to expression of the GAPDH housekeeping gene, and results are shown as mean ± SD (n = 6 samples/group from 3 independent experiments). ∗, p < .05, ∗∗∗, p < .001. Abbreviations: GAPDH, glyceraldehyde-3-phosphate dehydrogenase; IHH, Indian hedgehog; TGFβ, transforming grown factor-β.

Cartilage formation from MSCs was induced by blocking VEGF-mediated angiogenesis.  These results represent a remarkable advance in cartilage formation that can be used for regenerative treatments.  This cartilage formation was spontaneous and efficient and if it can be carried out with VEGF-inhibiting drugs rather than genetic engineering techniques, then we might have a transferable technique for making cartilage in the laboratory to treat osteoarthritis and other joint-based maladies.  Clinical trials will be required, but this is certainly an auspicious start.

Fat-derived cells Enhance the Bone-Forming Capacity of Hypertrophic Cartilage Matrices


Treating particular bone defects or injuries present a substantial challenges for clinicians. The method of choice usually involves the use of an “autologous” bone graft (“autologous” simply means that the graft comes from the patient’s own bone). However, autologous bone grafts have plenty of limitations. For example, if a patient has a large enough bone defect, there is no way the orthopedist and take bone from a donor site without causing a good deal of risk to the donor site. Even with small bone grafts, so-called “donor site morbidity” remains a risk. Having said that, plenty of patients have had autologous bone grafts that have worked well, but larger bone injuries or defects are not treatable with autologous bone grafts.

The answer: bone substitute materials. Bone substitute materials include tricalcium phosphate, hydroxyapatite, cement, ceramics, bioglass, hydrogels, polylactides, PMMA or poly(methy methacrylate) and other acrylates,, and a cadre of commercially available granules, blocks, pastes, cements, and membranes. Some of these materials are experimental, but others do work, even if do not work every time. The main problem with bone substitute materials is that, well, they are not bone, and, therefore lack the intrinsic ability to induce the growth of new bone (so-called osteoinductive potential) and their ability to integrate into new bone is also a problem at times.

We must admit that a good deal of progress has been made in this area and it’s a good thing too. Many of our fabulous men and women-at-arms have returned home with severe injuries from explosives and wounds from large-caliber weapons that have shattered their bones. These courageous men and women have been the recipient of these technologies. However, the clinician is sometimes left asking herself, “can we do better?”

A new paper from the laboratories of Ivan Martin and Claude Jaquiery from the University Hospital of Basel suggests that we can. This paper appeared in Stem Cells Translational Medicine and describes the use of a hypertrophic cartilage matrix that was seeded with cells derived from the stromal vascular faction of fat to not only make bone in the laboratory, but to also heal skull defects in laboratory animals. While this work benefitted laboratory animals, it was performed with human cells and materials, which suggests that this technique, if it can be efficiently and cheaply scaled up, might be usable in human patients.
The two lead authors of this paper, Atanas Todorov and Matthias Kreutz and their colleagues made hypertrophic cartilage matrices from human bone marrow mesenchymal stem cells (from human donors) that were induced to make cartilage. Fortunately, protocols have been very well worked out and making cartilage plugs with chondrocytes that are enlarged (hypertrophic) is something that has been successfully done in many laboratories. After growing the mesenchymal stem cells in culture, half a million cells were induced to form cartilage with dexamethasone, ascorbic acid 2-phosphate, and the growth factor TGF-beta1. After three weeks, the cartilage plugs were subjected to hypertrophic medium, which causes the cartilage cells to enlarge.

Chondrocyte enlargement is a prolegomena to the formation of bone and during development, many of our long bones (femur, humerus, fibula, radius, etc.), initially form as cartilage exemplars that are replaced by bone as the chondrocytes enlarge. Ossification begins when a hollow cylinder forms in the center of the bone (known as the periosteal collar). The underlying chondrocytes degenerate and die, thus releasing the matrix upon which calcium phosphate crystals accrete. The primary ossification center commences with the calcification of the central shaft of the bone and erosion of the matrix by the invasion of a blood vessel. The blood vessels bring osteoprogenitor cells that differentiate into osteoblasts and begin to deposit the bone matrix.

Next, Todorov and his crew isolated the stromal vascular fraction from fat that was donated by 12 volunteers who had fat taken from them by means of liposuction. The fat is then minced, digested with enzymes, centrifuged, filtered and then counted. This remaining fraction is called the stromal vascular fraction or SVF, and it consists of a pastiche of blood vessel-forming cells, mesenchymal stem cells, and bone-forming cells (and probably a few other cells types too). These SVF cells were seeded onto the hypertrophic cartilage plugs and used for the experiments in this paper.

First, the SVF-seeded plugs were used to grow bone in laboratory rodents. The cartilage plugs were implanted into the backs for nude mice. Different cartilage plugs were used that had been seeded with gradually increasing number of SVF cells. The implanted plugs definitely made ectopic bone, but the amount of bone they made was directly proportional to the number of SVF cells with which they had been seeded. Staining experimental also showed that some of the newly-grown bone came from the implanted SVF cells.

Ectopic bone formation. Grafts based on devitalized hypertrophic cartilage pellets were embedded in fibrin gel without or with stromal vascular fraction cells from adipose tissue and implanted subcutaneously in nude mice. (A): Representative hematoxylin and eosin, Masson-Tri-Chrome, and Safranin-O (Saf-O) staining and in situ hybridization for human ALU sequences (dark blue = positive) after 12 weeks in vivo. Saf-O stainings are blue-green because of lack of glycosaminoglycans and counterstaining with fast green. Osteoid matrix and bone marrow are visible. Scale bars = 200 µm. (B): Stainings for metalloproteinase (MMP)13 and MMP9, as well as for the N-terminal neoepitope at the major MMP cleavage site (DIPEN) after 12 weeks in vivo (red/pink = positive). Scale bars = 50 µm. +, osteoid matrix; ⋆, bone marrow. Abbreviations: ALU, Arthrobacter luteus; H&E, hematoxylin and eosin; Masson, Masson’s trichrome; MMP, metalloproteinase; Saf-O, Safranin-O; SVF, stromal vascular fraction.
Ectopic bone formation. Grafts based on devitalized hypertrophic cartilage pellets were embedded in fibrin gel without or with stromal vascular fraction cells from adipose tissue and implanted subcutaneously in nude mice. (A): Representative hematoxylin and eosin, Masson-Tri-Chrome, and Safranin-O (Saf-O) staining and in situ hybridization for human ALU sequences (dark blue = positive) after 12 weeks in vivo. Saf-O stainings are blue-green because of lack of glycosaminoglycans and counterstaining with fast green. Osteoid matrix and bone marrow are visible. Scale bars = 200 µm. (B): Stainings for metalloproteinase (MMP)13 and MMP9, as well as for the N-terminal neoepitope at the major MMP cleavage site (DIPEN) after 12 weeks in vivo (red/pink = positive). Scale bars = 50 µm. +, osteoid matrix; ⋆, bone marrow. Abbreviations: ALU, Arthrobacter luteus; H&E, hematoxylin and eosin; Masson, Masson’s trichrome; MMP, metalloproteinase; Saf-O, Safranin-O; SVF, stromal vascular fraction.

In the second experiment, Todorov and Kreutz used these SVF-seeded cartilage plugs to repair skull lesions in rats. Once again, the quantity of bone produced was directly proportional to the number of SVFs seeded into the cartilage matrices prior to implantation. In both experiments, the density of SVF cells positively correlates with the bone-forming cells in the grafts and the percentage of SVF-derived blood vessel-forming cells correlates with the amount of deposited mineralized matrix.

Bone repair capacity. Devitalized hypertrophic cartilage pellets were embedded in fibrin gel without or with stromal vascular fraction (SVF) cells from adipose tissue and implanted in rat calvarial defects. (A): Mineralized volume quantified by microtomography (n = 9 grafts assessed per group). (B): Bone area assessed in histological sections, expressed as percentage of total defect area (n = at least 24 sections assessed per group). ∗∗∗∗, p < .0001. (C, D): Representative three-dimensional microtomography reconstructions (left) and hematoxylin/eosin (H&E) staining (right) of the calvarial defects filled with devitalized grafts, implanted without (C) or with (D) activation by SVF cells after 4 weeks. Dotted circles indicate the defect borders (4 mm diameter). Scale bars = 500 µm. (E): Microtomography (left) and H&E staining (middle and right) displaying the bridging between hypertrophic matrix and bone of the calvarium, or the fusion of single pellets (right) in activated grafts. White bar = 850 µm; black bars = 500 µm. Dotted lines indicate the edge of the calvarium. (F): In situ hybridization for Arthrobacter luteus sequences showing the presence of human cells (dark blue, positive) in the explants. Scale bar = 200 µm. Abbreviations: C, calvarium; dev, fibrin gel without stromal vascular fraction; dev + SVF, fibrin gel with stromal vascular fraction; P, hypertrophic matrix; SVF, stromal vascular fraction.
Bone repair capacity. Devitalized hypertrophic cartilage pellets were embedded in fibrin gel without or with stromal vascular fraction (SVF) cells from adipose tissue and implanted in rat calvarial defects. (A): Mineralized volume quantified by microtomography (n = 9 grafts assessed per group). (B): Bone area assessed in histological sections, expressed as percentage of total defect area (n = at least 24 sections assessed per group). ∗∗∗∗, p < .0001. (C, D): Representative three-dimensional microtomography reconstructions (left) and hematoxylin/eosin (H&E) staining (right) of the calvarial defects filled with devitalized grafts, implanted without (C) or with (D) activation by SVF cells after 4 weeks. Dotted circles indicate the defect borders (4 mm diameter). Scale bars = 500 µm. (E): Microtomography (left) and H&E staining (middle and right) displaying the bridging between hypertrophic matrix and bone of the calvarium, or the fusion of single pellets (right) in activated grafts. White bar = 850 µm; black bars = 500 µm. Dotted lines indicate the edge of the calvarium. (F): In situ hybridization for Arthrobacter luteus sequences showing the presence of human cells (dark blue, positive) in the explants. Scale bar = 200 µm. Abbreviations: C, calvarium; dev, fibrin gel without stromal vascular fraction; dev + SVF, fibrin gel with stromal vascular fraction; P, hypertrophic matrix; SVF, stromal vascular fraction.

This is not the first time scientists have proposed the use of cartilage plugs to induce the formation of new bone. Van der Stok and others and Bahney and colleagues were able to repair segmental bone defects in laboratory rodents. Is this technique transferable to human patients? Possibly. Hypertrophic cartilage is relatively easy to make and it is completely conceivable that hypertrophic cartilage wedges can be sold as “off-the-shelf” products for bone treatments. SVF can also be derived from the patient or can be derived from donors.

Furthermore, the protocols in this paper all used human cells and grew the products in immunodeficient rats and mice. Therefore, in addition to scaling this process up, we have a potentially useful protocol that might very well be adaptable to the clinic.

The efficacy of this technique must be confirmed in larger animal model system before human trials can be considered. Hopefully human trials are in the future for this fascinating technique.

Fat-Based Stem Cell Treatment Suggests a New Way to Slow Scarring in Scleroderma Patients


Scleroderma is an autoimmune disease that causes chronic scarring of the skin and internal organs. The deposition of massive quantities of collagen decrease the pliability and elasticity of the skin, lungs, and blood vessels. As you might guess, the prognosis of scleroderma patients is quite poor and this disease causes a good deal of suffering and morbidity.

Treatments options usually include steroids, and other drugs that suppress the immune system, all of which have severe side effects.

New research from scientists at the Hospital for Special Surgery in New York City and other collaborating institutions, led by Dr. Teresa T. Lu, may have identified a new mechanism in operation during the onset and maintenance of scleroderma. This work was published in the Journal of Clinical Investigation.

In this study, scleroderma patients were shown to possess diminished numbers of “adipose-derived stromal cells” (ADSCs) in the layer of fat that underlies the upper layers of the skin. These fatty tissues are referred to as “dermal white adipose tissue.” The loss of these dermal white adipose tissue ADSCs tightly correlates with the onset of scarring in two different mouse model systems that recapitulate scleroderma in laboratory mice. These observations may show that ADSC loss contributes to scarring of the skin.

Why do these ADSCs die? Lu and her coworkers discovered that ADSC survival depends on the presence of particular molecules secreted by immune cells called “dendritic cells.” Skin-based dendritic cells secrete a molecule called lymphotoxin B. Although this molecule is called a toxin, it is required for ADSC survival. In laboratory mice that suffered from a scleroderma-like disease, artificial stimulation of the lymphotoxin B receptor in ADSCs amplified and eventually restored the numbers of ADSCs in the skin. Could stimulating ADSCs in this manner help treat scleroderma patients?

According the Dr. Lu, the administrating author of this publication, injecting “ADSCs is being tried in scleroderma; the possibility of stimulating the lymphotoxin B pathway to increase the survival of these stem cells is very exciting.” Dr. Lu continued, “By uncovering these mechanisms and targeting them with treatments, perhaps one day we can better treat the disease.”

Lu also thinks that a similar strategy that targets stem cells from other tissues might provide a treatment for other rheumatological conditions – such as systemic lupus erythematosis and rheumatoid arthritis. Additionally, bone and cartilage repair might also benefit from such a treatment strategy.

In the coming years, Dr. Lu and her colleagues hope to test the applicability of this work in human cells. If such a strategy works in human cells, then the next stop would be trial in human scleroderma patients. The success of such a treatment strategy would be a welcome addition to the treatment options for scleroderma patients, but only if this treatment is shown to be proven safe and effective.

“Improving ADSC therapy would be a major benefit to the field of rheumatology and to patients suffering from scleroderma,” said Lu.