Acceleration of Skeletal Muscle Regeneration in a Rat Skeletal Muscle Injury Model by Local Injection of Human Peripheral Blood-Derived CD133-Positive Cells

Losartan Improves Adipose Tissue-Derived Stem Cell Niche by Inhibiting Transforming Growth Factor-β and Fibrosis in Skeletal Muscle Injury

Recently, adipose tissue-derived stem cells (ASCs) were emerged as an alternative, abundant, and easily accessible source of stem cell therapy. Previous studies revealed losartan (an angiotensin II type I receptor blocker) treatment promoted the healing of skeletal muscle by attenuation of the TGF-β signaling pathway, which inhibits muscle differentiation. Therefore, we hypothesized that a combined therapy using ASCs and losartan might dramatically improve the muscle remodeling after muscle injury. To determine the combined effect of losartan with ASC transplantation, we created a muscle laceration mouse model. EGFP-labeled ASCs were locally transplanted to the injured gastrocnemius muscle after muscle laceration. The dramatic muscle regeneration and the remarkably inhibited muscular fibrosis were observed by combined treatment. Transplanted ASCs fused with the injured or differentiating myofibers. Myotube formation was also enhanced by ASC+ satellite coculture and losartan treatment. Thus, the present study indicated that ASC transplantation effect for skeletal muscle injury can be dramatically improved by losartan treatment inducing better niche.

The emerging biology of muscle stem cells: implications for cell-based therapies

Cell-based therapies for degenerative diseases of the musculature remain on the verge of feasibility. Myogenic cells are relatively abundant, accessible, and typically harbor significant proliferative potential ex vivo. However, their use for therapeutic intervention is limited due to several critical aspects of their complex biology. Recent insights based on mouse models have advanced our understanding of the molecular mechanisms controlling the function of myogenic progenitors significantly. Moreover, the discovery of atypical myogenic cell types with the ability to cross the blood-muscle barrier has opened exciting new therapeutic avenues. In this paper, we outline the major problems that are currently associated with the manipulation of myogenic cells and discuss promising strategies to overcome these obstacles.

Concise review: Adipose-derived stem cells as a novel tool for future regenerative medicine

The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs offers a paradigm shift that may provide alternative therapeutic solutions for a number of diseases. The use of either embryonic stem cells (ESCs) or induced pluripotent stem cells in clinical situations is limited due to cell regulations and to technical and ethical considerations involved in the genetic manipulation of human ESCs, even though these cells are, theoretically, highly beneficial. Mesenchymal stem cells seem to be an ideal population of stem cells for practical regenerative medicine, because they are not subjected to the same restrictions. In particular, large number of adipose-derived stem cells (ASCs) can be easily harvested from adipose tissue. Furthermore, recent basic research and preclinical studies have revealed that the use of ASCs in regenerative medicine is not limited to mesodermal tissue but extends to both ectodermal and endodermal tissues and organs, although ASCs originate from mesodermal lineages. Based on this background knowledge, the primary purpose of this concise review is to summarize and describe the underlying biology of ASCs and their proliferation and differentiation capacities, together with current preclinical and clinical data from a variety of medical fields regarding the use of ASCs in regenerative medicine. In addition, future directions for ASCs in terms of cell-based therapies and regenerative medicine are discussed.

Induction of muscle regeneration by RNA-mediated mitochondrial restoration

Skeletal muscle injury is associated with general down-regulation of mitochondrial function. Postinjury regeneration of skeletal muscle occurs through activation, proliferation, and differentiation of resident stem cells, including satellite cells and endothelial precursor cells. We wanted to determine the role of mitochondrial function in the regeneration process. Using a previously described method for complex-mediated delivery to intracellular mitochondria, a combination of polycistronic RNAs encoding the H strand of the rat mitochondrial genome was administered to injured rat quadriceps muscle, resulting in restoration of mitochondrial mRNA levels, organellar translation, and respiratory capacity. Intramuscular ATP levels were elevated on pcRNA treatment of injured muscle; concomitantly, levels of reactive oxygen species in the injured muscle were reduced. These effects combined to produce a notable increase in the rate of wound resolution, accompanied by reduction of fibrosis and acceleration of myogenesis, vasculogenesis, and resumption of muscle contractile function. There was evidence of proliferation of Pax7+ satellite cells, expression of muscle-specific regulatory factors in a specific time sequence, and formation of new myofibers in the regenerating muscle. RNA-induced wound resolution and satellite cell proliferation were sensitive to mitochondrial inhibitors, indicating the importance of oxidative phosphorylation. These results highlight the activation of endogenous stem cells through mitochondrial restoration as a possible alternative to implantation of cultured stem cells.

Potential for neural differentiation of mesenchymal stem cells

Adult human stem cells have gained progressive interest as a promising source of autologous cells to be used as therapeutic vehicles. Particularly, mesenchymal stem cells (MSCs) represent a great tool in regenerative medicine because of their ability to differentiate into a variety of specialized cells. Among adult tissues in which MSCs are resident, adipose tissue has shown clear advantages over other sources of MSCs (ease of surgical access, availability, and isolation), making adipose tissue the ideal large-scale source for research on clinical applications. Stem cells derived from the adipose tissue (adipose-derived stem cells = ADSCs) possess a great and unique regenerative potential: they are self-renewing and can differentiate along several mesenchymal tissue lineages (adipocytes, osteoblasts, myocytes, chondrocytes, endothelial cells, and cardiomyocytes), among which neuronal-like cells gained particular interest. In view of the promising clinical applications in tissue regeneration, research has been conducted towards the creation of a successful protocol for achieving cells with a well-defined neural phenotype from adipose tissue. The promising results obtained open new scenarios for innovative approaches for a cell-based treatment of neurological degenerative disorders.

Intramuscular transplantation of muscle-derived stem cells accelerates skeletal muscle healing after contusion injury via enhancement of angiogenesis

BACKGROUND

Muscle contusions are common muscle injuries. Although these injuries are capable of healing, incomplete functional recovery often occurs. Muscle-derived stem cells (MDSCs) are likely derived from blood vessel cells and have a multilineage differentiation potential.

PURPOSE

The aims of this study are (1) to find optimal timing of MDSC transplantation to enhance muscle healing by stimulating muscle regeneration and preventing scar tissue (fibrosis) formation after skeletal muscle contusion injury, and (2) to investigate the role of angiogenesis in the muscle-healing process after MDSC transplantation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Muscle-derived stem cells were injected directly into injured tibialis anterior muscles of mice at various time points (1, 4, and 7 days) after the muscle contusion injury. Muscle regeneration, angiogenesis, and fibrosis formation were evaluated by histology and real-time polymerase chain reaction analysis, and functional recovery was measured by physiologic testing.

RESULTS

Transplantation of MDSCs at 4 days after injury significantly promoted angiogenesis, which was induced by high levels of vascular endothelial growth factor expression at week 1, and significantly increased muscle regeneration and muscle strength by week 2, when compared with the other groups. A decrease in fibrosis formation was observed at week 4, when compared with the other groups, after the transplantation of MDSCs at 4 and 7 days after injury.

CONCLUSION

Intramuscular injection of MDSCs at 4 days after injury improved and accelerated skeletal muscle healing by increasing angiogenesis and decreasing scar tissue formation.

CLINICAL RELEVANCE

These findings could contribute to the development of biologic treatments to aid in muscle healing after muscle injury.

Current advances in cell therapy strategies for muscular dystrophies

INTRODUCTION

Muscular dystrophies are a heterogeneous group of genetic diseases characterized by muscle weakness, wasting and degeneration. Cell therapy consists of delivering myogenic precursor cells to damaged tissue for the complementation of missing proteins and/or the regeneration of new muscle fibres.

AREAS COVERED

We focus on human candidate cells described so far (myoblasts, mesoangioblasts, pericytes, myoendothelial cells, CD133(+) cells, aldehyde-dehydrogenase-positive cells, mesenchymal stem cells, embryonic stem cells, induced pluripotent stem cells), gene-based strategies developed to modify cells prior to injection, animal models (dystrophic and/or immunodeficient) used for pre-clinical studies, and clinical trials that have been performed using cell therapy strategies. The approaches are reviewed in terms of feasibility, hurdles, potential solutions and/or research areas from where the solution may come and potential application in terms of types of dystrophies and targets.

EXPERT OPINION

Cell therapy for muscular dystrophies should be put in the context of which dystrophy or muscle group is targeted, what tools are available at hand, but even more importantly what can cell therapy bring as compared with and/or in combination with other therapeutic strategies. The solution will probably be the right dosage of these combinations adapted to each dystrophy, or even to each type of mutation within a dystrophy.

Acceleration of muscle regeneration by local injection of muscle-specific microRNAs in rat skeletal muscle injury model

MicroRNA (miRNA)s are a class of non-coding RNAs that regulate gene expression post-transcriptionally. Muscle-specific miRNA, miRNA (miR)-1, miR-133 and miR-206 play a crucial role in the regulation of muscle development and homeostasis. Muscle injuries are a common muscloskeletal disorder, and the most effective treatment has not been established yet. The purpose of this study was to demonstrate that a local injection of double-stranded (ds) miR-1, miR-133 and 206 can accelerate muscle regeneration in a rat skeletal muscle injury model. After the laceration of the rat tibialis anterior muscle, ds miR-1, 133 and 206 mixture mediated atelocollagen was injected into the injured site. The control group was injected with control siRNA. At 1 week after injury, an injection of miRNAs could enhance muscle regeneration morphologically and physiologically, and prevent fibrosis effectively compared to the control siRNA. Administration of exogenous miR-1, 133 and 206 can induce expression of myogenic markers, MyoD1, myogenin and Pax7 in mRNA and expression in the protein level at 3 and 7 days after injury. The combination of miR-1, 133 and 206 can promote myotube differentiation, and the expression of MyoD1, myogenin and Pax7 were up-regulated in C2C12 cells in vitro. Local injection of miR-1, 133 and 206 could be a novel therapeutic strategy in the treatment of skeletal muscle injury.

Stem cells to treat muscular dystrophies - where are we?

The muscular dystrophies are inherited disorders characterised by progressive muscle wasting and weakness. Stem cell therapy is considered to be one of the most promising strategies for treating muscular dystrophies. In this review, we first examine the evidence that a stem cell could be used to treat muscular dystrophies, and then discuss the criteria that an ideal stem cell should meet. We also highlight the importance of standard operation procedures to be followed for ensuring the consistent and reproducible efficacy of a particular stem cell. While at the moment the scientific community is looking for an ideal stem cell to treat muscular dystrophies, it is clear that in order for this field to benefit from therapeutic stem cell applications, additional careful investigations are required.

MAPC transplantation confers a more durable benefit than AC133+ cell transplantation in severe hind limb ischemia

There is a need for comparative studies to determine which cell types are better candidates to remedy ischemia. Here, we compared human AC133(+) cells and multipotent adult progenitor cells (hMAPC) in a mouse model reminiscent of critical limb ischemia. hMAPC or hAC133(+) cell transplantation induced a significant improvement in tissue perfusion (measured by microPET) 15 days posttransplantation compared to controls. This improvement persisted for 30 days in hMAPC-treated but not in hAC133(+)-injected animals. While transplantation of hAC133(+) cells promoted capillary growth, hMAPC transplantation also induced collateral expansion, decreased muscle necrosis/fibrosis, and improved muscle regeneration. Incorporation of differentiated hAC133(+) or hMAPC progeny into new vessels was limited; however, a paracrine angio/arteriogenic effect was demonstrated in animals treated with hMAPC. Accordingly, hMAPC-conditioned, but not hAC133(+)-conditioned, media stimulated vascular cell proliferation and prevented myoblast, endothelial, and smooth muscle cell apoptosis in vitro. Our study suggests that although hAC133(+) cell and hMAPC transplantation both contribute to vascular regeneration in ischemic limbs, hMAPC exert a more robust effect through trophic mechanisms, which translated into collateral and muscle fiber regeneration. This, in turn, conferred tissue protection and regeneration with longer term functional improvement.

Expectation of success following noncontingent punishment in introverts and extraverts

Recent findings indicate that extraverts are more likely than introverts to continue responding in the face of punishment and frustrating nonreward (Newman & Kosson, 1984; Tiggemann, Winefield, & Brebner, 1982). The current study investigates whether extraverts' expectations for success are, similarly, resistant to interruption and alteration. To test this hypothesis, 50 introverted and 50 extraverted male undergraduates were exposed to pretreatment with either a 50% level of noncontingent reward or a 50% level of noncontingent punishment. As predicted, there were significant Group X Pretreatment interactions on all dependent measures. In comparison to those introverts who received the punishment pretreatment, extraverts exposed to the same pretreatment placed larger wagers on their ability to succeed, and reported higher levels of perceived control. In addition, relative to their estimates for the pretreatment task, extraverts exposed to noncontingent punishment increased their expectation for success, whereas introverts exposed to noncontingent punishment decreased their performance expectations. No differences were observed between the two groups following pretreatment with noncontingent reward. The results suggest that extraverts are characterized by a distinctive reaction to punishment involving response facilitation as opposed to response inhibition.