Myogenic progenitor cell transplantation for muscle regeneration following hindlimb ischemia and reperfusion

Discovery of fibroblast growth factor 2-derived peptides for enhancing mice skeletal muscle satellite cell proliferation

Skeletal muscle satellite cells (SCs) are essential for muscle regeneration. Their proliferation and differentiation are influenced by fibroblast growth factor (FGF)-2. In this study, we screened for FGF-2-derived peptides that promote SC proliferation. Utilizing photocleavable peptide array technology, a library of 7-residue peptides was synthesized, and its effect on SC proliferation was examined using a mixture of five peptides. The results showed that peptides 1-5 (136%), 21-25 (136%), 26-30 (141%), 31-35 (159%), 71-75 (135%), 76-80 (144%), and 126-130 (137%) significantly increased SC proliferation. Further experiments revealed that peptide 33, CKNGGFF, enhanced SC proliferation. Furthermore, its extended form, peptide 33-13, CKNGGFFLRIHPD, promoted SC proliferation and increased the percentage of Pax7-positive cells, indicating that SCs were maintained in an undifferentiated state. The addition of FGF-2 and peptide 33-13 further induced cell proliferation but did not increase the percentage of Pax7-positive cells. A proliferation assay using an FGF receptor (FGFR) inhibitor suggested that peptide 33-13 acts through the FGFR-mediated and other pathways. Although further research is necessary to explore the mechanisms of action of these peptides and their potential for in vivo and in vitro use, the high sequence conservation of peptides 33 and 33-13 in FGF-2 across multiple species suggests their broad application prospects in biomedical engineering and biotechnology.

Differentiation Capacity of Porcine Skeletal Muscle-Derived Stem Cells as Intermediate Species between Mice and Humans

Large animal experiments are important for preclinical studies of regenerative stem cell transplantation therapy. Therefore, we investigated the differentiation capacity of pig skeletal muscle-derived stem cells (Sk-MSCs) as an intermediate model between mice and humans for nerve muscle regenerative therapy. Enzymatically extracted cells were obtained from green-fluorescence transgenic micro-mini pigs (GFP-Tg MMP) and sorted as CD34+/45- (Sk-34) and CD34-/45-/29+ (Sk-DN) fractions. The ability to differentiate into skeletal muscle, peripheral nerve, and vascular cell lineages was examined via in vitro cell culture and in vivo cell transplantation into the damaged tibialis anterior muscle and sciatic nerves of nude mice and rats. Protein and mRNA levels were analyzed using RT-PCR, immunohistochemistry, and immunoelectron microscopy. The myogenic potential, which was tested by Pax7 and MyoD expression and the formation of muscle fibers, was higher in Sk-DN cells than in Sk-34 cells but remained weak in the latter. In contrast, the capacity to differentiate into peripheral nerve and vascular cell lineages was significantly stronger in Sk-34 cells. In particular, Sk-DN cells did not engraft to the damaged nerve, whereas Sk-34 cells showed active engraftment and differentiation into perineurial/endoneurial cells, endothelial cells, and vascular smooth muscle cells, similar to the human case, as previously reported. Therefore, we concluded that Sk-34 and Sk-DN cells in pigs are closer to those in humans than to those in mice.

Skeletal Muscle-Derived Cell Implantation for the Treatment of Fecal Incontinence: A Randomized, Placebo-Controlled Study

BACKGROUND AND AIMS

Fecal incontinence (FI) improvement following injection of autologous skeletal muscle-derived cells has been previously suggested. This study aimed to test the efficacy and safety of said cells through a multicenter, placebo-controlled study, to determine an appropriate cell dose, and to delineate the target patient population that can most benefit from cell therapy.

METHODS

Patients experiencing FI for at least 6 months were randomized to receive a cell-free medium or low or high dose of cells. All patients received pelvic floor electrical stimulation before and after treatment. Incontinence episode frequency (IEF), FI quality of life, FI burden assessed on a visual analog scale, Wexner score, and parameters reflecting anorectal physiological function were all assessed for up to 12 months.

RESULTS

Cell therapy improved IEF, FI quality of life, and FI burden, reaching a preset level of statistical significance in IEF change compared with the control treatment. Post hoc exploratory analyses indicated that patients with limited FI duration and high IEF at baseline are most responsive to cells. Effects prevailed or increased in the high cell count group from 6 to 12 months but plateaued or diminished in the low cell count and control groups. Most physiological parameters remained unaltered. No unexpected adverse events were observed.

CONCLUSIONS

Injection of a high dose of autologous skeletal muscle-derived cells followed by electrical stimulation significantly improved FI, particularly in patients with limited FI duration and high IEF at baseline, and could become a valuable tool for treatment of FI, subject to confirmatory phase 3 trial(s). (ClinicalTrialRegister.eu; EudraCT Number: 2010-021463-32).

Improving the ischemia-reperfusion injury in vascularized composite allotransplantation: Clinical experience and experimental implications

Long-time ischemia worsening transplant outcomes in vascularized composite allotransplantation (VCA) is often neglected. Ischemia-reperfusion injury (IRI) is an inevitable event that follows reperfusion after a period of cold static storage. The pathophysiological mechanism activates local inflammation, which is a barrier to allograft long-term immune tolerance. The previous publications have not clearly described the relationship between the tissue damage and ischemia time, nor the rejection grade. In this review, we found that the rejection episodes and rejection grade are usually related to the ischemia time, both in clinical and experimental aspects. Moreover, we summarized the potential therapeutic measures to mitigate the ischemia-reperfusion injury. Compare to static preservation, machine perfusion is a promising method that can keep VCA tissue viability and extend preservation time, which is especially beneficial for the expansion of the donor pool and better MHC-matching.

Therapeutic potential of mesenchymal stem cells for peripheral artery disease in a rat model of hindlimb ischemia

OBJECTIVES

Mesenchymal stem cells are viewed as the first choice in regenerative medicine. This study aimed to elucidate the influence of BM-MSCs transplantation on angiogenesis in a rat model of unilateral peripheral vascular disease.

MATERIALS AND METHODS

Twenty-one rats were arbitrarily allocated into three groups (7/group). Group I: control sham-operated rats, Group II: control ischemic group: Rats were subjected to unilateral surgical ligation of the femoral artery, and Group III: ischemia group: Rats were induced as in group II, 24 hr after ligation, they were intramuscularly injected with BM-MSCs. After scarification, gastrocnemius muscle gene expression of stromal cell-derived factor-1 (SDF-1), CXC chemokine receptor 4 (CXCR4), vascular endothelial growth factor receptor 2 (VEGFR2), von Willebrand factor (vWF), and hypoxia-inducible factor-1α (HIF-1α) were analyzed by quantitative real-time PCR. Muscle regeneration and angiogenesis evaluation was assessed through H&E staining of the tissue. Furthermore, Pax3 and Pax7 nuclear expression was immunohistochemically assessed.

RESULTS

Rats treated with BM-MSCs showed significantly raised gene expression levels of SDF-1, CXCR4, VEGFR2, and vWF compared with control and ischemia groups. H&E staining of the gastrocnemius showed prominent new vessel formation. Granulation tissue within muscles of the ischemic treated group by BM-MSCs showed cells demonstrating nuclear expression of Pax3 and Pax7.

CONCLUSION

BM-MSCs transplantation has an ameliorating effect on muscle ischemia through promoting angiogenesis, detected by normal muscle architecture restoration and new blood vessel formations observed by H&E, confirmed by increased gene expression levels of SDF-1, CXCR4, VEGFR2, and vWF, decreased HIF-1α gene expression, and increased myogenic Pax7 gene expression.