Vascular wall progenitor cells in health and disease.

The vasculature plays an indispensible role in organ development and maintenance of tissue homeostasis, such that disturbances to it impact greatly on developmental and postnatal health. Although cell turnover in healthy blood vessels is low, it increases considerably under pathological conditions. The principle sources for this phenomenon have long been considered to be the recruitment of cells from the peripheral circulation and the re-entry of mature cells in the vessel wall back into cell cycle. However, recent discoveries have also uncovered the presence of a range of multipotent and lineage-restricted progenitor cells in the mural layers of postnatal blood vessels, possessing high proliferative capacity and potential to generate endothelial, smooth muscle, hematopoietic or mesenchymal cell progeny. In particular, the tunica adventitia has emerged as a progenitor-rich compartment with niche-like characteristics that support and regulate vascular wall progenitor cells. Preliminary data indicate the involvement of some of these vascular wall progenitor cells in vascular disease states, adding weight to the notion that the adventitia is integral to vascular wall pathogenesis, and raising potential implications for clinical therapies. This review discusses the current body of evidence for the existence of vascular wall progenitor cell subpopulations from development to adulthood and addresses the gains made and significant challenges that lie ahead in trying to accurately delineate their identities, origins, regulatory pathways, and relevance to normal vascular structure and function, as well as disease.

Genetically modified human myoblasts with eNOS may improve regenerative ability of myogenic stem cells to infarcted heart.

BACKGROUND: Modern therapies of post infarcted heart failure are focused on perfusion improvement of the injured myocardium. This effect can be achieved by, among other means, implanting stem cells which could be genetically modified with factors inducing the formation of new blood vessels in the post infarction scar area. Combined stem cell and gene therapy seems to be a promising strategy to heal an impaired myocardium. The creation of new blood vessels can be indirectly stimulated via factors inducing vascular endothelial growth factor synthesis, for example endothelial nitric oxide synthase (eNOS). The product of this enzyme, nitric oxide, is a molecule that can influence numerous physiological activities; it can contribute to vasodilation, stimulation of endothelial cell growth, prevention of platelet aggregation and leukocyte adhesion to the endothelium. AIM: To verify the pro-angiogenic and regenerative potential of human primary myoblasts and murine myoblast cell line C2C12 transiently transfected with eNOS gene. METHODS: Stem cells (either human or murine) were maintained in standard in vitro conditions. Next, both types of myoblasts were modified using electroporation and lipofection (human and murine cells), respectively. The efficacy of the transfection method was evaluated using flow cytometry. The concentration of eNOS protein was measured by ELISA immunoassay. The biological properties of modified cells were assessed using an MTT proliferation test and DAPI cell cycle analysis. To verify the influence of oxidative stress on myoblasts, cytometric tests using Annexin V and propidium iodide were applied. To check possible alterations in myogenic gene expression of stem cells transduced by genetic modification, the myogenic regulatory factors were evaluated by real-time PCR. The function of genetic modification was confirmed by a HUVEC capillary sprouting test using myoblasts supernatants. RESULTS: Electroporation turned out to be an efficient transfection method. High amounts of secreted protein were obtained (in the range 2,000 pg/mL) in both cell types studied. Moreover, the functionality of gene overexpression product was confirmed in capillary development assay. Human myoblasts did not exhibit any changes in cell cycle; however, eNOS transfected murine myoblasts revealed a statistically significant reduction in cell cycle ratio compared to controls (p < 0.001). In the case of myogenic gene expression, a decrease in Myogenin level was only detected in the human transfected myoblast population (p < 0.05). CONCLUSIONS: The results of our study may suggest that transplantation of myoblasts overexpressing eNOS could be promising for cell therapy in regenerating the post infarction heart.

[A review on the application of myoblast on gene therapy and tissue engineering].

OBJECTIVE: Because of its special biological characteristics, myoblast might play a role in gene delivery and cell-to-biomaterial interactions. In this paper, the biological features of myoblast and its application on gene therapy and tissue engineering was discussed. METHODS: Documents about proliferation and differentiation of myoblast were reviewed in details. The prospects of its application on gene therapy and tissue engineering were also presented. RESULTS: Myoblast was important in muscle regeneration. The activation of myoblast to proliferate and differentiate was the very beginning of regeneration after injury. The cultured myoblast had high potential to proliferate, it was ready to fuse with each other and to form myotube (the special behavior of myoblast differentiation). Myoblast transplantation had been studied as a possible treatment for inherited myopathies, such as Duchenne muscular dystrophy. The transplanted myoblast could fuse with host myofibers, so the delivered target gene integrated into host. Several myoblast-mediated gene delivery system had been established, including the gene delivery of human factor IX (hFIX), erythropoietin (EPO) and clony stimulating factor-1 (CSF-1). Results from animal experiments demonstrated that myoblast-mediated gene delivery could be used as gene therapy for some inherited diseases. And recently, some authors have shown great interest in the interaction between myoblast and type I collagen gels. It was found that myoblast could keep on proliferating and differentiating in collagen gels and could form discoid, tubular materials. CONCLUSION: Myoblast has great importance in gene therapy and tissue engineering. It is suggested that more efforts should be made in this field.