ИСТИНА

Reparative and regenerative processes after tissue damage are strongly dependent on successful restoration of vascular network. Mesenchymal stem/stromal cells (MSC) including ADSC located within the vessel wall and closely interacted with endothelial cells appear to be key regulators of angiogenesis and regeneration in adult tissues. Mechanisms of MSC ability to stimulate blood vessel growth and remodeling are extensively studying during last decades. microRNAs (miRs), small noncoding RNAs that regulate gene expression by binding to target mRNAs reducing their stability and/or inhibiting translation, play an important role in MSC regulation. It was demonstrated that miR-92a expressed in endothelial cells was induced in ischemia and involved in the regulation of angiogenesis and vessel patterning. We studied miR-92a impact in ADSC angiogenic properties regulation. ADSC were isolated from subcutaneous fat tissue of healthy young donors (n=4) and cultured up to 2-3 passages. ADSC phenotype characterized by flow cytometry was CD90+/CD73+/CD105+/CD45-/CD31- for all samples and these cells were capable of adipogenic and osteogenic differentiation. We analyzed miR profile in ADSC using Illumina microarrays and found that miR-92a was one of the highly expressed miRs in all ADSC samples. ADSC transfection by pre-miR-92a or anti-miR-92a led to the coordinated changes of miR-92a well-known target genes expression (integrin alpha 5, ITGA5, and mitogen activated protein kinase, MEK4). ADSC with over-expression of miR-92a completely lost the ability to stimulate capillary-like tube formation by endothelial cells (HUVEC) in vitro compared to ADSC transfected by the control gene. However, transfection of ADSC by anti-miR-92a did not significantly increase their stimulating effect in tube formation assay. As paracrine mechanisms are considered to be the most important for realizing of MSC angiogenic potential, we analyzed gene expression (qRT-PCR) and secretion (Bio-Plex assay and ELISA) of some key angiogenic factors in ADSC. We found that mRNA level of vascular endothelial growth factor (VEGF), angiogenin and leptin was slightly increased in ADSC transfected by anti-miR-92a and this tendency was also observed for VEGF secretion. When miR-92a was over-expressed in ADSC secretion of hepatocyte growth factor (HGF) and angiopoetin-1 by these cells significantly decreased compared to the control cells. We conclude that miR-92a might play an important role in the regulation of ADSC ability to stimulate angiogenesis and key angiogenic factors such as VEGF, HGF and angiopoetin-1 are involved in this process. The underlying mechanisms of miR-92a-mediated direct or indirect effects in ADSC need to be further investigated. Anyway, miR-92a could be considered as a promising target for the modulation of ADSC angiogenic potential.