ИСТИНА

Mesenchymal stem/stromal cells (MSCs) including those from adipose tissue (ADSC) stimulate angiogenesis and regenerative processes in adult tissues. MicroRNAs (miRs), small noncoding RNAs that regulate gene expression by binding to target mRNAs, reducing their stability and/or inhibiting translation, appeared to be important regulators of blood vessel growth. Several miRs, which defined as angio-miRs, were found to be involved in the regulation of angiogenesis and vessel patterning. In this study, we examined the impact of angio-miRs on ADSC angiogenic properties. ADSCs from subcutaneous fat tissue of healthy young donors (n=4) were 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. miR profile in ADSC was analyzed using Illumina microarrays. We found that miR-92a was one of the most abundant angio-miRs (of 17-92 cluster) in all ADSC samples. We transfected ADSC by pre-miR-92a or anti-miR-92a and tested the ability of conditioned medium of transfected cells to stimulate tube formation by HUVECs. ADSC over-expressing miR-92a completely lost the ability to stimulate tubes formation by endothelial cells compared to ADSC transfected by the scramble oligos. However, knockingout miR-92a by transfection with anti-miR-92a did not increase the ability of ADSC to stimulate tube formation. The expression and secretion of angiogenic factors were analyzed by qRT-PCR and Bio-Plex assay. ADSC transfection by pre-miR-92a or anti-miR-92a led to the coordinated changes of mRNAs level of known miR-92a targets, ITGA5 and MEK4, whereas mRNAs of VEGF, angiogenin and leptin were largely unaffected. Consistently with the observed effect of ADSC conditioned medium on tube formation, the secretion of hepatocyte growth factor (HGF) and angiopoetin-1 was significantly lower in the medium of miR-92a over-expressing cells, however VEGF secretion did not change. We conclude that overexpression of miR-92a in ADSC suppresses angiogenic properties of these cells by down-regulation of HGF and angiopoetin-1 secretion, therefore miR- 92a could be considered as a promising target for the modulation of ADSC angiogenic potential both in vivo and ex vivo.