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Background: The release of a wide array of endothelial progenitor cell (EPC) sheet-secreted paracrine factors is central to the mechanism by which these cells contribute to tissue repair. The purpose of this study was to fabricate BM-EPC sheet and conduct preliminary investigation on the paracrine effect of SDF-1ɑ about the role of the stromal cell-derived factor-1α (SDF-1α)/CXCR4 axis in the form of tubular structures from BM-EPCs sheet.Methods: EPCs derived from rat bone marrow (BM-EPC) were identified and isolated by the cell-surface markers CD34/CD133/VE-cadherin/KDR using flow cytometry, as well as by dual affinity for acLDL and UEA-1. Single-cell suspensions were seeded on temperature-responsive cell culture dishes. After 7 days of incubation, the BM-EPC cells were easily harvested as cell sheets, and a series of biochemical experiments were performed in vitro. The expression levels of SDF-1α/CXCR4 axis-associated genes and proteins were examined using RT‑qPCR and western blot analysis, and enzyme-linked immunosorbent assay (ELISA) was applied to determine the concentrations of VEGF, EGF and SDF-1α in the cell culture medium.Results: The BM-EPC cell sheets were successfully harvested. Moreover, BM-EPC cell sheets have superior proliferation and tube formation activity when compare with single cell suspension. When capillary-like tube were formed from EPCs sheets, the releasing of paracrine factors such as VEGF, EGF, and SDF-1ɑ were increasing. To drive the tube formation of BM-EPCs sheets, our mechanism research showed that the activation of PI3K/AKT/eNOS pathway since the phosphorylation of protein CXCR, PI3K, AKT and eNOS were increasing. Conclusion: BM-EPC cell sheets have superior proliferation and tube formation activity that can be used for tissue repair. The strong ability to secrete paracrine factors was be related to the SDF-1α/CXCR4 axis through PI3K/AKT/eNOS pathway. |
