Effect of cobalt chloride-induced hypoxia on proliferation of human umbilical cord-derived mesenchymal stem cells and related gene and protein expressions / 中国组织工程研究

ABSTRACT

BACKGROUND:Cobalt chloride (CoCl2) may promote the proliferation of human umbilical cord-derived mesenchymal stem cels (hUC-MSCs) in a time- and concentration-dependent manner, and meanwhile, CoCl2 can regulate the expression of genes and proteins in hUC-MSCs. OBJECTIVE:To explore the effects of CoCl2 induced-hypoxia on the proliferation of hUC-MSCs and gene and protein expressions in hUC-MSCs, thereby establishing an effective method for MSCs culture and amplificationin vitro. METHODS: hUC-MSCs were extracted using tissue explant method. Under hypoxia conditions induced by CoCl2 (0, 100, 150, 200, 250 μmol/L) for different periods (0, 1, 2, 3, 4 days), flow cytometry was used to identify cel surface-associated antigens; cel counting kit-8 was used to detect cel proliferation; RT-PCR was used to determine levels of hypoxia inducible factor-1α, inducible nitric oxide synthase, stromal cel-derived factor-1, interleukin-6, transforming growth factor-β mRNA; western blot assay was used to detect protein expression of hypoxia inducible factor-1α. RESULTS AND CONCLUSION:The cels were positive for CD29, CD73, CD90, CD105, while negative for CD31, CD14, CD34, CD45, CD11b, HLA-DR. Moreover, the antigen expression was not affected by CoCl2 induced-hypoxia. CoCl2 induced-chemical hypoxia could promote the proliferation of hUC-MSCs in a time- and concentration-dependent manner. RT-PCR results showed thatunder hypoxia, hypoxia inducible factor 1α, inducible nitric oxide synthase and stromal cel-derived factor-1 mRNA expressions were significantly up-regulated, but interleukin-6 and transforming growth factor-β mRNA expressions were down-regulated significantly (P < 0.05). Additionaly, the protein expression of hypoxia inducible factor 1α was increased under hypoxia conditions. These findings indicate that CoCl2 induced-hypoxia environment may promote the proliferation of hUC-MSCs and the optimal concentration of CoCl2 is 200μmol/L. However, a higher concentration of CoCl2 (≥ 250μmol/L) inhibits the proliferation of hUC-MSCs, and the mechanism may be related to the increase of hypoxia inducible factor-1α at protein and mRNA levels.