Chinese Journal of Tissue Engineering Research ›› 2019, Vol. 23 ›› Issue (21): 3281-3288.doi: 10.3969/j.issn.2095-4344.1742

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Roles of ROCK signaling in proliferation and paracrine action of hypoxia-induced c-Kit+ bone marrow mesenchymal stem cells

Shao Zhongming, Wang Keke, Liao Xiaomin, Ha Yanping, Li Rujia, Shen Zhihua, Jie Wei   

  1. Department of Pathology, School of Basic Medicine, Guangdong Medical University, Zhanjiang 524023, Guangdong Province, China
  • Revised:2019-01-21 Online:2019-07-28 Published:2019-07-28
  • Contact: Jie Wei, PhD, Professor, Department of Pathology, School of Basic Medicine, Guangdong Medical University, Zhanjiang 524023, Guangdong Province, China
  • About author:Shao Zhongming, Master candidate, Department of Pathology, School of Basic Medicine, Guangdong Medical University, Zhanjiang 524023, Guangdong Province, China. Wang Keke, Doctorate candidate, Department of Pathology, School of Basic Medicine, Guangdong Medical University, Zhanjiang 524023, Guangdong Province, China. Shao Zhongming and Wang Keke contributed equally to this work.
  • Supported by:

    the National Natural Science Foundation of China, No. 81670254 (to JW); the Science and Technology Planning Project of Guangdong Province, No. 2016A020214016 (to JW); and the YangFan Plan of Guangdong Province, No. 4YF16007G (to JW)

Abstract:

BACKGROUND: Hypoxia stimulates the proliferation of bone marrow mesenchymal stem cells, but the specific mechanism is still unclear. The Rho-associated coiled-coil containing kinases (ROCK) signaling has an important influence on cell proliferation, migration and apoptosis. Few studies have been reported on the effect of ROCK signaling on the biological functions of bone marrow mesenchymal stem cells.
OBJECTIVE: To analyze the effect of ROCK signaling on the hypoxia-induced proliferation and paracrine of c-Kit+ bone marrow mesenchymal stem cells.
METHODS: Rat bone marrow mesenchymal stem cells derived from the rat femur were obtained by adherent method, and the c-Kit+ subpopulation was sorted by magnetic activated cell sorting. Cells were cultured under normoxia (21% O2) and hypoxia (2% O2). After treatment with an ROCK signal inhibitor Fasudil (10 μmol/L), western blot was used to detect the expression of p-MLC (T18/S19), MLC, p-MLC2(T18/S12)/MLC2, PCNA and cell cycle related proteins. The cell proliferation was analyzed by cell counting, the cell cycle was detected using flow cytometry, and the changes of vascular endothelial growth factor, transforming growth factor β1 and basic fibroblast growth factor in the cell supernatant were detected by ELISA. 
RESULTS AND CONCLUSION: c-Kit+ subpopulation were successfully isolated from rat bone marrow mesenchymal stem cells. Compared with normoxia, hypoxia treatment significantly down-regulated MLC expression, up-regulated p-MLC(T18/S19) expression and therefore increased the ratio of p-MLC(T18/S19)/MLC2. Meanwhile, hypoxia promoted the proliferation of c-Kit+ bone marrow mesenchymal stem cells, as evidenced by the increase in cell number and PCNA protein expression. Fasudil inhibited the hypoxia-induced the proliferation of c-Kit+ bone marrow mesenchymal stem cells, arrested the cell cycle at S phase, inhibited CDK2 and CDK4 and increased p16 expression. Hypoxia significantly promoted the secretion of vascular endothelial growth factor, transforming growth factor β1 and basic fibroblast growth factor by c-Kit+ bone marrow mesenchymal stem cells, and Fasudil attenuated hypoxia-induced vascular endothelial growth factor and transforming growth factor β1 expression but astonishingly upregulated basic fibroblast growth factor level. These results indicate that hypoxia promotes cell proliferation and paracrine of angiogenic factors and activates ROCK signaling in c-Kit+ bone marrow mesenchymal stem cells; Fasudil inhibits hypoxia-induced proliferation and expression of angiogenic factors in c-Kit+ bone marrow mesenchymal stem cells, suggesting that ROCK signaling plays a positive role in the proliferation and paracrine of c-Kit+ bone marrow mesenchymal stem cells.

Key words: ROCK signal, Fasudil, hypoxia, stem cells, bone marrow mesenchymal stem cells, c-Kit, cell proliferation, paracrine, National Natural Science Foundation of China

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