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  2. CoCl2 -simulated hypoxia potentiates the osteogenic differentiation of fibroblasts derived from tympanosclerosis by upregulating the expression of BMP-2

CoCl2 -simulated hypoxia potentiates the osteogenic differentiation of fibroblasts derived from tympanosclerosis by upregulating the expression of BMP-2

  • Cell Biol Int. 2022 Sep;46(9):1423-1432. doi: 10.1002/cbin.11845.
Chen Zhang 1 Yang-Wenyi Liu 1 2 Min Chen 1 2 Shiyao Min 1 2 Jiabao Mao 1 2 Qin Li 3 Zhangcai Chi 1 2
Affiliations

Affiliations

  • 1 ENT Institute and Department of Otolaryngology, Eye & ENT Hospital, Fudan University, Shanghai, China.
  • 2 NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, PR China.
  • 3 Stomatology Department, Eye & ENT Hospital, Fudan University, Shanghai, China.
Abstract

Tympanosclerosis (TS) is a result of long-standing middle ear inflammation characterized by fibroblasts ossification. Fibrosis is the last revertible stage in the progress of middle ear inflammation to TS. It was hypothesized that chronic hypoxia could be modulating fibrosis, which in turn additionally further aggravated hypoxia via decreasing oxygen diffusion. However, the effects of hypoxia on osteoinductive activity of fibroblasts have not been explored. Herein, we purposed to explore the role of hypoxia in osteogenic differentiation of fibroblasts derived from TS. The expression of bone morphogenetic protein-2 (BMP-2), hypoxia-inducible factor-1α (HIF-1α), and Vimentin in the human surgical specimens of tympansclerosis was investigated by immunofluorescent staining. Furthermore, cultured fibroblasts were stratified into the following study groups: control, 25, 50, and 100 μM cobaltous chloride (CoCl2 ) group. BMP-2, as well as HIF-1α levels of expression were detected via western blotting and immunofluorescence analysis. We found that the expression of BMP-2 and HIF-1α was significantly upregulated in TS tissues and these fibroblasts, which was vimentin positive surrounding sclerotic plaques, were also expressing HIF-1α positive. The results also demonstrated that CoCl2 treatment increased nuclear HIF-1α protein level in the fibroblast. Furthermore, treatment with CoCl2 significantly increased BMP-2 expression and remarkably elevated alkaline phosphatse activity and the mineralized nodules area. These data illustrate that hypoxia may play an osteogenic role in TS fibroblasts via the elevated expression of a possible osteogenic factor, BMP-2.

Keywords

fibroblasts; hypoxia; ossification; tympanosclerosis.

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