Functions and mechanisms of intermittent negative pressure for osteogenesis in human bone marrow mesenchymal stem cells.

The present study aimed to determine the mechanism by which low-intensity intermittent negative pressure affects the differentiation and proliferation of human mesenchymal stem cells (MSCs). Alkaline phosphatase (ALP) activity, type I collagen and vascular endothelial growth factor (VEGF) were detected to analyze differentiation. MTT and flow cytometry were employed to measure proliferation and apoptosis. Western blot analysis was used to examine endoplasmic reticulum (ER) stress-associated factors. This study was divided into two groups, including a normal group (without any treatment) and vacuum group (treated with a vacuum). There was a significant decrease in the proliferation of cells in the vacuum group. The number of cells in S phase was reduced significantly, while the rate of apoptosis and the activity of ALP were markedly increased under vacuum conditions. Expression of collagen type I and VEGF was significantly increased, and the ratio of osteoprotegrin to osteoprotegrin ligand was decreased significantly in the vacuum group. ER stress-associated proteins, p-PRKR-like ER kinase, inositol-requiring enzyme 1 and cleaved activating transcription factor 6, as well as the downstream factors, were activated when treated with negative pressure. In conclusion, treatment with low-intensity and intermittent negative pressure may inhibit the proliferation of MSCs and trigger ER stress-associated cellular apoptosis, further enhancing osteogenesis activity and inducing differentiation to osteoblasts. [ABSTRACT FROM AUTHOR]