Hepatocyte growth factor/c-met promotes proliferation, suppresses apoptosis, and improves matrix metabolism in rabbit nucleus pulposus cells in vitro

The etiology of intervertebral disc (IVD) degeneration is closely related to apoptosis and extracellular matrix degradation in nucleus pulposus (NP) cells. These defects in NP cells are induced by excessive external stressors such as reactive oxygen species (ROS) and inflammatory cytokines. Recently, hepatocyte growth factor (HGF) has been shown to repair damage in various diseases through anti-apoptotic and anti-inflammatory activity. In this study, we investigated the effects of HGF on NP cell abnormality caused by ROS and inflammatory cytokines by using primary NP cells isolated from rabbit IVD. HGF significantly enhanced the proliferation of NP cells. Apoptosis of NP cells induced by H2O2 or TNF- was significantly inhibited by HGF. Induction of mRNA expression of the inflammation mediators cyclooxygenase-2 and matrix metalloproteinase-3 and -9 by TNF- was significantly suppressed by HGF treatment. Expression of c-Met, a specific receptor for HGF, was confirmed in NP cells and was increased by TNF-, suggesting that inflammatory cytokines increase sensitivity to HGF. These findings demonstrate that activation of HGF/c-Met signaling suppresses damage caused by ROS and inflammation in NP cells through multiple pathways. We further suggest the clinical potential of HGF for counteracting IVD degradation involved in NP cell abnormalities. (c) 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:709-716, 2016.