Pre-conditioning of smooth muscle cells via induction of the heat shock response limits proliferation following mechanical injury

Arterial smooth muscle cell (SMC) proliferation is a significant component of post-angioplasty restenosis. We evaluated whether pre-conditioning of SMCs, via induction of the heat shock respone prior to actual physical injury, would result in an alteration in cell proliferation following injury. Rat aortic SMCs were pretreated with either chemical or thermal heat shock inducers and then subjected to scrape-wound injury in vitro. Cell proliferation at 24 hrs was measured via ³H-thymidine (Tdr) incorporation and compared with scrape wounded unstressed controls. A significant decline in cell proliferation post scrape-wound injury was observed for both chemical and thermal heat shock pre-conditioned cultures, compared to untreated controls. Increased expression of heat shock protein 72 was confirmed serially throughout the 24 hr study period for both chemical and thermal inducers. Despite reduced proliferation heat shocked cells remained viable as evidenced by fluorescent cell viability assay and preserved migration. Pre-conditioning of SMCs through induction of the heat shock response prior to physical injury may be a useful approach to limit aggressive proliferation observed with mechanical revascularization injury.