Activity of smooth muscle cells after short-term heating/stretch-fixing up to 96 hours

We studied the influence of short-term heating/stretch-fixing stimulus on smooth muscle cells in vitro to determine the condition of optimum vascular dilatation for our novel angioplasty. A short-term thermal angioplasty named Photo-Thermo Dynamic Balloon (PTDB) has been proposed for stenotic artery treatment. Stretch-fixed smooth muscle cells after PTDB dilatation was reported previously. This formation would be a risk of restenosis because of enhancement in smooth muscle cells’ migration ability. To estimate migration ability after short-term heating/stretch-fixing, we studied respiratory activity of smooth muscle cells up to 96 hours in vitro. Smooth muscle cells were heated (50oC or 60oC, 15 s) with stretching (0 or 40%), and fixed. We measured respiratory activity of smooth muscle cells and alive cell number at 48 and 96 hours after short-term heating/stretch-fixing. A WST-8 assay solution and nuclear stainings (Hoechst 33342 and Propidium Iodide) were used for measurement of the respiratory activity and alive cell number, respectively. The absorbance value at 450 nm after WST-8 assay divided by the alive cell number was used for activity evaluation. We obtained that the respiratory activity of smooth muscle cells after short-term heating/stretch-fixing was drastically decreased in the case of 60oC heating. In the case of 50oC heating, the respiratory activity of smooth muscle cells was decreased more gradually than that of 60oC. We think that heating smooth muscle cells at 60oC in PTDB dilatation might sufficiently suppress the cell migration. Chronic restenosis suppression might be suggested in that case.