Effects of cyclic strain on morphology and growth of vascular smooth muscle cells

Objective:To investigate the effects of cyclic strain on the morphology and growth of vascular smooth muscle cells(VSMCs). Methods: A pulsatile membrane cyclic strain system was used to perform cyclic strain on VSMCs from adult SD rats. Microscopy and computer image capture system were used to investigate morphological change in VSMCs. The growth of VSMCs and their DNA synthesis were indicated by 3HTdR method. Results: Under 14% cyclic strain, VSMCs re-aligned gradually and were finally vertical to the direction of stress; the shape index decreased. However, the spreading area, perimeter and long axis of stretched VSMCs increased within 6 h, then decreased to a relatively stable level from 12 to 24 h. The growth and 3H thymidine incorporation of VSMCs under 8% cyclic strain were arrested, but accelerated under 14% cyclic strain.The 3H thymidine incorporation had a significant difference in 12 h and increased by 1.4-fold and 1.8-fold in 24 and 48 h respectively compared with control group. Conclusion: The cyclic strain not only affects the morphology of VSMCs, but leads to rearrangement of VSMCs. It can inhibit cell growth under physiological condition but promote cell growth beyond physiological condition in cultured VSMCs.