Orbital Shaking Promoted Vascular Elastogenesis in Cultured Rat Aortic Smooth Muscle Cells

Abstract

[Background] Vascular elasticity is vital for the functions of arterial vessels. The lack of vascular elasticity in arterial walls induces fatal cardiovascular diseases including aortic aneurysms.It has already been known that elasticity is determined by the components such as elastin and collagen, and that blood pulsatile flow affects their expressions. However, this mechanism has not clarified well.Iwasaki et al successfully fabricated three layered bioengineered vessels that had similar elasticity to native arteries with fetal bovine aortic cells using a pulsatile bioreactor regulated flow rate and pressure, and suggested the mechanical stress promoted vascular elastogenesis. In order to clarify the mechanism of arterial elastic fiber formation , we developed rat tissue engineered vessel with physical stimulation by using an orbital shaker.[Method] At first, we isolated rat aortic smooth muscle cells (ASMC) from rat fetuses at embryonic 21 day and harvested them on a polyglycolic acid (PGA) sheet of 2cm×2cm×1mm. After incubation of one week in a CO2 incubator, this sheet was wrapped around a silicone tube. After one week incubation, the cell /PGA construction was placed in a flask. This flask was placed in a CO2 incubator on an orbital shaker, which provided gentle agitation at 50rpm and incubated for two weeks. We histologically and genetically analyzed the cell /PGA construction.[Results] Under orbital shaking condition, cells seemed to localize and maintain their phenotypes. Moreover, elastin deposit was formed in the cell-localized area. Total RNA successfully extracted from the cell/PGA construction. The expression levels of elastin mRNA seemed to be higher under orbital shaking condition than non-shaking condition. [Conclusion] Our results suggested that orbital shaking promoted vascular elastogenesis of the cell /PGA construction and also physical stress by shaking incubation tended to stimulate vascular elastic fiber formation.