Changes in the structure and biosynthetic activity of porcine heart valve leaflets under elevated pressure

Fresh porcine heart aortic valves were harvested and cultured for 48 hrs under different pressure conditions. Techniques including routine H&E, Movat´s staining, a SMC actin immunohistochemistry, and ³H-proline radiolabeling were performed. Results showed that the three-layered structure became less distinct after incubation; this was true for both control and pressure groups. The number of α-SMC actin immunoreactive cells decreased in both elevated pressure and control groups; however, the pulsatile pressure group generally retained significantly more actin than control. Elevated pressure leaded to increased protein synthesis; this increase was proportional to the magnitude of applied pressure. Movat´s staining showed less dense collagen in control than in the pressure group. Cell morphology was also different: the pressure group had a higher percentage of elongated cells, and most cells attach well to surrounding matrix; while in the control group, cells are more tended to be rounded and detached from matrix.