Electrical Stimulation of Cellular Response: Responses and Mechanisms

摘要

Project objectives for the first year include: (1) Define the relationship between physiologic electrical currents and the rate of biosynthesis of extracellular matrix proteins by bovine fibroblasts and chondrocytes. (2) Determine the extent of cellular proliferative response to the same physiologically relevant electrical stimulus. (3) Set up and calibrate a real-time fluorometric assy of intracellular (NAD(P)h using microfluorometric techniques. With a in-vitro system which minimized the sample-to-sample variation by using a isogenetic cell population at a uniform cell density, we observed that: (1) Bovine (and Human) fibroblasts and bovine chondrocytes respond to low frequency sinusoidal electric current by altering the rate of biosynthesis of extracellular matrix structural macromolecules. This effort was dependent on stimulus frequency and amplitude. (2) The sensitivity of the fibroblasts to the fields was found to depend on the orientation of the cells in the direction of the field. Cells oriented such that their major axis was aligned in the direction of the electric field responded to weaker electric currents than those aligned perpendicular to the field. (3) We have also observed that while chondrocytes in organ culture do not change their biosynthetic behavior in response to 10 Hz a.c. current densities up to 1 ma/sq.cm, chondrocytes in hydrated collagen gels respond to current densities as low as 50 a/s2.cm at 20 Hz.