Abstract 582: Cardiac Fibroblast Bridges Conduct Electrical Signals between Myocyte Islands.
In this study, the electrophysiological properties of fibroblasts cocultured with cardiomyocytes were characterized using a novel cell micropatterning system. In the infarct area of a heart, the cardiac fibroblasts are known to increase collagen deposition leading to fibrosis. The fibrous tissue acts as an insulator in the damaged area and thus modulates local electrical signal conduction. This is fibroblast’s “passive role” in myocardium signal conduction. However, studies have shown that when placed in physical contact with viable myocytes, fibroblasts can form functional gap junctions and conduct electrical signal. This coupling phenomenon has been suggested as playing a role in re-entrant arrhythmias that occur in the infarct to healthy tissue border zone but there is still little known about the actual involvement fibroblasts have in the heart’s electrical communication. Our interest is in designing an in vitro model using cell micropatterning to study and characterize the electrophysiological properties of fibroblasts cocultured with myocytes. In this study we evaluate the hypothesis that fibroblast will conduct electrical signal between myocytes but this conduction will be restricted by the number of fibroblast involved. A combination of photolithography and laser micropatterning is used to achieve cell micropatterning. Polydimethyl siloxane (PDMS) stencils, created by photolithography, are used to form the myocyte islands and laser micropatterning is used to form the fibroblast cell bridge connecting the myocyte islands. Various PDMS stencils which varied the distance between the myocyte islands were made enabling us to form fibroblast bridges of various lengths (50 um to 500 um). Dual patch clamp experiments were performed to evaluate action potential propagations along the fibroblast bridge and characterize its electrical capabilities. With our laser micropatterning we were able to form fibroblast conducting bridges up to 390 um. In conclusion, fibroblast bridges can conduct electrical signals over short distances however with the increase of the fibroblast bridge length, signal propagation delay also increased. This conduction delay phenomenon observed in vitro could explain the cause of reentrant arrhythmias in vivo.