Biophysical Examination of Vascular Smooth Muscle Cell Interaction with PLA and PLGA Polymer Surfaces

INTRODUCTION: Vascular tissue engineering has yet to produce a viable vessel replacement that can be used in humans. Biocompatible scaffolds are often used, onto which cells are seeded, and grown in a bioreactor under pulsatile pressure (1). Two polymers, PLA (polylactic acid) and PLGA (poly(lactide-co-glycolide)) are commonly used as the biomaterial scaffold. Despite recent advances in the technique, bioengineered vascular grafts do not appear to produce important components of the vessel wall, particularly elastin (2). At present, little is known about the effect of biomaterial surfaces on cell behaviour and matrix synthesis. The aim of this project is to begin to identify cues that regulate cell attachment, migration and proliferation, and by altering the biomaterials, encourage cells to engineer their own matrix. METHODS: 22x22 mm glass coverslips were thinly coated with 0.3% (w/v in chloroform) solutions of PLA or PLGA. The thickness and surface uniformity of the polymer films on the coverslips was determined using spectroscopic ellipsometry. Human vascular smooth muscle cells (VSMCs) were obtained using the explant technique and used between passages 2-8. The polymer coated slides were placed in 6-well plates and VSMCs seeded at a density of 1 x 10 4 cells/well, in 2ml DMEM with or without 10% bovine foetal serum. Identical conditions were used with uncoated glass coverslips or tissue culture plastic as controls. The behaviour of the cells was monitored using time-lapse video microscopy (Nikon) for a period of 24 hours. The expression of matrix genes was assessed by real - time quantitative polymerase chain reaction (RQ- PCR). The expression of Fibronectin -1, Elastin, Vitronectin, Collagen type I and IV, Versican, Fibrillin and Myosin heavy chain II (probes all assays-on-demand, Applied Biosystems) were all assessed with β-actin as the endogenous control. RESULTS: