Biocompatibility and Biodegradation of Poly(D,L-lactic-co-glycolic acid) 90/10: In Vitro and In Vivo Assays

There has been concern regarding the long-term safety of the current drug-eluting stents (DESs) using "durable-polymer" technology. On this background, a number of second generation DESs using bioabsorbable-polymer are put under tests. In our study, we assessed the in vitro degradation and biocompatibility of poly (D,L-lactic- co-glycolic acid) (PLGA) 90L/10G, as a biodegradable material. In vitro degradation characteristics were evaluated by measuring decrease in the mass loss of PLGA films. In order to evaluate the cytotoxicity of PLGA, calf vascular smooth muscle cells (VSMCs) were incubated with PLGA films. Cells that were incubated in culture medium alone were used as controls. We determined the cell viability by a 3-(4,5-dimethylthiazol- 2-yl)-2, 5 diphenyltetrazolium bromide (MTT) assay and the distribution of cell cycle phases by flow cytometry. The morphology of VSMCs seeded on PLGA films was observed by scanning electron microscopy technique. PLGA films were inserted into the anterior wall of the left ventriculators and circumflex arteries of 6 dogs that served as test animals. The animals were sacrificed after 2 weeks, 1 month, and 2 months. Pathohistological and ultrastructural changes in the myocytes and vasculature were examined by light and electron microscopy. High-molecular-weight PLGA degraded slowly in the first 4 months. There was 10% mass loss at the 120th day and rapid mass loss thereafter. There were no differences in the cell viability and distribution of cell cycle phases between the control and PLGA groups. The cells attached favourably and grew well on the films. A slight inflammatory change occurred with regard to the pathohistology and ultrastructure of the myocardium and vessels. Thus, the low cytotoxicity, good histocompatibilty, and biodegradable nature of PLGA 90/10 make it a promising material as a useful vehicle for locally administered drugs.