Optimisation of polymer scaffolds for retinal pigment epithelium (RPE) cell transplantation.

Abstract

To evaluate a variety of copolymers as suitable scaffolds to facilitate retinal pigment epithelium (RPE) transplantation. Five blends of poly(l-lactic acid) (PLLA) with poly(d,l-lactic-glycolic acid) (PLGA) were manufactured by a solid-liquid phase separation technique. The blends were 10:90, 25:75, 50:50, 75:25 and 90:10 (PLLA:PLGA). All blend ratios were validated by nuclear magnetic resonance spectroscopy. Samples of polymer blends were coated with laminin. Coated and uncoated blends were seeded with a human RPE cell line. Cell attachment, viability and retention of phenotype were assessed. As the lactide unit content increased pore size generally became smaller. The 25:75 PLLA:PLGA blend was the most porous (44%) and thinnest (134 μm) scaffold produced. ARPE-19 cells retained an appropriate phenotype with minimal cell death for up to 4 weeks in vitro. Cell density was maintained on only one of the fabricated ratios (25% PLLA:75% PLGA). A consistent decrease in apoptotic cell death with time was observed on coated samples of this blend. A decrease in polymer thickness concomitant with an increase in porosity characteristic of degradation was observed with all polymer blends. This study demonstrates that a 25:75 copolymer blend of PLLA:PLGA is a potentially useful scaffold for ocular cell transplantation.