Poly(lactide-co-glycolide) microspheres as a moldable scaffold for cartilage tissue engineering.

This study demonstrates the use of biodegradable poly(lactide-co-glycolide) (PLG) microspheres as a moldable scaffold for cartilage tissue engineering. Chondrocytes were delivered to a cylindrical mold with or without PLG microspheres and cultured in vitro for up to 8 weeks. Cartilagenous tissue formed using chondrocytes and microspheres maintained thickness, shape, and chondrocyte collagen type II phenotype, as indicated by type II collagen staining. The presence of microspheres further enhanced total tissue mass and the amount of glycosaminoglycan that accumulated. Evaluation of microsphere composition demonstrated effects of polymer molecular weight, end group chemistry, and buffer inclusion on tissue-engineered cartilage growth. Higher molecular weight PLG resulted in a larger mass of cartilage-like tissue formed and a higher content of proteoglycans. Cartilage-like tissue formed using microspheres made from low molecular weight and free carboxylic acid end groups did not display increases in tissue mass, yet a modest increased proteoglycan accumulation was detected. Microspheres comprised of PLG with methyl ester end groups yielded a steady increase in tissue mass, with no real increase in matrix accumulation. The microencapsulation of Mg(OH)(2) had negative effects on tissue mass and matrix accumulation. The data herein reflect the potential utility of a moldable PLG-chondrocyte system for tissue-engineering applications.

A novel injectable approach for cartilage formation in vivo using PLG microspheres.

This study documents the use of biodegradable poly(lactide-co-glycolide) (PLG) microspheres as a novel, injectable scaffold for cartilage tissue engineering. Chondrocytes were delivered via injection to the subcutaneous space of athymic mice in the presence and absence of PLG microspheres. Tissue formation was evaluated up to 8 weeks post-injection. Progressive cartilage formation was observed in samples containing microspheres. The presence of microspheres increased the quantity of tissue formed, the amount of glycosaminoglycan that accumulated, and the uniformity of type II collagen deposition. Microsphere composition influenced the growth of the tissue engineered cartilage. Higher molecular weight PLG resulted in a larger mass of cartilage formed and a higher content of proteoglycans. Microspheres comprised PLG with methyl ester end groups yielded increased tissue mass and matrix accumulation, but did not display homogenous matrix deposition. The microencapsulation of Mg(OH)2 had negative effects on tissue mass and matrix accumulation. Matrix accumulation, cell number, and tissue mass were unchanged by microsphere size, but larger microspheres increased the frequency of central necrosis in implants. The data herein reflect the promising utility of an injectable PLG-chondrocyte system for tissue engineering applications.