Chondrogenesis of myoblasts in biodegradable poly-lactide-co-glycolide scaffolds

Myoblasts are considered to be an alternative cell source for cell-based meniscal repair due to their multiple differentiation potentials. This study addresses the chondrogenic differentiation of myoblasts seeded into poly-lactide-co-glycolide (PLGA) scaffolds following implantation in a subcutaneous pocket of nude mice. Canine myoblasts isolated from a Beagle were expanded and seeded into PLGA scaffolds and cultured in cartilage-derived morphogenetic protein-2 (CDMP-2) and transforming growth factor-β1 (TGF-β1)-containing medium for 2 weeks in vitro. The constructs were implanted into a subcutaneous pocket of 24 combined immunodeficiency mice and harvested after 8 and 12 weeks, respectively. Hematoxylin and eosin staining of the sections of the engineered cartilage at 8 and 12 weeks revealed the regeneration of fibrocartilage. Immunohistochemical staining confirmed a similar distribution of collagen type Ⅱ in the engineered cartilage as the normal meniscus. At 12 weeks, expression of mRNAs for type Ⅰ collagen, type Ⅱ collagen and aggrecan was detected by RT-PCR. The compressive moduli of engineered cartilage reached 85.72% of the normal meniscus at 12 weeks, with a high level of glycosaminoglycan (GAG) content (no statistical difference from normal). Myoblast-seeded PLGA scaffolds express a stable chondrogenic phenotype in a heterotopic model of cartilage transplantation and represent a suitable tool for tissue engineering of cartilage.