Genetically enhanced engineering of meniscus tissue using ex vivo delivery of transforming growth factor-β1 complementary deoxyribonucleic acid

To investigate the use of a scaffold seeded with genetically modified meniscal cells or mesenchymal stem cells (MSCs) for the healing of meniscal lesions, primary meniscus cells and bone marrow-derived MSCs were isolated from bovine calves and transduced with first-generation adenoviral vectors encoding green fluorescent protein, luciferase, or transforming growth factor (TGF)-β1 complementary deoxyribonucleic acid (cDNA). The genetically modified cells were seeded in type I collagen-glycosaminoglycan (GAG) matrices and transplanted into tears of the avascular zone of bovine menisci. After 3 weeks of in vitro culture, constructs and repair tissues were analyzed histologically, biochemically, and using reverse transcriptase polymerase chain reaction. Recombinant adenovirus readily transduced meniscal cells and MSCs, and transgene expression remained high after the cells were incorporated into collagen-GAG matrices. Transfer of TGF-β1 cDNA increased cellularitiy and the synthesis of GAG/DNA [μg/μg]. It also led to stronger staining for proteoglycans and type II collagen and enhanced expression of meniscal genes. Transplantation of the TGF-β1 transduced constructs into meniscal lesions of the avascular zone resulted in filling of the lesions with repair tissue after 3 weeks of in vitro culture. These results indicate that TGF-β1 cDNA delivery may affect cell-based meniscus repair approaches in vivo.