[Effect of mechanical stimulation combined with inductive factors on tissue engineered cartilage].

OBJECTIVE: Mechanical stimulation and inductive factors are both crucial aspects in tissue engineered cartilage. To evaluate the effects of mechanical stimulation combined with inductive factors on the differentiation of tissue engineered cartilage.

METHODS: Bone marrow mesenchymal stem cells (BMSCs) were isolated from newborn porcine (aged 7 days and weighing 3-6 kg) and expanded in vitro. The BMSCs at passage 2 were seeded onto a scaffold of poly (lactic-co-glycolic acid) (PLGA) in the concentration of 5 x 10(7)/mL to prepare cell-scaffold composite. Cell-scaffold composites were cultivated in a medium with chondrocyte-inducted factors (group A), in a vessel with mechanic stimulating only (group B), or mechanic stimulating combined with chondrocyte-inducted factors (group C) (parameters of mechanics: 1 Hz, 0.5 MPa, and 4 hours/day). Cell-scaffold composite and auto-cartilage served as positive control (group D) and negative control (group E), respectively. After 4 weeks of cultivation, the thickness, elastic modulus, and glycosaminoglycan (GAG) content of composites were measured. Additionally, BMSCs chondrogenic differentiation was assessed via real-time fluorescent quantitative PCR, immunohistochemistry, and histological staining.

RESULTS: The thickness, elastic modulus, and maximum load in group C were significantly higher than those in groups A and B (P < 0.05). In groups A, B, and C, cartilage lacuna formation, GAG expression, and positive results for collagen type II were observed through HE staining, Safranin-O staining, and immunohistochemistry staining. The dyeing depth was deeper in group A than in group B, and in group C than in groups A and B; group C was close to group E. The GAG content in group C was significantly higher than that in groups A and B (P < 0.05). Real-time fluorescent quantitative PCR revealed that mRNA expressions of collagen type I, collagen type II, and GAG in group C were significantly higher than those in groups A and B (P < 0.05), and in group A than in group B (P < 0.05).

CONCLUSION: Mechanical stimulation combined with chondrocyte inductive factors can enhance the mechanical properties of the composite and induce higher expression of collagen and GAG of BMSCs.