Effect of Cross‐Linked Hyaluronate Scaffold on Cartilage Repair: An In Vivo Study

OBJECTIVE: To determine the safety and effectiveness of a cross‐linked sodium hyaluronate (CHA) scaffold in cartilage repair. METHODS: Physicochemical properties of the scaffold were determined. The safety and effectiveness of the scaffold for cartilage repair were evaluated in a minipig model of a full‐thickness cartilage defect with microfracture surgery. Postoperative observation and hematological examination were used to evaluate the safety of the CHA scaffold implantation. Pathological examination as well as biomechanical testing, including Young's modulus, stress relaxation time, and creep time, were conducted at 6 and 12 months postsurgery to assess the effectiveness of the scaffold for cartilage repair. Furthermore, type II collagen and glycosaminoglycan content were determined to confirm the influence of the scaffold in the damaged cartilage tissue. RESULTS: The results showed that the routine hematological indexes of the experimental animals were within the normal physiological ranges, which confirmed the safety of CHA scaffold implantation. Based on macroscopic observation, it was evident that repair of the defective cartilage in the animal knee joint began during the 6 months postoperation and was gradually enhanced from the central to the surrounding region. The repair smoothness and color of the 12‐month cartilage samples from the operation area were better than those of the 6‐month samples, and the results for the CHA scaffold implantation group were better than the control group. Greater cell degeneration and degeneration of the adjacent cartilage was found in the implantation group compared with the control group at both 6 and 12 months postoperation, evaluated by O'Driscoll Articular Cartilage Histology Scoring. Implantation with the CHA scaffold matrix promoted cartilage repair and improved its compression capacity. The type II collagen level in the CHA scaffold implantation group tended to be higher than that in the control group at 6 months (2.33 ± 1.50 vs 1.68 ± 0.56) and 12 months postsurgery (3.37 ± 1.70 vs 2.06 ± 0.63). The GAG content in the cartilage of the control group was significantly lower than that of the experimental group (2.17 ± 0.43 vs 3.64 ± 1.17, P = 0.002 at 6 months and 2.27 ± 0.38 vs 4.12 ± 1.02, P = 0.002 at 12 months). Type II collagen and glycosaminoglycan content also demonstrated that CHA was beneficial for the accumulation of both these vital substances in the cartilage tissue. CONCLUSIONS: The CHA scaffold displayed the ability to promote cartilage repair when applied in microfracture surgery, which makes it a promising material for application in the area of cartilage tissue engineering.