Abstract: Objective To explore the feasibility of low-molecule-weight hydrogel M2 and cross-lincked hyaluronic acid （HA） as injectable materials for cartilage tissue engineering in nude mice. Methods The auricular chondrocytes of newborn pig were isolated and expanded. The cells were mixed with M2 hydrogel in 50×10^6 cells/mL and 100×10^6 cells/mL, and were mixed with HA in 100 ×10^6 cells/mL, followed by subcutaneous injection into nude mice. M2 hydrogel and HA were also injected as control groups. After 8 weeks, the samples were harvested and evaluated for cartilage formation by gross view, histochemical examination, wet weight test, mechanical analysis and glycosaminoglycan （GAG） quantification. Results All three groups formed cartilage-like tissues. Samples in M2 group with high cell density （100×10^6 cells/mL） were the largest in size with stiffest texture, smoothest surface, and most abundant lacuna structures. Samples in M2 group with low cell density （50 ×10^6 cells/mL） also formed cartilage-like tissue with stiff texture, but their size shrank obviously; HA group, however, formed immature cartilaginous tissue with poor rigidity, cellularization and cartilage specific matrix expression. The corresponding quantitative data further demonstrated that samples in M2 group with high cell density had the highest GAG content and strongest mechanical property. Statistically significant differences were observed among 3 groups. No cartilage-like tissue were formed in the 2 control groups. Conclusion Low-molecule-weight hydrogel M2 has better biocompatibility than hyaluronic acid, and M2 can be more suitable for TE cartilage construction.

Key words: Low-molecule-weight hydrogel, Cross-lincked hyaluronic acid, Injectable scaffold, Tissue engineering cartilage