Potential of corn husk fibers reinforced chitosan-based hydrogels in cartilage tissue engineering scaffold

BACKGROUND: How to enhance the mechanical properties of the chitosan-based hydrogels has become a focus in the field of cartilage tissue engineering. In our previous research, chitosan was modified by citric acid, which led to significant improvement in the tensile and compression strength of the modified hydrogen in wet state. OBJECTIVE: To further enhance the mechanical performance of the citric acid modified chitosan hydrogel (i. e., CC) using the cellulose fibers derived from the natural corn husk fibers (CHFs), and to explore the potential of CHFs/CC composite hydrogel for cartilage tissue engineering scaffold. METHODS: A freeze-thawing method was employed to prepare CC and CHFs/CC (mass ratios of cellulose fiber to citric acid modified chitosan: 1:1 and 2:1). The structure and mechanical properties of the prepared hydrogels were characterized. Rabbit chondrocytes were seeded onto the hydrogel surface, and the cytocompatibility of the prepared hydrogels was analyzed by live/dead cell staining, CCK-8 assay, and scanning electron microscopy. The ability of CHFs/CC composite hydrogels in promoting functional expression of chondrocytes was determined by collagen immunofluorescence staining and quantitative analysis of glycosaminoglycans. RESULTS AND CONCLUSION: (1) With the increase in CHFs loading fractions, the porosity, equilibrium swelling rate, and degradation rate of CHFs/CC composite hydrogels were gradually reduced, but the compressive strength and Young's modulus in dry and wet states were significantly enhanced. (2) Live/dead cell staining revealed that at 7 days of culture, chondrocytes proliferated well on the surface of three types of hydrogels. (3) The CCK-8 assay showed that with the increase in CHF loading fractions, the proliferative ability of chondrocytes on CC was gradually decreased. (4) Scanning electron microscope revealed that the chondrocytes on CC remained elliptic and were sparsely distributed, whereas most of the chondrocytes on CHFs/CC showed completely spread morphology. (5) After 28 days of culture, with the increase of CHFs loading fractions within CC, the chondrocytes showed gradually decreased expression of type I collagen, gradually increased expression of type II collagen, and there was no significant change in the content of glycosaminoglycans secreted. (6) These results demonstrate a great potential of the CHFs/CC composite hydrogels with good mechanical strength for cartilage tissue engineering scaffold.