Chitosan and Hyaluronic Acid-based Double Crosslinked Hydrogels for Stem Cell Delivery and Cartilage Regeneration

Abstract

Osteoarthritis of the knee (KOA) is a degenerative disease that is increasingly occurring in the elderly population as they age. The poor proliferation rate of chondrocytes impairs cartilage recovery, and traditional treatments, including surgery, mainly focus on pain relief. The development of hydrogel-based cellular therapy offers the possibility for treatment by delivering healthy chondrocytes or stem cells to cartilage. Chitosan (CS) and hyaluronic acid (HA) are natural polysaccharides that exhibit great potential in hydrogel fabrication. The primary goal of this project is to develop and evaluate the chitosan and hyaluronic acid-based double crosslinked hydrogels for stem cell delivery. In this work, hydroxybutyl chitosan (HBCS) or catechol-hydroxybutyl chitosan (DOPA-HBCS) was mixed with aldehyde hyaluronic acid (Ald-HA) to form hydrogels via Schiff base reaction, and the thermosensitivity of HBCS and DOPA-HBCS can enhance the mechanical properties of the hydrogels. Moreover, CaCl2 was used to suppress the electrostatic interactions between CS and HA to improve the homogeneity of hydrogels. We systematically characterized the mechanical properties, degradability, swelling ratio and morphology of the HBCS/Ald-HA hydrogels. The mesenchymal stem cells (MSCs) were chosen to test the ability of encapsulation and biocompatibility of hydrogels. The hydrogel with a concentration of 10 mg/mL showed proper mechanical properties suitable for cartilage regeneration, and in vitro cell experiments showed that both HBCS/Ald-HA and DOPA-HBCS/Ald-HA hydrogels had excellent biocompatibility. High cell viability was observed when cells were encapsulated in the gels, and they continued to proliferate after release through hydrogel degradation. In addition, the presence of catechol groups increased the tissue adhesion ability of hydrogels. In brief, the HBCS/Ald-HA hydrogels exhibit excellent thermosensitivity, injectability, mechanical properties and biocompatibility. In addition to these, DOPA-HBCS/Ald-HA hydrogels showed stronger tissue adhesion ability.