Chitosan hydrogel reinforced with decellularized umbilical cord extracellular matrix and carbon nanotubes: a new trend for cartilage regeneration

Abstract

Despite many excellent properties, chitosan (CS) hydrogels are still limited in cartilage regeneration applications due to their low mechanical strength and inadequate degradation kinetics. This study seeks to surmount these limits to create a CS nanocomposite hydrogel showing better biological and physicochemical features suitable for cartilage engineering applications. To achieve this, following pepsin digestion and neutralization, plus lyophilisation, the decellularized human umbilical cord extracellular matrix (hUC-dECM) was integrated into 1.5 (w/ v) CS at two concentrations (0.4 and 0.8 w/v). This incorporation occurred either when alone or when combined with Carboxylated multi-walled carbon nanotubes (COOH-MWCNTs) at two concentrations (0.5 and 1 w/v). Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis confirmed that covalent amide cross-links successfully formed between genipin carbonyl groups (-C--C) and CS or ECM amino groups (-NH2) within the composite hydrogels. The storage modulus, loss modulus, and porosity of CS hydrogels, along with the swelling ratio, significantly increased by adding hUC-dECM and COOH-MWCNTs, while biodegradability considerably decreased due to COOH-MWCNTs presence. In vitro biocompatibility analyses of hUC-dECM and COOH-MWCNTs improved human chondrocyte adhesion and maintained their spherical morphology, which is necessary for an effective chondrogenic function and cartilage regeneration. Overall, the CS-ECM2-CNT1 nanocomposite hydrogel shows great promise as an excellent biomaterial for cartilage regeneration.