Tailoring extracellular matrix niches: Impact of glycosaminoglycan content on multiple differentiation of human mesenchymal stem cells

Abstract

Glycosaminoglycan (GAG) represents an important extracellular matrix (ECM), particularly in GAG-rich tissues such as nucleus pulposus and cartilage. The ratio of GAGs/hydroxyproline (HYP) is an indicator of the relative abundance of the space-filling GAG matrix to the fibrous collagen matrix in a particular tissue. Here, we hypothesize that ECM niche with different GAG/HYP ratios will affect the outcomes of multiple differentiation of human mesenchymal stem cells (hMSCs). Specifically, we fabricated collagen-based biomaterials with different GAG/HYP ratios, and differentiate hMSCs in these materials towards osteogenic, chondrogenic and discogenic lineages. In osteogenic differentiation, Collagen without GAG (GAG/HYP ratio 0) showed higher calcium (Ca) and phosphorus (P) deposition and Ca/P ratio, more biomimetic ultrastructure, and better osteogenic phenotypic expression. For chondrogenic differentiation, aminated collagen (aCol-GAG) with intermediate GAG content (GAG/HYP ratio 5.0:1) showed higher GAG deposition, more biomimetic ultrastructure, and better chondrogenic phenotype. In discogenic differentiation, aminated collagen-aminated hyaluronic acid (aHA)-GAG (aCol-aHA-GAG) with the highest GAG content (GAG/HYP ratio 19.8:1), showed intensive GAG deposition, biomimetic ultrastructure, and higher phenotypic marker expression. This study contributes to developing collagen-based biomimetic materials with different GAG/HYP ratios and suggests the use of tissue-specific GAG/HYP ratio as a scaffold design parameter for hMSCs-based musculoskeletal tissue engineering. (198 words).