Exploring Mechanotransduction and Inflammation in Human Cartilaginous Endplate Cells in Blended Collagen-Agarose Hydrogels Under Cyclic Compression.

Little is known about cartilaginous endplate (CEP) mechanobiology or how it changes in a catabolic microenvironment, partly due to difficulties in conducting mechanotransduction in vitro. Recent studies have found blended collagen-agarose hydrogels to offer improved mechanotransduction in chondrocytes compared to agarose alone. It was hypothesized that blended collagen-agarose hydrogels would be sufficient to improve the mechanobiological response in CEP cells relative to that in agarose alone, while maintaining the chondrocyte phenotype and ability to respond to pro-inflammatory stimulation. Thus, human CEP cells were seeded into blended 2% agarose and 2 mg/mL type I collagen hydrogels, followed by culture with dynamic compression up to 7% and stimulation with TNF. Results confirmed CEP cells retained a rounded phenotype and high cell viability during culture in blended collagen-agarose hydrogels. Additionally, TNF induced a catabolic response through downregulation of pericellular marker COL6A1 and anabolic markers ACAN and COL2A1. No significant changes were seen due to dynamic compression, suggesting addition of collagen to agarose was not sufficient to induce mechanotransduction in human CEP cells in this study. However, blended collagen-agarose hydrogels increased stiffness by 4× and gene expression of key cartilage marker SOX9 and physioosmotic mechanosensor TRPV4, offering an improvement on agarose alone.