The co-influence of hyaluronic acid and collagen on the development of an engineered annulus tissue model with bone marrow stromal cells.

Inveterbral disc degeneration is a significant musculoskeletal disease that brings huge burden of pain, disability, psychological and social consequences to the affected population worldwide with treatments that only alleviate the pain but does not address the underlying biological problems. For the past decades, tissue engineering of the disc has been investigated with annulus fibrosus (AF) been one of the complicated disc component to be engineered. With the limited source of annulus cells, bone marrow stromal cells (BMSCs) have been frequently investigated as a potental cell candidate to develop an AF-like tissue which often require a multi-disciplinary effort to achieve. The extracellular matrix of AF is largely make up of collagen and proteoglycan which is still unclear how these matrix proteins could influence the BMSCs towards constructing a AF-like tissue. In this study, we adopted a coiled hydrogel microfiber that resembles the micro-architecture of the native AF tissue to encapsulate BMSCs and incorporated collagen type 1 and hyaluronic acid which later demonstrated that the co-presence of hyaluronic acid and collagen could potentially regulated AF-associated biomarkers and protease expression which are critical for later development of an engineered AF tissue construct.