Biomaterials
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Previous reports in the literature investigating chondrogenesis in mesenchymal progenitor cell (MPC) cultures have confirmed the chondro-inductive potential of pentosan polysulphate (PPS), a highly sulphated semi-synthetic polysaccharide, when added as a soluble component to culture media under standard aggregate-assay conditions or to poly(ethylene glycol)/hyaluronic acid (PEG/HA)-based hydrogels, even in the absence of inductive factors (e.g. TGFβ). In this present study, we aimed to assess whether a 'bound' PPS would have greater activity and availability over a soluble PPS, as a media additive or when incorporated into PEG/HA-based hydrogels. ⋯ When encapsulated in the hydrogels, MPCs retained good viability and rapidly adopted a rounded morphology. Histological analysis of both GAG and collagen deposition after 21 days showed that the incorporation of the bound-PPS into the hydrogel resulted in increased matrix formation when compared to the addition of soluble PPS to the hydrogel, or the hydrogel alone. We believe that this new generation injectable, degradable hydrogel, incorporating now a covalently bound-PPS, when combined with MPCs, has the potential to assist cartilage regeneration in a multitude of therapeutic targets, including for intervertebral disc (IVD) degeneration.