Thermosensitive Chitosans as Novel Injectable Biomaterials

Abstract Two kinds of water soluble thermosensitive chitosan copolymers were prepared by graft polymerization of N ‐isopropylacrylamide (NIPAAm) onto chitosan using cerium ammonium nitrate (CAN) as an initiator (chitosan‐g‐NIPAAm) and by coupling monocarboxy Pluronic ® with chitosan using 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC) and N ‐hydroxysuccin‐imide (NHS) as coupling agents (chitosan‐Pluronic ® ). The physicochemical properties of the resulting copolymers were characterized and they formed thermally reversible hydrogel, which exhibits a lower critical solution temperature (LCST) at 34°C in aqueous solutions. The human mesenchymal stem cells (hMSCs) were cultured in the chiotsan‐g‐NIPAAm in vitro . Chondrogenic differentiation was induced in the chitosan‐g‐NIPAAm gel. Therefore, chondrogenic differentiated cells from MSCs with a thermo‐sensitive chitosan‐g‐NIPAAm could be used as an injectable cell‐polymer complex. In summary, chitosan‐g‐NIPAAm and chitosan‐Pluronic ® attest to their usefulness as injectable materials because of their thermally reversible property and relatively good biocompatibility.