A catechol-chitosan-based adhesive and injectable hydrogel resistant to oxidation and compatible with cell therapy.

Injectable hydrogels designed for cell therapy need to be adhesive to the surrounding tissues to maximize their retention and the communication between the host and the encapsulated cells. Catechol grafting is an efficient and well-known strategy to improve the adhesive properties of various polymers, including chitosan. However, catechol groups are also known to be cytotoxic as they oxidize into quinones in alkaline environments.

Injectable Chitosan Hydrogels with Enhanced Mechanical Properties for Nucleus Pulposus Regeneration.

A thermosensitive chitosan-based hydrogel was developed, which mimics the mechanical properties of the human nucleus pulposus (NP) tissue and provides a suitable environment for seeded NP cells to live and produce glycosaminoglycans. This scaffold is injectable through 25G needle and rapidly gels at body temperature. It has the potential to restore mechanical properties and stimulate biological repair of the degenerated intervertebral disc (IVD).

An injectable chitosan/chondroitin sulfate hydrogel with tunable mechanical properties for cell therapy/tissue engineering.

Chitosan (CH) hydrogels with remarkable mechanical properties and rapid gelation rate were recently synthesized by combining sodium hydrogen carbonate (SHC) with another weak base, such as beta-glycerophosphate (BGP). To improve their biological responses, in the present study, chondroitin sulfate (CS) was added to these CH hydrogels. Hydrogel characteristics in terms of pH and osmolarity, as well as rheological, mechanical, morphological and swelling properties, were studied in the absence and presence of CS.

Optimization of Injectable Thermosensitive Scaffolds with Enhanced Mechanical Properties for Cell Therapy.

Strong injectable chitosan thermosensitive hydrogels can be created, without chemical modification, by combining sodium hydrogen carbonate with another weak base, namely, beta-glycerophosphate (BGP) or phosphate buffer (PB). Here the influence of gelling agent concentration on the mechanical properties, gelation kinetics, osmolality, swelling, and compatibility for cell encapsulation, is studied in order to find the most optimal formulations and demonstrate their potential for cell therapy and tissue engineering. The new formulations present up to a 50-fold increase of the Young's modulus after gelation compared with conventional chitosan-BGP hydrogels, while reducing the ionic strength to the level of iso-osmolality.