Cytocompatibility and Physical Properties of Chitosan-Based Hydrogels: Joint Lubrication Implications

Objectives: Osteoarthritis (OA) is one of the leading factors influencing the quality of life, most common in older age groups but not uncommon in younger age groups. OA can affect any joint including the Temporomandibular joint (TMJ). Various treatments of OA currently include pharmacological and non-pharmacological methods.
Methods: This research was based on a concept of intra-articular injection of a chitosan/glycerol-phosphate based hydrogel in comparison with two formulations of chitosan hydrogel containing mustard powder as a potential antioxidant. The effect of the gels on human calvarial osteoblasts (HCO; ScienCell) was evaluated by the MTT assay, which measures mitochondrial activity as an indicator of cell growth. The physical properties of the gels were also studied.
Results: Based on the MTT results, when hydrogels with and without mustard were used for the assay (24-well culture plate), no-gel control’s mitochondrial activity was greater than chitosan hydrogel groups (p<0.05). When compared with an agar gel control, chitosan hydrogels produced greater mitochondrial activity (p<0.05). Area occupied by the gel in the well, could be the reason for mitochondrial activity variation. Conditioned medium from hydrogels (48 hours) were used for additional assays, which showed no statistically significant difference in mitochondrial activity between no-gel control and the conditioned media (p>0.05). To investigate if surface area impacts cell growth, the culture well surface area was increased for the MTT assay (12-well plate, instead of 24-well plate). The 12-well results confirm area occupied by hydrogel might affect cell growth. Compression tests indicated that there was no statistically significant difference among the gels. Tissue-on-tissue coefficient of friction indicated the hydrogels can reduce friction.
Conclusions: Based on the results obtained, chitosan hydrogels with and without mustard are not cytotoxic, and since the gels can reduce friction, there is a basis for further studies of their use as a joint lubricant.