Synthesis of an injectable heparin conjugated poloxamer hydrogel with high elastic recoverability for temporomandibular joint disorders

The temporomandibular joint (TMJ) is commonly affected during fundamental oral activities, reducing the quality of life. Herein, we synthesized a heparin-conjugated poloxamer hydrogel (HEP) as a thermo-responsive injectable hydrogel for the treatment of TMJ disorders. While the gelation temperature of synthesized HEP (25% [w/v]) was 29.8-30.0 degrees C, there was a slight difference between loss and storage modulus. HEP decreased the friction of the TMJ, thus requires less energy during load-bearing jaw movement in comparison to POL. Moreover, the oscillation test dependent on strain ranges from 0.01% to 1000% validated that POL and HEP3 hydrogels showed a similar critical strain of about 5.6%. The total elastic recovery percentage of HEP3 (53.50%) was higher than POL (45.55%), indicating a better recovery of the deformed hydrogel structure. Along with the suitable viscoelastic properties for temporomandibular cavity, both hydrogels increased the proliferation of fibroblasts (L929) and chondrocytes (ATDC5) (cell viabilities were above 100%). However, newly synthesized HEP induced differentiated cell proliferation of chondrogenic cells at increasing concentrations up to 0.0156 mg/mL (p < 0.0001) compared to POL and the control group. The promising rheological properties and effects on chondrogenic cell proliferation of injectable heparin-conjugated hydrogel make them candidates for intra-articular injections used for the treatment of TMJ.