Regeneration of sciatic nerve crush injury by a hydroxyapatite nanoparticle-containing collagen type I hydrogel.

The current study aimed to enhance the efficacy of peripheral nerve regeneration using a hydroxyapatite nanoparticle-containing collagen type I hydrogel. A solution of type I collagen, extracted from the rat tails, was incorporated with hydroxyapatite nanoparticles (with the average diameter of ~212 nm) and crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) to prepare the hydrogel. The Schwann cell cultivation on the prepared hydrogel demonstrated a significantly higher cell proliferation than the tissue culture plate, as positive control, after 48 h (n = 3, P < 0.005) and 72 h (n = 3, P < 0.01). For in vivo evaluation, the prepared hydrogel was administrated on the sciatic nerve crush injury in Wistar rats. Four groups were studied: negative control (with injury but without interventions), positive control (without injury), collagen hydrogel and hydroxyapatite nanoparticle-containing collagen hydrogel. After 12 weeks, the administration of hydroxyapatite nanoparticle-containing collagen significantly (n = 4, P < 0.005) enhanced the functional behavior of the rats compared with the collagen hydrogel and negative control groups as evidenced by the sciatic functional index, hot plate latency and compound muscle action potential amplitude measurements. The overall results demonstrated the applicability of the produced hydrogel for the regeneration of peripheral nerve injuries.