Ultrasound-guided platelet-rich plasma injection and multimodality ultrasound examination of peripheral nerve crush injury

Ultrasound-guided platelet-rich plasma (PRP) injection is able to make up for the limitations of applying a single growth factor. The goal of this study was to investigate the effects of serial ultrasound-guided PRP injections of the appropriate concentration on the treatment of sciatic nerve crush injury, and explore the value of multimodality ultrasound techniques in evaluating the prognosis of crushed peripheral nerve. In vitro, optimal concentration of PRP (from 150%, 250%, 450%, and 650%) was screened due for its maximal effect on proliferation and neurotrophic function of Schwann cells (SCs). In vivo, ninety rabbits were equally and randomly divided into normal control, model, PRP-2.5x, PRP-4.5x, and PRP-6.5x groups. The neurological function and electrophysiological recovery evaluation, and the comparison of the multimodality ultrasound evaluation with the histological results of sciatic nerve crush injury were performed to investigate the regenerative effects of PRP at different concentrations on the sciatic nerve crush injury. Our results showed that the PRP with a 4.5-fold concentration of whole blood platelets could significantly stimulate the proliferation and secretion of SCs and nerve repair. The changes in stiffness and blood perfusion were positively correlated with the collagen area percentage and VEGF expression in the injured nerve, respectively. Thus, serial ultrasound-guided PRP injections at an appropriate concentration accelerates the recovery of axonal function. Multimodality ultrasound techniques provide a clinical reference for prognosis by allowing the stiffness and microcirculation perfusion of crush-injured peripheral nerves to be quantitatively evaluated.