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Peripheral nerve regeneration and functional recovery remain major challenges in clinical practice. Nerve guidance conduits (NGCs) which can regulate the regenerative microenvironment are beneficial for peripheral nerve repair. Platelet-rich plasma (PRP) can secrete multiple growth factors to regulate the regenerative microenvironment. However, current administration methods of PRP are rapidly activated followed by the burst release of growth factors, causing low therapeutic efficiency in vivo. To overcome these disadvantages, a composite nerve conduit was fabricated by incorporating PRP into a gelatin methacrylate (GelMA) and sodium alginate (SA) hydrogel. The GelMA/SA-3/PRP-20 NGCs possess optimal mechanical properties, degradation rate, and superior biological performance. Importantly, GelMA/ SA-3/PRP-20 NGCs achieved the sustained release of two major growth factors (VEGF-A, PDGF-BB) from PRP. Moreover, the GelMA/SA-3/PRP-20 NGCs significantly promoted the migration of Schwann cells and the neovascularization of endothelial cells in vitro. While bridging 10 mm rat sciatic nerve defects, the GelMA/SA-3/PRP-20 NGCs promoted axonal regeneration and functional recovery of peripheral nerves. Therefore, the GelMA/SA-3/PRP-20 NGCs could regulate the regenerative microenvironment by sustained release of growth factors from PRP and shed new light on the clinical application of PRP in peripheral nerve repair.

Objective: To evaluate the growth of olfactory ensheathing cells (OECs) on the silk fibroin (SF) nanofibers scaffold. Methods: The purified OECs were cultured with poly-L-lysine (control group) and 1200 nm SF nanofibers (experimental group). The morphological features and growth characteristics of which were analyzed by phase contrast microscopy. Nerve growth factor receptor (NGFR) p75 were applied to identify OECs by immunostaining. SEM was used to observe the adherence and spreading of OECs on different substrates. MTT assay was performed to evaluate the proliferation activity of OECs both on the control and experimental scaffolds. Results: The isolated OECs reached confluence after 4-5 days of culture, which were stained for antibody NGFRp75(+). The morphology of OECs on the 1200 nm SF nanofibers was similar to that on the control group. The SEM clearly revealed the close interaction between the OECs and the nanofbers. The OECs on SF nanofibers still maintain its original characteristic phenotypes. The MTT showed that the most obvious proliferation was reached over 10 days. The differences of OD values between 1200 nm SF and PLL were significant at day 5, 7 (p < 0.05). However, there was no significant difference at day 10. Conclusion: SF nanofibers scaffold could support the growth of OECs, and may be a promising tissue-engineered scaffold for the repair of SCI.