Neurotrophic factors such as the glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) promote nerve cell survival and regeneration, but their efficacy in repairing a longer gap defect of rat sciatic nerve (15 mm) has not been established. In this study, two recombinant mammalian vectors containing either rat GDNF gene or BDNF gene were constructed and each was transfected into neural stem cells (NSCs). It was found that the transfection of GDNF or BDNF gene into NSCs led to significantly enhanced expression of GDNF or BDNF mRNA. The amount of GDNF or BDNF protein secreted from the transfected NSCs showed a 3.3-fold or 2.5-fold increase than that from nontransfected NSCs, respectively. The regeneration capacity of rat sciatic nerve in a poly(D,L-lactide) conduit seeded with GDNF or BDNF-transfected NSCs was evaluated by the histology, functional gait, and electrophysiology after 8 weeks of implantation. It was observed that the degree of myelination and the size of regenerated tissue in the conduits seeded with GDNF- and BDNF-transfected NSCs were higher than those seeded with the nontransfected NSCs. Conduits seeded with GDNF-transfected NSCs had the greatest number of blood vessels. The functional recovery assessed by the functional gait and electrophysiology was significantly improved for conduits seeded with GDNF or BDNF-transfected NSCs. It was concluded that the genetically modified NSCs may have potential applications in promoting nerve regeneration and functional recovery.

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Platelet-rich plasma (PRP) is a kind of plasma that is rich in platelets after processing. It includes various growth factors and cytokines, which speed up the process of wound healing and hemostasis. The PRP solution used in this study is diluted from lyophilized PRP powder, which decreased the possibility of contamination, facilitated the storage, and prolonged the storage life. From in vitro fibroblast proliferation testing, the numbers of PRP supplement were performed for 1, 4, and 7 times by continuous replacement of culture medium each day. Four times of lyophilized PRP supplement was selected for clinical study due to sufficient promotion of fibroblast proliferation. Next, 27 patients of deep second-degree burn wound were included in this study. Patients were assigned to two groups: PRP group (n = 15) and control group (n = 12). A concentration of 1.0 × 10 platelets/cm (wound area) according to wound size was sprayed on the wound evenly. Function was mainly assessed by the percentage of wound closure and bacteria picking out rate in 2 and 3 weeks. The wound closure at 3 weeks showed a significant difference in PRP group (P < 0.05). The healing rate of PRP group reached nearly 80% and made a breakthrough of 90% in 3 weeks, showing a significant difference compared with the control group (P < 0.05). Lyophilized PRP can be considered as an effective treatment to increase healing rate in patients with deep second-degree burn injury.