Silicon-induced biofilm improves peripheral nerve defect in rats mediated by VEGF/VEGFR2/ERK.

Background: Injury of peripheral nerve capable of regeneration with much poorer prognosis affects people's life quality. The recovery of nerve function after transplantation for peripheral nerve injury remain a worldwide problem. Silicon-induced biofilms as vascularized biological conduits can promote nerve regeneration by encapsulating autologous or allogeneic nerve graft.Objective: We proposed to explore the effect of silicon-induced biofilms on nerves regeneration and whether the VEGF/VEGFR2/ERK pathway was involved in the present study.Methods: Biofilms around the transplanted nerves in peripheral nerve injury rats were induced by silicon. Vascularization and proteins related to VEGF/VEGFR2/ERK were measured. Pathology and morphology of nerves were investigated after encapsulating the transplanted nerves by silicon-induced biofilms.Results: Our results indicated that the biofilms induced by silicon for 6 weeks showed the most intensive vascularization and the optimal effect on nerve regeneration. Moreover, silicon-induced biofilms for 4, 6 and 8 weeks could significantly secrete VEGF with the highest content at week 6 after induction. VEGFR2, VEGF, p-VEGFR2, ERK1, ERK2, p-ERK1 and p-ERK2 were expressed in the biofilms. p-VEGFR2, p-ERK1 and p-ERK2 expression were different at each time point and significantly increased at week 6 compared with that at week 4 or week 8 which was consistent with that 6 week of was the optimum time for biofilms induction to improve the nerve repair after peripheral nerve injury.Conclusion: Our results suggested that combination of silicon-induced autologous vascularized biofilm and autologous transplantation may promote the repair of rat sciatic nerve defect quickly through VEGF/VEGFR2/ERK pathway.

Comparison of osteogenic activity from different parts of induced membrane in the Masquelet technique.

BACKGROUND: The Masquelet technique is widely used to treat long-bone segmental defects because of its high success rate and low surgical difficulty. However, the cause of the uneven growth of bone grafts following this procedure remains unclear. METHODS: Rats were randomly divided into four groups for analysis 2-, 4-, 6- and 8-weeks postoperatively and underwent a uniform surgical procedure to construct a 10 mm bone defect in the right posterior branch of the femur. Induced membrane specimens were harvested at the appropriate time points and divided into segments according to their location. Bone growth activity was assessed by immunohistochemistry, western blotting, and quantitative real-time polymerase chain reaction. RESULTS: Mature blood vessels were more densely distributed at the proximal end of the bone defect than at other locations at all time points. The number of blood vessels on the same side of the longitudinal axis of the femur also varied depending on location. The difference between the proximal-anterior and distal-anterior regions within the induced membranes was most pronounced at 6 weeks postoperatively and decreased by 8 weeks postoperatively. The differences between the proximal-posterior and distal-posterior regions within the induced membranes were more pronounced. The expression of the growth factors bone morphogenetic protein-2 (BMP-2), vascular endothelial growth factor A(VEGFA), and transforming growth factor-ß1(TGF-ß1) in the proximal-posterior regions of the bone defect was almost always higher than that in other regions at the same time point. The expression of BMP-2 in the posterior regions of the bone defect was always higher than that in the anterior regions at the same end of the femoral longitudinal axis. CONCLUSION: The number and maturation of vessels in the proximal region of the induced membrane at the bone defect site were higher than those in the distal region, and the expression of growth factors was higher, with the highest induced membrane activity in the proximal-posterior regions of the bone defect. Therefore, there was inhomogeneity in induced membrane activity.

Varying degrees of spontaneous osteogenesis of Masquelet's induced membrane: experimental and clinical observations.

BACKGROUND: Masquelet's induced membrane (IM) has osteogenesis activity, but IM spontaneous osteogenesis (SO) has not been described previously. OBJECTIVES: To report on varying degrees of IMSO and analyze its possible causes. METHODS: Twelve eight-week-old male Sprague-Dawley rats with 10 mm right femoral bone defects who received the first stage of IM technique (IMT) were used to observe the SO. In addition, clinical data from patients with bone defects who received the first stage of IMT with an interval of > 2 months post-operatively and exhibited SO between January 2012 and June 2020 were retrospectively analyzed. The SO was divided into four grades according to the amount and characteristics of the new bone formation. RESULTS: At twelve weeks, grade II SO was observed in all rats, and more new bone was formed in the IM near the bone end forming an uneven margin. Histology revealed bone and cartilage foci in the new bone. Four of the 98 patients treated with the first stage of IMT exhibited IMSO, including one female and three males with a median age of 40.5 years (range 29-52 years). The bone defects were caused by severe fractures and infection in two cases and by infection or tumor in one case each. Partial or segmental defects occurred in two cases. The time interval between inserting a cement spacer and diagnosis of SO ranged from six months to nine years. Two cases were grade I, and one case each of grades III and IV. CONCLUSION: Varying degrees of SO confirm the existence of the IMSO phenomenon. Bioactive bone tissue or local inflammation and a long time interval are the primary reasons underlying enhancement of the osteogenic activity of IM and leading to SO, which tends to take place as endochondral osteogenesis.

A novel minimally invasive broken nail extractor for cannulated intramedullary nails: Trial and application in a few cases.

Successful and minimally invasive extraction of a broken distal end of an intramedullary nail is challenging. This study introduces a simple and reproducible technique for the extraction of broken cannulated intramedullary nails using a novel minimally invasive broken nail extractor. Five amputated adult lower-leg specimens were used to create models of the broken distal end of the cannulated intramedullary nails remaining in the medullary cavity of the distal tibia. Two orthopedic resident physicians with experience in tibial intramedullary nail implantation were selected to blindly extract the broken intramedullary nail using the novel minimally invasive broken nail extractor. The extraction outcome was assessed. The broken nail extractor was applied to 3 patients with broken intramedullary nails remaining in the medullary cavity of the distal tibia. In the lower-leg specimens, the extraction success rate was 100%, the median number of extraction times was 1.9 (range 1-3.5), and the median duration of extraction was 38 s (range 20-52 s). All the broken intramedullary nails in the 3 patients were successfully extracted without complications related to the surgery. The study shows that our technique is simple, reproducible, and has a high extraction success rate, but more case applications are needed to verify its effect.