Folic acid contributes to peripheral nerve injury repair by promoting Schwann cell proliferation, migration, and secretion of nerve growth factor

After peripheral nerve injury, intraperitoneal injection of folic acid improves axon quantity, increases axon density and improves electromyography results. However, the mechanisms for this remain unclear. This study explored whether folic acid promotes peripheral nerve injury repair by affecting Schwann cell function. Primary Schwann cells were obtained from rats by in vitro separation and culture. Cell proliferation, assayed using the Cell Counting Kit-8 assay, was higher in cells cultured for 72 hours with 100 mg/L folic acid compared with the control group. Cell proliferation was also higher in the 50, 100, 150, and 200 mg/L folic acid groups compared with the control group after culture for 96 hours. Proliferation was markedly higher in the 100 mg/L folic acid group compared with the 50 mg/L folic acid group and the 40 ng/L nerve growth factor group. In Transwell assays, the number of migrated Schwann cells dramatically increased after culture with 100 and 150 mg/L folic acid compared with the control group. In nerve growth factor enzyme-linked immunosorbent assays, treatment of Schwa nn cell cultures with 50, 100, and 150 mg/L folic acid increased levels of nerve growth factor in the culture medium compared with the control group at 3 days. The nerve growth factor concentration of Schwann cell cultures treated with 100 mg/L folic acid group was remarkably higher than that in the 50 and 150 mg/L folic acid groups at 3 days. Nerve growth factor concentration in the 10, 50, and 100 mg/L folic acid groups was higher than that in the control group at 7 days. The nerve growth factor concentration in the 50 mg/L folic acid group was remarkably higher than that in the 10 and 100 mg/L folic acid groups at 7 days. In vivo, 80 μg/kg folic acid was intraperitoneally administrated for 7 consecutive days after sciatic nerve injury. Immunohistochemical staining showed that the number of Schwann cells in the folic acid group was greater than that in the control group. We suggest that folic acid may play a role in improving the repair of peripheral nerve injury by promoting the proliferation and migration of Schwann cells and the secretion of nerve growth factors.

A double-network hydrogel for the dynamic compression of the lumbar nerve root

Current animal models of nerve root compression due to lumbar disc herniation only assess the mechanical compression of nerve roots and the inflammatory response. Moreover, the pressure applied in these models is static, meaning that the nerve root cannot be dynamically compressed. This is very different from the pathogenesis of lumbar disc herniation. In this study, a chitosan/polyacrylamide double-network hydrogel was prepared by a simple two-step method. The swelling ratio of the double-network hydrogel increased with prolonged time, reaching 140. The compressive strength and compressive modulus of the hydrogel reached 53.6 and 0.34 MPa, respectively. Scanning electron microscopy revealed the hydrogel's crosslinked structure with many interconnecting pores. An MTT assay demonstrated that the number of viable cells in contact with the hydrogel extracts did not significantly change relative to the control surface. Thus, the hydrogel had good biocompatibility. Finally, the double-network hydrogel was used to compress the L4 nerve root of male sand rats to simulate lumbar disc herniation nerve root compression. The hydrogel remained in its original position after compression, and swelled with increasing time. Edema appeared around the nerve root and disappeared 3 weeks after operation. This chitosan/polyacrylamide double-network hydrogel has potential as a new implant material for animal models of lumbar nerve root compression. All animal experiments were approved by the Animal Ethics Committee of Neurosurgical Institute of Beijing, Capital Medical University, China(approval No. 201601006) on July 29, 2016.

Influence of volar margin of the lunate fossa fragment fixation on distal radius fracture outcomes:A retrospective series

BACKGROUND Distal radius fractures accompanied by the volar margin of the lunate fossa(VMLF)lesions are often overlooked or inadequately reduced in clinical practice.AIM To investigate the impact of VMLF fragment in distal radius fractures on the stability and function of the wrist joint.METHODS This was a retrospective study of patients with distal radius fractures who underwent surgical treatment between January 2013 and December 2017.The patients were divided into two groups according to whether the VMLF fragments were fixed or not.X-rays and computed tomography were performed before surgery,immediately postoperatively,and at 1,3,and 6 mo to measure the scapholunate angle,radiolunate angle,capitolunate angle,and effective radiolunate flexion(ERLF).The Mayo wrist score and disabilities of the arm,shoulder,and hand(DASH)score were determined at 1 year.RESULTS Thirty-five patients were included.There were 15 males and 20 females.Their mean age was 52.5±14.3(range:19-70)years.There were 38 wrists(17 on the left side,15 on the right,and three bilateral;16 in the fixed group,and 22 in the unfixed group).The interval between trauma and surgery was from 1 h to 1 mo.The incidence of postoperative wrist instability in the unfixed group(86.4%)was higher than in the fixed group(25.0%)(P≤0.001).Ten patients had ERLF>25°in the unfixed group and none in the fixed group(P=0.019).The Mayo wrist score was 94±5.7 in the fixed group and 68±15.1 in the unfixed group(P<0.001).The DASH score was 4.6±2.5 in the fixed group and 28.5±19.5 in the unfixed group(P<0.001).CONCLUSION Injuries of VMLF,even small fractures,might damage the radial-lunar ligament,leading to postoperative wrist instability,sagittal force line imbalance,and poor recovery of wrist joint function.