Recombinant human epidermal growth factor combined with vacuum sealing drainage for wound healing in Bama pigs

Background:Vacuum sealing drainage(VSD)and epidermal growth factor(EGF)both play an important role in the treatment of wounds.This study aims to explore the effects of the combination of VSD and EGF on wound healing and the optimal concentration and time of EGF.Methods:We tested the proliferation and migration capacity of HaCaT and L929 cells at different EGF concentrations(0,1,5,10,and 100ng/ml)and different EGF action times(2,10,and 30min).A full-thickness skin defect model was established using male,30-week-old Bama pigs.The experiment included groups as follows:routine dressing change after covering with sterile auxiliary material(Control),continuous negative pressure drainage of the wound(VSD),continuous negative pressure drainage of the wound and injection of EGF 10min followed by removal by continuous lavage(V+E 10min),and continuous negative pressure drainage of the wound and injection of EGF 30min followed by removal by continuous lavage(V+E 30min).The wound healing rate,histological repair effect and collagen deposition were compared among the four groups.Results:An EGF concentration of 10ng/ml and an action time of 10min had optimal effects on the proliferation and migration capacities of HaCaT and L929 cells.The drug dispersion effect was better than drug infusion after bolus injection effect,and the contact surface was wider.Compared with other groups,the V+E 10min group promoted wound healing to the greatest extent and obtained the best histological score.Conclusions:A recombinant human epidermal growth factor(rhEGF)concentration of 10 ng/ml can promote the proliferation and migration of epithelial cells and fibroblasts to the greatest extent in vitro.VSD combined with rhEGF kept in place for 10min and then washed,can promote wound healing better than the other treatments in vitro.

Extracellular matrix from human umbilical cordderived mesenchymal stem cells as a scaffold for peripheral nerve regeneration

The extracellular matrix,which includes collagens,laminin,or fibronectin,plays an important role in peripheral nerve regeneration.Recently,a Schwann cell-derived extracellular matrix with classical biomaterial was used to mimic the neural niche.However,extensive clinical use of Schwann cells remains limited because of the limited origin,loss of an autologous nerve,and extended in vitro culture times.In the present study,human umbilical cord-derived mesenchymal stem cells（h UCMSCs）,which are easily accessible and more proliferative than Schwann cells,were used to prepare an extracellular matrix.We identified the morphology and function of h UCMSCs and investigated their effect on peripheral nerve regeneration.Compared with a non-coated dish tissue culture,the h UCMSC-derived extracellular matrix enhanced Schwann cell proliferation,upregulated gene and protein expression levels of brain-derived neurotrophic factor,glial cell-derived neurotrophic factor,and vascular endothelial growth factor in Schwann cells,and enhanced neurite outgrowth from dorsal root ganglion neurons.These findings suggest that the h UCMSC-derived extracellular matrix promotes peripheral nerve repair and can be used as a basis for the rational design of engineered neural niches.

Aligned fibers enhance nerve guide conduits when bridging peripheral nerve defects focused on early repair stage

Nerve conduits enhance nerve regeneration in the repair of long-distance peripheral nerve defects. To help optimize the effectiveness of nerve conduits for nerve repair, we developed a multi-step electrospinning process for constructing nerve guide conduits with aligned nanofibers. The alignment of the nerve guide conduits was characterized by scanning electron microscopy and fast Fourier transform. The mechanical performance of the nerve guide conduits was assessed by testing for tensile strength and compression resistance. The biological performance of the aligned fibers was examined using Schwann cells, PC12 cells and dorsal root ganglia in vitro. Immunohistochemistry was performed for the Schwann cell marker S100 and for the neurofilament protein NF200 in PC12 cells and dorsal root ganglia. In the in vivo experiment, a 1.5-cm defect model of the right sciatic nerve in adult female Sprague-Dawley rats was produced and bridged with an aligned nerve guide conduit. Hematoxylin-eosin staining and immunohistochemistry were used to observe the expression of ATF3 and cleaved caspase-3 in the regenerating matrix. The recovery of motor function was evaluated using the static sciatic nerve index. The number of myelinated fibers, axon diameter, fiber diameter, and myelin thickness in the distal nerve were observed by electron microscopy. Gastrocnemius muscle mass ratio was also determined. The analyses revealed that aligned nanofiber nerve guide conduits have good mechanical properties and can induce Schwann cells, PC12 cells and dorsal root ganglia to aggregate along the length of the nanofibers, and promote the growth of longer axons in the latter two(neuronal) cell types. The aligned fiber nerve conduits increased the expression of ATF3 and cleaved caspase-3 at the middle of the regenerative matrix and at the distal nerve segment, improved sciatic nerve function, increased muscle mass of the gastrocnemius muscle, and enhanced recovery of distal nerve ultrastructure. Collectively, the results show that highly aligned nanofibers improve the performance of the nerve conduit bridge, and enhance its effectiveness in repairing peripheral nerve defects.

Bioinformatic analysis of cytokine expression in the proximal and distal nerve stumps after peripheral nerve injury

In our previous study,we investigated the dynamic expression of cytokines in the distal nerve stumps after peripheral nerve injury using microarray analysis,which can characterize the dynamic expression of proteins.In the present study,we used a rat model of right sciatic nerve transection to examine changes in the expression of cytokines at 1,7,14 and 28 days after injury using protein microarray analysis.Interleukins were increased in the distal nerve stumps at 1–14 days post nerve transection.However,growth factors and growth factor-related proteins were mainly upregulated in the proximal nerve stumps.The P-values of the inflammatory response,apoptotic response and cell-cell adhesion in the distal stumps were higher than those in the proximal nerve stumps,but the opposite was observed for angiogenesis.The number of cytokines related to axons in the distal stumps was greater than that in the proximal stumps,while the percentage of cytokines related to axons in the distal stumps was lower than that in the proximal nerve stumps.Visualization of the results revealed the specific expression patterns and differences in cytokines in and between the proximal and distal nerve stumps.Our findings offer potential therapeutic targets and should help advance the development of clinical treatments for peripheral nerve injury.Approval for animal use in this study was obtained from the Animal Ethics Committee of the Chinese PLA General Hospital on September 7,2016(approval No.2016-x9-07).