Object ive To summa r i z e the advanc ement of cytoske l e ton and axon outgrowth of neuron. Methods The recent l iterature concerning cytoskeleton and axon outgrowth of neuron was reviewed and summarized. Results The actin filaments and microtubules in neuron were highly polarized and dynamic structures confined to the ti ps of axons and the reci procal interactions between these two major cytoskeletal polymers was also dynamic. Attractive or a repulsive cue whose final common path of action was the growth cone cytoskeleton mediated the growth of axons of neuron by intracellular signaling cascades. Regulating the actin filament and microtubule dynamics as well as their interactions in growth cones played a key role in neurite outgrowth and axon guidance. Rho-GTPases and glycogen synthase kinase 3β (GSK-3β), the two major intracellular signal ing pathways had emerged in recent years as candidates for regulating the dynamics of actin filaments and microtubules. Conclusion The axon outgrowth and guidance depend on well-coordinated cytoskeletal and reciprocal interaction dynamics which also mediate axon regeneration after spinal cord injury. Regulating activity of Rho-GTPases and GSK- 3β simultaneously may acts as key role to regulate the dynamics of cytoskeletal and to determine axon outgrowth.
Objective To investigate a new composite matrix (BMSCs seeded on the denuded human amniotic membrane, BMSCs-DHAM) bridging the both stumps of spinal cord injury in rats to promote axon regeneration and improve motor function of hind l imbs. Methods The human amniotic membrane (HAM) was voluntarily donated by the healthy pregnant women after a caesarean section. The cells on the HAM were completely removed with a tryptic and mechanical approach to prepare DHAM. The BMSCs were separated and cultured from 4-week-old female rats (n=4), then the forth passage of BMSCs were labeled by PKH26 and seeded on DHAM (BMSCs-DHAM). The growing state of BMSCs was observed under themicroscopy. Moreover, 40 female rats (8-week-old, weighting 200-220 g) were made spinal cord injury models by transecting at T9 level, and were randomly divided into 4 groups (each group, n=10). The both stumps were respectively wrapped by BMSCs- DHAM or simple DHAM in groups A and C, and the same dose of BMSCs or physiological sal ine were also respectively injected the central lesion in groups B and D. At 12 weeks after surgery, the functional recovery of the hindl imbs was evaluated by the BBB locomotor rating score, and other indexes were tested including cortical motion evoked potential (MEP), anterograde biopinylated dextan amine (BDA) tracing, and immunofluorescence of neurofilament protein 200 (NF-200). Results HE staining proved that the DHAM was devoid of cellular components by this way, and BMSCs grew well on the substrate under the microscopy. At 12 weeks after operation, the BBB score (12.50 ± 1.26) in group A was significantly higher than those of other groups (P lt; 0.05), and the recovery in latency (3.52 ± 2.45) ms and ampl itude (480.68 ± 18.41) μV of MEP was also obviously improved in group A (P lt; 0.05) when compared with other groups. In addition, anterograde BDA tracing revealed that the rate of the positive BDA axons 54.12% ± 3.30% under the lesion level in group A was higher than those of other groups (P lt; 0.05), and lots of the regeneration axons (positive NF-200) were found to grow into the spinal cord under the composite matrix in group A. Conclusion The BMSCs-DHAM composite matrix can improve hindl imb motor function to some extent after spinal cord injury. It will be widely appl ied as the matrix material in the future.
The optic nerve belongs to the central nervous system (CNS). Because of the lack of neurotrophic factors in the microenvironment of the CNS and the presence of myelin and glial scar-related inhibitory molecules, and the inherent low renewal potentials of CNS neurons comparing to the peripheral nerve system, it is difficult to spontaneously regenerate the optic nerve after injury. Protecting damaged retinal ganglion cells (RGCs), supplementing neurotrophic factor, antagonizing axon regeneration inhibitory factor, and regulating the inherent regeneration potential of RGCs can effectively promote the regeneration and repair of optic nerve. Basic research has made important progress, including the restoration of visual function, but there are still a lot of unsolved problems in clinical translation of these achievements, so far there is no ideal method of treatment of optic nerve injury. Therefore, it is rather urgent to strengthen the cooperation between basic and clinical research, to promote the transformation of basic research to the clinical applications as soon as possible, which will change the unsatisfactory clinical application status.
The purpose of this experiment was to elucidate the influence of the low-energy He-Ne laser on the function of regeneration of peripheral nerve. Forty-four rabbits about 2.5 kg body weight were used in the experiment. The animals were divided into 4, 8, 12, 16 weeks groups according to the observation period. Six animals were used in each irradiated group and in the control group 5 rabbits were used in each observation period. Regeneration of the axon and myelinc sheath, the latent rate of the common peroneal nerve, the conditions of the anterior tibital muscle and the toe expansion test were all observed systematically in both groups. The experimental results was: A few thin regenerated axon was seen at 4 weeks in the irradiated group, while in the control group it might be seen at 8 weeks, the P value was lt; 0.01. A low amplitude latent rate of the common peroneal nerve is determined at the peroneal side of the anterior tibial muscle in a few animal at 4 weeks of the irradiated group, and it is not observed in the control group, from 12 to 16 weeks. THe latent rate of the common peroneal nerve was the irradiated group than in the controlled, the P value was lt; 0.01. The regeneration of the myeline sheath was evident in the irradiated group, and also the slstion of the musdle fibers anterior tibial muscle was clearly visible than the controlled. 16 weeks postoperatively, the toe expansion test was normal in the irradiated group, while in the control group it was the same as seen at 12 weeks after operation in the irradiated group. Now it was certain that the low-energy He-Ne laser could promole the function of the spinal motor nerve cells and accelerate the axonal regeneration.
ObjectiveTo observe the effect of G protein alpha inhibitory subunit (Gαi) 1 and Gαi3 on signal transduction and angiogenesis induced by Netrin-1 (NTN1) and explore the possible mechanisms. MethodsTwenty male C57BL/6J mice aged 6 to 8 weeks were randomly assigned to a control group and a diabetic group, with 10 mice in each group. Diabete group mice were induced by streptozotocin to establish diabetes model. 12 weeks after modeling, quantitative real-time polymerase chain reaction and Western blot were performed to detect the expression of Ntn1, Gαi1 and Gαi3 in diabetic retinas. Additionally, 35 male C57BL/6J mice aged 2 weeks were randomly stratified into three groups: a control group, an intravitreal injection of NTN1 group (NTN1 group), and a retinal endothelial cell-specific Gαi1/Gαi3 knockdown coupled with intravitreal NTN1 injection group (Gαi1/Gαi3 eKD+NTN1 group), with 15 mice in each of the normal control and NTN1 groups, and 5 mice in the Gαi1/Gαi3 eKD+NTN1 group. Isolectin B4 staining was performed to observe retinal neovascularization. In vitro, human umbilical vein endothelial cells (HUVEC) were divided into four groups: negative control lentiviral transfection group (shC group), negative control lentiviral transfection+NTN1 treatment group (shC+NTN1 group), Gαi1/Gαi3 knockdown group (shGαi1/Gαi3 group), and Gαi1/Gαi3 knockdown+NTN1 treatment group (shGαi1/Gαi3+NTN1 group). The effects of NTN1, Gαi1, and Gαi3 on HUVEC proliferation were assessed using the EdU assay. Transwell assays were conducted to determine the effects on HUVEC migration, and Matrigel assays were used to evaluate the effects on HUVEC tube formation. Protein kinase B (Akt), phosphorylated Akt (p-Akt), ribosomal protein S6 kinase (S6K), phosphorylated S6K (p-S6K), extracellular regulatory protein kinase (Erk1/2), phosphorylated Erk1/2 (p-Erk1/2) protein expression on HUVEC were detected by Western blot. ResultsCompared with the control group, the relative expression levels of Ntn1, Gαi1, and Gαi3 mRNA and protein in the diabetic group retina were significantly increased, with statistically significant differences (t=11.800, 9.298, 10.620, 7.503, 3.432, 8.037; P＜0.000 1). Compared with the shC group, the relative expression levels of Gαi1 and Gαi3 mRNA and protein in the shGαi1/Gαi3 group in HUVEC were significantly reduced, showing statistically significant differences (t=16.310, 16.300, 13.600, 9.068; P＜0.000 1). HUVEC proliferation rate, migration number and lumen formation number: compared with shC group, shC+NTN1 group significantly increased, while shGαi1/Gαi3 group and shGαi1/Gαi3+NTN1 group significantly decreased, and the differences were statistically significant (F=62.750, 49.830, 54.900; P＜0.000 1). Compared with the control group, the relative expression levels of Gαi1 and Gαi3 mRNA and protein in retina were significantly decreased in the Gαi1/Gαi3 eKD group, showing statistically significant differences (t=10.920, 13.460, 9.219, 10.500; P＜0.000 1). Retinal neovasculogenesis area: compared with the normal control group, the area of retinal neovasculogenesis increased significantly in the NTN1 group, but decreased significantly in the Gαi1/Gαi3 eKD+NTN1 group, with statistical significance (F=24.010, P＜0.000 1). The protein expression of p-Akt relative to Akt, p-S6K relative to S6K, and p-Erk1/2 relative to Erk1/2: compared with shC group, the protein expression of shC+NTN1 group was significantly increased, while that of shGαi1/Gαi3 group and shGαi1/Gαi3+NTN1 group was significantly decreased, with statistical significance (F=78.610, 144.400, 77.010; P＜0.000 1). ConclusionsNTN1 induces Gαi1/Gαi3 to mediate activation of downstream Akt-mammalian target proteins of rapamycin and Erk1/2, thereby promoting angiogenesis in vivo and in vitro environments. Knocking down Gαi1/Gαi3 significantly reduces the NTN1-induced angiogenesis effect.
Primary or secondary death of retinal ganglion cells (RGC) is a common outcome in various optic neuropathies, often resulting in severe visual damage. The inherent characteristics of RGC include the continuous upregulation of intracellular growth-inhibitory transcription factors and the downregulation of growth-inducing transcription factors during cell differentiation. Additionally, the external inhibitory microenvironment following RGC damage, including oxidative stress, chronic inflammation, lack of neurotrophic factors, high expression of myelin proteins, and the formation of glial scars, all restrict axonal regeneration. Both intrinsic and extrinsic factors lead to the death of damaged RGC and hinder axonal regeneration. Various neuroprotective agents and methods attempt to promote neuroprotection and axonal regeneration from both intrinsic and extrinsic aspects, and well knowledge of these neuroprotective strategies is of significant importance for promoting the neuroprotective experimental research and facilitating its translation into clinical practice.
The ‘glial scar’ has been widely studied in the regeneration of spinal cord injury (SCI). For decades, mainstream scientific concept considers glial scar as a ‘physical barrier’ to impede axonal regeneration after SCI. Moreover, some extracellular molecules produced by glial scar are also regarded as axonal growth inhibitors. With the development of technology and the progress of research, multiple lines of new evidence challenge the pre-existing traditional notions in SCI repair, including the role of glial scar. This review briefly reviewed the history, advance, and controversy of glial scar research in SCI repair since 1930s, hoping to recognize the roles of glial scar and crack the international problem of SCI regeneration.
Objective To investigate the effects of Neuritin on the regeneration of the neural axons after acute spinal cord injury (SCI) in rats. Methods The model of acute SCI at T10 was establ ished in 54 adult healthy Wistar rats (half males and half females) weighing 250-300 g by using the improved Allen’s weight-drop method. The rats were randomly dividedinto 3 groups. 100 μL (6 μg) Neuritin and His protein was injected into group A (n=24) and group B (n=24), respectively,through subarachnoid catheter. Six rats from each group were killed 3, 7, 14, and 28 days after injury to receive Basso, Beattie and Bresnahan (BBB) locomotor rating scal ing, HE staining observation, and immunohistochemistry staining observation for neurofilament 200 (NF-200) and growth associated protein 43 (GAP-43). Group C (n=6) served as sham-operated group receiving laminectomy without spinal injury and with an empty catheter in the subarachnoid space and received the above observations 7 days after injury. Results BBB scale: after operation, the scale of groups A and B was increased over time; group A was significantly higher than group B from 14 days (P lt; 0.05); group C was higher than groups A and B at different time points after operation (P lt; 0.05). HE staining: in group C, the injured spinal tissue was normal after operation; from 7 days after operation, group A presented deeper-stained nissl body, less physal iferous cells, and more nerve synapses when compared with group B. NF-200 and GAP-43 immunohistochemistry observation: in group C, there was just l ittle positive expression; while in groups A and B, positive expression of NF-200 and GAP-43 was evident in the spinal cord from 7 days after operation. Mean density integral absorbency (IA) value of NF-200 and GAP-43: group A was higher than group B at each time point (P lt; 0.05) and group C was lower than groups A and B at each time point (P lt; 0.05). Conclusion Local application of exogenous Neuritin can promote the axonal regeneration after acute SCI in rats and the recovery of the locomotion function of hind-limbs in rats.