Objective To explore an effect of the artificial nerve graft wrapped in the pedicled greater omentum on the early revascularization and an effectof the increased blood supply to the artificial nerve graft on the nerve regeneration. Methods Seventy-five rabbits were randomized into 3 groups, in which there were 2 experimental groups where the rabbits were made to abridge respectively with the artificial nerve grafts wrapped in the pedicled greater omentum (Group A) and with the artificial nerve grafts only (Group B), and the control group where the rabbits were abridged with the autologous nerve (Group C).On the 3rd, 7th and 14th days after operation, the evans blue bound to albumin (EBA) was injected into the vessels in all the grafts to show their revascularization. Twelve weeks after operation the nerve regeneration was evaluated with theelectrophysiological and histological observations on the serial sections, and was evaluated also with the transmission electron microscope. Results The artificial nerve grafts wrapped in the pedicled greater omentum in Group A and the autologous nerve grafts in Group C showed a beginning of revascularization on the3rd day after operation, and the revascularization was increased on the 7th and14th days. Compared with Groups A and C, the artificial nerve grafts in Group Bshowed a delayed revascularization on the7th day after operation. At 12 weeks after operation, there were no significant differences in the motor never conduction velocity, density of the regenerated myelinated nerve fibers, myelin sheath thickness, and diameter between Group A and Group C(Pgt;0.05). However, both Group A and Group C were superior to Group B in the above variables, with significant differences(Plt;0.05). Conclusion Utilization of the pedicled greater omentum to wrapthe artificialnerve grafts can promote an early revascularization of the artificial nerve graft and an early nerve regeneration of the artificial nerve graft because of an enhanced blood supply to the nerve graft.
OBJECTIVE Following the delayed repair of peripheral nerve injury, the cell number of anterior horn of the spinal cord and its ultrastructural changes, motorneuron and its electrophysiological changes were investigated. METHODS In 16 rabbits the common peroneal nerves of both sides being transected one year later were divided into four groups randomly: the degeneration group and regeneration of 1, 3 and 5 months groups. Another 4 rabbits were used for control. All transected common peroneal nerves underwent epineural suture except for the degeneration group the electrophysiological examination was carried out at 1, 3 and 5 months postoperatively. Retrograde labelling of the anterior horn cells was demonstrated and the cells were observed under light and electronmicroscope. RESULTS 1. The number of labelled anterior horn cell in the spinal cord was 45% of the normal population after denervation for one year (P lt; 0.01). The number of labelled cells increased steadily from 48% to 57% and 68% of normal values at 1, 3 and 5 months following delayed nerve repair (P lt; 0.01). 2. The ultrastructure of the anterior horn cells of the recover gradually after repair. 3. With the progress of regeneration the latency become shortened, the conduction velocity was increased, the amplitude of action potential was increased. CONCLUSION Following delayed repair of injury of peripheral nerve, the morphology of anterior horn cells of spinal cord and electrophysiological display all revealed evidence of regeneration, thus the late repair of injury of peripheral nerve was valid.
Objective To summarize the research progress of controlled release of angiogenic factors and osteogenic factors in bone tissue engineering. Methods The domestic and abroad literature on the controlled release structure of growth factors during bone regeneration in recent years was extensively reviewed and summarized. Results The sustained-release structure includes direct binding, microsphere-three-dimensional scaffold structure, core-shell structure, layer self-assembly, hydrogel, and gene carrier. A sustained-release system composed of different sustained-release structures combined with different growth factors can promote bone regeneration and angiogenesis. Conclusion Due to its controllability and persistence, the growth factor sustained-release system has become a research hotspot in bone tissue engineering and has broad application prospects.
Objective To give a prel iminary experimental evidence and to prove chitosan and allogeneic morsel ized bone as potential bone substitutions in repairing rabbit radius segmental defect. Methods Chitosan and allogeneic morsel ized bone were mixed with various ratios (1 ∶ 5, 1 ∶ 10, 1 ∶ 25, 1 ∶ 50, and 1 ∶ 100). After preparation, the physicaland chemical properties of the composites were prel iminary detected; the composites at the ratios of 1 ∶ 50 and 1 ∶ 25 had good physical and chemical properties and were used for the animal experiment. The radius segmental defects of 15 mm in length were made in 50 adult New Zealand white rabbits (weighing 2.5-3.0 kg), then the animals were divided into 2 groups. In groups A and B, chitosan/allogeneic morsel ized bone composites were implanted at the ratio of 1 ∶ 50 and 1 ∶ 25, respectively. After 1, 2, 4, 8, and 12 weeks of operation, the gross, histological, immunohistochemical observations were performed. Before the rabbits were sacrified, X-ray films were taken; the serum calcium and alkal ine phosphatase (ALP) concentration were measured; and the biomechanical measurement was carried out at 12 weeks. Results The results of gross observation were essentially consistent with those of the X-ray films. The histological observation showed that the bone formation was earl ier in group A than in group B; the amount of new bone formation in group A was more than that in group B; and the bone forming area in group A was bigger than that in group B (P lt; 0.05) at 4 and 8 weeks after operation. The immunohistochemical staining showed that vascular endothel ial growth factor and insul in-l ike growth factor receptor II proteins expressed in the cytoplasm of 2 groups after 4 and 8 weeks, and the expression in group A was higher than that in group B (P lt; 0.05). There was no significant difference in the serum calcium concentration between 2 groups at each time point (P gt; 0.05). After 4 and 8 weeks, the ALP concentration in group A was significantly higher than that in group B (P lt; 0.05). After 12 weeks, the radius maximum bending loads of groups A and B were (299.75 ± 27.69) N and (278.54 ± 17.09) N, respectively, showing significant difference (t=4.045,P=0.002). Conclusion The composite of chitosan and allogeneic morsel ized bone has good osteogeneic activity and can beused as a bone tissue engineering scaffold, and the optimum ratio of chitosan to allogeneic morsel ized bone was 1 ∶ 50.
ObjectiveTo summarize the regulatory role of long non-coding RNA (lncRNA) in peripheral nerve injury (PNI) and neural regeneration.MethodsThe characteristics and mechanisms of lncRNA were summarized and its regulatory role in PNI and neural regeneration were elaborated by referring to relevant domestic and foreign literature in recent years.ResultsNeuropathic pain and denervated muscle atrophy are common complications of PNI, affecting patients’ quality of life. Numerous lncRNAs are upregulated after PNI, which promote the progress of neuropathic pain by regulating nerve excitability and neuroinflammation. Several lncRNAs are found to promote the progress of denervated muscle atrophy. Importantly, peripheral nerve regeneration occurs after PNI. LncRNAs promote peripheral nerve regeneration through promoting neuronal axonal outgrowth and the proliferation and migration of Schwann cells.ConclusionAt present, the research on lncRNA regulating PNI and neural regeneration is still in its infancy. The specific mechanism remains to be further explored. How to achieve clinical translation of experimental results is also a major challenge for future research.
In order to observe the effects of different facing directions of the germinal layer of periosteum on the cartilage regeneration, the human fibrin adhesive agent was used to adhere autogenous periosteum to repair the articular cartilage defect of rabbits. Twentyfour rabbits with 48 knee joints were divided randomly into two groups. A 0.6cm×1.2cm articular cartilage defect was created on the femoral trochlea until there was bleeding from the subchondral bone. A piece of periosteum, sized 0.75cm×1.5cm, was removed from the medial aspect of upper tibia. The periosteum was adhered to the defect by human fibrin adhesive agent. In Group 1 the germinal layer faced the subchondral bone and in Group 2 the germinal layer faced the joint cavity. The cartilage regeneration in both groups was observed by naked eyes and light microscope in 2nd and 6th weeks and by electron microscope after Safronin Ostained in 12th and 20th weeks. The results showed that before the 6th week, the cartilage regeneration was faster in Group 2 than that in Group 1. After that there was no significant difference in regeneration between the two groups. This suggested that the facing direction of the germinal layer was not a critical factor on cartilage regeneration. It was also found that the strength of the adhesive agent was not enough. The regenerated cartilage was proved to be hyaline cartilage.
ObjectiveTo construction the telmisartan/collagen/polycaprolactone (PCL) nerve conduit and assess its effect on repairing sciatic nerve defect in rats. Methods The 60% collagen/hexafluoroisopropanol (HFIP) solution and 40% PCL/HFIP solution were prepared and mixed (collagen/PCL solution). Then the 0, 5, 10, and 20 mg of telmisartan were mixed with the 10 mL collagen/PCL solution, respectively. Telmisartan/collagen/PCL nerve conduits were fabricated via high voltage electrospinning technology. The structure of nerve conduit before and after crosslinking was observed by using scanning electron microscope (SEM). The drug release efficiency was detected by in vitro sustained release method. RAW264.7 cells were cultured with lipopolysaccharide to induce inflammation, and then co-cultured with nerve conduits loaded with different concentrations of telmisartan for 24 hours. The mRNA expressions of inducible nitric oxide synthase (iNOS) and Arginase 1 (Arg-1) were detected by using real-time fluorescence quantitative PCR. Forty adult Wistar rats were randomly divided into 4 groups (n=10). After preparing 15-mm-long sciatic nerve defect, the defect was repaired by cross-linked nerve conduits loaded with 0, 5, 10, and 20 mg telmisartan in groups A, B, C, and D, respectively. After operation, the general condition of rats was observed after operation; the sciatic function index (SFI) was tested; the bridging between the nerve conduit and sciatic nerve, and the integrity of nerve conduit were observed; the tissue growth in nerve conduit and material degradation were observed by HE staining; the expressions of CD86 (M1 macrophage marker), CD206 (M2 macrophage marker), myelin basic protein (MBP), and myelin protein 0 (P0) in new tissues were also observed by immunohistochemical staining; the expressions of neurofilament 200 (NF-200) and S-100β in new tissues were assessed by immunofluorescence staining. Results The general observation showed that the inner diameter of the nerve conduit was 1.8 mm and the outer diameter was 2.0 mm. After cross-linking by genipin, the nanofiber became thicker and denser. The drug release test showed that the telmisartan loaded nerve conduit could be released gradually. With the increase of telmisartan content in nerve conduit, the iNOS mRNA expression decreased and the Arg-1 mRNA expression increased; and the differences between 20 mg group and other groups were significant (P<0.05). In vivo experiment showed that all animals in each group survived until the completion of the experiment. The SFI was significantly higher in groups C and D than in groups A and B at different time points (P<0.05) and in group D than in group C at 6 months after operation (P<0.05). HE staining showed that there were significantly more new tissues in the middle of the nerve conduit in group D after operation than in other groups. Immunohistochemical staining showed that CD86 and CD206 stainings were positive in each group at 1 month after operation, among which group D had the lowest positive rate of CD86 and the highest positive rate of CD206, and there were significant differences in the positive rate of CD206 between group D and groups A, B, and C (P<0.05); the MBP and P0 stainings were positive in groups C and D at 6 months, and the positive rate in group D was significantly higher than that in group C (P<0.05). Immunofluorescence staining showed that the NF-200 and S-100β expressions in group D were significantly higher than those in other groups. ConclusionTelmisartan/collagen/PLC nerve conduit can promote the sciatic nerve defect repair in rats through promoting the polarization of M1 macrophages to M2 macrophages, and the nerve conduit loaded with20 mg telmisartan has the most significant effect.
ObjectiveTo investigate the expression regulation of inflammation cytokines interleukin 4 (IL-4), IL-6, IL-13, and tumor necrosis factor α (TNF-α) in rats with sciatic nerve defect following olfactory ensheathing cell (OEC) transplantation. MethodsThe primary OEC for cell culture and identification was dissociated from the olfactory bulb of the green fluorescent protein-Sprague Dawley (GFP-SD) rat. One hundred SD rats were randomly divided into 2 groups, and the right sciatic nerve defect (10 mm in length) model was made, then repaired with poly (lactic acid-co-glycolic acid) (PLGA). The mixture of equivalent cultured GFP-OEC and extracellular matrix (ECM) was injected into both ends of PLGA nerve conduit in the experimental group (n=55), and the mixture of DMEM and ECM in the control group (n=45). The general situation of rats was observed after operation. At 6 hours, 1 day, 3 days, 1 week, 2 weeks, 3 weeks, 4 weeks, and 6 weeks, the inflammatory cytokines were detected by Western blot. At 2, 4, and 6 weeks, the survival of GFP-OEC was observed in the experimental group. At 9 weeks, HE staining was used to observe the morphology of nerve tissue, and the sensory and motor function and the electrophysiological index were detected. ResultsThe cultured primary cells were GFP-OECs by immunofluorescence staining. Compared with the control group, the experimental group showed significantly increased expression level of IL-4 at 2-6 weeks (P < 0.05), significantly decreased expression level of IL-6 and TNF-α at 3 days and 1 week (P < 0.05) and significantly increased expression level of IL-13 at 1 day and 3-6 weeks (P < 0.05) by Western blot detection. At 2, 4, and 6 weeks, the surviving GFP-OEC of regenerative nerve end was observed in the experimental group under the fluorescence microscope. At 9 weeks, regenerative nerve tissue was loose, and cell morphology was irregular in the experimental group, while the regenerative nerve tissue had vesicular voids and the cell number decreased significantly in the control group. At 9 weeks, the functional recovery of sciatic nerve in the experimental group was better than that of the control group, showing significant difference in the lateral foot retraction time, sciatic nerve function index, muscle action potential latency, and the amplitude of compound muscle action potential (P < 0.05). ConclusionOEC can promote the anti-inflammation cytokines expression of IL-4 and IL-13 and inhibit the pro-inflammatory cytokines expression of IL-6 and TNF-α, which can improve the local inflammatory microenvironment of sciatic nerve and effectively promote the structure and function recovery of sciatic nerve.
Objective To explore the changes of calcitonin gene-related peptide (CGRP) and substance P (SP) levels after end-toend and end-to-side neurorrhaphy. Methods Twenty female Wistar rats were divided into 4 experimental groups and control group. In the experimental groups, common peroneal nerves were transected on both sides. End-to-side coaptation was performed on the left, while end-to-end coaptation on the right. After 1, 2, 4 and 27 weeks, the rats were sacrificed, and immunoreactivities of CGRP and SP in suture sites, lumbar spine and dorsal root ganglia(DRGs) were evaluated respectively. Results The expression ofCGRP and SP decreased in dorsal horn and DRGs within 1 week postoperatively. After 4 -27 weeks, CGRP and SP in dorsal horn could return to almost normal level, but they had little recovery in DRGs. Although the trend of change between end-to-end and end-to-side was coincident, in most experimental groups, thereexisted differences in the dorsal horn between end-to-end and end-to-side. The sciatic nerve stained by acetylcholinesterase, SP, CGRP and PGP 9.5 showed that the fibers could pass through the suture site of either end-to-end or end-to-side. Conclusion Nerve regeneration can be achieved by end-to-side neurorrhaphy, andthe mechanism of sensory nerve recovery of these two methods is similar. But the recovery in end-to-side coaptation is insufficient to some degree.
ObjectiveBased on the cell-extracellular matrix adhesion theory in selective cell retention (SCR) technology, demineralized bone matrix (DBM) modified by simplified polypeptide surface was designed to promote both bone regeneration and angiogenesis.MethodsFunctional peptide of α4 chains of laminin protein (LNα4), cyclic RGDfK (cRGD), and collagen-binding domain (CBD) peptides were selected. CBD-LNα4-cRGD peptide was synthesized in solid phase and modified on DBM to construct DBM/CBD-LNα4-cRGD scaffold (DBM/LN). Firstly, scanning electron microscope and laser scanning confocal microscope were used to examine the characteristics and stability of the modified scaffold. Then, the adhesion, proliferation, and tube formation properties of CBD-LNα4-cRGD peptide on endothelial progenitor cells (EPCs) were detected, respectively. Western blot method was used to verify the molecular mechanism affecting EPCs. Finally, 24 10-week-old male C57 mice were used to establish a 2-mm-length defect of femoral bone model. DBM/LN and DBM scaffolds after SCR treatment were used to repair bone defects in DBM/LN group (n=12) and DBM group (n=12), respectively. At 8 weeks after operation, the angiogenesis and bone regeneration ability of DBM/LN scaffolds were evaluated by X-ray film, Micro-CT, angiography, histology, and immunofluorescence staining [CD31, endomucin (Emcn), Ki67].ResultsMaterial related tests showed that the surface of DBM/LN scaffold was rougher than DBM scaffold, but the pore diameter did not change significantly (t=0.218, P=0.835). After SCR treatment, DBM/LN scaffold was still stable and effective. Compared with DBM scaffold, DBM/LN scaffold could adhere to more EPCs after the surface modification of CBD-LNα4-cRGD (P<0.05), and the proliferation rate and tube formation ability increased. Western blot analysis showed that the relative expressions of VEGF, phosphorylated FAK (p-FAK), and phosphorylated ERK1/2 (p-ERK1/2) proteins were higher in DBM/LN than in DBM (P<0.05). In the femoral bone defect model of mice, it was found that mice implanted with DBM/LN scaffold had stronger angiogenesis and bone regeneration capacity (P<0.05), and the number of CD31hiEmcnhi cells increased significantly (P<0.05).ConclusionDBM/LN scaffold can promote the adhesion of EPCs. Importantly, it can significantly promote the generation of H-type vessels and realize the effective coupling between angiogenesis and bone regeneration in bone defect repair.