Objective To study the result of using nerve conduit coated with chitin and filled with a guide-fiber to repair peripheral nerve defect. Methods Twenty-four female adult SD rats were made the model of 14 mm-gap on bilateral sciatic nerve under sterile condition. The rats were randomly divided into 4 groups(n=6),group A: polymer polyglycolic-lactic acid(PGLA) nerve conduit coated with chitin and filled with a guide-fiber as experimental group to repair 14 mm gap of rat sciatic nerve；group B: PGLA nerve conduit coated with chitin； group C: PGLA nerve conduit； group D: autograft (control group). The repair result was evaluated by normal observation, EMG testing and S-100 histological immunostaining analysis 4 and 12 weeks after operation.Results Four weeks after the operation，there were new regenerated immature fibers in groups A,B and C, 12 weeks after the operation, the regenerated nerve fibers were seen to have bridged the gap. There were myelinated fibers equably distributed and rarely newgenerated nerve fibers in distal parts of group D. The repair result of PGLA nerve conduit coated with a chitin and filled with guide-fiber was better than that of groups B and C（Plt;0.05）. There was significant difference of nerve fiber diameter，thickness of myelin sheath and fiber density in group D from those in groups A, B and C（Plt;0.05），but there were degenerative changes such as vacuoles insheaths and myelin separation in proximal and few new regenerated nerve fibers in distal parts of group D. Conclusion PGLA nerve conduit coated with chitin and filled with a guide-fiber offers a possible substitute for the repair of peripheral nerve defect.
Objective Comparing postoperative change of blood gas and hemodynamic status in patients underwent a right ventricletopulmonary artery (RVPA) conduit or a modified BlalockTaussig (mBT) shunt for pulmonary atresia with ventricular septal defect and without major arterial pulmonary collaterals (MAPCAs), to affirm the effect on oxygen supply /demand with different procedure. Methods From July 2006 to October 2007, 38 patients with pulmonary atresia and ventricular septal defect without MAPCAs were divided into two groups according to different procedures: RVPA group (n=25) and mBT group (n=13).Perioperative mortality, blood gas and hemodynamic data during postoperative 48 hours, including heart rate, blood pressure, systemic oxygen saturation, mixed venous oxygen saturation, oxygen excess factor, inotropic score were compared in both groups. Results The difference in the mortality between RVPA group (4.0％，1/25) and mBT group （7.7％，1/13) showed no statistical significance（Pgt;0.05）. The total of 33 patients were followed up, the followup time was from 6 to 18 months.11 patients (4 patients in mBT group, 7 patients in RVPA group) underwent corrected procedures during 9 to 18 months after palliative procedures, one case died of elevated pulmonary vascular resistance and right ventricle failure. The mixed venous oxygen saturation at 24h and 48h after surgery were higher than that at 6h after surgery (Plt;0.01) both in RVPA group and mBT group. The systolic blood pressures at 6h, 24h, 48h after surgery in RVPA group were lower than those in mBT group (P=0.048，0.043， 0.045)，the mean systemic blood pressures in RVPA group were higher than those in mBT group (P=0.048, 0.046, 0.049),the diastolic blood pressures in RVPA group were higher than those in mBT group (P=0.038, 0.034, 0.040)， the inotropic scores in RVPA group were lower than those in mBT group (P=0.035， 0.032，0.047). Conclusion The blood pressures and inotropic scores are found significantly different in RVPA conduit and mBT procedures, while postoperative systemic oxygen delivery areequivalent. Both RVPA and mBT patients decline to nadir in hemodynamic status at 6 h after surgery.
ObjectiveTo investigate the effect of folic acid coated-crosslinked urethane-doped polyester elastomer (fCUPE) nerve conduit in repairing long distance peripheral nerve injury. MethodsThirty-six 3-month-old male Sprague Dawley rats weighing 180-220 g were randomly assigned to 3 groups, each consisting of 12 rats: CUPE nerve conduit transplantation group (group A), fCUPE nerve conduit transplantation group (group B), and autologous nerve transplantation group (group C), the contralateral healthy limb of group C served as the control group (group D). A 20-mm-long sciatic nerve defect model was established in rats, and corresponding materials were used to repair the nerve defect according to the group. The sciatic function index (SFI) of groups A-C was calculated using the Bain formula at 1, 2, and 3 months after operation. The nerve conduction velocity (NCV) of the affected side in groups A-D was assessed using neuroelectrophysiological techniques. At 3 months after operation, the regenerated nerve tissue was collected from groups A-C for S-100 immunohistochemical staining and Schwann cell count in groups A and B to compare the level of nerve repair and regeneration in each group. ResultsAt 3 months after operation, the nerve conduits in all groups partially degraded. There was no significant adhesion between the nerve and the conduit and the surrounding tissues, the conduit was well connected with the distal and proximal nerves, and the nerve-like tissues in the conduit could be observed when the nerve conduit stents were cut off. SFI in group A was significantly higher than that in group C at each time point after operation and was significantly higher than that in group B at 2 and 3 months after operation (P<0.05). There was no significant difference in SFI between groups B and C at each time point after operation (P>0.05). NCV in group A was significantly slower than that in the other 3 groups at each time point after operation (P<0.05). The NCV of groups B and C were slower than that of group D, but the difference was significant only at 1 month after operation (P<0.05). There was no significant difference between groups B and C at each time point after operation (P>0.05). Immunohistochemical staining showed that the nerve tissue of group A had an abnormal cavo-like structure, light tissue staining, and many non-Schwann cells. In group B, a large quantity of normal neural structures was observed, the staining was deeper than that in group A, and the distribution of dedifferentiated Schwann cells was obvious. In group C, the nerve bundles were arranged neatly, and the tissue staining was the deepest. The number of Schwann cells in group B was (727.50±57.60) cells/mm2, which was significantly more than that in group A [(298.33±153.12) cells/mm2] (t=6.139, P<0.001). ConclusionThe fCUPE nerve conduit is effective in repairing long-distance sciatic nerve defects and is comparable to autologous nerve grafts. It has the potential to be used as a substitute material for peripheral nerve defect transplantation.
ObjectiveTo describe the research progress of silk-based biomaterials in peripheral nerve repair and provide useful ideals to accelerate the regeneration of large-size peripheral nerve injury. Methods The relative documents about silk-based biomaterials used in peripheral nerve regeneration were reviewed and the different strategies that could accelerate peripheral nerve regeneration through building bioactive microenvironment with silk fibroin were discussed. Results Many silk fibroin tissue engineered nerve conduits have been developed to provide multiple biomimetic microstructures, and different microstructures have different mechanisms of promoting nerve repair. Biomimetic porous structures favor the nutrient exchange at wound sites and inhibit the invasion of scar tissue. The aligned structures can induce the directional growth of nerve tissue, while the multiple channels promote the axon elongation. When the fillers are introduced to the conduits, better growth, migration, and differentiation of nerve cells can be achieved. Besides biomimetic structures, different nerve growth factors and bioactive drugs can be loaded on silk carriers and released slowly at nerve wounds, providing suitable biochemical cues. Both the biomimetic structures and the loaded bioactive ingredients optimize the niches of peripheral nerves, resulting in quicker and better nerve repair. With silk biomaterials as a platform, fusing multiple ways to achieve the multidimensional regulation of nerve microenvironments is becoming a critical strategy in repairing large-size peripheral nerve injury. Conclusion Silk-based biomaterials are useful platforms to achieve the design of biomimetic hierarchical microstructures and the co-loading of various bioactive ingredients. Silk fibroin nerve conduits provide suitable microenvironment to accelerate functional recovery of peripheral nerves. Different optimizing strategies are available for silk fibroin biomaterials to favor the nerve regeneration, which would satisfy the needs of various nerve tissue repair. Bioactive silk conduits have promising future in large-size peripheral nerve regeneration.
OBJECTIVE To explore the effect of basic fibroblast growth factor (bFGF) combined with autogenous vein graft conduit on peripheral nerve regeneration. METHODS Fifty four New Zealand rabbits were divided into three groups. The main trunk of sciatic nerve of rabbit in one side was severed and bridged by autogenous vein. 0.2 ml bFGF solution (4,000 U/ml) was intravenously injected to the vein graft conduit as group A, the same amount of saline solution as group B, and no solution injection as group C. Microscopic examination, axon video analysis and nerve conduct velocity were performed at the 10th, 30th, and 100th day after operation. RESULTS The nerve fibers were grown into vein graft conduit in all groups at 30th after operation, they were more and regular in group A than that of group B and C, and the axon regeneration rate in group A was more than that of group B and C. CONCLUSION bFGF combined with autogenous vein graft conduit can markedly promote nerve regeneration.
Objective To review the research progress on silk fibroin (SF)-nerve guidance conduits (NGCs) for peripheral nerve injury (PNI) repair. Methods To review the recent literature on PNI and SF-NGCs, expound the concepts and treatment strategies of PNI, and summarize the construction of SF-NGCs and its application in PNI repair. Results Autologous nerve transplantation remains the “gold standard” for treating severe PNI. However, it’s clinical applications are constrained by the limitations of limited donors and donor area damage. Natural SF exhibits good biocompatibility, low immunogenicity, and excellent physicochemical properties, making it an ideal candidate for the construction of NGCs. SF-NGCs constructed using different technologies have been found to have better biocompatibility and bioactivity. Their configurations can facilitate nerve regeneration by enhancing regenerative guidance and axonal extension. Besides, the adhesion, proliferation and differentiation of neurons and Schwann cells related to PNI repair can be effectively promote by NGCs. This accelerates the speed of nerve regeneration and improves the efficiency of repair. In addition, SF-NGCs can be used as regenerative scaffolds to provide biological templates for nerve repair. Conclusion The biodegradable natural SF has been extensively studied and demonstrated promising application prospects in the field of NGCs. It might be an effective and viable alternative to the “gold standard” for PNI treatment.
Objective\ To search for suitable and multiple arterial grafts for myocardial revascularization, in order to avoid the long term problems of vein graft atherosclerosis. Methods\ Between October 1994 and April 2000, 456 consecutive patients underwent myocardial revascularization using radial artery and internal mammary artery. In coronary artery bypass grafting, minimally traumatic harvesting radial artery techniques and new pharmacologic antispasmodic agents was used. Results\ 448 internal mammary artery ...
ObjectiveTo study the effect of the loaded concentration gradient of nerve growth factor (NGF) immobilized conduit on rat peripheral nerve defect repair.
MethodsThe peripheral nerve conduits made of poly (ε-caprolactone)-block-poly (L-lactide-co-ε-caprolactone) were prepared with uniform loads or concentration gradient loads by combining differential absorption of NGF/silk fibroin (SF) coating, and the gradient of NGF was immobilized in the nerve conduits. ELISA method was used to exam the NGF release for 12 weeks in vitro. Twenty-four male Sprague Dawley rats (weighing, 220-250 g) were selected to establish the right sciatic nerve defect model (14 mm in length) and randomly divided into 4 groups according to repair methods. The transected nerve was bridged by a blank conduit without NGF in group A, by a conduit containing uniform loads of NGF in group B, by a conduit concentration gradient loads of NGF in group C, and by the autogenous nerve segment in group D. The gross observation, electrophysiological examination, histological observation, and transmission electron microscope observation were carried out to assess the nerve regeneration at 12 weeks after surgery.
ResultsThe cumulative release amount of NGF was (14.2±1.4) ng/mg and (13.7±1.3) ng/mg in gradient of NGF loaded conduits and uniform NGF loaded conduits respectively at 12 weeks, showing no significant difference (t=0.564, P=0.570). All the animals survived to completion of the experiment; plantar ulcers occurred at 4 days, which healed at 12 weeks; groups C and D were better than groups A and B in ulcerative healing. At 12 weeks after surgery, the compound muscle action potential of group A was significantly lower than that of groups B, C, and D (P<0.05), and group B was significantly lower than groups C and D (P<0.05), but no significant difference was found between groups C and D (P>0.05). The axon density of group C was significantly higher that of groups A, B, and D (P<0.05); group D was significantly higher than groups A, B, and C, and group C was significantly higher than groups A and B in the axon number, axon diameter, and area of muscle fiber (P<0.05); the thickness of myelin sheath of groups C and D was significantly larger than that of groups A and B (P<0.05), but no significant difference was found between groups C and D (P>0.05).
ConclusionGradient of NGF loaded nerve condnits for rat sciatic nerve defect has similar results to autogenous nerve, with a good bridge, which can promote the sciatic nerve regeneration, improve the myelinization of the regenerating nerve, and accelerate the function reconstruction of the regenerating nerve.
The choice of the graft conduit for coronary artery bypass grafting (CABG) has significant implications both in the short-and long-term. The patency of a coronary conduit is closely associated with an uneventful postoperative course, better long-term patient survival and superior freedom from re-intervention. The internal mammary artery is regarded as the primary conduit for CABG patients, given its association with long-term patency and survival. However, long saphenous vein (LSV) continues to be utilized universally as patients presenting for CABG often have multiple coronary territories requiring revascularization. Traditionally, the LSV has been harvested by creating incisions from the ankle up to the groin termed open vein harvesting (OVH). However, such harvesting methods are associated with incisional pain and leg wound infections. In addition, patients find such large incisions to be cosmetically unappealing. These concerns regarding wound morbidity and patient satisfaction led to the emergence of endoscopic vein harvesting (EVH). Published experience comparing OVH with EVH suggests decreased wound related complications, improved patient satisfaction, shorter hospital stay, and reduced postoperative pain at the harvest site following EVH. Despite these reported advantages concerns regarding risk of injury at the time of harvest with its potential detrimental effect on vein graft patency and clinical outcomes have prevented universal adoption of EVH. This review article provides a detailed insight into the technical aspects, outcomes, concerns, and controversies associated with EVH.
Objective To explore a green route for the fabrication of thermo-sensitive chitosan nerve conduits, improve the mechanical properties and decrease the degradation rate of the chitosan nerve conduits. Methods Taking advantage of the ionic specific effect of the thermo-sensitive chitosan, the strengthened chitosan nerve conduits were obtained by immersing the gel-casted conduits in salt solution for ion-induced phase transition, and rinsing, lyophilization, and 60Co sterilization afterwards. The nerve conduits after immersing in NaCl solutions for 0, 4, 12, 24, 36, 48, and 72 hours were obtained and characterized the general observation, diameters and mechanical properties. According to the above results, the optimal sample was chosen and characterized the microstructure, degradation properties, and cytocompatibility. The left sciatic nerve defect 15 mm in length was made in 20 male Sprague Dawley rats. The autologous nerves (control group, n=10) and the nerve conduits (experimental group, n=10) were used to repair the defects. At 8 weeks after operation, the compound muscle action potential (CMAP) was measured. The regenerated nerves were investigated by gross observation and toluidine blue staining. The gastrocnemius muscle was observed by HE staining. Results With the increased ionic phase transition time, the color of the conduit was gradually deepened and the diameter was gradually decreased, which showed no difference during 12 hours. The tensile strength of the nerve conduit was increased gradually. The ultimate tensile strength showed significant difference between the 48 hours and 12, 24, and 36 hours groups (P<0.05), and no significant difference between the 48 hours and 72 hours groups (P>0.05). As a result, the nerve conduit after ion-induced phase transition for 48 hours was chosen for further study. The scanning electron microscope (SEM) images showed that the nerve conduit had a uniform porous structure. The degradation rate of the the nerve conduit after ion-induced phase transition for 48 hours was significantly decreased as compared with that of the conduit without ion-induced phase transition. The nerve conduit could support the attachment and proliferation of rat Schwann cells on the inner surface. The animal experiments showed that at 8 weeks after operation, the CMAPs of the experimental and control groups were (3.5±0.9) and (4.3±1.1) m/V, respectively, which showed no significant difference between the two groups (P<0.05), and were significantly lower than that of the contralateral site ［(45.6±5.6 m/V), P>0.05］. The nerve conduit of the experimental group could repair the nerve defect. There was no significant difference between the experimental and control groups in terms of the histomorphology of the regenerated nerve fibers and the gastrocnemius muscle. Conclusion The green route for the fabrication of thermo-sensitive chitosan nerve conduits is free of any toxic reagents, and has simple steps, which is beneficial to the industrial transformation of the chitosan nerve conduit products. The prepared chitosan nerve conduit can be applied to rat peripheral nerve defect repair and nerve tissue engineering.
