ABSTRACT
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 ( P0.05). 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 ( P0.05］. 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.
ABSTRACT
BACKGROUND:The thermosensitive chitosan is a kind of chitosan, its hemostatic effect, tissue compatibility andin vivo absorption need further investigations. OBJECTIVE:To investigate the hemostasis,in vivo degradation and tissue compatibility of thermosensitive chitosan hemostatic film. METHODS: A total of 48 Sprague-Dawley rats were randomly divided into four groups, and carried out two experiments at the same time. (1) The incisions of the liver in three groups were covered with the thermosensitive chitosan hemostatic film, celulose hemostatic cotton and gelatin sponge, respectively. Blank control group received no treatment. The bleeding time and bleeding amount were recorded. (2) The incisions of the quadriceps femoris muscle of rats in the above three groups were embedded with the same hemostatic materials respectively. Blank control group was not embedded. At 1, 2, 3, 4, 6 weeks, the incision tissues of the liver and the quadriceps femoris muscle were harvested for observation. After 4 weeks, the incisions were observed with hematoxylin- eosin staining and transmission electron microscopy. RESULTS AND CONCLUSION: The bleeding time and bleeding amount of thermosensitive chitosan hemostatic film and celulose hemostatic cotton groups were significantly lower than those of gelatin sponge and blank control groups (P microscopy, the liver cels had integral structure, cellnucleus and organeles remained intact. The muscle fibers showed complete structure and little inflammatory cellinfiltration. Under transmission electron microscopy, the muscle fibers ranked tidily, with integral cellnucleus and organeles. The thermosensitive chitosan hemostatic film has good hemostasis effect and tissue compatibility.
ABSTRACT
ObjectiveTo investigate the effects of chitosan/PVA nerve conduits which used for repairing sciatics nerve defect in rats.MethodsTwenty-seven rats were divided into 3 groups randomly,with 9 rats in each group. Firstly, the 15mm defects in the left sciatic nerves were made in the rats and were respectively repaired with chitosan/PVA conduits graft (group A), the silicon conduits graft (group B),and autografts (group C). At 12 weeks after the operations, the left sciatic nerves were taken out, and the comparative evaluation was made on the repairing effects by wet weight of gastrocnemius and soleus muscles, histological examination,computerized imaging analysis and True Blue retrograde tracing. ResultsThe wet weight of gastrocnemius and soleus muscles showed no significant difference between the chitosan/PVA graft and autograft groups (P ＞ 0.05). The wet weight of gastrocnemius and soleus muscles in significant difference between the chitosan/PVA graft and the silicon group at 12 weeks after the operation(P ＜ 0.05). The nerve fiber density showed no statistically significant differences between the chitosan/PVA and autograft groups(P＞ 0.05).The regenerative nerve fiber in group B had normal morphological and structural characters under transmission electron microscope.True Blue-labeled neuron cell bodies were found within both anterior horn of gray matter in the spinal cord and dorsal root ganglions (DRGs) ipsilateral to the operated side of the tested rats on illumination with ultra-violet light 1 week after the injection of True Blue.Conclusion Chitosan/PVA nerve conduit can effectively promote the nerve regeneration and myelinization of rat sciatic nerve, which is expected to substitute for autograft to repair nerve defects succesfully.
ABSTRACT
Effects of carboxymethyl-chitosan (CM-Chitosan) with different molecular weight on the proliferation of skin fibroblasts and keratinocytes were examined in vitro; bFGF and EGF, as controls, were seperately used for comparison. Chitosan with different molecular weight was prepared by acid degradation and oxidation degradation; CM-Chitosan with different molecular weight was synthesized from corresponding Chitosan. Microscopy and MTT method were applied to evaluate the different effects. The results demonstrated that CM-Chitosan with different molecular weight promoted the proliferation of skin fibroblasts and keratinocytes at 1-1000 ppm, and the concentration at 100 ppm had the strongest effects. The effects of low molecular weight CM-Chitosan were greater than those of high molecular weight CM-Chitosan. CM-Chitosan (Mn= 3KD) had the strongest promotive effects on skin fibroblasts and keratinocytes; it had equivalent effects when compared with bFGF and EGF.
Subject(s)
Animals , Humans , Mice , Cell Proliferation , Cells, Cultured , Chitosan , Pharmacology , Fibroblasts , Cell Biology , Keratinocytes , Cell Biology , Molecular Weight , Skin , Cell BiologyABSTRACT
Objective To evaluate the safety,clinical and financial aspects of laparoscopic cholecystectomy(LC).Methods 278 cases undergone LC and 234 cases undergone open cholecystectomy(OC)were compared in retrospective study.Results LC was as safe as OC.In favour of LC,significant differences were observed regarding the time of severe pain,hospitalization and recovery.The total occurences of postoperative complications were low in all the patients undergone LC or OC,and its significantly lower in patients undergone LC than that in those undergone OC.Furthermore,the total charges for LC were significantly lower than that for OC.Conclusions LC is as safe as OC and has clan obvious advantage over OC in clinical,social and financial aspects.