Chitin was used as the stuffing material bonedefect in animal experiment. Radiological and his-tological examination showed that it had good bi-ologgical compatibility good strength, hemostaticeffect promoting tussue healing and no toxicity.Chitin could be degradated by enzyme and mightbe used as the bone supporting material for treament of bone defect.
The biomaterial, chitin, was used to create a nerve regeneration chamber for bridging healing experiment of sciatic nerve of rats having a defect of 12mm. The crude Schwann cells were introduced into the chambers in one group and the other group had no crude Schwann cells in the chamber and the results of the two groups were compared with those having the nerve defects bridged with skeletal muscles. The specimens were observed by macroscopic, microdissection. electrophysiologic testing, HRP retrograde labelling, histologic and electron microscopic examinations at 4, 8, and 12 weeks after the operation. The results showed that atthe 8th week, the regenerating nerve fibers from the cephalad ends had united with the fibers of the caudal ends of the divided nerves either the crude Schwanneclls were introduced or not, but the morphology of the regenerating nerve, the way of regeneration and the recovery of the function of the extremities were far superior in the group that no cruds Schwann cells had been introduced than those with crude Schwann cell introduced and those bridged by skeletal muscles.
In this experiment, two proximal ends of themedian and ulnar nerves of rabbit wereapproxirnated within the chitin tube for thepurpose to inhibit the neuroma formation. Byobservation under light and transmission electronmicrnscopo and immunohistochemistry, wefound that: (1) the axons of the two proximalstumpe could regenerate in the chitin tube for 2to 5mm, and then ceased to grow when anaxonal overlap happened resulting in inhibitingneuroma formation; (2) chitin tube could bedegradated a...
OBJECTIVE: To investigate the feasibility of the chitosan-collagen membrane (CCM) as a dermal substitute. METHODS: Fresh bovine tendo calcaneus collagen was dispersed in 0.5 mol/L acetic acid, co-precipitated with chitosan and lyophilized. Dry membranes were cross-linked in 0.05% glutaraldehyde for 24 hours. In vitro its degrading rate was measured by use of collagenase degrading test. The chitosan-collagen membrane was implanted to subcutaneous dorsal sites of SD rats. After implantation, histocompatibility, vascularity and degradation were observed in vivo. RESULTS: The chitosan-collagen membrane was yellowish, translucent, and porous. Pore size ranged 50-250 microns, and collagen fiber bundles were reticular arrangement in the membrane. It had slower degradation than pure collagen membrane by collagenase in vitro. Subcutaneous implantation test showed the minimal inflammation, good histocompatibility and earlier vascularization. The membrane degradation was slower in vivo. Eight weeks after implantation, organized collagen structure was retained. CONCLUSION: The chitosan-collagen membrane has better physical and biological properties, ideal histocompatibility, earlier vascularization and slower degradation. Therefore, It is an optimum substitute for dermal scaffold.
The chitin abstracted from silkworm chrysalis was subjected to toxicological study including: (1)systematic toxicological test, (2)pyretogenic test, (3)primary cutaneous irritative test, (4)intradermal injection test, (5)cutaneous allergic test. (6)conjunctival irritative test, (7)hemolysis test, (8)bacterial toxicity test, (9)dominant lethal test, and (10)mutagenetictest. The results showed that chitin is atoxic, non-irritative, non-allergenic, nonpyretogenic, non-hemolytic, non-mutagenic, and non-lethal mutagenic. Therefore, chitin is a compatible biomaterial for implanting into the tissue.
In order to study the effect of chitin and chitosan on the growth of Schwann cell (SC) of rats in vitro, the SC was isolated from sciatic nerve and brachial plexus of new-born rats. After the enzymatic and mechanical dissociation, the cell suspension was vaccinated on chitin membrane and chitosan fluid-coated glass coverslips. Then, the growth of SC was examined at 1, 3, 7 days after culture under light microscope and scanning electron microscope. The results showed that 94 percent of the cell grown from was SC and only 6% was fibroblast (FB), while that of the control SC 71% and FB 29% in population. The number of SC in chitosan suspension was more than that in chitin. Therefore, the conclusion was that the chitin and chitosan was histocompatible to SC, and chitosan suspension was superior to chitin, and both could inhibit the growth of fibroblast.
OBJECTIVE: To study the feasibility of α-cyanoacrylate medical adhesive in fixation of intratemporal facial nerve when nerve was repaired within chitin chamber, and to investigate the nerve regeneration. METHODS: Nerve defect of 6 mm was made in left intratemporal facial nerves of 48 rabbits. All the defects were bridged with chitin chamber and were fixed by α-cyanoacrylate medical adhesive, surgical suture and natural union. Nerve function test and histomorphological examination were carried out at 1 month and 3 months after repair. RESULTS: It was observed that the nerve was fixed firmly to the chamber with no crack or crease by α-cyanoacrylate medical adhesive. The regenerated new nerve fibers were more regular and denser and the neurological function recovered much better in the group fixed by alpha-cyanoacrylate medical adhesive than in the groups those fixed by surgical suture and natural union. CONCLUSION: The medical adhesive is b in adhesion and beneficial to nerve repair; repair of intratemporal facial nerve defect within chitin chamber fixed by alpha-cyanoacrylate medical adhesive is feasible, simple and timesaving.
OBJECTIVE: To evaluate the nerve regeneration after implantation of chitin tubes containing nerve growth factor(NGF) in the rabbit facial nerve. METHODS: Bilateral 8 mm defect of superior buccal divisions of the facial nerves were made in 16 New Zealand rabbits. Chitin tubes containing NGF were implanted into the gaps, and autologous nerves were implanted into the right gaps as control. The nerve regeneration was evaluated with electrophysiological and ultrastructural examination after 8 and 16 weeks of operation. RESULTS: Chitin tubes containing NGF successfully induced the nerve regeneration, regularly arranged myelinated and unmyelinated axons could be observed across the 8 mm gaps, and the myelin sheath was thick with clear lamellar structure at 8 weeks after operation, The regenerated nerve fibers increased and were more mature at 16 weeks after operation. There were no significant difference in electrical impulse conduction velocity through the neural regeneration between the experimental and control sides (P gt; 0.05). CONCLUSION: Chitin tubes containing NGF can provide optimal conditions for regeneration of rabbit facial nerve.
Thiry wistar rats were used and divided in 2 groups. A segment of 6mm was excised in the sciatic nerve which were then bridged with chitin and skelal muscle. at 4,8,12 weeks after operation, In the chitin group a satisfactory regeneration of nerve fibers was evident with electrophysiologic and histologic examinations, and HRP retrogade labelling evaluation. The possible mechanism of enhancing nerve regeneration of chitin was also discussed.
Objective To prepare carboxymethylchitin and study its properties. Methods Chitin was prepared from fresh shrimp shells and then carboxymethylchitin was prepared by the methods of alkalization and etherification as well as by the purification technique. The deacetylation degree of carboxymethylchitin was determined by the doublejump potentiometric titration method; the substitution degree was determined by the element analysis method; the carboxymethyl substitution position was analyzed by the Fourier transform infrared spectroscopy apparatus and the nuclear magnetic resonance spectroscopy apparatus; the relative molecular weight and its polydispersity were determined by the gel permeation chromatography with the multiple angle laser light scattering detection; the biological properties were tested according to the GB/T 16886 biological evaluation on medical devices. Results Carboxymethylchitin could be prepared by alkalization and etherification from chitin which was prepared from fresh shrimp shells by decalcification and deproteinization. The deacetylation degree of carboxymethylchitin was 13.76% according to the doublejump potentiometric titration; the degrees of deacetylation and substitution were 14.53% and 1.239 0 respectively according to the element analysis. The IR spectrum showed that the substitutive position was N,O-substitution, and the 13C-NMR spectrum showed that substitutive position of carboxymethylchitin was mostly primary substitution of 6-OH, and according to the substitutive proportion, the substitutive turns were in the following decreasing order: 6-OH, NH2, and 3-OH. The weightaveraged and the numberaveraged molecular weights and polydispersity were 6.25×105, 5.60×105 and 1.22, respectively. The results from the biological property test showed that carboxymethylchitin was a biomaterial that was sterile, pyrogen-free, acute toxicity-free, cytotoxicity-free, intracutaneous irritationfree, skin sensitization-free and biomaterial genotoxicity-free, with no side or adverse effects on the related tissues after implantation into the human body. Conclusion Carboxymethylchitin prepared from chitin by alkalization and etherification is amacromolecule biomaterial that has a low degree of deacetylation, a high degreeof substitution, and a good biocompatibility.