Objective To develop an experimental model of abdominal aorta transplantation with nano-biomimetictissue engineered blood vessel (NBTEBV) and to investige the change of histomorphology in evolutionary process of degradation and remodel ing. Methods Twenty 6-month-old New Zealand rabbits were included, weighing 2-3 kg, male or female. The autologous seed cells of rabbits were harvested to build NBTEBV in vitro. After the branch of abdominal aorta under kidney was l igated, about 10 mm abdominal aorta was cut and replaced by NBTEBV; the anastomotic stoma was marked by Ti cl ips. NBTEBV’s evolutionary processes of degradation and rebuilding were observed. Twelve weeks after operation, DSA and color Doppler examinations were made. At 1, 4 and 12 weeks after operation, the gross and histological observations were made and 14C binding in PLGA was detected with X-ray photon spectroscopy. Results Of 20 rabbits, 17 showed that the NBTEBV was patency; 3 died from NBTEBV occlusion 36 or 72 hours after operation. The results of DAS and color Doppler showed the blood flow was patency, the blood flow rate was normal and there was no angiectasis. The lumen of transplanted blood vessel was covered with monolayer endothel ial cells. At 1 week, smooth muscle cells (SMCs) arranged regularly and much PLGA distributed in the EMCs. At 4 weeks, SMCs arranged in a layer, ECM was forming, mimic ECM degraded partly; PLGA decreased obviously. At 12 weeks, the SMCs arranged regularly, ECM formed, mimic ECM degraded, no PLGA was seen in the wall, the shape of graft was similar to the natural vessel. The decreasing crest value of 14C in specimen showed the degradation of PLGA. Conclusion NBTEBV has a good surgical maneuverabil ity and histocompatibil ity, its remodel ing evolutionary process fits in with tissue engineering specification. Building NBTEBV with ELSP is feasible.
Objective To construct three kinds of collagen-chitosan porous scaffolds with enhanced biostability and to investigate the histocompatibility of the scaffolds in vivo. Methods Collagen-chitosan porous scaffolds were fabricated by freeze-drying method, cross-linked using dehydrothermal treatment and glutaraldehde, respectively. The morphology of the uncross-linked scaffold (scaffold1), dehydrothermally cross-linked scaffold (scaffold 2) and glutaraldehde crosslinked scaffold (scaffold 3) was studied by scanning electron microscopy. Threekinds of scaffolds were embedded subcutaneously on dorsal surface of 12 rabbit ears. The general and local responses were recorded daily. The biostability and histocompatibility of the scaffolds were observed by using HE staining after 3, 7, 14 and 28 days of operation. Results The scaffolds had three-dimensional porous structures with a porosity of more than 90%, and possessed pore sizes of 120±10 μm, 80±15 μm and 170±20 μm, respectively. All experimental rabbits survived with good general condition during the study. All skin incisions healed well without obvious reactive red or swelling. Histological study showed that scaffold 1 was degraded rapidly with obvious inflammation. The degradation of scaffold 2 was slower than that of scaffold 1 and the inflammation of scaffold 2 was also milder than that of scaffold 1. Scaffold 3 possessed slow degradation property with slight inflammatory reaction, and rapid tissue regeneration. Conclusion The collagenchitosan porous scaffolds have three-dimensional porous structures that are suitable for tissue regeneration. The biostability and histocompatiility of the scaffolds are enhanced after cross-linked. Glutaraldehde cross-linked is better than dehydrothermally cross-linked, which can facilitate dermal tissuereconstruction.
OBJECTIVE: To study the histocompatibility and degradation in vivo of a new artificial material, calcium polyphosphate fiber (CPPF), and to provide some experimental basis for further study in tendon tissue engineering. METHODS: CPPF and carbon fiber (CF) as control material were implanted in symmetry part in subcutaneous layer, muscle and Achilles tendon of 20 SD rats. The day of operation, the 4th, 8th, 12th, 16th, and 20th weeks after operation, X-ray examination was performed to detect the density change of materials. Local tissue and materials were observed grossly, and pathological examination was made with HE staining 4, 8, 12, 16 weeks after operation. RESULTS: CPPF degraded completely within 16 weeks in muscle, and in 20 weeks after implantation in Achilles tendon and subcutaneous layer according to X-ray and pathological examination. No calcium phosphate crystal deposit was observed in local tissue. No obviously degradation of CF was found within 20 weeks. Local infiltration of lymphocytes and macrophagocytes around CPPF were much fewer than that of CF. CPPF combined compactly with surrounding hyperplastic tissue. CONCLUSION: CPPF degrade thoroughly from 16 to 20 weeks without sediment of crystal of calcium phosphate in vivo. CPPF has good histocompatibility and can be used as a scaffold material of tissue engineering.
Ceramiclike xenogeneic bone (CXB) was obtained from the fresh bone of pig ribs being treated by physical and chemical methods to deprive of its organic substance. The CXB possessed the same natural porous network system as that of the human. The CXB was cultured with the bone marrow stromal cells of rabit. When the marrow cells had integrated with the CXB, thus a new material was obtained. (CXB-BM), and was implanted sacro-spinal muscle of rabbit. The specimens were observed under phase microscope, light microscope and electronic scanning microscope. The results showed that: at the 2nd week after the implantation of CBX-BM composite material there began the new bone formation, and the rate of bone formation was increased with time. There was evident new bone formation after 24 weeks. The process of the new bone formation were quite similar to the composite graft of HAP red autogenous and marrow, but the former degraded faster and formed typical cancellous structure earlier. There was no new bone formation when CXB was implanted alone in the control. Both the mechanism of osteogenetic potential and its clinical application were discussed.
PURPOSE:To carry out preliminary study on immunogenicity or'the retina and provide theoretical bassis of transplant rejection of the retina. METHODS:The allogeneic whole retinal or photoreceptor layer from C57BL/6 mice wer transplanted subcutaneously into BALB/C mice for antigen exposure and delayed hypersensitivity (DH) and modified 51Cr-release assay for specific cytotoxic T lymphoeytes (CTL)were emploied. RESULTS:The allogeneic whole retinal transplantation gave rise to DH(Plt;0.05 )and increased function of CTL of which the killing rate was 33.4% in concentration of 1:90 comparing with negative group (4.8% in 1:90,Plt;0.05)and the risen function could be blocked by anti-CD8. CONCLUSION:We deduce that allogeneic whole retina has immunogenicity and should pay attention to transplant rejection postoperatively.but the photoreceptor layer seems to have no immunogenicity and may be no transplant rejection after its transplantation. （Chin J Ocul Fundus Dis,1997,13: 234-236）