ObjectiveTo explore the biocompatibility of the poly-lactide-co-glycolide (PLGA)/collagen type I scaffold with rat vaginal epithelial cells, and the feasibility of using PLGA/collagen type I as scaffold to reconstruct vagina by the tissue engineering. MethodsPLGA/collagen type I scaffold was prepared with PLGA covered polylysine and collagen type I. The vaginal epithelial cells of Sprague Dawley rat of 10-12 weeks old were cultured by enzyme digestion method. The vaginal epithelial cells of passage 2 were cultured in the leaching liquor of scaffold for 48 hours to detect its cytotoxicity by MTT. The vaginal epithelial cells were inoculated on the PLGA/collagen type I scaffold (experimental group) and PLGA scaffold (control group) to calculate the cell adhesion rate. Epithelial cells-scaffold complexes were implanted subcutaneously on the rat back. At 2, 4, and 8 weeks after implantation, the epithelial cells-scaffold complexes were harvested to observe the cell growth by HE staining and immunohistochemical analysis. The epithelial cells-scaffold complexes were transplanted to reconstruct vagina in 6 rats with vaginal defect. After 3 and 6 months, the vaginal length was measured and the appearance was observed. The neovagina tissues were harvested for histological evaluation after 6 months. ResultsThe epithelial cells grew and proliferated well in the leaching liquor of PLGA/collagen type I scaffold, and the cytotoxicity was at grade 1. The cell adhesion rate on the PLGA/collagen type I scaffold was 71.8%±9.2%, which significantly higher than that on the PLGA scaffold (63.4%±5.7%) (t=2.195, P=0.005). The epithelial cells could grow and adhere to the PLGA/collagen type I scaffolds. At 2 weeks after implanted subcutaneously, the epithelial cells grew and proliferated in the pores of scaffolds, and the fibroblasts were observed. At 4 weeks, 1-3 layers epithelium formed on the surface of scaffold. At 8 weeks, the epithelial cells increased and arranged regularly, which formed the membrane-like layer on the scaffold. The keratin expression of the epithelium was positive. At 3 months after transplantation in situ, the vaginal mucosa showed pink and lustrous epithelialization, and the majority of scaffold degraded. After 6 months, the neovagina length was 1.2 cm, without obvious stenosis; the vaginal mucosa had similar appearance and epithelial layer to normal vagina, but it had less duplicature; there were nail-like processes in the basal layer, but the number was less than that of normal vagina. The immunohistochemistry staining for keratin was positive. ConclusionThe PLGA/collagen type I scaffolds have good cytocompatibility with the epithelial cells, and can be used as the biodegradable polymer scaffold of the vaginal tissue engineering.
Objective To investigate the feasibility oftissue engineered intervertebral disc for regeneration of discs. Methods A three-dimensional porous poly(L-lactic-co-glycolic acid) (PLGA) scaffold was fabricated by temperature induced phase separation method. Human fetal disc cells were isolated and cultured in vitro. The disc cells labeledwith a PKH-26 fluorescent dye were seeded into a threedimensional porous scaffold. The proliferation of disc cells with PKH-26 fluorescent labels was assessed by using MTT uptake, laser fluorescence microscopy and SEM. Results Human fetal disc cells displayed a polygonal shape in primary monolayer culture. A regular arrangement and microtubules orientationstructure scaffold with 50-300 μm in diameter was fabricated by thermal-induced phase separation technique. MTT uptake and fluorescent microscopy examination indicated that the seeded disc cells were viable and showed proliferation activity within a porous scaffold. Conclusion The above findings support potential applications of tissue engineered disc in treatment of disc degenerative diseases.
Objective To investigate the in vivo degradable properties of new calcium phosphate cement (CPC) containing poly lactic-co-glycolic acid (PLGA) so as to lay a foundation for the future clinical application. Methods A novel CPC containing PLGA (CPC/PLGA) was prepared according to a ratio of 45% dicalcium phosphate anhydrous ∶ 45% partially crystallized calcium phosphates ∶ 10% PLGA. Thirty-two adult New Zealand rabbits (weighing 2.2-3.0 kg, male or female in half) were divided into the experimental group (n=17) and the control group (n=15). The bone defect models of the bilateral femoral condyles (4.5 mm in diameter and 1.5 cm in depth) were made by drilling hole. Defect at the right side was repaired with CPC/ PLGA in the experimental group and with CPC in the control group, while defect at the left side was not treated as blank control. The general condition of rabbits was observed after operation; the histological observation and bone histomorphometric analysis were performed at 2, 4, 8, 16, and 24 weeks; and scanning electronic microscope (SEM) observation was performed at 8 and 16 weeks after operation. Results All rabbits survived to the end of experiment. The histological observation showed: CPC/PLGA degraded gradually, and the new-born bone trabecula ingrew; bone trabeculae became rough and b; and CPC/PLGA almost biodegraded at 24 weeks in the experimental group. The CPC degradation was much slower in the control group than in the experimental group. The total bone tissue percentage was 44.9% ± 23.7% in the experimental group, and 25.7% ± 10.9% in the control group, showing significant difference between 2 groups (t=3.302, P=0.001); and the bone tissue percentage showed significant difference between 2 groups at 8, 16, and 24 weeks (P lt; 0.05). The results of SEM observation showed that the pore size was 100-300 μm at 8 weeks after operation, new-born bone trabecula grew into the pores and combined bly with residual cement in the experimental group. Conclusion Novel CPC/PLGA has good in vivo degradable properties, and it can be an ideal bone substitute in future clinical application.
Objective To observe the release pattern of the microcysts and the effect of ectopic osteogenesis of combined micromorselized bone by optimized preparation of microcysts. Methods Optimized poly-DLlactide-co-glycolide (PLGA) microcysts manufacturing method was performed with the orthogonal design, and the accumulated release amount of microcysts was calculated at 2 h, 4 h, 8 h, 12 h, 24 h, 36 h, 48 h, 60 h, 72 h, 84 h, 96 h, 120 h, 144 h, 168 h, 192 h, 216 h, 240 h and 264 h. Twentyfour Wistar rats were divided into 4 groups (n=6) and 1 cm length incision was cut in their bilateral thighs skin, forming 48 gluteus maximus muscle sackmodels. In group A,collagen was implanted to bilateral muscle sacks respectively. In group B, collagen and autologous morselized bone were implanted to bilateral muscle sacks. Ingroup C, collagen and rhBMP-2/PLGA delayed release microcysts were implanted to bilateralmuscle sacks respectively. In group D, collagen and morselized bone/rhBMP-2/PLGA delayed release microcysts were implanted to bilateral muscle sacks. Gross and histologic observations were made at 3, 4 and 5 weeks postoperatively.Results Every optimized variance had an effect on particle diameter of microcyst and its encapsulating rate. The microcyst’s surface was smooth and had a fine spheroplast, which released slowly within 11 days in vitro. In thethird week postoperatively, the graft in group A could not be touched, while the graft in all other 3 groups was still found. After 3 weeks, collagen was absorbed completely in group A, the residual collagen could be seen in groups B, C andD. After 4 weeks, collagen could be seen in group A; micromorselized bone continued to be absorbed and became smaller in group B; microsphere became smaller, osteoblasts increased in group C; micromorselized bone and microsphere continuedto be absorbed, oteoblasts and chondroblasts increased. After 5 weeks, implantsbecame small, microsphere was absorbed, osteoblasts and chondroblasts became more in groups B, C and D. Microcysts presented with white granuloshape and were packaged in tissue pieces. Histologic observation showed that the PLGA microcysts in 3 weeks and 4 weeks could be absorbed gradually as the time in vivo, if combining with morselzed bone they could produce abundant induced osteoblasts and chondroblasts. Conclusion Optimizing the preparation technology of microcysts has delayed their release during a long period in vitro. Autologous micromorselized bone can be ectopicly induced to produce large amount of osteoblasts in gluteus maximus muscle sack, where PLGA microcysts can combine organically and bring about the bone formation with less amount of growth factors.
Objective Choose polylactide-co-glycolide/hydroxyapatite (PLGA/HA) and porous phosphate calcium (PPC) as the object that we will study, compare their degradabality and choose one as a suitable scaffold for rib reconstruction. Methods All the experiments were divided into PLGA/HA group and CPC group. Degradabality experiment in exvivo: put the two scaffold which have the same size into 0.9% NaCl, keep sterile, then put the container into warm cage，get out and weigh them in 2, 4, 8, 12 and 24 weeks, compare the different speed of the two scaffold. Degradability experiment in vivo: put the two scaffold which have the same size under the skin of the rabbit, and weigh them in 2, 4, 8, 12 and 24 weeks, the tissue around the scaffold was examinzed by HE and the scaffold was examined by electron scanning microscope. Results Micro-CT and Scanning electron microscopy shows that CPC group had better structure （1101.2228±0.6184 mg/ccm vs. 1072.5523±0.7442 mg/ccm）and porosity（70.26％±0.45％ vs.72.82％±0.51％）than PLGA/HA group; The result of degradabality experiment in vitro shows that the speed of the two scaffolds was slow. It is at 24 weeks that the degradability is obvious,and the PLGA/HA group degraded a lot which was 60%. The result of degradabality experiment in vivo shows that the speed of degradabality of PLGA/HA group was faster than that is in the 0.9% Nacl, also was faster than that of CPC group which was 96%.The reponse of tissue around the PLGA/HA was more sever than that of CPC group which is in favour of the growth of cells. Conclusion As for the reconstruction of large defect of rib, CPC is more suitable than PLGA/HA.
OBJECTIVE: To explore the feasibility of reconstructing tissue engineered vessel in vitro. METHODS: Bovine endothelial cells were isolated from calf thoracic aorta by enzyme digestion methods and subcultured and purified. The endothelial cells of the 3rd to 7th passages were seeded into the inner surface of tubular scaffold material by polyglycolic acid(PGA) coated with cross-linked collagen, and cultured in vitro for 10 days using dynamic rotation culture technique. Scanning electron microscopy was used to analyse the morphological characteristics, and prostacyclin released by endothelial cells was measured by radioimmunoassay of 6-keto-prostaglandin F1 alpha. RESULTS: The VIII factor staining of cultured endothelial cells was positive. The endothelial cells adhered well on the inner surface of tubular scaffold material with confluent monolayer covering(91.2 +/- 1.5)%. The endothelialized model released prostacyclin at a rate of (4.6 +/- 0.5) micrograms/cm2.min. There was significant difference to control group (P lt; 0.05). CONCLUSION: The PGA coating with collagen is an ideal scaffold for endothelial cells, the coverage rate is increased through dynamic rotation culture technique. It will lay a good foundation for architecture of a laminated structure of tissue engineered vessel.
Objective To evaluate the feasibility of reconstructionof urothelium tissue in vivo using tissue-engineering technique. Methods The urothelium cells were obtained from young rabbit, bladder by mechanical and enzyme digested methods. After expanded in vitro, the 4th to 5th generation urothelium cells were seeded onto the surface of 8 Polylatical／glycolic acid copolymer polymer，the polymer matrix without seeding cells served as control group. A total of 8 cell-polymer scaffolds and 4 simply scaffolds were separately implanted into subcutaneous pockets of athymic mice. Theexperiment groups included cell-polymer scaffolds 4 weeks and cell-polymer scaffolds 8 weeks. The control group included simply scaffold 4 weeks and simply scaffold 8 weeks.After 4 and 8 weeks, the specimens were obtained and examined by gross inspection, histologically and immunohistochemically. Results The results of HE and Masson staining showed that the polymer were covered by urothelium cells layers and cells layers increased markly in experimental group. Immuocytochemical studies revealed that the cells were stained positively for anti-cytokeratins (AE1/AE3) in experimental group. Fiber tissue deposition were found on the surface of polymers in control group by HE and Masson staining. Immunocytochemical staining of implants showed the negative result for cytokeratins in control group. Conclusion It is feasibility that reconstruction of urothelium tissue using tissue-engineering -technique,whichprovides basic understandings for further development of the bladder and ureteral tissue engineered research.
Objective To manufacture a poly (lactic-co-glycolic acid) (PLGA) scaffold by low temperature deposition three-dimensional (3D) printing technology, prepare a PLGA/decellularized articular cartilage extracellular matrix (DACECM) cartilage tissue engineered scaffold by combining DACECM, and further investigate its physicochemical properties. Methods PLGA scaffolds were prepared by low temperature deposition 3D printing technology, and DACECM suspensions was prepared by modified physical and chemical decellularization methods. DACECM oriented scaffolds were prepared by using freeze-drying and physicochemical cross-linking techniques. PLGA/DACECM oriented scaffolds were prepared by combining DACECM slurry with PLGA scaffolds. The macroscopic and microscopic structures of the three kinds of scaffolds were observed by general observation and scanning electron microscope. The chemical composition of DACECM oriented scaffold was analyzed by histological and immunohistochemical stainings. The compression modulus of the three kinds of scaffolds were measured by biomechanical test. Three kinds of scaffolds were embedded subcutaneously in Sprague Dawley rats, and HE staining was used to observe immune response. The chondrocytes of New Zealand white rabbits were isolated and cultured, and the three kinds of cell-scaffold complexes were prepared. The growth adhesion of the cells on the scaffolds was observed by scanning electron microscope. Three kinds of scaffold extracts were cultured with L-929 cells, the cells were cultured in DMEM culture medium as control group, and cell counting kit 8 (CCK-8) was used to detect cell proliferation. Results General observation and scanning electron microscope showed that the PLGA scaffold had a smooth surface and large pores; the surface of the DACECM oriented scaffold was rough, which was a 3D structure with loose pores and interconnected; and the PLGA/DACECM oriented scaffold had a rough surface, and the large hole and the small hole were connected to each other to construct a vertical 3D structure. Histological and immunohistochemical qualitative analysis demonstrated that DACECM was completely decellularized, retaining the glycosaminoglycans and collagen typeⅡ. Biomechanical examination showed that the compression modulus of DACECM oriented scaffold was significantly lower than those of the other two scaffolds (P<0.05). There was no significant difference between PLGA scaffold and PLGA/DACECM oriented scaffold (P>0.05). Subcutaneously embedded HE staining of the three scaffolds showed that the immunological rejections of DACECM and PLGA/DACECM oriented scaffolds were significantly weaker than that of the PLGA scaffold. Scanning electron microscope observation of the cell-scaffold complex showed that chondrocytes did not obviously adhere to PLGA scaffold, and a large number of chondrocytes adhered and grew on PLGA/DACECM oriented scaffold and DACECM oriented scaffold. CCK-8 assay showed that with the extension of culture time, the number of cells cultured in the three kinds of scaffold extracts and the control group increased. There was no significant difference in the absorbance (A) value between the groups at each time point (P>0.05). Conclusion The PLGA/DACECM oriented scaffolds have no cytotoxicity, have excellent physicochemical properties, and may become a promising scaffold material of tissue engineered cartilage.
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 To culture primary parathyroid cells by mean of simulated microgravity, observe their basic morphological characteristics, study survival rate and secretory function of parathyroid cells, and explore more excellent culture mean of parathyroid cells. Methods There were 37 male Wistar rats, the body weight was 150–200 g. The rat was intraperitoneally injected with 1% pentobarbital sodium (50 mg/kg). The parathyroid glands were surgically excised and identified pathologically. The parathyroid gland cells were got and digested them with collagenase Ⅱ, which were divided into three groups: conventional culture group (simple parathyroid cells were cultured), polyglycolic acid (PGA) scaffold culture group (the parathyroid cells were cultured on the PGA scaffold), and simulated microgravity culture group (the parathyroid cells and PGA scaffolds were cultured in simulated microgravity environment). The parathyroid cells were cultured for 1, 3, 5 or 7 days in different culture conditions, then the parathyroid hormone (PTH) was measured, morphological characteristics of the parathyroid cell was observed under phase contrast microscope, survival rate of the parathyroid cells was calculated by acridine orange/propidium iodide staining. Results The parathyroid cell morphologies of most cells were well and center of part of cell mass was necrosis on day 7 in the conventional culture group. The most parathyroid cells were spreading toward the poles along the PGA cell scaffold in the longitudinal direction and the adjacent stents were connected by extracellular matrix on day 7 in the PGA scaffold culture group. The parathyroid cells cultured under the simulated microgravity were got round and formed clusters on day 7 in the simulated microgravity culture group. Compared with the other two groups on day 7, the PTH and the survival rate of the parathyroid cells were significantly higher in the simulated microgravity culture group (P<0.05). Conclusions Parathyroid cells cultured in simulated microgravity environment could maintain better morphology, survival rate is higher, and secretory function is better. Therefore, parathyroid cells cultured in simulated microgravity could be used as good donor cell for treatment of hypoparathyroidism. PGA scaffold could be used as a good carrier for culture of parathyroid cell.