Objective To provide the seed cells for bone tissue engineering, to establ ish immortal ized human bone marrow mesenchymal stem cells (MSCxj) and to investigate the ectopic osteogenesis of MSCxj. Methods MSCxjs of the 35thand 128th generations were maintained and harvested when the cell density reached 2 109. Then, these cells were co-cultured with heterogeneous bone scaffold in groups A (the 35th generation, n=12) and group B (the 128th generation, n=12); heterogeneous bone alone was used in group C (n=12). The cell prol iferation was observed by scanning electron microscopy (SEM) after 48 hours and 18 days of osteogenic induction culture. The complex was implanted subcutaneouly through a 3-mm-incision at both sides of the back in 18 nude mice. Tetracycl ine label ing was performed before the animals were sacrificed. Tetracycl ine fluorescence staining, HE staining, ponceau staining, and immunohistochemistry staining for osteocalcin were performed at 4, 8, and 12 weeks after transplantation; the morphologic quantitative analysis was made. Results After 48 hours, SEM showed that MSCxjs adhered to heterogeneous bone and grew well; after 18 days, a large number of new filamentous extracellular matrix and small granules were found to cover the cells. The results of tetracycl ine fluorescence staining, HE staining, and ponceau staining in groups A and B showed that the osteogenesis was not obvious at 4 weeks after transplantation; osteoid matrix deposition was noted around and in theheterogeneous bone at 8 weeks; and osteogenesis was increased at 12 weeks. There was no significant difference in bone formation between groups A and B. Osteogenesis was not observed in group C. The osteocalcin expressions were positive in groups A and B. The bone ingrow percentages of groups A and B were 5.64% ± 2.68% and 4.92% ± 2.95% at 8 weeks, and 13.94% ± 2.21% and 14.34% ± 3.46% at 12 weeks, showing significant differences between 8 weeks and 12 weeks at the same group (P lt; 0.05) and no significant difference between groups A and B at the same time (P gt; 0.05). Conclusion MSCxj has favorable abil ities of ectopic osteogenesis and can be appl ied as seeded cells in bone tissue engineering.
OBJECTIVE: To establish the animal models of mandibular distraction osteogenesis in rabbits and study its osteogenetic mechanism. METHODS: The right mandibles just anterior to the first molars of 12 rabbits were performed osteotomies, and the mandibles were positioned with distractors. The left mandibles were control group without operation. After 1 week, the distractors were stretched 0.9 mm every day for 10 days progressively. One day, 2, 4, 8 weeks after distraction, the mandibles were studied with gross measurement, X-ray, and histological examination. RESULTS: The right mandible were lengthened 8.3 mm on average without bone nonunion and deformity healing. It was observed that the gaps between the distracted bone edges were first occupied by fibrous tissue. Two weeks after distraction, it was found that the gaps were bridged by callus in X-ray, the new bone and the normal bone could not be differentiated clearly after 8 weeks. In histological sections, there were collagen bundles in early distraction, then those collagen bundles were calcificated and become trabeculaes. No Cartilage was found during distraction. CONCLUSION: It suggests that the rabbit mandible can be lengthened by distraction osteogenesis, and the new bone is formed by intramembranous ossification.
Objective To investigate the mode and influential factor of newbone formation following distraction osteogenesis in mandibular lengthening. Methods Corticotomy was performed on bilateral mandibles in twelve adult male goats. A custommade distractor was used to lengthen the mandible at a rate of 1mm/day for 10 days (total 10 mm elongation). Four goats were sampled respectivelyat 2, 4 and 8 weeks after completion of distraction. The lengthening mandibles were examined by roentgenography and histology. Results Newly formed callus was observed in the distraction gap after mandibular lengthening. The new bone exhibited intramembranous ossification generally, but cartilage islands could be found in the specimen that diastractor loosed. Conclusion The above findings indicate that the mode of new bone formation in mandibular lengthening following distraction osteogenesis appears to be intramembranous ossification and that endochondral ossification takes place in case distractor has loosened.
Objective To study the mechanism of ectopic osteogenesis of nacre/Polylactic acid (N/P) artificial bone combined with allogenic osteoblasts, and to explore the possibility as a scaffold material of bone tissue engineering. Methods The allogenic- osteoblasts seeded onto N/P artificial bone were co-cultured in vivo 1 week.The N/P artificial bone with allogenic osteoblasts were implanted subcutaneously into the left back sites of the New Zealand white rabbits in the experimental group and the simple N/P artificial bone into the right ones in the control group. The complexes were harvested and examined by gross observation, histologic analysis and immunohistochemical investigation 2, 4 and 8 weeks after implantation respectively.Results In experimental group, the osteoid formed after 4 weeks, and the mature bone tissue withbone medullary cavities formed after 8 weeks; but in control group there was nonew bone formation instead of abundant fibrous tissue after 4 weeks, and more fibrous tissue after 8 weeks.Conclusion N/P artificial bone can be used as an optical scaffold material of bone tissue engineering.
By using Urist s method four types of BMG from the long bones of the rabbit、 pig、sheep、 and human being were prepared. Each of them was implanted into the pectoralis and thigh muscles in 25 adult rats, respectiely. Two-eight weeks after implantation, the unoreaction and inductive osteogensis potential in the tissues were observed under mieroscope. The result showed that aBMG had inductive osteogenesis potential. However, rejection in varying digree existed around aBMG. It was important to further decrease the antingenicity digree exised around a BMG . and enhance its osteogennic potential before the possibility of its clinical application.
Objective To examine the mRNA expression of activin A(ACT A) and follistatin(FS) during mandibular lengthening and to elucidate the regulating pattern of during mandibular distractionosteogenesis.Methods Skeletally mature-white New Zealand rabbits were established right mandibular distraction osteogenesis models and the mandibles were lengthened 7 days after osteomy. Atthe end of latency period and the end of distraction period, 10,20, 30, 40 and60 days after fixation, the regenerating tissue of animals’ lengthened mandibles and that of the other side normal mandibles were harvested to extract RNA andto analyse ACT A, FS mRNA by RT-PCR.Results The expression of ACT A mRNA was not detectable in normal bone tissue and ACT A mRNA began to express at the end of latency period. The expression of ACT AmRNA increased gradually along with the beginning of distraction and reached the peak on the 10th and 20th days of distraction which was 5.04 and 4.98 times as much as that of the end of latency period, respectively. The trend of expression of FS mRNA during mandibular distraction osteogenesis was the same as expression of ACT A mRNA. Conclusion ACT A/FS play an important role during rabbit mandibular distraction osteogenesis.
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.
Mesenchymal stem cells (MSCs) have the property of osteogenic induction. As a result, using the property of MSCs to treat the fractures and bone defects has become a new treatment modality with the development of cell and tissue engineering technology. Caveolae is a flask-shaped membrane microdomain in cell membrane, which composed primarily of cholesterol, sphingolipids and proteins. Caveolin-1 is one of the main protein component. Caveolae is the integrator of cell signals, and many signal molecules gather here to bind with caveolin-1 protein to regulate cell proliferation, differentiation and other life activities. This paper presents a review about Caveolae/Caveolin-1 biologic effects on cell differentiation of MSCs.
OBJECTIVE This experimental study was aim to investigate the osteogenesis of ceramic-like xenogeneic bone (CXB) combining with bone marrow (BM). METHODS The CXB combining BM was implanted into the sacrospinalis muscle of rabbits, and CXB implanted alone was used as control. Eighteen Japanese rabbits with long ear were used. The size of CXB was 5 mm x 5 mm x 5 mm, and the implanted materials were taken out at 2, 4, 8, 12, 16 and 24 weeks after implantation. The histological and histochemical characteristics were investigated. RESULTS There existed cartilage and new bone in the groups of CXB combining BM in 2 weeks. Later, be cartilage turned out to the bone and in eight weeks the medullary cavity appeared. However, as the time went on, new bone formation increased and typical osteogenesis could be found. While in the groups of CXB alone, no formation of new bone or cartilage was found. CONCLUSION The implantation of CXB combined with BM could result in new bone formation in the way of osteoconduation, osteoinduction, and providing, osteoblasts or chondroblasts. It could be an ideal bone substitute, and its clinical use in future seemed very hopeful.
Objective To review the research progress on the role of Schwann cells in regulating bone regeneration. MethodsThe domestic and foreign literature about the behavior of Schwann cells related to bone regeneration, multiple tissue repair ability, nutritional effects of their neurotrophic factor network, and their application in bone tissue engineering was extensively reviewed. ResultsAs a critical part of the peripheral nervous system, Schwann cells regulate the expression level of various neurotrophic factors and growth factors through the paracrine effect, and participates in the tissue regeneration and differentiation process of non-neural tissues such as blood vessels and bone, reflecting the nutritional effect of neural-vascular-bone integration. ConclusionTaking full advantage of the multipotent differentiation ability of Schwann cells in nerve, blood vessel, and bone tissue regeneration may provide novel insights for clinical application of tissue engineered bone.