Mechanical properties of alginate hydrogels with different concentrations and their effects on the proliferation chondrocytes in vitro / 生物医学工程学杂志

The mechanical properties of natural and synthetic extracellular matrices affect cellular processes and regulate tissue formation. In order to explore the optimal environment for chondrocytes growth in vitro, we investigated the relationship between the mechanical properties of the alginate beads and the ability of chondrocyte proliferation in this study. We measured the compressive properties of alginate with different concentrations by INSTRON 3365,and found that compressive moduli significantly increased with increasing alginate concentration. The rabbit chondrocytes were encapsulated in 1%, 2% and 3% (w/v) alginate beads at high (1 x 10(7)/ml) density. After 4 week's culturing, all the three groups resulted in the limited proliferation of the chondrocytes and the formation of cell clusters resembling cartilaginous tissues. Chondrocytes proliferation was more rapid on lower concentrate gels (1%, 2%) than on the higher concentrate gels (3%). These results suggested that the mechanical properties of scaffold architecture had certain effect on chondrocytes proliferation.

Role of activating transcription factor 2 in the growth of mandible condyle chondrocytes / 实用口腔医学杂志

Objective: To study the role of activating transcription factor 2 (ATF-2) in the growth of mandibular condyle cartilage. Methods: Primary chondrocytes of condyle were cultured. Expression plasmid of ATF-2 and plasmid bcl-2 promoter were transfected into chondrocytes. Luciferase assay and Western blot were used. Results: The absence of ATF-2 in mandibular condyle chondrocytes resulted in a decline in bcl-2 promoter activity, reduction in bcl-2 protein level. Conclusion: The results strongly imply that ATF-2 is required for adequate bcl-2 expression, and play a significant role in controlling growth plate chondrocyte progression.

The preparation of a new hydroxyapatite and the study on its cytocompatibility / 生物医学工程学杂志

The cuttlebones, harvested from cuttles, undergo the chemical reaction in high temperature and high pressure for a certain time. The products are qualitatively analysed, and spacial structure observation and cytocompatibility are tested. The results show that the chemical component of the cuttlebone is CaCO3 and the crystal type is aragonite. Cuttlebones undergo a hydro-thermal reaction, and thus transform into hydroxyapatite-that is, the cuttlebone-transformed hydroxyapatite(CBHA). The CBHA materials have the interconnected microporous network structures. Under the high magnification, CBHAs appear to have many micro-spheres, thus construct a new self-assembled nano-material system. The marrow stromal osteoblasts can adhere to and proliferate well on the surface of the CBHAs. These results show that CBHAs have good biocompatibility. Therefore, it can be a potential candidate scaffold for bone tissue engineering.

Experimental study on the chondrogenesis potentiality of marrow stromal cell under the induction of transforming growth factor-beta / 华西口腔医学杂志

<p><b>OBJECTIVE</b>Seed cell study is an essential area in the research of tissue engineering. To evaluate the potentiality of marrow stromal cell(MSCs) as seed cell in the regeneration of tissue engineered cartilage, formation of cartilage nodules by culture expanded MSCs pellets under the induction of TGF-beta was investigated.</p><p><b>METHODS</b>MSCs were cultured and expanded in vitro. Cell pellets containing 1 x 10(6) MSCs were obtained by centrifuging MSCs solution at 1,000 r/min in 5 ml centrifugation tube. Pellets were exposed to cell culture media containing 20 ng/ml TGF-beta for 7 days and then cultured for another 7 and 21 days. The nodules were moved out of the tube and cartilage formation was observed by stereomicroscope, light microscope and electronic microscope.</p><p><b>RESULTS</b>10 days after exposure to TGF-beta, pellets contracted and formed small and round nodules on the bottom of the tubes. The nodules grew bigger slowly and reached maximal diameter of 1.8 mm in 28 days. The surface of the nodules was smooth and bright white. Histological examination showed that extra cellular matrix formed in 14 days and in some areas cells situated in lacuna. In 28 days' specimens, a lot of cells situated in lacuna could be observed and the histological appearance looked much similar to cartilage. Electronic microscope observation demonstrated that in 28 days' specimens a large amount of collagen fiber existed.</p><p><b>CONCLUSION</b>Under the induction of TGF-beta, MSCs could differentiate into chondrogenesis cell and form cartilaginous nodules in vitro. This indicated that MSCs could be the potential seed cells in the regeneration of cartilage employing method of tissue engineering.</p>

Experimental studies on cranial defect repair with marrow stromal osteoblast-cancellous bone matrix compound artificial bone / 中华整形外科杂志

<p><b>OBJECTIVE</b>To investigate the feasibility of using marrow stromal osteoblast-cancellous bone matrix compound artificial bone (MCCAB) as tissue-engineered bone, the osteogenesis of MCCAB in the cranial defect was observed in the experiment.</p><p><b>METHODS</b>The in vitro cultivated and induced marrow stromal cells of adult New Zealand rabbits were seeded into the alginate-cancellous bone matrix to form MCCAB. The MCCAB was then implanted into the cranial defect for 4 to 8 weeks. The cancellous bone matrix (CBM) alone or the marrow stromal osteoblasts (MSOs) alone was implanted as the control. The effectiveness of bone formation was assessed by histological and roentgenographic analysis.</p><p><b>RESULTS</b>The osteogenesis of MCCAB was better than CBM or MSOs and superior to the blank group.</p><p><b>CONCLUSION</b>MCCAB can effectively repair cranial defect. It could be used clinically to restore large bone defects.</p>

Experimental study on subcutaneous bone formation by marrow stromal osteoblast-cancellous bone matrix compound artificial bone / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the feasibility of using marrow stromal osteoblast (MSO) as bone derived cell and using cancellous bone matrix (CBM) as scaffold for bone tissue engineering, the subcutaneous osteogenesis of MSO-CBM compound artificial bone (MCCAB) was observed in the experiment.</p><p><b>METHODS</b>The marrow stromal cells of adult New Zealand rabbits cultivated and induced in vitro were used to form MCCAB by mixing, seeding and solidifying methods assisted by alginate. The MCCABs were auto-transplanted subcutaneously into the rabbits for 4 to 8 weeks. The alginate-cancellous bone matrix composites or the cancellous bone matrix alone were implanted as control. The effectiveness of bone formation was assessed by means of roentgenography, histology and computerized histomorphometry.</p><p><b>RESULTS</b>The osteogenesis of MCCABs was better than that of the alginate-cancellous bone matrix composites and of the cancellous bone matrixes. In the MCCABs, both intramembranous and cartilaginous osteogeneses were seen but the former was obvious. In the control, only slight cartilaginous osteogeneses were seen.</p><p><b>CONCLUSIONS</b>The osteogeneses of the MCCABs constructed by using tissue engineering method were obvious when transplanted subcutaneously. The MSO and CBM can be used as good bone-derived cell and scaffold material respectively for tissue-engineered bone construction.</p>

Fabrication of tissue engineered bone by seeding osteoblasts into titanium coral scaffolds / 实用口腔医学杂志

砄bjective:To fabricate bone tissue that has similar structural and mechanical characters with normal bone.Methods: Titanium meshes were molded into the shape of column in the length of 12 mm and in the diameter of 8 mm. The column was filled with natural coral granduls.4?10 7 marrow derived osteoblasts in 200 ?l cell culture medium were seeded into each of five scaffolds and incubated in vitro for 2 d to ensure that cells adhere well on the scaffolds. Then the scaffolds were implanted subcutaneously into the back of nude mice. Two months after implantation, the animals were sacrificed and the implanted materials were investigated by gross specimen inspection, X ray examination and histological observation. Results:2 months after in vivo incubation, the newly formed tissue was red and had the gross appearance of bone, and kept the original shape of column. Titanium mesh situated in the surface area. X ray examination showed that large amount of new bone formed in the scaffolds, there was no space between new bone and titanium mesh. Most of coral granduls had been absorbed. Histological observation demonstrated that in the surface area, new bone integrated well with titanium mesh and was enforced by titanium mesh(like cortical bone), and in the middle area large amount of lamellar bone formed.Conclusion: Newly formed bone in this experiment has similar structural with normal cortical bone.

Tissue engineering of bone and cartilage composite / 实用口腔医学杂志

砄bjective: To fabricate tissue engineered bone cartilage composite. Method: Rabbit marrow stem cells (MSCs) were in vitro cultured, expanded and induced to differeciate to osteoblasts. Chondrocytes were obtained by collagenase type Ⅱ digestion of rabbit ear cartilage. Osteoblasts and chondrocytes were co seeded into different part of natural coral scaffold, and then implanted subcutaneously into the back of nude mice. Two months after implantation,the specimens were harvested and bone cartilage composites formation was observed by gross inspection and histologic observation. Results: The newly formed tissue was composed of two parts. One part was glisteringly white and another part was dark red. There was an obvious boundary between the two parts. Microscopic observation revealed successful restoration of bone cartilage composite. Conclusion:Bone cartilage composite can be prepared by co deeding of osteoblasts and chondrocytes into natural coral scaffold.

Fabrication of trachea cartilage ring by tissue engineering / 实用口腔医学杂志

砄bjective: To study the feasibility of fabrication of trachea cartilage ring by tissue engineering.Methods : PGA non woven mesh was put into the mold of trachea cartilage ring and enforced with polylactic acid. Rabbit chondrocytes were harvested by collagenase type Ⅱdigestion of ear cartilage and seeded into PGA scaffold in the density of 5?10 7/ml.The cell polymer complexes were incubated in vitro for 1 week and then implanted subcutaniously into the back of nude mice. The formation of trachea cartilage ring was observed by gross inspection and histological examination 2 months after implantation. Results: New cartilage tissue in the shape of trachea ring was found 2 months after implantation. The specimens showed the appearance of glisteringly white with good flexibility. Histological examination demonstrated that newly restored tissue was constituted of cartilage. Conclusion: It may be an efficient method to fabricate trachea cartilage ring by seeding chondrocytes in PGA scaffold.

Histological observation of mandibular advancement in goat using tooth-borne distraction osteogenesis device / 实用口腔医学杂志

Objective:To observe the histological character of distraction osteogenesis(DO) in the mandible of goat using an intraoral tooth-supported distraction device. Methods:8 goats (7-9 months of age) were divided into 4 groups with 2 goats per group. After a bilateral mandibular corticectomy between the second and third premolars, self-produced intraoral tooth-supported distraction devices were cemented. 5 days after operation,the distraction devices were begun to be activated 0.25 mm every 12 hours to advance the anterior segment 8 mm in 16 days. The animals of 32 days group were injected with tetracycline fluorescence labeing at 10 ml/kg once perweek from the beginning of DO.The animals were sacrificed on day 8,16,32 and 48 separately post activation, and tetracycline fluorescence labeling,HE staining and Mallory's 3-color staining were performed. Results:Tetracycline fluorescence labeling showed that there was green-yellow fluorescence labeling new bone within the distraction gap; HE and Mallory's trichrome staining showed that new bone gradually formed from bilateral sides, gradually blending and remodeling. The fiber bundles and newly formed trabeculas and various cells in early phrases showed to be orientation-directed along the axis of distraction force. Conclusion: New bone can be formed and regenerated along the axis of distraction force within the distraction gap.

Stretch-induced proliferation of cultured periodontal ligament fibroblasts / 实用口腔医学杂志

Objective: To observe the proliferation of periodontal ligament fibroblasts(PDLFs) under mechanical stretching. Methods: PDLFs were stretched by 6 cycles/min(5 seconds stretching and 5 seconds relaxing) with 12% stretching force through self-produced cultured cell loading system. At experimental time point 24,48 and 96 hours, the cells were counted and flow cytometry was employed to observe the proliferation of PDLFs. Results: 48 h and 96 h after stretch treatment the cells in experimental groups were significantly more than those in control groups respectively (P

Repair of bone defect with chitin/rhBMP2/collagen complex / 实用口腔医学杂志

Objective: To investigate the feasibility of chitin as bone substitute material and carrier of rhBMP2.Methods: Porous chitin and chitin/rhBMP2/collagen complex were implanted into calvarial defects in 8 rabbits. Bone repairing ability was assessed by radiographic and histological observation. 2 rabbits without implantation were served as controls. Results: Chitin had certain bone conductive ability. When combined with rhBMP2,a complex possessing both bone conductive activity and bone inductive activity was produced. The complex had greater bone repairing ability than chitin alone. Conclusion: Chitin may be used as a bone substitute material and carrier of BMP. But its mechanical strength and surface activity should be improved.

A preliminary study of injectable tissue-engineered bone / 实用口腔医学杂志

Objective: To develop injectable tissue-engineered bone. Methods: Bone marrow cells isolated from lilac bone of New Zealand rabbits were cultured and induced to differentiate Into osteoblasts. The osteoblasts were mixed with 20 g/L alginate sodium solution to generate osteoblasts/alginate composite with final cellular density of 5 ? 10 6/ml. Calcium chloride was used as cross-linking agent. The osteoblasts/alginate composite was injected into the dorsal subcutaneous tissue of nude mice. The injected material with surounding tissue were examined with X-ray and histopathologic technique. Results: Four and eight weeks after injection, the hard knobbles were easily palpated under the dorsal skin of the animals. On X-ray photograph the knobbles showed calcified tissue image. In histological analysis, new bone formation was observed in the osteoblasts/alginate composite. The osteogenesis was in association with regenerated hematopoietic bone marrow. Conclusion: New bone tissue can be created through the injection of alginate sodium mixed with marrow stromal osteoblasts.

Preparation of tissue engineered bone graft loading titanium dental implant / 实用口腔医学杂志

Objective: To prepare tissue engieered bone graft loading titanium dental implant. Methods: Titanium dental implant (3 mm in diameter) was inserted into porous natural coral column((5 mm in diameter). Bone marrow derived osteoblasts were cultured and expanded in vitro. Cells were induced by recombinant human bone morphogenetic protein-2 for three days and then harvested and seeded into porous coral and onto dental implant at the density of 2 ?108/ml. Four cell-coral-implant complexs were incubated in vitro for 2 days and then implanted subcutaniously into nude mice. New bone formationre and new bone integration with dental implant were evaluated by gross inspection, X-ray examination and hitologic observation 1 and 2 months after implantation. Results: By gross observation, specimen of 1 month was red and white. X-ray examination showed that there was little radiodense shadow around the dental implant. Specimen of 2 months was red and had the gross appearance of bone. Dental implant could be observed situating in the newly formed bone graft. X-ray examination showed that coral scaffold was absorbed completely. Large amount of X -ray blocking shadow could be observed around the dental implant. Histologic examination showed that bone-like tissue formed in the pores and on the surface of natural coral and in some area new bone could be observed integrating with implant in 1 month specimen. In 2 months specimen, large amount of new bone formed around the implant and integrated well with the implant. Conclusions: Tissue engineered bone graft may integrate well with titatium dental implant.

Tissue engeneered bone in the shape of human TMJ condyle with marrow stem cells and porous natural coral / 实用口腔医学杂志

Objective: To prepare tissue engeneered bone in the shape of human TMJ condyle. Methods: Rabbit marrow stem cells (MSCs) were in vitro cultured and induced by rhBMP2.107 Cells were seeded into each piece of natural porous coral (NC) in the shape and in the size of 4 -year-old-child mandibular condyle. After two days in vitro incubation, six cell-coral complexes were implanted subcautanrously into the back of nude mice. Two months after operation, bone formation was observed by gross inspection,X-ray examination,scanning electronic microscope observation and histological observation. Results: New bone grafts in the shape of human mandibular condyle were successfully restored two months after implantation in all the samples. X-ray examination showed large amount of X-ray blocking shadow. NC was partially absorbed. New bone formation could be observed by electronic microscope observation and hostological observation on the surface and in the pores of NC. Conclusion: It is an effective method to fabricate bone graft in specific shape by seeding osteogenesis cells into natural coral in the wanted shape.

STUDY ON BONE TISSUE ENGINEERING / 解放军医学杂志

To investigate the feasibility of using coral and other materials as scaffolds for bone tissue engineering, coral, coral hydroxyapatite(CHA), cancellous bone matrix and other natural biomaterials served as culture scaffolds of osteoblasts were manufactured. The results showed, in addition to PLA, PGA, PLGA and other synthetic polymers, some natural biomaterials are also ideal scaffolds materials for bone tissue engineering.