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BACKGROUND: At present, the standard method for clinical treatment of bone defects is autologous bone transplantation. However, the source of autologous bone is limited and it can cause new trauma and defects. Therefore, the development of ergonomic tissue-engineered bone has become the trend of repairing bone defects. OBJECTIVE: To summarize the characteristics and manufacturing techniques of collagen/inorganic materials to construct tissue-engineered bone. METHODS: PubMed, Web of Science (January 2000–January 2020) and CNKI (2010–2020) databases were used online to retrieve the relative articles regarding the application of collagen/inorganic composite scaffold. The key words were “collagen; inorganic materials; tissue-engineered bone; bone repair; geometry of bone scaffold” in English and Chinese, respectively. RESULTS AND CONCLUSION: Applying the principle of bionics, collagen composite inorganic materials were used to construct tissue-engineered bones by simulating the composition, structure, and characteristics of natural bones, which is an important direction in the field of bone graft materials. Collagen provides the extracellular matrix effect of the scaffold material, and promotes the migration, adhesion, and proliferation of cells on the scaffold, and accelerates the degradation of the scaffold in the body, and makes the composite scaffold has good biocompatibility and osteoinductivity. Choosing a suitable manufacturing technology to change the geometry of the collagen/inorganic material scaffold, and achieving the best three-dimensional porous nanoscale structure can promote cell adhesion and proliferation, and enhance the bone regeneration capacity of collagen/inorganic material scaffolds. Simultaneously, the surface of collagen/inorganic scaffolds is modified. Stem cells, biological factors, and polymers with osteogenic or angiogenic potential were compounded onto collagen/inorganic material scaffolds, which will improve the poor mechanical properties, insufficient structural stability, and limited bone regeneration capacity of collagen/inorganic material scaffolds. This provides a good idea for the option of tissue-engineered bone graft materials.
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Objective @#To explore the feasibility of antler powder/silk fibroin/polyvinyl alcohol scaffolds as tissue engineering bone scaffolds and the relationship between their degradation performance and the healing speed of bone defects.@*Methods @# Antler powder/silk fibroin/polyvinyl alcohol scaffolds and nano hydroxyapatite/silk fibroin/polyvinyl alcohol scaffolds were prepared by 3D printing. The whole bone marrow culture method was used to prepare blood cell sheets of Altay big tail sheep’s iliac bone marrow. With observation times of 1, 2 and 3 months, the mandibular defects of 4 sheep were established. The experimental group was coated with antler powder/silk fibroin/polyvinyl alcohol scaffolds. The control group was coated with nanohydroxyapatite/silk fibroin/polyvinyl alcohol scaffolds. The negative control group was coated with gel-free sponges. According to the self-control method of the bilateral mandible defect area, scaffolds wrapped with cell membranes or gel sponges wrapped with cell membranes were implanted. At the ends of the first, second and third months after implantation, the experimental animals were killed, cone beam CT was performed, and paraffin sections were taken for HE staining to evaluate the effect of different scaffold materials on bone regeneration and scaffold degradation.@* Results@# Scanning electron microscopy showed that both groups had regular pores and good continuity, and there was no difference in pore size and porosity between the two groups (P > 0.05). The results of CBCT imaging showed that in 3 months after operation, the experimental group had significantly better repair effects on bone defects than the control group, and the degradation rate matched the bone repair rate. The bone mineral density in the center of the defect was higher than that of the control group, which was close to that of normal bone tissue. The central bone mineral density of the experimental group at each time point was higher than those of the control group and the negative control group, and the difference was statistically significant (P < 0.05). HE staining results showed that the bone cells in the experimental group were more active, with more new capillaries and bone trabeculae formed, and the scaffold material absorbed more than the control group. @*Conclusion @#The antler powder/silk fibroin/polyvinyl alcohol scaffold can promote the repair of critical bone defects. Its degradability matches its bone tissue healing rate. It is expected to become a promising scaffold material for bone tissue engineering.
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BACKGROUND: Bone tissue engineering provides a new path to treat critical-sized bone defects. However, a stable osteogenesis and osseointegration can only be insured via formation of an intact vascular network, which can achieve satisfactory therapeutic effects. Thereafter, angiogenesis is a challenge and difficulty in bone tissue engineering. OBJECTIVE: To investigate the effect of combined application of vascular endothelial growth factor (VEGF) and platelet-derived growth factor-BB (PDGF-BB) on proliferation and angiogenesis of bone marrow mesenchymal stem cells. METHODS: Bone marrow mesenchymal stem cells from Sprague-Dawley rats were cultured and isolated in vitro, and interfered with different concentrations of VEGF (20, 40, 60, 80, 100, 120 μg/L) and PDGF-BB (20, 40, 60, 80, 100, 120 μg/L) in combination or 100 μg/L VEGF, and 100 μg/L PDGF-BB alone. The optimum concentration of promoting cell proliferation was detected by cell counting kit-8 assay. The expression levels of angiopoietin-1, hypoxia-inducible factor-1α, hepatocyte growth factor and insulin-like growth factor were detected by RT-PCR at 7 and 14 days after intervention. RESULTS AND CONCLUSION: (1) After growth factors were added, the cell proliferative ability was significantly improved, and combined application revealed better effect. The optimal concentration grou was 80 μg/L VEGF+80 μg/L PDGF-BB. (2) Both VEGF and PDGF-BB could promote the mRNA expression levels of angiopoietin-1, hypoxia-inducible factor-1α, hepatocyte growth factor and insulin-like growth factor, and the effect was more obvious in combined application. (3) The mRNA expression levels of hypoxia-inducible factor-1α and hepatocyte growth factor were significantly increased with time (P < 0.05). The mRNA expression levels of angiopoietin-1 and insulin-like growth factor were significantly decreased with time (P < 0.05). (4) In vitro experimental results suggest that VEGF and PDGF-BB at the concentration of 80 μg/L can consistently promote angiogenesis, and the effect of combined application is better than that of single application.
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Objective: To investigate the heterotopic osteogenesis of tissue engineered bone using the co-culture system of vascular endothelial cells (VECs) and adipose-derived stem cells (ADSCs) as seed cells. Methods: The partially deproteinized biological bone (PDPBB) was prepared by fibronectin combined with partially deproteinized bone (PDPB). The ADSCs of 18-week-old Sprague Dawley (SD) rats and VECs of cord blood of full-term pregnant SD rats were isolated and cultured. Three kinds of tissue engineered bone were constructed in vitro: PDPBB+VECs (group A), PDPBB+ADSCs (group B), PDPBB+co-cultured cells (VECs∶ADSCs was 1∶1, group C), and PDPBB was used as control group (group D). Scanning electron microscopy was performed at 10 days after cell transplantation to observe cell adhesion on scaffolds. Forty-eight 18-week-old SD rats were randomly divided into groups A, B, C, and D, with 12 rats in each group. Four kinds of scaffolds, A, B, C, and D, were implanted into the femoral muscle bags of rats in corresponding groups. The animals were killed at 2, 4, 8, and 12 weeks after operation for gross observation, HE staining and Masson staining histological observation, and the amount of bone collagen was measured quantitatively by Masson staining section. Results: Scanning electron microscopy showed that the pores were interconnected in PDPB materials, and a large number of lamellar protein crystals on the surface of PDPBB modified by fibronection were loosely attached to the surface of the scaffold. After 10 days of co-culture PDPBB and cells, a large number of cells attached to PDPBB and piled up with each other to form cell clusters in group C. Polygonal cells and spindle cells were mixed and distributed, and some cells grew along bone trabeculae to form cell layers. Gross observation showed that the granulation tissue began to grow into the material pore at 2 weeks after operation. In group C, a large number of white cartilage-like substances were gradually produced on the surface of the material after 4 weeks, and the surface of the material was uneven. At 12 weeks, the amount of blood vessels on the surface of group A increased, and the material showed consolidation; there was a little white cartilage-like material on the surface of group B, but the pore size of the material did not decrease significantly; in group D, the pore size of the material did not decrease significantly. Histological observation showed that there was no significant difference in the amount of bone collagen between groups at 2 weeks after operation ( F=2.551, P=0.088); at 4, 8, and 12 weeks after operation, the amount of bone collagen in group C was significantly higher than that in other 3 groups, and that in group B was higher than that in group D ( P0.05). Conclusion: The ability of heterotopic osteogenesis of tissue engineered bone constructed by co-culture VECs and ADSCs was the strongest.
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Objective: To investigate the mechanism of early vascularization of the tissue engineered bone in the treatment of rabbit radial bone defect by local injection of angiopoietin 2 (Ang-2). Methods: A single 1.5 cm long radius defect model (left and right sides randomised) was constructed from 48 New Zealand white rabbits. After implantation of hydroxyapatite/collagen scaffolds in bone defects, the rabbits were randomly divided into 2 groups: control group (group A) and Ang-2 group (group B) were injected with 1 mL normal saline and 1 mL saline-soluble 400 ng/mL Ang-2 daily at the bone defect within 2 weeks after operation, respectively. Western blot was used to detect the expressions of autophagy related protein [microtubule associated protein 1 light chain 3 (LC3), Beclin-1], angiogenesis related protein [vascular endothelial growth factor (VEGF)], and autophagy degradable substrate protein (SQSTMl/p62) in callus. X-ray films examination and Lane-Sandhu X-ray scoring were performed to evaluate the bone defect repair at 4, 8, and 12 weeks after operation. The rabbits were sacrificed at 12 weeks after operation for gross observation, and the angiogenesis of bone defect was observed by HE staining. Results: Western blot assay showed that the relative expression of LC3-II/LC3-I, Beclin-1, and VEGF in group B was significantly higher than that in group A, and the relative expression of SQSTMl/p62 was significantly lower than that in group A ( P<0.05). Radiographic and gross observation of specimens showed that only a small number of callus were formed in group A, the bone defect was not repaired; more callus were formed and complete repair of bone defect was observed in group B. The Lane-Sandhu scores in group B were significantly higher than those in group A at 4, 8, and 12 weeks after operation ( P<0.05). HE staining showed that the Harvard tubes in group B were well arranged and the number of new vessels was significantly higher than that in group A ( t=-11.879, P=0.000). Conclusion: Local injection of appropriate concentration of Ang-2 may promote early vascularization and bone defect repair of rabbit tissue engineered bone by enhancing autophagy.
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Objective To investigate the impact of sphingosine kinase 1 (SPK1) modified adipose tissue-derived stromal cells(ADSC)on tissue engineered bone osteogenesis.Methods ADSC cells isolated from SD rat fat cells were divided into CON group and SPK1 group,and then the cells were respectively infected with 10 MOI CON and SPK1 lentivirus for 48 h.The infection efficiency was confirmed by using flow cytometry.Alizarin red and oil red O was used to stain the cells 14 days after ADSC infection,and osteogenic and adipogenic ability was evaluated by detecting A595nm and A490 nm.In the meantime,the activity change of alkaline phosphatase(ALP)was detected.The SD rat femoral defect model was created,and then after combining ADSC with β-TCP,the tissue engineered bone was pressed to the defect site.The repairment of bone defect was detected by X-ray in 4,6 weeks.After infection of CON and SPK1 virus,bone morphogenetic protein(BMP7)expression in ADSC of these two groups was detected.Results The infection efficiency of CON and SPK1 lentivirus was 94.4％ vs.94.9％ respectively by flow cytometry.The SPK1 protein expression level in CON group and SPK1 group was (0.73±0.10) vs.(1.29±0.17)(P＜0.05).The A value of CON and SPK1 group at 595 nm was (0.20±0.02) vs.(0.41±0.01) (P＜0.05),respectively.The A value of CON and SPK1 group at 490 nm was (0.72±0.01) vs.(0.51±0.02)(P＜0.05),respectively.The expression level of ALP in CON and SPK1 group was (1.42±-0.09) vs.(2.68±0.09) (P＜0.01),respectively.In the repairment of bone defect,high density tissue at rat bone defect was significantly larger in SPK1 group than in CON group in 4 weeks,and in 6 weeks,bone defect of SPK1 group was healed,but CON group still had defect.The expression level of BMP7 in CON and SPK1 group was (1.13±0.16) vs.(4.46±0.23)(P＜0.05),respectively,48 h after infection.Conclusion SPK1 modified ADSC has an enhanced osteogenesis ability in vitro and in vivo,which was related to the activation of BMP7.
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The repair of bone defects poses a great challenge for reconstructive surgeons. Although the development of tissue engineering has exhibited promise in replacing damaged bone, the fabrication of large constructs with functional blood vessels remains an obstacle. From the orthopedic surgeon's point of view, the generation of axially vascularized bone, which can anastomose with the recipient vessel, might be a solution to this medical problem. In this study, we aimed to prefabricate an axially vascularized bone by combining a β-TCP scaffold, arteriovenous loop (AVL), and cell sheet in a bioreactor in vivo. Twelve rabbits were randomly allocated into two groups: the experimental group (presence of AVL) and the control group (absence of AVL). The constructs were explanted at 8 weeks postoperatively. The histomorphometric results showed 42.8±5.9% of the bone area in the AVL group and 26.6±3.5% in the control group. Similarly, vessel analysis revealed the average vessel density in the AVL group (12.5±3.3) was significantly more than that in the control group (6.1±1.5, p<0.05). Our research indicated that the combination of a β-TCP scaffold, AVL and cell sheet might engineer vascularized bone. This prefabrication strategy might facilitate clinical translation of bone tissue engineering in reconstructing large bone defects.
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Rabbits , Bioreactors , Blood Vessels , Bone and Bones , Orthopedics , Surgeons , Tissue EngineeringABSTRACT
Objective Investigate the ability of autologous endothelial progenitor cells (EPCs) in promoting the neovascular-ization of tissue engineering bone in vitro and vivo .Methods Co-culture EPCs drived from autologous peripheral blood and mesen-chymal stem cells drived from bone marrow (BMSCs) at the best proportion of 1 ∶ 2 which was the largest cell proliferation rate in vitro ,osteogenesis related cytokines Osteonectin ,Osteopotin ,Collagen Type 1(Col-1) and angiogenesis related cytokine VEGF in vitro by using real-time quantitative polymerase chain reaction(PCR) ,and compared with pure EPCs and BMSCs groups at 3rd ,7th and 14th day ;the tissue engineering bone seeded with EPCs ,BMSCs and co-culture cells (EPCs ∶ BMSCs = 1 ∶ 2) were transplanted into rabbit limbs muscle ,the growing states of tissue engineering bone were observed at 2 ,4 and 8 weeks after transplantation ,at the same time the expression of CD34 ,CD105 and ZO-1 were detected with immunohistochemistry staining .Results The mRNA expression of Osteonectin ,Osteopotin ,Col-1 and VEGF were gradually increased when detected at 3rd ,7th and 14th day with real-time PCR ,and the co-culture cells group increased most obviously in the three groups in vitro at the same period time(P< 0 .01) ;The microvascularization of the engineering biological bone were observed in vivo with immunohistochemistry ,and neovasculariza-tion of co-culture cells group was also the most obvious group in three groups ,immunohistochemical showed that CD34 ,CD105 and ZO-1 was also higher than the other two groups(P< 0 .01) .Conclusion Autologous EPCs interact with BMSCs could promote vas-cularization of tissue engineering bone both in vivo and in vitro .
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Objective To investigate the effect of different pore sized hydroxyapatite for promoting bone vascularization in tissue engineering.Methods Male Wistar rats were randomly divided into three groups,named group A,B and C,which were im-planted hydroxyapatite bioceramics compositing 4 μg bone morphogenetic protein with different aperture of 200 -300,350 -450, 500-600 μm in the back subcutaneously.The size of each block was 5 mm×5 mm×1 mm in a weight about of 40.0 mg.After im-plantation,the animals were killed and the implants and the surrounding tissue were taken out at the first,second,third and forth week respectively.HE staining of histological analysis was used to detect the situation of local neovascularization.Results There was significant difference between second and third week in group A.Comparing the area of vascularization at different time points in group B and group C,there were significant difference in the comparison of intragroup (P <0.05 ).During the first week after surgery,there was only group C that had the area of vascularization.During the second and forth week after operation,the area of vascularization in group B and group C were significant higher than group A (P <0.05).The C group showed a great deal of new-born blood vessels and clear formation of bone trabeculae.Conclusion The hydroxyapatite bioceramics of 500-600 μm could better promote vascalarization of tissue engineering in bone.
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Objective To study the healing response of a tissue engineered bone of bMSCs combined rFN/CDH-BCP in a rabbit model. Methods The biomimetic surface was achieved by immobilizing rFN/CDH onto biphasic calcium phosphate ceramic ( BCP) covalently. The effect of rFN/CDH-BCP on adhesion,proliferation and differentiation were evaluated comprehensively by using cell centrifugal adhesive as-say,MTT method,SEM,Alkaline phosphatase ( ALP) activity and alizarin red staining respectively. A rabbit lumbar fusion model was estab-lished by implanting bMSCs combined rFN/CDH-BCP into intertransverse process space of L4 ~L5 ,the fusion site bone formation was ob-served by imaging means,histological techniques was used to observe the new bone formation and distribution of seed cells. Results Cell centrifugal adhesive assay indicated the adherent bMSCs on rFN/CDH-BCP associated with the ligand density,the biomimetic surface posses-ses excellent biocompatibility. The ALP activity on rFN/CDH-BCP surface was the highest among all samples on the 10th day after induction (P<0. 05). On the 21st day,alizarin red staining showed that the oval-shaped and orange-red nodules,either the number or the area,distrib-uted wider on rFN/CDH-BCP surface. The results from X plain after 3 months revealed a fuzzy gap between material and bone bed,and higher cover rate of intertransverse process space with new bone deposition on rFN/CDH-BCP surface. Conclusion Histologically,rFN/CDH-BCP exhibited as interlacing bone trabecula bridging biomaterial suface and cortical bone of transverse process continously. The bone mass was much more than the ture BCP class. The comprehensive data reveals that when loaded with MSCs,rFN/CDH-BCP demonstrates superior char-acteristics of osteoconduction and osteoinduction,and substantially enhances healing capacity in vivo.
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BACKGROUND:As a good candidate for bioresorbable bone graft, carbonate apatite monolith can be prepared by sintering procedure;however, sintering can cause carbonate loss and result in a much lower rate of biodegradation compared to the human bone, thereby influencing the formation of new bone. OBJECTIVE:To fabricate low-crystal inity carbonate apatite monolith as bone graft and test its properties. METHODS:Calcium carbonate monolith prepared by carbonation of Ca(OH) 2 monolith was treated in 1 mol/L RESULTS AND CONCLUSION:The calcium carbonate completely transformed into low-crystal inity B-type carbonate apatite after treated for 14 days. Diametral tensile strength of the final product was (10.27±1.08) MPa, which is adequate as a reconstruction material for bone defect. The carbonate content was (4.80±0.50)%, similar to that of the nature bone. The molar Ca/P was 1.63±0.01, indicating the Ca-deficient carbonate apatite is obtained. The present method al ows an easy fabrication of low-crystal inity B-type carbonate apatite block with adequate strength and without sintering process. ammonium dihydrogen phosphate solution at 60 ℃ up to 14 days. Diametral tensile strength was examined for biomechanical properties;X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscope observation and chemical analyses (carbonate, calcium and phosphate content) were also performed for physical and chemical properties.
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BACKGROUND:Adipose-derived stem cells discovered recently are a new kind of adult stem cells, and have a strong multi-differentiation capacity. However, there are rare studies concerning in vivo osteogenic capacity of adipose-derived stem cells. OBJECTIVE:To investigate the effect of adipose-derived stem cells combined with gelatin sponge on repairing bone defects. METHODS:Adipose-derived stem cells from rabbit inguinal fat pads were isolated and cultured, and then induced using an osteogenic medium containing bone morphogenetic protein 2 fol owed by injection of gelatin sponge. Radial defect models of rabbits were prepared. Compound of adipose-derived stem cel s and gelatin sponge was implanted into the lesion side, while gelatin sponge alone was implanted into the contralateral side. Rabbits were kil ed at weeks 6 and 12 after bone defect repair for X-ray examination, CT scan, and hematoxylin-eosin staining. RESULTS AND CONCLUSION:Lane-Sandhu X-ray and Lane-Sandhu histological scores after compound implantation were significantly higher than those after repair with gelatin sponge alone. It indicates that adipose-derived stem cel s combined with gelatin sponge can promote bone defect healing of rabbits, showing an obvious osteogenic capacity in vivo.
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BACKGROUND:As a bone scaffold material,β-tricalcium phosphate has good biocompatibility, osteoinductive, and biomechanical properties. OBJECTIVE:To study the effect of al ogeneic osteoblasts compounded withβ-tricalcium phosphate in repairing rabbit radial defects. METHODS:A total of 45 rabbit radial defect models were made and divided into three groups in random. Experimental group was repaired with the compound of al ogeneic osteoblasts andβ-tricalcium phosphate; control group withβ-tricalcium phosphate;and blank control group with nothing. The new bone formation of each group was observed and assessed by X-ray and histopathological analysis at weeks 4, 8, 16 after implantation for evaluation of the bone repairing effect. RESULTS AND CONCLUSION:With the repair time, the experimental group appeared to complete bone defect repair gradual y. By the end of 16 weeks, the X-ray showed that the bone cal us between the scaffold and the host was completely ossified, and bone defects were completely repaired in the experimental group. Histopathological observation showed continuous cortical bone formed in the defect area, and canal recanalization realized in the experimental group. Additional y, the repair effect in the experimental group was better than that in the control and blank control group at different time points (P<0.01). It is suggested that the al ogenic osteoblasts/β-tricalcium phosphate compound has the better effects on guiding bone regeneration and preventing from nonunion.
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BACKGROUND:Currently, limb salvage therapy has become the standard treatment of malignant bone tumors way, but improper treatments wil result in tumor recurrence, secondary infection, internal fixation or prosthesis loosening. OBJECTIVE:Based on the traditional surgical principle for metastatic bone tumors of the limbs, this study designed a user-friendly, individualized, simplistic pal iative treatment regimen from the actual conditions of patients to observe the reasonability, clinical efficacy and prognosis of bone cement fil ing combined with internal fixation in the treatment of metastatic malignant bone tumors. METHODS:Thirty-one patients with metastatic malignant bone tumors who required salvage treatment were screened from the Department of Orthopedics, the 421 Hospital of Chinese PLA, and their clinical data were retrospectively analyzed. Al the 31 patients were divided into two groups:tumor removal+internal fixation group (non-chemoradiotherapy group, n=11) treated with bone cement fil ing plus plate internal fixation (pal iative treatment);tumor removal+internal fixation+chemoradiotherapy group (chemoradiotherapy group, n=20), treated with radiotherapy before internal fixation plus plate internal fixation with limb salvage. The fol ow-up period was 4-38 months, averagely 18 months. RESULTS AND CONCLUSION:The fol ow-up results showed that in the non-chemoradiotherapy group, al the 11 patients survived, who could live independently and have good motor functions;in the chemoradiotherapy group, 17 of the 20 patients survived and the rest three patients died of tumor metastasis, their poor conditions and complications at 9 and 13 months after internal fixation. In patients undergoing tumor removal+plate internal fixation with limb salvage, the integrated scores for nerve and motor functions were increased by more than level 1. These findings confirm that a simple pal iative therapy of bone cement fil ing and internal fixation without chemoradiotherapy is better for metastatic malignant bone tumors patients who require limb salvage.
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BACKGROUND:Fol owing physicochemical treatment and high-temperature calcinations, heterogeneous biological bone becomes a ceramic-like heterologous bone forming a similar structure to the human bone that is a natural network pore structure, which is conducive to seed cel adhesion and proliferation. OBJECTIVE:To observe the feasibility of constructing tissue-engineered bone through combination of sintered bone and bone marrow mesenchymal stem cel s to repair alveolar defects. METHODS:Sheep bone marrow mesenchymal stem cel s as seed cel s were combined with the high temperature sintered bone as scaffold materials to construct tissue-engineered bone. Under general anesthesia, sheep bilateral mandibular first premolars were removed in batches, the alveolar ridge space between the distal root and mesial root of the second premolar to form a bone defect area of 5 mm×5 mm×5 mm. Twelve experimental sheep were equal y randomized into tissue-engineered bone group and sintered bone group, which were implanted with tissue-engineered bone and sintered bone, respectively, at the left surgical area of the mandible. The right surgical area was considered as blank control group. RESULTS AND CONCLUSION:After high-temperature calcinations, the sintered bone was chalk in color, exhibiting a porous structure as the natural cancel ous bone. The porosity was (66.10±1.32)%, and the pore size was between 137.44μm and 538.72μm. After 24 hours of bone marrow mesenchymal stem cel s inoculated to the sintered bone, a large number of cel s are visible adherent to the scaffold;up to day 7, extracel ular matrix was secreted and there was no clear boundary between the cel s and the matrix. X-ray films showed that the tissue-engineered bone and pure sintered bone implants were embedded in the surgical area, and there was a low-density shadow at the edge of the sintered bone. Hematoxylin-eosin staining showed bone trabecular formation at the experimental side, but no obvious bone formation at the control ed side. Tissue-engineered bone prepared by bone marrow mesenchymal stem cel s and sintered bone can better repair sheep alveolar bone defects, which is an ideal seed cel and scaffold material for smal range bone defects.
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BACKGROUND:The phenomenon of osteoinduction by biomaterials has been proven in animal experiments. OBJECTIVE:To investigate whether the ability of a biomaterial to initiate bone formation in ectopic implantation sites improves the performance of osteoinductive biomaterial as a scaffold for tissue-engineered bone. METHODS:We compared ectopic bone formation by combining autologous adipose-derived stromal cells with an osteoinductive and a nonosteoinductive biphasic calcium phosphate ceramic to create a tissue engineering construction in the muscle of dogs. Al implants were implanted in the back muscle of 10 adult dogs for 8 weeks and 12 weeks, including osteoinductive biphasic calcium phosphate ceramic+adipose-derived stromal cells (osteoinductive complex group), osteoinductive biphasic calcium phosphate ceramic (osteoinductive broup), nonosteoinductive biphasic calcium phosphate ceramic+adipose-derived stromal cells (nonosteoinductive complex group), and nonosteoinductive biphasic calcium phosphate ceramic (nonosteoinductive group). Micro-CT analysis and histomorphometry were performed to evaluate and quantify ectopic bone formation. RESULTS AND CONCLUSION:Ectopic bone formation was visible in the osteoinductive complex group and osteoinductive group, and the former group was superior to the latter one in quality of new bone (P<0.05). However, there was no ectopic bone formation in the other two groups. Micro-CT results were consistent with the histomorphological detection. These findings indicate that osteoinductive biphasic calcium phosphate ceramic, as a kind of bone tissue engineering scaffold material, has a better osteogenic capacity, while adipose-derived mesenchymal stem cells serve as seed cells to promote the ectopic bone formation.
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BACKGROUND:Silk fibroin, chitosan, and nano hydroxyapatite are natural materials, and they al have good biological activity and physical or chemical properties. As tissue engineering materials, they have been already widely used in clinic or research work, but there are some defects in the application of these three kinds of materials. OBJECTIVE:To discuss the preparation and characteristics of silk fibroin/chitosan/nano hydroxyapatite complicated scaffolds which could be used in bone tissue engineering. METHODS:Silk fibroin, chitosan, and nano hydroxyapatite were separately prepared into 2%solution, and then mixed at the ratio of 1:1:0.5, 1:1:1, 1:1:1.5 respectively. The three-dimensional complicated scaffolds were prepared by those mixed liquids through repeated freeze drying and chemical crosslinking technology. Scanning electron microscope was used to detect the pore size of the scaffolds. Porosity, water absorption rate, and hot-water loss rate were determined. Mechanical tester was used to measure the tensile and compressive modulus of dried three-dimensional scaffolds. RESULTS AND CONCLUSION:The silk fibroin/chitosan/nano hydroxyapatite complicated scaffold in the dry state had no special smel , appeared to be a stabilized solid cylinder, and exhibited clear resiliency and flexibility with a touch. With the increased content of nano hydroxyapatite, the porosity, water absorption rate and average pore size of the scaffolds appeared to be decreased, while the hot-water loss rate and compressive strength were increased. The scaffold prepared at 1:1:1 was better for bone tissue engineering, and the average pore size, water absorption rate and hot-water loss rate were 85.67 μm, (135.65±4.56)%and (22.84±1.06)%, respectively, closer to the needs of the bone tissue engineering. Uniform pores were found within the scaffold at 1:1:1, showing the network structure, developed transport among pores, and the network structure was approximately 10μm.
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BACKGROUND:Titanium has been widely used in dental implantation because of its good biocompatibility, mechanical properties and its similar elastic modulus to the bone. OBJECTIVE:To summarize three strategies for surface modification of titanium implants:physical modification, chemical modification and biochemical modification. METHODS:PubMed and CNKI databases were searched for articles published from January 2007 to February 2013, and the key words were“titanium, implant, surface modification, osseointegration”in English and Chinese, respectively. Articles which are closely related to titanium implant surface modification and osseointegration were included, and repetitive articles were removed. RESULTS AND CONCLUSION:After preliminary search, 199 articles were found. According to the inclusion criteria and exclusion criteria, 76 articles were further analyzed. Titanium implant is a bioinert material, and thus the researchers focus on surface modification to activate the titanium implant so as to possess biological function and achieve early osseointegration. Implant surface modification strategies include three perspectives:physical modification, chemical modification and biochemical modification which can shorten the period of implant therapy and achieve early osseointegration and higher binding strength. The future research trend is to combine three strategies and to further explore the molecular basis of mechanism at the interface between implant and organism cel and the tissue in order to use better surface modification technology to fulfil the early and more stable osseointegration between the implant and bone tissue.
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BACKGROUND:The form and structure of antigen-extracted xenogeneic cancel ous bone through series of physical and chemical treatment are similar to human tissue. OBJECTIVE:To detect the biocompatibility of antigen-extracted xenogeneic cancel ous bone matrix prepared by three different ways. METHODS:The antigen-extracted xenogeneic cancel ous bone scaffold materials which were prepared through physical, chemical and physical-chemical combined methods and hydroxy apatite biological ceramic materials were implanted into the dorsum subcutaneous tissue. Histological observation was done at 4, 8 and 12 weeks after surgery. The antigen-extracted xenogeneic cancel ous bone scaffold materials which were prepared through physical, chemical and physical-chemical combined methods respectively was used to culture sheep bone marrow mesenchymal stem cells for 7 days. Cel adhesion, growth, proliferation and stroma secretion were observed. RESULTS AND CONCLUSION:At 4 weeks after surgery, a strong inflammatory reaction was detected around materials in four groups. At 12 weeks, the xenogeneic bone materials prepared through physical and physical-chemical combined methods and hydroxy apatite biological ceramic materials internal pore and surrounding tissue inflammation disappeared basical y, with the presence of thimbleful inflammation cells. The material degradation was more than at 8 weeks. The xenogeneic bone materials prepared through chemical methods material internal pore and surrounding tissue inflammation stil existed, suggesting that the xenogeneic bone materials prepared through physical and physical-chemical combined methods exhibited good histocompatibility. A smal amount of orderly osteoblasts existed around hydroxy apatite biological ceramic materials and physical-chemical prepared materials, with a smal amount of bone. These suggested that there was a tendency for ectopic bone formation. The xenogeneic cancel ous bone materials prepared through physical or physical-chemical combined methods have better cytocompatibility. However, scaffold materials prepared through chemical method have poor cytocompatibility and they are not qualified for the safety standards of biological materials.
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BACKGROUND:Through a ful investigation of biodegradable scaffolds, we propose a new self-expanding degradable poly-L-lactide coated endotracheal stent based on the design, production, experimental and clinical applications of nickel titanium memory alloy stent. OBJECTIVE:To design a kind of biodegradable endotracheal stent with poly-L-lactide and hydroxyapatite, and to test its mechanical properties, biocompatibility and biodegradation capacity. METHODS:With the technology of computer aided design, the stents were prepared with poly-L-lactide (Mr RESULTS AND CONCLUSION:The average radial supporting force of the tracheal stent was 7.8 kPa, the percentage of stent surface coverage was less than 20%, the stent expansion rate was≥4%, and the stent longitudinal shortening rate was≤9%, which reached the mechanical requirements for degradable endotracheal stents. After 4-16 weeks, there was no significant inflammatory response. The decline in molecular weight changes and weight loss ratio was higher for in vivo degradation than in vitro degradation at different time (P<0.05). These findings indicate that poly-L-lactide/hydroxyapatite composite stents have good mechanical properties, biocompatibility and biodegradability. 150 000) and hydroxyapatite materials, 20 mm to 26 mm in diameter. The mechanical properties were tested using a universal testing machine. These poly-L-lactide/hydroxyapatite stents were implanted into dog models of tracheal stenosis at an appropriate size. The histopathological changes of the tracheas were observed, and biodegradation property was studied via molecular weight changes and weight loss ratio after 4, 8, 12, 16 weeks.