ObjectiveTo review the research progress of the role of seed cells and related cytokines in angiogenesis of the vascularized tissue engineered bone. MethodsThe latest literature of tissue engineered bone angiogenesis was reviewed, including the common source of seed cells, biological characteristics, transformation mechanism, related cytokines, and signaling pathways in re-vascularization. ResultsMicrosurgery technique, genetic technique, and co-culture system of vascularized tissue engineered bone have developed to a new level. Moreover, both the induction of introduced pluripotent stem cells and vascular endothelial growth factor-angiopoietins 1 transfected mesenchymal stem cells and endothelial progenitor cells have some advantages for bone regeneration and vascularization. However, all the techniques were not used in clinical practice. ConclusionUsing techniques of genetically modified seed cells, related cytokines, and scaffolds may have bright prospects for building vascularized tissue engineered bone.
Objective To study the osteogenic effects of a new type of peptides anchored aminated-poly-D, L-lactide acid (PA/PDLLA) scaffold in repairing femoral defect in rats. Methods The PDLLA scaffolds were treated by ammonia plasma and subsequent anchor of Gly-Arg-Gly-Asp-Ser (GRGDS) peptides via amide linkage formation. Thus PA/PDLLA scaffolds were prepared. The bone marrow was harvested from the femur and tibia of 4 4-week-old Sprague Dawley (SD) rats, and bone marrow mesenchymal stem cells (BMSCs) were isolated and cultured by whole bone marrow adherence method. BMSCs-scaffold composites were prepared by seeding osteogenic-induced BMSCs at passages 3-6 on the PA/PDLLA and PDLLA scaffolds. The right femoral defects of 8 mm in length were prepared in 45 adult male SD rats (weighing, 350-500 g) and the rats were divided into 3 groups (n=15) randomly. BMSCs-PA/PDLLA (PA/PDLLA group) or BMSCs-PDLLA (PDLLA group) composites were used to repair defects respectively, while defects were not treated as blank control (blank control group). General state of the rats after operation was observed. At 4, 8, and 12 weeks after operation, general, radiological, histological, micro-CT observations and real-time fluorescent quantitative PCR were performed. Results Two rats died after operation, which was added; the other rats survived to the end of the experiment. At each time point after operation, general and radiological observations showed more quick and obvious restoration in PA/PDLLA group than in PDLLA group; no bone repair was observed in blank control group. The X-ray scores were the highest in PA/PDLLA group, higher in PDLLA group, and the lowest in blank control group; showing significant difference in multiple comparison at the other time (P lt; 0.05) except between blank control group and PDLLA group at 4 weeks (P gt; 0.05). The X-ray scores showed an increasing trend in PDLLA group and PA/PDLLA group with time (P lt; 0.05). Histological and micro-CT observations showed the best osteogenesis in PA/PDLLA group, better in PDLLA group, and worst in blank control group. Comparison between groups had significant differences (P lt; 0.05) in bone mineral density, bone volume/total volume of range of interest, trabecular number, and structure model index. Significant differences (P lt; 0.05) were found in the expression levels of osteogenesis-related genes, such as osteocalcin, alkaline phosphatase, collagen type I, bone morphogenetic protein 2, and osteopontin when compared PA/PDLLA group with the other groups by real-time fluorescent quantitative PCR analysis. Conclusion The PA/PDLLA scaffolds can accelerate the repair of femoral defects in rats.
Objective To investigate the protocols of combined culture of human placenta-derived mesenchymal stem cells (HPMSCs) and human umbilical vein endothelial cells (HUVECs) from the same and different individuals on collagen material, to provide the. Methods Under voluntary contributions, HPMSCs were isolated and purified from human full-term placenta using collagenase IV digestion and lymphocyte separation medium, and confirmed by morphology methods and flow cytometry, and then passage 2 cells were cultured under condition of osteogenic induction. HUVECs were isolated from fresh human umbilical vein by collagenase I digestion and subcultured to purification, and cells were confirmed by immunocytochemical staining of von Willebrand factor (vWF). There were 2 groups for experiment. Passage 3 osteoblastic induced HPMSCs were co-cultured with HUVECs (1 ∶ 1) from different individuals in group A and with HUVECs from the same individual in group B on collagen hydrogel. Confocal laser scanning microscope was used to observe the cellular behavior of the cell-collagen composites at 1, 3, 5, and 7 days after culturing. Results Flow cytometry showed that HPMSCs were bly positive for CD90 and CD29, but negative for CD31, CD45, and CD34. After induction, alizarin red, alkaline phosphatase, and collagenase I staining were positive. HUVECs displayed cobble-stone morphology and stained positively for endothelial cell marker vWF. The immunofluorescent staining of CD31 showed that HUVECs in the cell-collagen composite of group B had richer layers, adhered and extended faster and better in three-dimension space than that of group A. At 7 days, the class-like microvessel lengths and the network point numbers were (6.68 ± 0.35) mm/mm2 and (17.10 ± 1.10)/mm2 in group A, and were (8.11 ± 0.62) mm/mm2 and (21.30 ± 1.41)/mm2 in group B, showing significant differences between the 2 groups (t=0.894, P=0.000; t=0.732, P=0.000). Conclusion Composite implant HPMSCs and HUVECs from the same individual on collagen hydrogel is better than HPMSCs and HUVECs from different individuals in integrity and continuity of the network and angiogenesis.
Objective To observe the histological structure and cytocompatibility of novel acellular bone matrix (ACBM) and to investigate the feasibility as a scaffold for bone tissue engineering. Methods Cancellous bone columns were harvested from the density region of 18-24 months old male canine femoral head, then were dealt with high-pressure water washing, degreasing, and decellularization with Trixon X-100 and sodium deoxycholate to prepare the ACBM scaffold. The scaffolds were observed by scanning electron microscope (SEM); HE staining, Hoechst 33258 staining, and sirius red staining were used for histological analysis. Bone marrow mesenchymal stem cells (BMSCs) from canine were isolated and cultured with density gradient centrifugation; the 3rd passage BMSCs were seeded onto the scaffold. MTT test was done to assess the cytotoxicity of the scaffolds. The proliferation and differentiation of the cells on the scaffold were observed by inverted microscope, SEM, and live/dead cell staining method. Results HE staining and Hoechst 33258 staining showed that there was no cell fragments in the scaffolds; sirius red staining showed that the ACBM scaffold was stained crimson or red and yellow alternating. SEM observation revealed a three dimensional interconnected porous structure, which was the microstructure of normal cancellous bone. Cytotoxicity testing with MTT revealed no significant difference in absorbance (A) values between different extracts (25%, 50%, and 100%) and H-DMEM culture media (P gt; 0.05), indicating no cytotoxic effect of the scaffold on BMSCs. Inverted microscope, SEM, and histological analysis showed that three dimensional interconnected porous structure of the scaffold supported the proliferation and attachment of BMSCs, which secreted abundant extracellular matrices. Live/dead cell staining results of cell-scaffold composites revealed that the cells displaying green fluorescence were observed. Conclusion Novel ACBM scaffold can be used as an alternative cell-carrier for bone tissue engineering because of thoroughly decellularization, good mircostructure, non-toxicity, and good cytocompatibility.
Objective To explore the osteogenesis and angiogenesis effect of bone marrow mesenchymal stem cells (BMSCs) derived osteoblasts and endothelial cells compound with chitosan/hydroxyapatite (CS/HA) scaffold in repairing radialdefect in rats. Methods The BMSCs were isolated from Sprague Dawley rats and the 3rd generation of BMSCs were induced into osteoblasts and endothelial cells. The endothelial cells, osteoblasts, and mixed osteoblasts and endothelial cells (1 ∶ 1) were compound with CS/HA scaffold in groups A, B, and C respectively to prepare the cell-scaffold composites. The cell proliferation was detected by MTT. The rat radial segmental defect model was made and the 3 cell-scaffolds were implanted, respectively. At 4, 8, and 12 weeks after transplantation, the graft was harvested to perform HE staining and CD34 immunohistochemistry staining. The mRNA expressions of osteopontin (OPN) and osteoprotegerin (OPG) were detected by RT-PCR. Results Alkal ine phosphatase staining of osteoblasts showed that there were blue grains in cytoplasm at 7 days after osteogenic induction and the nuclei were stained red. CD34 immunocytochemical staining of the endothelial cells showed that there were brown grains in the cytoplasm at 14 days after angiogenesis induction. MTT test showed that the proliferation level of the cells in 3 groups increased with the time. HE staining showed that no obvious osteoid formation, denser microvessel, and more fibrous tissue were seen at 12 weeks in group A; homogeneous osteoid which distributed with cord or island, and many osteoblast-l ike cells were seen in groups B and C. The microvessel density was significantly higher in groups A and C than group B at 3 time points (P lt; 0.05), and in group A than in group C at 12 weeks (P lt; 0.05). The OPN and OPG mRNA expressions of group A were significantly lower than those of groups B and C at 3 time points (P lt; 0.05). In groups B and C, the OPN mRNA expressions reached peak t8 and 12 weeks, respectively, and OPG mRNA expressions reached peak at 4 weeks. Conclusion BMSCs derived steoblasts and endothelial cells (1 ∶ 1) compound with CS/HA porous scaffold can promote bone formation and vascularization in bone defect and accelerate the healing of bone defect.
Objective To compare the effect between vascularization osteogenesis and membrane guided osteogenesis in the bone repair by the tissue engineered bone with pedicled fascial flap packing autologous red bone marrow (ARBM), so as to provide a reference for the bone defect repair in cl inic. Methods The tissue engineered bone was constructed with ARBM and the osteoinductive absorbing recombinant human materials with recombinant human bone morphogenetic protein 2. Sixty New Zealand rabbits (aged 4-5 months, weighing 2.0-2.5 kg) were randomly divided into group A (n=16), group B (n=22), and group C (n=22). The complete periosteum defect model of 1.5 cm in length was prepared in right ulnar bone, then the tissue engineered bone was implanted in the bone defect area in group A, the tissue engineered bonewith free fascial flap in group B, and the tissue engineered bone with pedicled fascial flap in group C. At 4, 8, 12, and 16 weeks, the tissue of bone defect area was harvested from 4 rabbits of each group for the general, histological, and immunohistochemical staining observations; at 8, 12, and 16 weeks, 2 rabbits of groups B and C, respectively were selected to perform ink perfusion experiment by axillary artery. Results The general observation showed that the periosteum-l ike tissues formed in the fascial flap of groups B and C, chondroid tissues formed in group B, new bone formed in group C, and the fibrous and connective tissues in group A at 4 and 8 weeks; a few porosis was seen in group A, more new bone in group B, and bone stump formation in group C at 12 and 16 weeks. Histological observation showed that there were few new blood vessels and new bone trabeculae in groups A and B, while there were large amounts of new blood vessels and mature bone trabeculae in group C at 4 and 8 weeks. There were a few new blood vessels and new bone trabeculae in group A; more blood vessels, significantly increased mature trabeculae, and the medullary cavity formation in group B; and gradually decreased blood vessels, the mature bone structure formation, and the re-opened medullary cavity in group C at 12 and 16 weeks. The immunohistochemical staining observation showed that the levels of CD105, CD34, and factor VIII were higher in group C than in groups A and B at different time points.The bone morphometry analysis showed that the trabecular volume increased gradually with time in 3 groups after operation; the trabecular volume in group C was significantly more than those in groups A and B at different time points (P lt; 0.05); and there was significant difference between groups A and B (P lt; 0.05) except the volume at 4 weeks (P gt; 0.05). The vascular image analysis showed that the vascular regenerative area ratio in group C was significantly higher than those in groups A and B at different time points (P lt; 0.05). The ink perfusion experiment showed that the osteogenic zone had sparse ink area with no obvious change in group B, while the osteogenic zone had more intensive ink area and reached the peak at 8 weeks, then decreased in group C. Conclusion The tissue engineered bone with pedicled fascial flap packing ARBM has the vascularization osteogenesis effect at early stage, but the effect disappears at late stage gradually when the membrane guided osteogenesis is main.
Objective To investigate the osteogenesis effects of angiopoietin 1 (Ang-1) gene transfected bone marrow mesenchymal stem cells (BMSCs) seeded on β tricalcium phosphate (β-TCP) scaffolds (tissue engineered bone) with platelet-rich plasma (PRP). Methods BMSCs were isolated from bone marrow tissue of rabbits. The Ang-1 gene was transfected into the BMSCs at passage 2 by lentivector, which were seeded on β-TCP scaffolds with PRP (0.5 mL) after 48 hours of transfection. Bilateral radial segmental bone defects (15 mm in length) were created in 20 3-month-old New Zealand rabbits. Then the tissue engineered bone with the Ang-1 gene transfected BMSCs (experimental group) and untransfected BMSCs (control group) were implanted into the defects in the right and left radius, respectively. X-ray, histology, immunohistochemistry, and biomechanics observations were done at 2, 4, 8, and 12 weeks after operation. Results In vitro, the transfected rate was over 90% and RT-PCR showed that the Ang-1 expression were significantly increased after transfection. The X-ray films showed that some callus formed at 4 weeks, partial bony union was observed at 8 weeks, and complete union at 12 weeks in experimental group; and bone union was not observed at 12 weeks in control group. HE staining showed that capillary appeared at 8 weeks and more capillaries were observed in new bone at 12 weeks in experimental group; only a few capillaries were observed at 12 weeks in control group. At 8 and 12 weeks, the microvascular density were (50.1 ± 7.8) /mm2 and (66.1 ± 3.5) /mm2 in experimental group and were 0 and (30.3 ± 7.2)/mm2 in control group, showing significant differences between 2 groups at 12 weeks (Z= —2.107, P=0.031). Immunohistochemistry examination showed that the positive cells can be found at 8 weeks in experimental group. And the biomechanical analysis showed that maximum loads of experimental group were significantly higher than those of control group in three-point bending test and compression test at 12 weeks (P lt; 0.05). Conclusion The tissue engineered bone with PRP and Ang-1 can increase the osteogenic properties by enhancing capillary regeneration, thus it can be used to repair radial segmental bone defects of rabbit.
Objective The combined appl ication of green fluorescent protein (GFP) and confocal laser scanning microscope three-dimensional reconstruction (CLSM-3DR) were used to monitor the construction and in vivo transplantation of tissue engineered bone (TEB), to provide for technology in selection of scaffolds and three-dimensional constructional methods. Methods After bone marrow mesenchymal stem cells (BMSCs) were isolated from a 2-year-old green goat by a combination method of density gradient centrifugation and adherent culture, and the expressions of CD29, CD60L, CD45, and CD44 in BMSCs were detected by flow cytometry. Plasmid of pLEGFP-N1 was ampl ified, digested by enzymes (Hind III, BamH I, Sal I, and Bgl II), and identified. Transfection of pLEGFP-N1 into PT67 cells was performed under the help of l iposome. Positive PT67 cells were picked out with G418, and prol iferated for harvesting virus. Based on the titre of virus, after BMSCs were infected by virus containing pLEGFP-N1, GFP positive BMSCs were collected and prol iferated for seeding cells. TEB was fabricated by GFP positive BMSCs and decalcified bone matrix (DBM) and observed by CLSM-3DR for the evaluation of the distribution and prol iferation of seeding cells. After TEB was transplanted in the defect of goat femur, CLSM was used for observing the survival and distribution of GFP positive cells in the grafts. Results The isolated cells were fibroblast-l ike morphous, with the positive expression of CD29 and CD44, and negative expression of CD60L and CD45. The digested production of pLEGFP-N1 was collected for ionophoresis, whose results showed the correct fragment length (6 900 bp). The virus of pLEGFP-N1 was harvested by transfection of pLEGFP-N1 into PT67 cells and used for further infection to obtain GFP positive BMSCs. The prol iferated GFP positive BMSCs and DBM were used for fabrication of TEB. The distribution, prol iferation, and migration of BMSCs in TEB were observed by CLSM-3DR. GFP positive cells also were observed in images of TEB graft in goat femur 28 days after transplantation. Conclusion The BMSCs labeled by GFP in three-dimensional scaffold in vivo were monitored well by CLSM-3DR. It suggests a wide use potency in monitoring of three-dimensional cultured TEB.
Objective Vascular bundle and sensory nerve bundle implantation can promote the osteogenesis of tissue engineered bone. To investigate whether vascular bundle and sensory nerve bundle implantation will affect the expressions of neurokinin 1 receptor (NK1R) and vasoactive intestinal peptide type 1 receptor (VIPR1). Methods Fifty-four 5-montholdNew Zealand rabbits were selected. Autologous bone marrow was aspirated from the posterior il iac spine of rabbits, and the bone marrow mesenchymal stem cells (BMSCs) were prol iferated in vitro. At the 3rd passage, the BMSCs were cultured in the osteogenic culture medium for 7 days. The tissue engineered bone was prepared by the combined culture of these osteoblastic induced BMSCs and β tricalcium phosphate scaffold material. A 1.5 cm segmental bone defect was created at the right femur of rabbits. After the plate fixation, defects were repaired with sensory nerve bundle plus tissue engineered bone (group A, n=18), with vascular bundle plus tissue engineered bone (group B, n=18), and tissue engineered bone only (group C, n=18). X-ray examination was used to evaluate the degree of the ossification. The expression levels of NK1R and VIPR1 were measured by the immuohistochemistry analysis and the mRNA expression of NK1R and VIPR1 by real-time PCR at 4, 8, and 12 weeks after operation. Results The better osteogenesis could be observed in group A and group B than in group C at all time points. X-ray scores were significantly higher in group B than in groups A and C (P lt; 0.05) at 4 weeks, and in groups A and B than in groupC (P lt; 0.05) at 8 and 12 weeks. The mRNA expressions of NK1R and VIPR1 were highest at 8 weeks in groups A and B and gradually decreased at 12 weeks (P lt; 0.05); the expressions were higher in groups A and B than that in group C (P lt; 0.05), and in group B than group A (P lt; 0.05). Immunohistochemistry analysis showed that the expressions of NK1R and VIPR1 were highest at 8 weeks in 3 groups, and the expressions were higher in groups A and B than in group C. Conclusion Implanting vascular bundles into the tissue engineered bone can significantly improve the expression levels of NK1R and VIPR1. It is an ideal method to reconstruct composite tissue engineered bone.
Objective Construction of viable tissue engineered bone is one of the most important research fields in the cl inical appl ication of bone tissue engineering, to investigate the function of nerve factors in bone tissue engineering by celldetection in vitro and construction of neurotization tissue engineered bone in vivo. Methods Fifty-four healthy New Zealandwhite rabbits, male or female, weighing 2-3 kg, were involved in this study. Bone marrow mesenchymal stem cells (BMSCs) from the bone marrow of white rabbits were cultured. The second passage of BMSCs were treated with sensory nerve or motor nerve homogenates, using the LG-DMEM complete medium as control. The prol iferation and osteogenic differentiation of the cells were observed and tested by the MTT assay, alkal ine phosphatase (ALP) stain, and collagen type I immunocytochemistry identification. The osteogenic induced BMSCs were inoculated in β tricalcium phosphate (β-TCP) biomaterial scaffold and cultured for 72 hours, then the β-TCP loaded with seed cells was implanted in the rabbit femur with 15 mm bone and periosteum defects. Fifty-four New Zealand white rabbits were randomly divided into three groups (n=18): sensory nerve bundle (group A) or motor nerve bundle (group B) were transplanted into the side groove of β-TCP scaffold, group C was used as a control without nerve bundle transplantation. X-ray detection was performed at the 4th, 8th, and 12th weeks after operation.