The effect of a fibrin-fibronectin/beta-tricalcium phosphate/recombinant human bone morphogenetic protein-2 system on bone formation in rat calvarial defects

In spite of good prospects for bone morphogenetic proteins (BMP) applications, an ideal carrier system for BMPs has not yet been identified. The purpose of this study was to evaluate the osteogenic effect of a fibrin-fibronectin sealing system (FFSS) combined with beta-tricalcium phosphate (beta-TCP) as a carrier system for recombinant human bone morphogenetic proteins (rhBMP-2) in the rat calvarial defect model. Eight-millimeter critical-size calvarial defects were created in 100 male Sprague-Dawley rats. The animals were divided into five groups of 20 animals each. The defects were treated with rhBMP-2/FFSS, rhBMP-2/FFSS/beta-TCP, FFSS and FFSS/beta-TCP carrier control or were left untreated as a sham-surgery control. Defects were evaluated by histologic and histometric parameters following a 2- and 8-week healing interval (10 animals/group/healing intervals). The FFSS/beta-TCP carrier group was significantly greater in new bone area at 2 weeks (p<0.05) and new tissue area at 2 and 8 weeks (p<0.01) relative to the FFSS carrier group. New bone and new tissue area in the rhBMP-2/FFSS/beta-TCP group were significantly greater than in the rhBMP-2/FFSS group at 8 weeks (p<0.01). On histologic observation, FFSS remnants were observed at 2 weeks, but by 8 weeks, the FFSS appeared to be completely resorbed. rhBMP-2 combined with FFSS/beta-TCP produced significantly more new bone and new tissue formation in this calvarial defect model. In conclusion, FFSS/beta-TCP may be considered as an available carrier for rhBMP-2.     

Injectable rhBMP-2-loaded chitosan hydrogel composite: osteoinduction at ectopic site and in segmental long bone defect

Carriers for bone morphogenetic protein-2 (BMP-2) used in clinical practice still suffer from limitations such as insufficient protein retention. In addition, there is a clinical need for injectable carriers. The main objective of this study was to assess bone forming ability of rhBMP-2 combined either with chitosan hydrogel (rhBMP-2/CH) or chitosan hydrogel containing β-tricalcium phosphate (β-TCP) (rhBMP-2/CH/TCP). Formulations were first compared in a rat ectopic intramuscular bone formation model, and the optimal formulation was further evaluated in healing of 15-mm critical size defect in the radius of a rabbit. Three weeks after injection ectopically formed bone was analyzed by microcomputerized tomography (micro-CT) and histology. Significantly higher (4.7-fold) mineralized bone formation was observed in the rhBMP-2/CH/TCP group compared to rhBMP-2/CH group. In a pilot study, defect in a rabbit radius treated with rhBMP-2/CH/TCP showed incomplete regeneration at 8 weeks with composite leakage from the defect, indicating the need for formulation refinement when segmental defect repair is foreseen.     

Comparative study between coral-mesenchymal stem cells-rhBMP-2 composite and auto-bone-graft in rabbit critical-sized cranial defect model

Tissue engineered bone has become a bone substitute for the treatment of bone defects in animal research. This study investigated the osteogenesis capacity of coral-MSCs-rhBMP-2 composite with the auto-bone-graft as control. Coral-MSCs-rhBMP-2 composite were fabricated by coral (as main scaffold), rhBMP-2 (as growth factor), and MSCs (cultured from iliac marrow as seed cells). Critical-sized defects (d = 15 mm) were made on forty rabbits crania and treated by different composite scaffolds: iliac autograft (n = 8), coral (n = 8), rhBMP-2/coral (n = 8), and MSCs/rhBMP-2/coral (n = 8). The defects were evaluated by gross observation, radiographic examination, histological examination, and histological fluorescence examinations after 8 and 16 weeks. The results showed that repair of bone defect was the least in coral group, and significant ingrowth of new bone formation and incorporation could be seen with 77.45% +/- 0.52% in radiopacity in MSCs/rhBMP-2/coral group, which was similar to that in iliac autograft group (84.61% +/- 0.56% in radiopacity). New bone formation in MSCs/rhBMP-2/coral group was more than that in rhBMP-2/coral group. And osteogenesis rate in MSCs/rhBMP-2/coral group (10.23 +/- 1.45 microm) was much faster than that in rhBMP-2/coral group (5.85 +/- 2.19 microm) according to histological fluorescence examination. Newly formed bone partly came from induced MSCs in composite scaffold according to bromodeoxyuridine immunohistochemical examination. These data implicated that MSCs could produce synergic effect with coral-rhBMP-2, and the tissue engineered bone of coral-MSCs-rhBMP-2 is comparable to auto-bone-graft for the repair of critical-sized bone defect.     

Mineral apposition rates provide significant information on long-term effects in BMP-induced bone regeneration

In this study, a CaP biomaterial was used as a carrier for rhBMP-2. Biomaterials were investigated in calvarial and femoral defects using a rabbit animal model, with unloaded biomaterials serving as control. Fluorochrome labels were administered at days 14 and 70. Specimens were retrieved after 12 weeks for histological analysis. When area fractions were assessed by conventional histomorphometry, no significant effect of rhBMP-2 on the amounts of regenerated bone and residual biomaterial were seen by 12 weeks. After mineral appositional rate (MAR) measurement using double labels, calculation yielded significantly higher MARs for defects at both implantation sites, when compared with surrounding bone, whether or not biomaterials were loaded with rhBMP-2. Analyzing the effect of rhBMP-2, both defect sites showed significantly higher MARs in the rhBMP-2 group. MARs of bone surrounding the defects had also been elevated significantly by rhBMP-2 at calvarial and femoral implantation sites. It is concluded that MAR measurement is suitable to identify long-term effects of rhBMP-2 on bone formation at a time when conventional histomorphometry using fractional area determination is inadequate. Also, by MAR assessment, effects of rhBMP-2 on surrounding bone can be documented.     

Osteoinductivity potential of rhBMP-2 associated with two carriers in different dosages

The objective of this study was to evaluate bone formation after application of different doses of recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with monoolein or poloxamer gels, in critical bone defects of rats. Forty-five Wistar rats were divided into nine treatment groups with five animals each: I: application of 1 μg rhBMP-2 + monoolein; II: 3 μg rhBMP-2 + monoolein; III: 7 μg rhBMP-2 + monoolein; IV: 1 μg rhBMP-2 + poloxamer; V: 3 μg rhBMP-2 + poloxamer; VI: 7 μg rhBMP-2 + poloxamer; VII: monoolein only; VIII: poloxamer only; and IX: critical bone defect only. A critical-sized defect of 6 mm diameter was produced in the left parietal bone and it was filled with gels of the above mentioned treatments. After 2 weeks, the calvarial bones were removed for histological processing. Bone formation in the groups that received poloxamer gel and rhBMP-2 was not significantly different from the control group (IX). Groups receiving monoolein and rhBMP-2 (1 and 3 μg) and those that received only the carriers (VII and VIII) had less bone formation in relation to the control. The association of rhBMP-2 to both poloxamer and monoolein did not exhibit any significant differentiation in bone formation in comparison with the control group.     

Bone regeneration in a rabbit critical-sized calvarial model using tyrosine-derived polycarbonate scaffolds

Porous three-dimensional tyrosine-derived polycarbonate (TyrPC) scaffolds with a bimodal pore distribution were fabricated to mimic bone architecture using a combination of salt-leaching and phase separation techniques. TyrPC scaffolds degraded in register with bone regeneration during the 6-week study period and compressive moduli of the scaffolds were maintained >0.5 MPa at 6 weeks of incubation in PBS at 37 °C. The TyrPC scaffolds either unsupplemented or supplemented with recombinant human bone morphogenetic protein-2 (rhBMP-2) were implanted in a rabbit calvarial critical-sized defect (CSD) model and the TyrPC scaffolds treated with rhBMP-2 or TyrPC coated with calcium phosphate scaffold alone promoted bone regeneration in a rabbit calvarial CSD at 6 weeks postimplantation. A synthetic TyrPC polymeric scaffold either without a biological supplement or with a minimal dose of rhBMP-2 induced bone regeneration comparable to a commercially available bone graft substitute in a nonrodent CSD animal model.     

大鼠股骨缺损模型中BBP增强BMP-2的骨诱导作用*

目的验证在大鼠节段性骨缺损模型中骨形态发生蛋白结合肽（BMP Binding Peptide,BBP）对于重组人骨形态发生蛋白-2（recombinent human bone morphogenetic protein-2,rhBMP-2）骨诱导作用的影响。方法 70只缺损大鼠分别分成7组,每组不同剂量的rhBMP-2＋/-1000 gBBP,4w和8w后分别摄片,动物8w后处死,股骨样本分别手工评估,采用uCT测量骨容积,随后分别采用组织学和生物力学分析。结果高剂量（10 g）rhBMP-2组术后8w可见骨愈合,骨缺损处骨完全覆盖和桥接,但低剂量（5 g和2 g）rhBMP-2组术后8w骨愈合欠佳。与单独应用rhBMP-2相比,使用低剂量的rhBMP-2复合一定量的BBP可以取得更满意的骨形成量。BBP增强rhBMP-2的骨形成活性发生于4~8w时,而在术后早期并无明显作用。单纯应用BBP仅可见骨缺损处局部的钙化,未见骨愈合。结论 BBP能显著增强rhBMP-2的骨形成活性,这种增强作用需要一定时间来产生效果;其活性发生于术后4~8w时,在术后早期并无明显作用。而且BBP本身并没有骨诱导潜力,仅仅能增强rhBMP-2的骨形成活性。BBP起到缓释作用,与rhBMP-2紧密结合后,让rhBMP-2缓慢而持久的释放。     

The effect of dose on rhBMP-2 signaling,delivered via collagen sponge,on osteoclast activation and in vivo bone resorption

While recombinant human bone morphogenetic protein (rhBMP)-2-based bone therapy presents potential osteoinductivity, it also leads concern due to transient osteoclast activation during early healing periods, ultimately limiting its clinical use. Therefore, we investigated in vivo and in vitro rhBMP-2 signaling which mediates early bone resorbing effect, depending on the dose, and attempted to inhibit this resorption phenomenon using NFAT inhibitor as a target molecule. High-dose of rhBMP-2 (20 μg/defect) enhanced osteoclast activation and the expression of bone resorption markers, compared to low dose (5 μg/defect) at one week after surgery in collagen sponge-delivered rat calvarial defect models. Interestingly, this trend was also observed in the expression of bone formation markers. In particular, rhBMP-2 upregulated RANKL expression, while it downregulated osteoprotegerin (OPG) expression, resulting in a dose-dependent increase in the ratio of RANKL to OPG. NFAT inhibitor (150 μm) treatment in vivo suppressed the high-dose effect of rhBMP-2 on both resorption and formation. In vitro results of rhBMP-2 signaling and NFAT inhibitor effects in rat mesenchymal stem cells showed similar trends as in vivo results. Microcomputer tomography-based evaluation at 4 weeks showed that combined treatment of NFAT inhibitor with 20 μg rhBMP-2 in vivo increased bone volume (BV) more than 20 μg rhBMP-2 alone, which showed little difference in BV compared to 5 μg of rhBMP-2. These results demonstrated that rhBMP-2 implantation concurrently signalized into enhanced osteoclastogenesis and osteoblastogenesis in vivo, dose-dependently. Ratio of RANKL/OPG might be an index for early bone resorbing activity of implanted rhBMP-2. A local cocktail treatment of NFAT inhibitor and high-dose rhBMP-2 might be an alternative to overcome early bone resorbing effects, thereby accelerating bone formation.     

The stimulation of healing within a rat calvarial defect by mPCL–TCP/collagen scaffolds loaded with rhBMP-2

Bone morphogenetic proteins (BMPs) have been widely investigated for their clinical use in bone repair and it is known that a suitable carrier matrix to deliver them is essential for optimal bone regeneration within a specific defect site. Fused deposited modeling (FDM) allows for the fabrication of medical grade poly ?-caprolactone/tricalcium phosphate (mPCL–TCP) scaffolds with high reproducibility and tailor designed dimensions. Here we loaded FDM fabricated mPCL–TCP/collagen scaffolds with 5 μg recombinant human (rh)BMP-2 and evaluated bone healing within a rat calvarial critical-sized defect. Using a comprehensive approach, this study assessed the newly regenerated bone employing micro-computed tomography (μCT), histology/histomorphometry, and mechanical assessments. By 15 weeks, mPCL–TCP/collagen/rhBMP-2 defects exhibited complete healing of the calvarium whereas the non-BMP-2-loaded scaffolds showed significant less bone ingrowth, as confirmed by μCT. Histomorphometry revealed significantly increased bone healing amongst the rhBMP-2 groups compared to non-treated scaffolds at 4 and 15 weeks, although the % BV/TV did not indicate complete mineralisation of the entire defect site. Hence, our study confirms that it is important to combine microCt and histomorphometry to be able to study bone regeneration comprehensively in 3D. A significant up-regulation of the osteogenic proteins, type I collagen and osteocalcin, was evident at both time points in rhBMP-2 groups. Although mineral apposition rates at 15 weeks were statistically equivalent amongst treatment groups, micro-compression and push-out strengths indicated superior bone quality at 15 weeks for defects treated with mPCL–TCP/collagen/rhBMP-2. Consistently over all modalities, the progression of healing was from empty defect < mPCL–TCP/collagen < mPCL–TCP/collagen/rhBMP-2, providing substantiating data to support the hypothesis that the release of rhBMP-2 from FDM-created mPCL–TCP/collagen scaffolds is a clinically relevant approach to repair and regenerate critically-sized craniofacial bone defects.     

Effect of adipose tissue-derived osteogenic and endothelial cells on bone allograft osteogenesis and vascularization in critical-sized calvarial defects

The use of processed bone allograft to repair large osseous defects of the skull has been limited, given that it lacks the osteogenic cellularity and intrinsic vascular supply which are essential elements for successful graft healing and, at the same time, the areas to be targeted through tissue-engineering applications. In this study, we investigated the effect of predifferentiated rat adipose tissue-derived osteoblastic cells (OBs) and endothelial cells (ECs) on calvarial bone allograft healing and vascularization using an orthotopic critical-sized calvarial defect model. For this purpose, thirty-seven 8?mm critical calvarial defects in Lewis rats were treated with bone allografts seeded with no cells, undifferentiated adipose tissue-derived stem cells (ASC), OBs, ECs, and OBs and ECs simultaneously. After 8 weeks, the bone volume and mineral density were calculated using microcomputed tomography and the microvessel formation using immunohistochemical staining and imaging software. The amount of bone within the 8?mm defect was significantly higher for the allografts treated with ECs compared with the allografts treated with OBs (p=0.05) and simultaneously with the two cell lineages (p=0.02). There were no significant differences in bone formation between the latter two groups and the control groups (allografts treated with no cells and undifferentiated ASC). There were no significant differences in bone mineral density among the groups. The amount of microvessels was significantly higher in the group treated with ECs relative to all groups (p=相似文献   

Fibroblast Growth Factor-2 Augments Recombinant Human Bone Morphogenetic Protein-2-Induced Osteoinductive Activity

The osteoinductive activity induced by recombinant human BMP-2 (rhBMP-2) blunts proportionately as the recipient ages. In order to compensate for this bluntness administration of fibroblast growth factor-2 (FGF-2) has been considered. The aim of this study was to determine whether FGF-2 administration augments osteoinductive activity caused by rhBMP-2 and to evaluate the effect of aging on bone formation induced by coadministration of rhBMP-2 and FGF-2. Sixty-four Wistar strain male rats of 8-week-old (prepubertal) and 16-week-old (postpubertal) received bone defects bilaterally in the parietal bone and the defects were filled by a polylactic acid polyglycolic acid copolymer/gelatin sponge (PGS) impregnated with rhBMP-2 plus 0 ng, 25 ng, and 250 ng FGF-2 (n=10 in each). At 2 weeks after grafting, the new bone volume seemed to be larger in the rhBMP-2+FGF-2 groups than in the rhBMP-2 alone group. At 4 weeks, the new bone formation was linked to the adjacent original bone. In the prepubertal rats, all newly formed bone was similarly calcified. In the postpubertal rats, only the rhBMP-2+25 ng FGF-2 group showed this higher degree of calcification. At 2 weeks, alkaline phosphatase (ALP) activity in the rhBMP-2+25 ng FGF-2 group was significantly (p<0.05) larger than that in the rhBMP-2 group in both prepubertal and postpubertal rats. This result shows that low-dose administration of FGF-2 enhanced the degree of calcification and ALP activity in the rhBMP-2 grafting site especially in the postpubertal rats. Therefore, FGF-2 would be a candidate to compensate for the reduction of osteoinductive activity of rhBMP-2 with aging.     

Whole-body vibration and resistance exercise prevent long-term hindlimb unloading-induced bone loss: independent and interactive effects

Skeletal unloading induced by disuse or immobilization causes a decrease in bone mass and strength. We investigated the relationship between whole-body vibration (WBV) and resistance exercise (RE) in preventing bone loss induced by 8-week hindlimb unloading in young male rats. Sixty male Wistar rats were assigned randomly to 6 groups: age-matched control group (CON, n?=?10), hindlimb unloading group (HU, n?=?10), hindlimb unloading?+?standing group (HU?+?ST, n?=?10), hindlimb unloading?+?WBV group (HU?+?WBV, n?=?10), hindlimb unloading?+?RE group (HU?+?RE, n?=?10) and hindlimb unloading?+?WBV?+?RE group (HU?+?WBV?+?RE, n?=?10). After 8-week hindlimb unloading, micro-CT scanning and three-point bending test were performed in the femur. Sera were collected for analysis of bone formation and resorption markers. Compared with HU group, WBV, RE and the combination of WBV and RE (WBV?+?RE) significantly improved (P??0.05). WBV had no effects on biomechanical properties of the femur diaphysis (P?>?0.05). RE and WBV?+?RE significantly increased maximum load and cross-sectional moment of inertia of the femur diaphysis in hindlimb unloading rats (P?相似文献   

中空羟基磷灰石复合rhBMP-2修复骨缺损过程的再血管化研究

目的　探讨和观察中空羟基磷灰石复合rhBMP-2在骨缺损修复过程的再血管化。  方法　将48只成年的新西兰雄性大白兔制作成桡骨骨缺损模型,随机分3组,各组分别植入以下材料：中空HA/ rhBMP-2复合人工骨、单纯中空HA人工骨、单纯rhBMP-2。植入后于4、8、12、16周分别注射99mTc-MDP进行放射性核素骨显像并监测骨缺损修复过程中再血管化情况,同时进行大体、X线、组织学观察。  结果　术后各时间段,中空HA/ rhBMP-2复合人工骨组在X线及放射性核素聚集强度明显高于单纯中空HA人工骨组(P<0.05) ,表现为成骨代谢活跃及早期的再血管化能力。  结论　中空HA/ rhBMP-2复合人工骨具有良好的骨缺损修复能力,成骨活性持久,再血管化能力强,有望成为一种理想的骨缺损修复材料。     

Preparation of beta-tricalcium phosphate microsphere-hyaluronic acid-based powder gel composite as a carrier for rhBMP-2 injection and evaluation using long bone segmental defect model

The specific objective of this study was to evaluate whether rhBMP-2-loaded bio-scaffolds can be used as effective rhBMP-2 carriers in the implantation of bone defect sites or poor bone quality in host bone. The rhBMP-2 release pattern test showed slow results in both groups, and a 1:9 ratio composition with a high water-absorption rate was selected for in vivo study. All animals euthanized after 9 weeks. The new bone formation and bone quantity and quality of fibular samples were examined. The results showed that the rhBMP-2 powder gel composite improved the new bone formation in the cortical bone and the marrow space. The length of new bone formation ratio of the rhBMP-2 loaded composite group was significantly higher than the powder gel group. The composite of powder gel seems to be a nice carrier, and slow release of rhBMP-2 can promote new bone formation in a segmental cortical bone defect after implantation.     

Ectopic bone formation associated with recombinant human bone morphogenetic proteins-2 using absorbable collagen sponge and beta tricalcium phosphate as carriers

The ectopic bone formation of recombinant human bone morphogenetic protein-2(rhBMP-2) was evaluated using absorbable collagen sponges (ACS) and beta tricalcium phosphate (beta-TCP) as carriers in a rat subcutaneous assay model. Subcutaneous pockets were created on the back of rats. The pockets were implanted with rhBMP-2/ACS, rhBMP-2/beta-TCP, ACS alone, and beta-TCP alone. The rats were sacrificed at 2 or 8 weeks for histological and immunohistochemical evaluation. At 2 weeks, bone formation was evident in both the rhBMP-2/ACS and rhBMP-2/beta-TCP sites. At 8 weeks, the quantity of the new bone with a more advanced stage of remodeling had increased further in the rhBMP-2/beta-TCP sites. However, the newly formed bone observed at 2 weeks was not found in the rhBMP-2/ACS sites. On immunohistochemical observation, osteopontin staining was observed on both the rhBMP-2/ACS (2 weeks) and rhBMP-2/beta-TCP (2 and 8 weeks) sites. Osteocalcin was not detected in any of the samples. The lack of space-providing capacity of ACS may be one of the major factors responsible for its failure to maintain the newly induced bone. Therefore, a carrier for BMPs should provide space for bone formation and maturation during the more advanced healing stages.     

Evaluation of bone regeneration at critical-sized calvarial defect by DBM/AM composite

This study investigated the bone-regenerative potential of a demineralized bone and acellular matrix (DBM/AM) composite (AlloCraft DBM) in comparison with autologous bone using an in vivo model. Critical-sized calvarial defects (5 mm) were created in athymic rats. The defects were grafted with either the DBM/AM composite or the acellular human dermal matrix (AM), and compared with the defects filled with autologous bone (positive control) and the empty defect (negative control). Histological and radiographic assessments were carried out at 4 and 8 weeks after surgery to determine the biological healing, the amount and type of new bone formation and the percentage of new bone filled in the critical defects. At 4 weeks, DBM/AM composite group had the highest percentage of the defect filled with new bone (84%), which was significantly greater than autologous bone (62%), AM (41%), and untreated control (32%) groups. At 8 weeks, the DBM/AM continued to have the highest percentage of the defect filled with new bone (91%). The autologous bone group increased the percentage of bone fill to 83%. The defects either filled with AM or left untreated still had less of the defect filled with new bone, 57% and 33%, respectively. The total healing of defects grafted with DBM/AM was comparable with autologous bone group at 8 weeks. The results demonstrated that the DBM/AM composite promoted new bone formation more rapidly than autologous bone at calvarial defect in athymic rats. The study supports that DBM/AM is a potential substitute of autologous bone for bone repair.     

Long-term stability of bone tissues induced by an osteoinductive biomaterial, recombinant human bone morphogenetic protein-2 and a biodegradable carrier

The long-term stability of bone tissues induced by recombinant human bone morphogenetic protein-2 (rhBMP-2) and poly[L-lactide-co-glycolide] copolymer-coated gelatin sponge (PGS) was examined. In 16 dogs, 2.5 cm unilateral bone defects were created in the left tibial diaphyses. Tibia was fixed with metal plate, and PGS impregnated with (0.4 mg/cm(3)) or without rhBMP-2 was implanted into 15 or one defects, respectively. The metal plates of rhBMP-2-treated limbs were removed 16 weeks after the implantation. The bilateral tibiae of five animals each of the rhBMP-2-treated group were harvested at 32, 52 or 104 weeks, and served for biomechanical testing and histology. Although the defect that received PGS alone resulted in nonunion at 16 weeks, all defects treated with rhBMP-2 achieved radiographic bony union by 8 weeks. Biomechanical properties of the regenerated bones restored to the levels of intact tibiae at 32 weeks, but torsional stiffness was significantly higher. No statistical significances were detected in all parameters between regenerated and intact tibiae at 104 weeks. No radiographic and histological findings suggesting enhanced resorption to the regenerated bones were observed. These results suggest the long-term stability of the bone tissues induced by rhBMP-2, and the usefulness of rhBMP-2-impregnated PGS as a biomaterial for long bone defect filling.     

重组人骨形成蛋白-2-珊瑚人工骨复合物在拔牙窝牙槽骨修复中的作用

目的:探讨重组人骨形成蛋白-2与珊瑚人工骨复合物(复合骨 )在拔牙窝修复中的作用。方法:拔除 12只成年狗两侧上颌第二及第三切牙,并去除牙槽窝之间的牙槽间隔,一侧随即植入复合骨,对侧植入珊瑚人工骨(珊瑚骨 )作为对照。并于植入后 4、8、12周取材,采用组织学观察、图像分析和 [⁹⁹Tc^m]-MDP核素骨显像等方法比较两种植入材料在牙槽窝中的骨修复能力。结果:复合骨植入牙槽骨后,材料被逐渐降解吸收,新骨不断生成,12周后,植入材料完全被成熟的骨组织取代;图像分析结果显示不同时间复合骨组新骨形成的比值显著高于珊瑚骨组(P <0.05 );4和 8周复合骨组核素浓聚程度高于珊瑚骨组,12周两组核素浓聚程度差异不明显。结论:复合骨在牙槽骨缺损中的骨修复能力和修复效果明显优于珊瑚骨.     

Conditioned media from mesenchymal stem cells enhanced bone regeneration in rat calvarial bone defects

Tissue engineering has recently become available as a treatment procedure for bone augmentation. However, this procedure has several problems, such as high capital investment and expensive cell culture, complicated safety and quality management issues regarding cell handling, and patient problems with the invasive procedure of cell collection. Moreover, it was reported that stem cells secrete many growth factors and chemokines during their cultivation, which could affect cellular characteristics and behavior. This study investigated the effect of stem-cell-cultured conditioned media on bone regeneration. Cultured conditioned media from human bone marrow-derived mesenchymal stem cells (MSC-CM) enhanced the migration, proliferation, and expression of osteogenic marker genes, such as osteocalcin and Runx2, of rat MSCs (rMSCs) in vitro. MSC-CM includes cytokines such as insulin-like growth factor-1 and vascular endothelial growth factor. In vivo, a prepared bone defect of a rat calvarial model was implanted in five different rat groups using one of the following graft materials: human MSCs/agarose (MSCs), MSC-CM/agarose (MSC-CM), Dulbecco's modified Eagle's medium without serum [DMEM(-)]/agarose [DMEM(-)], PBS/agarose (PBS), and defect only (Defect). After 4 and 8 weeks, implant sections were evaluated using microcomputed tomography (micro-CT) and histological analysis. Micro-CT analysis indicated that the MSC-CM group had a greater area of newly regenerated bone compared with the other groups (p<0.05) and histological analysis at 8 weeks indicated that the newly regenerated bone bridge almost covered the defect. Interestingly, the effects of MSC-CM were stronger than those of the MSC group. In vivo imaging and immunohistochemical staining of transgenic rats expressing green fluorescent protein also showed that migration of rMSCs to the bone defect in the MSC-CM group was greater than in the other groups. These results demonstrated that MSC-CM can regenerate bone through mobilization of endogenous stem cells. The use of stem-cell-cultured conditioned media for bone regeneration is a unique concept that utilizes paracrine factors of stem cells without cell transplantation.     

Bone formation in calvarial defects of Sprague-Dawley rats by transplantation of calcium phosphate glass

The purpose of this study was to investigate the bone-regenerative effect of calcium phosphate glass in vivo. We prepared amorphous calcium phosphate glass powder having a mean particle size of 400 microm in the system CaO-CaF2-P2O5-MgO-ZnO. Calvarial critical-sized defects (8 mm) were created in 60 male Sprague-Dawley rats. The animals were divided into an experimental group and control group of 30 animals each. Each defect was filled with a constant weight of 0.5 g calcium phosphate glass powder mixed with saline. As a control, the defect was left empty. The rats were sacrificed 2, 4, or 8 weeks postsurgery, and the results evaluated using radiodensitometric and histological studies; they were also examined histomorphometrically. When the calcium phosphate glass powders with 400-microm particles were grafted, the defects were nearly completely filled with new-formed bone in a clean healing condition after 8 weeks. It was observed that the prepared calcium phosphate glass enhanced new bone formation in the calvarial defect of Sprague-Dawley rats and could be expected to have potential for use as a hard tissue regeneration material.