转碱性成纤维细胞生长因子基因组织工程骨修复兔骨缺损

背景:生物活性玻璃是一类具有良好生物活性及骨修复特性的生物医用材料,将其与血、脱钙骨基质或与骨形态发生蛋白等混合来促进成骨形成,增加强度,骨愈合更接近于天然骨结构。目的:观察生物活性玻璃结合转碱性成纤维细胞生长因子基因骨髓间充质干细胞构建组织工程骨修复兔骨缺损的效果。方法:以生物活性玻璃作为转碱性成纤维细胞生长因子基因骨髓间充质干细胞的可吸附载体,体外构建组织工程骨,将其植入兔桡骨中段 10 mm 骨缺损处,以自体骨移植组、生物活性玻璃/骨髓间充质干细胞组和空白组作为对照,术后 2,4,8,12 周进行影像学、病理组织切片、生物力学测试,观察各组骨缺损修复效果。结果与结论:以生物活性玻璃作为转碱性成纤维细胞生长因子基因骨髓间充质干细胞的可吸附载体,体外构建的组织工程骨植入兔桡骨骨缺损的成骨效应、骨愈合后的抗扭转强度明显优于其他各组(P < 0.01)。说明生物活性玻璃结合转碱性成纤维细胞生长因子基因骨髓间充质干细胞构建的组织工程骨可用于骨缺损修复,优于自体骨移植。     

转碱性成纤维细胞生长因子基因组织工程骨修复兔骨缺损

背景：生物活性玻璃是一类具有良好生物活性及骨修复特性的生物医用材料,将其与血、脱钙骨基质或与骨形态发生蛋白等混合来促进成骨形成,增加强度,骨愈合更接近于天然骨结构。目的：观察生物活性玻璃结合转碱性成纤维细胞生长因子基因骨髓间充质干细胞构建组织工程骨修复兔骨缺损的效果。方法：以生物活性玻璃作为转碱性成纤维细胞生长因子基因骨髓间充质干细胞的可吸附载体,体外构建组织工程骨,将其植入兔桡骨中段 10 mm 骨缺损处,以自体骨移植组、生物活性玻璃/骨髓间充质干细胞组和空白组作为对照,术后 2,4,8,12 周进行影像学、病理组织切片、生物力学测试,观察各组骨缺损修复效果。结果与结论：以生物活性玻璃作为转碱性成纤维细胞生长因子基因骨髓间充质干细胞的可吸附载体,体外构建的组织工程骨植入兔桡骨骨缺损的成骨效应、骨愈合后的抗扭转强度明显优于其他各组（P 〈 0.01）。说明生物活性玻璃结合转碱性成纤维细胞生长因子基因骨髓间充质干细胞构建的组织工程骨可用于骨缺损修复,优于自体骨移植。     

Comparing the osteogenic potential of bone marrow and tendon‐derived stromal cells to repair a critical‐sized defect in the rat femur

Despite significant advancements in bone tissue‐engineering applications, the clinical impact of bone marrow stromal cells (BMSCs) for the treatment of large osseous defects remains limited. Therefore, other cell sources are under investigation for their osteogenic potential to repair bone. In this study, tendon‐derived stromal cells (TDSCs) were evaluated in comparison to BMSCs to support the functional repair of a 5 mm critical‐sized, segmental defect in the rat femur. Analysis of the trilineage differentiation capacity of TDSCs and BMSCs cultured on collagen sponges revealed impaired osteogenic differentiation and mineral deposition of TDSCs in vitro, whereas chondrogenic and adipogenic differentiation was evident for both cell types. Radiographic assessment demonstrated that neither cell type significantly improved the healing rate of a challenging 5 mm segmental femoral defect. Transplanted TDSCs and BMSCs both led to the formation of only small amounts of bone in the defect area, and histological evaluation revealed non‐mineralized, collagen‐rich scar tissue to be present within the defect area. Newly formed lamellar bone was restricted to the defect margins, resulting in closure of the medullary cavity. Interestingly, in comparison to BMSCs, significantly more TDSC‐derived cells were present at the osteotomy gap up to 8 weeks after transplantation and were also found to be located within newly formed lamellar bone, suggesting their capacity to directly contribute to de novo bone formation. To our knowledge, this is the first study investigating the in vivo capacity of TDSCs to regenerate a critical‐sized defect in the rat femur. Copyright © 2015 John Wiley & Sons, Ltd.     

Octacalcium phosphate collagen composite facilitates bone regeneration of large mandibular bone defect in humans

Recently it was reported that the implantation of octacalcium phosphate (OCP) and collagen composite (OCP–collagen) was effective at promoting bone healing in small bone defects after cystectomy in humans. In addition, OCP–collagen promoted bone regeneration in a critical‐sized bone defect of a rodent or canine model. In this study, OCP–collagen was implanted into a human mandibular bone defect with a longer axis of approximately 40 mm, which was diagnosed as a residual cyst with apical periodontitis. The amount of OCP–collagen implanted was about five times greater than the amounts implanted in previous clinical cases. Postoperative wound healing was satisfactory and no infection or allergic reactions occurred. The OCP–collagen‐treated lesion was gradually filled with radio‐opaque figures, and the alveolar region occupied the whole of the bone defect 12 months after implantation. This study suggests that OCP–collagen could be a useful bone substitute material for repairing large bone defects in humans that might not heal spontaneously. Copyright © 2015 John Wiley & Sons, Ltd.     

同种异体脱钙骨基质复合自体骨髓基质干细胞修复兔关节软骨缺损

背景:脱钙骨基质具有良好的生物相容性,是临床常用的骨缺损修复材料.骨髓基质干细胞具有向骨及软骨细胞分化的潜能,适合骨软骨缺损修复.目的:观察同种异体脱钙骨基质复合自体骨髓基质干细胞修复兔关节软骨缺损的效果.方法:27只兔均建立骨软骨缺损模型,造模后随机分为3组:复合材料组钻孔植入复合自体骨髓基质干细胞培养8 d的脱钙骨基质块,单纯脱钙骨基质组钻孔单纯植入脱钙骨基质块,模型对照组钻孔后不植入任何材料.取材后对修复组织进行大体观察、组织学观察及Ⅱ型胶原免疫组织化学染色鉴定,并参照Wakitani评分标准对修复组织进行评分.结果与结论:植入后12周,复合材料组修复组织呈透明软骨样,表面光滑平坦,与周围软骨及软骨下骨结合良好;单纯脱钙骨基质组有部分软骨样修复;而模型对照组仅有少量纤维性修复.植入后12周,复合材料组、单纯脱钙骨基质组修复组织Ⅱ型胶原免疫组化染色均呈阳性,修复细胞表达Ⅱ型胶原,为软骨细胞;模型对照组呈阴性表达.植入后4,8,12周,复合材料组修复效果评分均显著优于单纯脱钙骨基质组、模型对照组(P<0.01).说明自体骨髓基质干细胞复合同种异体脱钙骨基质支架材料修复兔全层关节软骨缺损的效果良好.     

脂肪基质细胞构建组织工程骨修复下颌骨缺损的实验研究

背景：以往实验认为,只有经过成骨诱导后的脂肪基质细胞才能作为骨组织工程的种子细胞。然而成骨诱导周期过程复杂,延长了细胞体外培养时间和花费。目的：探讨未经过成骨诱导的犬脂肪基质细胞作为种子细胞,利用组织工程技术修复犬下颌骨缺损的可行性。方法：取12个月龄犬背部皮下脂肪,经胶原酶消化法获得单个核细胞,将培养的第3代细胞与双相磷酸钙陶瓷形成支架复合物。在犬下颌骨两侧制备长20mm、高10mm的箱状缺损,拔除缺损区牙齿,分别植入细胞支架复合物和单纯双相磷酸钙陶瓷支架,不进行干预的区域作为空白对照。植入后4周及8周经组织学检测骨缺损修复情况。结果与结论：支架植入后4周,部分支架材料降解,缺损区形成新生骨,双相磷酸钙陶瓷组成骨量明显少于细胞支架复合物组,形成少量新骨及部分新生血管。8周时,两组形成更多的新骨,广泛分布于骨缺损区域,但双相磷酸钙陶瓷组仍明显少于细胞支架复合物组,差异有显著性意义（P〈0.01）。提示脂肪基质细胞复合双相磷酸钙陶瓷可在体内成骨,不经过体外成骨诱导的脂肪基质细胞作为种子细胞,利用组织工程技术可修复下颌骨缺损。     

Accelerating bone defects healing in calvarial defect model using 3D cultured bone marrow‐derived mesenchymal stem cells on demineralized bone particle scaffold

Bone defects are usually difficult to be regenerated due to pathological states or the size of the injury. Researchers are focusing on tissue engineering approaches in order to drive the regenerative events, using stem cells to regenerate bone. The purpose of this study is to evaluate the osteogenic differentiation of bone marrow‐derived mesenchymal stem cells (BMSCs) on biologically derived Gallus gallus domesticus‐derived demineralized bone particle (GDD) sponge. The sponges were prepared by freeze‐drying method using 1, 2, and 3 wt% GDD and cross‐linked with glutaraldehyde. The GDD sponge was characterized using scanning electron microscopy, compressive strength, porosity, and Fourier transform infrared. The potential bioactivity of the sponge was evaluated by osteogenic differentiation of BMSCs using 3(4, dimethylthiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide assay and quantifying alkaline phosphatase (ALP) activity. in vivo experiments were evaluated through a micro‐computerized tomography (μ ‐CT) and histological assays. The analysis confirmed that an increase in the concentration of the GDD in the sponge leads to a higher bone formation and deposition in rat calvarial defects. Histological assay results were in line with μ ‐CT. The results reported in this study demonstrated the potential application of GDD sponges as osteoinductor in bone tissue engineering in pathological or nonunion bone defects.     

Novel standardized massive bone defect model in rats employing an internal eight‐hole stainless steel plate for bone tissue engineering

Massive bone defects are a challenge in orthopaedic research. Defective regeneration leads to bone atrophy, non‐union of bone, and physical morbidity. Large animals are important models, however, production costs are high, nursing is complex, and evaluation methods are limited. A suitable laboratory animal model is required to explore the underlying molecular mechanism and cellular process of bone tissue engineering. We designed a stainless steel plate with 8 holes; the middle 2 holes were used as a guide to create a standardized critical size defect in the femur of anaesthetized rats. The plate was fixed to the bone using 6 screws, serving as an inner fixed bracket to secure a tricalcium phosphate implant seeded with green fluorescent protein‐positive rat bone marrow mesenchymal stem cells within the defect. In some animals, we also grafted a vessel bundle into the lateral side of the implant, to promote vascularized bone tissue engineering. X‐ray, microcomputed tomography, and histological analyses demonstrated the stainless steel plate resulted in a stable large segmental defect model in the rat femur. Vascularization significantly increased bone formation and implant degradation. Moreover, survival and expansion of green fluorescent protein‐positive seeded cells could be clearly monitored in vivo at 1, 4, and 8 weeks postoperation via fluorescent microscopy. This standardized large segmental defect model in a small animal may help to advance the study of bone tissue engineering. Furthermore, availability of antibodies and genetically modified rats could help to dissect the precise cellular and molecular mechanisms of bone repair.     

The effect of fresh bone marrow cells on reconstruction of mouse calvarial defect combined with calvarial osteoprogenitor cells and collagen–apatite scaffold

Fresh bone marrow cells have already exhibited its advantages as osteogenic donor cells, but the combination between fresh bone marrow cells and other donor cells utilized for bone healing has not been fully explored. To highlight the impact of fresh bone marrow cells on scaffold‐based bone regeneration, single or a combination of calvarial osteoprogenitor cells (OPCs) and bone marrow cells (BMCs) were used as donor cells combined with collagen–apatite scaffold for calvarial defect healing. The host and donor contributions to bone formation were assessed using histological and GFP imaging analysis. Although the amount of new bone formed by different cell sources did not show significant differences, the origin of the bone formation in the defects mainly depended on the types of donor cells employed: when only calvarial OPCs were used as donor cells, a donor‐derived bone healing instead of host‐derived bone ingrowth was observed; when only fresh BMCs were loaded, the host bone could grow into the defect along the lamellar structure of the scaffolds, but the amount of new bone formed was significantly lower than the defect loaded with calvarial OPCs only. The combination of calvarial OPCs and fresh BMCs had similar amount of new bone formation as the group loaded with calvarial osteoprogenitors alone, but did not induce any host‐derived bone formation. These results provide compelling evidence of the importance of fresh BMCs to induce host–implant integration in bone tissue engineering. Copyright © 2012 John Wiley & Sons, Ltd.     

异种骨和人工骨修复骨肿瘤性骨缺损

背景：自体植骨是修复骨肿瘤刮除后骨缺损最理想的材料和方法,但存在增加手术创伤,取骨部位的后遗症如感染和疼痛及自体骨的取量有限等缺点。目的：分析硫酸钙人工骨和异种骨修复良性骨肿瘤刮除后骨缺损的临床疗效。方法：选择26例良性骨肿瘤患者,其中骨巨细胞瘤8例,内生软骨瘤5例,纤维组织细胞瘤4例,骨纤维异样增殖症3例,非骨化性纤维瘤2例,骨囊肿2例,动脉瘤样骨囊肿和软骨母细胞瘤各1例。12例采用单一硫酸钙骨粒填充肿瘤切除后的骨缺损,6例采用单一异种骨条填充肿瘤切除后的骨缺损,8例采用硫酸钙骨粒＋异种骨条填充肿瘤切除后的骨缺损。治疗后1周内、3个月、1年拍X射线片检查,了解植骨愈合情况。结果与结论：治疗后随访36-72个月,发现硫酸钙骨粒的降解发生较早,一般治疗后1个月就开始出现骨粒降解,3个月大部分已降解完毕并有骨替代发生,1年骨修复塑型良好;异种骨条3个月后降解并有骨替代发生,植骨充填物边缘模糊,6个月后骨缺损及充填物之间边界变模糊,有融合现象,1年骨缺损内密度均匀,骨小梁形成明显,骨修复良好;骨粒＋骨条混合植骨者介于单纯硫酸钙骨粒和单纯异种骨条之间,出现骨粒部分先降解先修复、骨条部分后降解后修复,一般术后1年达到骨性愈合。说明硫酸钙人工骨和异种骨在骨肿瘤性骨缺损修复应用中的效果良好,在良性骨肿瘤刮除后植骨可以替代自体骨植骨。     

Bone marrow mesenchymal stem cells,platelet‐rich plasma and nanohydroxyapatite–type I collagen beads were integral parts of biomimetic bone substitutes for bone regeneration

Platelet rich plasma (PRP), which includes many growth factors, can activate osteoid production, collagen synthesis and cell proliferation. Nanohydroxyapatite‐type I collagen beads (CIB), which mimetic natural bone components, are not only flexible fillers for bone defect but also encourage osteogenesis. Bone marrow mesenchymal stem cells (BMSCs) are often used as an abundant cell source for tissue engineering. We used a rabbit model to combine PRP, CIB and BMSCs (CIB+PRP+BMSC) into a bone‐like substitute to study its impact on bone regeneration, when compared to defect alone, PRP, CIB+PRP, and PRP+BMSC. CIB+PRP upregulated more alkaline phosphatase (ALP) activity in BMSCs than PRP alone at 4 weeks postoperation. CIB+PRP+BMSC and PRP+BMSC did not differ significantly in DNA content, total collagen content, and ALP activity at 8 weeks. In histological assay, both CIB+PRP+BMSC and PRP+BMSC showed more bone regeneration at 4 and 8 weeks. Higher trabecular bone volume in tissue volume (BV/TV) (31.15±2.67% and 36.93±1.01%), fractal dimension (FD) (2.30±0.18 and 2.65±0.02) and lower trabecular separation (Tb.Sp) (2.30±0.18 and 1.35±0.16) of CIB+PRP+BMSC than of other groups at 4 and 8 weeks, and approach to of bone tissue (BV/TV=24.35±2.13%; FD=2.65±0.06; Tb.Sp=4.19±0.95). CIB+PRP+BMSC significantly enhanced new bone formation at 4 week. Therefore, nanohydroxyapatite‐type I collagen beads combined with PRP and BMSCs produced a bone substitute with efficiently improved bone regeneration that shows promise to repair bone defects. Copyright © 2012 John Wiley & Sons, Ltd.     

聚左旋乳酸/壳聚糖纳米纤维三维多孔支架复合骨髓间充质干细胞修复兔骨缺损

背景：骨髓间充质干细胞具有向多种间质细胞谱系分化的能力,且支架材料的性能对骨缺损的修复有重要影响。目的：观察聚左旋乳酸/壳聚糖纳米纤维三维多孔支架复合骨髓间充质干细胞治疗骨缺损。方法：对骨缺损模型兔分别采用空白植入、髂后上棘自体松质骨移植、聚左旋乳酸/壳聚糖纳米纤维多孔支架移植和复合了骨髓间充质干细胞的聚左旋乳酸/壳聚糖纳米纤维多孔支架移植修复缺损部位。结果与结论：至移植12周,移植复合了骨髓间充质干细胞的聚左旋乳酸/壳聚糖纳米纤维多孔支架的实验兔的缺损处有骨组织生成,支架材料降解,已完成缺损修复,其修复情况接近松质骨组;髂后上棘自体松质骨移植的实验兔的缺损修复完好,新形成的骨组织较规则;只植入聚左旋乳酸/壳聚糖纳米纤维多孔支架的实验兔有少量骨组织形成,材料部分降解;空白植入的实验兔缺损处无新生骨组织生成,主要由纤维结缔组织填充。说明新型的生物支架材料聚左旋乳酸/壳聚糖纳米纤维三维多孔支架与来源于新西兰大白兔的骨髓间充质干细胞复合培养后,植入同种异体兔股骨髁缺损处,使骨缺损的修复速度加快,表现为较好的体内诱导成骨的作用。     

BMP‐2‐transduced human bone marrow stem cells enhance neo‐bone formation in a rat critical‐sized femur defect

Synthetic graft materials are considered as possible substitutes for cancellous bone, but lack osteogenic and osteoinductive properties. In this study, we investigated how composite scaffolds of βTCP containing osteogenic human bone marrow mesenchymal stem cells (hBMSCs) and osteoinductive bone morphogenetic protein‐2 (BMP‐2) influenced the process of fracture healing. hBMSCs were loaded into βTCP scaffolds 24 h before implantation in a rat critical‐sized bone defect. hBMSCs were either stimulated with rhBMP‐2 or transduced with BMP‐2 by gene transfer. The effect of both protein stimulation and gene transfer was compared for osteogenic outcome. X‐rays were conducted at weeks 0, 1, 3, 6, 9 and 12 post‐operatively. In addition, bone‐labelling fluorochromes were applied at 0, 3, 6 and 9 weeks. Histological analysis was performed for the amount of callus tissue and cartilage formation. At 6 weeks, the critical‐sized defect in 33% of the rats treated with the Ad‐BMP‐2‐transduced hBMSCs/βTCP scaffolds was radiographically bridged. In contrast, in only 10% of the rats treated with rhBMP2/hBMSCs, 12 weeks post‐treatment, the bone defect was closed in all treated rats of the Ad‐BMP‐2 group except for one. Histology showed significantly higher amounts of callus formation in both Ad‐BMP‐2‐ and rhBMP‐2‐treated rats. The amount of neocartilage was less pronounced in both BMP‐2‐related groups. In summary, scaffolds with BMP‐2‐transduced hBMSCs performed better than those with the rhBMP2/hBMSCs protein. These results suggest that combinations of osteoconductive biomaterials with genetically modified MSCs capable of secreting osteoinductive proteins may represent a promising alternative for bone regeneration. Copyright © 2015 John Wiley & Sons, Ltd.     

骨诱导性磷酸钙陶瓷为支架的组织工程骨修复狗下颌骨箱状缺损

背景:应用不外加生长因子或细胞而具有骨诱导性的生物材料,在非骨部位构建骨移植物,即体内组织工程骨,其在修复箱状及节段性骨缺损方面,具有更可行的前景.目的:采用骨诱导性钙磷陶瓷材料构建体内组织工程化类骨移植物,探索其应用于修复实验动物下颌骨箱状骨缺损的可行性.方法:以骨诱导性磷酸钙陶瓷材料为支架植入狗肌肉内构建体内组织工程骨,同期在狗自体下颌骨左右两侧各拔除牙弓中段牙2颗,形成约20 mm无牙区.8周后在无牙区形成箱状缺损,同期取出支架即刻移植入一侧自体下颌骨缺损区,对侧骨缺损区直接移植入未经体内构建的磷酸钙陶瓷作为对照.结果与结论:经肌肉内构建的体内组织工程骨移植物的力学性能较单纯磷酸钙陶瓷有明显提高.颌骨缺损区的核吸收强度明显强于对照区,其移植物内长入的骨组织较多,两者的成骨面积差异有非常显著性意义(P < 0.01).说明在修复颌骨大范围缺损中,体内组织工程骨移植物较单纯骨磷酸钙陶瓷替代材料表现出明显的力学和生物学优势,修复效果显著,有良好的应用前景.     

纳米羟基磷灰石/月交原/聚乳酸复合物与骨髓间充质干细胞修复兔下颌骨缺损

背景:为颌骨缺损患者选择适宜的骨移植材料替代自体骨是当前研究的热点.目的:观察纳米羟基磷灰石/胶原/聚乳酸与兔骨髓间充质干细胞复合物用于修复兔下颌骨缺损的能力,比较其与自体骨修复及单纯纳米羟基磷灰石/胶原/聚乳酸修复的差异.设计、时间及地点:随机对照动物实验,于2007-03/10在锦州市中心医院动物实验室完成.材料:40只新西兰兔随机分成纳米羟基磷灰石/胶原/聚乳酸复合骨髓基质干细胞填充组(简称复合组)、自体骨填充组、单纯支架材料填充组及空白对照组,每组10只.方法:在兔下颌骨体部制造大小为15 mm×15 mm的全厚骨缺损模型.复合组于缺损处植入骨髓基质十细胞与纳米羟基磷灰石/胶原/聚乳酸体外联合培养14 d的复合物:自体骨填充组于缺损处植入自体髂骨;单纯支架材料充填组于缺损处植入纳米羟基磷灰石/胶原/聚乳酸:空白对照组不作任何植入.主要观察指标:分别于植入后1,3,6个月进行骨密度检测及组织学染色观察,根据检测结果评价骨修复效果.结果:复合组与自体骨填充组骨密度比较,差异无显著性(P＞0.05),且均高于单纯支架材料充填组及空白对照组(p＜0.01).复合组和自体骨填充组材料植入后6个月时见,新生骨组织渐成熟.呈大块状,桥接缺损断端,支架材料已所剩无几.单纯支架材料充填组植入后6个月时见,植入区骨小梁增多,但仍见较多纤维组织嵌于其中,易见未降解完全的支架材料.结论:纳米羟基磷灰石/胶原/聚乳酸与骨髓间充质干细胞复合物修复下颌骨缺损效果与自体骨修复相似,均优于单纯支架材料修复.     

Rat bone marrow stromal cells‐seeded porous gelatin/tricalcium phosphate/oligomeric proanthocyanidins composite scaffold for bone repair

Repair of bone defects remains a major challenge in orthopaedic surgery. Bone tissue engineering is an attractive approach for treating bone loss in various shapes and amounts. The aim of this study was to prepare and evaluate the feasibility of a porous scaffold, which was composed of oligomeric proanthocyanidin crosslinked gelatin mixed with β‐tricalcium phosphate (GTP) and was seeded with bone marrow stromal cells (BMSCs) as a bone substitute. GTP scaffolds were made porous using a salt‐leaching method. The physicochemical properties of the scaffold were evaluated to determine the optimal salt:composite weight ratio. The results indicated that the GTP scaffold had a favourable macroporous structure and higher porosity when the salt:composite weight ratio was 4:1. Cytotoxic tests demonstrated that extracts from the GTP scaffolds promoted the proliferation of BMSCs. Rat BMSCs were seeded on a GTP scaffold and cultured in a spinner flask. After 2 weeks of culture, scanning electron microscopy observation showed that the cells adhered well to the surfaces of the pores in the scaffold. Moreover, this study explored the biological response of rat calvarial bone to the scaffold to evaluate its potential in bone tissue engineering. Bone defects were filled with BMSC‐seeded GTP scaffold and acellular GTP scaffold. After 8 weeks, the scaffold induced new bone formation at a bone defect, as was confirmed by X‐ray microradiography and histology. The BMSC‐seeded scaffold induced more new bone formation than did an acellular scaffold. These observations suggest that the BMSCs‐seeded GTP scaffold can promote the regeneration of defective bone tissue. Copyright © 2012 John Wiley & Sons, Ltd.     

Bone marrow stromal cells enhance the osteogenic properties of hydroxyapatite scaffolds by modulating the foreign body reaction

We aimed to investigate the osteogenic properties of bone marrow stromal cell (BMSC)‐loaded biomimetic constructs composed of hydroxyapatite (HA), with or without in vitro cell‐derived extracellular matrix (HA‐ECM), and to assess the cellular components of the elicited foreign body reaction. HA‐ECM constructs were produced by adult rat dermal fibroblasts cultured on top of synthetic HA microparticles. Rat calvarial critical‐sized defects (8 mm) were created and treated with the generated HA‐ECM constructs or HA microparticles, alone or combined with green fluorescent protein (GFP)‐expressing BMSCs. The new bone formation and the local cellular inflammatory response (macrophages, neutrophils, lymphocytes, eosinophils and PCNA‐index) were assessed by histomorphometry and immunohistochemistry at 2 and 12 weeks postoperatively. In addition, the BMSCs' survival and engraftment were checked. The largest volume of the newly formed bone was found in defects treated with HA‐ECM constructs combined with BMSCs (p < 0.05). Moreover, the implanted BMSCs modulated the local inflammatory response, demonstrated by either a significant increase (HA vs HA + BMSCs) or decrease (HA‐ECM vs HA‐ECM + BMSCs) of the inflammatory cell number. No donor BMSCs were detected at the site of implantation or in the host bone marrow at 2 or 12 weeks postoperatively. In conclusion, the treatment of critical‐sized calvarial defects with the BMSC‐loaded biomimetic constructs has significantly enhanced bone repair by modulating the foreign body reaction. Our findings highlight the implications of BMSCs in the regulation of the foreign body reaction triggered by tissue‐engineered constructs, proving a higher efficiency for the BMSC combination therapy. Copyright © 2012 John Wiley & Sons, Ltd.     

An in vivo study on the effect of scaffold geometry and growth factor release on the healing of bone defects

The hypothesis of this study was that the extent of bone regeneration could be enhanced by using scaffolds with appropriate geometry, and that such an effect could be further increased by mimicking the natural timing of appearance of bone morphogenetic proteins BMP‐2 and BMP‐7 after fracture. Bioplotted poly(ε‐caprolactone) (PCL) disks with four different fibre organizations were used to study the effect of 3D scaffold architecture on the healing of bone defects in a rat pelvis model. Moreover, one PCL construct was further modified by introducing a nanoparticulate sequential BMP‐2/BMP‐7 delivery system into this scaffold. Scaffolds and functionalized construct along with free nanocapsules were implanted using a rat iliac crest defect model. Six weeks post‐implantation, the defects were evaluated by CT scan and histology. Analysis revealed that the basic architecture, having the highest pore volume for tissue ingrowth, presented the highest bone formation as determined by the bone mineral density (BMD) within the defect (144.2 ± 7.1); about four‐fold higher than that of the empty defect (34.9 ± 10.7). It also showed the highest histological analysis scores with a high amount of bone formation within the defect, within the scaffold pores and along the outer surfaces of the scaffold. The basic scaffold carrying the BMP‐2/BMP‐7 delivery system showed significantly higher bone formation than the growth factor‐free basic scaffold at 6 weeks (BMD 206.8 ± 15.7). Histological analysis also revealed new bone formation in close to or in direct contact with the construct interface. This study indicates the importance of open and interconnecting pore geometry on the better healing of bone defects, and that this effect could be further increased by supplying growth factors, as is the case in nature. Copyright © 2012 John Wiley & Sons, Ltd.     

Comparison of three different types of scaffolds preseeded with human bone marrow mononuclear cells on the bone healing in a femoral critical size defect model of the athymic rat

Large bone defects often pose major difficulties in orthopaedic surgery. The application of long‐term cultured stem cells combined with a scaffold lead to a significant improvement of bone healing in recent experiments but is strongly restricted by European Union law. Bone marrow mononuclear cells (BMC), however, can be isolated and transplanted within a few hours and have been proven effective in experimental models of bone healing. The effectivity of the BMC‐supported therapy might be influenced by the type of scaffold. Hence, we compared three different scaffolds serving as a carrier for BMC in a rat femoral critical size defect with regard to the osteogenic activity in the defect zone. Human demineralized bone matrix (DBM), bovine cancellous bone hydroxyapatite ceramic (BS), or β‐tricalcium phosphate (β‐TCP) were seeded with human BMC and hereafter implanted into critically sized bone defects of male athymic nude rats. Autologous bone served as a control. Gene activity was measured after 1 week, and bone formation was analysed histologically and radiologically after 8 weeks. Generally, regenerative gene expression (BMP2, RUNX2, VEGF, SDF‐1, and RANKL) as well as bony bridging and callus formation was observed to be most pronounced in defects filled with autologous bone, followed in descending order by DBM, β‐TCP, and BS. Although DBM was superior in most aspects of bone regeneration analysed in comparison to β‐TCP and BS, the level of autologous bone could not be attained.     

A novel oxysterol promotes bone regeneration in rabbit cranial bone defects

Bone morphogenetic proteins (BMPs) have played a central role in the development of regenerative therapies for bone reconstruction. However, the high cost and side‐effect profile of BMPs limits their broad application. Oxysterols, naturally occurring products of cholesterol oxidation, are promising osteogenic agents alternative to BMPs. The osteogenic capacity of these non‐toxic and relatively inexpensive molecules has been documented in rodent models. We studied the impact of Oxy49, a novel oxysterol analogue, on the osteogenic differentiation of rabbit bone marrow stromal cells (BMSCs). Moreover, we evaluated the capacity for in vivo bone regeneration with Oxy49 in rabbit cranial bone defects. We found that rabbit BMSCs treated with Oxy49 demonstrated differentiation along osteogenic pathways, and that complete bone regeneration occurred when cranial defects were treated with Oxy49. Collectively, these results demonstrate that Oxy49 has the ability to induce osteogenic differentiation in rabbit BMSCs with an efficacy comparable to that of BMP‐2 and to promote significant bone regeneration in cranial defects. Oxysterols may be a viable novel agent in bone tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd.