A biomimetic multi-layered collagen-based scaffold for osteochondral repair

Cartilage and osteochondral defects pose a significant challenge in orthopedics. Tissue engineering has shown promise as a potential method for the treatment of such defects; however, a long-lasting repair strategy has yet to be realized. This study focuses on the development of a layered construct for osteochondral repair, fabricated through a novel “iterative layering” freeze-drying technique. The process involved repeated steps of layer addition followed by freeze-drying, enabling control over material composition, pore size and substrate stiffness in each region of the construct, while also achieving a seamlessly integrated layer structure. The novel construct developed mimics the inherent gradient structure of healthy osteochondral tissue: a bone layer composed of type I collagen and hydroxyapatite (HA), an intermediate layer composed of type I collagen, type II collagen and HA and a cartilaginous region composed of type I collagen, type II collagen and hyaluronic acid. The material properties were designed to provide the biological cues required to encourage infiltration of host cells from the bone marrow while the biomechanical properties were designed to provide an environment optimized to promote differentiation of these cells towards the required lineage in each region. This novel osteochondral graft was shown to have a seamlessly integrated layer structure, high levels of porosity (>97%), a homogeneous pore structure and a high degree of pore interconnectivity. Moreover, homogeneous cellular distribution throughout the entire construct was evident following in vitro culture, demonstrating the potential of this multi-layered scaffold as an advanced strategy for osteochondral defect repair.     

Radially oriented collagen scaffold with SDF-1 promotes osteochondral repair by facilitating cell homing

The migration of cells from the side and the bottom of the defect is important in osteochondral defect healing. Here, we designed a novel collagen scaffold that possessed channels in both the horizontal and the vertical directions, along with stromal cell-derived factor-1 (SDF-1) to enhance osteochondral regeneration by facilitating cell homing. Firstly we fabricated the radially oriented and random collagen scaffolds, then tested their properties. The radially oriented collagen scaffold had better mechanical properties than the random scaffold, but both supported cell proliferation well. Then we measured the migration of BMSCs in the scaffolds in vitro. The radially oriented collagen scaffold effectively promoted their migration, and this effect was further facilitated by addition of SDF-1. Moreover, we created osteochondral defects in rabbits, and implanted them with random or oriented collagen scaffolds with or without SDF-1, and evaluated cartilage and subchondral bone regeneration at 6 and 12 weeks after surgery. Cartilage regeneration with both the radially oriented scaffold and SDF-1 effectively promoted repair of the cartilage defect. Our results confirmed that the implantation of the radially oriented channel collagen scaffold with SDF-1 could be a promising strategy for osteochondral repair.     

Bi-layer collagen/microporous electrospun nanofiber scaffold improves the osteochondral regeneration

An optimal scaffold is crucial for osteochondral regeneration. Collagen and electrospun nanofibers have been demonstrated to facilitate cartilage and bone regeneration, respectively. However, the effect of combining collagen and electrospun nanofibers on osteochondral regeneration has yet to be evaluated. Here, we report that the combination of collagen and electrospun poly-l-lactic acid nanofibers synergistically promotes osteochondral regeneration. We first fabricated bi-layer microporous scaffold with collagen and electrospun poly-l-lactic acid nanofibers (COL-nanofiber). Mesenchymal stem cells were cultured on the bi-layer scaffold and their adhesion, proliferation and differentiation were examined. Moreover, osteochondral defects were created in rabbits and implanted with COL-nanofiber scaffold. Cartilage and subchondral bone regeneration were evaluated at 6 and 12 weeks after surgery. Compared with COL scaffold, cells on COL-nanofiber scaffold exhibited more robust osteogenic differentiation, indicated by higher expression levels of OCN and runx2 genes as well as the accumulation of calcium nodules. Furthermore, implantation of COL-nanofiber scaffold seeded with cells induced more rapid subchondral bone emergence, and better cartilage formation, which led to better functional repair of osteochondral defects as manifested by histological staining, biomechanical test and micro-computed tomography data. Our study underscores the potential of using the bi-layer microporous COL-nanofiber scaffold for the treatment of deep osteochondral defects.     

羟基丁酸-羟基辛酸共聚体/胶原骨软骨一体化支架修复膝关节软骨损伤

BACKGROUND: Due to the complex physiological characteristics of the osteochondral tissue, the clinical repair of knee cartilage injury often has dissatisfied outcomes. Tissue engineering methods and tools provide a new idea for osteochondral repair. OBJECTIVE: To observe the effect of poly(hydroxybutyrate-co-hydroxyoctanoate/collagen) osteochondral tissue-engineered scaffold on the repair of articular cartilage injury in a rabbit. METHODS: The poly(hydroxybutyrate-co-hydroxyoctanoate/collagen) osteochondral tissue-engineered scaffold was prepared by solvent casting/particle leaching method. Then, seed cells were isolated and cultured on the scaffold. Twenty-four healthy New Zealand white rabbits, 4 weeks of age, were used for the study. Under balanced anesthesia, an articular cartilage defect (4.5 mm in diameter, 5 mm in depth) was created on the rabbit’s femoral condyle using a bone drill. After modeling, rabbits were randomized into three groups and given direct suture in blank group, pure scaffold implantation in control group and implantation of the scaffold-cell complex in experimental group. Femoral condyle of each rabbit was taken out for gross and histological observations at 8, 20 weeks after surgery. RESULTS AND CONCLUSION: At 8 weeks after surgery, transparent film-covered defects and small/irregular cells were found in the experimental group; the defects were filled with fibrous tissues in the control group; while there was no repair in the blank group. Until the 20th week, the defects were covered with hyaline cartilage-like tissues, accompanied by regular cell arrangement in the experimental group; in the control group, the defects were covered with white membranous tissues, and many chondrocytes were found at the basement and edge; in the blank group, some newborn tissues were visible at the defect region. These findings suggest that the poly (hydroxybutyrate-co- hydroxyoctanoate/collagen) osteochondral tissue-engineered scaffold carrying seed cells contributes to articular cartilage repair.     

Evaluation of a hybrid scaffold/cell construct in repair of high-load-bearing osteochondral defects in rabbits

The objective of this study was to evaluate the feasibility and potential of a hybrid scaffold system in large- and high-load-bearing osteochondral defects repair. The implants were made of medical-grade PCL (mPCL) for the bone compartment whereas fibrin glue was used for the cartilage part. Both matrices were seeded with allogenic bone marrow-derived mesenchymal cells (BMSC) and implanted in the defect (4 mm diameter x 5 mm depth) on medial femoral condyle of adult New Zealand White rabbits. Empty scaffolds were used at the control side. Cell survival was tracked via fluorescent labeling. The regeneration process was evaluated by several techniques at 3 and 6 months post-implantation. Mature trabecular bone regularly formed in the mPCL scaffold at both 3 and 6 months post-operation. Micro-Computed Tomography showed progression of mineralization from the host-tissue interface towards the inner region of the grafts. At 3 months time point, the specimens showed good cartilage repair. In contrast, the majority of 6 months specimens revealed poor remodeling and fissured integration with host cartilage while other samples could maintain good cartilage appearance. In vivo viability of the transplanted cells was demonstrated for the duration of 5 weeks. The results demonstrated that mPCL scaffold is a potential matrix for osteochondral bone regeneration and that fibrin glue does not inherit the physical properties to allow for cartilage regeneration in a large and high-load-bearing defect site.     

Autologous chondrocyte implantation with collagen bioscaffold for the treatment of osteochondral defects in rabbits

Osteochondral injury is therapeutically irreversible within current treatment parameters. Autologous chondrocyte implantation (ACI) promises to regenerate hyaline articular cartilage, but conventional ACI is plagued by complications determined by periosteal grafting. Here we propose the utilization of collagen membrane in ACI as an effective bioscaffold for the regeneration of osteochondral lesions. Using a rabbit model of osteochondral injury, we have inoculated autologous chondrocytes onto a type I/III collagen scaffold [so-called matrix-induced ACI (MACI)] and implanted into 3-mm osteochondral knee defects. All untreated defect histology showed inferior fibrocartilage and/or fibrous tissue repair. In our time-course study, ACI with type I/III collagen membrane regenerated cartilage with healthy osteochondral architecture in osteochondral defects at 6 weeks. At 12 weeks, articular cartilage regeneration was maintained, with reduced thickness and proteoglycan compared with the adjacent cartilage. Both 6-week (p < 0.01) and 12-week (p < 0.05) ACI with collagen membrane showed significant improvement as compared with untreated controls. To further examine the efficacy of cartilage regeneration by ACI, we conducted a dose-response study, using chondrocytes at various cell densities between 10(4) and 10(6) cells/cm(2). The results showed that cell density had no effect on outcome histology, but all cell densities were significantly better than untreated controls (p < 0.01) and cell-free collagen membrane treatment (p < 0.05). In short, our data suggest that autologous chondrocyte-seeded type I/III collagen membrane is an effective method for the treatment of focal osteochondral knee injury in rabbits.     

Effect of the size and location of osteochondral defects in degenerative arthritis. A finite element simulation

Physiological studies have shown that focal articular surface defects in the human knee may progress to degenerative arthritis. Although the risk of this evolutive process is multifactorial, defect size is one of the most important factors. In order to determine the influence of osteochondral defect size and location on the stress and strain concentrations around the defect rim, a finite element model of the human knee was developed. From our results, it became clear that the size and location of cartilage defects drastically affect to those variables. No stress concentration appeared around the rim of small defects, being the stress distribution mainly controlled by the meniscus contact. On the contrary, important rim stress concentration was found for large osteochondral defects. This alteration of the stress distribution has important clinical implications regarding the long-term integrity of the cartilage adjacent to osteochondral defects.     

旋转反应器胶原支架的制备及复合软骨细胞修复骨软骨损伤的初步研究

目的以胶原为原料开发一种小型胶原支架材料,尝试是否适合旋转反应器来复合软骨细胞,并探讨复合细胞后修复软骨损伤的效果。方法成年猪跟腱中提取胶原,制备胶原支架,进行细胞毒性检测和生物相容性分析。将其切成1 mm~3小块,置于旋转培养器中与软骨细胞共培养,倒置相差显微镜观察细胞贴附效果。建立兔关节软骨缺损模型,编号后,将14只新西兰大白兔随机分为2组:支架材料组(n=8),兔膝关节软骨缺损区植入胶原支架材料和软骨细胞;空白对照组(n=6),不进行任何植入处理。进行HE染色后观察。结果胶原支架呈瓷白色,表面空隙均匀,无细胞毒性,生物相容性良好,但在体内降解较快。在旋转反应器中,支架可以与软骨细胞良好结合。胶原支架植入动物体内12周,虽未完全修复缺损,但已有少量软骨细胞在缺损处出现,修复效果优于对照组。结论制备的胶原支架复合软骨细胞短期内有一定的修复软骨缺损的能力,长期效果欠佳,可能与胶原支架在体内过快降解有关,尚需对制备方法进行改进。     

Evaluation of multiphase implants for repair of focal osteochondral defects in goats

The use of biodegradable scaffolds for articular cartilage repair has been investigated by numerous researchers. The objective of this screening study was to examine how the mechanical and physical properties of four multiphase implants can affect the cartilage healing response. Multiphase implant prototypes were prepared using poly(D,L)lactide-co-glycolide as the base material. PGA fibers (FR), 45S5 Bioglass (BG) and medical grade calcium sulfate (MGCS) were used as additives to vary stiffness and chemical properties. Osteochondral defects (3 mm dia. and 4 mm in depth) were created bilaterally in the medial femoral condyle (high-weight bearing) and the distal medial portion of the patellar groove (low-weight bearing) of 16 Spanish goats. Half of the implants were loaded with autologous costochondral chondrocytes. Defect sites (total n = 64, 4 sites/treatment) were randomly treated and allowed to heal for 16 weeks, fully weight bearing. At euthanasia, gross evaluations and biomechanical testing were conducted. Histological sections of the defect sites were stained with H and E, Safranin O/Fast Green or processed to analyze collagen architecture. Sections were semi-quantitatively scored for repair tissue structure. Qualitative evaluations showed that all groups had a high percentage of hyaline cartilage and good bony restoration, with new tissue integrating well with the native cartilage. Gross and histology scoring indicated a significantly higher score for defect healing in the condyle than in the patellar groove, but no difference in healing for implant types or addition/omission of cells was found. This investigation demonstrates that focal, osteochondral defects in caprine distal femurs treated with various implant constructs were repaired with hyaline-like cartilage and good underlying bone. The multiphase implants show potential for treatment of osteochondral defects and long-term studies need to be undertaken to confirm the longevity of the regenerated tissue.     

Articular chondroprogenitors in platelet rich plasma for treatment of osteoarthritis and osteochondral defects in a rabbit knee model

BackgroundArticular chondroprogenitors are a promising contender for cartilage repair due to their inherent nature which stands primed for chondrogenesis and minimal hypertrophic preponderance. Platelet rich plasma (PRP) has been extensively used for treating cartilage defects and osteoarthritis (OA), due to its chondro-inductive properties and abundant pool of growth factors. The aim of this study was to assess the efficacy of chondroprogenitors injected with PRP versus PRP alone in the healing of experimentally created early OA and osteochondral defects (OCD) in a rabbit model.MethodsAdult New Zealand White male rabbits were used for cell and PRP isolation. Chondroprogenitors were isolated by fibronectin adhesion assay, labelled with iron oxide, characterized for surface markers, differential potential and expanded. PRP was isolated by double spin centrifugation using a TriCell kit. Study groups included (a) Monosodium iodoacetate induced early OA and (b) critical OCD. Following intervention (test arm: PRP+ chondroprogenitors and control arm: PRP), assessment was performed at 6- and 12-weeks which included histopathological examination and scoring (OARSI and Modified Wakitani score), immunohistochemistry analysis (Collagen type II and X) and synovial fluid S100A12 levels.Results and conclusionComparable, evident healing was noticed in both test and control arms when the OA group samples were assessed at both time points. In the OCD group, PRP alone exhibited significantly better results than the test arm, although repair was notable in both interventions. Further evaluation of chondroprogenitors is required to assess their role as a standalone therapy and in combination with PRP to further cartilage regeneration.     

Novel hydroxyapatite/chitosan bilayered scaffold for osteochondral tissue-engineering applications: Scaffold design and its performance when seeded with goat bone marrow stromal cells

Recent studies suggest that bone marrow stromal cells are a potential source of osteoblasts and chondrocytes and can be used to regenerate damaged tissues using a tissue-engineering (TE) approach. However, these strategies require the use of an appropriate scaffold architecture that can support the formation de novo of either bone and cartilage tissue, or both, as in the case of osteochondral defects. The later has been attracting a great deal of attention since it is considered a difficult goal to achieve. This work consisted on developing novel hydroxyapatite/chitosan (HA/CS) bilayered scaffold by combining a sintering and a freeze-drying technique, and aims to show the potential of such type of scaffolds for being used in TE of osteochondral defects. The developed HA/CS bilayered scaffolds were characterized by Fourier transform infra-red spectroscopy, X-ray diffraction analysis, micro-computed tomography, and scanning electron microscopy (SEM). Additionally, the mechanical properties of HA/CS bilayered scaffolds were assessed under compression. In vitro tests were also carried out, in order to study the water-uptake and weight loss profile of the HA/CS bilayered scaffolds. This was done by means of soaking the scaffolds into a phosphate buffered saline for 1 up to 30 days. The intrinsic cytotoxicity of the HA scaffolds and HA/CS bilayered scaffolds extract fluids was investigated by carrying out a cellular viability assay (MTS test) using Mouse fibroblastic-like cells. Results have shown that materials do not exert any cytotoxic effect. Complementarily, in vitro (phase I) cell culture studies were carried out to evaluate the capacity of HA and CS layers to separately, support the growth and differentiation of goat marrow stromal cells (GBMCs) into osteoblasts and chondrocytes, respectively. Cell adhesion and morphology were analysed by SEM while the cell viability and proliferation were assessed by MTS test and DNA quantification. The chondrogenic differentiation of GBMCs was evaluated measuring the glucosaminoglycans synthesis. Data showed that GBMCs were able to adhere, proliferate and osteogenic differentiation was evaluated by alkaline phosphatase activity and immunocytochemistry assays after 14 days in osteogenic medium and into chondrocytes after 21 days in culture with chondrogenic medium. The obtained results concerning the physicochemical and biological properties of the developed HA/CS bilayered scaffolds, show that these constructs exhibit great potential for their use in TE strategies leading to the formation of adequate tissue substitutes for the regeneration of osteochondral defects.     

用组织工程学方法探讨兔佐剂性关节炎关节软骨修复的实验研究

目的探讨海藻酸盐支架超微结构及软骨形态变化与组织工程修复佐剂性关节炎软骨缺损的关系,为临床应用组织工程方法治疗类风湿性关节炎(rheumatoid arthritis,RA)提供一定的实验依据。方法将24只新西兰兔随机均分为假手术对照组,关节炎模型组和软骨细胞-海藻酸钙支架复合物治疗组。对模型组和治疗组膝关节处注射0.5 m L完全弗氏佐剂诱导关节炎,假手术组注射等量生理盐水。抽取治疗组骨髓5 m L,Percoll密度梯度分离出自体骨髓间充质干细胞,体外培养纯化,并诱导分化成软骨细胞。与海藻酸钙支架混合培养,对支架进行扫描电镜观察,并将混合物回注相应关节腔内治疗1个月。对各组兔膝关节进行组织学评分检测软骨缺损修复结果。结果海藻酸盐支架电镜扫描显示支架具有一定的孔隙,有利于营养物质的进入,便于细胞的增殖分化。软骨组织评分结果显示软骨纤维化减轻,关节腔内积液消失,软骨缺损得到一定修复。结论软骨组织评分显示海藻酸钙复合工程化软骨细胞对兔佐剂性关节炎软骨缺损有一定的修复作用,其机制可能与支架有利于软骨细胞生长发育有关。     

多孔丝素蛋白支架修复兔下颌骨临界性骨缺损

背景：丝素蛋白具有良好的生物相容性和可降解性。 目的：观察多孔丝素蛋白支架原位修复兔下颌骨临界性骨缺损效果。 方法：建立兔双侧下颌骨临界性骨缺损模型,随机选取一侧缺损植入多孔丝素蛋白支架作为实验组,另一侧缺损不作处理作为对照组。 结果与结论：①大体标本：术后12周,实验组骨缺损腔表面完全被新生骨覆盖,材料无脱出;对照组骨缺损腔内充满肉芽组织,骨不连。②X射线骨密度测定：术后2,6,12周,两组骨密度均随着时间延长逐渐增高,组内不同时间点间差异有显著性意义(P < 0.05),且同期实验组高于对照组(P < 0.05)。③组织病理切片苏木精-伊红染色：术后12周,实验组岛状新生骨及骨小梁明显增多,而且粗大而致密,材料内部明显疏松,部分区域塌陷;对照组宿主骨边缘可见散在分布的新生骨组织,但并无粗大骨小梁形成。④骨形态发生蛋白2免疫组织化学染色：术后2,6,12周,两组骨形态发生蛋白2阳性细胞数均随着时间延长逐渐增多,组内不同时间点间差异有显著性意义(P < 0.05),且同期实验组多于对照组 (P < 0.05)。表明多孔丝素蛋白支架用于原位组织工程修复骨缺损具有一定可行性。     

胶原/羟基磷灰石复合材料的制备及用于骨缺损修复的研究现状

通过模拟天然骨的结构,制备胶原/羟基磷灰石复合材料,与天然骨具有相似的组成、结构和性能,并具有良好的生物活性和生物降解性。本文就胶原/羟基磷灰石复合材料的制备方法、仿生形成机制、表征手段及骨缺损修复的应用等进行综述,并展望其未来发展方向。     

rhBMP-2和bFGF复合至壳聚糖-Ⅰ型胶原支架后在体外的降解和释放

目的： 探讨rhBMP-2和bFGF复合至壳聚糖-Ⅰ型胶原支架材料后在体外的释放规律。方法: 制备壳聚糖-Ⅰ型胶原支架及含rhBMP-2和bFGF的复合膜。扫描电镜观察测量支架孔径；体外观察降解情况,在不同时点收集浸出液，ELISA检测因子的释放浓度；观察浸出液对牙周膜细胞的影响。结果： 复合膜呈疏松多孔海绵状，高、中、低3种壳聚糖-Ⅰ型胶原支架平均孔径分别为（106±17）μm、（141±13）μm和（173±11）μm ；复合膜在含溶菌酶的PBS中可以降解，壳聚糖浓度越高支架降解越慢，rhBMP-2和bFGF的释放开始为“爆发性”，此后释放逐渐减慢，最后在低浓度可缓慢而持久地释放，壳聚糖浓度越高的复合支架，因子释放越慢越持久。与含溶菌酶的PBS间接接触的因子层随着其表面支架的降解而逐渐释放因子，释放延迟时间和表面支架的降解速度有关。复合bFGF因子支架的浸出液作用于HPDLCs，可以明显促进细胞的增殖。结论： 壳聚糖-Ⅰ型胶原复合因子支架体外可以降解并释放因子，降解和因子释放速度与壳聚糖的浓度密切相关；可以通过分层制作复合因子支架来控制因子有序释放，所释放的因子具有正常生物学功能。     

硼酸盐生物玻璃和自体髂骨移植对新西兰兔桡骨大段骨缺损修复的对比研究

目的比较硼酸盐生物玻璃和自体髂骨移植对新西兰兔桡骨大段骨缺损的修复效果。方法取38只新西兰兔,制作桡骨干15 mm骨缺损动物模型,并将其随机分为空白组(8只)、对照组(15只)和实验组(15只),对照组和实验组分别植入自体髂骨和硼酸盐生物玻璃(borate glass, BG)。术后4、8和12周行X线检查,观察材料的降解和新生骨生成情况。术后6周和9周分别腹腔注射茜素红和钙黄绿素。术后12周取材行组织学和Micro-CT检查。结果影像学和组织学结果显示对照组和实验组新骨生成明显优于空白组,12周后对照组和实验组新骨完全修复缺损;实验组材料降解与新骨生成协调进行;术后12周缺损处组织学切片显示,对照组和实验组缺损处有大量的新生骨组织。结论硼酸盐生物玻璃可完全修复兔桡骨干大段骨缺损,其修复效果与自体髂骨移植接近,在骨组织工程领域有广阔的应用前景。     

A prospective, randomised study comparing two techniques of autologous chondrocyte implantation for osteochondral defects in the knee: Periosteum covered versus type I/III collagen covered

INTRODUCTION: The results for autologous chondrocyte implantation (ACI) in the treatment of full thickness chondral defects in the knee are encouraging. At present two techniques have been described to retain the chondrocyte suspension within the defect. The first involves using a periosteal cover (ACI-P) and the second involves using a type I/III collagen membrane (ACI-C). To the authors knowledge there are no comparative studies of these two techniques in the current literature. We have therefore undertaken such a study to establish if there is a difference between the 2 techniques based on a clinical and arthroscopic assessment. METHODS: A total of 68 patients with a mean age of 30.52 years with symptomatic articular cartilage defects were randomised to have either ACI-P (33 patients) or ACI-C (35 patients). The mean defect size was 4.54 cm2. All patients were followed up at 24 months. RESULTS: A clinical and functional assessment showed that 74% of patients had a good or excellent result following the ACI-C compared with 67% after the ACI-P at 2 years. Arthroscopy at 1 year also demonstrated similar results for both techniques. However, 36.4% of the ACI-P grafts required shaving for hypertrophy compared with none for the ACI-C grafts at 1 year. DISCUSSION: This study has shown no statistical difference between the clinical outcome of ACI-C versus ACI-P at 2 years. A significant number of patients who had the ACI-P required shaving of a hypertrophied graft. We conclude that there is no advantage in using periosteum as a cover for retaining chondrocytes within an osteochondral defect; as a result we advocate the use of an alternative cover such as a manufactured type I/III collagen membrane.     

Phytomolecule icaritin incorporated PLGA/TCP scaffold for steroid-associated osteonecrosis: Proof-of-concept for prevention of hip joint collapse in bipedal emus and mechanistic study in quadrupedal rabbits

Steroid-associated osteonecrosis (SAON) may lead to joint collapse and subsequent joint replacement. Poly lactic-co-glycolic acid/tricalcium phosphate (P/T) scaffold providing sustained release of icaritin (a metabolite of Epimedium-derived flavonoids) was investigated as a bone defect filler after surgical core-decompression (CD) to prevent femoral head collapse in a bipedal SAON animal model using emu (a large flightless bird). The underlying mechanism on SAON was evaluated using a well-established quadrupedal rabbit model. Fifteen emus were established with SAON, and CD was performed along the femoral neck for the efficacy study. In this CD bone defect, a P/T scaffold with icaritin (P/T/I group) or without icaritin (P/T group) was implanted while no scaffold implantation was used as a control. For the mechanistic study in rabbits, the effects of icaritin and composite scaffolds on bone mesenchymal stem cells (BMSCs) recruitment, osteogenesis, and anti-adipogenesis were evaluated. Our efficacy study showed that P/T/I group had the significantly lowest incidence of femoral head collapse, better preserved cartilage and mechanical properties supported by more new bone formation within the bone tunnel. For the mechanistic study, our in vitro tests suggested that icaritin enhanced the expression of osteogenesis related genes COL1α, osteocalcin, RUNX2, and BMP-2 while inhibited adipogenesis related genes C/EBP-ß, PPAR-γ, and aP2 of rabbit BMSCs. Both P/T and P/T/I scaffolds were demonstrated to recruit BMSCs both in vitro and in vivo but a higher expression of migration related gene VCAM1 was only found in P/T/I group in vitro. In conclusion, both efficacy and mechanistic studies show the potential of a bioactive composite porous P/T scaffold incorporating icaritin to enhance bone defect repair after surgical CD and prevent femoral head collapse in a bipedal SAON emu model.     

透钙磷石骨水泥复合明胶及重组人骨形态发生蛋白2/7修复骨缺损

文题释义：明胶：是胶原蛋白的水解产物,具有优异的生物降解性、细胞相容性和无免疫原性。在30-40 ℃时,明胶由固态转化为溶液,明胶溶液与戊二醛共价交联后形成水凝胶中的水可作为致孔剂,增加支架材料的孔隙率,改变支架材料中孔结构的大小。骨形态发生蛋白：是一组能够诱导和促进骨形成的细胞因子,属于转化生长因子超家族成员,是骨组织工程中最重要的骨诱导生长因子,分为同源二聚体和异源二聚体,其中骨形态发生蛋白2、骨形态发生蛋白7、骨形态发生蛋白2/7的研究最为广泛,骨形态发生蛋白2/7的成骨效果优于骨形态发生蛋白2和骨形态发生蛋白7。背景：课题组前期研究发现10%锶-透钙磷石的成骨能力高于透钙磷石和5%锶-透钙磷石,但也发现掺锶透钙磷石的孔结构不够理想,前期成骨效果不佳。 目的：在10%锶-透钙磷石中加入明胶和重组人骨形态发生蛋白2/7(recombinant Human bone morphogenetic proteins 2/7,rhBMP2/7),观察其修复家兔下颌骨缺损的成骨效果。方法：分别制备明胶-10%锶-透钙磷石与含0.04,1 g/L rhBMP2/7的明胶-10%锶-透钙磷石材料。在45只家兔双侧下颌骨制作骨缺损模型,分5组干预：空白对照组不植入任何材料,其余4组分别植入10%锶-透钙磷石(对照组)、明胶-10%锶-透钙磷石(明胶组)、0.04 g/L rhBMP2/7-明胶-10%锶-透钙磷石(0.04 g/L rhBMP2/7组)、1 g/L rhBMP2/7-明胶-10%锶-透钙磷石(1 g/L rhBMP2/7组)。术后4,8,12周取骨缺损标本,分别进行锥形束CT与免疫组化观察。实验经华北理工大学实验动物伦理委员会审议批准。结果与结论：①锥形束CT：术后8周时,1 g/L rhBMP2/7组骨修复基本完成,新生骨组织与周围组织几乎融合;0.04 g/L rhBMP2/7组和胶原组缺损区大部分修复,新骨修复边缘不平整;对照组部分修复。术后12周时,明胶组、0.04,1 g/L rhBMP2/7组完成缺损区骨修复;②免疫组化观察：术后4,8周时,1 g/L rhBMP2/7组Ⅰ型胶原表达高于其他4组(P < 0.05),0.04 g/L rhBMP2/7组、胶原组高于对照组(P < 0.05);术后12周时,植入材料4组间Ⅰ型胶原表达比较差异无显著性意义(P > 0.05);③结果表明：在10%锶-透钙磷石中加入明胶和1 g/L的重组人骨形态发生蛋白2/7可促进骨缺损的修复。ORCID: 0000-0001-8461-8403(李雪微) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程