Real-time-guided bone regeneration around standardized critical size calvarial defects using bone marrow-derived mesenchymal stem cells and collagen membrane with and without using tricalcium phosphate: an in vivo microcomputed tomographic and histologic e

The aim of the present real time in vivo micro-computed tomography （pCT） and histologic experiment was to assess the efficacy of guided bone regeneration （GBR） around standardized calvarial critical size defects （CSD） using bone marrow-derived mesenchymal stem cells （BMSCs）, and collagen membrane （CM） with and without tricalcium phosphate （TCP） graft material. In the calvaria of nine female Sprague-Dawley rats, full-thickness CSD （diameter 4.6 mm） were created under general anesthesia. Treatment-wise, rats were divided into three groups. In group 1, CSD was covered with a resorbable CM; in group 2, BMSCs were filled in CSD and covered with CM; and in group 3, TCP soaked in BMSCs was placed in CSD and covered with CM. All defects were closed using resorbable sutures. Bone volume and bone mineral density of newly formed bone （NFB） and remaining TCP particles and rate of new bone formation was determined at baseline, 2, 4, 6, and 10 weeks using in vivo pCT. At the lOth week, the rats were killed and calvarial segments were assessed histologically. The results showed that the hardness of NFB was similar to that of the native bone in groups I and 2 as compared to the NFB in group 3. Likewise, values for the modulus of elasticity were also significantly higher in group 3 compared to groups 1 and 2. This suggests that TCP when used in combination with BMSCs and without CM was unable to form bone of significant strength that could possibly provide mechanical ＂lock＂ between the natural bone and NFB. The use of BMSCs as adjuncts to conventional GBR initiated new bone formation as early as 2 weeks of treatment compared to when GBR is attempted without adiunct BMSC therapy.

Porous titanium granules in critical size defects of rabbit tibia with or without membranes

Recently, porous titanium granules （PTGs） have been indicated for the preservation of the dimensions of post-extraction sockets, as a filler in sinus lift procedures and for the treatment of peri-implant and periodontal defects, based on the osteoconductivity and dimensional stability of the titanium granules. However, there is a lack of information regarding the use of this material in larger defects and in conjunction with membranes. The objective of this study is to test the behavior of PTGs used to fill critical size defects in rabbit tibiae, with and without membranes. Critical defects were created in both tibiae of rabbits, divided randomly into three groups： Group A （defect filled with PTG）, Group B （defect filled with PTG＋collagen membrane） and a control group （empty defect）. After six weeks, histomorphometric analysis was performed. The results showed more defect closures at the cortical area （87.37%±2.2%） and more bone formation at the marrow area （57.6%± 1.3%） in Group B, in comparison with the other groups （P〈0.05）; the use of membranes improved the material stability expressed as more percentages of the original material when membranes were used （P〈0.05）. Finally, inflammatory reactions were observed when the granules were not protected by membranes. In spite of the limitations of this animal study, it may be concluded that PTG particles are osteoconductive and allow bone growth. The PTG particles must be covered by a membrane, especially when grafting larger defects, in order to control particle migration, promote clot stabilization and separate the PTG graft from undesired soft tissue cells.

Early therapeutic effect of platelet-rich fibrin combined with allogeneic bone marrow-derived stem cells on rats’ critical-sized mandibular defects

BACKGROUND Critically sized bone defects represent a significant challenge to orthopaedic surgeons worldwide.These defects generally result from severe trauma or resection of a whole large tumour.Autologous bone grafts are the current gold standard for the reconstruction of such defects.However,due to increased patient morbidity and the need for a second operative site,other lines of treatment should be introduced.To find alternative unconventional therapies to manage such defects,bone tissue engineering using a combination of suitable bioactive factors,cells,and biocompatible scaffolds offers a promising new approach for bone regeneration.AIM To evaluate the healing capacity of platelet-rich fibrin(PRF)membranes seeded with allogeneic mesenchymal bone marrow-derived stem cells(BMSCs)on critically sized mandibular defects in a rat model.METHODS Sixty-three Sprague Dawley rats were subjected to bilateral bone defects of critical size in the mandibles created by a 5-mm diameter trephine bur.Rats were allocated to three equal groups of 21 rats each.Group I bone defects were irrigated with normal saline and designed as negative controls.Defects of group II were grafted with PRF membranes and served as positive controls,while defects of group III were grafted with PRF membranes seeded with allogeneic BMSCs.Seven rats from each group were killed at 1,2 and 4 wk.The mandibles were dissected and prepared for routine haematoxylin and eosin(HE)staining,Masson's trichrome staining and CD68 immunohistochemical staining.RESULTS Four weeks postoperatively,the percentage area of newly formed bone was significantly higher in group III(0.88±0.02)than in groups I(0.02±0.00)and II(0.60±0.02).The amount of granulation tissue formation was lower in group III(0.12±0.02)than in groups I(0.20±0.02)and II(0.40±0.02).The number of inflammatory cells was lower in group III(0.29±0.03)than in groups I(4.82±0.08)and II(3.09±0.07).CONCLUSION Bone regenerative quality of critically sized mandibular bone defects in rats was better promoted by PRF membranes seeded with BMSCs than with PRF membranes alone.

Healing Mechanism and Osteogenic Capacity of Bovine Bone Mineral—Human Amniotic Mesenchymal Stem Celland Autogenous Bone Graft in Critical Size Mandibular Defect

Experiments on maxillofacial bone tissue engineering showed the promising result;however, its healing mechanisms and effectiveness had not been fully understood. The aim of this study is to compare the bone healing mechanism and osteogenic capacity between bovine bone mineral loaded with hAMSC and autogenous bone graft in the reconstruction of critical size mandibular bone defect. Critical size defects were made at the mandible of 45 New Zealand white rabbits reconstructed with BBM-hAMSC, BBM alone, and ABG, respectively. At the end of first, second, and twelfth weeks, five rabbits from each experimental week were sacrificed for histology and immunohistochemistry staining. Expressions of vascular endothelial growth factor (VEGF), bone mor-phogenic proteins-2 (BMP2), Runx2 and the amount of angiogenesis were analyzed in the first and second week groups, while expressions of Runx2, osteocalcin, collagen type-I fibres, trabecular area and bone incorporation were analyzed in the twelfth week groups. The result showed that expressions of VEGF, BMP2 and Runx2 as well as the amount of angiogenesis were higher in ABG compared with BBM-hAMSC group in the first and second weeks of healing. The result of twelfth week of healing showed that expressions of Runx2 and osteocalcin as well as the thickness of collagen type-I fibres were significantly higher in BBM-hAMSC compared to ABG group, while there was no statistically difference in trabecular area and bone incorporation between BBM-hAMSC and ABG group. This study concluded that early healing activities were higher in auto-genous bone graft than in BBM-hAMSC, while osteogenic activities in the late stage of healing were higher in BBM-hAMSC compared to autogenous bone graft. It was also concluded that the osteo-genic capacity of BBM-hAMSC was comparable to autogenous bone graft in the reconstruction of critical size defect in the mandible.

Vascular restoration through local delivery of angiogenic factors stimulates bone regeneration in critical size defects

Critical size bone defects represent a significant challenge worldwide,often leading to persistent pain and physical disability that profoundly impact patients’quality of life and mental well-being.To address the intricate and complex repair processes involved in these defects,we performed single-cell RNA sequencing and revealed notable shifts in cellular populations within regenerative tissue.Specifically,we observed a decrease in progenitor lineage cells and endothelial cells,coupled with an increase in fibrotic lineage cells and pro-inflammatory cells within regenerative tissue.Furthermore,our analysis of differentially expressed genes and associated signaling pathway at the single-cell level highlighted impaired angiogenesis as a central pathway in critical size bone defects,notably influenced by reduction of Spp1 and Cxcl12 expression.This deficiency was particularly pronounced in progenitor lineage cells and myeloid lineage cells,underscoring its significance in the regeneration process.In response to these findings,we developed an innovative approach to enhance bone regeneration in critical size bone defects.Our fabrication process involves the integration of electrospun PCL fibers with electrosprayed PLGA microspheres carrying Spp1 and Cxcl12.This design allows for the gradual release of Spp1 and Cxcl12 in vitro and in vivo.To evaluate the efficacy of our approach,we locally applied PCL scaffolds loaded with Spp1 and Cxcl12 in a murine model of critical size bone defects.Our results demonstrated restored angiogenesis,accelerated bone regeneration,alleviated pain responses and improved mobility in treated mice.

股骨骨缺损动物模型制备现状及特点

背景:骨缺损的修复及后期临床转归仍是临床研究中的热点和难点,是困扰临床医师的常见问题。构建合适、可重复性及无限接近临床的动物实验模型及科学的评估对进一步的临床治疗相关疾病至关重要。目的:回顾性分析文献中股骨骨缺损常用实验动物模型制备方法及不同模型特点,评估优势与不足,为相关研究者选择合适的股骨骨缺损动物模型提供一定的参考。方法:检索PubMed、Web of Science、Medline数据库及CNKI数据库,设定英文检索词为:bone defect,bone,bones,defect,defects,defective,animal model,animal,model,laboratory,laboratory animal,animal laboratory;中文检索词为:骨缺损,动物模型,实验。检索时限为2000-01-01/2022-08-01。结果与结论:①对入选的27篇随机对照动物实验进行了分析和评估,实验动物包含大鼠、小鼠、新西兰兔及羊,骨缺损类型主要包含圆柱形骨缺损和节段性截骨骨缺损,部位以股骨中段及远端居多。多用于评估骨修复材料、药物、载药活性物质及物理治疗等方法对骨缺损修复的影响及缺损愈合机制研究,尤其是负重骨缺损修复机制的研究。②不同缺损类型及不同实验动物股骨骨缺损值的范围不同,研究者可结合实验目的,选择合适的动物及骨缺损类型,并设置合理的骨缺损值。③目前的研究表明,股骨骨缺损模型以圆柱形及节段截骨骨缺损为主,主要是在股骨远端及中段,手术方法及术后处理较为成熟,可操作性强,能够提供成熟的实验动物模型。④就圆柱形骨缺损而言,大鼠及新西兰兔更适合,而节段性截骨则无特殊要求,各种动物均能满足实验要求。

膜诱导技术结合Ca(OH)_(2)-PMMA治疗节段性骨缺损的研究进展

节段性骨缺损是一种负担较大、治疗具有挑战性的疾病,其病因包括创伤、感染、肿瘤等。目前骨缺损的重建方法主要有血管化骨移植、骨搬运以及膜诱导技术(Masquelet技术)等。而血管化自体骨移植虽然被认为是重建大尺寸骨缺损的金标准,但其具有专业性要求高、治疗周期长、过程复杂等局限性,而膜诱导技术因简单、高效及可靠等特性被广泛应用于骨缺损的治疗。膜诱导技术通过两次手术获取具有生物效应的诱导膜,促进缺损部位新骨的生长和愈合,是目前国内外公认的治疗节段性骨缺损的有效方法。本文将概述骨缺损的现状,介绍临界尺寸骨缺损的概念,探讨及思考在膜诱导技术中结合聚甲基丙烯酸甲酯氢氧化钙混合物[Ca(OH)_(2)-PMMA]新型材料应用于节段性骨缺损治疗的临床意义。

基于工程临界分析法的相控阵超声检测焊缝缺陷定量研究

本文分析了相控阵超声检测对缺陷定量的特点,介绍了相控阵超声采用工程临界分析法(ECA)对缺陷定量的特殊性。通过多种检测方法对焊缝中预制缺陷进行检测和分析,发现采用工程临界分析法定量不仅能合理地分析评定缺陷,还能保证检测结果一致。得出相控阵超声检测采用工程临界分析法对缺陷定量既科学合理,又准确可靠。

胶原基骨、天然煅烧骨在大鼠颅骨缺损修复术中的诱导成骨效果对比观察

目的对比观察胶原基骨和天然煅烧骨在大鼠颅骨缺损修复术中的诱导成骨效果。方法18只SD大鼠随机分为3组,每组6只,均建立SD大鼠颅骨双侧临界尺寸骨缺损模型,均行缺损修复术,术中颅骨一侧缺损部位填充胶原基骨(胶原基骨组),另一侧缺损部位填充天然煅烧骨(煅烧骨组)。术后第4、8、12周,取大鼠颅骨双侧缺损部位新生的骨组织,通过Micro-CT方法及病理检查结果评价成骨效果[成骨速度(新生骨骨体积分数、新生骨骨面积分数)、成骨质量(骨小梁数量、厚度、间隙;新生骨组织中纤维结缔组织、新生毛细血管数量)],并比较。结果Micro-CT结果显示,术后第4、8、12周,胶原基骨组的新生骨骨体积分数、骨小梁数量、骨小梁厚度均高于天然煅烧骨组,骨小梁间隙低于煅烧骨组。HE染色结果显示,术后第4、8、12周,与煅烧骨组比较,胶原基骨组的新生骨骨面积分数高。胶原基骨组胶原基骨吸收速度快,新生骨含较多的结缔组织、新生血管,骨质较软;煅烧骨组天然煅烧骨吸收速度慢,新生骨中结缔组织、血管较少,骨质偏硬。结论在大鼠颅骨临界尺寸骨缺损修复术中,胶原基骨诱导成骨的速度较快,成骨量高,吸收快,新生骨组织中结缔组织、新生血管多,新生骨质类似“松质骨”;天然煅烧骨诱导成骨速度较慢,新生骨组织中结缔组织、新生血管少,新生骨质类似“皮质骨”。

Determining the critical size of a rabbit rib segmental bone defect model

In order to establish and standardize the rabbit rib segmental bone defect model,it is of vital importance to determine rabbit rib critical size defect(CSD).According to the general time needed for spontaneous long-bone regeneration,three-month observation period was set to determine the CSD.The rabbit rib segmental bone defects with different sizes from 1 to 5cm with or without periosteum were performed in the eighth rib of 4-month-old male New Zealand rabbits and underwent Xray examinations at the 4th,8th and 12th weeks postoperatively.The gross and histological examinations at postoperative week 12 were evaluated,which showed that the critical sizes in the rabbit rib models with and without periosteum were 5 and 2 cm,respectively.This study provides prerequisite data for establishing rabbit rib CSD model and evaluating bonematerials using this model.

Oxygen generating scaffolds regenerate critical size bone defects

Recent innovations in bone tissue engineering have introduced biomaterials that generate oxygen to substitute vasculature.This strategy provides the immediate oxygen required for tissue viability and graft maturation.Here we demonstrate a novel oxygen-generating tissue scaffold with predictable oxygen release kinetics and modular material properties.These hydrogel scaffolds were reinforced with microparticles comprised of emulsified calcium peroxide(CaO_(2))within polycaprolactone(PCL).The alterations of the assembled materials produced constructs within 5±0.81 kPa to 34±0.9 kPa in mechanical strength.The mass swelling ratios varied between 11%and 25%.Our in vitro and in vivo results revealed consistent tissue viability,metabolic activity,and osteogenic differentiation over two weeks.The optimized in vitro cell culture system remained stable at pH 8-9.The in vivo rodent models demonstrated that these scaffolds support a 70 mm^(3) bone volume that was comparable to the native bone and yielded over 90%regeneration in critical size cranial defects.Furthermore,the in vivo bone remodeling and vascularization results were validated by tartrate-resistant acid phosphatase(TRAP)and vascular endothelial growth factor(VEGF)staining.The promising results of this work are translatable to a repertoire of regenerative medicine applications including advancement and expansion of bone substitutes and disease models.

颌骨临界缺损动物模型在颌骨缺损修复中的应用

背景:颌骨缺损修复一直是口腔颌面外科具有挑战性的难题之一。人工骨材料逐渐取代自体骨及同种异体骨成为颌骨缺损修复的研究热点。为评价人工骨材料作为颌骨缺损修复替代物的发展前景,有必要建立可重复且有效的颌骨缺损动物模型,但目前尚无统一的理想实验动物颌骨缺损模型能完美地模拟人类颌骨结构和力学特征。目的:从建立模型的动物种类及其优缺点、建模动物年龄的选择、实验动物颌骨临界缺损大小的选择、手术入路及手术部位的选择、建模后实验检测方法等方面对颌骨缺损动物模型进行综述。方法:检索CNKI和Pub Med等中英文数据库,中文检索词为“颌骨、下颌骨、临界大小缺损、动物模型”,英文检索词为“jaw、mandibular、critical-sized defect、animal model”。纳入与颌骨缺损及其动物模型的实验研究及进展情况相关性高的68篇文献进行归纳总结。结果与结论:(1)建立理想颌骨缺损动物模型并确立颌骨临界大小缺损对于颌骨缺损的修复机制或验证生物材料对骨缺损的修复效果具有重要作用。(2)统计发现大鼠、犬、猪的下颌骨已建立合理临界缺损动物模型,目前国内外关于兔颌骨节段性和非节段性缺损模型的临界大小缺损尚未达成共识。使用羊或灵长类动物作为颌骨缺损动物模型的研究很少,以往研究中建立的模型可为羊或灵长类动物颌骨临界大小缺损的确立提供一定的理论基础。(3)提示对于不同物种的颌骨缺损动物模型的规范化建立以及确立颌骨临界大小缺损用于颌骨缺损修复的机制和应用尚待深入研究。

兔下颌骨临界骨缺损人工材料植入实验动物模型的建立

目的建立兔下颌骨临界骨缺损人工材料植入的动物模型。方法选用30只健康成年日本大耳白兔,雌雄各半,在双侧下颌骨体部分别制造13mm×6mm的矩形全层临界骨缺损,左侧植入实验材料泡沫状碳化硅(SiC),右侧植入羟基磷灰石(HA)作自身对照,予以适当的术后护理,待取材观察。结果1只动物因麻醉意外死亡,1只因拒食术后1个月死亡,另有2只因术前分别有感冒和腹泻症状,分别于术后1d和2d死亡。其余26只动物在术后4,8,12,24周均能正常进食,创口未见感染征象,健康状况良好。结论本实验运用的建立兔下颌骨临界骨缺损人工材料植入实验动物模型的方法是可行的。

骨基质明胶与羟基磷灰石修复兔桡骨缺损模型的对照研究

目的 比较骨基质明胶 (BMG)与羟基磷灰石 (HAC)在节段性骨缺损愈合上的差别。方法 把 16只新西兰大白兔的双侧桡骨制造成 10mm的骨缺损模型 ,分别植入BMG、自体骨段和HAC及旷置。在术后即刻 ,2、4和 8周进行放射学、组织学、扫描电镜和骨密度的检测。结果 发现BMG组术后 4周即有新骨形成 ,8周缺损已愈合 ;组织学发现植入BMG的缺损处为多中心成骨 ,术后 8周已基本吸收 ,而植入HAC的骨缺损处也可见到缺损愈合 ,但HAC没有降解。结论 治疗兔桡骨缺损模型上 ,BMG和自体骨有相近的疗效 ,并优于在体内吸收较差的HAC。

含缺陷陶瓷材料的强度

含缺陷材料强度不仅与缺陷的形状、尺寸有关，而且还与材料脆性相关的破坏发生区的大小有关。由此推导了含各种缺陷材料的强度方程，计算了不影响材料强度的临界缺陷尺寸。提出含裂纹材料的强度曲线σＤ＝σｔ（Δ／ａ）１２／２．２为强度下限，因此将裂纹、破坏发生区与强度等三者的关系图推荐为材料强度图。最后，用含有各种人工缺陷的Ｓｉ３Ｎ４试样进行了验证实验。

基于缺陷概率特点的粉末冶金材料寿命预测概率模型

粉末冶金材料由于其制造工艺的特点,强度和寿命对微缺陷(夹杂、气孔、表面划伤)十分敏感,导致了粉末冶金材料的破坏具有较大的分散性,使得寿命预测更为困难.本文根据国内粉末材料中缺陷的分布特点,基于文献[7～9]中概率断裂分析的思路,对原有方法进行了修正和推广,重新给出了缺陷在表面、亚表面以及内部时的定义及缺陷在这些不同位置时出现概率断裂的确定方法,建立了一个可考虑缺陷形状、大小、位置等分布特征的粉末冶金材料寿命预测概率模型,并基于此计算了不同尺寸缺陷位于不同位置时材料的失效概率及总失效概率.分析表明:所给出的方法可以很好的表征国内工艺条件下粉末冶金材料缺陷的概率特征对强度寿命的影响,方法是有效的.

bFGF-胶原蛋白缓释系统促进兔下颌骨缺损修复的研究

目的观察评估bFGF-胶原蛋白缓释系统作为骨修复材料的可能性。方法 60只日本大耳白兔随机分成3组:bFGF胶原海绵组,胶原海绵组及空白对照组。手术建立兔双侧下颌骨洞穿性骨缺损模型并植入相应生物材料。分别在2、6、8、12周对造模部位取材,行大体观察、CT影像学检测和组织学观察。结果大体观察和CT影像学检测显示实验组骨创愈合速度较快。组织学观察可见实验组成骨情况优于同期对照组,胶原蛋白在体内作用时间持续至6周以前,其持续释放的bFGF颗粒对骨缺损修复有明显的促进作用,但发挥作用时间主要在12周前。结论 bFGF-胶原蛋白缓释系统对兔下颌骨缺损具有良好的修复效果,其发挥作用时间主要在骨缺损修复早期。此外,胶原蛋白海绵本身对骨缺损修复早期亦具有一定促进作用。

基于缺陷分布形式的粉末冶金涡轮盘可靠度计算模型

为研究微缺陷对粉末冶金涡轮盘可靠性的影响,在有限元分析结果的基础上,基于国内粉末盘中缺陷分布的概率特点,建立针对低循环疲劳裂纹萌生和裂纹扩展失效模式的可靠度计算模型。该模型可计算不同缺陷分布形式、不同循环载荷条件下的轮盘可靠度。对某型粉末盘失效概率的分析表明:表面质量是导致粉末盘失效的重要因素,这同大量试验研究结果相一致,对粉末盘的设计和使用具有工程指导意义。

载辛伐他汀PLGA/CPC支架材料复合BMSCs修复大鼠颅骨缺损的实验研究

目的:探讨载辛伐他汀PLGA/CPC支架材料复合骨髓间充质干细胞(BMSCs)构建组织工程骨,修复大鼠颅骨临界尺寸骨缺损的可行性以及效果。方法:24只雄性大鼠随机均分为3组;在大鼠颅骨人字缝两侧各做一直径5mm的骨缺损。每组16个骨缺损再随机分为:载辛伐他汀PLGA/CPC/BMSCs(Brdu标记的BMSCs)组(n=4);载辛伐他汀PLGA/CPC组(n=4);单纯PLGA/CPC组(n=4)以及空白对照组(n=4)。术后4、8、12周取标本分别进行大体观察,HE染色及免疫组织化学染色来评价骨再生情况。结果:术后4、8、12周组织学观察表明载辛伐他汀PLGA/CPC/BMSCs组的成骨质量和速度明显优于其他3组,免疫组化结果显示载辛伐他汀PLGA/CPC/BMSCs组骨钙素(OC)阳性表达IOD值明显高于其他3组。结论:载辛伐他汀PLGA/CPC支架材料复合BMSCs可以诱导大鼠颅骨临界尺寸骨缺损内的新骨形成,成骨质量优于其他3组,而且可以明显缩短骨愈合时间。

干细胞因子在大鼠下颌骨缺损修复中的表达研究

目的:探讨在SD大鼠下颌骨临界性骨缺损(critical size bone defect,CSD)与自愈性骨缺损修复过程中,各时相点干细胞因子(stem cell factor,SCF)的表达情况。方法:①分别在36只SD大鼠双侧下颌骨的下颌角部制造临界性骨缺损(直径5 mm)和自愈性骨缺损(直径2 mm)模型,实验动物分为6组,在术后第1、3、5、7、14、21天分别处死;②利用免疫组织化学方法检测骨缺损区各时相点SCF的表达情况;③利用Western印迹法检测骨缺损区各时相点SCF存在与否,并进行半定量分析。结果:成功构建了大鼠双侧下颌骨的临界性骨缺损和自愈性骨缺损模型。免疫组织化学结果显示,骨缺损愈合的各时相点SCF均有较高的表达,但SCF在临界性骨缺损组各时相点的表达,均低于自愈性骨缺损组。结论:SCF在骨缺损修复中发挥重要的作用。