细胞外基质材料在骨组织工程中的研究进展

由疾病、外部创伤等原因引起的大骨骼缺损的治疗需要通过骨移植手术,寻找安全易得的替代骨已经成为临床上的重要课题,近年来快速发展的组织工程骨为解决这一难题提供了一种新的途径。支架材料作为组织工程的核心要素,其表面性状、结构,机械性能和生物学性能均能调控细胞的各种生命活动和体内组织的修复再生。细胞外基质由于其天然性、低免疫排斥性和优异的生物相容性等特点,已被广泛用作再生医学的支架材料。通过回顾近些年来细胞外基质材料在骨组织工程中的应用,阐述多种细胞外基质材料的构建修饰方法及其体外、体内的生物学效应,并对其在骨再生领域的应用前景进行展望。     

异体脱细胞真皮基质的研究进展

异体脱细胞真皮基质是天然真皮的脱细胞基质,经过冷冻干燥形成的三维支架结构。作为一种新兴的生物工程支架,它通过空间诱导和组织替代作用修复组织缺损。由于其源于人体正常组织,经临床应用证实,异体脱细胞真皮基质拥有优秀的组织相容性,现已广泛地应用于临床各科的创伤修复。     

异种细胞外基质的研究进展

细胞外基质因为其组织结构、成分及生物力学环境最适合种子细胞的生长发育及新陈代谢,材料可降解,因而成为国内外组织工程领域的研究热点,目前异体ECM临床应用较多,而异种ECM由于潜在的免疫风险及伦理因素等原因尚未广泛应用于临床。就异种ECM的制备、组织结构、免疫特点及其在医学各领域的临床应用等方面结合国内外研究进展进行综述。     

天然组织去细胞技术的研究进展

由细胞外基质(ECM)组成的生物支架材料通常从组织或器官去细胞衍生而来。经去细胞处理的组织和器官已广泛应用于组织工程和再生医学。最理想的去细胞技术是保存ECM完整的组成成分和三维超微结构,但所有的去细胞方法都会导致结构的破坏和组成成分潜在的丢失。从组织中有效地去除细胞依赖于来源的组织和所用的物理、化学和酶的试剂。这些处理影响ECM支架的生物化学组成、组织的超微结构和力学性能,进而影响宿主对支架材料的反应。最优的保存ECM支架完整性和生物活性的去细胞方法是在处理过程中对试剂和技术的使用作出正确的选择。本文总结并分类目前常用的去细胞方法和不同方法对生物支架的作用特点,并对最近提出的抗原去除策略做一综述。     

异体脱细胞真皮基质的研究进展

异体脱细胞真皮基质是天然真皮的脱细胞基质，经过冷冻干燥形成的三维支架结构。作为一种新兴的生物工程支架，它通过空间诱导和组织替代作用修复组织缺损。由于其源于人体正常组织，经临床应用证实，异体脱细胞真皮基质拥有优秀的组织相容性，现已广泛地应用于临床各科的创伤修复。     

骨组织工程人工合成高分子细胞外基质替代材料的研制

组织工程的出现为人类治疗骨缺损提供了一种新的选择。人工合成高分子材料及其与陶瓷材料的共混物具有可控的生物降解性、可调控的力学性能以及良好的加工性 ,是细胞外基质替代材料的理想选择     

脱细胞技术在组织工程血管中的应用进展

将天然血管经过脱细胞处理得到的脱细胞血管,被认为是一种具有广阔应用前景的组织工程血管支架材料.截至目前,细胞外基质(ECM)支架的制备方法仍缺乏统一标准.脱细胞方法的选择取决于组织来源和基质支架的用途,尤其对于脱细胞血管等需要长期承受血流冲击的基质支架材料来说,脱细胞方案的选择至关重要.细胞清除效率和细胞外基质支架的性...     

骨组织工程人工合成高分子细胞外基质替代材料所研制

组织工程的出现为人类治疗骨缺损提供了一种新的选择。人工合成高分子材料及其与陶产 共混物具有可控的生物降解性、可调控的力学性能以及良好的加工性，是细胞外基质替代材料的理想选择。     

异体脱细胞真皮基质作为组织工程皮肤真皮支架的可行性*

背景：组织工程皮肤是目前研究皮肤损伤修复重建的重要手段之一,异体脱细胞真皮基质不存在免疫原性,在异体移植时不会发生排斥反应,是比较理想的真皮替代物。 目的：观察异体脱细胞真皮基质的组织相容性。 方法：以正常人体真皮组织作为对照,通过体外、体内细胞毒性实验检测异体脱细胞真皮基质的组织相容性,以膨胀度、饱和含水量及生物力学分析检测异体脱细胞真皮基质的亲水性及机械性能。 结果与结论：真皮基质中未见任何细胞成分,其网孔直径介于100~180 μm 之间。脱细胞真皮基质组饱和含水量为(69.6±3.97)%,膨胀度2.30±0.42,最大断裂力为(3.082±0.046) N,与对照组相比,差异无显著性意义(P > 0.05)。体内外细胞毒性检测,未见明显细胞生长抑制及免疫排斥反应。提示异体脱细胞真皮基质机械性能接近正常皮肤,组织相容性好,免疫排斥反应小,是构建组织工程皮肤理想的真皮材料。     

内皮祖细胞复合血管无细胞基质替代输尿管的可行性

背景:临床治疗输尿管缺损,缺乏有效的输尿管替代物,而无细胞基质在体内单独作为支架,常引起替代段输尿管狭窄,但内皮祖细胞移植能改善缺血组织,参与血管新生。目的:初步探讨内皮祖细胞复合的血管无细胞基质替代输尿管的可行性。方法:将自体猪来源的内皮祖细胞以及平滑肌细胞一起种植在同种异体的颈动脉来源的血管无细胞基质中,体外孵育后进行猪长段输尿管的替代。结果与结论:移植后4周,无细胞基质替代物已经开始与输尿管融合,替代物内可以明显见到上皮细胞层,肌细胞层以及新生的血管。但在移除输尿管支架管后,也就是在移植后12周的替代物标本中,发现移植物的萎缩和管腔的明显狭窄,移植物周围出现严重的纤维化炎症反应。替代段上方输尿管明显扩张积水,同侧肾脏明显萎缩,而且已经失去功能。     

Comparison of three methods for the derivation of a biologic scaffold composed of adipose tissue extracellular matrix

Extracellular matrix (ECM)-based scaffold materials have been used successfully in both preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. Results of numerous studies have shown that ECM scaffolds are capable of supporting the growth and differentiation of multiple cell types in vitro and of acting as inductive templates for constructive tissue remodeling after implantation in vivo. Adipose tissue represents a potentially abundant source of ECM and may represent an ideal substrate for the growth and adipogenic differentiation of stem cells harvested from this tissue. Numerous studies have shown that the methods by which ECM scaffold materials are prepared have a dramatic effect upon both the biochemical and structural properties of the resultant ECM scaffold material as well as the ability of the material to support a positive tissue remodeling outcome after implantation. The objective of the present study was to characterize the adipose ECM material resulting from three methods of decellularization to determine the most effective method for the derivation of an adipose tissue ECM scaffold that was largely free of potentially immunogenic cellular content while retaining tissue-specific structural and functional components as well as the ability to support the growth and adipogenic differentiation of adipose-derived stem cells. The results show that each of the decellularization methods produced an adipose ECM scaffold that was distinct from both a structural and biochemical perspective, emphasizing the importance of the decellularization protocol used to produce adipose ECM scaffolds. Further, the results suggest that the adipose ECM scaffolds produced using the methods described herein are capable of supporting the maintenance and adipogenic differentiation of adipose-derived stem cells and may represent effective substrates for use in tissue engineering and regenerative medicine approaches to soft tissue reconstruction.     

Decellularization of bovine corneas for tissue engineering applications

Scaffolds derived from processed tissues offer viable alternatives to synthetic polymers as biological scaffolds for regenerative medicine. Tissue-derived scaffolds provide an extracellular matrix (ECM) as the starting material for wound healing and the functional reconstruction of tissues, offering a potentially valuable approach for the replacement of damaged or missing tissues. Additionally, acellular tissue may provide a natural microenvironment for host-cell migration and the induction of stem cell differentiation to contribute to tissue regeneration. There are a number of processing methods that aim to stabilize and provide an immunologically inert tissue scaffold. Furthermore, these tissue-processing methods can often be applied to xenogenic transplants because the essential components of the ECM are often maintained between species. In this study, we applied several tissue-processing protocols to the cornea in order to obtain a decellularized cornea matrix that maintained the clarity and mechanical properties of the native tissue. Histology, mechanical testing and electron microscopy techniques were used to assess the cell extraction process and the organization of the remaining ECM. In vitro cell seeding experiments confirmed the processed corneas’ biocompatibility.     

Mechanical properties and in vivo behavior of a biodegradable synthetic polymer microfiber-extracellular matrix hydrogel biohybrid scaffold

A biohybrid composite consisting of extracellular matrix (ECM) gel from porcine dermal tissue and biodegradable elastomeric fibers was generated and evaluated for soft tissue applications. ECM gel possesses attractive biocompatibility and bioactivity with weak mechanical properties and rapid degradation, while electrospun biodegradable poly(ester urethane)urea (PEUU) has good mechanical properties but limited cellular infiltration and tissue integration. A concurrent gel electrospray/polymer electrospinning method was employed to create ECM gel/PEUU fiber composites with attractive mechanical properties, including high flexibility and strength. Electron microscopy revealed a structure of interconnected fibrous layers embedded in ECM gel. Tensile mechanical properties could be tuned by altering the PEUU/ECM weight ratio. Scaffold tensile strengths for PEUU/ECM ratios of 67/33, 72/28 and 80/20 ranged from 80 to 187 kPa in the longitudinal axis (parallel to the collecting mandrel axis) and 41-91 kPa in the circumferential axis with 645-938% breaking strains. The 72/28 biohybrid composite and a control scaffold generated from electrospun PEUU alone were implanted into Lewis rats, replacing a full-thickness abdominal wall defect. At 4 wk, no infection or herniation was found at the implant site. Histological staining showed extensive cellular infiltration into the biohybrid scaffold with the newly developed tissue well integrated with the native periphery, while minimal cellular ingress into the electrospun PEUU scaffold was observed. Mechanical testing of explanted constructs showed evidence of substantial remodeling, with composite scaffolds adopting properties more comparable to the native abdominal wall. The described elastic biohybrid material imparts features of ECM gel bioactivity with PEUU strength and handling to provide a promising composite biomaterial for soft tissue repair and replacement.     

Ureteral segment replacement using an ovine fetal urachus duct (new xenogenic graft) in dogs

The ureter is an important part of the urinary system that can be affected by several disorders such as congenital malformations, extensive iatrogenic ureteral obstruction, ureteritis, retroperitoneal fibrosis, trauma, necrosis, calculi, tumors, etc. We wished to determine whether ovine fetal urachus duct will be accepted when used as a ureteral replacement material in other species. The ureters of five adult native dogs were approached through a ventral midline laparotomy incision. A segment of 3-cm midureter was resected unilaterally. The left ureteral segments were replaced with ovine fetal urachus duct using 5-0 PDS interrupted sutures. Internal ureteral catheter was left for 6 weeks. The patency of the ureters was assessed by intravenous pyelography at 2 and 8 weeks after the surgery, while inflammation and regeneration were assessed grossly and histologically. All five urachus transplantations were accepted successfully in radiological, macroscopical, and histological evaluation. The ovine fetal urachus seems to be an embryonic tissue of extremely low antigenicity and therefore suitable for transplantation.     

Decellularized extracellular matrix derived from human adipose tissue as a potential scaffold for allograft tissue engineering

Decellularized tissues composed of extracellular matrix (ECM) have been clinically used to support the regeneration of various human tissues and organs. Most decellularized tissues so far have been derived from animals or cadavers. Therefore, despite the many advantages of decellularized tissue, there are concerns about the potential for immunogenicity and the possible presence of infectious agents. Herein, we present a biomaterial composed of ECM derived from human adipose tissue, the most prevalent, expendable, and safely harvested tissue in the human body. The ECM was extracted by successive physical, chemical, and enzymatic treatments of human adipose tissue isolated by liposuction. Cellular components including nucleic acids were effectively removed without significant disruption of the morphology or structure of the ECM. Major ECM components were quantified, including acid/pepsin-soluble collagen, sulfated glycosaminoglycan (GAG), and soluble elastin. In an in vivo experiment using mice, the decellularized ECM graft exhibited good compatibility to surrounding tissues. Overall results suggest that the decellularized ECM containing biological and chemical cues of native human ECM could be an ideal scaffold material not only for autologous but also for allograft tissue engineering.     

Host protection against deliberate bacterial contamination of an extracellular matrix bioscaffold versus Dacron mesh in a dog model of orthopedic soft tissue repair

The resistance of two biomaterials, one synthetic and one biologic in origin, to deliberate bacterial infection was compared in a dog model of orthopedic soft tissue reconstruction. Twenty-four adult female dogs were randomly divided into two equal groups and a 2.0-cm-round full-thickness defect was created on the lateral surface of the stifle joint, leaving only the synovium and skin intact. The defect was surgically repaired with either Dacron trade mark mesh or a porcine derived extracellular matrix (ECM) scaffold material. The repair site was inoculated with 1 x 10(8) Staphylococcus aureus at the time of surgery and the dogs were survived for 28 days. Results showed a chronic pyogranulomatous inflammatory response at the Dacron trade mark implant sites versus a constructive tissue-remodeling response without residual inflammation at the ECM implant site. Three dogs in the group receiving the Dacron trade mark mesh were treated with Keflex trade mark (500 mg bid x 7 days) for signs of septicemia. A quantitative bacterial count of the implant sites at the time of sacrifice showed 6.52 x 10(5) +/- 1.2 x 10(6) and 6.5 x 10(2) +/- 1.8 x 10(3) bacteria per gram of tissue for the Dacron trade mark and ECM scaffold sites, respectively (P <.03). The ECM implant material was more resistant than the synthetic implant material to persistent infection following deliberate bacterial contamination and the ECM scaffold supported constructive tissue remodeling.     

Resurfacing potential of heterologous chondrocytes suspended in fibrin glue in large full-thickness defects of femoral articular cartilage: an experimental study in the goat.

A large full-thickness articular-cartilage defect was created in the medial femoral condyle of 32 adult goats. The defects were xenografted with isolated rabbit chondrocytes suspended in fibrin glue. Sham operated goats, where only a standardized defect was created, were used as controls. Results of cartilage repair were assessed after 3, 8, 13, 26 and 52 weeks. The repair tissue was evaluated macroscopically, histologically and biochemically. Results indicated that xenografted rabbit chondrocytes survived the transplantation and maintained their potential to produce matrix in fibrin glue, particularly if they were located in a non-weight-bearing area. In terms of an immunological reaction to xenografted chondrocytes, only mild signs of synovitis were observed in both groups and rejection of transplanted cells did not occur. From 3 weeks gradually progressive resolvement of the fibrin glue was observed with subsequent replacement by fibrous tissue. Initially xenografted defects histologically showed better tendency for cartilage regeneration, however, 52 weeks after surgery no significant differences could be detected in the repair tissue of both groups macroscopically, histologically and on biochemical scoring. The amount of collagen type II in the newly synthesized matrix was 75% 1 year after surgery. This study shows that isolated heterologous chondrocytes can be used for transplantation in articular cartilage defects, however, fibrin glue does not offer enough biomechanical support to the cells to maintain its function as a three-dimensional scaffold.     

Decellularization of tissues and organs

Decellularized tissues and organs have been successfully used in a variety of tissue engineering/regenerative medicine applications, and the decellularization methods used vary as widely as the tissues and organs of interest. The efficiency of cell removal from a tissue is dependent on the origin of the tissue and the specific physical, chemical, and enzymatic methods that are used. Each of these treatments affect the biochemical composition, tissue ultrastructure, and mechanical behavior of the remaining extracellular matrix (ECM) scaffold, which in turn, affect the host response to the material. Herein, the most commonly used decellularization methods are described, and consideration give to the effects of these methods upon the biologic scaffold material.     

骨髓基质干细胞复合纳米材料修复骨缺损的微循环研究

目的:了解骨髓基质干细胞(MSCs)复合纳米羟基磷灰石/聚乳酸(n-HA/PLA)构建组织工程骨修复骨缺损过程中,实验动物血液流变学和骨缺损修复区血流量的变化。方法:选择20只新西兰白兔,制作15mm长的桡骨节段性骨缺损模型,根据植入不同移植材料分为实验组和对照组,实验组于动物左侧桡骨缺损区植入组织工程骨,对照组植入n-HA/PLA,观察各组动物术后1h、7天、14天血液流变学指标和术后14天骨缺损修复区血流量的变化。结果:实验组与对照组比较,血液流变学指标和骨缺损修复区血流量差异显著。组织工程骨修复骨缺损,实验动物血液粘度降低,骨缺损修复区局部血流量增加。结论:与单纯n-HA/PLA材料比较,组织工程骨可促进骨缺损的修复。     

Preparation and characterization of decellularized tendon slices for tendon tissue engineering

To develop a naturally derived tendon tissue engineering scaffold with the preservation of the native ultrastructure, tensile strength, and biochemical composition of the tendon extracellular matrix (ECM), decellularized tendon slices (DTSs) were prepared using repetitive freeze/thaw of the intact Achilles tendons, frozen section, and nuclease treatment. The DTSs were characterized in the native ultrastructure, mechanical properties, biochemical composition, and cytocompatibility. Histological examination and DNA quantification analysis confirmed that cells were completely removed from tendon tissue by repetitive freeze/thaw in combination with nuclease treatment 12 h. The intrinsic ultrastructure of tendon tissue was well preserved based on scanning electron microscopy examination. The tensile strength of the DTSs was retained 85.62% of native tendon slice. More than 93% of proteoglycans (fibromodulin, biglycan) and growth factors (TGF-β1, IGF-1, VEGF, and CTGF) inherent in tendon ECM were preserved in the DTSs according to ELISA analysis. Furthermore, the DTSs facilitated attachment and repopulation of NIH-3T3 fibroblasts in vitro. Overall, the DTSs are sheet scaffolds with a combination of elemental mechanical strength and tendon ECM bioactive factors that may have many potential applications in tendon tissue engineering.