不同方法处理的牛心包生物相容性和钙化结果分析

目的 观察脱细胞处理对牛心包体内生物相容性及钙化的影响并与戊二醛处理的牛心包进行比较；材料和方法对新鲜牛心包随机分为三组，A、戊二醛处理组：新鲜牛心包采用0．5％的戊二醛进行处理；B、新鲜牛心包组：新鲜牛心包保存于四联抗生素液中；C、脱细胞组：新鲜牛心包酶．去污剂联合脱细胞后保存于四联抗生素液中。上述处理后的牛心包经细菌培养，显示无细菌生长后，植入雄性昆明小鼠皮下三周观察炎性浸润及钙化情况。采用von Kossa钙染色检查进行定性分析；原子吸收光谱检查进行钙含量定量分析。同时体外对三组牛心包进行力学和热皱缩温度进行测试。结果 三组间炎性浸润程度明显不同，0．5％的戊二醛处理组钙化程度明显增高，每克干重牛心包平均含钙量71．2mg，较其他两组有明显差异（P〈0．001），新鲜牛心包组（平均2．12mg／g干重）和脱细胞组（1．41mg／g干重）间钙化程度方面亦有显著统计学意义（P〈0．001）。组织学钙染色光镜下检查显示三组间黑色颗粒有明显差异，支持三组间钙含量定量结果的差异。戊二醛处理组的力学性能与优于新鲜组和脱细胞处理组，热皱缩温度高于新鲜组和脱细胞处理组。结论 新鲜牛心包脱细胞处理后钙化显著降低，免疫源性降低，有很好的生物相容性。     

AngⅡ诱导大鼠BMSCs联合脱细胞牛心包体外构建工程化心肌组织的实验研究

目的：探讨血管紧张素Ⅱ（AngⅡ）诱导骨髓间充质干细胞（BMSCs）分化为心肌细胞的能力,及诱导后BMSCs体外联合脱细胞牛心包构建工程化组织心肌的可行性。方法分离培养大鼠BMSCs,用含0.1μmol/L AngⅡ的完全培养基诱导培养第3代BMSCs 24 h,然后换用完全培养基连续培养;对照组采用完全培养基连续培养。采用免疫荧光法检测诱导后的BMSCs表达心肌特异蛋白cTnT、β-MHC情况;透射电镜观察诱导后的细胞超微结构。用去污剂-酶消化法对新鲜牛心包行脱细胞处理,然后将诱导后4周的BMSCs接种于脱细胞牛心包生物支架上培养3 d后,对其进行观察检测。结果 AngⅡ诱导后的BMSCs向心肌细胞分化,可表达cTnT和β-MHC,对照组则不表达cTnT和β-MHC。电镜结果显示诱导后的细胞间可见类肌节组织及明显的桥粒连接;新鲜的牛心包经去污剂-酶联合四步法脱细胞处理及京尼平交联后,HE染色观察脱细胞的效率接近100%。扫描电镜观察发现脱细胞处理后的牛心包表面无细胞残留且表面排列杂乱,放大后可见有2μm小孔。观察体外构建的工程化心肌显示诱导后的BMSCs可良好地黏附于脱细胞牛心包生物支架表面并生长增殖,且少量可渗透到支架内部。结论 AngⅡ诱导的大鼠BMSCs可向心肌细胞方向分化,表达心肌特异蛋白cTnT和β-MHC。将其种植于脱细胞牛心包生物支架上,表面黏附良好,且可渗透到支架内部及血管周围,有望用于构建具有血管网络化的组织工程化心肌。     

牛心包脱细胞支架的制备研究

组织工程支架材料是构建组织工程器官或组织的重要基础,天然脱细胞基质由于具有其优良特性而成为理想的支架材料。本研究采用胰酶去污剂法、冻融去污剂24 h法、冻融去污剂48 h法、冻融核酸酶法和去污剂核酸酶法等5种方法对牛心包组织进行脱细胞处理。通过HE染色、扫描电镜观察、含水量检测、力学检测、DNA含量检测和细胞毒性试验,判断不同脱细胞方法的脱细胞效果及其对牛心包基质的影响,从而筛选出对牛心包进行脱细胞的最佳方法。结果显示冻融后去污剂24 h法可以完全脱除牛心包的细胞成分,同时细胞外基质和力学特性保持完好,细胞毒性低,且经济实惠,是制备牛心包脱细胞支架的较好方法。     

生物交联剂京尼平交联牛心包生物支架材料的性能

脱细胞牛心包膜因其具有优良特性而成为组织工程生物瓣膜中理想的支架材料.采用冻融+表面活性剂法对牛心包组织进行脱细胞处理后,用戊二醛或京尼平对其进行表面修饰固定.通过HE染色及扫描电镜观察脱细胞效果,并对交联组织进行厚度检测、含水量和接触角测试、力学检测、交联指数和差示扫描量热(DSC)测定、体外降解、溶血试验以及细胞毒性试验,判断两种交联方法对脱细胞牛心包基质的影响,从而选择出交联脱细胞组织的最好方法.结果显示,冻融+表面活性剂法脱除细胞彻底,戊二醛或京尼平交联后组织厚度明显增加分别约20%,25%,亲水性良好,力学特性稳定,交联指数都高达90%,且28 d降解率分别为5%和3%,交联后组织稳定性高.但京尼平组溶血率(0.37%)远小于戊二醛组溶血率(13.77%),且细胞毒性很低.作为瓣膜组织工程支架材料,京尼平交联脱细胞牛心包膜比戊二醛交联效果具有更好生物相容性,交联效果好,是较好的交联方法.     

深低温处理对异种骨-髌腱-骨移植排斥反应的影响

目的： 观察深低温处理对异种骨-髌腱-骨（BPB）移植排斥反应的影响。方法：采用大鼠股部肌袋模型法探讨深低温处理对异种BPB移植免疫反应的影响,通过观察外周血T细胞活化和植入物组织形态学变化情况来判定免疫反应程度。结果：新鲜未处理异种BPB移植后3 d CD4+/CD8+细胞CD25+表达率即显著升高,与自体移植组比较有显著差异（P<0.05）,术后14 d达高峰,且维持该峰值至术后35 d仍无下降;深低温处理的异种BPB移植后CD4+/CD8+细胞CD25+的表达明显受到抑制,表达时间推迟,至术后14 d才有轻度升高,术后3 d起各时点与未处理组比较,均P<0.05。组织学检查发现,深低温处理组骨、腱组织周围见少量淋巴细胞浸润,但未侵入组织内,无组织坏死,腱束结构清楚,胶原排列规则;新鲜异种移植组可见大量斑片状淋巴细胞弥漫性浸润骨及胶原组织周围及其中,可见骨碎片,腱结构不清,胶原排列紊乱,部分切片可见较多的嗜酸性粒细胞和多核巨细胞等炎症细胞。结论：深低温处理能显著降低异种BPB免疫原性,抑制排斥反应发生。     

大鼠骨髓间充质干细胞体外心肌定向诱导及心肌组织构建研究

目的探讨大鼠骨髓间充质干细胞（BMSCs）向心肌定向诱导分化及诱导后BMSCs体外构建工程化心肌组织的可行性。方法用含10μmol／L5-氮胞苷（5-Aza）的完全培养液（LG-DMEM,10％胎牛血清,100U／mL青霉素,100μg／mL链霉素,10μg／L碱性成纤维细胞生长因子）孵育第3代BMSCs24h后改用完全培养基培养4周,采用未处理组作为阴性对照。采用免疫细胞化学方法检测心肌肌钙蛋白T（cTnT）、α-肌动蛋白（α-Actin）的表达;逆转录-聚合酶链反应（RT-PCR）检测早期心肌形成转录因子GATA-4、Nkx2．5、TDGF-1基因的表达。将已诱导4周的BMSCs接种于多聚赖氨酸包被的脱细胞牛心包生物支架上培养2周后检测。结果诱导组细胞向心肌细胞转化,表达cTnT、α-Actin,对照组不表达cTnT、α-Actin;RT-PCR检测BMSCs诱导后表达早期心肌形成转录因子GATA-4、Nkx2．5、TDGF-1等基因;诱导后的BMSCs黏附于脱细胞牛心包生物支架表面,生长良好。结论大鼠BMSCs可向心肌细胞定向诱导分化,与脱细胞牛心包生物支架黏附良好,有望构建理想的组织工程化心肌。     

新鲜羊膜与脱细胞羊膜修复腱鞘缺损预防肌腱粘连北大核心

背景:羊膜独有的结构可阻止某些物质通过,能保证包裹内组织正常营养供应,而且具有抗粘连、组织相容性好、炎性反应轻、纤维包裹少及可降解等特性。目的:比较新鲜羊膜及脱细胞羊膜修复腱鞘缺损,预防肌腱粘连和促进肌腱愈合的作用。方法:取60只雄性来亨鸡,制作双足第三足趾制备肌腱及腱鞘损伤模型,随机分为3组修复,新鲜羊膜组采用新鲜人羊膜修复腱鞘缺损,脱细胞羊膜组采用人脱细胞羊膜修复腱鞘缺损,对照组不做腱鞘修复。修复后进行第三足趾组织学观察及生物力学测试。结果与结论:①组织学观察:修复后2周,3组均存在充血水肿及炎症反应,新鲜羊膜组最轻,对照组最严重,3组水肿及炎症反应随时间延长逐渐减轻。修复12周,各组假鞘较修复后4周明显成熟,新鲜羊膜组及脱细胞羊膜组假鞘表面细胞致密层状排列整齐,表面光滑;对照组假鞘表面细胞排列紊乱,结构松散,可见表面纤维组织突出假鞘表面;②生物力学测试:脱细胞羊膜组、新鲜羊膜组修复后4,8,12周的肌腱滑动距离均大于对照组(P<0.05),前2组间比较差异无显著性意义;脱细胞羊膜组、新鲜羊膜组修复后4,8周的肌腱最大拉伸断裂强度高于对照组(P<0.05),且新鲜羊膜组高于脱细胞羊膜组(P<0.05),3组修复后12周的肌腱最大拉伸断裂强度无差异;③结果表明:新鲜羊膜和脱细胞羊膜均可用于重建腱鞘缺损,预防肌腱粘连,新鲜羊膜在促进早期肌腱愈合方面优于脱细胞羊膜。     

灭菌处理牛心包制备脱细胞支架的内皮化

文题释义：组织工程：主要研究种子细胞、生物材料、构建组织和器官4个方向,其核心是建立由细胞和生物材料构成的三维空间复合体,对病损组织进行形态、结构和功能的重建并达到永久性替代,具有良好的发展前景和广阔的应用市场。牛心包脱细胞支架：经化学和物理方法去除牛心包中的细胞,形成无免疫原性或低免疫原性材料,构建组织工程支架。 背景：组织工程学研究常用的动物组织不可避免地存在各种微生物附着,而无菌是组织工程材料临床应用的一项基本要求。 目的：观察体积分数75%乙醇灭菌对牛心包性能及生物相容性的影响。方法：将牛心包组织分别用无菌PBS(对照组)、含1%抗生素(青霉素/链霉素/两性霉素B溶液)的PBS、氯己定及体积分数75%乙醇进行灭菌处理。采用LB固体培养基评价4种方法的杀菌效果;采用VB染色评估4组处理对牛心包组织结构的影响;通过CCK-8实验测定4种处理抽提液的细胞毒性。将体积分数75%乙醇灭菌处理的牛心包制作为脱细胞支架,与人脐静脉内皮细胞共培养,观察细胞的黏附与内皮化效果。结果与结论：①体积分数75%乙醇和氯己定处理24 h的牛心包满足完全灭菌的要求,1%抗生素处理组和对照组可见明显菌落形成;②VB染色显示,体积分数75%乙醇、氯己定和1%抗生素处理的牛心包胶原纤维呈波浪状排列整齐,结构紧凑,弹性纤维含量较少但结构清晰;③体积分数75%乙醇灭菌处理的牛心包不影响L929细胞的增殖活性,培养1-3 d内的细胞存活率均在100%以上;氯己定灭菌处理的牛心包有很强的细胞毒性,导致细胞死亡;④人脐静脉内皮细胞可在脱细胞支架表面正常生长与黏附;在20 d的种植期内,第8-12天脱细胞支架表面黏附的细胞最多;⑤结果说明,体积分数75%乙醇能够有效消灭附着在牛心包上的所有微生物,不会影响牛心包的组织学完整性与生物相容性。ORCID: 0000-0002-3448-8230(刘飞) 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     

不同蛋白涂层在脱细胞牛心包片上对骨髓间充质细胞黏附生长的影响

为观察和评价不同蛋白涂层对骨髓间充质细胞在脱细胞牛心包片上黏附生长的影响,采用酶消化结合去污剂洗涤法制作脱细胞牛心包片,在其表面用不同蛋白(纤维连接蛋白、明胶蛋白、型胶原蛋白)均匀涂层。提取并培养大鼠骨髓间充质细胞,将其接种到预涂层的牛心包片上,未涂层组作为对照。在不同时间点采用Hochest染色观察细胞贴附生长情况,48h采用MTT法定量分析。纤维连接蛋白涂层及明胶蛋白涂层与型胶原蛋白涂层和不涂层组相比,对骨髓间充质细胞贴附增殖能力均有显著提高(P<0.001);纤维连接蛋白涂层和明胶蛋白涂层之间(P>0.05)以及型胶原蛋白涂层和不涂层对照组之间(P>0.05)对细胞的贴附生长没有显著差异。结果表明:脱细胞牛心包片上纤维连接蛋白涂层及明胶蛋白涂层能明显提高骨髓间充质细胞的贴附增殖能力,而型胶原蛋白涂层对骨髓间充质细胞的贴附增殖没有明显的改善。     

脱细胞基质软骨支架的制备

背景：脱细胞基质材料去除了天然材料中的细胞成分,保留了基质成分,有效降低了天然材料的免疫原性,同时能够保持材料的机械强度。 目的：拟利用洗脱方法去除兔肋软骨中的细胞基质,制备天然生物支架材料。 方法：取新西兰大白兔肋软骨,清除周围组织后随机分组处理,以未经处理的肋软骨作为正常对照组;48 h处理组以去污剂-酶化学消化48 h;96 h处理组以去污剂-酶化学消化96 h,3组均通过苏木精-伊红染色及电镜观察脱细胞效果。同时收集诱导第7天的兔骨髓间充质干细胞3×109 L-1,与同种异体肋软骨脱细胞基质体外复合培养,于第3,7天取复合物行电镜观察细胞在脱细胞基质表面的黏附生长情况。 结果与结论：新鲜肋软骨标本每个软骨陷窝内均有排列紧密的二三个软骨细胞,去污剂-酶化学消化后软骨陷窝内的细胞逐渐脱失,至消化处理96 h后,软骨陷窝内的细胞完全脱失。共培养第3天时,脱细胞基质表面有大量骨髓间充质干细胞分布,细胞为多角形,有伪足伸出,锚定在基质表面,部分区域可见细胞在基质表面增殖分裂;第7天时,脱细胞基质表面大部分均为细胞覆盖,细胞呈扁平状,有多个足突充分伸展,细胞之间互相连接,分泌大量细胞外基质沉积在基质表面,呈冰霜样改变,表明制备的脱细胞基质具有良好的细胞相容性。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;组织工程全文链接：     

Study on the Preparation of Decellularized Scaffold of Bovine Pericardium

Objective: To search for the best procedure on preparation of acellular bovine pericardium,so to provide scaffolds for constructing tissue-engineering Methods:The bovine pericardiums were treated with 5 methods,which were divided into 6 groups.Group A:Fresh bovinepericardium;GroupB:Trypsin-detergentgroup;GroupC:Freeze-thaw-detergent24 h group;Group D:.Freeze-thaw-detergent 48 h group;Group E:Freeze-thaw-nuclease group;Group F:Detergent-nuclease group.Then,by HE staining and scanning electron microscope to observe the effects of decellularization and fibrous changes among the 6 groups;by water content testingmechanical testing to observe the changes in physical properties of the matrix;by detecting the DNA content of each group to determine the effect of decellularization qualitatively;by cytotoxicity test to detect the biocompatibility of bovine pericardium in each group.Results:The 5 methods can all remove the cellular components effectively,compared with the fresh bovine pericardium,the water content of each decellularized group were increased (P＜0.05),while the DNA content decreased (P＜0.05),with statistically significant differences.Of group E,the fibers were a little disorder,with the largest tension and the elastic modulus increased,while the rupture tensile rate decreased.Compared with fresh bovine pericardium,the largest tension of the other decellularization groups were all decreased (P＜0.05).The fibers of group B,group D were irregularly arranged and also with ruptures,both the elastic modulus and the rupture tensile rate decreased(P＜0.05).In group C and F,the fibers were dense and their direction was normal,the elastic modulus and the rupture tensile rate were similar to the fresh bovine pericardium (P＞0.05).Cytotoxicity results showed that the cell toxicity of group B,group C,group D,group E and group F were respectively 0.9,0.6,1.0,1.0 and 0.5,each group were qualified toxicity test,in which group C and group F were with the lowest cytotoxicity.Conclusion:Group C and group F can remove the cell components of bovine pericardium successfully,while maintaining the major structural components and the histological and biological properties of bovine pericardium,and with low cytotoxicity.However,group C is more economical than group F,and easier to operate.So the method on freeze-thaw-detergent 24 h can be the best choice to produce a decellularized bovine pericardium.     

Short duration gluteraldehyde cross linking of decellularized bovine pericardium improves biological response

Gluteraldehyde stabilized bovine pericardium is used for clinical application since 1970s because of its desirable features such as less immunogenicity and acceptable durability. However, a propensity for calcification and long term implant failure is reported because of gluteraldehyde treatment. There is also failure of implant to integrate into host tissue because of its resistance to tissue remodeling. Decellularized bovine pericardium, a potential alternative allows tissue remodeling but it has problems such as immunogenicity and chronic inflammatory response. In this study, decellularized bovine pericardium was subjected to short duration, low concentration gluteraldehyde cross-linking at two levels and its biological response (both in vitro and in vivo) was compared with un-crosslinked decellularized bovine pericardium and fully crosslinked normal bovine pericardium. It was observed that both un-crosslinked and partially crosslinked decellularized bovine pericardium to be non-cytotoxic and it caused significantly less inflammatory cytokine release such as TNF alpha and IL1beta from activated macrophages. Among all groups, short duration 0.2% Gluteraldehyde treated decellularized bovine pericardium showed significantly less antibody response and inflammatory response compared to un-crosslinked decellularized pericardium, short duration 0.6% gluteraldehyde treated decellularized bovine pericardium or completely cross linked bovine pericardium in juvenile rat subcutaneous implantation model. Moreover, short duration 0.2% gluteraldehyde crosslinked decellularized bovine pericardium showed minimum calcification, better host fibroblast incorporation, new collagen deposition and angiogenesis within the implant. These attributes may finally lead to better implant remodeling and sustained implant function during clinical use.     

Preseeding of human vascular cells in decellularized bovine pericardium scaffold for tissue-engineered heart valve: an in vitro and in vivo feasibility study

Human vascular cells from saphenous veins have been used for cell seeding on the synthetic scaffolds for constructing tissue-engineered heart valve (TEHV). However, little is known about the seeding of human vascular cells on bovine pericardium, a potential natural scaffold for TEHV. This study was aimed to assess the basic in vitro and in vivo characteristics of the human vascular cells seeded on decellularized bovine pericardium. In vitro, bovine pericardium samples with cell seeding were inspected on day 7, 14, and 21 by histology, scanning electron microscopy, and immunohistochemistry. In vivo, experiments were performed in nude mice by bilateral dorsal incision for the implantation of decellularized bovine pericardium with and without cell seeding. Results demonstrated that a total of 8-10 × 10(6) cells were obtained within 4-5 wk by the primary co-culture, which were detected positive for von Willebrand factor, α-smooth muscle actin antibodies, and fibronectin, indicating the presence of endothelial cells, smooth muscle cells, and fibroblasts, respectively. In vitro, the seeded cells showed a steady increase of endothelial activity from day 1 to day 7 and remained stable until day 21. After 30 days of implantation in vivo, the cells on the decellularized bovine pericardium could differentiate directionally and show all the identities of human endothelial cells, smooth muscle cells, and fibroblasts. These results indicate that the human vascular cells from the saphenous vein are an optional cell source for seeding on decellularized bovine pericardium scaffold for constructing TEHV.     

纳米银－猪脱细胞真皮基质敷料治疗浅Ⅱ度烧伤创面的临床观察

目的观察纳米银－猪脱细胞真皮基质敷料在临床上治疗浅Ⅱ度烧伤创面的临床疗效。 方法2014年1月到2015年12月,选取北京军区总医院烧伤整形科收治的浅Ⅱ度烧伤患者90例,按入院顺序依次编码,采用随机排列数字表法将90例患者分为纳米银敷料组、猪脱细胞真皮基质敷料组及纳米银－猪脱细胞真皮基质敷料组,每组30例。患者入院当天,拍照计算创面面积,并用咽拭子取创面分泌物作细菌培养,行创面清创术,分别在创面上敷以纳米银敷料、猪脱细胞真皮基质敷料以及纳米银－猪脱细胞真皮基质敷料。于治疗后第5天,用咽拭子取创面分泌物作细菌培养;采用痛觉评分标准,通过询问与观察患者换药时的痛觉情况,评估患者换药时痛觉评分。于治疗后第7天,拍照计算创面面积,计算创面愈合率。记录创面最终愈合时间。数据比较采用单因素方差分析、χ²检验及SNK－q检验。 结果纳米银敷料组、猪脱细胞真皮基质敷料组及纳米银－猪脱细胞真皮基质敷料组在治疗后第5天创面细菌培养阳性数结果分别为2例(6.6%)、9例(30.0%)、1例(3.3%),3组结果比较,差异有统计学意义(χ²＝10.962,P＝0.004);纳米银－猪脱细胞真皮基质敷料组的细菌培养阳性数结果显著优于猪脱细胞真皮基质敷料组,差异有统计学意义(χ²＝7.680,P＝0.006)。纳米银敷料组、猪脱细胞真皮基质敷料组及纳米银－猪脱细胞真皮基质敷料组治疗后第5天的痛觉评分[(8.6±0.5)、(6.6±0.8)、(0.6±1.3)分],治疗后第7天的创面愈合率[(61.67±18.22)%、(86.77±15.32)%、(99.80±0.56)%],创面愈合时间[(11.5±1.3)、(10.3±0.7)、(7.3±0.7)d],组间差异均有统计学意义差异(F＝201.7、19.9、55.7,P值均小于0.05);纳米银－猪脱细胞真皮基质敷料组治疗后第5天的痛觉评分显著低于其余两组,差异均有统计学意义(P值均小于0.05);治疗后第7天的创面愈合率明显优于其余两组,差异均有统计学意义(P值均小于0.05);创面愈合时间显著短于其余两组,比较差异均有统计学意义(P值均小于0.05)。 结论纳米银－猪脱细胞真皮基质敷料具有抗感染、促进创面愈合及减轻换药痛觉的作用。     

牛肌腱冻干脱细胞支架的生物力学特性

背景：目前的脱细胞方法在去除细胞的同时对细胞外基质存在一定的损伤,降低了脱细胞支架的生物力学性能。 目的：分析冻干牛肌腱脱细胞支架的生物力学特性。 方法：取新鲜小牛趾伸屈肌腱,去除小牛肌腱表面的滑膜、腱膜及软组织,双蒸水冲洗干净后低压冻干,通过物理方法制备肌腱纤维束60个,随机均分为两组,实验组于无菌操作下置入丝氨酸蛋白酶抑制剂,室温下持续24 h,无菌PBS冲洗后,再移入低浓度胰酶+乙醇混合溶液中,在不破坏细胞外基质的情况下去除细胞壁,室温下持续5 h,再将纤维束移入脱氧核糖核酸酶溶液中持续5 h,最后将已完成脱细胞步骤的支架使用PBS冲洗48 h,无菌室内室温下干燥;对照组不做处置。检测两组材料的弹性模量、耐久性及最大应力。 结果与结论：两组耐久性相似,但实验组在相同位移处的应力小于对照组;两组弹性模量比较差异无显著性意义,但实验组最大应力低于对照组(P < 0.01)。说明冻干脱细胞支架能够在一定程度上模仿牛肌腱的生物力学功能。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     

Tissue engineering small-diameter vascular grafts: preparation of a biocompatible porcine ureteric scaffold

This study aimed to investigate a biocompatible, biomechanically functional, small-diameter (<6 mm) scaffold for tissue engineering a vascular graft using acellular porcine ureters. Porcine ureters were decellularized and sterilized using sequential treatment with hypotonic Tris buffer, sodium dodecyl sulphate 0.1% w/v (plus proteinase inhibitors), nuclease solution (RNase and DNase), and peracetic acid. The scaffold was compared with fresh ureter according to histology, immunocytochemistry, quantitative determination of alpha-galactosyl (alpha-Gal), and biochemistry. The biomechanical properties of the scaffold were compared with those of fresh ureters and human saphenous vein. The biocompatibility of decellularized ureters was assessed using in vitro contact and extract cytotoxicity tests. The in vivo biocompatibility was investigated using a mouse model. The histioarchitecture of the acellular ureteric scaffolds was preserved with some loss of basement membrane proteins while showing no evidence of cellularity. There was no evidence of residual alpha-Gal epitope present in acellular ureter. The ultimate tensile strength, compliance, and burst pressures of the acellular ureters were not compromised, compared with fresh tissues (p > 0.05), and the results compared favorably with fresh human saphenous vein samples (p > 0.05). The decellularized scaffolds were shown to be biocompatible with porcine smooth muscle and endothelial cells in vitro. One month after subcutaneous implantation in mice, explants were analyzed immunohistochemically using anti-CD3, Factor VIII, F4/80 (macrophage), and alpha-smooth muscle actin antibodies. The fresh tissue controls had a significantly thicker capsule (of inflammatory cells and fibrous tissue) than decellularized implants (p < 0.05). Decellularized explants were infiltrated with a combination of fibroblast-like cells and macrophages, indicating a healthy repair process. This study has demonstrated the potential of acellular porcine ureteric scaffolds in tissue engineering small-diameter living vascular grafts.     

In vivo evaluation of cellular and acellular bovine pericardia fixed with a naturally occurring crosslinking agent (genipin)

A cell extraction process was employed in the study to remove the cellular components from bovine pericardium, leaving a framework of largely insoluble collagen and elastin. It was hypothesized in the literature that this process may decrease the antigenic load (or increase the biocompatibility) within the material. Additionally, acellular tissues may provide a natural microenvironment for host-cell migration to regenerate the tissue. The study was to evaluate the biocompatibility of cellular and acellular bovine pericardia fixed with a naturally occurring crosslinking agent (genipin) implanted subcutaneously in a growing rat model. Additionally, the tissue regeneration rate in the genipin-fixed acellular tissue was investigated. The glutaraldehyde-fixed counterparts were used as controls. The results indicated that the degrees in inflammatory reaction for the genipin-fixed cellular and acellular tissues were significantly less than their glutaraldehyde-fixed counterparts. Additionally, it was noted that the inflammatory reactions for the glutaraldehyde-fixed cellular and acellular tissues lasted much longer than their genipin-fixed counterparts. The tissue regeneration rate for the genipin-fixed acellular tissue was significantly faster than its glutaraldehyde-fixed counterpart. The calcium content of each studied group, analyzed by atomic absorption. did not change significantly until at the 52nd week, postoperatively. The differences in calcium content between the cellular and acellular tissues were insignificant for both the glutaraldehyde- and genipin-fixed groups throughout the entire course of the study. In summary, the biocompatibility of the genipin-fixed cellular and acellular tissues was superior to their glutaraldehyde-fixed counterparts. The genipin-fixed acellular tissue provided a better microenvironment for tissue regeneration than its glutaraldehyde-fixed counterpart, due to its low cytotoxicity. These results suggested that the genipin-fixed acellular tissue might be used as a tissue-engineering matrix in the clinical applications.     

Comparison of novel xenograft (bovine fetal growth plate) and allograft effects on experimental bone defect healing in rabbit

Large bone defects resulting from trauma, tumors, osteitis, implant loosening, or corrective osteotomies require surgical therapy because spontaneous regeneration is limited to relatively small defects. Currently, transplantation of autografts or allografts, mineral bone substitutes, and callus distraction are the most commonly used techniques for skeletal reconstruction. Each method has significant limitations, e.g., availability and biological or biomechanical reasons. This study was designed to evaluate allograft and new xenograft (bovine fetal growth plate) effects on the bone healing process. Twenty male New Zealand White rabbits were used in this study. In the allograft group, the defect was filled by fresh allogeneic cortical graft; in the xenograft group, the defect was filled by a segment of bovine fetal growth plate and was fixed by cerclage wire. Radiological, histopathological, and biomechanical evaluations were performed and results were scored and analyzed statistically. Statistical tests did not support significant differences between the two groups radiographically at the 14th postoperative day (P > 0.05). There was a significant difference in bone formation at the 28th, 42nd, and 56th postoperative days. There were significant radiological differences for bone union and remodeling by the 42nd day postoperatively (P < 0.05). The xenograft was superior to the allograft by the 56th postoperative day for radiological bone formation (P < 0.03); histopathological and biomechanical evaluation revealed no significant differences between the two groups. It can be concluded that the superior bone healing process in the xenograft group was due to the presence of some osteoinduction proteins in bovine fetal growth plate.