天然组织工程皮肤支架材料的分类及其免疫原性研究现状

组织工程皮肤是组织工程研究最为成熟的一个领域,其核心内容是构建一种支持细胞生长的三维支架,与角质形成细胞和／或成纤维细胞进行体外复合培养,形成可用于创面覆盖与修复的皮肤等同物。其中支架材料为种子细胞提供了黏附、迁移、增生和分化的空间环境,在组织工程皮肤的构建中起着重要作用。组织工程皮肤支架材料包括人工合成组织工程皮肤支架材料（简称人工合成支架材料）和天然组织工程皮肤支架材料（简称天然支架材料）两大类。     

新生小牛皮肤的形态学和生物力学特点及脱细胞方法探索

目的通过新生小牛与成人皮肤组织在形态学和生物力学性能方面的对比研究,寻找临床应用牛真皮基质的可能证据,并初步探索对牛真皮组织进行脱细胞处理的方法。方法收集新生小牛和成人背部全层皮肤标本,采用大体观察、HE染色、Masson三色染色、天狼猩红染色、Gomori醛复红染色、扫描电镜和透射电镜的方法,显微照相后进行形态学观察和图像分析软件的测量;采用力学生物材料试验机检测皮肤的力学性能。采用胰蛋白酶与去污剂的不同浓度和时间组合方式对牛真皮组织进行脱细胞处理,初步观察其脱细胞效果。结果新生小牛与人的皮肤比较,真皮和表皮的厚度均明显变薄,两者的比值显著减小;真皮内Ⅰ型和Ⅲ型胶原纤维分别较人真皮增多和减少,但真皮胶原纤维束的间隙率[(41.72±1.81)∶(40.66±1.40),P=0.467]和胶原纤维束粗细[(11.28±0.18)μm∶(10.88±0.66)μm,P=0.368]差异却没有统计学意义。扫描电镜观察可见新生牛真皮胶纤维束与人真皮胶原纤维束均较纤细,排列疏松,且有一定的孔隙分布;透射电镜显示新生牛真皮胶原原纤维横纹周期长度较人真皮短,但两者的胶原原纤维直径显著差异。生物力学检测示新生牛皮肤最大应力[(21.08±0.91)MPa]和杨氏模量[(82.12±1.23)MPa]均要明显高于人皮肤的最大应力[(12.76±1.60)MPa,P=0.001]和杨氏模量[(48.63±5.50)MPa,P=0.001],而最大应变却明显低于人真皮[(0.51±0.002)mm∶(0.75±0.028)mm,P=0.001]。脱细胞方法探索显示随着胰酶浓度的增加、处理时间的延长,新生牛真皮基质内细胞核成分越来越少,但对真皮胶原结构的破坏也越来越大。结论新生牛皮肤虽然在表皮与真皮厚度、真皮胶原类型比例以及生物力学上与人皮肤有明显差异,但真皮的胶原纤维束三维结构两者之间存在较大相似性。适当浓度和时间的胰蛋白酶组合可制备出空间结构和脱细胞效果较为理想的新生牛脱细胞真皮基质,为修复人体软组织缺损提供有应用前景的生物材料。     

颗粒状脱细胞真皮基质的形态学特征及理化性能体外研究

目的 研究颗粒状脱细胞真皮基质(particulate acellular dermal matrix,PADM)的体外形态学特征与理化性能.方法 收集SD大鼠背部皮肤样本,采用本实验室的脱细胞方法制备片状脱细胞真皮基质(acellular dermal matrix,ADM)并分析其内胞核和DNA残留情况.将片状AD...     

渗透冲击联合超声和去污剂处理对新生牛真皮组织学和生物活性成分的影响

目的采用渗透冲击联合超声和去污剂处理新生牛真皮,观察处理前后新生牛真皮基质的组织学和生物活性成分的变化。方法从8头健康雄性新生牛皮肤获取网状层真皮组织。采用反复渗透压改变、超声震荡和去污剂联合法对新生牛网状层真皮进行处理,HE染色、DAPI染色和核酸电泳检测细胞成分残留情况;扫描电镜(SEM)观察胶原束结构和细胞成分;PicoGreen法、DMMB法和BCA法对脱细胞前后真皮基质的DNA、sGAG和蛋白质含量进行定量分析;ELISA法测定脱细胞前后真皮基质内TGF-β1、EGF、bFGF和KGF含量。结果形态学观察可见脱细胞处理后的真皮三维结构完整,胶原纤维束排列较疏松,细胞清除较彻底,未见明显细胞及细胞碎片残留。与脱细胞处理前比较,脱细胞处理后的DNA含量[(2 516.1±324.2)ng/mg vs(249.5±53.8)ng/mg,P=0.000)]、sGAG含量[(5.92±0.50)μg/mg vs(2.48±0.24)μg/mg,P=0.000]、TGF-β1含量[(478.8±196.1)pg/g vs(180.3±111.0)pg/g,P=0.009]和EGF含量[(10.52±2.78)pg/g vs未能检测到EGF含量]均明显减少;而bFGF含量[(788.6±333.8)pg/g vs(364.8±294.8)pg/g,P=0.424]下降了53.7%,KGF含量[(0.033±0.000)pg/g vs(0.033±0.000)pg/g,P=0.433]变化不显著。结论反复渗透冲击联合超声和去污剂处理对新生牛真皮基质明显地清除了细胞及细胞碎片,较好地保留了真皮细胞外基质的三维结构和主要生物活性成分。     

巴马小型猪与人真皮的组织形态学和生物力学基本特征比较研究

目的通过比较研究巴马小型猪与人皮肤在真皮组织结构、胶原类型和生物力学性能方面的差异,寻找猪脱细胞真皮基质临床应用受限相关的组织结构及生物力学原因。方法收集巴马小型猪与人的背部全层皮肤样本,采用大体观察、HE染色、Masson三色染色、天狼猩红染色、VVG染色、扫描电镜及透射电镜等方法,显微照相后进行形态学观察和图像分析软件测量,同时利用材料试验机检测真皮生物力学性能。结果与人皮肤比较,光镜下可见巴马小型猪皮肤的真皮胶原纤维束更粗[(39.29±10.17)μmvs(17.21±5.20)μm](P=0.000 3),而其间隙率更低[(19.01±1.55)%vs(32.36±1.28)%](P=0.029);真皮弹性纤维分布、Ⅰ型和Ⅲ型胶原含量及其比值也与人真皮有明显差异(P<0.05);扫描电镜显示巴马小型猪真皮的胶原纤维束排列紧密、束间孔隙小,透射电镜显示巴马小型猪真皮的胶原原纤维较细,横纹的周期更长;生物力学检测显示巴马小型猪真皮的最大应变[(0.52±0.05)mm/mm]低于人真皮[(0.80±0.06)mm/mm](P=0.003),而弹性模量[(69.65±12.16)MPa]和最大应力[(20...     

人角质形成细胞复合异种脱细胞真皮基质三维培养的形态学观察

Objective To establish the tridimensional culture method for tissue-engineered skin to observe the histomorphological change in human immortal KC strain (HacaT)cocultured with xenogenic acel-lular dermal matrix (ADM). Methods The ADM was prepared from SD rats by a modified method. HaCaTs were cultured in defined KC-serum free medium. HaCaTs in log growth phase were inoculated on ADM at the cell density of 2 × 105/cm2. They were submergedly cultured for 5 days and then changed to air-liquid phase culture for another 5 days. ADM and growth of HaCaTs on day 1 and 5 after cocultured with ADM were observed with scanning electron microscope. The histological change in ADM and HaCaTs on day 1, 5, and 10 after cocultured with ADM were examined by HE staining. Results The gross appearance of ADM was white with smooth and soft texture, and intact collagen bundles without cellular residue. HaCaTs adhered and stretched out pseudopodia on the surface of the ADM on day 1 after combined culture, and a monolayer of cells was formed on day 5, growing into 3 - 6 layers of cells on day 10 with a tendency to grow into ADM. Conclusions SD rats ADM is benefit for the adhesion of HaCaTs and the permeation of nutri-ent solution, from which an engineered multiple-layered human skin can be obtained within 10 days.     

人角质形成细胞基因导入效率的影响因素研究

目的 了解不同大小质粒和不同基因转染法对人KC基因导入效率的影响.方法 采用脂质体转染法、阳离子多聚物转染法、电穿孔联合细胞核转染试剂转染法、慢病毒感染法,分别将不同大小的质粒[pSUPER-增强型绿色荧光蛋白(EGFP)、pEGFP-N2、pHSER-绿色荧光蛋白(GFP)、ploxP-EGFP]导入人永生化KC株HaCaT细胞和人胚肾细胞株293FT细胞(后者为对照).于倒置荧光显微镜下观察GFP的表达,计算转染率.结果 (1)采用脂质体转染法可将4种质粒导入HaCaT细胞(转染率1.0%～3.3%)及293FT细胞(转染率80.0%～84.7%).(2)阳离子多聚物转染法亦可将4种质粒导入HaCaT细胞(转染率为1.0%～3.7%)和293FT细胞(转染率81.3%～86.7%).(3)采用电穿孔联合细胞核转染试剂转染法,可以将2种较小片段质粒pSUPER-EGFP和pEGFP-N2导入HaCaT细胞,转染率分别为22.3%和19.0%;而2种较大片段质粒pHSER-GFP和ploxP-EGFP的转染率分别为4.0%和3.3%.(4)pHSER-GFP经慢病毒包装后,导入HaCaT细胞的转染率高达97.0%,明显优于前3种转染法.结论 脂质体转染法、阳离子多聚物转染法较难将外源性基因导入人KC,慢病毒感染法的转染率明显优于电穿孔联合细胞核转染试剂转染法;不同大小质粒对转染率有明显影响.     

CCL20基因敲低型组织工程皮肤种子细胞的克隆筛选及其干扰效果

目的 采用重组慢病毒CCL20基因特异性shRNA载体感染人永生化角质形成细胞系(HaCaT),筛选出稳定干扰CCL20基因表达的细胞克隆并检测其干扰效果.方法 用CaCl2法将已构建好的3种pHSER-CCL20-shRNA-GFP载体(pHCG-1和pHCG-2为CC120基因特异性,pHCG-3为CCL20基因错配)转染293FT包装出慢病毒颗粒,流式细胞术测定其病毒滴度.用G418压力筛选慢病毒感染的HaCaT,荧光定量RT-PCR和ELISA法分别检测CC120基因mRNA和蛋白的表达水平,以判断其特异性干扰效果.结果 三种慢病毒载体所包装出的慢病毒滴度分别为7.08×105转导单位(TU)/ml、1.88×105TU/ml和2.08×105TU/ml;感染后的HaCaT经过G418筛选5～8周,获得4株CCL20基因特异性的细胞克隆(HaCaT-1、HaCaT-2、HaCaT-3和HaCaT-4)及2株CCL20基因错配对照的细胞克隆(HaCaT-5和HaCaT-6).经荧光定量PCR和ELISA法检测显示,4株CCL20基因特异性细胞克隆均具有稳定干扰效果,不仅能显著地下调CCL20基因的mRNA表达(其抑制率分别为81.0%、89.0%、81.3%、77.2%),而且明显地减少CCL20蛋白分泌(其抑制率分别为70.0%、86.1%、88.1%、90.7%).结论 采用重组慢病毒CCL20基因特异性shRNA载体感染HaCaT可以筛选出具有长期稳定表达RNA干扰效应的CCL20基因敲低型人永生化角质形成细胞克隆,将可能为低免疫排斥反应异基因组织工程皮肤的构建提供种子细胞.     

异体颗粒状脱细胞真皮基质与自体刃厚皮复合移植修复大鼠皮肤缺损创面效果观察

目的 观察异体颗粒状脱细胞真皮基质(PADM)与自体刃厚皮复合移植修复大鼠皮肤缺损创面的效果.方法 采用随机数字表法将12只SD大鼠分为实验组和对照组,每组6只.于2组大鼠背部制作全层皮肤缺损创面,实验组创面复合移植SD大鼠异体PADM(扩张比10:5)及厚度0.20 mm的自体刃厚皮,对照组创面仅移植厚度0.20 mm自体刃厚皮.术后2周起打开敷料观察大鼠创面愈合情况.术后2、3、4、6、8、12、20周计算2组创面移植皮片成活率、收缩率(或扩张率).术后20周取2组创周正常皮肤及创面皮肤标本,采用HE染色法观察胶原纤维束结构,测量胶原纤维束直径和间隙率;用天狼星红染色法观察Ⅰ、Ⅲ型胶原分布情况,测量Ⅰ、Ⅲ型胶原含量及其比值.对实验数据行独立样本t检验、Levene检验、t'检验.结果 (1)术后2周,实验组大鼠创面移植皮片成活率[(76.1±13.1)%]低于对照组[(94.5±1.3)%,t'=3.440,P=0.018].术后3周,实验组创面移植皮片收缩率[(34±8)%]明显大于对照组[(16±12)%,t=-3.211,P=0.009];术后8周,2组移植皮片扩张率接近一致.(2)HE染色和天狼星红染色显示,与大鼠创周正常皮肤比较,对照组移植皮片胶原纤维束呈均质化改变,胶原纤维纤细,排列紊乱;实验组移植皮片胶原纤维束结构、排列更接近创周正常皮肤,可见未完全降解的PADM.与对照组创面皮肤胶原纤维束直径[(7.3±1.4)μm]、间隙率[(17±4)%]、Ⅰ型胶原含量[(68.1±8.4)%]、Ⅲ型胶原含量[(32.0±8.4)%]以及Ⅰ、Ⅲ型胶原比例(2.3±1.0)比较,实验组胶原纤维束更粗[(9.6±0.8)μm,t=-3.562,P=0.005],间隙率更大[(24±5)%,t=-2.760,P=0.020],Ⅰ型胶原含量更高[(80.2±5.4)%,t=-2.981,P=0.014],Ⅲ型胶原含量更低[(19.8±5.4)%,t=2.981,P=0.014],Ⅰ、Ⅲ型胶原比例更高(4.3±1.2,t=-3.204,P=0.009).实验组创面皮肤上述胶原相关指标更接近于创周正常皮肤水平.结论 异体PADM在体内作为真皮再生模板,有助于改善自体刃厚皮所修复的大鼠皮肤缺损创面中真皮胶原纤维束的结构,提高再生真皮组织的成熟度.

Abstract：

Objective To evaluate the effects of mixed grafting of allogeneic PADM and autologous STS on wound healing of full-thickness defect in rats. Methods Full-thickness defects with size of 6 cm×4 cm were produced on the back of 12 SD rats, and they were divided into E group(n =6) and C group ( n = 6) according to the random number table. The wounds in E group were grafted with a mix of allogeneic PADM (expansion rate 10: 5) and autologous STS with thickness of 0.2 mm, while those in C group were grafted with autologous STS in the same thickness. The wound healing rate, survival rate, contraction rate,and expansion rate of transplanted skin were observed at post operation week (POW) 2, 3, 4, 6, 8, 12,20. Tissue samples form wounds and surrounding normal skin were harvested at POW 20 for histopathological observation as follows. The structure of collagen fiber bundle was observed by HE staining, the diameter and gap rate of collagen fiber bundle were also measured. The distribution of type Ⅰ and Ⅲ collagen was observed by sirsus red staining, and the contents of type Ⅰ , Ⅲ collagen and their ratio were also examined.Data were processed with independent samples t test, Levene test, and t' test. Results Survial rate of transplanted skin in E group at POW 2 [(76. 1 ± 13. 1)%] was obviously lower than that in C group [(94.5 ± 1.3)%, t' =3.440, P =0.018]. Contraction rate of transplanted skin in E, C groups at POW 3 showed significant difference [(34±8)%vs. (16 ±12)%, t = -3.211, P =0.009]. Compared with those in peri-wound normal skin, collagen fiber bundles in C group showed signs of homogenization, and collagen fibers were thin with irregular arrangement. Collagen fiber structure and arrangement of composite skin in E group were similar to those surrounding normal skin with incomplete degradation of PADM. Diameter of collagen fiber bundle [( 9.6 ± 0.8) μm] , gap rate between collagen bundle [( 24±5) %] , content of type Ⅰ collagen [( 80.2 ± 5.4) %] and the ratio of typeⅠto type Ⅲ collagen(4.3 ± 1.2) in E group were all increased as compared with those inC group [(7.3±1.4) μm (t = -3.562, P =0.005), (17±4)%( t =-2.760, P =0.020), (68.1 ±8.4)%(t = -2.981, P =0.014), 2.3±1.0(t = -3.204, P =0. 009)], while content of type Ⅲ collagen [( 19.8 ± 5.4) %] in E group was lower than that in C group [(32.0 ±8.4)% , t = 2. 981, P = 0. 014]. Above-mentioned indexes of collagen in wound of E group were similar to those of normal skin surrounding the wound. Conclusions Allogeneic PADM used as dermal regeneration template is beneficial in improving collagen fiber bundle structure in dermis layer of rats with fullthickness skin wounds when repaired with autologous STS, and it accelerates maturation of regenerative dermal tissue.