含银异种脱细胞真皮基质的实验研究

目的了解含银异种脱细胞真皮基质(Xeno-ADM)的多项生物学性状,观察其移植效果。方法制备单纯xeno-ADM,再用2 g／L硝酸银浸泡,制成含银xeno-ADM。检测两种xeno-ADM对笔者单位烧伤患者创面常见菌的抑菌效果,并进行组织学观察;测量含银xeno-ADM的Ag+含量。在27只家兔背部制作全层皮肤缺损创面,分为A、B、C组,每组9只。A组移植自体刃厚皮,B组移植单纯xeno-ADM+自体刃厚皮,C组移植含银xeno-ADM+自体刃厚皮。术后2、4、6周取移植部位皮肤标本作形态学观察,并计算创面收缩率;术后2周计算移植皮片(未)成活率,并检测各组家兔淋巴细胞增殖活性。结果(1)含银xeno-ADM对创面常见菌的抑菌效果明显优于单纯xeno-ADM (P<0．05)。两种xeno-ADM中的表皮已完全除去,胶原纤维粗细均匀、排列规则、无明显变性,真皮中无细胞及细胞碎片。含银xeno-ADM的Ag+含量为(2．7±0．7)mg／g。(2)术后6周,A组家兔移植皮片呈暗红色,挛缩明显,易破溃,胶原纤维排列紊乱;B、C组移植皮片颜色接近周围正常皮肤,光滑无瘢痕,质地良好,胶原纤维排列有序,表皮-真皮连接结构和基底细胞桥粒、半桥粒结构以及基底膜重建明显。术后2、4、6周,A组家兔创面收缩率均明显高于B、C组(P<0．05);B、C两组创面收缩率相似(P>0．05)。术后2周,C组皮片完全成活率为91．7％,显著高于A组(77．8％)及B组(80．6％);3组家兔淋巴细胞增殖活性相似(P>0．05)。结论含银xeno-ADM脱除了基质中有免疫原性的细胞成分,保留了组织的基本结构和完整的胶原纤维支架,且具有较好的局部抗菌效果,不失为一种良好的真皮替代物。

Experimental study on xenogenic acellular dermal matrix incorporated with silver

OBJECTIVE: To investigate the biological characteristics of xenogenic acellular dermal matrix( Xeno-ADM) incorporated with silver, and to observe its effect in grafting. METHODS: Xeno-ADM was prepared with 0. 25% trypsin and 0. 5% tritonX-100 , and then it was immersed in 2 g/L silver nitrate solution to prepare xeno-ADM incorporated with silver. The bacterial inhibitory effect of two kinds of xeno-ADM on burn wound was determined, and the histological characteristic of the wounds was observed with optical microscope, transmission melectron microscope and scanning electron microscope. The Ag+ content in the xeno-ADM incorporated with silver was measured with atomic absorption spectrometer. Twenty-seven rabbits with full-thickness skin defects on the back were randomly divided into three groups, i. e. split-thickness skin autograft only( group A, n = 9) , xeno-ADM with overlying split-thickness skin autograft( group B, n = 9) , xeno-ADM incorporated with silver with overlying split-thickness skin autograft ( group C, n = 9). The skin specimens from grafted area in each group were harvested at 2,4 and 6 post-operation weeks( POW) and examined under light microscope and transmission electron microscope. The condition of the graft, the contraction degree of the grafts and the histogical changes in grafting area were observed at 2,4,6 POW. The survival rate of the grafts was calculated and the proliferative activity of the lymphocyte in each group was determined at 2 POW. RESULTS: 1. Compared with xeno-ADM, the anti-bacterial effect of xeno-ADM incorporated with silver was much better ( P < 0. 05). No epidermis was seen in both types of xenografts ,and the collagen fibers were even in size and arranged regularly, with no obvious degeneration, and the dermis was also devoid of cells and cellular components. The Ag + content in xeno-ADM incorporated with silver measured (2. 7+/-0. 7) mg/g. 2. The grafts in B and C groups presented similar color to that of normal skin at 6 POW, and it was smooth, with fine texture and no scarring. The collagen fibers was arranged regularly, and conjunction between epidermis and dermis, the structure of basal cell desmosome and semi-desmosome were well reconstructed. The grafts in A group was in dark red color, with obvious contraction, and easily broken. The contraction rate in A group at 2,4 and 6 POW were obviously higher than those in B and C groups( P < 0. 05), while no obvious difference was observed between B and C groups. ( P >0. 05). The overall survival rate of the grafts in C group at 2 POW was 91.7% , which was evidently higher than that in A (77.8%) and B (80. 6% ) groups. The lymphocyte proliferative activity exhibited no differece among A, B and C groups( P >0.05). CONCLUSION: The xeno-ADM incorporated with silver has good anti-bacterial effect. In addition, it preserves the basic tissue structure and integral collagen fiber scaffold, without cells to induce rejection, so that it can be used as an ideal dermal substitute.