纳米仿生组织工程血管兔腹主动脉置换术后体内演化的实验研究

EXPERIMENTAL STUDY ON EVOLUTION OF NANO-BIOMIMETIC TISSUE ENGINEERED BLOOD VESSEL AFTER ABDOMINAL AORTA TRANSPLANTATION IN RABBITS

目的兔自体种子细胞构建的纳米仿生组织工程血管(nano-biomimetic tissue engineered blood vessel,NBTEBV)移植置换兔腹主动脉,观察NBTEBV在兔体内降解和重塑演化过程,检测NBTEBV的组织相容性。方法6月龄新西兰大白兔20只,雌雄不限,体重2～3kg。取兔自体种子细胞体外构建NBTEBV。取新西兰大白兔,游离肾下腹主动脉结扎其分支,剪下长约10mm腹主动脉,采用同体种子细胞来源的NBTEBV置换兔腹主动脉,吻合口置钛夹标记。观察NBTEBV在兔体内降解及重塑演化过程;术后第12周行DSA检查及彩色多普勒检查;术后第1、4、12周,取移植血管行大体及组织学观察,并行移植血管14C标记的PLGAX射线电子能谱检测。结果17只兔移植NBTEBV在观察期内保持通畅,3只兔分别于术后36、72h死于移植段腹主动脉闭塞。术后第12周DSA检查示移植血管显影良好,彩色多普勒检查示移植血管通畅,血流为层流,血流速度未见异常,无血管扩张。术后第1周移植血管腔被覆单层内皮细胞,管壁平滑肌细胞分布层次欠清晰,周围较多仿ECM夹杂未降解的黑色PLGA;术后第4周管壁平滑肌细胞分层,ECM开始形成,仿ECM成分部分降解,PLGA含量明显减少,颜色减淡;术后第12周管壁分层更清晰,ECM已形成,仿ECM成分完全降解,几乎无PLGA,血管形态近似自体血管。14C标记的PLGA射线电子能谱检测示14C能量峰值逐周递减。结论构建的NBTEBV有较好的手术操作性,同体移植术后具备良好组织相容性,在动物体内的自然重塑演化过程符合组织工程技术要求,电纺构建NBTEBV是可行的。

Objective To develop an experimental model of abdominal aorta transplantation with nano-biomimetic tissue engineered blood vessel （NBTEBV） and to investige the change of histomorphology in evolutionary process of degradation and remodeling. Methods Twenty 6-month-old New Zealand rabbits were included, weighing 2-3 kg, male or female. The autologous seed cells of rabbits were harvested to build NBTEBV in vitro. After the branch of abdominal aorta under kidney was ligated, about 10 mm abdominal aorta was cut and replaced by NBTEBV; the anastomotic stoma was marked by Ti clips. NBTEBV＇s evolutionary processes of degradation and rebuilding were observed. Twelve weeks after operation, DSA and color Doppler examinations were made. At 1, 4 and 12 weeks after operation, the gross and histological observations were made and 1^14C binding in PLGA was detected with X-ray photon spectroscopy. Results Of 20 rabbits, 17 showed that the NBTEBV was patency; 3 died from NBTEBV occlusion 36 or 72 hours after operation. The results of DAS and color Doppler showed the blood flow was patency, the blood flow rate was normal and there was no angiectasis. The lumen of transplanted blood vessel was covered with monolayer endothelial cells. At 1 week, smooth muscle cells （SMCs） arranged regularly and much PLGA distributed in the EMCs. At 4 weeks, SMCs arranged in a layer, ECM was forming, mimic ECM degraded partly; PLGA decreased obviously. At 12 weeks, the SMCs arranged regularly, ECM formed, mimic ECM degraded, no PLGA was seen in the wall, the shape of graft was similar to the natural vessel. The decreasing crest value of ^14C in specimen showed the degradation of PLGA. Conclusion NBTEBV has a good surgical maneuverability and histocompatibility, its remodeling evolutionary process fits in with tissue engineering specification. Building NBTEBV with ELSP is feasible.