共价结合生长因子的胶原补片修补大鼠左心室室壁瘤的实验研究

Repair of left ventricular aneurysm secondary to myocardial infarction with cytokine-conjugated collagen scaffolds in rat models

目的比较采用碳化二亚胺法（EDC法）处理共价结合不同生长因子的胶原补片修补大鼠左心室室壁瘤后的再血管化情况，及其对大鼠左心功能的影响。方法直径5mm的圆形胶原补片经EDC法处理作对照组，再分别结合血管内皮细胞生长因子（VEGF）或VEGF＋碱性成纤维细胞生长因子（bFGF）后作实验组。成年雄性SD大鼠行左冠状动脉前降支结扎制作透壁心梗模型。4周后，心脏彩超筛选心梗面积占左心室前壁25％-35％者入选。随机分成3组，以不同补片行室壁瘤修补，对照组（8只），VEGF组（10只），VEGF＋bFGF组（10只）。术后1周、2周、4周分别行心脏彩超监测左心功能，至实验终点取材，免疫荧光法检测补片边缘毛细血管（vWFⅧ染色）及成熟血管（SMA染色）的生成情况。结果全组死亡比例15％（6／40只）。修补1周后，3组动物心功能均明显改善；4周后，结合生长因子的两组心功能较对照组明显改善（对照组对VEGF组，P〈0．05；对照组对VEGF＋bFGF组，P〈0．01）。组织学检查显示，两组结合有生长因子的毛细血管生成情况均较对照组明显改善（P〈0．05）；VEGF＋bFGF组的再血管化较其他两组明显改善（P〈0．01）。相关性分析显示，大鼠心功能参数（FS）与再血管化呈正相关（P=0．0297，r2=0．998）。结论EDC法可有效改善胶原补片的机械性能，共价结合生长因子后可显著增加补片内血管生成，再血管化有助于左心功能的维持。

Objective To compare the vascularization of collagen scaffolds with or without growth factors and their efficacy on cardiac function in postinfarcted rats underwent surgical ventricular restoration. Methods Collagen scaffolds were activated with 1-ethyl-3 -[ 3-dimethylaminopropyl ] carbodiimide hydrochloride chemistry （EDC） as control or continually covalently immobilized with vascular endothelial growth factor （VEGF） and VEGF ＋ basic fibroblast growth factor （bFGF） as experimental groups. Adult SD male rats underwent left anterior descending artery （LAD） ligation to generate transmural myocardial infarction（MI）. Four weeks later, by echocardiography, rats with moderate scar size （25% -35 % akinetie area of freedom wall of left ventricle） were screened out, assigned into 3 groups randomly and received the surgical ventricular restoration （SVR）. Then,cardiac function was measured by eehocardiography at lw, 2w and 4w after patch implantation. At endpoint of study （4w after patch implantation） , the rats were sacrificed and the hearts were harvested. Vascularization of patch were determined by capillary density （ evidenced by vWFⅧ staining） or mature vessel density （ evidenced by SMA staining） respectively. Results The general mortality of the animal model is 15% （6/40）. A significant improvement of cardiac function was observed in all animals at 1 w after patch implantation but that was better preserved in both cytokine-eonjugated groups 4w later （ control group vs. VEGF group, P 〈0. 05, control group vs. VEGF ＋ bFGF group,P 〈0. 01 ）. More capillaries were present in patch with growth factors （ P 〈 O. 05 ）, while significant functional vessel formation was observed only in VEGF ＋ bFGF group （ P 〈 0. 01 vs. control or VEGF group）. Additionally, we identified a positive correlation between heart function and ma- ture vessel density （ P = 0. 0297, r2 = 0. 998 ）. Conclusion The mechanical property of collagen scaffold can be effectively improved by EDC, the growth factors immobilized in scaffold were in favor of vascularization of patch, which may facilitate the preservation of cardiac function posterior to SVR.