Effects of transient receptor potential vanilloid type 4-specific activator on human vascular endothelial cell functions and blood supply of rat perforator flap and its mechanism
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摘要:目的 分析瞬时受体电位香草酸亚型4(TRPV4)激活对人脐静脉内皮细胞(HUVEC)功能及内皮-间质转化(EndMT)的作用,并探讨TRPV4激活对大鼠穿支皮瓣血流灌注和成活的影响及其机制。方法 采用实验研究方法。取第3~6代HUVEC进行实验,分为0.5 μmol/L 4α-佛波醇12,13-二癸酸酯(4αPDD)组、1.0 μmol/L 4αPDD组、3.0 μmol/L 4αPDD组、10.0 μmol/L 4αPDD组、磷酸盐缓冲液(PBS)组,分别采用相应终物质的量浓度的4αPDD及PBS培养,采用细胞计数试剂盒8(CCK-8)法检测培养6、12 h细胞增殖活性。另取细胞分为PBS组、1 μmol/L 4αPDD组、3 μmol/L 4αPDD组,同前处理并检测培养6、12、24、48 h的细胞增殖活性;采用划痕试验检测划痕后12、24、48 h剩余划痕面积,并计算剩余划痕面积百分比;采用Transwell实验检测培养24、48 h细胞迁移数量;采用成管实验检测培养4、8 h管状结构数量;采用蛋白质印迹法检测培养24 h细胞上皮钙黏素、神经钙黏素、Slug、Snail蛋白表达。体外实验每组各时间点样本数均为3。取36只8~10周龄雄性SD大鼠,按随机数字表法分为皮瓣延迟组、4αPDD组和生理盐水组,每组12只,均建立背部髂腰动脉穿支皮瓣模型。皮瓣延迟组大鼠仅于皮瓣移植术前1周行皮瓣延迟。4αPDD组和生理盐水组大鼠不行皮瓣延迟,在术前10 min及术后24、48 h,分别经腹腔注射4αPDD和等量的生理盐水。分别于术后0(即刻)、1、4、7 d,行大体观察并计算术后7 d的皮瓣成活率;于术后1、4、7 d,采用激光散斑对比成像技术检测皮瓣血流灌注;术后7 d,采用免疫组织化学染色法检测皮瓣闭塞血管区域微血管密度。体内实验每组各时间点样本数均为12。对数据行析因设计方差分析、重复测量方差分析、单因素方差分析、LSD-t检验、Bonferroni校正。结果 培养6、12 h,PBS组、0.5 μmol/L 4αPDD组、1.0 μmol/L 4αPDD组、3.0 μmol/L 4αPDD组、10.0 μmol/L 4αPDD组细胞增殖活性组间总体比较,差异均无统计学意义(P>0.05)。培养6、12、24、48 h,PBS组、1 μmol/L 4αPDD组、3 μmol/L 4αPDD组细胞增殖活性组间总体比较,差异均无统计学意义(P>0.05)。划痕后12 h,1 μmol/L 4αPDD组、3 μmol/L 4αPDD组细胞剩余划痕面积百分比均与PBS组相近(P>0.05);划痕后24、48 h,与PBS组比较,3 μmol/L 4αPDD组细胞剩余划痕面积百分比均明显降低(t值分别为2.83、2.79,P<0.05),1 μmol/L 4αPDD组细胞剩余划痕面积百分比均无明显变化(P>0.05)。培养24 h,1 μmol/L 4αPDD组、3 μmol/L 4αPDD组细胞迁移数量均与PBS组相近(P>0.05);培养48 h,1 μmol/L 4αPDD组、3 μmol/L 4αPDD组细胞迁移数量均明显多于PBS组(t值分别为6.20、9.59,P<0.01)。培养4 h,1 μmol/L 4αPDD组、3 μmol/L 4αPDD组细胞管状结构数量均明显多于PBS组(t值分别为4.68、4.95,P<0.05或P<0.01);培养8 h,1 μmol/L 4αPDD组、3 μmol/L 4αPDD组细胞管状结构数量均与PBS组相近(P>0.05)。培养24 h,与PBS组比较,3 μmol/L 4αPDD组细胞上皮钙黏素的蛋白表达明显降低(t=5.13,P<0.01),1 μmol/L 4αPDD组细胞上皮钙黏素的蛋白表达无明显变化(P>0.05);3 μmol/L 4αPDD组细胞神经钙黏素蛋白表达明显升高(t=4.93,P<0.01),1 μmol/L 4αPDD组细胞神经钙黏素的蛋白表达无明显变化(P>0.05);1 μmol/L 4αPDD组和3 μmol/L 4αPDD组细胞Slug的蛋白表达均明显升高(t值分别为3.85、6.52,P<0.05或P<0.01);3 μmol/L 4αPDD组细胞Snail的蛋白表达明显升高(t=4.08,P<0.05),1 μmol/L 4αPDD组细胞Snail的蛋白表达无明显变化(P>0.05)。1 μmol/L 4αPDD组和3 μmol/L 4αPDD组细胞上皮钙黏素、神经钙黏素、Slug、Snail的蛋白表达组间两两比较,差异均无统计学意义(P>0.05)。术后0 d,3组大鼠皮瓣一般情况均良好;术后1 d,3组大鼠皮瓣远端均出现青紫肿胀;术后4 d,3组大鼠皮瓣肿胀消退、远端变成暗褐色、发生坏死,其中生理盐水组大鼠皮瓣坏死面积比4αPDD组和皮瓣延迟组大;术后7 d,3组大鼠皮瓣坏死面积基本稳定,其中皮瓣延迟组大鼠皮瓣远端坏死面积最小。术后7 d,4αPDD组[(80±13)%]和皮瓣延迟组[(87±9)%]大鼠的皮瓣成活率相近(P>0.05)且均明显高于生理盐水组[(70±11)%,t值分别为2.24、3.65,P<0.05或P<0.01]。术后1 d,3组大鼠皮瓣整体血流信号基本一致,闭塞血管区域的血流信号均相对较强,远端均存在一定程度的灌注不足。术后4 d,3组大鼠皮瓣存活区与坏死区分界渐清晰,闭塞血管区域的血流信号增强,其中生理盐水组大鼠皮瓣远端低灌注区范围大于皮瓣延迟组和4αPDD组。术后7 d,3组大鼠皮瓣整体的血流信号基本稳定,其中皮瓣延迟组和4αPDD组大鼠皮瓣闭塞血管区域及整体血流信号强度均明显大于生理盐水组。术后7 d,4αPDD组和皮瓣延迟组大鼠皮瓣闭塞血管区域中的微血管密度相近(P>0.05)且均明显高于生理盐水组(t值分别为4.11、5.38,P<0.01)。结论 TRPV4激活后可能通过EndMT机制促进人血管内皮细胞的迁移和成管,从而增加穿支皮瓣的血流灌注、闭塞血管区域微血管密度,提高皮瓣成活率。Abstract:Objective To analyze the effects of transient receptor potential vanilloid type 4 (TRPV4) activation on the function and endothelial-to-mesenchymal transition (EndMT) of human umbilical vein endothelial cells (HUVECs), as well as to explore the effects of TRPV4 activation on blood perfusion and survival of rat perforator flap and the mechanism.Methods The experimental research methods were used. The 3rd to 6th passages of HUVECs were used for experiments and divided into 0.5 μmol/L 4α-phorbol 12, 13-didecanoate (4αPDD) group, 1.0 μmol/L 4αPDD group, 3.0 μmol/L 4αPDD group, 10.0 μmol/L 4αPDD group, and phosphate buffer solution (PBS) group, which were cultivated in corresponding final molarity of 4αPDD and PBS, respectively. The cell proliferation activity at 6 and 12 h of culture was detected using cell counting kit-8 (CCK-8). Another batch of cells was acquired and divided into PBS group, 1 μmol/L 4αPDD group, and 3 μmol/L 4αPDD group, which were treated similarly as described before and then detected for cell proliferation activity at 6, 12, 24, and 48 h of culture. The residual scratch area of cells at post scratch hour (PSH) 12, 24, and 48 was detected by scratch test, and the percentage of the residual scratch area was calculated. The number of migrated cells at 24 and 48 h of culture was detected by Transwell experiment. The tube-formation assay was used to measure the number of tubular structures at 4 and 8 h of culture. The protein expressions of E-cadherin, N-cadherin, Slug, and Snail at 24 h of culture were detected by Western blotting. All the sample numbers in each group at each time point in vitro experiments were 3. A total of 36 male Sprague-Dawley rats aged 8 to 10 weeks were divided into delayed flap group, 4αPDD group, and normal saline group according to the random number table, with 12 rats in each group, and iliolumbar artery perforator flap models on the back were constructed. The flap surgical delay procedure was only performed in the rats in delayed flap group one week before the flap transfer surgery. Neither rats in 4αPDD group nor normal saline group had flap surgical delay; instead, they were intraperitoneally injected with 4αPDD and an equivalent mass of normal saline, respectively, at 10 min before, 24 h after, and 48 h after the surgery. The general state of flap was observed on post surgery day (PSD) 0 (immediately), 1, 4, and 7. The flap survival rates were assessed on PSD 7. The flap blood perfusion was detected by laser speckle contrast imaging technique on PSD 1, 4, and 7. The microvascular density in the flap's choke vessel zone was detected by immunohistochemical staining. All the sample numbers in each group at each time point in vivo experiments were 12. Data were statistically analyzed with analysis of variance for factorial design, analysis of variance for repeated measurement, one-way analysis of variance, least significant difference t test, and Bonferroni correction.Results At 6 and 12 h of culture, there were no statistically significant differences in cell proliferation activity in the overall comparison among PBS group, 0.5 μmol/L 4αPDD group, 1.0 μmol/L 4αPDD group, 3.0 μmol/L 4αPDD group, and 10.0 μmol/L 4αPDD group (P>0.05). At 6, 12, 24, and 48 h of culture, there were no statistically significant differences in cell proliferation activity in the overall comparison among PBS group, 1 μmol/L 4αPDD group, and 3 μmol/L 4αPDD group (P>0.05). At PSH 12, the percentages of the residual scratch area of cells in 1 μmol/L 4αPDD group and 3 μmol/L 4αPDD group were close to that in PBS group (P>0.05). At PSH 24 and 48, compared with those in PBS group, the percentages of the residual scratch area of cells in 3 μmol/L 4αPDD group were significantly decreased (with t values of 2.83 and 2.79, respectively, P<0.05), while the percentages of the residual scratch area of cells in 1 μmol/L 4αPDD group showed no significant differences (P>0.05). At 24 h of culture, the number of migrated cells in 1 μmol/L 4αPDD group and 3 μmol/L 4αPDD group were close to that in PBS group (P>0.05). At 48 h of culture, the number of migrated cells in 1 μmol/L 4αPDD group and 3 μmol/L 4αPDD groups were significantly greater than that in PBS group (with t values of 6.20 and 9.59, respectively, P<0.01). At 4 h of culture, the numbers of tubular structures of cells in 1 μmol/L 4αPDD group and 3 μmol/L 4αPDD group were significantly greater than that in PBS group (with t values of 4.68 and 4.95, respectively, P<0.05 or <0.01). At 8 h of culture, the numbers of tubular structures of cells in 1 μmol/L 4αPDD and 3 μmol/L 4αPDD groups were similar to that in PBS group (P>0.05). At 24 h of culture, compared with those in PBS group, the protein expression level of E-cadherin of cells in 3 μmol/L 4αPDD group was significantly decreased (t=5.13, P<0.01), whereas there was no statistically significant difference in the protein expression level of E-cadherin of cells in 1 μmol/L 4αPDD group (P>0.05); the protein expression level of N-cadherin of cells in 3 μmol/L 4αPDD group was significantly increased (t=4.93, P<0.01), whereas there was no statistically significant difference in the protein expression level of N-cadherin of cells in 1 μmol/L 4αPDD group (P>0.05); the protein expression levels of Slug of cells in 1 μmol/L 4αPDD group and 3 μmol/L 4αPDD group were significantly increased (with t values of 3.85 and 6.52, respectively, P<0.05 or P<0.01); and the protein expression level of Snail of cells in 3 μmol/L 4αPDD group was significantly increased (t=4.08, P<0.05), whereas there was no statistically significant difference in the protein expression level of Snail of cells in 1 μmol/L 4αPDD group (P>0.05). There were no statistically significant differences in the protein expression levels of E-cadherin, N-cadherin, Slug, or Snail of cells between 1 μmol/L 4αPDD group and 3 μmol/L 4αPDD group (P>0.05). The general condition of flaps of rats in the three groups was good on PSD 0. On PSD 1, the flaps of rats in the three groups were basically similar, with bruising and swelling at the distal end. On PSD 4, the swelling of flaps of rats in the three groups subsided, and the distal end turned dark brown and necrosis occurred, with the area of necrosis in flaps of rats in normal saline group being larger than the areas in 4αPDD group and delayed flap group. On PSD 7, the necrotic areas of flaps of rats in the 3 groups were fairly stable, with the area of necrosis at the distal end of flap of rats in delayed flap group being the smallest. On PSD 7, the flap survival rates of rats in 4αPDD group ((80±13)%) and delayed flap group ((87±9)%) were similar (P>0.05), and both were significantly higher than (70±11)% in normal saline group (with t values of 2.24 and 3.65, respectively, P<0.05 or P<0.01). On PSD 1, the overall blood perfusion signals of rats in the 3 groups were basically the same, and the blood perfusion signals in the choke vessel zone were relatively strong, with a certain degree of underperfusion at the distal end. On PSD 4, the boundary between the surviving and necrotic areas of flaps of rats in the 3 groups became evident, and the blood perfusion signals in the choke vessel zone were improved, with the normal saline group's distal hypoperfused area of flap being larger than the areas in delayed flap group and 4αPDD group. On PSD 7, the blood perfusion signals of overall flap of rats had generally stabilized in the 3 groups, with the intensity of blood perfusion signal in the choke vessel zone and overall flap of rats in delayed flap group and 4αPDD group being significantly greater than that in normal saline group. On PSD 7, the microvascular density in the choke vessel zone of flap of rats in 4αPDD group and delayed flap group were similar (P>0.05), and both were significantly higher than that in normal saline group (with t values of 4.11 and 5.38, respectively, P<0.01).Conclusions After activation, TRPV4 may promote the migration and tubular formation of human vascular endothelial cells via the EndMT pathway, leading to the enhanced blood perfusion of perforator flap and microvascular density in the choke vessel zone, and therefore increase the flap survival rate.
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7 激光散斑血流成像仪检测3组行背部髂腰动脉穿支皮瓣原位转移的大鼠术后各时间点的皮瓣血流灌注情况。7A、7B、7C.分别为皮瓣延迟组术后1、4、7 d皮瓣血流灌注情况,随时间延长,皮瓣整体和闭塞血管区域的血流信号增强明显;7D、7E、7F.分别为4α-佛波醇12,13-二癸酸酯组术后1、4、7 d皮瓣血流灌注情况,其中图7E皮瓣存活区与坏死区分界渐清晰,皮瓣远端血流信号弱,闭塞血管区域的血流信号增强;7G、7H、7I.分别为生理盐水组术后1、4、7 d皮瓣血流灌注情况,其中图7I皮瓣远端坏死面积较图7C、7F大,闭塞血管区域和整体存活区域的血流信号强度也较图7C、7F弱
注:白色箭头指示穿支皮瓣血管蒂;紫红色代表血流灌注多,蓝色代表血流灌注少,黑色代表无血流灌注
表1 划痕试验观测的3组人脐静脉内皮细胞划痕后各时间点剩余划痕面积百分比比较(%,
) 组别 样本数 12 h 24 h 48 h PBS组 3 76.5±13.8 56.2±16.0 48.2±16.0 1 μmol/L 4αPDD组 3 68.1±0.5 50.3±9.4 40.8±5.5 3 μmol/L 4αPDD组 3 58.6±0.8 36.4±3.1 28.6±7.4 t1值 1.19 0.85 1.04 P1值 0.733 1.000 0.920 t2值 2.56 2.83 2.79 P2值 0.052 0.028 0.030 注:PBS为磷酸盐缓冲液,4αPDD为4α-佛波醇12,13-二癸酸酯;处理因素主效应,F=8.53,P=0.002;时间因素主效应,F=89.06,P<0.001;两者交互作用,F=0.98,P=0.459;t1值、P1值,t2值、P2值分别为1 μmol/L 4αPDD组、3 μmol/L 4αPDD组与PBS组各时间点比较所得 表2 Transwell实验观测的3组人脐静脉内皮细胞培养各时间点的迁移数量比较(个,
) 组别 样本数 24 h 48 h PBS组 3 95±14 131±8 1 μmol/L 4αPDD组 3 148±12 288±16 3 μmol/L 4αPDD组 3 157±28 374±66 t1值 2.09 6.20 P1值 0.176 <0.001 t2值 2.44 9.59 P2值 0.093 <0.001 注:PBS为磷酸盐缓冲液,4αPDD为4α-佛波醇12,13-二癸酸酯;处理因素主效应,F=37.89,P<0.001;时间因素主效应,F=79.36,P<0.001;两者交互作用,F=12.85,P=0.001;t1值、P1值,t2值、P2值分别为1 μmol/L 4αPDD组、3 μmol/L 4αPDD组与PBS组各时间点比较所得 表3 3组人脐静脉内皮细胞培养各时间点管状结构数量比较(个,
) 组别 样本数 4 h 8 h PBS组 3 53.5±2.1 36.0±9.9 1 μmol/L 4αPDD组 3 79.5±2.1 44.0±1.4 3 μmol/L 4αPDD组 3 81.0±8.5 43.5±2.1 t1值 4.68 1.44 P1值 0.010 0.601 t2值 4.95 1.35 P2值 0.008 0.678 注:PBS为磷酸盐缓冲液,4αPDD为4α-佛波醇12,13-二癸酸酯;处理因素主效应,F=12.84,P=0.007;时间因素主效应,F=88.31,P<0.001;两者交互作用,F=3.93,P=0.081;t1值、P1值,t2值、P2值分别为1 μmol/L 4αPDD组、3 μmol/L 4αPDD组与PBS组各时间点比较所得 -
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