聚乙二醇/聚对苯二甲酸丁二醇酯降解的研究

PEGT/PBT材料研究最早可追溯到1949年Coleman首先提到了用亲水性组分聚环氧乙烷(PEO)改善涤纶树脂染色性的思路[1].1972年,DuPont推出商业化的聚醚酯HytrelTM,主要成分为聚四亚甲基醚二醇(PTMG)/聚对苯二甲酸丁二醇酯(PBT)嵌段共聚物[2].Witsiepe和Hoeslchele等在HytrelTM的基础上,首次合成了PEGT/PBT,但其遇水溶涨、易水解,当时并未引起人们的重视[3].20世纪90年代初,Fakirov等用酯交换法,以聚乙二醇、1,4-丁二醇及对苯二甲酸甲酯为原料,钛酸四丁酯为催化剂,合成了一系列具有不同软、硬段含量的PEGT/PBT多嵌段共聚物[4].     

复温速率对冷冻保存的同种异体血管结构功能的影响

目的比较不同复温速率对冷冻保存的同种异体血管结构和功能的影响。方法取32段新鲜的兔颈总动脉,按照程序降温至-100℃后置于液氮中保存四周。取出后按不同复温速率,分为A组（100℃/min）、B组（30℃/min）、C组（15℃/min）以及未经冷冻的正常组（每组n=8）,通过光镜和电镜观察血管结构变化,采用DNA原位末端标记（TUNEL）比较各组血管壁中细胞的凋亡率。在器官浴槽中测定不同血管的内皮依赖型舒张功能和非内皮依赖型舒张功能。结果光镜和电镜下观察,A组内皮细胞大片脱落,平滑肌细胞变形,胞浆可见大量空泡,而B和C组内皮细胞和平滑肌细胞保存较好。A组血管壁细胞凋亡率高于B、C组（P〈0.05）。血管舒张功能试验结果示,A组最大内皮依赖型舒张力百分比低于B、C组（P〈0.05）,内皮细胞对乙酰胆碱的敏感性也低于B、C组（P〈0.05）。而A组最大非内皮依赖型舒张力百分比低于B、C组（P〈0.05）,但A组平滑肌细胞敏感性较B、C组和正常组没有明显改变。结论逐步缓慢复温对冷冻保存的同种异体血管的结构和功能有一定的保护作用。     

地氟醚预处理与缺氧/复氧损伤内皮细胞凋亡相关基因表达

目的 观察地氟醚预处理对缺氧/复氧(A/R)损伤内皮细胞凋亡相关基因Bcl-2及Bax表达的影响.探讨地氟醚预处理抑制细胞凋亡的机制.方法 选用人脐静脉内皮细胞株(ECV304).将细胞分为五组,即A/R组(A组)、A/R 肿瘤坏死因子α(TNF-α)10 ng/ml组(B组)、地氟醚1.0MAC预处理 A/R组(C组)、地氟醚1.0 MAC预处理 A/R TNF-α 10 ng/ml组(D组)和空白对照组(E组).应用Real-time PCR、Western Blot方法检测各组细胞中Bcl-2及Bax mRNA和蛋白水平.结果 Real-time PCR和Western Blot结果提示,与E组相比,A、B组Bcl-2表达降低,Bax表达升高(P<0.05或P<0.01).经地氟醚预处理后,C、D组细胞较相应未经预处理的A、B组Bcl-2表达增加.Bax表达降低(P<0.05或P<0.01).结论 地氟醚预处理可通过调节Bcl-2及Bax的表达来抑制缺氧/复氧所引起的内皮细胞凋亡.     

不同细胞表面TLR4表达对小鼠重症急性胰腺炎中性粒细胞招募的作用

目的 探索髓系细胞(中性粒细胞、血小板)及内皮细胞表面TLR4表达在重症急性胰腺炎中性粒细胞招募中的作用.方法 采用C3H/He-J和C3H/He-N小鼠通过骨髓移植的方法 制作"髓系细胞TLR4 -/- 和内皮细胞TLR4 +/+ "(A组)及"髓系细胞TLR4 +/+ 和内皮细胞TLR4 -/- "(B组)嵌合体小鼠及"髓系细胞TLR4 +/+ 和内皮细胞TLR4 +/+ "(C组)及"髓系细胞TLR4 -/- 和内皮细胞TLR4 -/- "(D组)纯合体小鼠,腹腔注射蛙皮素、尾静脉注射脂多糖复制SAP模型,检测血浆淀粉酶、PCR测外周血粒细胞TLR4、免疫组化检测胰腺组织内TLR4的表达、胰腺组织萘酚AS-D氯乙酸脂酶染色计数、MPO活性.结果 各实验组小鼠血浆淀粉酶升高;B、C两组外周血粒细胞TLR4mRNA表达高于A、D两组(P<0.05);A、C两组胰腺组织内TLR4阳性,B、D两组阴性;A、C两组AS-D计数高于B、D两组;A、C两组MPO活性亦明显高于B、D两组(P<0.05).结论 内皮细胞而非外周血粒细胞在重症急性胰腺炎中性粒细胞招募聚集中起关键作用.     

大鼠失神经靶肌肉注射异体不同细胞对神经再生影响的研究

目的研究注射异体不同细胞于大鼠失神经靶肌肉对神经再生的影响.方法 SD成年大鼠36只,雌性,体重120～150 g,随机分为4组,每组9只.无菌条件下切断左侧坐骨神经,一期神经外膜缝合.术后即于小腿三头肌处注射相应细胞,7天注射1次,共4次.A组注射单纯雪旺细胞1×106/ml 1 ml,B组注射雪旺细胞加成肌细胞(雪旺细胞∶成肌细胞为1∶1)1×106/ml 1 ml,C组注射肾内皮细胞提取液1 ml,D组注射无血清培养液1 ml作对照.术后3个月取手术侧坐骨神经及坐骨神经所支配的小腿三头肌,进行大体和组织形态学观察、神经鞘细胞密度及单位面积靶肌肉(小腿三头肌)运动终板计数.结果术后3个月,各组近端神经鞘细胞均数为A组0.134 5±0.029 8,B组0.093 1±0.025 6,C组0.072 4±0.023 7,D组0.187 7±0.054 2;A组∶D组P值<0.05,B组∶D组、C组∶D组及A组∶B组P值均<0.01,B组∶C组P值＞0.05.术后3个月各组远端神经鞘细胞密度均数为A组0.186 0±0.042 5,B组0.155 1±0.032 1,C组0.104 7±0.013 3,D组0.240 9±0.056 8;A组∶D组P值<0.05,B组∶D组、C组∶D组及B组∶C组P值<0.01,A组∶B组P值＞0.05.术后3个月各组靶肌肉运动终板个数均数为A组6.000±0.866,B组9.000±2.291,C组12.780±1.394,D组3.110±0.782;A组∶D组、B组∶D组及C组∶D组P值<0.01,A组∶B组、A组∶C组及B组∶C组P值<0.01.结论雪旺细胞、混合细胞、肾内皮细胞提取液均有促进神经再生作用,肾内皮细胞提取液优于雪旺细胞及混合细胞.     

人工血管可降解材料与种子细胞

目的 使用可降解材料聚乳酸和聚羟基乙酸二元共聚物[poly(lactic-co-glycolic acid),PLGA]作为组织工程人工血管支架,探讨种子细胞培养条件,为供临床使用的小口径人工血管研制提供参考.方法 以PLGA作为细胞基质,新生儿脐带血管提取的平滑肌细胞和内皮细胞作种子细胞,体外培养4周后,将平滑肌细胞种植到PLGA上,4周后将内皮细胞种植到平滑肌细胞上,再4周后取出含此细胞的血管片段行细胞性质及活性检测,了解细胞在PLGA上的存活及生长状态.结果 免疫组化检测人工血管中平滑肌肌动蛋白、内皮细胞Ⅷ因子及CD31、CD34均呈阳性表达,证实接种细胞为平滑肌细胞和内皮细胞;放免法检测PLGA细胞培养液,内皮素和6-酮-前列腺素含量明显高于单纯无血清培养液(P＜0.05),证明种植到PLGA内表面的细胞具有活性;光镜和电镜下接种细胞呈典型的平滑肌细胞、内皮细胞形态特征.结论 新生儿脐带血管提取的内皮细胞及平滑肌细胞作为种子细胞,体外培养并种植到PLGA上,短期内仍具有生物活性.     

成骨细胞与血管内皮细胞联合培养的生物学特性

目的探讨成骨细胞与血管内皮细胞联合培养的生物学特性. 方法取2周龄乳兔颅盖骨及肾脏皮质传代培养制备成骨细胞(A组)、血管内皮细胞(B组)及成骨细胞与血管内皮细胞联合培养(C组),用Ⅰ型胶原和血管Ⅷ因子免疫细胞化学染色鉴定成骨细胞和血管内皮细胞,倒置相差显微镜和组织学染色观察细胞的生长特性和细胞相容性,检测碱性磷酸酶 (alkaline phosphatase,ALP)活性,观察血管内皮细胞对成骨细胞产生的ALP活性有无影响,MTT法检测细胞活力,分析细胞生长和增殖情况. 结果免疫细胞化学染色证实,培养的细胞为成骨细胞和血管内皮细胞.倒置相差显微镜、HE和Masson染色均显示两种细胞混合生长良好.ALP检测结果:C组ALP活性明显高于A组和B组(P＜0.01),A组高于B组(P＜0.05).MTT检测结果表明:C组细胞早期增殖较慢,而后期增殖较快. 结论成骨细胞与血管内皮细胞具有良好的相容性,血管内皮细胞能够增强成骨细胞的ALP活性,提高成骨细胞的增殖能力.联合培养细胞具有很强的增殖潜能.     

脱细胞羊膜与脱细胞小肠黏膜下层修复猪创伤性皮肤缺损的比较研究

目的 比较脱细胞羊膜与脱细胞小肠黏膜下层作为创伤性皮肤缺损覆盖物,对创面修复的效果。方法 7只四川长白小猪,每只猪背部两侧各做3个4 cm×4 cm大小的皮肤缺损,深达深筋膜。每侧缺损随机分为3组,用不同敷料覆盖。A组：双层脱细胞羊膜；B组：双层脱细胞小肠黏膜下层；C组：空白,生理盐水纱布覆盖。术后观察创面局部情况、创面愈合率,10 d(2只,各组4个皮肤缺损)、20 d(2只,各组4个皮肤缺损)、30 d(3只,各组6个皮肤缺损)处死动物取材。行组织学观查,炎性细胞、血管内皮细胞及增殖细胞计数,羟脯氨酸含量测定。 结果A、B组覆盖的敷料与创面黏附紧密,与纱布无粘连,更换敷料时创面无渗血。C组纱布与创面黏附紧密,术后22 d前更换纱布时创面出血。组织学观察：术后各时间点A、B组皮下组织内炎性细胞数较C组少；C组皮下组织内胶原分布较A、B组紊乱。术后各时间点A、B组创面愈合较C组高,差异有统计学意义(P<0．05)；C组术后各时间点炎性细胞计数、皮下组织及肉芽组织内增殖细胞数明显高于A、B组,术后20、30 d,羟脯氨酸含量高于A、B组,差异有统计学意义(P<0．05)；3组内皮细胞计数,差异无统计学意义(P>0．05)。A、B组创面局部情况、创面愈合率、病理组织学检查、炎性细胞数计数、血管内皮细胞计数、增殖细胞计数和羟脯氨酸含量,差异均无统计学意义(P>0．05)。 结论 采用脱细胞羊膜、脱细胞小肠黏膜覆盖创伤性皮肤缺损,有提高创面愈合率、减少炎性反应,控制皮下组织及肉芽组织中细胞增殖,使胶原纤维有序排列的作用,能减少创面组织的出血和渗出。脱细胞小肠黏膜覆盖创面具有与脱细胞羊膜覆盖创面相近的修复效果。     

转基因联合泰素帝治疗耐药结直肠癌

目的探讨可溶性血管内皮细胞生长因子受体2基因(sFlk-1)转染联合泰素帝治疗耐药结直肠癌。方法随机均分40只裸鼠至A、B、C、D组,A、B组种植转sFlk-1基因的耐药结直肠癌细胞,C、D组种植耐药结直肠癌细胞,A、C组接受泰素帝(200μg/3d)治疗。70d后比较各组裸鼠瘤重,微血管密度(MVD)和凋亡情况。结果A组瘤重(0．12±0．03)g明显小于B(0．22±0．02)g和C组(1．26±0．03)g、(P＜0．01),但A、B和C组瘤重均小于D组(1．26±0．03)g、(P＜0．01)。A组MVD明显少于其他组,凋亡增加(P＜0．01)。结论sFlk-1基因和泰素帝均能抑制耐药结直肠癌生长,两者联合并非简单作用相加,而是协同增效。     

异体大鼠骨髓单个核细胞胰岛细胞移植治疗糖尿病

目的 观察异体骨髓单个核细胞和胰岛细胞通过肝脏和静脉途径移植后对糖尿病大鼠的治疗作用.方法 密度梯度离心法分离胰岛细胞,淋巴细胞分离液分离骨髓单个核细胞,28只糖尿病大鼠模型随机分为A、B、C、D组,A组在肝脏被膜下多点注射1000个胰岛细胞,B组在体外将1000个胰岛细胞和1×107个骨髓单个核细胞混合后在肝脏被膜下多点注射,C组通过尾静脉注射1000个胰岛细胞,D组在体外将1000个胰岛细胞和1×107个骨髓单个核细胞混合后通过尾静脉注射,移植后于不同时间点尾静脉测定随机血糖,比较不同细胞组合和移植途径之间对糖尿病的治疗作用.结果 A、B组血糖于术后3 d内开始下降,A组血糖可降至正常水平(7.98±2.28)mmol/L,血糖维持正常水平(3.71±0.95)d,B组降至(7.72±1. 75)mmol/L可维持(4.86±1.06)d,静脉移植组血糖于术后4 d内降至正常(7.35±1.40)mmol/L,可维持(7.85±1.46)d,D组静脉注射胰岛于4 d起效(7.00±0.83)mmol/L,血糖可降至正常水平可维持(14.10±1.21)d,各组间血糖随时间变化的趋势及维持正常水平的时间具有统计学意义(P＜0.05).结论 骨髓单个核细胞和胰岛混合细胞通过尾静脉移植对大鼠血糖维持正常时间最长,血糖控制水平最理想.     

Potential differentiation of human mesenchymal stem cell transplanted in rat corpus cavernosum toward endothelial or smooth muscle cells

One of the causes of erectile dysfunction (ED) is the damaged penile cavernous smooth muscle cells (SMCs) and sinus endothelial cells (ECs). To investigate the feasibility of applying immortalized human mesenchymal stem cells (MSCs) to penile cavernous ECs or SMCs repair in the treatment of ED, the in vivo potential differentiation of the immortalized human MSCs toward penile cavernous endothelial or smooth muscle was investigated. One clone of immortalized human bone marrow mesenchymal stem cell line B10 cells via retroviral vector encoding v-myc were transplanted into the cavernosum of the Sprague-Dawley rats and harvested 2 weeks later. The expression of CD31, von Willebrand factor (vWF), smooth muscle cell actin (SMA), calponin and desmin was determined immunohistochemically in rat penile cavernosum. Multipotency of B10 to adipogenic, osteogenic or chondrogenic differentiation was found. Expression of EC specific markers (CD31 or vWF protein) and expression of SMC specific markers (calponin, SMA or desmin protein) were demonstrated in grafted B10 cells. When human MSCs were transplanted into the penile cavernosum, they have the potential to differentiate toward ECs or SMCs. Human MSCs may be a good candidate in the treatment of penile cavernosum injury.     

Heterotypic smooth muscle cell/endothelial cell interactions differ between species

BACKGROUND: In vitro coculture models have been used to study heterotypic cell-cell interactions. This study was performed to determine if species of cell origin affects heterotypic smooth muscle cell (SMC) endothelial cell (EC) interactions in coculture. METHODS: To study the effect of ECs on SMC proliferation, ECs were cultured on porous Dacron membranes. SMCs were added opposite the ECs or on bare membranes on Day 3, and after 4 days, cells were harvested for cell counts. To study the effect of SMCs on EC proliferation, ECs at a density of 5 x 10(5) cells/membrane were added to bare membranes or on membranes opposite SMCs plated 2 days earlier. After 48 h, cells were harvested for cell counts. (N = 3/condition, experiments repeated x2.) Cells of human and bovine aortic origin were used. RESULTS: The effect of coculture on cell growth differed between species. The effect of heterotypic interactions between human cocultured cells was coinhibitory on the rate of growth as compared to the growth of cells cultured alone. Growth of cocultured ECs was 55.2 +/- 8.7% less than that of ECs cultured alone while growth of cocultured SMCs was 27.2 +/- 6.0% less than growth of SMCs cultured alone. This contrasted with the bovine EC stimulation of SMC proliferation, with 66.8 +/- 5.0% greater growth of cocultured SMCs compared to SMCs cultured alone, and failure of bovine SMCs to decrease EC proliferation. CONCLUSIONS: Since significant differences in cell-material interactions occur in vivo between species, the finding that in vitro heterotypic cell-cell interactions are species dependent is not surprising. This fundamental difference in cell behavior stresses the potential importance of using human cells in studies evaluating cell-cell and cell-material interactions in vitro.     

Donor and Recipient Origin of Mesenchymal and Endothelial Cells in Chronic Renal Allograft Remodeling

Chronic transplant dysfunction (CTD) is the leading cause for limited kidney graft survival. Renal CTD is characterized by interstitial and vascular remodeling leading to interstitial fibrosis, tubular atrophy and transplant vasculopathy (TV). The origin of cells and pathogenesis of interstitial and vascular remodeling are still unknown. To study graft-versus-recipient origin of interstitial myofibroblasts, vascular smooth muscle cells (SMCs) and endothelial cells (ECs), we here describe a new rat model for renal CTD using Dark Agouti kidney donors and R26 human placental alkaline phosphatase transgenic Fischer344 recipients. This model showed the development of CTD within 12 weeks after transplantation. In interstitial remodeling, both graft- and recipient-derived cells contributed to a similar extent to the accumulation of myofibroblasts. In arteries with TV, we observed graft origin of neointimal SMCs and ECs, whereas in peritubular and glomerular capillaries, we detected recipient EC chimerism. These data indicate that, within the interstitial and vascular compartments of the transplanted kidney, myofibroblasts, SMCs and ECs involved in chronic remodeling are derived from different sources and suggest distinct pathogenetic mechanisms within the renal compartments.     

Direct comparison of endothelial cell and smooth muscle cell response to supercooling and rewarming

BACKGROUND: Cryoplasty combines mechanical dilatation with the delivery of hypothermia to atherosclerotic plaques. The response of vascular smooth muscle cells (SMCs) and endothelial cells (ECs) to supercooling and subsequent rewarming is still not clear. This study investigated the differential effects of vascular cell survival and proliferation in an in vitro model simulating cryoplasty. METHODS: Bovine aortic ECs and SMCs were cultured separately with medium supplemented with 10% fetal bovine serum. The samples were supercooled to -10 degrees C for 0, 60, or 120 seconds on a cooling stage and then rewarmed in an incubator at 37 degrees C for 0, 6, 12, or 24 hours. Terminal deoxynucleotide transferase-mediated deoxy uridine triphosphate nick-end labeling (TUNEL) and 5'-bromo-2'-deoxyuridine incorporation were used to measure the degree of apoptosis and proliferation respectively. Activation of protein kinase B (AKT), P70 S6 kinase, and P44/42 mitogen-activated protein kinase (MAPK) were assessed by Western blot and quantified using densitometry. Results are given as mean +/- standard error of mean and analyzed by analysis of variance. RESULTS: SMC and EC apoptosis were significantly increased with increasing supercooling and rewarming time, with a higher rate in SMCs. SMC apoptosis was maximal at 60 seconds cooling, followed by 24 hours rewarming (17.05% +/- 0.44%), whereas maximal EC apoptosis was after 120 seconds cooling, followed by 24 hours rewarming (4.21% +/- 0.22%, P < .05). Higher AKT activation was observed in ECs, with a maximum obtained of 3.34-fold at 120 seconds cooling with 24 hours rewarming (P < .05); only modest activation was found in SMCs. ECs had a decreased proliferation with cooling and rewarming time, and although SMCs maintained their low proliferative rate, ECs still had a higher overall proliferation rate that was statistically significant at 60 and 120 seconds cooling without rewarming compared with noncooling and nonrewarming (P < .05). Both p70S6 kinase and p44/42 MAPK activities decreased in SMCs, with significant drop at 60 seconds cooling, followed by 12 hours rewarming (P < .05). However, ECs showed a significant rise of P70 S6 kinase activity at 60 seconds cooling with 12 hours rewarming by 1.62-fold and P44/42 MAPK at 120 seconds cooling with 24 hours rewarming by 1.74-fold (P < .05). CONCLUSION: The higher apoptosis and lower proliferation of SMCs compared with ECs demonstrate the different effects of supercooling and rewarming on different vascular cell types. This information may be important in helping to understand the mechanism by which cryoplasty of atherosclerotic lesions may result in less restenosis.     

The universal NF-kappaB inhibitor a20 protects from transplant vasculopathy by differentially affecting apoptosis in endothelial and smooth muscle cells

Transplant vasculopathy (TV) is an accelerated form of atherosclerosis resulting in chronic rejection of vascularized allografts. The causes of TV are multifactorial and integrate at the level of the vascular wall, leading to a phenotypic switch of endothelial cells (ECs) and smooth muscle cells (SMCs). A20 is a NF-kappaB-dependent stress response gene in ECs and SMCs with potent anti-inflammatory effect in both cell types through blockade of NF-kappaB. A20 expression in ECs and SMCs correlates with the absence of TV in rat kidney allografts and long-term functioning human kidney allografts. We demonstrate that A20 protects ECs from tumor necrosis factor, Fas, and natural killer cell-mediated apoptosis by inhibiting proteolytic cleavage of caspase 8. A20 also safeguards ECs from complement-mediated necrosis. Hence, effectively shutting down cell death pathways initiated by inflammatory and immune offenders associated with TV. In contrast, A20 sensitizes SMCs to cytokine and Fas-mediated apoptosis through a novel nitric oxide (NO)-dependent mechanism. The unexpected proapoptotic effect of A20 in SMCs translates in vivo by the regression of established neointimal carotid lesions following balloon angioplasty in rats. Antedating apoptosis of SMCs, expression of the inducible NO synthase increases in A20-expressing neointimal SMCs, corroborating the involvement of NO in causing the proapoptotic effect of A20 in SMCs. Combined anti-inflammatory and anti- or proapoptotic functions of A20 in ECs and SMCs respectively qualify the positive effect of A20 upon vascular remodeling and healing. We propose that A20-based therapies may be effective in prevention and treatment of TV.     

Endothelial cell activation of the smooth muscle cell phosphoinositide 3-kinase/Akt pathway promotes differentiation

OBJECTIVE: Interactions between endothelial cells (ECs) and smooth muscle cells (SMCs) are fundamental in diverse cardiovascular processes such as arteriogenesis, atherosclerosis, and restenosis. We aimed to determine the intracellular signaling mechanisms by which ECs promote a differentiated SMC phenotype. METHODS: Bovine thoracic aorta ECs and SMCs were isolated and cultured. For co-culture studies, ECs were grown to confluence on one side of a semi-permeable Cyclopore membrane. SMCs were then plated on the opposite side of the membrane and cultured for 24 to 48 hours. For adenovirus experiments, SMCs were infected prior to plating opposite ECs. For conditioned media studies, SMCs cultured alone on plastic were treated with media harvested from EC/SMC in co-culture. SMC phenotype was assayed by microscopy and measurement of two-dimensional area, or by western blotting for contractile protein markers of differentiation. Akt activation was measured by western blotting for phospho-Serine 473. RESULTS: Although SMCs cultured alone exhibit a dedifferentiated synthetic phenotype, we report that bilayer co-culture with ECs induced a differentiated SMC phenotype as measured by morphology and cell area and expression of protein markers of differentiation, including contractile proteins and the cyclin-dependent kinase inhibitor p27 kip . The EC/SMC bilayer co-culture resulted in activation of the SMC protein kinase Akt, with no effect on total Akt expression. Similarly, conditioned media from co-cultured EC/SMC promoted rapid Akt phosphorylation and subsequent expression of differentiation protein markers in SMCs cultured alone. Adenoviral overexpression of constitutively active Akt in SMCs cultured alone mimicked the ability of ECs to induce SMC differentiation. Notably, inhibition of phosphoinositide 3 (PI 3)-kinase activity with wortmannin or adenoviral overexpression of a dominant-negative Akt prevented the EC-mediated effect on SMC morphology and differentiation protein marker expression. CONCLUSIONS: ECs direct SMCs towards a differentiated phenotype through activation of the SMC PI 3-kinase/Akt pathway. CLINICAL RELEVANCE: Interactions between endothelial cells (ECs) and smooth muscle cells (SMCs) are fundamental in diverse cardiovascular processes such as arteriogenesis, collateral blood vessel development, atherosclerosis, and restenosis. Alterations in SMC phenotype occur in each of these processes. Endothelial denudation has been suggested to contribute to the SMC proliferative response to vessel injury by angioplasty or other catheterization procedures. We have employed a co-culture approach to dissect the molecular signals that are dependent on the spatial relationship between ECs and SMCs, and have identified the importance of the PI3K/Akt pathway in EC-induced SMC differentiation. This pathway may suggest targets for therapeutic interventions for intimal hyperplasia and restenosis.     

Mitogenicity and release of vascular endothelial growth factor with and without heparin from fibrin glue

PURPOSE: Fibrin glue (FG) has been used for local cytokine delivery on both vascular grafts and angioplasty sites. We measured the diffusive release of vascular endothelial growth factor (VEGF) and heparin from FG and the mitogenic activity of VEGF with and without heparin in FG on canine endothelial cells (ECs) and smooth muscle cells (SMCs). METHODS: Release of VEGF labeled with iodine 125 and tritiated heparin from FG into the overlying media was serially measured over 96 hours, and the data are reported as the mean percent released +/- SD. Proliferation assays measuring tritiated thymidine incorporation were performed for ECs and SMCs plated in media with 10% serum on FG containing various concentrations of VEGF and heparin. Media was placed on the FG for 24 hours and removed before plating cells to minimize the effect of the released, soluble VEGF and heparin. RESULTS: At 24 hours, 54% +/- 1% and 58% +/- 1% of the radioactive VEGF and heparin were released, respectively, with minimal release thereafter (58% +/- 1% and 66% +/- 1% at 96 hours). The ECs, SMCs, or media only (no cells) was plated on FG containing radioactive VEGF in an immediate or 24-hour delayed fashion for 72 hours to determine the percent release of VEGF into the media with the two different methods of plating. Cell type and the presence or absence of cells did not affect VEGF release, but there was three times more VEGF in the media for the immediate versus delayed plating (P <.001). Without heparin, VEGF at 100 ng/mL or more in the FG was needed to induce EC proliferation. Heparin at 5 U/mL enhanced EC proliferation at the VEGF dose of 100 ng/mL as compared wtih no heparin (P <.001), but not at the VEGF dose of 1000 ng/mL, which likely represents a maximal response. With heparin at 500 U/mL, the ECs died. In contrast, VEGF, in the presence or absence of heparin, did not affect SMC proliferation. CONCLUSIONS: We conclude that FG with VEGF at 1000 ng/mL and heparin at 5 U/mL is the optimal concentration for in vivo use because this may encourage EC, but not SMC, proliferation. The VEGF at 1000 ng/mL should leave mitogenic concentrations of VEGF intact after the initial, diffusive loss, and the addition of heparin at 5 U/mL may enhance VEGF mitogenic activity.     

双层血管细胞种植提高人工血管内皮细胞粘附性

目的　采用血管内皮细胞 (EC)和平滑肌细胞 (SMC)双层种植方法 ,提高人工血管腔面EC的保存率。　方法　聚四氟乙烯 (PTFE)人工血管经纤维连结蛋白预衬处理 ,管腔面先后种植SMC和EC ,将受试的人工血管接入脉冲式体外灌注装置灌注 1h ,计算比较灌注前后受试标本SMC和EC密度。　结果　灌注 1h后 ,单纯EC种植组 61%细胞脱落 ,单纯SMC种植组 3 6%细胞脱落 ,而双层细胞种植组仅有 2 7%EC脱落 ,双层细胞种植组细胞保存率明显高于单纯EC种植组 (P <0 0 1)。低流速预灌注未能改善EC的保存率。　结论　在EC和人工血管壁之间种植SMC可提高EC的保存率     

Endothelial Cell Apoptosis Induces TGF‐β Signaling‐Dependent Host Endothelial–Mesenchymal Transition to Promote Transplant Arteriosclerosis

Endothelial cells (ECs) apoptosis is an initial event in transplant arteriosclerosis (TA), resulting in allograft function loss. To elucidate the precise mechanisms of ECs apoptosis leading to neointimal smooth muscle cells (SMCs) accumulation during TA. We induced apoptosis in cultured ECs by overexpressing p53 through lentivirus‐mediated transfection. ECs apoptosis induced the production of transforming growth factor (TGF)‐β1 in both apoptotic and neighboring viable cells, leading to increased TGF‐β1 in the culture media. Conditioned media from Ltv‐p53‐transfected ECs further promoted transition of cultured ECs to SM‐like cells by activating TGF‐β/Smad3, PI3K/Akt/mTOR, and MAPK/ERK signaling in a TGF‐β‐dependent manner. In transgenic rat aorta transplantation models, inhibition of ECs apoptosis in Bcl‐xL ^+/+ knock‐in rat aortic allografts significantly reduced TGF‐β1 production both in allograft endothelia and in blood plasma, which in turn decreased accumulation of SM22α+ cells from transgenic recipient ECs originally marked with EGFP knock‐in in neointima and alleviated TA. Systemic treatment with SIS3, AP23573, or PD98059 also prevented recipient ECs‐originated SM‐like cells accumulation and intima hyperplasia in aortic allografts. These data suggest that allograft EC apoptosis induced recipient endothelial–mesenchymal (smooth muscle) transition via TGF‐β signaling, resulting in recipient EC‐derived SMC accumulation as a major mechanism of vascular remodeling during TA.