缺氧诱导因子转染内皮祖细胞治疗大鼠缺血后肢

目的 使用缺氧诱导因子-1α(HIF-1α)转染内皮祖细胞(EPC)治疗大鼠后肢缺血,观察EPC、HIF-1α转染EPC对大鼠缺血后肢血管新生和肢体成活的影响.方法 制作SD大鼠后肢缺血模型,将动物随机分为3组,每组6只.将构建的HIF-1α基因真核表达载体转染入EPCs后通过尾静脉注射入大鼠体内,并与注射磷酸盐缓冲液(PBS)或EPC的大鼠进行比较,观察转染HIF-1α对新生血管形成的影响.结果 (1)EPC组、HIF组较PBS组肢体恢复率明显增加(P<0.05),EPC组肢体恢复率较HIF组差(P<0.05).(2)与PBS组比较,各时间点中EPC、HIF组微血管密度(MVD)均明显增多(P<0.05),HIF组较EPC组明显增高(P<0.05).(3)HIF组的HIF与血管内皮生长因子(VEGF)蛋白表达较PBS组、EPC组明显增多(P<0.05).PBS组Capase-3的表达较EPC组、HIF组明显增多(P<0.05).(4)术后7 d,各组的大鼠肢体灌注均明显降低,但EPC、HIF组细胞的血流灌注较PBS组多(P<0.01).术后14、21 d,与PBS对照组比较,HIF组的血流灌注恢复明显(P<0.01),EPC组血流灌注较HIF组少(P<0.05).结论 EPCs对大鼠缺血后肢的局部血管新生有明显促进作用,联合应用HIF-1α和EPCs有更优的治疗效果.     

Autologous bone marrow implantation induced angiogenesis and improved deteriorated exercise capacity in a rat ischemic hindlimb model

BACKGROUND: Bone marrow possesses endothelial progenitor cells that secrete several growth factors and can contribute to the formation of new capillaries. In the present study, we investigated the extent of angiogenesis induced by implantation of autologous bone marrow cells (BMCs) in a rat ischemic hindlimb model and studied whether the increased collateral vessels can improve deteriorated physical function. MATERIALS AND METHODS: Ischemic hindlimb was created by ligation of the femoral artery and its branches in Dark Agouti (DA) rats. BMCs (1 x 10(7)) were injected percutaneously at six points into the gastrocnemius muscle. To assess angiogenesis, histologic evaluation and microangiography were performed at 2 weeks postligation. Severity of the ischemic insult was evaluated by measuring blood flow in the adductor and gastrocnemius muscles using nonradioactive colored microspheres and by determining the femoral arteriovenous oxygen difference (AVDO(2)) at 2 weeks postligation. Running time on a motor-driven treadmill was used to represent exercise capacity. RESULTS: The histologic evaluation and microangiogram showed that the implanted BMCs induce angiogenesis. Blood flow to the adductor muscle on the treated side in the bone marrow cell implantation (BMI) group was significantly restored to 77.3 +/- 19.3% of that of the normally perfused limb in comparison to that in control groups (P < 0.05). AVDO(2) in the BMI group significantly decreased when compared with AVDO(2) in control groups. Rats in the BMI group ran approximately 1.5 times longer than rats in control groups at 2 and 4 weeks postligation (P < 0.01). CONCLUSIONS: Implantation of autologous BMCs induced angiogenesis and improved deteriorated exercise capacity in our rat ischemic hindlimb model.     

Enhanced angiogenesis and growth of collaterals by in vivo administration of recombinant basic fibroblast growth factor in a rabbit model of acute lower limb ischemia: dose-response effect of basic fibroblast growth factor.

The purpose of this study was to evaluate the effects of exogenous recombinant basic fibroblast growth factor (bFGF) on angiogenesis in severely ischemic tissue beds. We used a two-stage procedure to produce severe ischemia of the hindlimb of 34 New Zealand rabbits. The ischemic hindlimb received intramuscular injection of saline (group A), 1 microgram bFGF (group B), or 3 micrograms bFGF (group C), daily for 2 weeks. Tissue perfusion, skeletal muscle infarction, angiogenesis, and collateral growth were assessed by angiography, transcutaneous oximetry (TcPO2), quantitative spectrophotometric assay of triphenyltetrazolium chloride reduction in muscle, capillary density (capillaries per square millimeter), and capillary per muscle fiber ratio. There were no significant differences in baseline TcPO2 among the three groups for both thigh and calf measurements. Angiography revealed extensive perfusion of the left hindlimb in all the assessed bFGF treated animals. Both thigh and calf TcPO2 values showed a significant increase in all groups over the 14 days ischemia was induced (p less than 0.0001), but the two treatment groups exhibited a much more rapid rise in TcPO2 than the control group (p less than 0.0001). The capillaries per square millimeter and capillaries per muscle fiber ratios were significantly increased in all posttreatment measurements for all animals that received bFGF. The treatment groups with bFGF had a significant (p = 0.025) increase in thigh muscle viability compared with controls based on triphenyltetrazolium chloride reduction. Whereas there was evidence of muscle infarction in both the thighs of groups A and B, there was none in group C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intra-arterial bone marrow cell transplantation induces angiogenesis in rat hindlimb ischemia

BACKGROUND: Bone marrow (BM) cells have been shown to augment local angiogenesis by differentiating vessels themselves and/or secreting paracrinally angiogenic growth factors. Herein, the angiogenic effects of intra-arterial BM mononuclear cell (BM-MNC) transplantation were evaluated in a rat ischemic hindlimb model. METHODS: Unilateral hindlimb ischemia was created by excising the femoral artery and its branch in Lewis rats. BM-MNCs were isolated by centrifugation through a Histopaque density gradient. One week after excision of the unilateral femoral artery, BM-MNCs (5 x 10(6) cells, Group A, n = 6) or PBS (Group B, n = 7) were injected into the ischemic thigh skeletal muscles at the six points with a gauge needle. Another injection of BM-MNCs (3 x 10(7) cells, Group C, n = 6) or PBS (Group D, n = 7) was administered via the indwelling catheter in the right common iliac artery. RESULTS: Four weeks after the BM-MNC transplantation, angiographic examination revealed the development of collateral vessels in both BM-MNC-transplanted groups. The difference in skin temperature between right and left hindlimbs was significantly reduced in both BM-MNC-transplanted groups (0.93 +/- 0.15 vs. 2.84 +/- 0.35 vs. 1.20 +/- 0.26 vs. 2.61 +/- 0.37 degrees C, Group A vs. Group B vs. Group C vs. Group D, p < 0.05). Moreover, immunohistochemical analysis demonstrated that capillary endothelial cells were increased in both BM-MNC-transplanted groups. CONCLUSION: BM-MNC implantation was able to induce functional neovascularization in rat ischemic hindlimb. The intra-arterial administration offered similar levels of angiogenic activity as intramuscular injection.     

Therapeutic angiogenesis induced by local autologous bone marrow cell implantation

BACKGROUND: Therapeutic angiogenesis was induced by local autologous bone marrow cell implantation (BMCI) in ischemic hindlimb or ischemic heart models in rats. This study was designed to investigate the toxicity and therapeutic potency of local BMCI using a chronic coronary occlusion model in dogs. METHODS: The canine chronic coronary occlusion model was created by ligating of the left anterior descending artery (LAD). The myocardium in the left ventricle was divided into distinct normal, marginal, and infarction areas 30 days after LAD ligation. Each area was injected at two locations, with either 2 x 10(7) bone marrow cells (n = 7, BMCI group) or 0.1 mL phosphate-buffered saline (PBS) only (n = 7, PBS group), respectively. Hemodynamics were evaluated by a single ultrasonic transducer and echocardiography before and 30 days after the treatment. Angiogenesis was evaluated by vessel count 30 days after the treatment. The toxicity of BMCI treatment was also evaluated in 8 normal dogs by following changes in electrocardiography (ECG), echocardiography, local histology, and systemic biochemistry indexes. RESULTS: There was a significantly higher percentage of wall thickening in the marginal area in the BMCI group than in the PBS group 30 days after treatment (14.5 +/- 2.28 versus 8.1 +/- 3.00, p = 0.002). Significantly more microvessels were observed in the marginal area in the BMCI group than in the PBS group 30 days after treatment (127.7 +/- 20.1 versus 88.0 +/- 10.2/field, p = 0.0007). No systemic or local toxicity was found following BMCI treatment in the acute or chronic phases. CONCLUSIONS: BMCI treatment improved local wall thickening dynamics, presumably due to the angiogenesis induced by the treatment. This indicates that it might be a safe and effective therapy for ischemic heart disease.     

Administration of bone marrow cells into surgically induced fibrocollagenous tunnels induces angiogenesis in ischemic rat hindlimb model

We established a comparative model of angiogenic induction in previously formed fibrocollagenous tunnels in rat inner thigh muscles. A unilateral hindlimb chronic ischemia model was performed in male Sprague-Dawley rats. A device was then inserted in the central portion of the inner thigh muscles. Vascularity in the ischemic limb was determined by means of an angiographic score, capillary/fiber ratio, and endothelial proliferation by histochemistry and immunohistochemistry. Autologous transplant of bone marrow, vascular endothelial growth factor (VEGF), or collagen-polyvinylpyrrolidone plus heparin induced significant vascularization of the ischemic hindlimb when compared to saline solution. However, the bone marrow group presented a higher angiographic score than the other two. No differences among groups were observed in capillary/fiber ratio or proliferation, except for the VEGF group, where capillary proliferating cells were significantly higher than in controls. Based on these results, bone marrow-derived progenitor cells may constitute a safe and viable alternative for the induction of therapeutic angiogenesis.     

Systems for therapeutic angiogenesis in tissue engineering

The goals in tissue engineering include the replacement of damaged, injured, or missing body tissues with biologically compatible substitutes. To overcome initial tissue-mass loss, improved vascularization of the regenerated tissue is essential. Two pathways of tissue neovascularization are known: vasculogenesis, the in situ assembly of capillaries from undifferentiated endothelial cells (EC), and angiogenesis, the sprouting of capillaries from preexisting blood vessels. Recent advances in our understanding of the process of blood-vessel growth have provided significant tools for the neovascularization of bioengineered tissues. Several growth factors serve as stimuli for EC proliferation and migration as well as the formation of new blood vessels. They convey their effects via specific receptors expressed on the surface of EC. Vascular epithelial growth factor (VEGF) is a major regulator of neovascularization. VEGF plays a major role in the early development of blood-cell progenitors. Basic fibroblast growth factor (bFGF) was identified as the first angiogenic factor. It is a potent inducer of EC proliferation and blood-vessel growth in vitro and in vivo. VEGF and bFGF have been injected into undervascularized ischemic tissues, resulting in new blood-vessel formation and tissue perfusion. Gene-therapy approaches using VEGF cDNA injection into ischemic tissues have augmented the formation of collateral vessels. Angiogenic factors such as VEGF and bFGF have also been incorporated into bioengineered tissues and have facilitated blood-vessel growth. Other approaches such as prevascularization of the matrix prior to cell seeding and incorporation of EC into the bioengineered tissues have produced encouraging results. This article reviews the process of blood-vessel growth and tissue vascularization, placing emphasis on strategies that can be employed for efficient vascularization of engineered tissues in vitro and in vivo.     

新型纳米微球载碱性成纤维细胞生长因子促进新生血管形成的研究

目的 制备载碱性成纤维细胞生长因子(bFGF)甲基丙烯酸缩水甘油酯修饰葡聚糖纳米凝胶微球,观察其对新生血管生成的诱导和促进作用.方法 采用改良乳液聚合法制备载bFGF纳米微球(bFGF-Dex-GMA-NPs),对纳米微球的外形、包封率、体外释药特征进行常规检测,建立兔后肢缺血模型后,分为以下几组(每组6只):安慰剂治疗组(注射磷酸盐缓冲液)(A组);bFGF治疗组(B组);载bFGF纳米微球组(C组),分别于治疗后7、21 d用99mTc标记的sestamibi对后肢血流进行分析,并于21 d将动物处死,取局部肌肉组织切片进行免疫组织化学染色,镜下对毛细血管计数.结果 合成的纳米微球外形圆整,无相互粘连,包封率高达80.9%,并能较好地控制bFGF的释放,持续释放时间超过25 d.后肢缺血模型治疗第7天,B组和C组能量计数分别为(130.95±14.59)、(127.60±11.36),明显高于A组(27.65±6.82)(P＜0.05),但B组和C组间差异无统计学意义(P＞0.05),第21天,C组能量计数增加到(450.69±21.06),明显高于A组(39.89±8.45)和B组(165.34±15.88)(P＜0.05).免疫组织化学染色结果显示C组毛细血管密度是(99.00±5.44)/mm2,明显高于其他两组2.00±0.59(A组)、13.00±1.35(B组)(P＜0.05).结论 载bFGF纳米微球可以控制bFGF长时间释放,对缺血组织新生血管形成有优于单纯bFGF的诱导和促进作用.     

rhG-HGF联合成纤维细胞生长因子促进下肢血管新生的实验研究

目的 探讨重组人肝细胞生长因子(rhG-HGF)联合成纤维细胞生长因子(bFGF)对下肢缺血动物模型血管新生的影响.方法 制作80只小鼠左下肢缺血模型,术后随机分为4组,每组20只:(1)生理盐水对照组;(2)bFGF组;(3)rhG-HGF组;(4)rhG-HGF+bFGF组.应用多谱勒超声血流测定、肌肉毛细血管密度测定,比较4组缺血肢体血流/正常肢体血流比值及肌肉毛细血管密度.结果 术后4周,4组缺血肢体血流/正常肢体血流比值及肌肉毛细血管密度为:rhG-HGF+bFGF组>rhG-HGF组>bFGF组>生理盐水组(均P<0.05).结论 rhGvHGF促进血管新生作用强于bFGF,两者联合应用有协同作用,可以更明显改善下肢缺血状况.     

脐带间充质干细胞分化为内皮细胞促进血管新生

目的 探讨脐带间充质干细胞能否在体内外分化为内皮细胞,参与血管新生.方法 体外实验采用内皮细胞生长因子和碱性成纤维细胞生长因子对脐带间充质于细胞进行诱导,观察其形态变化.体内实验将脐带间充质干细胞移植到小鼠后肢缺血模型中,采用免疫组织化学鉴定细胞在体内的迁移和分化,激光多普勒血流成像仪鉴定缺血局部血流恢复情况.结果 在体外脐带间充质干细胞能够形成血管网样结构.在体内脐带间充质干细胞能够分化为内皮细胞,表达CD31抗体,参与实验组的动物血管重建.与小鼠的血管网络发生整合,实验组的动物后肢血流灌注明显好于对照组.结论 脐带间充质干细胞能够分化为内皮细胞,参与血管新生,为治疗性血管新生提供新的细胞选择.     

Bimodal concentration-dependent effect of thrombin on endothelial cell proliferation and growth factor release in culture

BACKGROUND: The role of thrombin in the stimulation of endothelial cell (EC) proliferation is controversial. The aim of this study was to investigate if thrombin regulates cell proliferation and production of platelet-derived growth factor (PDGF), bovine fibroblast growth factor (bFGF), and transforming growth factor beta(1) (TGF-beta(1)) by bovine aortic ECs. METHODS: ECs, obtained from thoracic aortas of calves, were stimulated with thrombin at various concentrations (from 0.05 to 1.0 IU/ml) in serum free culture. Mitogenic activity of thrombin on ECs was determined by tritiated thymidine uptake. The release of PDGF, bFGF, and TGF-beta(1) was assessed by ELISA. PDGF release was confirmed by Western blot and bFGF and TGF-beta(1) mRNA expression was determined by polymerase chain reaction (PCR). RESULTS: Thrombin at high concentrations did not cause any increase in EC proliferation after 72 h of culture and induced inhibition of EC proliferation after 96 h and 8 days of culture. It induced a decrease in PDGF release and an increase in TGF-beta(1) release. Thrombin at low concentrations induced a significant increase in EC proliferation at 72 h, 96 h, and 8 days of culture. It induced an increase in PDGF release and a decrease in TGF-beta(1) release. bFGF release was higher than control at all thrombin concentrations. These data were confirmed by Western blot and PCR studies. CONCLUSIONS: Thrombin regulates EC growth through the inhibition of EC proliferation at high concentrations and through the stimulation of EC proliferation at low physiological concentrations. EC proliferation is partially mediated by autocrine production of PDGF, bFGF, and TGF-beta(1).     

The induction of angiogenesis by the implantation of autologous bone marrow cells: a novel and simple therapeutic method.

BACKGROUND: Bone marrow contains many kinds of primitive cells that could differentiate to endothelial cells and secrete several growth factors. In the current study, we attempted to induce therapeutic angiogenesis by implanting autologous bone marrow cells (BMCs) and using a rat ischemic hind limb model. METHODS: BMCs were prepared by removing red blood cells. A rat ischemic hind limb model was made by the ligation of the left femoral artery and its branches. BMCs were injected into 7 points of the ischemic muscles. To assess angiogenesis, a microangiogram, laser Doppler, and histologic evaluation were performed after the surgical procedure. RESULTS: A microangiogram and histologic evaluation showed that angiogenesis was significantly induced in the ischemic hind limb by the implantation of BMCs. Laser Doppler imaging analysis showed that blood flow was significantly increased after implantation of BMCs. Some implanted BMCs were stained positively with CD31 and vascular endothelial-cadherin (VE-cadherin), which might have been incorporated into the vasculature. The condition of ischemia caused an elevation in the level of basic fibroblast growth factor in the ischemic muscle and also in interleukin-1beta derived from the implanted BMCs, which might contribute to angiogenesis. CONCLUSION: These findings indicate that autologous bone marrow implantation may be a novel and simple method for inducing therapeutic angiogenesis.     

碱性成纤维细胞生长因子促血管内皮细胞增生的研究

目的 探讨碱性成纤维细胞生长因子(bFGF)对人血管内皮细胞(EC)增生的影响及其机制，明确bFGF对烟曲霉素衍生物(TNP-470)及地塞米松(Dex)作用的影响。方法 培养人脐静脉内皮细胞(HUVEC)，采用MTT法测定EC生长活性，免疫组织化学方法检测EC中核因子(NF—KB)和ki-67的表达。结果 bFGF有显著促进EC增生的作用，可使核内NF-κB和ki-67表达增强ITNP-470及Dex可抑制EC增生，使核内NF—κB和ki-67表达减少；bFGF逆转二者的抑制效应。结论 bFGF能促进EC增生，其机制可能是通过激活NF—κB，使细胞由静止期进入增殖期，促进DNA合成，细胞分裂增殖。TNP-470及Dex可抑制NF—κB活化，bFGF可逆转二者的抑制效应。     

Vascular endothelial growth factor increases the migration and proliferation of smooth muscle cells through the mediation of growth factors released by endothelial cells

BACKGROUND: Vascular endothelial growth factor (VEGF), a highly specific chemotactic and mitogenic factor for vascular endothelial cells (EC), appears to be involved in the development of atherosclerosis. The purpose of our study was to assess if VEGF might indirectly stimulate SMC migration and proliferation in a EC-SMC coculture system, through the mediation of growth factors released by EC. METHODS: Bovine aortic SMC were cocultured with bovine aortic EC treated with hrVEGF, to assess SMC proliferation and migration. The release and mRNA expression of basic fibroblast growth factor (bFGF) and transforming growth factor beta(1) (TGFbeta(1)) were assessed by ELISA and PCR analysis. RESULTS: hrVEGF (10 ng/ml), added to EC cocultured with SMC, induced a significant increase in tritiated thymidine uptake by SMC as compared to controls (P < 0.01) and a significant increase in SMC migration in respect to control (27%; P < 0.01). EC stimulated with hrVEGF increased the release and the expression of bFGF and decreased the release and the expression of TGFbeta(1) with a statistically significant difference in respect to controls (P < 0.001). CONCLUSIONS: VEGF indirectly stimulates SMC proliferation and migration through the modulation of bFGF and TGFbeta(1) released by EC.     

碱性成纤维细胞生长因子促进兔缺血后肢血管新生的实验研究

目的:了解局部应用碱性成纤维细胞生长因子(bFGF)对促进兔缺血后肢血管新生的作用。方法:25只日本大耳白兔随机分2组,外科结扎切断各兔股动脉及其分支,制作兔后肢缺血模型。试验组各兔在缺血后肢肌肉内多次注射重组人bFGF蛋白(n=15);对照组给予等剂量生理盐水(n=10)。术后4周,各兔行腹主动脉造影观察侧支血管形成情况,取内收肌和腓肠肌肌肉行病理切片HE染色应用图像分析系统统计血管密度,并用免疫组织化学方法检测内收肌和腓肠肌中VEGF阳性表达的血管数。结果:试验组兔侧支循环血管条数、血管密度及VEGF阳性表达的血管数均大于对照组(P<0.01),缺血状态得到改善。结论:在兔缺血后肢肌肉中注射bFGF蛋白可促进血管新生,增加兔缺血后肢血液灌注,改善肢体缺血状态。     

血管内皮生长因子转染内皮祖细胞治疗大鼠缺血后肢的研究

目的 使用血管内皮生长因子(VEGF)转染内皮祖细胞(EPC)治疗大鼠缺血后肢,观察EPC、VEGF转染EPC对大鼠缺血后肢的新生血管和肢体成活的影响.方法 制作SD大鼠后肢缺血模型,将动物随机分为3组,每组6只.将构建的VEGF基因真核表达载体转染入骨髓来源的EPCs后通过尾静脉注射人大鼠体内,并与使用磷酸盐缓冲液(PBS)或EPC的动物进行比较,观察转染VEGF的EPCs在缺血部位的聚集和形成新生血管的情况.结果 (1)动物总残肢率比较,CELL组、VEGF组较PBS组明显增加的肢体恢复率(P<0.05),CELL组肢体恢复率较VEGF组差(P<0.05).(2)毛细血管密度与PBS组比较,各时间点中CELL、VEGF组MVD均明显增多(P<0.05).(3)缺血肢体VEGFa的表达:VEGF组的VEGF蛋白表达较PBS组、CELL组、明显增多(P<0.05);(4)手术后7、14、28 d,与PBS对照组比较,CELL、VEGF组细胞的血流灌注有较大程度的恢复(P<0.01).结论 VEGFa基因转染EPCs对缺血部位的血管新生有重要影响,联合应用VEGFa基因和EPCs治疗缺血后肢有较好的协同作用.     

Angiogenesis induced by the implantation of self-bone marrow cells: a new material for therapeutic angiogenesis

Bone marrow, contains various primitive cells that are thought to secrete several angiogenic growth factors and may also differentiate into endothelial cells. The present study was conducted to investigate the possibility that bone marrow cells could be a novel material to induce angiogenesis. The expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in rat bone marrow cells was examined by immunohistochemistry. The production of VEGF was compared in tissue culture supernatant under the conditions of normoxia and hypoxia. The process of angiogenesis that occurred following the implantation of bone marrow cells was determined using a rat cornea model. VEGF- and bFGF-positive cells were found in rat bone marrow. The production of VEGF from bone marrow cells was significantly more enhanced by hypoxic conditions than by normoxic conditions. The rat cornea model showed that bone marrow cell implantation created new vessels. The implantation of self-bone marrow cells is a novel and simple method of inducing angiogenesis.     

Toward surgical angiogenesis using slow-released basic fibroblast growth factor.

OBJECTIVE: Therapeutic angiogenesis using basic fibroblast growth factor (bFGF) in coronary artery disease has been documented in a number of papers. However, the effectiveness is discrepant among documents. In this study, we evaluated the distribution of bFGF in the rat heart by different administration methods, and investigated the efficacy of slow-released administration of bFGF using biodegradable hydrogel microspheres (bFGF microspheres) in a pig infarction model toward an enhanced coronary bypass surgery. METHODS: Heart failure due to myocardial infarction was induced in rats and pigs. In the rat study, free form of bFGF (central venous injection, intracoronary injection, and intramyocardial administration) and bFGF microspheres (intramyocardial administration) were given 4 weeks later. The remaining radioactivity of bFGF in the hearts was estimated 1, 24, and 72 h later. On the other hand, the pigs were randomized into two groups 4 weeks after myocardial infarction. While the control group (n=8) had gelatin hydrogel microspheres with saline, the FGF group (n=8) received bFGF microspheres in the left ventricular (LV) wall. RESULTS: In the rat study, after intramyocardial administration of bFGF microspheres, more bFGF remained in the rat heart 72 h later compared with the other methods (P<0.0001). In the pig study, 4 weeks after the treatment, the FGF group had smaller LV diastolic diameter (48.7+/-5.3 vs. 56.7+/-5.2 mm, P<0.01) than the control group. LV end-systolic elastance was higher in the FGF group (2.96+/-1.2 vs. 1.06+/-0.3 mmHg/ml, P<0.01). In microscopic examinations, many neovessels were found in and around the scar tissue, and the vascular density in the FGF group was significantly higher (61.5+/-18.3 vs. 153.0+/-29.0/mm2, P<0.01). In addition, the infarcted LV walls were less expanded and more thickened in the FGF group. CONCLUSIONS: Biodegradable hydrogel microspheres with bFGF improved LV function and inhibited LV remodeling by angiogenesis in pigs with chronic myocardial infarction. bFGF microspheres into ischemic myocardium may revascularize small ungraftable vessels and may potentially increase distal run-off when applied in coronary bypass surgery.     

Controlled delivery of bFGF to recipient bed enhances the vascularization and viability of an ischemic skin flap

Therapeutic angiogenesis is a promising approach to treat ischemic skin flaps. We delivered basic fibroblast growth factor (bFGF) to the recipient bed of a rat dorsal skin flap by a drug delivery system with acidic gelatin hydrogel microspheres (AGHMs), and assessed augmentation of neovascularization and flap viability. An axial skin flap was elevated on the back of male Sprague–Dawley rats, and bFGF solution or bFGF-impregnated AGHMs were injected into the recipient bed. The dose of bFGF in the bFGF solution was set to 15 (Sol-15 group), 50 (Sol-50 group), or 150 μg (Sol-150 group). Correspondingly, 2 mg AGHMs were impregnated with 15 (AGHM-15 group), 50 (AGHM-50 group), or 150 μg (AGHM-150 group) bFGF. Other groups of animals received phosphate-buffered saline (Sol-Cont group) or phosphate-buffered saline-impregnated AGHMs (AGHM-Cont group) as controls. Seven days later, analyses of the area of necrosis, microangiographic findings, and histological findings in the flap were carried out. The area of necrosis in the AGHM-150 group was significantly smaller than that in the other groups. Microangiographic and histological analyses showed that neovascularization of the ischemic skin flap significantly increased in the AGHM-150 group as compared with the Sol-150 group and the AGHM-Cont group. These findings suggest that continuous delivery of bFGF to the recipient bed by bFGF-impregnated AGHMs enhances the viability of an ischemic skin flap.