Augmentation of postnatal neovascularization with autologous bone marrow transplantation

Stromal cell-derived factor-1 enhances pro-angiogenic effect of granulocyte-colony stimulating factor

OBJECTIVE

Granulocyte colony-stimulating factor (G-CSF) mobilizes bone marrow mononuclear cells into the peripheral circulation. Stromal cell-derived factor-1 (SDF-1) enhances the homing of progenitor cells mobilized from the bone marrow and augments neovascularization in ischemic tissue. We hypothesize that SDF-1 will boost the pro-angiogenic effect of G-CSF.

METHODS AND RESULTS

NIH 3T3 cells retrovirally transduced with SDF-1alpha gene (NIH 3T3/SDF-1) were used to deliver SDF-1 in vitro and in vivo. Endothelial progenitor cells (EPCs) co-cultured with NIH 3T3/SDF-1 cells using cell culture inserts migrated faster and were less apoptotic compared to those not exposed to SDF-1. NIH 3T3/SDF-1 (10(6) cells) were injected into the ischemic muscles immediately after resection of the left femoral artery and vein of C57BL/6J mice. G-CSF (25 mug/kg/day) was injected intraperitioneally daily for 3 days after surgery. Blood perfusion was examined using a laser Doppler perfusion imaging system. The perfusion ratio of ischemic/non-ischemic limb increased to 0.57+/-0.03 and 0.50+/-0.06 with the treatment of either SDF-1 or G-CSF only, respectively, 3 weeks after surgery, which was significantly higher than the saline-injected control group (0.41+/-0.01, P<0.05). Combined treatment with both SDF-1 and G-CSF resulted in an even better perfusion ratio of 0.69+/-0.08 (P<0.05 versus the single treatment groups). Mice were sacrificed 21 days after surgery. Immunostaining and Western blot assay of the tissue lysates showed that the injected NIH 3T3/SDF-1 survived and expressed SDF-1. CD34(+) cells were detected with immunostaining, capillary density was assessed with alkaline phosphatase staining, and the apoptosis of muscle cells was viewed using an in situ cell death detection kit. More CD34(+) cells, increased capillary density, and less apoptotic muscle cells were found in both G-CSF and SDF-1 treated group (P<0.05 versus other groups).

CONCLUSION

Combination of G-CSF-mediated progenitor cell mobilization and SDF-1-mediated homing of EPCs promotes neovascularization in the ischemic limb and increases the recovery of blood perfusion.

Enhancement of Viability of Fat Grafts in Nude Mice by Endothelial Progenitor Cells

BACKGROUND

A recent discovery showed that endothelial progenitor cells (EPCs) could augment collateral vessel growth to ischemic tissues.

OBJECTIVE

The objective was to demonstrate the effects of EPCs on the vasculogenesis and survival of free transplanted fat tissues in nude mice.

METHODS

EPCs from human donors were cultured in vitro for 7 days. Human fat tissues were injected subcutaneously into the scalps of 20 6-week-old nude male mice. EPCs stained with CM-DiI were mixed with the transplanted fat tissues and injected into the mice. EBM-2 medium was used as control group. The animals were euthanized 15 weeks after the procedure. Graft volume were measured, and histologic evaluation was performed. The central part of fat tissues was histologically evaluated 15 weeks after the fat injection.

RESULTS

The survival volume of the experimental group was significantly greater than that of the control group (p< .05). Less cyst formation and fibrosis was obtained in the experimental group. Histologic evaluation of the central part of fat tissues 15 weeks after the fat injection showed that capillary densities increased markedly in the experimental group mice.

CONCLUSION

The results indicate that EPCs have the ability to enhance the survival and the quality of the transplanted fat tissues.

Autologous bone marrow mononuclear cell implantation induces angiogenesis and bone regeneration in a patient with compartment syndrome

A 28-year-old man developed compartment syndrome in the right lower leg after fracture of the tibia and fibula. Despite fasciotomy, many arteries collapsed and union of the tibial and fibula fractures did not occur. Autologous bone marrow mononuclear cell (BMMNC) implantation for therapeutic angiogenesis and subsequent bone regeneration was performed and 4 weeks later, angiography showed a marked increase in collateral vessels surrounding the tibial fracture, and union was completed 6 months later. BMMNC implantation therapy might provide therapeutic angiogenesis and osteogensis in patients with compartment syndrome.

Effects of adrenomedullin on acute ischaemia-induced collateral development and mobilization of bone-marrow-derived cells

Adrenomedullin exerts not only vasodilatory effects, but also angiogenic effects. In the present study, we investigated the effects of adrenomedullin on collateral formation and circulating bone-marrow-derived cells after acute tissue ischaemia. Bone marrow of 8–10-week-old female C57BL/6J mice was replaced with that from GFP (green fluorescent protein) transgenic mice (GFP mice). At 8 weeks after transplantation, hindlimb ischaemia was induced by resecting the right femoral artery and a plasmid expressing human adrenomedullin (50 μg) was injected into the ischaemic muscle, followed by in vivo electroporation on a weekly basis. Overexpression of adrenomedullin significantly enhanced the blood flow recovery compared with controls (blood flow ratio, 1.0±0.2 compared with 0.6±0.3 respectively, at week 4; P<0.05) and increased capillary density in the ischaemic leg as determined by anti-CD31 immunostaining of the ischaemic muscle (567±40 compared with 338±65 capillaries/mm2 respectively, at week 5; P<0.05). There were more GFP-positive cells in the thigh muscle of the mice injected with adrenomedullin than in that of the control mice (29.6±4.5 compared with 16.5±3.3 capillaries/mm2 respectively, at week 5; P<0.05). We repeated the same experiments using LacZ-knock-in mice instead of GFP mice, and obtained similar results. These findings suggest that adrenomedullin may augment ischaemia-induced collateral formation with some effects on circulating bone-marrow-derived cells.

Indium-111 oxine labelling affects the cellular integrity of haematopoietic progenitor cells

PURPOSE

Cell-based therapy by transplantation of progenitor cells has emerged as a promising development for organ repair, but non-invasive imaging approaches are required to monitor the fate of transplanted cells. Radioactive labelling with (111)In-oxine has been used in preclinical trials. This study aimed to validate (111)In-oxine labelling and subsequent in vivo and ex vivo detection of haematopoietic progenitor cells.

METHODS

Murine haematopoietic progenitor cells (10(6), FDCPmix) were labelled with 0.1 MBq (low dose) or 1.0 MBq (high dose) (111)In-oxine and compared with unlabelled controls. Cellular retention of (111)In, viability and proliferation were determined up to 48 h after labelling. Labelled cells were injected into the cavity of the left or right cardiac ventricle in mice. Scintigraphic images were acquired 24 h later. Organ samples were harvested to determine the tissue-specific activity.

RESULTS

Labelling efficiency was 75 +/- 14%. Cellular retention of incorporated (111)In after 48 h was 18 +/- 4%. Percentage viability after 48 h was 90 +/- 1% (control), 58 +/- 7% (low dose) and 48 +/- 8% (high dose) (p<0.0001). Numbers of viable cells after 48 h (normalised to 0 h) were 249 +/- 51% (control), 42 +/- 8% (low dose) and 32 +/- 5% (high dose) (p<0.0001). Cells accumulated in the spleen (86.6 +/- 27.0% ID/g), bone marrow (59.1 +/- 16.1% ID/g) and liver (30.3 +/- 9.5% ID/g) after left ventricular injection, whereas most of the cells were detected in the lungs (42.4 +/- 21.8% ID/g) after right ventricular injection.

CONCLUSION

Radiolabelling of haematopoietic progenitor cells with (111)In-oxine is feasible, with high labelling efficiency but restricted stability. The integrity of labelled cells is significantly affected, with substantially reduced viability and proliferation and limited migration after systemic transfusion.

Humoral and cellular factors responsible for coronary collateral formation

Clinical observations suggest that patients with coronary artery disease (CAD) display a marked heterogenerty in collateral formation despite similar degrees of coronary obstruction. The development of coronary collaterals helps protect the myocardium from ischemic damage, yet the factors responsible for collateral formation are poorly understood. To better understand the biochemical and cellular mechanisms of collateral artery formation, monocyte function and circulating levels of pro- and antiangiogenic factors were measured in 101 patients with angiographically assessed CAD and extensively developed (score 2, n = 33) or absent (score 0, n = 68) collateral circulations. Compared with patients with score 0, those with score 2 were slightly older and had more advanced CAD. The score 2 group was also more likely to have had a previous myocardial infarction or coronary artery bypass grafting and a family history of CAD. At the same time, there were no significant differences between groups with regard to circulating levels of vascular endothelial growth factor-A(165), platelet-derived growth factor-betabeta, fibroblast growth factor-2, fibroblast growth factor-4, hepatocyte growth factor, tumor necrosis factor-alpha, interleukin-1beta, endostatin, matrix metalloproteinase-9, promatrix metalloproteinase-1, and CD40 ligand. Monocytes isolated from patients with score 2 and 0 collateral circulations demonstrated no differences in migration assays. However, adhesion to fibrinogen and collagen was significantly higher for monocytes from patients with score 0 (p = 0.05 and 0.04, respectively). In conclusion, these data suggest that the degree of coronary collateral formation is not determined by differences in systemically measurable levels of pro- or antiangiogenic factors assessed in this study. Rather, cellular properties, such as cell adhesion, or genetic differences between patients may be the driving force for collateral development.

Therapeutic angiogenesis by ex vivo expanded erythroid progenitor cells

Recent reports have demonstrated that erythroid progenitor cells contain and secrete various angiogenic cytokines. Here, the impact of erythroid colony-forming cell (ECFC) implantation on therapeutic angiogenesis was investigated in murine models of hindlimb ischemia. During the in vitro differentiation, vascular endothelial growth factor (VEGF) secretion by ECFCs was observed from day 3 (burst-forming unit erythroid cells) to day 10 (erythroblasts). ECFCs from day 5 to day 7 (colony-forming unit erythroid cells) showed the highest VEGF productivity, and day 6 ECFCs were used for the experiments. ECFCs contained larger amounts of VEGF and fibroblast growth factor-2 (FGF-2) than peripheral blood mononuclear cells (PBMNCs). In tubule formation assays with human umbilical vein endothelial cells, ECFCs stimulated 1.5-fold more capillary growth than PBMNCs, and this effect was suppressed by antibodies against VEGF and FGF-2. Using an immunodeficient hindlimb ischemia model and laser-Doppler imaging, we evaluated the limb salvage rate and blood perfusion after intramuscular implantation of ECFCs. ECFC implantation increased both the salvage rate (38% vs. 0%, P < 0.05) and the blood perfusion (82.8% vs. 65.6%, P < 0.01). In addition, ECFCs implantation also significantly increased capillaries with recruitment of vascular smooth muscle cells and the capillary density was 1.6-fold higher than in the control group. Continuous production of human VEGF from ECFCs in the skeletal muscle was confirmed at least 7 days after the implantation. Implantation of ECFCs promoted angiogenesis in ischemic limbs by supplying angiogenic cytokines (VEGF and FGF-2), suggesting a possible novel strategy for therapeutic angiogenesis.

The Prostacyclin Analog Beraprost Sodium Augments the Efficacy of Therapeutic Angiogenesis Induced by Autologous Bone Marrow Cells

Implantation of autologous bone marrow (BM) mononuclear cells (MNCs) has been shown to augment neovascular formation in ischemic tissues in experimental animals and in humans. Prostaglandin derivatives improve the symptoms of patients with critical limb ischemia, possibly by their vasodilating and antiplatelet actions. We therefore examined whether therapeutic angiogenesis by implantation of autologous BM-MNCs would be enhanced by beraprost sodium (BPS), using a rabbit ischemic hindlimb model. Ischemia was induced by surgical resection of the left femoral artery. Twenty-five New Zealand white rabbits were divided into four groups. The first group (BM group, n = 4) received autologous BM-MNCs (2 x 10(6)/animal) implanted into the ischemic tissue 1 week after limb ischemia. The second group (BM+BPS group, n = 8) received BPS injected into the dorsal skin (300 microg/kg daily) starting 1 week before limb surgery. This group received BM-MNC implantation 1 week after surgery. Daily injection of BPS was continued until the end of the protocol. The third group (BPS group, n = 8) received BPS injected into the dorsal skin (600 microg/kg daily) starting 1 week before limb surgery. The fourth group received saline as a control (n = 4). The extent of angiogenesis in the ischemic hindlimb was assessed using the angiographic score (AS), ischemic/normal limb calf blood pressure ratio (CBPR), and tissue capillary density. Four weeks after limb ischemia, the ischemic/normal CBPR was highest in the BM+BPS group, followed by the BPS, BM, and control groups (0.56 +/- 0.16, 0.51 +/- 0.25, 0.44 +/- 0.15, and 0.30 +/- 0.10, respectively). The AS was also the greatest in the BM+BP group, followed by the BM, BP, and S group (1.63 +/-0.21, 1.31 +/- 0.25, 1.26 +/- 0.21 and 0.80 +/- 0.10, respectively). The TCD was greatest in the BM+BP group, followed in by the BM, BP, and S group? (46 +/- 4.1, 34 +/- 0.7, 33 +/- 6.9, and 19 +/- 1.8 per field, respectively). BP treatment is an effective means to enhance the efficacy of therapeutic angiogenesis induced by autologous BM-MNCs implantation in ischemic hindlimb tissues.

Administration of Ex Vivo-expanded Bone Marrow-derived Endothelial Progenitor Cells Attenuates Focal Cerebral Ischemia-reperfusion Injury in Rats

OBJECTIVE

This study aimed to examine early effects of ex vivo-expanded bone marrow-derived endothelial progenitor cells (EPCs) on focal cerebral ischemia-reperfusion injury.

METHODS

EPCs were obtained from mononuclear cells of autologous bone marrow of a rat. After culture on fibronectin-coated dishes for 10 to 14 days, 2.5 x 10 cells of EPCs were administered transarterially after 90 minute occlusion of the middle cerebral artery.

RESULTS

Administration of EPCs significantly reduced both the infarct volume and the scores of neurological deficits at 24 and 48 hours. EPCs administered 2 hours after insult did not reduce infarct volume, but attenuated neurological deficits at 24 hours. Administration of EPCs significantly reduced the number of myeloperoxidase-immunoreactive cells in the ischemic lesion at 24 hours and increased regional cortical blood flow at 48 hours. EPCs were observed in the ischemic hemisphere and around the endothelial layer of the pial arteries. Most of them expressed endothelial nitric oxide synthase.

CONCLUSION

Administration of ex vivo-expanded bone marrow-derived EPCs reduced infarct volume and neurological deficits in acute focal brain ischemia-reperfusion injury caused, at least in part, by attenuation of endothelial dysfunction.

Arteriogenesis: Noninvasive Quantification with Multi–Detector Row CT Angiography and Three-dimensional Volume Rendering in Rodents

PURPOSE

To evaluate two-dimensional (2D) multi-detector row computed tomographic (CT) angiography and three-dimensional (3D) volume rendering for depiction of patterns of arterial growth and quantification of blood vessel density and volume.

MATERIALS AND METHODS

The institutional animal care and use committee approved this study. The right femoral artery and its branches were ligated and excised in 16 inbred Lewis rats; animals were randomly assigned to receive 70 microL Dulbecco's modified Eagle's medium (DMEM) or 1.5 x 10(7) bone marrow-derived mononuclear cells (BMC) from isogenic donor rats in 70 microL DMEM. At 2 weeks, CT angiography was performed with injection of 0.45 mL barium sulfate suspension at 0.7 mL/min, followed by silver staining. Number of blood vessels, area, mean area, volume, and blood vessel size distribution derived from digitally subtracted 2D CT angiographic sections were quantified; 3D images were reconstructed. Two-way analysis of variance and paired and unpaired Student t tests were performed.

RESULTS

CT angiography showed two patterns of arterial growth: collateral arterial formation and branching arteriogenesis. Two-way analysis of variance indicated that differences within subjects (ischemic vs nonischemic legs) and between subjects (BMC vs DMEM treatment) were significant for total blood vessel area, total blood vessel volume, and mean of blood vessel area (P < .001). In the BMC group, there were significantly more arteries (mean, 241.6 +/- 77.0 [standard deviation] vs 196.4 +/- 75.2, P = .028), but mean cross-sectional area of these arteries was smaller in ischemic versus nonischemic legs (5.4 mm(2) +/- 1.2 vs 6.8 mm(2) +/- 1.3, P = .006). Total arterial area and volume did not differ significantly between ischemic and nonischemic legs.

CONCLUSION

BMC injection had a substantial effect on arteriogenesis, with normalization of total arterial area and volume in the BMC group; this effect was successfully depicted.

Utilização de células-tronco de medula óssea para tratamento de isquemia crítica de membro inferior

Relatamos o caso de um paciente masculino de 49 anos, portador de oclusão embólica de todas as artérias da perna esquerda. Após múltiplas e fracassadas tentativas de revascularização e, também, simpatectomia lombar em outros serviços, chegou a nós com indicação de amputação no nível de perna. Propusemos o implante de células-tronco autógenas de medula óssea na panturrilha. Obteve-se um excelente resultado, com a supressão da dor em repouso, melhora da hipotermia e palidez, elevação do índice tornozelo/braço, da velocidade sistólica de pico, dos índices cintilográficos e angiográficos e sensível melhora na granulação no local da amputação do quarto e quinto pododáctilo.

Stem cell biology for vascular regeneration

The isolation of endothelial progenitor cells (EPCs) derived from bone marrow (BM) was one epoch-making event for the recognition of neovessel formation in adults occurring as physiological and pathological responses. The finding that EPCs home to sites of neovascularization and differentiate into endothelial cells (ECs) in situ is consistent with vasculogenesis, a critical paradigm that has been well described for embryonic neovascularization, but proposed recently in adults in which a reservoir of stem or progenitor cells contribute to vascular organogenesis. EPCs have also been considered as therapeutic agents to supply the potent origin of neovascularization under pathological conditions. This chapter highlights an update of EPC biology as well as its potential use for therapeutic regeneration.

Therapeutic effects of concurrent autologous bone marrow cell infusion and metabolic intervention in ischemia-induced angiogenesis in the hypercholesterolemic mouse hindlimb

Lower-limb ischemia is a major health problem especially when associated to hypercholesterolemia. Because of the absence of effective treatment in the advanced stages of the disease, amputation is undertaken to alleviate unbearable symptoms. Since tissue ischemia and hypercholesterolemia are associated with an overwhelming generation of oxygen radicals, metabolic intervention with antioxidants and l-arginine can induce beneficial effects beyond those achieved by a novel therapeutic approach represented by the use of autologous bone marrow cells (BMCs). The protective effect of BMCs and vascular protection by metabolic cotreatment (1.0% vitamin E added to the chow, 0.05% vitamin C and 6% l-arginine added to the drinking water) were examined in ischemia-induced angiogenesis in the hypercholesterolemic mouse hindlimb. Intravenous BMC therapy improved blood flow and increased capillary densities. This beneficial effect was amplified by metabolic cotreatment, an intervention inducing vascular protection, at least in part, through the nitric oxide pathway, reduction of systemic oxidative stress and macrophage activation.

Autoperipheral blood mononuclear cell transplantation improved giant ulcers due to chronic arteriosclerosis obliterans

We report the case of a 74-year-old man with Fontaine stage IV chronic arteriosclerosis obliterans who had been suffering from inveterate giant skin ulcers on the dorsum and heel of the right foot. As conventional medical treatments had not improved these ulcers and surgical treatment was considered unfeasible, amputation of the right lower limb below the knee appeared to represent the only option. The patient was admitted to Tottori University Hospital to attempt a new angiogenic therapy using auto-mononuclear cell transplantation to avoid amputation. On admission, neither right ankle blood pressure nor transcutaneous partial pressure of oxygen at the right toe were detectable. The patient had a history of multiple cerebral infarctions, and collection of mononuclear cells from bone marrow was considered too difficult, so collection of peripheral blood mononuclear cells was selected. Transcutaneous partial pressure of oxygen and skin temperature in the treated limb started to improve from 2 weeks after implantation. Ulcer size was recognizably reduced by 1 month after treatment. Partial auto-skin implantation on the right heel was performed 2 months after treatment, and the giant skin ulcer was finally completely covered. No adverse effects were noted during follow-up lasting 1 year. These results suggest that peripheral blood mononuclear cell implantation may offer a suitable alternative rescue therapy for patients with critical limb ischemia whose general condition is not good.

G-CSF and AMD3100 mobilize monocytes into the blood that stimulate angiogenesis in vivo through a paracrine mechanism

There is compelling evidence that circulating angiogenic cells exist that are able to home to sites of vascular injury and stimulate angiogenesis. However, the number of angiogenic cells in the blood is low, limiting their delivery to sites of ischemia. Treatment with certain cytokines may mobilize angiogenic cells into the blood, potentially circumventing this limitation. Herein, we show that treatment with granulocyte colony-stimulating factor (G-CSF) or AMD3100, a novel CXCR4 antagonist, significantly stimulated angiogenesis in a murine model of acute hindlimb ischemia. The kinetics of angiogenic-cell mobilization by these agents appears to be distinct, with more rapid revascularization observed in AMD3100-treated mice. Combination treatment with G-CSF and AMD3100 resulted in the earliest and most complete recovery in blood flow to the ischemic hindlimb. Adoptive transfer of mobilized blood mononuclear cells, while potently stimulating angiogenesis, did not result in the significant incorporation of donor cells into the neoendothelium. Cell-fractionation studies showed that it is the monocyte population in the blood that mediates angiogenesis in this model. Collectively, these data suggest that monocytes mobilized into the blood by G-CSF or AMD3100 stimulate angiogenesis at sites of ischemia through a paracrine mechanism.

Expansion of Canine Bone Marrow-Derived Endothelial Progenitor Cells and Dynamic Observation

We cultured bone marrow-derived endothelial progenitor cells by a simple ex vivo expansion method and observed the expansion efficacy. Bone marrow mononuclear cells from five mongrel adult dogs were cultured with EGM-2MV medium in culture flasks coated with fibronectin. Morphology was observed with phase contrast microscopy, and a growth curve was constructed to evaluate the efficacy of expansion. Incorporation of Dil-ac-LDL was tested to evaluate the function. At different time points, immunocytochemical staining for flk-1, CD133, and factor VIII-related antigens was done and compared to staining of endothelial cells and mesenchymal stem cells and percentages of CD133, vascular endothelial growth factor receptor 2 (VEGFR-2), and the double-positive cells measured with flow cytometry to identify the quality and efficacy of expansion. Cluster-like attached cells grew to confluence at an average time of 10 days, and the mean number of cells harvested from 1 mL of bone marrow was (1.3 +/- 0.3) x 10(6). The cells presented a cobblestone-like appearance and took up Dil-ac-LDL. Immunocytochemistry showed that flk-1, CD133, and factor VIII-related antigens were positive. Flow cytometry showed that VEGFR-2 and CD133 double-positive cells augmented 242-fold at the tenth day. Ex vivo expansion can effectively proliferate endothelial progenitor cells from bone marrow; the expansion efficacy could meet the requirements for tissue engineering of blood vessels.

Therapeutic angiogenesis by bone marrow implantation for critical hand ischemia in patients with peripheral arterial disease: a pilot study

OBJECTIVE

Implantation of bone marrow mononuclear cells (BM-MNCs), including endothelial progenitor cells, into ischemic lower limbs has been shown to improve symptoms in patients with peripheral arterial diseases (PAD). This study investigated whether BM-MNC implantation (BMI) is also effective for the ischemic hands of these patients.

METHODS

Seven PAD patients with hand ischemia were enrolled: six patients had thromboangiitis obliterans and one had collagen disease. All seven had symptoms involving either resting pain or non-healing ischemic ulcers of the hand. Approximately 600 mL of MNCs were separated from BM and concentrated to a final volume of 40-50 mL, which were injected into ischemic hands. Ischemic status was evaluated by measuring the digital/brachial pressure index (DBI), visual analog pain scale, and the healing of ulcers before and 6 months after BMI.

RESULTS

The mean number of implanted MNCs, CD34-positive cells, and CD34,133-positive cells was 3.67 +/- 0.53 x 10(9), 4.94 +/- 2.45 x 10(7), and 2.52 +/- 1.57 x 10(7), respectively. Mean DBI in those patients was 0.15 +/- 0.30 before BMI and significantly increased to 0.67 +/- 0.19 at 6 months after BMI (p = 0.004). All patients also showed improvement of pain scale and ischemic ulcers. There was no significant correlation between the number of implanted cells and improvement in the degree of DBI or the pain scale.

CONCLUSION

Autologous BMI could be a promising and safe method of therapeutic angiogenesis for critical hand ischemia in PAD patients.

Vascularization in tissue remodeling after rat hepatic necrosis induced by dimethylnitrosamine

We observed postnecrotic tissue remodeling to examine vascularization in adult rat livers. Livers, bone marrow, and peripheral blood from rats at 24 h to 14 days after an injection of dimethylnitrosamine (DMN) were examined by light microscopic, immunohistochemical, and ultrastructural methods. Numerous ED-1 (a marker for rat monocytes/macrophages)-positive round mononuclear cells infiltrated in the necrotic areas at 36 h after DMN treatment. On day 5, when necrotic tissues were removed, some of the cells were transformed from round to spindle in shape. On day 7, these cells were contacted with residual reticulin fibers and became positive for SE-1, a marker of hepatic sinusoidal endothelial cells and Tie-1, an endothelial cell-specific surface receptor, associated with frequent occurrence of ED-1/SE-1 and ED-1/Tie-1 double-positive spindle cells. Ultrastructurally, the spindle cells simultaneously showed phagocytosis and endothelial cell-like morphology. With time necrotic areas diminished, and on day 14, the necrotic tissues were almost replaced by regenerated liver tissues and thin bundles of central-to-central bridging fibrosis. Bone marrow from 12 h to day 2 showed an increase of BrdU-positive mononuclear cells. Some of them were positive for ED-1. The BrdU-labeled and ED-1-positive cells appeared as early as 12 h after DMN injection and reached a peak in number at 36 h. They were similar in structure to ED-1-positive cells in necrotic liver tissues. These findings suggest that round mononuclear ED-1-positive cells proliferate first in bone marrow after DMN treatment, reach necrotic areas of the liver through the circulation, and differentiate to sinusoidal endothelial cells. Namely, hepatic sinusoids in DMN-induced necrotic areas may partly be reorganized possibly by vasculogenesis.

Transplantation of endothelial progenitor cells transferred by vascular endothelial growth factor gene for vascular regeneration of ischemic flaps

BACKGROUND

Neovascularization occurs through two mechanisms: angiogenesis and vasculogenesis. Therefore, there are two strategies to promote neovascularization: therapeutic angiogenesis and therapeutic vasculogenesis (endothelial progenitor cells therapy).

MATERIALS AND METHODS

In this study, we examined whether or not endothelial progenitor cells combined with vascular endothelial growth factor (VEGF) gene therapy is useful for ischemia surgical flaps in vivo. At the same time, we quantitatively compared the neovascularization ability of transplanted endothelial progenitor cells (EPCs) transducted with VEGF165 gene and EPCs alone. EPCs were isolated from cord blood of healthy human volunteers, cultured in vitro for 7 days and identified by immunofluorescence. After transduced with VEGF165 gene in vitro, proliferative activity of EPCs was assessed using MTT assay. CM-DiI was used to trace EPCs in vivo 4 days after injection of 5 x 10(5) VEGF-transduced EPCs(VEGF-transduced EPCs group, n = 10), 5 x 10(5) EPCs (non-transduced EPCs group, n = 10) in 500 microL EBM-2 media, or 500 microL EBM-2 media (EBM-2 media group, n = 10) local, a cranially based flap was elevated on the back of nude mice. The percent flap survival, neovasculariztion and blood flow recovery of flaps was detected.

RESULTS

EPCs expressed cell markers CD34, KDR, and CD133. A statistically significant increase in percent flap survival was observed in mice of VEGF-transduced EPCs group as compared with that of non-transduced EPCs group: 67.99 +/- 6.64% versus 59.43 +/- 4.69% (P < 0.01), and 41.24 +/- 2.44% in EBM-2 media group (P < 0.01). The capillary density and blood flow recovery of flaps in VEGF-transduced EPCs group were both improved. CM-DiI-labeled VEGF-transduced EPCs were observed in vivo and the numbers of cells increased.

CONCLUSION

EPCs from human cord blood can increased neovascularization of ischemic flaps and augmented the survival areas, and VEGF-transduced EPCs have more powerful ability of promoting neovascularization in animal model of ischemic flaps.

[Treatment of lower limb ischemia with combination of traditional Chinese medicine and transplantation of autologous bone marrow mononuclear cells: a report of 23 cases]

OBJECTIVE

To evaluate the therapeutic effect of transplantation of autologous bone marrow mononuclear cells combined with traditional Chinese medicine for the treatment of limb ischemia.

METHODS

Twenty-three patients with limb ischemia were treated. G-CSF was used to stimulate the bone marrow. The mononuclear cells were separated from the aspirated bone marrow fluid in the stem cell studio. The cell amount was above 1x10(9). The transplantation was performed by the way of intra-muscular multi-injection. Traditional Chinese medicine for replenishing qi to activate blood was prescribed from the first day after operation. The pain, poikilothermia, ulcer or necrosis and ankle/brachial index (ABI) of the ischemic limb were evaluated before and after the treatment.

RESULTS

The pain score and poikilothermia score decreased one month after the transplantation, with distinct differences as compared with the scores before the treatment (P<0.05). The ABI increased gradually after the treatment, and one month after the treatment, it was 0.15 higher than that before the treatment.

CONCLUSION

Transplantation of autologous bone marrow mononuclear cells combined with traditional Chinese medicine can decrease the symptoms and signs of severe lower limb ischemia effectively, and improve the circulation of the ischemic area.

Direct intramyocardial percutaneous delivery of autologous bone marrow in patients with refractory myocardial angina

BACKGROUND

Intramyocardial injection of autologous bone marrow (ABM) may induce angiogenesis. We tested the safety and feasibility of catheter-based direct percutaneous intramyocardial delivery of ABM in patients with refractory angina pectoris.

METHODS

Ten patients (9 men, 67 +/- 8 years) with refractory angina (Canadian Cardiovascular Society class III-IV) and documented myocardial ischemia were enrolled. After left ventricular electromechanical mapping, freshly aspirated and filtered ABM was percutaneously injected into target myocardial ischemic areas. Clinical symptoms (as assessed according to the Canadian Cardiovascular Society class), quality of life, and myocardial perfusion were evaluated before the procedure and through the follow-up.

RESULTS

In all patients, ABM was successfully injected into the target regions. No periprocedural complications occurred. At 12 months, no major cardiac events (death, acute myocardial infarction, stroke, and malignant ventricular arrhythmias) occurred. Severity of angina improved of > or = 2 classes in 3 patients. Quality of life showed a significant improvement in all patients. Myocardial perfusion in the target regions improved in 4 of 8 patients.

CONCLUSIONS

Direct percutaneous intramyocardial delivery of ABM appears feasible and safe. Further evaluation is warranted to test its clinical efficacy.

Therapeutic angiogenesis

Still a long way off

Transplantation of umbilical cord blood-derived endothelial progenitor cells: a promising method of therapeutic revascularisation

Therapeutic neovascularisation by endothelial progenitor cells (EPCs) mediated vascular regeneration is becoming a novel option for the treatment of ischaemic diseases. Recently, human umbilical cord blood (CB) has been found to contain a large number of EPCs and transplantation of CB EPCs led to a successful salvage of the ischaemic limbs through improvement in blood perfusion, indicating the feasibility of using CB cells for therapeutic revascularisation. This review will summarise recent studies in therapeutic revascularisation using CB cells and discuss the potential clinical utilisation of CB cells in ischaemic diseases.

Characteristics of rat bone marrow cells differentiated into a liver cell lineage and dynamics of the transplanted cells in the injured liver

BACKGROUND

Bone marrow cells (BMCs) have been shown to differentiate into a liver cell lineage, but little is known about their dynamics following transplantation. BMCs were cultured to investigate the expression of liver-specific genes in vitro and transplanted into in vivo liver-injury models to elucidate their dynamics in the liver.

METHODS

The mRNA expression of various liver-specific genes in BMCs cocultured with hepatocytes was analyzed using reverse transcription-polymerase chain reaction. BMCs from transgenic rats expressing green fiuorescent protein were transplanted into the spleen of rat liver-injury models induced with 2-acetylaminofiuorene (2-AAF) or carbon tetrachloride (CCl4). BMCs were also transplanted directly into livers treated with CCl4 to determine which route is better for transplantation.

RESULTS

BMCs differentiated into a liver cell lineage in vitro and expressed mRNAs consistent with mature hepatocytes, including albumin. The transplanted BMCs were found in the liver in the CCl4-induced injury model, but not in the 2-AAF-induced model. The hepatocyte growth factor and fibroblast growth factor mRNA levels in the liver were significantly higher in the CCl4-induced model than in the 2-AAF-induced model. Migration of BMCs to the liver was more effective following injection into the liver, rather than into the spleen.

CONCLUSIONS

Cultured BMCs differentiated into a liver cell lineage are a potential source for cell transplantation. Transplantation is successful in the severely injured liver with a high level of expression of mRNAs for growth factors. Injection of BMCs directly into the liver is the preferred route of administration.

Therapeutic angiogenesis by autologous bone marrow cell implantation for refractory chronic peripheral arterial disease using assessment of neovascularization by 99mTc-tetrofosmin (TF) perfusion scintigraphy

We investigated efficacy and safety of implantation of autologous bone marrow mononuclear cells plus platelets, including endothelial progenitor cells (EPCs), for recovering refractory chronic peripheral arterial disease (PAD) using visual and quantitative analyses by 99mTc-tetrofosmin (TF) perfusion scintigraphy, and also investigated various quantitative assessments objectively. We performed 12 consecutive cases and 19 limbs and hands with severe chronic PAD that were almost Fontaine class IV (11/12 cases, about 92%) in this trial. This treatment was very effective in relieving severe pain of PAD, especially for Buerger's disease. We used a visual analog scale (VAS) for measurement of pain level. The maximum pain level before implantation was 66.5+/-5.0 mm, and it decreased to 12.1+/-2.2 mm after implantation (p < 0.001). Rest pain in legs and fingers was resolved in 11 cases (11/12 cases, 92%). All patients could measure pain-free walking time on a treadmill, which improved remarkably (140+/-53 s before implantation vs. 451+/-74 s after implantation, p = 0.034). Resting ankle brachial pressure index (ABI) in legs implanted with bone marrow mononuclear cells was also improved (0.65+/-0.08 before implantation vs. 0.73+/-0.07 after implantation, p = 0.055). According to 99mTc-TF perfusion scintigraphy, the proximal area (region from knee to ankle) was 1.32+/-0.10 before implantation versus 1.56+/-0.11 after implantation (p = 0.007). 99Tc-TF perfusion scintigraphy in the distal area (region from ankle to end of toes, or from wrist to end of fingers) was 0.79+/-0.06 before implantation versus 0.83+/-0.06 after implantation (p = 0.29). Ischemic legs and hands that were injected showed increased perfusion blood flow. 99mTc-TF perfusion scintigraphy was effective to estimate visual and quantitative analysis of collateral vessels in neovascularization. We were successful with this new treatment for the most severe, chronic PAD that was not curable by any of the current treatments. Thus, this therapeutic angiogenesis could be a new strategy for saving severe ischemic limbs and hands.

Acceleration of endothelial-like cell differentiation from CD14+ monocytes in vitro

OBJECTIVE

In vitro differentiation of endothelial cells has potential applications in vascular tissue engineering and cell-based therapy for many diseases. The objective of this study was to develop a new strategy that utilizes cytokines and lipopolysaccharide (LPS) to accelerate endothelial-like cell differentiation from peripheral blood CD14(+) monocytes.

METHODS

Peripheral blood CD14(+) monocytes were purified with immunobeads and cultured with an angiogenic growth factor-rich growth medium (EGM-2) with or without initial treatment of LPS in combination of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) for 4 days (the day 4 cultures). The cells were then continuously cultured in EGM-2 medium for an additional 4 or 10 days (the day 8 or day 14 cultures). Cell markers were determined by flow cytometry analysis and immunofluorescence staining. Cytokine/chemokine profile was studied by Bio-Plex immunoassay.

RESULTS

In the group of initial treatment of LPS in combination with GM-CSF, IL-4, and EGM-2, the majority of suspended CD14(+) monocytes were attached and changed their morphology to endothelial-like cells, which expressed high levels of endothelial cell markers CD31, von Willebrand factor, and vascular endothelial growth factor receptor-1 as well as two major endothelial tight junction proteins zonula occludens -1 and occludin in the day 8 cultures. Endothelial nitric oxide synthase expression was substantially increased. Endothelial-like cells were also able to uptake acetylated low-density lipoprotein and bind to Ulex europeus lectin. In addition, endothelial-like cells showed a unique cytokine/chemokine profile with substantial increases of macrophage inflammatory protein-1beta, IL-6, granulocyte colony-stimulating factor, and IL-8.

CONCLUSION

Initial treatment of LPS in combination with GM-CSF, IL-4, and EGM-2 is an effective strategy for acceleration of endothelial-like cell differentiation from peripheral blood CD14(+) monocytes in vitro.

Beneficial effects of concurrent autologous bone marrow cell therapy and metabolic intervention in ischemia-induced angiogenesis in the mouse hindlimb

Lower-limb ischemia is a major health problem. Because of the absence of effective treatment in the advanced stages of the disease, amputation is undertaken to alleviate unbearable symptoms. Novel therapeutic approaches include the intramuscular use of autologous bone marrow cells (BMCs). Because tissue ischemia is associated with an overwhelming generation of oxygen radicals and negative effects due to perturbed shear-stress, metabolic intervention with antioxidants and l-arginine could potentially induce beneficial effects beyond those achieved by BMCs. The protective effect of autologous BMCs and vascular protection by metabolic cotreatment (1.0% vitamin E added to the chow and 0.05% vitamin C and 6% l-arginine added to the drinking water) were examined in ischemia-induced angiogenesis in the mouse hindlimb, a model of extensive acute peripheral arterial occlusion. i.v. BMC therapy improved blood flow and increased capillary densities and expression of Ki-67, a proliferation-associated protein. This beneficial effect was amplified by metabolic cotreatment, an intervention inducing vascular protection, at least in part, through the nitric oxide pathway, reduction of systemic oxidative stress, and macrophage activation. Therefore, although a cautious approach is mandatory when experimental findings are extended to human diseases, autologous BMCs together with metabolic intervention could be an effective clinical treatment for peripheral arterial disease.

Granulocyte colony-stimulating factor promotes neovascularization by releasing vascular endothelial growth factor from neutrophils

The granulocyte colony-stimulating factor (G-CSF) promotes angiogenesis. However, the exact mechanism is not known. We demonstrate that vascular endothelial growth factor (VEGF) was released by Gr-1+CD11b- neutrophils but not Gr-1-CD11b+ monocytes prestimulated with G-CSF in vitro and in vivo. Similarly, in vivo, concomitant with an increase in neutrophil numbers in circulation, G-CSF augmented plasma VEGF level in vivo. Local G-CSF administration into ischemic tissue increased capillary density and provided a functional vasculature and contributed to neovascularization of ischemic tissue. Blockade of the VEGF pathway abrogated G-CSF-induced angiogenesis. On the other hand, as we had shown previously, VEGF can induce endothelial progenitor cell (EPC) mobilization. Here, we show that G-CSF also augmented the number of circulating VEGF receptor-2 (VEGFR2) EPCs as compared with untreated controls. Blocking the VEGF/VEGFR1, but to a much lesser extent, the VEGF/VEGFR2 pathway in G-CSF-treated animals delayed tissue revascularization in a hindlimb model. These data clearly show that G-CSF modulates angiogenesis by increasing myelomonocytic cells (VEGFR1+ neutrophils) and their release of VEGF. Our results indicated that administration of G-CSF into ischemic tissue provides a novel and safe therapeutic strategy to improve neovascularization.

Therapeutic neovascularization by autologous transplantation with expanded endothelial progenitor cells from peripheral blood into ischemic hind limbs

AIM

To investigate the hypothesis that transplantation with expanded autologous endothelial progenitor cells (EPC) could enhance neovascularization.

METHODS

Peripheral blood mononuclear cells (PB-MNC) isolated from New Zealand White rabbits were cultured in vitro. At d 7, the adherent cells were collected for autologous transplantation. Rabbits with severe unilateral hind limb ischemia were randomly assigned to receive phosphate-buffered saline or expanded EPC in phosphate-buffered saline, administered by intramuscular injection in 6 sites of the ischemic thigh at postoperative d 7. Neovascularization was monitored by using the calf blood pressure ratio to indicate tissue perfusion, digital subtraction angiography to identify collateral vessel development and histological analysis of capillary density in the ischemic limb at d 35 after surgery.

RESULTS

Autologous EPC transplantation produced significant amelioration in ischemic hind limbs, as indicated by a greater calf blood pressure ratio (0.52+/-0.04 vs 0.42+/-0.05, P<0.01), angiographic score (1.44+/-0.06 vs 0.98+/-0.08, P<0.01) and capillary density in muscle (195.2+/-5.4/mm2 vs 169.4+/-6.4/mm2, P<0.05), than controls.

CONCLUSION

Transplantation of autologous expanded EPC can promote neovascularization in ischemic hindlimbs.

Circulating endothelial progenitor cells and coronary collaterals in patients with non-ST segment elevation myocardial infarction

BACKGROUND

Endothelial progenitor cells (EPCs) are bone marrow-derived cells that are augmented in response to ischemia and incorporated into neovascularization sites. We sought to determine whether circulating EPCs are related to collateral formation following non-ST segment elevation myocardial infarction (NSTEMI).

METHODS

Twenty patients who underwent percutaneous coronary intervention (PCI) within a week of NSTEMI were divided into two groups: patients without collaterals (coll-, n=10) and patients with Rentrop grade 3--4 collaterals (coll+, n=10). Blood samples were drawn before PCI and 24+/- 2 h after PCI. EPC colonies were grown from peripheral blood mononuclear cells, characterized, and counted. Using flow cytometry the percentage of cells co expressing vascular endothelial growth factor receptor-2 and CD 133 was determined.

RESULTS

The coll+ group had higher degree of culprit vessel stenosis and lower initial thrombolysis in myocardial infarction flow grade. The relative number of EPCs before PCI was significantly higher in the coll+ group than in the coll- group (1.49 +/- 0.9% vs. 0.77+/- 0.4%, p= 0.045). There were no significant intergroup differences in the number of EPC colony-forming cells. The number of EPC colonies increased in the coll- group after PCI (9.5 +/- 4.8 to 14.0 +/- 5.9/10(6) cells, p=0.01).

CONCLUSIONS

This study supports an association between circulating EPC levels and collateral formation in patients with an NSTEMI.

Neovascularization and bone regeneration by implantation of autologous bone marrow mononuclear cells

We examined whether transplantation of autologous bone marrow mononuclear cells (BM-MNCs) can augment neovascularization and bone regeneration of bone marrow in femoral bone defects of rabbits. Gelatin microspheres containing basic fibroblast growth factor (bFGF) were prepared for the controlled release of bFGF. To evaluate the in vivo effect of implanted BM-MNCs, we created bone defects in the rabbit medial femoral condyle, and implanted into them 5 x 10(6) fluorescent-labeled autologous BM-MNCs together with gelatin microspheres containing 10 microg bFGF on an atelocollagen gel scaffold. The four experimental groups, which were Atelocollagen gel (Col), Col + 5 x 10(6) BM-MNCs, Col + 10 microg bFGF, and Col + 5 x 10(6) BM-MNCs + 10 microg bFGF, were implanted into the sites of the prepared defects using Atelocollagen gel as a scaffold. The autologous BM-MNCs expressed CD31, an endothelial lineage cell marker, and induced efficient neovascularization at the implanted site 2 weeks after implantation. Capillary density in Col + BM-MNCs + bFGF was significantly large compared with other groups. This combination also enhanced regeneration of the bone defect after 8 weeks to a significantly greater extent than either BM-MNCs or bFGF on their own. In summary, these findings demonstrate that a combination of BM-MNCs and bFGF gelatin hydrogel enhance the neovascularization and the osteoinductive ability, resulting in bone regeneration.

Embryonic endothelial progenitor cells expressing a broad range of proangiogenic and remodeling factors enhance vascularization and tissue recovery in acute and chronic ischemia

Clonal embryonic endothelial progenitor cells (eEPCs) isolated from embryonic day 7.5 mice home specifically to hypoxic areas in mouse tumor metastases but spare normal organs and do not form carcinomas. Based on these results, we assessed the potential of eEPCs to enhance vascularization and limit organ dysfunction after ischemia in syngenic and xenotypic organisms. The angiogenic potential of eEPCs was evaluated in chronic ischemic rabbit hindlimbs after regional application by retroinfusion. eEPC treatment improved limb perfusion, paralleled by an increase in capillary density and collateral blood vessel number. Systemic eEPC infusion into mice after ischemic cardiac insult increased postischemic heart output measured by a marked improvement in left ventricle developed pressure and both systolic and diastolic functions. In vitro, eEPCs strongly induced vascular outgrowths from aortic rings. To address the molecular basis of this intrinsic angiogenic potential, we investigated the eEPC transcriptome. Genome-wide Affymetrix GeneChip analysis revealed that the eEPCs express a wealth of secreted factors known to induce angiogenesis, tissue remodeling, and organogenesis that may contribute to the eEPC-mediated beneficial effects. Our findings show that eEPCs induce blood vessel growth and cardioprotection in severe ischemic conditions providing a readily available source to study the mechanisms of neovascularization and tissue recovery.

In vitro differentiation characteristics of cultured human mononuclear cells—implications for endothelial progenitor cell biology

Endothelial progenitor cells (EPCs) have been implicated in the pathogenesis and treatment of cardiovascular disease. By use of quantitative uptake of DiLDL and lectin staining, EPCs have been characterized reliably. However, the exact nature and function of this cell population still remains poorly defined. In an attempt to further clarify the cell surface characteristics of EPCs, mononuclear cells (MNCs) were isolated from human blood and cell surface expression patterns were defined by FACS analysis before and after differentiation for 1-10 days in cell culture. "Classical" double staining for DiLDL and Ulex europaeus increases to 89.2 /- 0.05 after 10 days in culture. Looking at EPC-specific markers by FACS analysis, 0.18 +/- 0.11% of freshly isolated MNCs express CD34, 0.13 +/- 0.08% CD133, 0.59 +/-0.51% VEGFr2, 0.01 +/- 0.02% CD34/VEGFr2, 0.09 +/- 0.05% CD34/CD133, 0.58 +/- 0.13% CD34/CD31, and 0.02 +/- 0.01% CD34/CD146, respectively. Induction of the endothelial phenotype is evidenced by positive staining for VEGFr2, CD146, and CD31, and occurs in co-expression with stem cell markers in less than 2 +/- 0.52% of cultured cells. Expression of CD34 increases to 0.38 +/- 0.10% after 10 days, whereas the CD133(+) cell population shows an initial peak at 24h (0.29 +/- 0.18%) before decreasing to 0.15 +/- 0.02% at day 10. EPCs co-expressing CD34/CD133 increase to 0.19 +/- 0.09% after 10 days, and EPCs double-positive for CD34/VEGFr2 increase to 1.45 +/- 1.03%. Looking at leukocyte, lymphocyte, and monocyte lineage markers, 56.27 +/- 0.15% of freshly isolated MNCs express CD45, 7.13 +/- 0.02% CD14, and 38.65 +/- 0.01% CD3. Over the 10-day culture period, expression of CD45 decreases to 28.48 +/- 0.18%, CD3 to 23.11 +/- 0.02%, and CD14 to 0.09 +/- 0.02%. Cells co-expressing CD3/CD45 decrease from 38.88 +/- 0.33% to 24.86 +/- 2.49% after 10 days in culture. These findings extend present knowledge by showing that human MNCs differentiate at a very low rate to EPCs, while a majority of the cultured cell population remain committed to the leukocyte or lymphocyte lineage. Careful surface marker analysis might be necessary when using in vitro EPC differentiation systems.

Microbubble destruction with ultrasound augments neovascularisation by bone marrow cell transplantation in rat hind limb ischaemia

OBJECTIVE

To examine the effects of microbubble destruction with ultrasound (MB) combined with bone marrow derived mononuclear cell transplantation (BMT) into ischaemic tissues in rat hind limb ischaemia.

METHODS AND RESULTS

Unilateral hind limb ischaemia was surgically induced in Lewis rats. At postoperative day 7, rats were randomly divided into three groups: a vehicle treated group, an ultrasound treated group, and an MB treated group. MB treatment increased vascular endothelial growth factor mRNA as assessed by real time polymerase chain reaction (3.0-fold, p < 0.05). At four weeks, the MB group had increases in laser Doppler blood flow index (LDBFI; 1.2-fold, p < 0.05), angiographically detectable collateral vessels (angiographic score: 1.4-fold, p < 0.01), and capillary to muscle fibre ratio (1.4-fold, p < 0.01) in ischaemic limbs compared with the vehicle treated group. No differences were seen between the vehicle and ultrasound treated groups. Secondly, rats were allocated to vehicle treatment, BMT (5 x 10(6) cells/rat), or a combination of MB and BMT (MB+BMT) at seven days after hind limb ischaemia. BMT treatment significantly increased LDBFI, angiographic score, and capillary to muscle fibre ratio compared with vehicle treatment. Interestingly, MB+BMT treatment produced significantly greater LDBFI (1.2-fold, p < 0.01), angiographic score (1.5-fold, p < 0.01), and capillary to muscle fibre ratio (1.5-fold, p < 0.05) than BMT treatment alone.

CONCLUSIONS

MB may be a useful technique to enhance BMT induced neovascularisation.

Adrenomedullin: angiogenesis and gene therapy

Adrenomedullin (AM) is a potent, long-lasting vasodilator peptide that was originally isolated from human pheochromocytoma. AM signaling is of particular significance in endothelial cell biology since the peptide protects cells from apoptosis, promotes angiogenesis, and affects vascular tone and permeability. The angiogenic effect of AM is mediated by activation of Akt, mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2, and focal adhesion kinase in endothelial cells. Both AM and its receptor, calcitonin receptor-like receptor, are upregulated through a hypoxia-inducible factor-1-dependent pathway under hypoxic conditions. Thus AM signaling plays an important role in the regulation of angiogenesis in hypoxic conditions. Recently, we have developed a nonviral vector, gelatin. Positively charged gelatin holds negatively charged plasmid DNA in its lattice structure. DNA-gelatin complexes can delay gene degradation, leading to efficient gene transfer. Administration of AM DNA-gelatin complexes induces potent angiogenic effects in a rabbit model of hindlimb ischemia. Thus gelatin-mediated AM gene transfer may be a new therapeutic strategy for the treatment of tissue ischemia. Endothelial progenitor cells (EPCs) play an important role in endothelial regeneration. Interestingly, EPCs phagocytose ionically linked DNA-gelatin complexes in coculture, which allows nonviral gene transfer into EPCs. AM gene transfer into EPCs inhibits cell apoptosis and induces proliferation and migration, suggesting that AM gene transfer strengthens the therapeutic potential of EPCs. Intravenous administration of AM gene-modified EPCs regenerate pulmonary endothelium, resulting in improvement of pulmonary hypertension. These results suggest that in vivo and in vitro transfer of AM gene using gelatin may be applicable for intractable cardiovascular disease.

Retinal vascular regeneration

We discuss the potential use of stem cells for therapeutic angiogenesis in the treatment of retinal diseases. We demonstrate that the clinical utility of these EPC may be not limited in the treatment of ischemic retinal diseases but may also have application for the treatment of retinal degenerative disorders and for a form of cell-based gene therapy. One of the greatest potential benefits of bone marrow derived EPC therapy is the possible use of autologous grafts. Nonetheless, potential toxicities and unregulated cell growth will need to be carefully evaluated before this approach is brought to the clinics.

Changing the logic of therapeutic angiogenesis for ischemic disease

The worldwide epidemic of ischemic disease urgently requires innovative treatments. Recently, therapeutic angiogenesis has emerged as a noninvasive supply-side approach, aimed at promoting neovascularization in underperfused tissues through the local delivery of angiogenic growth factors. Successful preclinical studies paved the way for the first clinical trials, with single growth factors given as recombinant proteins or genes. However, clinical results have not matched the initial promises. Our opinion is that the logic of therapeutic angiogenesis needs profound revision. Here, we introduce the concept that pleiotropic agents can stimulate the healing of all the components of ischemic tissue. We also propose prophylactic interventions to delay vascular senescence. The optimization of therapeutic angiogenesis will open unprecedented opportunities for the care of life-threatening ischemic disease.

Improved Survival of Ischemic Random Skin Flaps Through the Use of Bone Marrow Nonhematopoietic Stem Cells and Angiogenic Growth Factors

Surgical skin flaps are frequently used in plastic and reconstructive surgery to repair acquired or congenital defects. Necrosis is a common complication associated with these flaps postoperatively as a result of inadequate blood supply. Stem cells are precursor cells with the potential to differentiate into more specialized cells. Angiogenic factors act to direct cellular differentiation and organization to form new vascular elements. Our theory was that the combination of angiogenic growth factors with stem cells derived from the subject preoperatively would augment neovascularization, thereby increasing blood supply to the flap, which may ultimately improve flap survival. In phase I, 40 Lewis rats were randomized into 4 groups of 10. Random dorsal skin flaps were elevated and treated at the same time. The first group was injected with only medium, the second with stem cells, the third with stem cells and angiogenic factors, and the fourth with angiogenic growth factors. Millimetric measurements of flap viability at 7 and 14 days did not show any statistically significant differences between the studied groups. In phase II, 24 rats were also randomized into 4 groups of 6, but this time were treated 1 week before flap elevation. The viability measurements showed an increased rate of viability in the group in which stem cells and the angiogenic factors were administered simultaneously (84.5% +/- 3.2%) as compared with the unmodified control group (62.6% +/- 7.3%) or to the groups in which only precursor cells (60.4% +/- 7.9%) or angiogenic factors (62.3%+/- 10.1%). Increased blood supply brought by these manipulations is believed translated to increased tissue flap survival. Punch biopsies showed that "green fluorescent protein"-labeled precursor cells was noted to form luminal structures in the treated flaps. The vascular cast of all flaps was filled with Mercox plastic resin. After euthanasia, the soft tissues of the harvested flaps were dissolved and the remaining vascular cast was weighted. The weight-based ratio of the vascular composition was determined. The flaps injected with both stem cells and angiogenic factors showed higher values. We conclude that the administration of bone marrow stem cells with angiogenic factors 1 week before flap creation improves the survival of ischemic random skin flaps.

Cells expressing the stem cell factor receptor, c-kit, contribute to neoangiogenesis in diabetes

While neoangiogenesis in diabetes is of greatest clinical significance in the retina, the pathological formation of new blood vesselsalso develops in other vascular beds in diabetes, including the mesentery of the streptozotocin-induced diabetic rat. However, the contribution of bone marrow-derived cells to this process of vasculogenesis is unknown. In this study, male Sprague-Dawley rats were randomised to receive either streptozotocin or vehicle, and their mesenteric vasculature was examined after three weeks. Origins from bone marrow and endothelial cell differentiation were identified by immunolabelling for the stem cell factor receptor, c-kit and von Willebrand factor (vWF), respectively. Expression for the angiogenic chemokine, stromal derived factor-1 (SDF-1) was assessed by quantitative real-time polymerase chain reaction (PCR). At three weeks, rats with diabetes had a dramatic (190-fold) increase in lectin-labelled blood vessel profiles in the mesenteric bed (p < 0.0001) in association with a five-fold increase in SDF-1 mRNA (p < 0.01). Immunohistochemical studies identified abundant large, ovoid, lumen-forming, c-kit+ cells in the mesentery of diabetic, but not control, rats. Many of these c-kit+ cells also showed positive immunolabelling for vWF, consistent with endothelial differentiation. In conclusion, cells of bone marrow origin contribute to new vessel formation in the diabetic mesentery. This phenomenon may also apply to the neovascularisation that develops at clinically important sites such as in the retina.

Bone marrow mononuclear cell transplantation into heart elevates the expression of angiogenic factors

The expression of angiogenic factors was measured to elucidate the mechanism of angiogenesis after bone marrow stem cells transplantation. The left anterior descending coronary (LAD) artery was ligated in male Lewis rats to induce an acute myocardial infarction (AMI); of which, some rats received bone marrow mononuclear cells transplantation (BMT). The expression of cytokines and their receptors was assessed by RT-PCR. The expression of c-met was upregulated in the AMI animals and was further increased when the animals received BMT (P < 0.01). The other cytokines and their receptors remained unchanged after BMT compared with AMI samples. Normal bone marrow mononuclear cells have higher expression level of hepatocyte growth factor (HGF) than those in normal hearts. In conclusion, BMT could increase the expression of c-met. Not all angiogenic cytokines and their receptors were upregulated after BMT. The higher expression of hepatocyte growth factor in bone marrow may contribute to the upregulation of c-met.

Clinical application of bone marrow implantation in patients with arteriosclerosis obliterans, and the association between efficacy and the number of implanted bone marrow cells

BACKGROUND

There have been a number of recent reports on the use of autologous bone marrow implantation (BMI) in the treatment of peripheral arterial disease, with a clinical response rate of approximately 70%. However, the factors that influence efficacy have not yet been clarified. We have analyzed the relationship between the number of implanted bone marrow cells and the clinical efficacy of BMI.

METHODS AND RESULTS

Eight patients with arteriosclerosis obliterans were treated with BMI. Bone marrow was aspirated from the ilium (500-1,000 ml), the mononuclear cells were separated and then were implanted. The clinical effectiveness of BMI was evaluated by assessing changes in the ankle-brachial pressure index (ABI) and the transcutaneous oxygen pressure (TcO2) between the pre-treatment baseline, with follow-up testing at 4 weeks. These changes were defined as DeltaABI and DeltaTcO2. The mean number of CD34-positive cells was 1.04+/-0.60 x10(6) /kg body weight. There was a strong correlation between the number of CD34-positive cells and DeltaABI (r=0.754, p=0.028).

CONCLUSIONS

It is likely that the number of implanted CD34-positive cells is one of the primary factors that influence the clinical efficacy of BMI.

Angiogenic strategy for human ischemic heart disease: brief overview

In the Western World ischemic coronary disease is the leading cause of morbidity and mortality. Therapeutic approaches mostly aim to restore flow to a localized segment by angioplasty or bypass surgery. Therapeutic angiogenesis and or arteriogenesis describes a strategy where blood vessel formation is induced for the purposes of treating and/or preventing ischemic disease. At present, at least 17 clinical trials of myocardial angiogenesis have been presented involving over 900 patients. Therapeutic angiogenesis makes use of the administration of angiogenic growth factor protein or gene to promote the development of endogenous collateral vessels in ischemic myocardium. Most recently, interest has grown in the potential angiogenesis effects of cell therapy--such as autologous bone marrow cells or cultured stem cells--and there are now several groups initiating phase I/II trials in this area.

Therapeutic myocardial angiogenesis: past, present and future

One of the main goals in the treatment of myocardial ischemia is the development of effective therapy for angiogenesis and neovascularization. The first evidence demonstrating alleviation of myocardial ischemia and increased number of collateral blood vessels was reported in the early 90s following intra-coronary administration of basic fibroblast growth factor protein in canine. This study established the ground for extensive investigations to demonstrate the use of other angiogenic growth factor proteins, genes administered directly or incorporated in viruses, and more recently, endothelial progenitor stem cells (embryonic and adults). The positive results observed in animals failed, in most cases, to repeat themselves in clinical-trials in human patients. Therefore, additional experiments are warranted to allow full understanding of the mechanism underlying new blood vessel formation before further clinical studies are undertaken. This review will explore the milestones of angiogenic investigations and their clinical application.

Transplantation of human umbilical vein endothelial cells improves left ventricular function in a rat model of myocardial infarction

INTRODUCTION

Although cell-based therapy after myocardial infarction (MI) may be beneficial in improving cardiac dysfunction, the underlying mechanisms remain to be clarified. Since human umbilical vein endothelial cells (HUVEC) harbor the potential for transdifferentiation, we studied the functional effects of HUVEC transplantation in a rat model of MI.

METHODS AND RESULTS

HUVEC labeled with BrdU or medium alone were injected into the infarcted area and its margin 4 weeks after ligation of the left coronary artery in cyclosporine-treated rats. BrdU(+) signals could be detected in the area of MI at two weeks and two months after injection only in hearts transplanted with HUVEC. While no signs of transdifferentiation into cardiomyocytes were evident, staining for the rat macrophage marker ED-1, adjacent to or colocalized with BrdU(+) signals, revealed an in.ltration with macrophages and implied the phagocytosis of injected HUVEC. In the vicinity of BrdU(+) signals, the density of CD31(+) microvessels was significantly increased in HUVEC-transplanted as compared to medium-treated hearts after two months. HUVEC transplantation led to improved contractility as assessed by echocardiography and to higher coronary flow rates as well as to improved response to volume strain and catecholamine stress in Langendorff perfused hearts.

CONCLUSIONS

After MI, transplanted HUVEC persist in the host myocardium and trigger an infiltration with macrophages. The ensuing increase in neovascularization and improvement in global left ventricular function may be attributable to the associated inflammatory response.

A potential pro-angiogenic cell therapy with human placenta-derived mesenchymal cells

Recently several strategies to treat ischemic diseases have been proposed but the ideal way has to be determined. We explored whether human placenta-derived mesenchymal cells (hPDMCs) can be used for this purpose because placenta is very rich in vessels. First, production of human vascular endothelial growth factor (hVEGF) from hPDMCs was examined. The amount of hVEGF secreted by hPDMCs was similar to the amount produced by HeLa cells. hVEGF was barely detected in human umbilical vein endothelial cells (hUVECs) or human peripheral blood mononuclear cells. hVEGF secreted from hPDMCs stimulated the proliferation of hUVECs, indicating its biological activity. Transplantation of hPDMCs to the ischemic limbs of NOD/Shi-scid mice significantly improved the blood flow of the affected limbs. Blood vessel formation was more prominently observed in the limbs of treated mice as compared to the control mice. Real-time RT-PCR revealed that hPDMCs produced hVEGF for at least 7 days after transplantation. Thus, transplantation of hPDMCs could potentially be a promising treatment for human ischemic diseases.

A terapia celular no tratamento da isquemia crítica dos membros inferiores

Os autores fazem um histórico sobre as pesquisas com células-tronco embrionárias e do cordão umbilical, suas respectivas vantagens e desvantagens. Seguem com as discussões sobre células-tronco adultas, sua definição, histórico, fontes e participação nos processos de regeneração tecidual, particularmente no endotélio. Ressaltam a importância de fatores que mobilizam as células-tronco adultas a partir da medula óssea: citocinas, angiopoietinas e outros fatores de crescimento. As células-tronco adultas mobilizam-se sob a forma de células endoteliais progenitoras, que têm origem comum com as células endoteliais a partir dos hemangioblastos. Os fatores de mobilização manifestam-se em condições de hipoxia e fazem com que as células endoteliais progenitoras se localizem nos locais de isquemia para produzir a neovasculogênese, que se faz por três possíveis mecanismos: a angiogênese (formação de novos capilares a partir de brotos de capilares já existentes), a arteriogênese (relacionada à circulação colateral) e a vasculogênese (vasos realmente novos). Fazem, a seguir, uma análise da literatura relativa à experimentação animal e aos estudos clínicos. Concluem ressaltando que as células-tronco adultas, embora tenham um grande potencial de uso, ainda demandam muito estudo e pesquisa para se firmar como método terapêutico.

Granulocyte-Colony Stimulating Factor Augments Neovascularization Induced by Bone Marrow Transplantation in Rat Hindlimb Ischemia

Because granulocyte-colony stimulating factor (G-CSF) mobilizes bone marrow cells including endothelial progenitor cells, we examined whether G-CSF augments angiogenesis and collateral vessel formation induced by bone marrow-mononuclear cells transplantation (BMT). Unilateral hindlimb ischemia was surgically induced in Lewis rats. One week after surgery, administration of 100 mg/kg per day G-CSF significantly increased the laser Doppler blood perfusion index (LDBPI), number of angiographically detectable collateral vessels (angiographic score), and capillary density determined by alkaline phosphatase staining. In the BMT group (1 x 10(7) cells/rat) and the group with combined G-CSF treatment and BMT, LDBPI was significantly increased compared with that in the vehicle-treated group. In the BMT group, neovascularization was significantly increased as evidenced by the angiographic score and capillary density compared with the vehicle-treated group. Furthermore, the combination of G-CSF treatment and BMT augmented neovascularization compared with BMT alone, as evidenced by the angiographic score and capillary density. Moreover, G-CSF significantly increased vascular endothelial growth factor mRNA and fibroblast growth factor-2 mRNA in hindlimb muscle. In conclusion, G-CSF was found to augment neovascularization in rat hindlimb ischemia. Combined use of G-CSF treatment and BMT may be a useful strategy for therapeutic neovascularization in ischemic tissues.