Tissue Revascularization Research Articles

Resolvin D2 Enhances Postischemic Revascularization While Resolving Inflammation.

Resolvins are lipid mediators generated by leukocytes during the resolution phase of inflammation. They have been shown to regulate the transition from inflammation to tissue repair; however, it is unknown whether resolvins play a role in tissue revascularization following ischemia. We used a murine model of hind limb ischemia (HLI), coupled with laser Doppler perfusion imaging, microcomputed tomography, and targeted mass spectrometry, to assess the role of resolvins in revascularization and inflammation resolution. In mice undergoing HLI, we identified resolvin D2 (RvD2) in bone marrow and skeletal muscle by mass spectrometry (n=4-7 per group). We also identified RvD2 in skeletal muscle biopsies from humans with peripheral artery disease. Monocytes were recruited to skeletal muscle during HLI and isolated monocytes produced RvD2 in a lipoxygenase-dependent manner. Exogenous RvD2 enhanced perfusion recovery in HLI and microcomputed tomography of limb vasculature revealed greater volume, with evidence of tortuous arterioles indicative of arteriogenesis (n=6-8 per group). Unlike other treatment strategies for therapeutic revascularization that exacerbate inflammation, RvD2 did not increase vascular permeability, but reduced neutrophil accumulation and the plasma levels of tumor necrosis factor-α and granulocyte macrophage colony-stimulating factor. In mice treated with RvD2, histopathologic analysis of skeletal muscle of ischemic limbs showed more regenerating myocytes with centrally located nuclei. RvD2 enhanced endothelial cell migration in a Rac-dependent manner, via its receptor, GPR18, and Gpr18-deficient mice had an endogenous defect in perfusion recovery following HLI. Importantly, RvD2 rescued defective revascularization in diabetic mice. RvD2 stimulates arteriogenic revascularization during HLI, suggesting that resolvins may be a novel class of mediators that both resolve inflammation and promote arteriogenesis.

Abstract 31: First Trimester Human Umbilical Cord Perivascular Cells (FTM HUCPVCs) Show Superior Angiogenic Potential in Angiogenic Potency Assays When Compared to Term HUCPVCs and Bone Marrow Stromal Cells

Introduction: Cell therapy employing pro-angiogenic cell types is a promising option for promoting revascularization of ischemic tissues. First trimester human umbilical cord perivascular cells (FTM HUCPVCs) are a young source of mesenchymal stromal cells (MSCs) that support blood vessels in the umbilical cord. Objective: We aimed to determine the angiogenic potential of FTM HUCPVCs using angiogenic potency assays and compare to older sources of MSCs: term HUCPVCs and bone marrow stromal cells (BMSCs). Methods: For the aortic ring assay, aortas were sectioned and embedded into Matrigel™. Fluorophore-labeled MSCs for testing were added to developing endothelial networks (Day0). MSC integration and network development were monitored by microscopy and quantification of endothelial networks was performed using ImageJ™ software (Day4) n=3. Using the Matrigel™ plug assay, 5.0 x10 5 MSCs were suspended with equal volumes of Matrigel™ and injected subcutaneously in 11-week-old nude mice and isolated after two weeks. Plug associated microvasculature was imaged and quantified n=3. Results: In the aortic ring assay, FTM HUCPVCs homed to endothelial networks and demonstrated greater endothelial cell coverage, when compared to term HUCPVCs and BMSCs. FTM HUCPVCs showed significantly greater network growth when compared to term HUCPVCs ( p ≤0.001), BMSCs ( p ≤0.001) and untreated endothelial networks ( p ≤0.001). FTM HUCPVC contributed to a significantly greater number of closed loops when compared to term HUCPVCs ( p ≤0.01), BMSCs ( p ≤0.001) and untreated networks ( p ≤0.05). At two weeks following injection of Matrigel plugs, FTM HUCPVC resulted in significantly greater blood vessel recruitment when compared to term HUCPVCs ( p ≤0.05), BMSCs ( p ≤0.01) and control media plugs ( p ≤0.01). Small tortuous blood vessels were found in significantly higher quantity in FTM HUCPVC injected plugs when compared to term HUCPVCs ( p ≤0.05), BMSCs (p ≤0.01) and media plugs ( p ≤0.001). Conclusions: These studies demonstrate that FTM HUCPVCs have superior potential to augment, both the initiation of capillary formation and the development of functional, perfusable blood vessels, highlighting their potential for tissue regeneration following ischemic injury.

Oxygénothérapie hyperbare et radiothérapie : entre mythe et réalité

Worldwide, more than a million people receive each year a curative radiotherapy. While local control and overall survival are steadily increasing, 5 to 15% of patients still develop above grade 2 late toxicities. Late toxicities treatments are complex. Hyperbaric oxygenation was shown to induce revascularization and healing of injured tissues, but indications are still debated. Through a literature review, we summarized the hyperbaric oxygenation indications in radiation-induced late toxicities. We also studied the knowledge and practice of French local radiation therapists. It seems that hyperbaric oxygen therapy can be a conservative treatment of haemorrhagic cystitis and radiation-induced pain, in case of drug therapies failure. Often associated with a significant morbidity and mortality, surgery could be avoided. The risk of complications in case of tooth extraction in irradiated tissues is also reduced. However, the role of hyperbaric oxygenation for mandibular osteoradionecrosis, radiation-induced proctitis, enteritis, lymphoedema, brachial plexopathy, skin and neurological sequelae seems more questionable since studies results are conflicting. Future outcomes of phase III studies are expected to clarify the role of hyperbaric oxygenation in the management of radio-induced toxicities, including for head and necks complications.

Therapeutic assessment of mesenchymal stem cells delivered within a PEGylated fibrin gel following an ischemic injury.

The intent of the current study was to investigate the therapeutic contribution of MSCs to vascular regeneration and functional recovery of ischemic tissue. We used a rodent hind limb ischemia model and intramuscularly delivered MSCs within a PEGylated fibrin gel matrix. Within this model, we demonstrated that MSC therapy, when delivered in PEGylated fibrin, results in significantly higher mature blood vessel formation, which allows for greater functional recovery of skeletal muscle tissue as assessed using force production measurements. We observed initial signs of vascular repair at early time points when MSCs were delivered without PEGylated fibrin, but this did not persist or lead to recovery of the tissue in the long-term. Furthermore, animals which were treated with PEGylated fibrin alone exhibited a greater number of mature blood vessels, but they did not arterialize and did not show improvements in force production. These results demonstrate that revascularization of ischemic tissue may be a necessary but not sufficient step to complete functional repair of the injured tissue. This work has implications on stem cell therapies for ischemic diseases and also potentially on how such therapies are evaluated.

Penetrating pelvic trauma: Initial assessment and surgical management in emergency

Penetrating pelvic trauma (PPT) is defined as a wound extending within the bony confines of the pelvis to involve the vascular, intestinal or urinary pelvic organs. The gravity of PPT is related to initial hemorrhage and the high risk of late infection. If the patient is hemodynamically unstable and in hemorrhagic shock, the urgent treatment goal is rapid achievement of hemostasis. Initial strategy relies on insertion of an intra-aortic occlusion balloon and/or extraperitoneal pelvic packing, performed while damage control resuscitation is ongoing before proceeding to arteriography. If hemodynamic instability persists, a laparotomy for hemostasis is performed without delay. In a hemodynamically stable patient, contrast-enhanced CT is systematically performed to obtain a comprehensive assessment of the lesions prior to surgery. At surgery, damage control principles should be applied to all involved systems (digestive, vascular, urinary and bone), with exteriorization of digestive and urinary channels, arterial revascularization, and wide drainage of peri-rectal and pelvic soft tissues. When immediate definitive surgery is performed, management must address the frequent associated lesions in order to reduce the risk of postoperative sepsis and fistula.

Design, fabrication and perivascular implantation of bioactive scaffolds engineered with human adventitial progenitor cells for stimulation of arteriogenesis in peripheral ischemia

Cell therapy represents a promising option for revascularization of ischemic tissues. However, injection of dispersed cells is not optimal to ensure precise homing into the recipient’s vasculature. Implantation of cell-engineered scaffolds around the occluded artery may obviate these limitations. Here, we employed the synthetic polymer polycaprolactone for fabrication of 3D woodpile- or channel-shaped scaffolds by a computer-assisted writing system (pressure assisted micro-syringe square), followed by deposition of gelatin (GL) nanofibers by electro-spinning. Scaffolds were then cross-linked with natural (genipin, GP) or synthetic (3-glycidyloxy-propyl-trimethoxy-silane, GPTMS) agents to improve mechanical properties and durability in vivo. The composite scaffolds were next fixed by crown inserts in each well of a multi-well plate and seeded with adventitial progenitor cells (APCs, 3 cell lines in duplicate), which were isolated/expanded from human saphenous vein surgical leftovers. Cell density, alignment, proliferation and viability were assessed 1 week later. Data from in vitro assays showed channel-shaped/GPTMS-crosslinked scaffolds confer APCs with best alignment and survival/growth characteristics. Based on these results, channel-shaped/GPTMS-crosslinked scaffolds with or without APCs were implanted around the femoral artery of mice with unilateral limb ischemia. Perivascular implantation of scaffolds accelerated limb blood flow recovery, as assessed by laser Doppler or fluorescent microspheres, and increased arterial collaterals around the femoral artery and in limb muscles compared with non-implanted controls. Blood flow recovery and perivascular arteriogenesis were additionally incremented by APC-engineered scaffolds. In conclusion, perivascular application of human APC-engineered scaffolds may represent a novel option for targeted delivery of therapeutic cells in patients with critical limb ischemia.

LRP in Endothelial Cells

Endothelial cells are highly heterogeneous1 and participate in angiogenesis, an integrated set of responses in which new blood vessels are formed from existing ones. During angiogenesis, endothelial cells exhibit increased migration and proliferation2 and contribute to the reorganization of the extracellular matrix. Angiogenesis occurs during embryonic development and is also initiated during wound healing and pathological conditions, such as ischemia. Although most often the revascularization of ischemic tissues is highly beneficial, under certain conditions, it can be harmful. For example, pathological angiogenesis in the retina during diabetic retinopathy can result in blindness.3 Several molecules influence angiogenesis, including vascular endothelial growth factor,4 Notch,5 and Wnt.6 In this edition of Atherosclerosis, Thrombosis, and Vascular Biology , Mao et al7 identify another key player in this process: the low-density lipoprotein receptor–related protein 1 (LRP1) by demonstrating a significant role for LRP1 in orchestrating angiogenesis during retinal neovascularization. See accompanying article on page 350 LRP1, is a highly efficient endocytic as well as a signal transducing receptor that binds multiple ligands,8–11 and modulates signaling pathways by regulating the extracellular levels of growth factors and binding adaptor molecules to its intracellular domain (ICD). LRP1 plays an important role in the development12,13 and maintenance of the vasculature.14,15 Deletion of the Lrp1 gene in mice results in early embryonic lethality12 because of extensive hemorrhaging occurring around E13.5.13 The underlying vascular defect results from a failure to recruit and maintain vascular smooth muscle cells and pericytes of vessels resulting in extreme dilation of the aorta with a thin and disorganized smooth muscle cell layer and discontinuity of the vascular endothelium. Interestingly, the phenotype observed for Lrp1 −/− embryos resembles that of mice genetically deficient in sphingosine-1-phosphate receptor S1PR1. Like the …

Chest Wall Reconstruction: Evolution Over a Decade and Experience With a Novel Technique for Complex Defects.

Chest wall reconstruction (CWR) with biologic matrices has gained popularity over the last decade; however, data on this topic remain sparse. The aim of this study is to review the different methods and materials used for CWR while reviewing and highlighting a novel approach using a biologic inlay and synthetic onlay technique for larger, complex high-risk defects. A retrospective review was performed of all patients who underwent full thickness chest wall resection and reconstruction during a 10-year period. Patient characteristics, comorbidities, operative data, as well as postoperative wound complications and outcomes were reviewed. Different reconstructive methods and materials were reviewed and compared. From December 2003 to January 2014, a total of 81 patients underwent CWR. The indications for resection/reconstruction included oncologic in 49 patients (60.5%), desmoids tumors in 10 (12.3%), bronchopleural fistula in 3 (3.7%), infection in 7 (8.6%), and anatomic deformity in 7 (8.6%) patients. Synthetic and/or acellular dermal matrices (ADM) reconstruction was used in 59 patients (10 biologic, 22 synthetic, and 27 biologic ADM inlay/synthetic onlay combination). On average, 2.5, 3.5, and 3.6 ribs were resected in the biologic, synthetic, and combination group, respectively (P = 0.1). A greater number of patients in the combination group had a history of chemotherapy and/or radiation therapy (P = 0.03) than the synthetic or biologic alone groups. Risk analysis demonstrated an association between the number of ribs resected and postoperative chest wall complications. The incidence of chest wall/wound complications in the synthetic, combination, and biologic groups was 31.8%, 22.2%, and 10%, respectively (P = 0.47). In the largest single institution study comparing the use of different reconstructive materials, including ADM in CWR, the authors demonstrate that a biologic inlay/synthetic onlay may be used effectively for high-risk, large complex defects. Early outcomes with this technique are promising. The authors believe this combination highlights benefits from both materials because the ADM facilitates tissue ingrowth and revascularization, whereas the synthetic component provides structural durability. Additional studies with larger sample sizes are necessary to further explore the benefits of the combination technique to determine if outcomes are better than either material alone when used to reconstruct high-risk wounds after larger resections.

Apoptosis, proliferation, and morphology during vein graft remodeling in rabbits.

Neo-intima development and atherosclerosis limit the long-term use of vein grafts for revascularization of ischemic tissues. Recently, studies have confirmed that proliferating cell nuclear antigen (PCNA) plays an important role in cell proliferation. Our research confirmed that 28 days after vein transplantation, PCNA expression increases significantly. Using rabbits, rather than rodents, for a more representative model of human vein grafts, we aimed to establish a time course of changes in cell proliferation and apoptosis using morphometric and immunohistochemical analyses, western blot, terminal deoxynucleotidyl transferase dUTP nick end labeling, and transmission electron microscopy (TEM). The external jugular veins of 42 healthy purebred male New Zealand white rabbits were grafted onto their common carotid arteries. The rabbits were divided into seven groups, with vein grafts being harvested before surgery, and at 1, 3, 7, 14, 28, and 90 days afterwards. The extent of stenosis and apoptosis, PCNA protein levels, and TEM morphology were subsequently examined. Intimal thickness was slightly decreased 1 day following surgery, but then increased continuously until the 90th day. Western blot and immunohistochemistry both indicated lowered PCNA expression on day 1, although levels subsequently increased, peaking at 7 days post-surgery. After surgery, apoptosis was lowest on day 7, and remained low thereafter. TEM revealed signs of apoptosis as vein graft restenosis progressed. Proliferation and apoptosis co-occurred following grafting, indicating that both processes were involved in vein graft remodeling. Apoptosis levels were highest between days 1 and 3 after surgery, whereas proliferation culminated on the 7th day.

Utilization of Novel Delivery Drug Systems Based on Release of Extracellular Vesicles in Heart Failure

Heart failure (HF) remains to be a serious public and health problem, which associate with higher morbidity, mortality and disability. Although there are high-quality developed clinical recommendations regarding prevention and treatment of HF, patients with HF have experienced the poor clinical outcomes. Currently transfer of drugs using extracellular vesicles (EVs) into target cells in vivo is promising methods for attenuation of cardiac remodeling and ischemia. The mini review is presented data confirming the role of specific novel delivery drug systems released wide spectrum of biological active molecules based on EVs’ releasing in HF. The use of EV systems might allow localized and sustained cytokine release and consequently a prolonged biological effect with induction of tissue regeneration and revascularization in HF.

Adipose-derived stem cell conditioned medium (ASC-CM) promotes revascularization of ischemic tissues in a rabbit model of peripheral artery disease

Adipose-derived stem cell conditioned medium (ASC-CM) promotes revascularization of ischemic tissues in a rabbit model of peripheral artery disease

Nrf2 in ischemic neurons promotes retinal vascular regeneration through regulation of semaphorin 6A

Delayed revascularization of ischemic neural tissue is a major impediment to preservation of function in central nervous system (CNS) diseases including stroke and ischemic retinopathies. Therapeutic strategies allowing rapid revascularization are greatly needed to reduce ischemia-induced cellular damage and suppress harmful pathologic neovascularization. However, key mechanisms governing vascular recovery in ischemic CNS, including regulatory molecules governing the transition from tissue injury to tissue repair, are largely unknown. NF-E2-related factor 2 (Nrf2) is a major stress-response transcription factor well known for its cell-intrinsic cytoprotective function. However, its role in cell-cell crosstalk is less appreciated. Here we report that Nrf2 is highly activated in ischemic retina and promotes revascularization by modulating neurons in their paracrine regulation of endothelial cells. Global Nrf2 deficiency strongly suppresses retinal revascularization and increases pathologic neovascularization in a mouse model of ischemic retinopathy. Conditional knockout studies demonstrate a major role for neuronal Nrf2 in vascular regrowth into avascular retina. Deletion of neuronal Nrf2 results in semaphorin 6A (Sema6A) induction in hypoxic/ischemic retinal ganglion cells in a hypoxia-inducible factor-1 alpha (HIF-1α)-dependent fashion. Sema6A expression increases in avascular inner retina and colocalizes with Nrf2 in human fetal eyes. Extracellular Sema6A leads to dose-dependent suppression of the migratory phenotype of endothelial cells through activation of Notch signaling. Lentiviral-mediated delivery of Sema6A small hairpin RNA (shRNA) abrogates the defective retinal revascularization in Nrf2-deficient mice. Importantly, pharmacologic Nrf2 activation promotes reparative angiogenesis and suppresses pathologic neovascularization. Our findings reveal a unique function of Nrf2 in reprogramming ischemic tissue toward neurovascular repair via Sema6A regulation, providing a potential therapeutic strategy for ischemic retinal and CNS diseases.

Endothelial sprouting and network formation in collagen- and fibrin-based modular microbeads

A modular tissue engineering approach may have advantages over current therapies in providing rapid and sustained revascularization of ischemic tissue. In this study, modular protein microbeads were prepared from pure fibrin (FIB) and collagen–fibrin composites (COL–FIB) using a simple water-in-oil emulsification technique. Human endothelial cells and fibroblasts were embedded directly in the microbead matrix. The resulting microbeads were generally spheroidal with a diameter of 100–200μm. Cell viability was high (75–80% viable) in microbeads, but was marginally lower than in bulk hydrogels of corresponding composition (85–90% viable). Cell proliferation was significantly greater in COL–FIB microbeads after two weeks in culture, compared to pure FIB microbeads. Upon embedding of microbeads in a surrounding fibrin hydrogel, endothelial cell networks formed inside the microbead matrix and extended into the surrounding matrix. The number of vessel segments, average segment length, and number of branch points was higher in FIB samples, compared to COL–FIB samples, resulting in significantly longer total vessel networks. Anastomosis of vessel networks from adjacent microbeads was also observed. These studies demonstrate that primitive vessel networks can be formed by modular protein microbeads containing embedded endothelial cells and fibroblasts. Such microbeads may find utility as prevascularized tissue modules that can be delivered minimally invasively as a therapy to restore blood flow to ischemic tissues. Statement of significanceVascularization is critically important for tissue engineering and regenerative medicine, and materials that support and/or promote neovascularization are of value both for translational applications and for mechanistic studies and discovery-based research. Therefore, we fabricated small modular microbeads formulated from pure fibrin (FIB) and collagen–fibrin (COL–FIB) containing endothelial cells and supportive fibroblasts. We explored how cells encapsulated within these materials form microvessel-like networks both within and outside of the microbeads when embedded in larger 3D matrices. FIB microbeads were found to initiate more extensive sprouting into the surrounding ECM in vitro. These results represent an important step towards our goal of developing injectable biomaterial modules containing preformed vascular units that can rapidly restore vascularization to an ischemic tissue in vivo.

Therapeutic manipulation of angiogenesis with miR-27b.

BackgroundMultiple studies demonstrated pro-angiogenic effects of microRNA (miR)-27b. Its targets include Notch ligand Dll4, Sprouty (Spry)-2, PPARγ and Semaphorin (SEMA) 6A. miR-27 effects in the heart are context-dependent: although it is necessary for ventricular maturation, targeted overexpression in cardiomyocytes causes hypertrophy and dysfunction during development. Despite significant recent advances, therapeutic potential of miR-27b in cardiovascular disease and its effects in adult heart remain unexplored. Here, we assessed the therapeutic potential of miR-27b mimics and inhibitors in rodent models of ischemic disease and cancer.MethodsWe have used a number of models to demonstrate the effects of miR-27b mimicry and inhibition in vivo, including subcutaneous Matrigel plug assay, mouse models of hind limb ischemia and myocardial infarction and subcutaneous Lewis Lung carcinoma.ResultsUsing mouse model of myocardial infarction due to the coronary artery ligation, we showed that miR-27b mimic had overall beneficial effects, including increased vascularization, decreased fibrosis and increased ejection fraction. In mouse model of critical limb ischemia, miR-27b mimic also improved tissue re-vascularization and perfusion. In both models, miR-27b mimic clearly decreased macrophage recruitment to the site of hypoxic injury. In contrast, miR-27b increased the recruitment of bone marrow derived cells to the neovasculature, as was shown using mice reconstituted with fluorescence-tagged bone marrow. These effects were due, at least in part, to the decreased expression of Dll4, PPARγ and IL10. In contrast, blocking miR-27b significantly decreased vascularization and reduced growth of subcutaneous tumors and decreased BMDCs recruitment to the tumor vasculature.ConclusionsOur study demonstrates the utility of manipulating miR-27b levels in the treatment of cardiovascular disease and cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/s13221-015-0031-1) contains supplementary material, which is available to authorized users.

Tideglusib, an allosteric inhibitor of Glycogen Synthase Kinase (GSK)‐3β increases Angiogenic activities of Endothelial Cells

RationaleThe regulation of blood vessel growth is of paramount importance in ischemic cardiovascular and peripheral limb diseases. However, there is no effective pharmacotherapy to induce rapid revascularization of ischemic tissues.GoalTo address if newly discovered allosteric inhibitor of GSK‐3β enzyme, Tideglusib (TDG) regulates angiogenic phenotypes of endothelial cells.Methods and ResultsThe treatment of cultured ECs with Wnt3a or TDG stabilized β‐catenin polypeptide species in a time dependent manner. Quantitative RT‐PCR showed increased Cyclin‐D1, Nanog, c‐myc and Vascular Endothelial Growth Factor Receptor‐2(VEGFR‐2) transcripts. Accordingly, TDG increased expression of not only transcription factor Nanog, but also Cyclin‐D1 and VEGFR‐2 proteins. Microscopic analyses of ECs stained with anti‐VE‐cadherin antibody provided evidence of the disappearance of VE‐cadherin from the adherens junctions, while increased accumulation of β‐catenin in the nucleus. Pretreatment of ECs with TDG followed by Propidium iodide (PI) and Annexin‐V labeling showed increased survival and decreased cell death (p<0.05). Importantly, TDG treatment and the addition of 5‐bromo‐2′‐deoxyuridine (BrdU) followed by microscopy showed significant increase in the incorporation of BrdU in ECs. In addition, in a scratch assay and Boyden‐chamber cell migration experiments indicated the ability of TDG to induce migration of ECs. Furthermore, in an aortic ring assay TDG increased angiogenesis significantly.SummaryThus, for the first time, we show that TDG up‐regulates expression of Nanog, Cyclin‐D1 and VEGFR‐2 to augment neovessel formation, a critical biological process required for re‐establishing blood flow to the ischemic tissues.

Influence of mouse strain on ovarian tissue recovery after engraftment with angiogenic factor.

BackgroundFor women facing gonadotoxic treatment, cryopreservation of ovarian tissue with subsequent retransplantation during remission is a promising technique for fertility preservation. However, follicle loss within grafted ovarian tissue can be caused by ischemia and progressive revascularization. Several xenograft models using different immunodeficient rodent lines are suitable for studying ovarian tissue survival and follicular viability after frozen-thawed ovarian cortex transplantation. SCID mice, which are deficient for functional B and T cells, are the most commonly used mice for ovarian xenograft studies. However, due to incomplete immunosuppression, NOD-SCID mice displaying low NK cell function and an absence of circulating complement might be more appropriate. The present study aims to define the most appropriate immunodeficient mouse strain for ovarian tissue xenotransplantation by comparing ovarian graft recovery in SCID and NOD-SCID mice following engraftment in the presence of isoform 111 of vascular endothelial growth factor.MethodsSheep ovarian cortex fragments were embedded in a collagen matrix, with or without VEGF111, before being stitched onto the ovaries of SCID and NOD-SCID mice. Transplants were recovered after 3 days to study early revascularization or after 3 weeks to evaluate follicle preservation and tissue fibrosis through histological analyses.ResultsAt day 3, vessels were largely reorganized in the ovarian grafts of both mouse strains. After 3 weeks, the cortical tissue was clearly identifiable in SCID mice but not in NOD-SCID mice. Upon VEGF111 treatment, vascularization was significantly improved 3 days after transplantation in SCID mice. This increase in vessel density was correlated with better follicular preservation in SCID mice 3 weeks after transplantation. Fibrosis was not decreased by VEGF treatment in either mouse strain.ConclusionsTissue architecture and follicular morphology were better preserved in ovarian tissues grafted in SCID mice in comparison with NOD-SCID mice. Moreover, tissue revascularization was improved in SCID mice by VEGF111 graft treatment. Thus, we consider SCID mice to be the best murine model for studying ovarian tissue xenografts.

Resolution of liver fibrosis requires myeloid cell-driven sinusoidal angiogenesis.

Angiogenesis is a key feature of liver fibrosis. Although sinusoidal remodeling is believed to contribute to fibrogenesis, the impact of sinusoidal angiogenesis on the resolution of liver fibrosis remains undefined. Myeloid cells, particularly macrophages, constantly infiltrate the fibrotic liver and can profoundly contribute to remodeling of liver sinusoids. We observe that the development of fibrosis is associated with decreased hepatic vascular endothelial growth factor (VEGF) expression as well as sinusoidal rarefication of the fibrotic scar. In contrast, the resolution of fibrosis is characterized by a rise in hepatic VEGF levels and revascularization of the fibrotic tissue. Genetic ablation of VEGF in myeloid cells or pharmacological inhibition of VEGF receptor 2 signaling prevents this angiogenic response and the resolution of liver fibrosis. We observe increased expression of matrix metalloproteases as well as decreased expression of tissue inhibitor of metalloproteases confined to sinusoidal endothelial cells in response to myeloid cell VEGF. Remarkably, reintroduction of myeloid cell-derived VEGF upon recovery restores collagenolytic acitivity and the resolution of fibrosis. We identify myeloid cell-derived VEGF as a critical regulator of extracellular matrix degradation by liver endothelial cells, thereby unmasking an unanticipated link between angiogenesis and the resolution of fibrosis.

Effects of Erythropoietin on Adipose Tissue

Background: The increased resorption and the difficulty of the fat graft take following autologous fat transplantation procedure are associated with reduced fat tissue revascularization and increased apoptosis of adipose cells. We suppose that the lipofilling procedure induces an inflammatory environment within the fat graft mass, whose evolution influences the efficacy of autologous fat graft survival. Erythropoietin (EPO) is a glycoprotein hormone known to exert angiogenetic and anti-inflammatory effects; therefore, our purpose was to investigate its reaction with adipose tissue used in lipofilling. Methods: Fat masses were harvested using manual suction lipectomy and then seeded on dishes in appropriate culture and treated for 3 weeks with 3 doses of EPO. CD31 and CD68 immunohistochemistry was used to identify microvessels and several infiltrating leukocyte cells. Results: Following EPO administration, we have detected an increase in the number of CD31-positive microvessel endothelium cells and CD31-positive small leukocytes and a reduction of CD68-positive cells. These effects were more conspicuous following higher EPO dose. Conclusions: Our findings evidence EPO treatment as a useful strategy to sustain the revascularization of grafted tissue and to reduce its inflammatory state.

Effects of erythropoietin on adipose tissue: a possible strategy in refilling.

Background:The increased resorption and the difficulty of the fat graft take following autologous fat transplantation procedure are associated with reduced fat tissue revascularization and increased apoptosis of adipose cells. We suppose that the lipofilling procedure induces an inflammatory environment within the fat graft mass, whose evolution influences the efficacy of autologous fat graft survival. Erythropoietin (EPO) is a glycoprotein hormone known to exert angiogenetic and anti-inflammatory effects; therefore, our purpose was to investigate its reaction with adipose tissue used in lipofilling.Methods:Fat masses were harvested using manual suction lipectomy and then seeded on dishes in appropriate culture and treated for 3 weeks with 3 doses of EPO. CD31 and CD68 immunohistochemistry was used to identify microvessels and several infiltrating leukocyte cells.Results:Following EPO administration, we have detected an increase in the number of CD31-positive microvessel endothelium cells and CD31-positive small leukocytes and a reduction of CD68-positive cells. These effects were more conspicuous following higher EPO dose.Conclusions:Our findings evidence EPO treatment as a useful strategy to sustain the revascularization of grafted tissue and to reduce its inflammatory state.

Cell-sheet Therapy With Omentopexy Promotes Arteriogenesis and Improves Coronary Circulation Physiology in Failing Heart

Cell-sheet transplantation induces angiogenesis for chronic myocardial infarction (MI), though insufficient capillary maturation and paucity of arteriogenesis may limit its therapeutic effects. Omentum has been used clinically to promote revascularization and healing of ischemic tissues. We hypothesized that cell-sheet transplantation covered with an omentum-flap would effectively establish mature blood vessels and improve coronary microcirculation physiology, enhancing the therapeutic effects of cell-sheet therapy. Rats were divided into four groups after coronary ligation; skeletal myoblast cell-sheet plus omentum-flap (combined), cell-sheet only, omentum-flap only, and sham operation. At 4 weeks after the treatment, the combined group showed attenuated cardiac hypertrophy and fibrosis, and a greater amount of functionally (CD31(+)/lectin(+)) and structurally (CD31(+)/α-SMA(+)) mature blood vessels, along with myocardial upregulation of relevant genes. Synchrotron-based microangiography revealed that the combined procedure increased vascularization in resistance arterial vessels with better dilatory responses to endothelium-dependent agents. Serial (13)N-ammonia PET showed better global coronary flow reserve in the combined group, mainly attributed to improvement in the basal left ventricle. Consequently, the combined group had sustained improvements in cardiac function parameters and better functional capacity. Cell-sheet transplantation with an omentum-flap better promoted arteriogenesis and improved coronary microcirculation physiology in ischemic myocardium, leading to potent functional recovery in the failing heart.