We have previously demonstrated that implanted microvessels form a new microcirculation with minimal host-derived vessel investment. Our objective was to define the vascular phenotypes present during neovascularization in these implants and identify post-angiogenesis events. Morphological, functional and transcriptional assessments identified three distinct vascular phenotypes in the implants: sprouting angiogenesis, neovascular remodeling, and network maturation. A sprouting angiogenic phenotype appeared first, characterized by high proliferation and low mural cell coverage. This was followed by a neovascular remodeling phenotype characterized by a perfused, poorly organized neovascular network, reduced proliferation, and re-associated mural cells. The last phenotype included a vascular network organized into a stereotypical tree structure containing vessels with normal perivascular cell associations. In addition, proliferation was low and was restricted to the walls of larger microvessels. The transition from angiogenesis to neovascular remodeling coincided with the appearance of blood flow in the implant neovasculature. Analysis of vascularspecific and global gene expression indicates that the intermediate, neovascular remodeling phenotype is transcriptionally distinct from the other two phenotypes. Therefore, this vascular phenotype likely is not simply a transitional phenotype but a distinct vascular phenotype involving unique cellular and vascular processes. Furthermore, this neovascular remodeling phase may be a normal aspect of the general neovascularization process. Given that this phenotype is arguably dysfunctional, many of the microvasculatures present within compromised or diseased tissues may not represent a failure to progress appropriately through a normally occurring neovascularization phenotype.

To investigate the full range of molecular changes associated with erectile dysfunction (ED) in Type 1 diabetes, we examined alterations in penile gene expression in streptozotocin-induced diabetic rats and littermate controls. With the use of Affymetrix GeneChip arrays and statistical filtering, 529 genes/transcripts were considered to be differentially expressed in the diabetic rat cavernosum compared with control. Gene Ontology (GO) classification indicated that there was a decrease in numerous extracellular matrix genes (e.g., collagen and elastin related) and an increase in oxidative stress-associated genes in the diabetic rat cavernosum. In addition, PubMatrix literature mining identified differentially expressed genes previously shown to mediate vascular dysfunction [e.g., ceruloplasmin (Cp), lipoprotein lipase, and Cd36] as well as genes involved in the modulation of the smooth muscle phenotype (e.g., Kruppel-like factor 5 and chemokine C-X3-C motif ligand 1). Real-time PCR was used to confirm changes in expression for 23 relevant genes. Further validation of Cp expression in the diabetic rat cavernosum demonstrated increased mRNA levels of the secreted and anchored splice variants of Cp. CP protein levels showed a 1.9-fold increase in tissues from diabetic rats versus controls. Immunohistochemistry demonstrated localization of CP protein in cavernosal sinusoids of control and diabetic animals, including endothelial and smooth muscle layers. Overall, this study broadens the scope of candidate genes and pathways that may be relevant to the pathophysiology of diabetes-induced ED as well as highlights the potential complexity of this disorder.

Vascular compromise and the accompanying perfusion deficits cause or complicate a large array of disease conditions and treatment failures. This has prompted the exploration of therapeutic strategies to repair or regenerate vasculatures thereby establishing more competent microcirculatory beds. Growing evidence indicates that an increase in vessel numbers within a tissue does not necessarily promote an increase in tissue perfusion. Effective regeneration of a microcirculation entails the integration of new stable microvessel segments into the network via neovascularization. Beginning with angiogenesis, neovascularization entails an integrated series of vascular activities leading to the formation of a new mature microcirculation and includes vascular guidance and inosculation, vessel maturation, pruning, arterio-venous specification, network patterning, structural adaptation, intussusception, and microvascular stabilization. While the generation of new vessel segments is necessary to expand a network, without the concomitant neovessel remodeling and adaptation processes intrinsic to microvascular network formation, these additional vessel segments give rise to a dysfunctional microcirculation. While many of the mechanisms regulating angiogenesis have been detailed, a thorough understanding of the mechanisms driving post-angiogenesis activities specific to neovascularization has yet to be fully realized, but is necessary in order to develop effective therapeutic strategies for repairing compromised microcirculations as a means to treat disease.

Objective-Fibroblast growth factor-2 (FGF2) has been implicated as a mediator in the structural remodeling of arteries.Chronic changes in blood flow are known to cause reorganization of the vessel wall, resulting in permanent changes in artery size (flow-dependent remodeling). Using FGF2 knockout (Fgf2 Ϫ/Ϫ ) mice, we tested the hypothesis that FGF2 is required during flow-dependent remodeling of the carotid arteries. Methods and Results-All branches originating from the left common carotid artery (LCCA), except for the left thyroid artery, were ligated to reduce flow in the LCCA and increase flow in the contralateral right common carotid artery (RCCA Key Words: arterial remodeling Ⅲ basic fibroblast growth factor Ⅲ knockout mice Ⅲ flow-dependent remodeling Ⅲ fibroblast growth factor-2 V ascular remodeling is the structural reorganization of a vessel involving a variety of cell activities, including proliferation, apoptosis, migration, and extracellular matrix restructuring. 1-3 Remodeling of the arterial wall occurs after chronic changes in blood pressure and blood flow and in response to vessel injury. 4 -7 Arterial remodeling due to changes in blood flow (flow-dependent remodeling) occurs in physiological 1,8 and pathological situations. 9 -12 In pathological settings, such as atherosclerosis and angioplasty, arterial remodeling plays a critical role in the degree of vessel narrowing during plaque or lesion progression. 5,[13][14][15][16] The molecular mediators of vessel remodeling are still unclear. Fibroblast growth factor-2 (FGF2) is a molecule that is strongly implicated in flow-dependent remodeling. FGF2 mRNA expression is sensitive to alterations in fluid flow and shear stress, 17 and FGF2 protein expression increases in the vascular wall during flow-induced arterial enlargement. 18 In addition, antibody neutralization of endogenous FGF2 has been shown to reduce inward remodeling in a mouse model of carotid artery flow cessation. 19 The specific function of FGF2 during these remodeling events is not clear. Previous studies suggest that FGF2 could possibly be affecting vascular cell turnover, gene expression, or matrix restructuring in the adapting vessel. 20 -25 We used a novel mouse model of vessel remodeling, with FGF2 knockout (Fgf2 Ϫ/Ϫ ) mice, to test the hypothesis that FGF2 is required during flow-dependent arterial remodeling. The model induces inward (low flow-induced) and outward (high flow-induced) remodeling in the left and right carotid arteries, respectively. MethodsAn expanded Methods section is available online at http://atvb.ahajournals.org. Experimental AnimalsMale FGF2 wild-type (Fgf2 ϩ/ϩ ) and Fgf2 Ϫ/Ϫ mice 26 (50% Black Swiss and 50% 129 SV) were used for all experiments in accordance with University of Arizona Institutional Animal Care and Useapproved procedures. All mice were genotyped by polymerase chain reaction by using primers specific for the FGF2 wild-type and knockout alleles, after collection of genomic DNA. Procedures were timed so that all mice were 8 weeks of age (Ϯ...