Cardiovascular Innovation Institute

Louisville, KY, United States

Cardiovascular Innovation Institute

Louisville, KY, United States
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Leblanc A.J.,Cardiovascular Innovation Institute | Leblanc A.J.,Gynecology and Womens Health | Nguyen Q.T.,Cardiovascular Innovation Institute | Touroo J.S.,Cardiovascular Innovation Institute | And 5 more authors.
Stem Cells Translational Medicine | Year: 2013

We have previously shown that myocardial infarction (MI) immediately treated with an epicardial construct containing stromal vascular fraction (SVF) from adipose tissue preserved microvascular function and left ventricle contractile mechanisms. In order to evaluate a more clinically relevant condition, we investigated the cardiac recovery potential of an SVF construct implanted onto an established infarct. SVF cells were isolated from rat adipose tissue, plated on Vicryl, and cultured for 14 days. Fischer-344 rats were separated into MI groups: (a) 6-week MI (MI), (b) 6-week MI treated with an SVF construct at 2 weeks (MI SVF), (c) 6-week MI with Vicryl construct at 2 weeks (MI Vicryl), and (d) MI 2wk (time point of intervention). Emax, an indicator of systolic performance and contractile function, was lower in the MI and MI Vicryl versus MI SVF. Positron emission tomography imaging (18F-fluorodeoxyglucose) revealed a decreased percentage of relative infarct volume in the MI SVF versus MI and MI Vicryl. Total vessel count and percentage of perfusion assessed via immunohistochemistry were both increased in the infarct region of MI SVF versus MI and MI Vicryl. Overall cardiac function, percentage of relative infarct, and percentage of perfusion were similar between MI SVF and MI 2wk; however, total vessel count increased after SVF treatment. These data suggest that SVF treatment of an established infarct stabilizes the heart at the time point of intervention by preventing a worsening of cardiac performance and infarcted volume, and is associated with increased microvessel perfusion in the area of established infarct. © AlphaMed Press 2013.

Bernas M.J.,University of Arizona | Cardoso F.L.,University of Lisbon | Daley S.K.,University of Arizona | Weinand M.E.,University of Arizona | And 8 more authors.
Nature Protocols | Year: 2010

We describe a method for generating primary cultures of human brain microvascular endothelial cells (HBMVECs). HBMVECs are derived from microvessels isolated from temporal tissue removed during operative treatment of epilepsy. The tissue is mechanically fragmented and size filtered using polyester meshes. The resulting microvessel fragments are placed onto type I collagen-coated flasks to allow HBMVECs to migrate and proliferate. The overall process takes less than 3 h and does not require specialized equipment or enzymatic processes. HBMVECs are typically cultured for approximately 1 month until confluent. Cultures are highly pure (97% endothelial cells; 3% pericytes), are reproducible, and show characteristic brain endothelial markers (von Willebrand factor, glucose transporter-1) and robust expression of tight and adherens junction proteins as well as caveolin-1 and efflux protein P-glycoprotein. Monolayers of HBMVECs show characteristically high transendothelial electric resistance and have proven useful in multiple functional studies for in vitro modeling of the human blood-brain barrier. © 2010 Nature America, Inc. All rights reserved.

Kondo K.,Emory University | Bhushan S.,Emory University | King A.L.,Emory University | Prabhu S.D.,University of Alabama at Birmingham | And 10 more authors.
Circulation | Year: 2013

Background-: Cystathionine γ-lyase (CSE) produces H2S via enzymatic conversion of L-cysteine and plays a critical role in cardiovascular homeostasis. We investigated the effects of genetic modulation of CSE and exogenous H2S therapy in the setting of pressure overload-induced heart failure. Methods and Results-: Transverse aortic constriction was performed in wild-type, CSE knockout, and cardiac-specific CSE transgenic mice. In addition, C57BL/6J or CSE knockout mice received a novel H2S donor (SG-1002). Mice were followed up for 12 weeks with echocardiography. We observed a >60% reduction in myocardial and circulating H2S levels after transverse aortic constriction. CSE knockout mice exhibited significantly greater cardiac dilatation and dysfunction than wild-type mice after transverse aortic constriction, and cardiac-specific CSE transgenic mice maintained cardiac structure and function after transverse aortic constriction. H2S therapy with SG-1002 resulted in cardioprotection during transverse aortic constriction via upregulation of the vascular endothelial growth factor-Akt-endothelial nitric oxide synthase-nitric oxide-cGMP pathway with preserved mitochondrial function, attenuated oxidative stress, and increased myocardial vascular density. Conclusions-: Our results demonstrate that H 2S levels are decreased in mice in the setting of heart failure. Moreover, CSE plays a critical role in the preservation of cardiac function in heart failure, and oral H2S therapy prevents the transition from compensated to decompensated heart failure in part via upregulation of endothelial nitric oxide synthase and increased nitric oxide bioavailability. © 2013 American Heart Association, Inc.

Gruionu G.,Harvard University | Hoying J.B.,Cardiovascular Innovation Institute | Pries A.R.,Charité - Medical University of Berlin | Secomb T.W.,University of Arizona
Microcirculation | Year: 2012

Objective: Vascular networks respond to chronic alterations in blood supply by structural remodeling. Previously, we showed that blood flow changes in the mouse GA lead to transient diameter increases, which can generate large increases in circumferential wall stress. Here, we examine the associated changes in the medial area of the arterial wall and the effects on circumferential wall stress. Methods: To induce blood flow changes, one of the two feeding vessels to the GA was surgically removed. At 7-56days after blood flow interruption, the vasculature was perfused with India ink for morphological measurements, and processed for immuno-cytochemistry to mark the medial cross-section area. Theoretical simulations of hemodynamics were used to analyze the data. Results: During adaptive increases in vessel diameter, increases in medial area were observed, most strongly in the middle region of the artery. Simulations showed that this increase in medial area limits the increase in estimated circumferential stress during vascular adaptation to less than 50%, in contrast to an increase of up to 250% if the medial area had remained unchanged. Conclusions: During vascular adaptation, increases in circumferential stress are limited by growth of the media coordinated with diameter changes. © 2012 John Wiley & Sons Ltd.

Krishnan L.,Cardiovascular Innovation Institute | Chang C.C.,Cardiovascular Innovation Institute | Nunes S.S.,Toronto General Research Institute | Williams S.K.,Cardiovascular Innovation Institute | And 2 more authors.
Critical Reviews in Biomedical Engineering | Year: 2013

The microvasculature is a dynamic cellular system necessary for tissue health and function. Therapeutic strategies that target the microvasculature are expanding and evolving, including those promoting angiogenesis and microvascular expansion. When considering how to manipulate angiogenesis, either as part of a tissue construction approach or a therapy to improve tissue blood flow, it is important to know the microenvironmental factors that regulate and direct neovessel sprouting and growth. Much is known concerning both diffusible and matrix-bound angiogenic factors, which stimulate and guide angiogenic activity. How the other aspects of the extravascular microenvironment, including tissue biomechanics and structure, influence new vessel formation is less well known. Recent research, however, is providing new insights into these mechanisms and demonstrating that the extent and character of angiogenesis (and the resulting new microcirculation) is significantly affected. These observations and the resulting implications with respect to tissue construction and microvascular therapy are addressed. © 2013 by Begell House, Inc.

Williams S.K.,University of Arizona | Williams S.K.,Cardiovascular Innovation Institute | Kleinert L.B.,University of Arizona | Kleinert L.B.,Cardiovascular Innovation Institute | Patula-Steinbrenner V.,University of Arizona
Journal of Biomedical Materials Research - Part A | Year: 2011

Development of a small diameter (<6 mm) synthetic vascular graft with clinically acceptable patency must overcome the inherent thrombogenicity of polymers and the development of neointimal thickening. Establishment of an endothelial cell lining on the lumenal surface has been hypothesized as a mechanism to improve the function of vascular grafts. The major aim of this study is to evaluate the use of laminin type 1, covalently bound to all surfaces of expanded polytetrafluoroethylene (ePTFE) grafts, on neovascularization of the interstices and lumenal surface endothelialization. One millimeter i.d. vascular grafts were surface modified through covalent attachment of laminin type 1. Grafts were subsequently implanted as interpositional aortic grafts in rats. Following 5-weeks implantation, the grafts were explanted and morphologically evaluated using scanning electron microscopy and light microscopy. Scanning electron microscopy identified an extensive coverage of antithrombogenic cells on the lumenal flow surface of laminin type 1 modified grafts. Histological evaluation confirmed the presence of endothelial cells on the midgraft lumenal surface of laminin 1 modified grafts. Extensive neovascularization of the interstices of the laminin-modified grafts occurred as compared with control grafts. We conclude that surface modification using laminin type 1 accelerates both the neovascularization and endothelialization of porous ePTFE vascular grafts. Copyright © 2011 Wiley Periodicals, Inc.

Junkin M.,University of Arizona | Lu Y.,University of Arizona | Long J.,University of Arizona | Deymier P.A.,University of Arizona | And 2 more authors.
Biomaterials | Year: 2013

Calcium signaling in the diverse vascular structures is regulated by a wide range of mechanical and biochemical factors to maintain essential physiological functions of the vasculature. To properly transmit information, the intercellular calcium communication mechanism must be robust against various conditions in the cellular microenvironment. Using plasma lithography geometric confinement, we investigate mechanically induced calcium wave propagation in networks of human umbilical vein endothelial cells organized. Endothelial cell networks with confined architectures were stimulated at the single cell level, including using capacitive force probes. Calcium wave propagation in the network was observed using fluorescence calcium imaging. We show that mechanically induced calcium signaling in the endothelial networks is dynamically regulated against a wide range of probing forces and repeated stimulations. The calcium wave is able to propagate consistently in various dimensions from monolayers to individual cell chains, and in different topologies from linear patterns to cell junctions. Our results reveal that calcium signaling provides a robust mechanism for cell-cell communication in networks of endothelial cells despite the diversity of the microenvironmental inputs and complexity of vascular structures. © 2012 Elsevier Ltd.

Krishnan L.,Cardiovascular Innovation Institute | Clayton L.R.,Cardiovascular Innovation Institute | Boland E.D.,Cardiovascular Innovation Institute | Reed R.M.,Cardiovascular Innovation Institute | And 2 more authors.
Transplantation Proceedings | Year: 2011

Immunoisolation strategies have the potential to impact the treatment of several diseases, such as hemophilia, Parkinson's and endocrine disorders, such as parathryroid disorders and diabetes. The hallmark of these disease states is the amelioration of the disease process by replacement of the deficient protein. Naturally, several cellular therapeutic strategies like genetically modified host cells, stem cells, donor cells, or even complex tissues like pancreatic islets have been investigated. Current evidence suggests that successful strategies must incorporate considerations for local hypoxia, vascularity, and immunoisolation. Additional regulatory concerns also include safe localization of implanted therapeutic cells to allow for monitoring, dose adjustment, or removal when indicated. Local hypoxia and cellular toxicity can be detrimental to the survival of freshly implanted pancreatic islets, leading to a need for a larger initial number of islets or repeated implantation procedures. The lack of adequate donors and the large number of islet equivalents needed to achieve euglycemic states amplify the nature of this problem. We have developed a novel immunoisolation device based on electrospun nylon, primarily for islet transplantation, such that the inner component functions as a cellular barrier while allowing diffusion, whereas the outer component can be optimized for tissue integration and accelerated vascularization. Devices explanted after subcutaneous implantation in wild-type B6 mice after a period of 30 days show vascular elements in the outer layer of the electrospun device. The inner layer when intact functioned as an effective barrier to cellular infiltration. The preimplantation of such a device, with a relatively thin inner barrier membrane, will allow for adequate vascularization and reduce postimplantation hypoxia. This study demonstrates the feasibility of an electrospun isolation device that can be easily assembled, modified by varying the electrospinning parameters, and functionalized with surface-active molecules to accelerate vascularization. © 2011 Published by Elsevier Inc.

Chang C.C.,Cardiovascular Innovation Institute | Boland E.D.,Cardiovascular Innovation Institute | Williams S.K.,Cardiovascular Innovation Institute | Hoying J.B.,Cardiovascular Innovation Institute
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2011

Regenerative medicine seeks to repair or replace dysfunctional tissues with engineered biological or biohybrid systems. Current clinical regenerative models utilize simple uniform tissue constructs formed with cells cultured onto biocompatible scaffolds. Future regenerative therapies will require the fabrication of complex three-dimensional constructs containing multiple cell types and extracellular matrices. We believe bioprinting technologies will provide a key role in the design and construction of future engineered tissues for cell-based and regenerative therapies. This review describes the current state-of-the-art bioprinting technologies, focusing on direct-write bioprinting. We describe a number of process and device considerations for successful bioprinting of composite biohybrid constructs. In addition, we have provided baseline direct-write printing parameters for a hydrogel system (Pluronic F127) often used in cardiovascular applications. Direct-write dispensed lines (gels with viscosities ranging from 30 mPa s to greater than 600 × 10 6 mPa s) were measured following mechanical and pneumatic printing via three commercially available needle sizes (20 ga, 25 ga, and 30 ga). Example patterns containing microvascular cells and isolated microvessel fragments were also bioprinted into composite 3D structures. Cells and vessel fragments remained viable and maintained in vitro behavior after incorporation into biohybrid structures. Direct-write bioprinting of biologicals provides a unique method to design and fabricate complex, multicomponent 3D structures for experimental use. We hope our design insights and baseline parameter descriptions of direct-write bioprinting will provide a useful foundation for colleagues to incorporate this 3D fabrication method into future regenerative therapies. © 2011 Wiley Periodicals, Inc.

Nunes S.S.,Cardiovascular Innovation Institute | Krishnan L.,Cardiovascular Innovation Institute | Gerard C.S.,Spinal USA | Dale J.R.,Cardiovascular Innovation Institute | And 5 more authors.
Microcirculation | Year: 2010

We have demonstrated that MFs isolated from adipose retain angiogenic potential in vitro and form a mature, perfused network when implanted. However, adipose-derived microvessels are rich in provascularizing cells that could uniquely drive neovascularization in adipose-derived MFs implants. Objective: Investigate the ability of MFs from a different vascular bed to recapitulate adipose-derived microvessel angiogenesis and network formation and analyze adipose-derived vessel plasticity by assessing whether vessel function could be modulated by astrocyte-like cells. Methods: MFs were isolated by limited collagenase digestion from rodent brain or adipose and assembled into 3D collagen gels in the presence or absence of GRPs. The resulting neovasculatures that formed following implantation were assessed by measuring 3D vascularity and vessel permeability to small and large molecular tracers. Results: Similar to adipose-derived MFs, brain-derived MFs can sprout and form a perfused neovascular network when implanted. Furthermore, when co-implanted in the constructs, GRPs caused adipose-derived vessels to express the brain endothelial marker glucose transporter-1 and to significantly reduce microvessel permeability. Conclusion: Neovascularization involving isolated microvessel elements is independent of the tissue origin and degree of vessel specialization. In addition, adipose-derived vessels have the ability to respond to environmental signals and change vessel characteristics. © 2010 John Wiley & Sons Ltd.

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