Wound healing is impaired in aging with consequent delay in closure and increased risk for dehiscence and infection. This age-associated impairment in wound repair is due, in part, to delayed neovascularization. The successful growth of new blood vessels requires coordinated cellular functions including migration, proliferation, and biosynthesis/breakdown of matrix proteins. Although each of these processes may be impaired in aging, our preliminary data show that decreased migration of microvascular endothelial cells contributes to delayed angiogenesis. The long-term objective of this proposal is to define the mechanism(s) of impaired migration in aged endothelial cells, and thus, identify potential sites for interventions to improve wound healing in aging. In vitro, migration of aged human microvascular endothelial cells (hmEC) is slowed on collagen I, the major extracellular matrix (ECM) protein present during the angiogenic phase of wound repair. Optimal migration of cells requires the dynamic breaking and forming of cell-matrix contacts. Thus, movement is regulated by matrix degrading proteases (such as interstitial collagenase- matrix metalloprotease I, MMP1), integrins (such as alpha2beta1, which induces MMP1 upon binding to collagen I), and their interaction with the ECM. Aged hmEC express less MMP1 and secrete increased amounts of tissue inhibitor of metalloprotease 1 (TIMP1) relative to young hmEC. Moreover, in vivo, delayed neovascularization of polyvinyl alcohol sponges in aged mice is associated with decreased MMP1 and increased TIMP1 expression. Stimulation of aged hmEC with vascular endothelial growth factor (VEGF) increases their movement, an effect which may result from induction of MMP1. The hypothesis of this application is that aged hmEC have impaired migration due to decreased synthesis of MMP1. We propose that alpha2beta1-collagen I binding does not properly function to induce MMP1 synthesis which is necessary for selective detachment during migration. Moreover, as MMP1 is required to generate ligation sites for alpha2beta1, selective attachment cannot occur in a coordinated fashion. Using young hmEC and young mice as controls, the following Specific Aims are proposed: 1. Elucidate the role of MMP1/TIMP1 in the impaired migration of aged hmEC on collagen I. 2. Define the expression and function of alpha2beta1, and its interaction with MMP1, in impaired attachment and migration of aged hmEC. 3. Identify the mechanism by which VEGF enhances the migration of aged hmEC. 4. Determine the effects of age and VEGF on: expression and function of MMP1/TIMP1 and alpha2beta1, and the migration of microvascular EC during angiogenesis in vivo.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG015837-02
Application #
6169095
Study Section
Pathology A Study Section (PTHA)
Program Officer
Kohanski, Ronald A
Project Start
1999-05-01
Project End
2004-04-30
Budget Start
2000-05-01
Budget End
2001-04-30
Support Year
2
Fiscal Year
2000
Total Cost
$196,200
Indirect Cost
Name
University of Washington
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
Bentov, Itay; Damodarasamy, Mamatha; Plymate, Stephen et al. (2013) B16/F10 tumors in aged 3D collagen in vitro simulate tumor growth and gene expression in aged mice in vivo. In Vitro Cell Dev Biol Anim 49:395-9
Reed, May J; Vernon, Robert B (2012) Miniaturized assays of angiogenesis in vitro. Methods Mol Biol 843:87-98
Reed, May J; Damodarasamy, Mamatha; Vernon, Robert B (2011) Angiogenesis In Vitro Utilizing Murine Vascular Explants in Miniaturized 3-Dimensional Collagen Gels. Open Circ Vasc J 4:12-17
Damodarasamy, Mamatha; Vernon, Robert B; Karres, Nathan et al. (2010) Collagen extracts derived from young and aged mice demonstrate different structural properties and cellular effects in three-dimensional gels. J Gerontol A Biol Sci Med Sci 65:209-18
Eyman, D; Damodarasamy, M; Plymate, S R et al. (2009) CCL5 secreted by senescent aged fibroblasts induces proliferation of prostate epithelial cells and expression of genes that modulate angiogenesis. J Cell Physiol 220:376-81
Sprenger, C C; Plymate, S R; Reed, M J (2008) Extracellular influences on tumour angiogenesis in the aged host. Br J Cancer 98:250-5
Reed, May J; Eyman, Daniel; Karres, Nathan (2008) Nitric oxide effects on the function of aged cells ex vivo and in vivo. In Vivo 22:673-9
Reed, May J; Karres, Nathan; Eyman, Daniel et al. (2007) Culture of murine aortic explants in 3-dimensional extracellular matrix: a novel, miniaturized assay of angiogenesis in vitro. Microvasc Res 73:248-52
Hamner, Margaret A; Vernon, Robert B; Gooden, Michel D et al. (2005) Elongation and secretion of tissue inhibitor of metalloproteinases 1 by human microvascular endothelial cells cultured in collagen gels is stimulated by mitomycin c. Endothelium 12:97-101
Reed, May J; Koike, Teruhiko; Puolakkainen, Pauli (2003) Wound repair in aging. A review. Methods Mol Med 78:217-37

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