Abdominal aortic aneurysms (AAAs), characterized by degrading aortic elastin matrix and resultantvessel weakening and rupture, causes 15,000 deaths in the United States anually, primarily amongstseniors, and those suffering from inherited matrix disorders. Regression of existing aneurysms byrestoring healthy elastin architecture is difficult since adult cells poorly synthesize elastin and no toolsare available to induce faithful elastin regeneration. Thus, our long-term goal is to investigatestrategies to enable elastin regeneration within AAAs, so as to delay or eliminate surgical intervention. We determined that elastogenic cues based on tetramers of hyaluronan (HA), a matrixglycosaminoglycan, and TGF- synergestically upregulate elastin matrix synthesis and assembly byhealthy adult vascular smooth muscle cells, and to a lesser extent by aneurysmal cells. The outcomesportend tremendous utility of these cues to similar elastin regeneration within AAs. However,recruitment and crosslinking of soluble elastin precursors into a stable matrix is inefficient and must beup-regulated, an insufficiency we propose to address. Our objective is thus to investigate impact ofsuch cues (LOX, an elastin crosslinking enzyme, and Cu2+ ions), provided concurrent to or independentof elastogenic cues, on elastin synthesis, matrix assembly, and cell phenotype (e.g., elastase and MMPrelease) by cultured healthy and aneurysmal adult rat aortic SMCs (RASMCs). We also seek toinvestigate the efficacy of the optimized cues for elastin matrix regeneration in induced rat AAAs. In each of three proposed aims, we will in parallel investigate an 'endogenous model' of elastinmatrix regeneration, wherein RASMCs (healthy and aneurysmal) will be provided cues to bothsynthesize, and assemble and crosslink tropoelastin precursors. In the exogenous model, SMCs(healthy and aneurysmal) will be provided LOX and Cu2+ cues only to upregulate cellular assemblyand maturation of exogenous tropoelastin.
Aim 1 will investigate dose-specific benefits of exogenous,LOX to elastin synthesis, matrix assembly, and cell phenotype, within RASMC cultures.
Aim 2 willevaluate dose-specific effects of copper ion delivery from copper nanoparticles (CuNP), concurrent withoptimized LOX cues, to LOX activity and to elastin synthesis and matrix assembly and cell phenotypewithin RASMC cultures. Finally, aim 3 will test utility of optimized crosslinking cues (LOX, Cu2+) for insitu cellular assembly of elastin matrices, to stabilize induced rat aortic aneurysms (AAs) in variousstages of development, when tropoelastin is (A) endogenously prompted by elastogenic cues, or (B)exogenously supplied. We expect the project outcomes to offer more effective treatment options for AAAs, based on bothin situ regeneration and stabilization of elastin matrices that may be employed as a stand-alone optionor in consort with existing surgical or future pharmacological approaches. Other applications of theproject outcomes, specifically those pertaining to studies of healthy vascular cells, includeaugumenting elastin synthesis, assembly, and matrix quality within tissue engineered constructs,restoring elastin homeostasis in de-elasticized vascular allografts and xenografts, and possibly evenserving as in vitro models to investigate elastogenesis during early morphogenesis, and wound healingin adult vessels.
Abdominal aortic aneurysms (AAAs) are potentially fatal conditions afflicting major blood vessels, which are characterized by a loss of blood vessel wall flexibility, and their ultimate structural weakening and rupture. This occurs due to breakdown and loss of rubber-like protein fibers (elastin) that normally help vessels restore their shape and form after deformation. Since cells within blood vessels cannot themselves produce new elastin, this study proposes to provide cells in culture, or within living blood vessels, a combination of biological molecules that will either induce cells to (a) synthesize new soluble elastin building blocks (precursors) and further assemble them into fiber structures, or (b) only assemble elastin precursors that are also simultaneously provided to them. The project outcomes can significantly benefit the development of new, non-surgical treatment strategies that can halt progress of or even regress existing AAAs by coaxing cells within to regenerate new elastin structures or repair and stabilize existing ones.
Showing the most recent 10 out of 22 publications
