Author

Rebecca Jones

Date of Award

Spring 2019

Document Type

Open Access Dissertation

Department

Biomedical Engineering

First Advisor

Richard L. Goodwin

Abstract

Collagen type I represents a novel material for three-dimensional in vitro models. While two-dimensional models are typically inadequate for recreating the complex processes of the body, collagen provides a three-dimensional basis with a variety of applications, including remodeling of vascular cells under tension and vascular stenosis. Smooth muscle cells reorganize and reconstruct their environment differently under conditions of tensions, such as with sutures, or under conditions without applied external tension. Vascular stenosis, the abnormal narrowing of blood vessels, arises from defective developmental processes or atherosclerosis-related adult pathologies. Stenosis triggers a series of adaptive cellular responses that induces adverse remodeling, which can progress to partial or complete vessel occlusion with numerous fatal outcomes. Despite its severity, the cellular interactions and biophysical cues that regulate this pathological progression are poorly understood. Here, we report the design and fabrication of a three-dimensional (3D) in vitro system to model cellular tension from sutures and vascular stenosis so that specific cellular interactions and responses to hemodynamic stimuli can be investigated. Tubular cellularized constructs (cytotubes) were produced, using a collagen casting system, to generate a straight cylindrical model in addition to stenotic arterial model. Spatial distribution of cells remained more even in cylindrical cytotubes that were sutured compared to those without applied tension. Fabrication methods were developed to create cytotubes containing single- and co-cultured vascular cells, where cell viability, distribution, morphology, and contraction were examined. Fibroblasts, bone marrow primary cells, smooth muscle cells (SMCs), and endothelial cells (ECs) remained viable during culture and developed location- and time-dependent morphologies. We found stenotic cytotube contraction to depend on cellular composition, where SMC-EC co-cultures adopted intermediate contractile phenotypes between SMC- and EC-only cytotubes. Our fabrication approach and the resulting in vitro and artery models can serve as 3D culture systems to investigate vascular pathogenesis and promote the tissue engineering field.

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