Date of Award

Fall 2021

Document Type

Open Access Dissertation

Department

Biomedical Science

First Advisor

Jay D. Potts

Abstract

The use of three-dimensional (3D) culture systems (hydrogels) and adipose-derived stem cells (ADSCs) in regenerative medicine to advance early-stage investigation and modeling of the mechanisms of diseases, treatments, targets, etc. has recently increased. ADSCs, specifically, are utilized due to their innate programming during embryogenesis and in adult tissues in addition to their ability to differentiate into mesodermal, endodermal, and ectodermal cell-specific lineages. Of importance is that these advancements do not involve a model specimen (i.e. mice or rats) and simulate the numerous conflicting signals a migrating cell is exposed to in vivo such as chemokines, extracellular matrix (ECM), growth factors, and physical forces. However, our understanding of the cellular integration of these signals is lacking. We previously developed a novel self-organizing cellularized collagen hydrogel model that is adaptable, tunable, reproducible, and capable of mimicking the multitude of stimuli that cells experience. Our model formed toroids of cells around 24h, while data we present suggests initial migration as early as 3hr after seeding. Toroid formation appears to be a near universal process with the exception being the cancer cell lines we have tried (<4). Interestingly, when cells are seeded inside the hydrogel, there is contraction of the gel, but no toroid is formed. We observed differences in the cell-cell and cell-ECM interactions in response to a changing microenvironment. Moreover, using rheology, collagen binding peptides, and scanning electron microscope (SEM), we found variation in the remodeling of hydrogels when comparing toroid gels to gels with cells embedded. Lastly, we sought to define the underlying signaling pathways that regulate ADSC directed migration and toroid formation by dissecting the CXCL12-CXCR4 pathway. This work will begin to establish toroid formation as a novel, 3D model for high-throughput investigation of diverse molecular mechanisms and disease progression.

Rights

© 2021, Austin N. Worden

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