Mesenchymal stem cells (MSCs) have great potential to improve clinical outcomes for many inflammatory and degenerative diseases through delivery of exogenous MSCs via injection or cell-laden scaffolds and through mobilization and migration of endogenous MSCs to injury sites. MSC fate and function is determined by microenvironmental cues, specifically dimensionality, topography, and cell-cell interactions. MSC responses of migration and differentiation are the focus of this dissertation. Cell migration occurs in several physiological and pathological processes; migration mode and cell signaling are determined by the environment and type of confinement in three-dimensional (3D) models.
Tendon injury is a common musculoskeletal disorder that occurs through cumulative damage to the extracellular matrix (ECM). Studies combining nanofibrous scaffolds and MSCs to determine an optimal topographical environment have promoted tenogenic differentiation under various conditions. We investigated cellular response of MSCs on specifically designed nanofiber matrices fabricated using a novel spinneret-based tunable engineered parameters production method (STEP). We designed suspended and aligned nanofiber scaffolds to study cellular morphology, tendon marker gene expression, and matrix deposition as determinants for tendon differentiation.
The delivery and maintenance of MSCs at sites of inflammation or injury are major challenges in stem cell therapies. Enhancing stem cell homing could improve their therapeutic effects. Homing is a process that involves cell migration through the vasculature to target organs. This process is defined in leukocyte transendothelial migration (TEM); however, far less is known about MSC homing. We investigated two population subsets of MSCs in a Transwell system mimicking the vasculature; migrated cells that initiated transmigration on the endothelium and nonmigrated cells in the apical chamber that failed to transmigrate. Gene and protein expression changes were observed between these subsets and evidence suggests that multiple signaling pathways regulate TEM.
The results of these experiments have demonstrated that microenvironmental cues are critical to understanding the cellular and molecular mechanisms of MSC response, specifically in homing and differentiation. This knowledge has identified scaffold parameters required to stimulate tenogenesis and signaling pathways controlling MSC homing. These findings will allow us to target key regulatory molecules and cell signaling pathways involved in MSC response towards development of regenerative therapies. / Ph. D. / Stem cell therapy is one way to improve tissue injury and inflammatory conditions, but to optimize such therapy, we need to study how the environment around cells influence turning them into the injured tissue and how to control their movement to these sites in order for mesenchymal stem cells (MSCs) to exert their therapeutic functions. MSCs move through and detect their environment through the material around them, including organization of the fibers they attach to and neighboring cells. Cell migration is an important cell behavior that occurs in normal and diseased processes. MSCs have great potential to improve clinical outcomes for many inflammatory and degenerative diseases whether through delivery of exogenous MSCs or through mobilization and migration of endogenous MSCs to injury sites.
Tendon damage can occur slowly over time and optimal treatment for normal function after injury remains unknown. Equine MSCs were harvested from bone marrow and subjected to scaffolds of different fiber orientation to study whether cells develop characteristics of tendon cells. Cellular responses were similar between scaffolds of aligned fiber orientation. Manipulation of equine bone marrow MSCs through the use of specifically designed nanofiber scaffolds aid in understanding the mechanisms by which the cells respond and function in tendon development, injury, and repair.
Inflammation is a necessary process after tissue injury; however, it must progress in a controlled manner and be resolved before it leads to tissue damage and dysfunction. MSCs function in regulating the effects of inflammation and immune cells; however, getting them to these sites and keeping them there remains challenging. MSCs adhere to and migrate through capillaries towards these sites, known as stem cell homing. Human bone marrow MSCs were loaded onto human synovial microvascular endothelial cells to study migration towards an inflammatory stimulus. This stimulus acted on the endothelial cells to produce another stimulus that attracted MSCs to the endothelial cells. These actions resulted in complete MSC migration through the endothelial cells and activated intracellular signals that can be used to increase the number of MSCs that reach the inflammatory sites and stimulate tissue-healing effects.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/78789 |
| Date | 31 August 2017 |
| Creators | Popielarczyk, Tracee |
| Contributors | Veterinary Medicine, Barrett, Jennifer G., Nain, Amrinder, Huckle, William R., Eyestone, Willard H. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf, application/x-zip-compressed, application/x-zip-compressed, application/pdf, application/x-zip-compressed |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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