Browsing by Subject "Stromal Cells"
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Item Adipose-Derived Stromal Cells Contribute To Spinal Cord Repair But Are Not Neural-Crest Derived Stem Cells(2007-08-08) Wrage, Philip Charles; Tansey, Malú G.Neurodegeneration and injury to the nervous system are characterized by a loss of neurons - and often supporting glia - at the afflicted site. Neurons of the adult CNS are terminally differentiated, non-mitotic cells that are connected within specific circuits. These characteristics present a challenge to the development of treatments for degeneration or injury of the nervous system. The limited spatial distribution, as well as limited migration and differentiation potentials of adult NSCs, severely restrict the ability of adult NSCs to contribute to repair or regeneration in the wake of injury or degenerative disease progression. Adipose-derived adult stromal (ADAS) cells have been reported to give rise to cells of both mesodermal and ectodermal origin (e.g. osteocytes, chondrocytes, cardiac myocytes, neurons, and glia) and are easily harvested and cultured in vitro. Neural crest derived tissues have the extraordinary capacity to give rise to a wide range of tissue types: neurons and glia of the peripheral nervous system, adrenal glands, chondrocytes and osteocytes of the head and neck, smooth muscle cells of the cardiac outflow tract, and melanocytes among others. Given the reported ability of neural crest-derived cells and ADAS cells to give rise to bone, cartilage, muscle, and nerve tissues, I hypothesized that ADAS cells might be neural crest-derived cells that had migrated to the periphery, had remained resident within the adipose tissue of adult mammals, and had maintained early developmental plasticity. This hypothesis was not supported by lineage tracing experiments. Additionally, I found that ADAS cells were not capable of differentiating into functional neurons in vitro or in an in vivo model of spinal cord injury. However, ADAS cells altered the growth inhibitory environment of the lesioned cord and contributed to axon migration despite their inability to undergo neural differentiation. Based on these results, further research is warranted into the mechanisms by which ADAS cells create a growth permissive environment in the lesioned spinal cord.Item Characterizing Renal Interstitial Heterogeneity and Its Role in Nephron Patterning(2020-08-01T05:00:00.000Z) England, Alicia Rachel; Marciano, Denise; Carroll, Thomas J.; Cleaver, Ondine; Petroll, W. Matthew; Varner, VictorChronic kidney disease (CKD) is a growing national health concern affecting 30 million Americans. CKD can lead to permanent loss of kidney function requiring treatment for survival, yet the only two treatment options, dialysis and transplant, are unable to meet the needs of the millions impacted. There are numerous efforts to engineer renal replacement therapy tissue yet most focus primarily on the nephron (the functional unit of the kidney) and the vasculature. Although these efforts are exciting, they face two significant obstacles. First, current progenitor cell-based technologies have only produced relatively immature tissues. Second, most efforts have overlooked the importance of renal stroma, a cell type that not only impacts the development of the renal parenchyma, but which also plays a crucial role in kidney physiology as well as having multiple endocrine functions. Using a combination of single-cell ribonucleic acid sequencing (scRNA-seq) and messenger RNA (mRNA) in situ hybridization we have found that the mouse embryonic renal stroma is a molecularly heterogeneous population of cells with different cell types occupying anatomically distinct positions that correlate with anatomically and functionally distinct regions of the adjacent parenchyma. We find that human fetal kidney interstitium shows a similar degree of heterogeneity to the mouse extending this phenomenon beyond our model system. Further, we find that beta-catenin has a cell-autonomous role in the development of a medullary subset of the interstitium and that this non-autonomously affects the development of the adjacent tissue. These data suggest stromal sub-types establish unique microenvironmental niches that provide signals which regulate the differentiation/segmentation of the nephron. We find that interstitial heterogeneity is evident at the earliest stages of renal development, and that interstitial patterning develops independent of signals from the nephron tubules. Using a novel nephrogenic zone cell differentiation assay, we find a subpopulation preferentially promotes proximal tubule differentiation and non-autonomously promotes proliferation. These data highlight a functional role of the renal interstitium in renal development that cannot be ignored in current renal regeneration efforts.Item The Functional Roles of Rho-Kinase and Matrix Metalloproteinases in Regulating Corneal Stromal Cell Mechanics in 3-D Collagen Matrices(2013-11-26) Zhou, Chengxin; Grinnell, Frederick; Petroll, W. Matthew; Luby-Phelps, Katherine; Tang, Liping; Alexandrakis, GeorgiosThe main focus of my research has been on understanding the biomechanical and biochemical mechanisms of cell-extracellular matrix (ECM) interactions during corneal wound healing, which may allow the development of new therapeutic strategies to promote corneal regeneration. Previous studies have established that the Rho GTPases play a central role in regulating the cytoskeletal changes associated with cell mechanical activity. A novel force monitoring system was successfully developed to investigate the role of Rho in corneal cell force generation in 3-D collagen matrices. Maximum tractional force generated by 9 million corneal fibroblasts in serum culture was around 265 Dynes. Inhibition of Rho kinase by Y-27632 induced a 69% force reduction. These results demonstrated that Rho/Rho kinase play a key role in mediating contractile force generation of corneal stromal fibroblasts in serum culture. I also investigated the functions of Rho GTPase signaling in corneal stromal fibroblast migration and cell-ECM interactions using a 3-D nested matrix construct. The experimental results showed that both the amount and the speed of corneal fibroblast migration and local collagen matrix reorganization were significantly inhibited by Y-27632. Following the inhibition, cells extended thinner dendritic processes into the outer matrix, and generated tractional forces at their leading edge. However, cells were unable to generate contractile forces needed to retract their tail and pull the cell body forward through the collagen matrix. I also studied the role of Matrix metalloproteinases (MMPs) in corneal cell mechanics, since these have been recognized as an influential component in extracellular matrix turnover and corneal repair. I first assessed the expression and collagenolytic activities of MMPs by primary corneal keratocyte in response to different signaling factors. I then studied the functions of MMPs in regulating keratocyte migration, cell-induced matrix contraction, and cell protrusive activity in 3-D collagen matrices. This study suggested that, in serum free PDGF culture, although collagenolysis was limited to a pericellular scale, primary corneal keratocytes utilized MMPs to facilitate cell migration, ECM contraction, cell spreading in 3-D collagen matrices. Thus MMPs may play a key role in facilitating cell-collagen matrix interactions by corneal keratocytes, without producing widespread disruption of corneal ECM structure.