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","Doctor of Philosophy (Ph.D.)","College of Medicine","Burnett School of Biomedical Sciences","Biomedical Sciences"]},{"key":"dc:description.abstract","label":"Abstract","values":["We previously demonstrated that embryonic stem (ES) cells over-expressing tissue inhibitor of metalloproteinase-1 (TIMP-1) have increased potential to engraft and differentiate into cardiac myocytes following transplantation into the infarcted heart. However, the ability of TIMP-1 to activate endogenous stem cells and enhance their differentiation into cardiac regenerative cell types is still unknown. We postulate that TIMP-1 may additionally activate a stem cell population that enhances cardiac cell type differentiation in the infarcted myocardium. To prove this hypothesis, we isolated c-kit+ve cells from four weeks old C57BL/6 mice and cultured them in vitro in presence of ES conditioned media (ESCM), ES-TIMP-1-CM or TIMP-1. Our immunostaining data validate the existence of a novel CD63+ve/c-kit+ve cells. When treated with TIMP-1, these cells showed significantly (p < 0.05) increased proliferation and differentiation into cardiac myocytes, vascular smooth muscle cells, and endothelial cells. Western blot analysis revealed significantly (p < 0.05) increased expression of CD63, phosphorylated and total β-catenin proteins. Furthermore, our RT-PCR data showed increased cardiac gene expression (GATA-4, Mef2C, and Nkx-2.5) when compared to ESCM and control cells. Based on the in vitro findings, we investigated the effect of intramyocardial delivery of TIMP-1 on endogenous CD63+ve/c-kit+ve cells following myocardial infarction (MI). C57BL/6 and TIMP-1 KO mice underwent coronary artery ligation followed by intramyocardial delivery of 20μl of culture media (CC), ESCM, ES-TIMP-1-CM or TIMP-1. Subsequent immunohistochemistry analysis demonstrated the presence of a CD63+ve/c-kit+ve cell population within the peri-infarct area and confirmed intramyocardial delivery of ES-TIMP-1-CM or TIMP-1 significantly (p < 0.05) enhanced their proliferation. Percentage of CD63+ve/c-kit+ve cells was significantly (p < 0.05) lower in TIMP-1 KO mice compared to C57BL/6 animals. RT-PCR analysis revealed TIMP-1 KO animals expressed significantly less CD63 and TIMP-1 mRNAs compared to C57BL/6 mice. Activated CD63+ve/c-kit+ve cells were also able to differentiate into major cardiac cell types as previously shown in vitro. The differentiation potential of these cells was however higher in C57BL/6 mice compared to TIMP-1 KO mice. We also demonstrate that CD63+ve/c-kit+ve cells differentiation is regulated by CD63/β-catenin pathway in vivo. Additionally, we provide evidence that TIMP-1 protects the heart from adverse cardiac remodeling through inhibition of cardiac apoptosis and fibrosis leading to significantly (p < 0.05) improved contractile function. Collectively, our data show TIMP-1 plays a dual protective role in the MI heart. It activates a unique stem cell population, CD63+ve/c-kit+ve, which proliferates and differentiates into functional myocytes, smooth muscle cells and endothelial cells mediated through CD63/β-catenin pathway. TIMP-1 also protects the heart from adverse cardiac remodeling. Increased cardiac regeneration and inhibition of adverse cardiac remodeling consequently lead to restored cardiac function."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["TIMP-1 Activates a Unique Cardiac Stem Cell Population, CD63+ve/C-KIT+ve, Thereby Enhancing Cardiac Differentiation, and Protects the Heart From Adverse Cardiac Remodeling Following Myocardial Infarction"]}]}],"canonical_facts":{"dc:contributor":["Singla, Dinender"],"dc:creator":["Abdelli, Latifa"],"dc:description":["If this is your thesis or dissertation, and want to learn how to access it or for more information about readership statistics, contact us at STARS@ucf.edu
","Doctor of Philosophy (Ph.D.)","College of Medicine","Burnett School of Biomedical Sciences","Biomedical Sciences"],"dc:description.abstract":["We previously demonstrated that embryonic stem (ES) cells over-expressing tissue inhibitor of metalloproteinase-1 (TIMP-1) have increased potential to engraft and differentiate into cardiac myocytes following transplantation into the infarcted heart. However, the ability of TIMP-1 to activate endogenous stem cells and enhance their differentiation into cardiac regenerative cell types is still unknown. We postulate that TIMP-1 may additionally activate a stem cell population that enhances cardiac cell type differentiation in the infarcted myocardium. To prove this hypothesis, we isolated c-kit+ve cells from four weeks old C57BL/6 mice and cultured them in vitro in presence of ES conditioned media (ESCM), ES-TIMP-1-CM or TIMP-1. Our immunostaining data validate the existence of a novel CD63+ve/c-kit+ve cells. When treated with TIMP-1, these cells showed significantly (p < 0.05) increased proliferation and differentiation into cardiac myocytes, vascular smooth muscle cells, and endothelial cells. Western blot analysis revealed significantly (p < 0.05) increased expression of CD63, phosphorylated and total β-catenin proteins. Furthermore, our RT-PCR data showed increased cardiac gene expression (GATA-4, Mef2C, and Nkx-2.5) when compared to ESCM and control cells. Based on the in vitro findings, we investigated the effect of intramyocardial delivery of TIMP-1 on endogenous CD63+ve/c-kit+ve cells following myocardial infarction (MI). C57BL/6 and TIMP-1 KO mice underwent coronary artery ligation followed by intramyocardial delivery of 20μl of culture media (CC), ESCM, ES-TIMP-1-CM or TIMP-1. Subsequent immunohistochemistry analysis demonstrated the presence of a CD63+ve/c-kit+ve cell population within the peri-infarct area and confirmed intramyocardial delivery of ES-TIMP-1-CM or TIMP-1 significantly (p < 0.05) enhanced their proliferation. Percentage of CD63+ve/c-kit+ve cells was significantly (p < 0.05) lower in TIMP-1 KO mice compared to C57BL/6 animals. RT-PCR analysis revealed TIMP-1 KO animals expressed significantly less CD63 and TIMP-1 mRNAs compared to C57BL/6 mice. Activated CD63+ve/c-kit+ve cells were also able to differentiate into major cardiac cell types as previously shown in vitro. The differentiation potential of these cells was however higher in C57BL/6 mice compared to TIMP-1 KO mice. We also demonstrate that CD63+ve/c-kit+ve cells differentiation is regulated by CD63/β-catenin pathway in vivo. Additionally, we provide evidence that TIMP-1 protects the heart from adverse cardiac remodeling through inhibition of cardiac apoptosis and fibrosis leading to significantly (p < 0.05) improved contractile function. Collectively, our data show TIMP-1 plays a dual protective role in the MI heart. It activates a unique stem cell population, CD63+ve/c-kit+ve, which proliferates and differentiates into functional myocytes, smooth muscle cells and endothelial cells mediated through CD63/β-catenin pathway. TIMP-1 also protects the heart from adverse cardiac remodeling. Increased cardiac regeneration and inhibition of adverse cardiac remodeling consequently lead to restored cardiac function."],"dc:format":["application/pdf"],"dc:identifier":["CFE0005750"],"dc:identifier.uri":["https://stars.library.ucf.edu/etd/1198"],"dc:language":["English"],"dc:subject":["Myocardial infarction; cardiac stem cells; timp 1; c kit; cd63; Catenin; proliferation; differentiation","Medical Sciences","Dissertations, Academic -- Medicine; Medicine -- Dissertations, Academic"],"dc:title":["TIMP-1 Activates a Unique Cardiac Stem Cell Population, CD63+ve/C-KIT+ve, Thereby Enhancing Cardiac Differentiation, and Protects the Heart From Adverse Cardiac Remodeling Following Myocardial Infarction"],"dc:type":["Doctoral Dissertation (Open Access)"]},"updated_at":"2026-07-24T05:09:59Z"}