Publication Date

2010-04-22

Availability

Open access

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Molecular and Cellular Pharmacology (Medicine)

Date of Defense

March 2010

First Committee Member

Fulvia Verde, Ph.D. - Committee Chair

Second Committee Member

John Barrett, Ph.D. - Committee Member

Third Committee Member

Paul Schiller, Ph.D. - Committee Member

Fourth Committee Member

Danuta Szczesna-Cordary, Ph.D. - Committee Member

Fifth Committee Member

Keith A Webster, Ph.D. - Mentor

Sixth Committee Member

Howard Prentice, Ph.D. - Outside Committee Member

Abstract

Reduction of cardiac myocyte loss and repair of the vasculature post myocardial infarction are important therapeutic goals because the potential for intrinsic repair is limited. Preclinical and limited clinical data support the possibility that bone marrow-derived mesenchymal stem cells may be a suitable cell type for cellular therapy. The goal of this research was to determine the effectiveness of using MSCs from aged mice in cellular therapy for the treatment of AMI. The central hypothesis for this research was that therapeutic potential of mesenchymal stem cells decreases with age. This research utilized global gene expression analysis to investigate molecular differences in MSCs harvested from three different age groups of mice. Microarray analysis was performed to investigate changes in gene expression with respect to aging. Furthermore, both in vitro and in vivo experiments were completed to analyze the functional and molecular characteristics of the MSCs. The data identified age-related defects in mouse MSCs as well as determined the molecular basis for these deficiencies. This study indicates that MSCs from 26m mice are severely deficient in the induction of angiogenesis and cardiac repair due to defective paracrine factor secretion caused by decreased expression of growth factor/cytokine genes. Hypoxia attenuates the deficiency in the aged mice, whereas in young mice low oxygen promotes secretion of paracrine growth factors. It was determined a dysfunction in HIF-1 alpha signaling was present in MSCs from 26m mice and is regulated by the PI3K/Akt signaling in MSCs. Furthermore, two novel and important and novel aspects of this study were the discovery that cell cycle regulation gene expression decreases with age and MSCs have increased insulin resistance with age. Increased insulin resistance in this cell type with aging is likely to have profound effects on the clinical outcomes of using these cells therapeutically. Likewise, loss of cell cycle regulation during proliferation could also lead to undesirable clinical effects. Gaining insight to the repair potential of these cells with respect to age will help to better define future trials of autologous stem cells not only for heart disease but for all of the many applications proposed for these cells.

Keywords

P53; VEGF; RT-PCR; Nuclear Translocation; Hindlimb Ischemia

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