Growth factors direct mesenchymal stem cell fate and therapeutic potential

Houlihan, Diarmaid Dominic (2015). Growth factors direct mesenchymal stem cell fate and therapeutic potential. University of Birmingham. Ph.D.

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Abstract

Murine mesenchymal stem cells (MSCs) isolated by plastic adherence contain contaminating cells and have poor growth and differentiation. I report a detailed protocol outlining the steps to prospectively isolate a pure and potent MSC population from murine bone marrow based on their expression of stem cell antigen-1 (Sca-1) and platelet derived growth factor- alpha (PDGFRα) (PαS cells) using flow cytometry. PαS MSCs have augmented growth potential and robust tri-lineage differentiation compared to plastic adherent cells. They exert potent immunosuppressive effects on proliferating naive CD4+ T cells, which is mediated via the production of nitric oxide (NO). Nevertheless, prolonged culture results in cellular senescence, loss of adipogenic differentiation and reduced immunosuppressive properties. Addition of growth factors to standard media (SM) produced significant genotypic and phenotypic changes. Cells cultured in SM supplemented with basic fibroblast growth factor (bFGF) and platelet derived growth factor-BB (PDGF-BB) were primed towards fat and cartilage, but had reduced immunosuppressive potential. In contrast, cells cultured with transforming growth factor-beta (TGF-β) had reduced tri-lineage potential but potent immunosuppressive properties that endured despite long term culture. I demonstrate using novel tissue engineering techniques that bFGF PαS MSCs generate substantial 3-D cartilage pellets. These data have implications for MSC therapy in humans.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):