Studies on skeletal muscle stem cell biology of the apolipoprotein E deficient mice

Barlow, Joseph James

Abstract

Skeletal muscle has tremendous adaptive and regenerative ability, this is achieved through a resource of stem cells which remain present in adults. These cells remain quiescent until activated by myogenic factors, at which point they proliferate and then differentiate into new fibres. To guide this process, the muscle stem cells express different transcription factors: Pax7 when quiescent, MyoD when activated and during proliferation, and Myogenin during differentiation. The present work focuses on the muscle stem cell function of the of the Apolipoprotein E deficient (ApoE-/-) mouse, and aims to understand the influence of hyperlipidaemia, as well as senescence on muscle stem cell function.
This thesis uses the atherosclerotic ApoE deficient mouse model, to determine the muscle stem cell function. Muscles of wild type and ApoE deficient mice were dissected, and single fibres or stripped stem cells were cultured to determine the expression patterns of Pax7, MyoD and Myogenin or the proliferation and differentiation capacity respectively. Regeneration of injured muscle was also studied in vivo by staining injured muscle of wild type and ApoE mice to detect necrotic fibres, regenerating fibres, and macrophage infiltration. Experimental hyperlipidaemia was induced in cultured myoblasts by culturing with palmitate to determine the influence of oxidative stress in hyperlipidaemia by applying the antioxidant ebselen. Senescence was induced in cultured myoblasts by adding doxorubicin to culture media to determine the proliferation and differentiation capacity of senescent muscle stem cells. Releasate of activated human platelets was applied to senescent cells as a treatment to promote regeneration.
The thesis shows that hyperlipidaemia results in impaired myogenic progression, and muscle stem cells have reduced capacity for both proliferation and differentiation, this is underlined by the fact that the ApoE deficient mouse had impaired recovery after muscle injury. Furthermore, the influence of oxidative stress in hyperlipidaemia was highlighted as the antioxidant ebselen restored muscle stem cell function in culture. Senescence using doxorubicin greatly inhibited proliferation and differentiation of muscle stem cells, and application of growth factors released from activated platelets only partially restored function.

Citation

Barlow, J. J. Studies on skeletal muscle stem cell biology of the apolipoprotein E deficient mice. (Thesis). Hull York Medical School, the University of Hull and the University of York. https://hull-repository.worktribe.com/output/4224384

• Thesis Type: Thesis
• Deposit Date: Oct 19, 2022
• Publicly Available Date: Feb 24, 2023
• Keywords: Medicine
• Public URL: https://hull-repository.worktribe.com/output/4224384
• Additional Information: Hull York Medical School, The University of Hull and the University of York
• Award Date: Oct 1, 2022