Doctoral Degrees (General Internal Medicine)

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Browsing Doctoral Degrees (General Internal Medicine) by Author "Seboko, Ascentia Mathapelo"

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    miRNA signature of healthy vs impaired mesenchymal stem cells as a biomarker for autologous stem cell therapy
    (Stellenbosch : Stellenbosch University, 2021-12) Seboko, Ascentia Mathapelo; Van de Vyver, Mari; Scholefield, Janine; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Medicine.
    ENGLISH ABSTRACT: Background: Globally, approximately 463 million adults are living with diabetes. This growing prevalence of diabetes places an increased burden on the health systems of low-to-middle income countries such as South Africa. The pathological microenvironment associated with diabetes leads to severe co-morbidities that include chronic foot ulcers. Non-healing ulcers affect approximately 15% of diabetic patients. Novel approaches in the treatment of chronic ulcers make use of mesenchymal stem cell (MSC) therapies. However, autologous MSCs from diabetic patients are less successful than allogeneic donor MSCs. This is due to the impairment of MSCs as result of the pathological diabetic environment. MicroRNAs (miRNAs) have gained immense popularity as biomarkers of disease and have been associated with the development of metabolic diseases. This study hypothesised that MSCs with compromised therapeutic potential, have a unique miRNA signature that could potentially be used as a biomarker to predict if a specific patient would be a good candidate for autologous MSC therapy. Methods: Three models were utilised: 1) Healthy control and impaired diabetic bone marrow MSCs (BMSC) isolated from wildtype (C57BL6/J) and obese diabetic B6.Cg-Lepob/J (ob/ob) mice. BMSC function was assessed by comparing the a) ex vivo growth rate, b) secreted and intracellular IL6 (ELISA), and c) osteogenic (Alizarin Red S staining) and adipogenic (Oil Red O staining) differentiation capacity. Broad miRNA profiling (> 600 miRNAs) was performed using the NanoString mouse v1.5 miRNA Expression Assay (BMSCs) and RT-qPCR (whole blood). 2) Synthetic miRNA mimics were transfected into C3H10T1/2 cells with subsequent assessment of cellular proliferation and migration capacity. 3) The expression of miRNAs of interest was assessed in the serum and PBMCs of overweight/obese (OW/OB) (n=14) and diabetic (n=16) patients who were subdivided into: a) predicted good healers and b) predicted poor healers based on serum MMP9 levels. Health, lifestyle, and dietary questionnaires were completed by participants and blood samples collected to determine their metabolic (blood glucose, HbA1c) profile. Results: The miRNA profile of BMSCs was affected by both sex (male vs female) and metabolic phenotype (healthy vs impaired). MSC impairment was prominent in male ob/ob mice and coincided with the upregulation of 19 miRs and downregulation of 3 miRs compared to their healthy control counterparts (p < 0.05). Five miRNAs of interest (miR-142-5p, miR-200b, miR-202-5p, miR-384-3p and miR-466g) emerged as having a potential role in the functional capacity of BMSCs. C3H10T1/2 cells transfected with miR-202-5p had an increased proliferation rate (p < 0.01) compared to non-transfected cells. All 5 miRNAs of interest reduced the rate of wound closure in vitro following transfection (p < 0.05) compared to non-transfected cells. This was due to more random migration patterns and a reduction in directionality. No association could be observed between the metabolic profile, predicted healing capacity and miRNA expression in the PBMCs of participants. Conclusion: The data confirmed that a unique miRNA signature exists between healthy vs impaired BMSCs. Numerous confounding factors, including sex-specific differences, make the use of these miRNAs as biomarkers unlikely. This study did, however, confirm a role of miRNAs in BMSCs function.