Modulating the mechanical properties of the extracellular matrix to direct the differentiation of mesenchymal stem cells

Charlton, Laura (2020) Modulating the mechanical properties of the extracellular matrix to direct the differentiation of mesenchymal stem cells. PhD thesis, University of Glasgow.

Due to Embargo and/or Third Party Copyright restrictions, this thesis is not available in this service.

Abstract

Due to Mesenchymal Stem Cells (MSCs) ability to self-renew and differentiate into multiple different cell types, they have become a focal point in the field of regenerative medicine and tissue engineering. The extracellular matrix (ECM) is a dynamic supporting structure for cells in the body and has the ability to alter a cell’s biochemical processes through mechanotransduction. It has long been shown that there is an ability to change the differentiation profile of MSCs through alterations to the mechanical environment they are exposed to. In this thesis, cell-ECM interactions are utilised to develop methodologies to differentiate MSCs down specific differentiation pathways without the use of differentiation media.
The first method developed in this study focuses on differentiating MSCs down the chondrogenic lineage on a single-cell level with the purview of developing a system in which individual chondrocyte phenotypes can be analysed; as well as creating a cell embedded gel with well-defined chondrogenic expression, that can be translated into an in vivo model. The use of 40 µm patterns confines individual cells and promotes a rounded morphology, further coating with type I collagen and hyaluronic acid showed a decrease in actin intensity and a significant increase in both aggrecan and type II collagen expression; which are prominent markers in chondrogenesis. There was localisation of type II collagen on the outer edge of the cells, indicative of single-cell chondrogenic differentiation.
The second focused on osteogenic differentiation, by developing a fiber structure that can be used to gain large volumes of well controlled, protected structures, with good nutrient diffusion. For this we developed a tuneable two layered microfiber composed of a soft, cell-laden collagen core and stiff alginate shell. It was demonstrated that the mechanical properties of the alginate shell could be altered though the replacement of Ca2+ with Sr2+, which causes the microfibers to slowly stiffen over time. Since it was not possible to isolate some of the potentially influential environmental factors for differentiation, the mode of action is still not clear. However, we were able to create a system that could increase cell proliferation with calcium contained type I collagen-alginate fibers and increase OPN expression with the addition of Sr2+, implying we can “trigger” bone formation.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Mesenchymal stem cells, chondrogenic differentiation, osteogenic differentiation, atomic force microscopy, microfiber extrusion, surface micropatterning.
Subjects: Q Science > QH Natural history > QH301 Biology
Colleges/Schools: College of Science and Engineering > School of Engineering > Biomedical Engineering
Funder's Name: Engineering and Physical Sciences Research Council (EPSRC)
Supervisor's Name: Yin, Professor Huabing
Date of Award: 2020
Embargo Date: 20 April 2023
Depositing User: Laura E Charlton
Unique ID: glathesis:2020-81297
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 23 Apr 2020 08:42
Last Modified: 23 Apr 2020 08:42
URI: http://theses.gla.ac.uk/id/eprint/81297
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