Development and characterisation of elastomeric block copolymeric substrates for myocardial tissue engineering using embryonic stem cell derived cardiomyocytes

Cardiac patches comprised of embryonic stem cell derived cardiomyocytes (ESC-CMs) attached to biodegradable polymeric substrates were developed for patients suffering from heart attacks. Cardiomyocytes were derived from mouse and human embryonic stem cell (ESC). Thermoplastic elastomeric (TPE) block co-polymers poly(ethylene terephthalate)/dilionic acid (PET/DLA), a relatively slow degrading biomaterial, served as substrates to deliver cardiomyocytes and to further support the myocardium after an infarct. Additionally, titanium dioxide (TiO2) nanoparticles (NPs) (mean size 23 nm), were incorporated in the PET/DLA polymer in a concentration of 0.2wt%. Results showed TiO2 NPs to effect polymer mechanical properties, increasing material stiffness and tensile strength. The surface roughness and hydrophilicity of the biomaterial also increased upon addition of TiO2 NPs. It was found that 0.2wt% TiO2 NP addition enhanced cellular adhesion, spread and proliferation. A fibroblastic cell line, used to test proliferation, proliferated on both biomaterials with and without pre-gelatin coating. Lactate dehydrogenase (LDH) release into culture media, used as a marker of cell death did not differ significantly between biomaterials and tissue culture plastic (TCP). The cytotoxicity of TiO2 NPs on adult cardiomyocytes, hESC-CMs and fibroblasts was also investigated at various concentrations (0-150 ppm) chosen based on their relevance for the intended application of the biomaterial. At 10 ppm the particles had no significant acute effect on cardiac contractility of either adult rat heart cells or hESC-CM. However, functional activity was significantly reduced, in terms of beating rate, over longer culture periods (4h). Further improvements were carried out to enhance the properties of the patch. The investigation included: i) lactide addition to the polymer to increase polymer degradation rate and ii) topographical surface changes introduced by a phase separation micromoulding technique (PSμM). Newly developed biomaterial was faster degrading (as measured by biomaterial %weight loss) and simultaneously encouraged fibroblast proliferation. Finally the biomaterials have been investigated ex vivo and in vivo by collaborators at NHLI (Imperial College London). The results have confirmed that the developed biomaterials in conjunction with cardiomyocytes from ESCs are promising for applications in myocardial tissue engineering (MTE) strategies with no adverse effect on cardiac functionality detected.EThOS - Electronic Theses Online ServiceGBUnited Kingdo