Stem cells and regenerative medicine for congenital heart disease

Abstract

Congenital heart diseases are the most common congenital defects worldwide. Materials used for corrective surgery such as the biologic scaffold cormatrix are inherently non-contractile and cannot meet the dynamic growth of the heart. Seeding cormatrix with cells showed superior results but this approach is limited by short durability of cells in-vivo which is not well understood. We investigated the effect of seeding cormatrix with triad of cells including Wharton jelly mesenchymal stem cells (WjMSCs), human umbilical vein endothelial cells (HUVECs) and human cardiac fibroblasts (HCFs). Then to examine their mutual interaction to understand and also anticipate their in-vivo behaviour. The three cell phenotypes were characterised using morphology and expression of specific markers in addition to wjMSCs trilineage differentiation. Then conditioned media (CdM) were used to examine the mutual cell interaction. We used immunofluorescence to assess protein expression, qPCR for mRNA, flowcytometry for apoptosis/cell death assay and BrdU assay to assess cell proliferation. The CdM effects were quite variable. It did enhance pro-survival and angiogenic factors of wjMSCs, did not support survival or angiogenic profile of HUVECs while mostly neutral effect on HCFs. We attempted to boost the patch’s cellular properties using small molecules. So, we trialled to differentiate wjMSCs to cardiomyocytes using 5-azacitidine. This trial failed to show any cardiac differentiation. Then, we examined effects of the GSK-3 inhibitor CHIR99021 on the triad of cells and extended the assessment to the combined effect of CHIR99021 and CdM (CHIR/CdM) which showed better survival of wjMSCs and HUVECs while still neutral effect on HCFs. Finally, cormatrix uptake of this combination of cells was tested using H&E, cells viability using live/dead cell staining and surface topography using scanning electron microscope. Also effect on mechanical properties of the patch was examined using tensile stress machine. Cormatrix proved biocompatible with the triad of cells and maintained its mechanical elasticity. The next step would be to test this patch in clinically relevant large animal model.

Date of Award	28 Sept 2021
Original language	English
Awarding Institution	University of Bristol
Supervisor	Mohamed Ghorbel (Supervisor) & Massimo Caputo (Supervisor)