The main findings and results obtained during the course of the project are:
• At the beginning of the project, MNPs were functionalized with a specific antibody to target human heart cells. In parallel, a well-defined protocol for differentiation of cardiomyocytes from human induced pluripotent stem cells (iPSCs) was established, obtaining >95% of pure human cardiomyocytes. In the next step, specific binding and uptake of the MNPs by the human heart cells was confirmed by transmitted electron microscopy (TEM) and Prussian blue assay. My findings indicated that the MNPs had no cytotoxicity effects on the cells and the cardiomyocytes were viable and functional for at least 21 days.
• I then aimed to construct the 3D magnetic human heart tissue. The first step was to validate that the magnetically labelled heart cells can form a viable constructing tissue. For that purpose, the cells were mixed in collagen suspension, and within 48-36 hours after gelation, I could already detect synchronous mechanical activity. I next demonstrated the ability to remotely control cardiomyocyte organization and distribution within a hydrogel by external magnetic fields. Different shapes and sizes of magnets were applied to generate intracellular magnetic forces that allowed the stimulation of the cells to the desired controlled geometries within the collagen hydrogel. The biochemical, morphological, and electrical properties of the generated 3D heart tissues were fully characterized by histological, gene expression, and electrophysiological methods.
• Finally, I focused on monitoring ECM remodeling in the generated 3D human cardiac tissue model by using the powerful tool of Raman spectroscopy. Raman spectra were acquired from a monolayer of human cardiomyocytes and different components in the cells (protein, lipid, DNA) were analyzed.
Final results overview: the unique approach developed in this project enables, for the first time, the construction of 3D human cardiac tissues with geometrically controlled microarchitecture without any supporting structures (such as micro-posts or thin films). Furthermore, it allows non-invasive and non-destructive analysis of cell viability and ECM turnover during cardiac remodelling.
A variety of techniques were employed to complete this project, ranging from the nanoscale where magnetic nanoparticles were functionalised with specific antibody and purified; through extensive cell work where cardiomyocytes were differentiated form human iPSCs – the interactions of the MNPs with the cells were confirmed by TEM and viability assays (such as MTT) – and finally in the macroscale by generating the novel 3D magnetic tissue followed by detailed characterizations by confocal microscopy / immunocytochemistry, optical mapping (calcium handling and multielectrode array) and molecular biology techniques such as quantitative polymerase chain reaction (qPCR).
Dissemination of the results: This work has been presented during 2018 at two international conferences (Gordon Research Conference, Les Diablerets, Switzerland; TERMIS World Congress, Kyoto, Japan) and at three national meetings (BCS Annual Conference, Manchester UK; Satellite meeting on Cardiac Physiology, London UK; and FILM microscopy day at Imperial College London). In addition, a high-level manuscript is currently under preparation to be submitted to high-quality journal.
Outreach activities: On March 2018, this work was selected to be presented in the prestigious and highly competitive STEM for BRITIAN poster competition for early-career researches, where I had the opportunity to present and talk about “Magnetic HEART” project in front of Members of both Houses of Parliament at Westminster, London. In addition, during the two-year funding period, extensive outreach activities were carried out to engage with young students and expose them to different aspects of science. For example, in July 2017 and July 2018 I gave several hands-on demonstrations for high school students as part of the London International Youth Science Forum (LIYSF), held at Imperial College London. In addition, in March 2018, I gave demonstrations to Master students at Imperial College London in the subject of ‘stem cells and microscopy’, encouraging them toward a career in science.
