Optimization of preferential heart drug delivery targeting cardiovascular diseases

Introduction Cardiovascular diseases are the foremost causes of death morbidity in western industrialized countries, which remains a major health issue. Particularly, heart failure (HF) is defined by a defect of the heart pump function and s-blockers are usual treatment. However, no cure exists and 5-years mortality remains high (50%). For this reason, new therapeutic strategies need to be considered. Our strategy relies on targeting cardiomyocytes to deliver therapeutic molecule to restore or improve contractile function. Thus, two peptides, CTP (Cardiac Targeting Peptide) and PCM (Primary CardioMyocyte) previously identified by phage display, exhibited a strong cardiac tropism. Objective This work aims to generate and optimize new cardiac targeting peptides derived from CTP and PCM, to deliver specific drugs in case of HF. Method Neonatal rat ventricular cardiomyocytes (NRVC) were isolated and cultured with modified versions of carboxyfluorescein (6CF)-coupled CTP or PCM. Additionally two 6CF-coupled peptides targeting skeletal muscle cells in Duchenne disease were also studied (Duch1 and Duch2). Flow cytometry analyses were performed to quantify peptide cytotoxicity and cellular uptake as percentage of positive 6CF-loaded cells. In parallel, confocal microscopy was performed to underpin peptide subcellular distribution. Results Modified-peptides CTP1, PCM1, PCM2 and PCM3 exhibited in NRVC culture a significant increase in cellular uptake with a low cytotoxicity effect compared to original peptide versions (approximately 50% increase in uptake and below 30% of dead cells). Although Duch2 displayed a high level of cellular uptake (above 99%) it showed a high cytotoxic effect in NRVC (97% of dead cells). Conclusion This study established that optimization of original CTP or PCM peptide sequences increased cellular uptake efficiency and could putatively raise the potential of heart targeting agents for therapeutic delivery.