Proteomics, single cell and precision therapeutics

Personalized medicine requires both the ability to diagnosis a person and have an appropriate individualized therapeutics or treatment route available. Today, the expectation is that single cell proteomics (SCP) provides data that is critical for drug development and safety and toxicity studies and today, mass spectrometry (MS)-based methods allow the simultaneous assessment of 100s-1000s of proteins per cell. Our group is focusing on the heart and in particular drug screening and cardiotoxicity studies ultimately in human iPSC (hiPSC)-derived cardiomyocytes. hiPSC-derived cardiomyocytes from many individuals provides a means to understanding therapeutic response variability. We have isolated and analyzed hiPSC throughout their differentiation to ensure we have a robust mature hiPSC-cardiomyocytes cultures. The UMAP shows 7 clusters and the driver proteins exclusive to iPSC involved immune regulation, while the transitioning on day 4 and 10 were related to transcription and translation and finally, mature cardiomyocytes at day 21 expressing the key adult isoforms of the cardiac sarcomere (based on ~400 cells per day per biological replicate). However, the day 21 hiPSC-derived cardiomyocytes are composed of several cell types but is dominated by cardiomyocytes (e.g., MYH7, cTnT, ATPA2A, RYR2, PLN and SLC8A1) but also neuronal cells, smooth muscle, skeletal muscle, and epithelial cells. Selective drug treatment compared to vehicle treated 21 day hiPSC-cardiomyocytes had extensive overlap as well as a unique cluster comprised of ~15% of total cells that was unique to drug response. This suggests that only part of the cardiomyocytes was responsive to drug treatment. If this is a generalizable trait, then it will become key to identify the protein drivers that make a subgroup of cardiomyocyte responsive to a drug and determine how to pivot the other to the responsive proteome.