Less Is More: The RPE Cell Culture Medium Additive THT Mildly Impairs RPE Health

THT is an additive for culture medium used to maintain retinal pigment epithelial (RPE) cells. The individual components of THT are taurine, hydrocortisone, and triiodothyronine. The effects of THT on RPE health had not been defined. To determine how THT affects RPE cell physiology, we grew induced pluripotent stem cell (iPSC)-derived RPE cells with a normal concentration of THT ("high" THT) or in a medium with a lower concentration of THT (low THT). We determined the impact of THT on the extracellular flux of glucose, lactate, palmitate, and VEGF. We assessed RPE function by measuring trans-epithelial electrical resistance (TEER). RPE cells grown in low THT are more glycolytic, oxidize fatty acids more slowly, have a higher TEER, and release more VEGF basally than RPE cells grown in high THT. Our findings show that THT impacts metabolism and function. Further studies will be needed to fully define the impact of each THT component on RPE metabolism, function, and health.