The impact of transient heat transfer on tissue culture cell distribution

Abstract

It is common practice to subculture adherent eukaryotic cells in multi-well plates at room temperature before 37 °C incubation for growth. Under these conditions, cell distribution was non-uniform with a higher density of cells near the edges of the wells. Non-uniform cell density can alter cell behaviour in numerous biological assays and can result in variability when using automated plate readers on intact cells. This study investigated the possibility that the non-uniform cell distribution was caused by temperature gradients in the growth medium and well walls. Cell density analyses revealed significantly greater cell densities near well walls. Temperature distribution was documented using infrared imaging and temperature-sensitive LCD films, and a transient heat transfer mathematical model was developed to characterise the system and compared to the cell density results. The model predicts that an initial less-than-1 °C temperature gradient is present in the well shortly after initiating 37 °C incubation, leading to preferential cell adhesion to the warmer edges of wells in the first ∼30 min of incubation. Techniques to remediate non-uniform cell distribution were evaluated, and a simple method proved effective to promote uniform cell densities across wells of 24-well plates.