Parting the cellular sea: electrotaxis evoked directional separation of co-cultured keratinocytes and fibroblasts

Bioelectric communication plays a significant role in several cellular processes and biological mechanisms, such as division, differentiation, migration, cancer metastasis, or wound healing. The flow of ions through cellular walls and the gradients generated thereby evoke this signaling as electric fields (EFs) form across membranes, and their changes act as cues for cells. An EF is natively generated towards the wound center during epithelial wound healing, aiming to align and guide cell migration, particularly of keratinocytes, fibroblasts, and macrophages. While this phenomenon, known as electrotaxis, has been extensively investigated across many cell types, it is typically explored one cell type at a time, which does not accurately represent cellular interactions during complex biological processes. Here we show the co-cultured electrotaxis of epithelial keratinocytes and fibroblasts with a salt-bridgeless microfluidic approach for the first time. The electrotactic response of these cells was first assessed in mono-culture to establish a baseline, resulting in a characteristic anodic migration for keratinocytes and cathodic for fibroblasts. Both cell types retained their electrotactic properties in co-culture leading to clear cellular partition. The methods leveraged herein can pave the way for future co-culture electrotaxis experiments where the concurrent influence of cell lines can be thoroughly investigated.