Collective Cell Migration in Wound Healing

Following a wound, epithelial cells migrate collectively to heal. During healing, “leader cells” begin to form at the free edge and migrate as finger-like, multi-cellular protrusions into the wound boundary. While the presence of leader cells is well documented, factors contributing to their formation is not well understood. Standard wound healing assays often culture cells against a physical barrier, and cells migrate to the free space once the barrier is removed. However, the role of time in culture against a barrier in leader cell formation has not been studied. To address this, a monolayer of Human Keratinocytes (HaCaTs) is seeded against PDMS barriers. The time in culture is varied to study its effect on cell force, motion, wound closure, distribution of actin, and the presence of leader cells following barrier removal by using traction force microscopy and fluorescent imaging. With increased time against a barrier, the number of leader cells increased, a multi-cellular actin cable was formed at the leading edge, and cell migration speeds decreased. The resulting data point to the importance of time in culture in altering cellular mechanics to affect wound healing and add new understanding of factors affecting formation of leader cells in collective cell migration.