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Evaluating Chemotaxis of Epidermal Keratinocyte Migration

Keratinocytes: The Key Supporter of the Skin Barrier

Keratinocytes are the most common cell type of the skin. They are present in the epidermis, which is the outermost layer of the skin, responsible for forming a barrier against the external environment and preventing water loss. The keratinocytes you see on your skin are mostly corneocytes, terminally differentiated keratinocytes that are continually shed from the outer layer of skin and replaced from below by new corneocytes. Keratinocytes are also key players in wound healing. They migrate to the wound site and fill the space formed by the wound. In response to injury, they are also responsible for recruiting immune cells to the wound site.

A New Study Using Lifeline® Keratinocytes in Chemotaxis Research

Chemotaxis is the process by which cells migrate in response to a chemical gradient, which can act as either chemoattractant or chemorepellent. For example, when a wound occurs, various growth factors and chemokines are released at the site, which recruit neutrophils and phagocytes via chemotaxis. Following this initial recruitment, fibroblasts are attracted to the site via gradients of platelet-derived growth factor, and during the re-epithelialization phase, slow-moving keratinocytes migrate over the wound to reestablish the skin barrier. Although the stages of wound healing are well understood, the factors that regulate keratinocyte migration over the wound bed are relatively unknown.

In addition, the current methods for studying slow-moving chemotaxis in vitro are not designed for high-throughput analyses. To address this challenge, Tomasova and colleagues set out to develop a new migration assay to study slow-moving chemotaxis in 2D and 3D applications. Their new chemotaxis chamber was based on the m-Slide Chemotaxis microfluidic tool, which they modified to contain a hydrogel microstructure, designated a migration arena.

The authors first tested that the migration arena would support formation of a chemical gradient. Using fluorescent dyes, they showed that gradients were stable for over 72 hours. Next, the authors measured chemotaxis of HT-1080 fibrosarcoma cells, which migrated toward gradients of fetal bovine serum (FBS) in both 2D and 3D environments.

The group then evaluated the chemotaxis of Lifeline® normal human epidermal keratinocytes (NHEKs) in response to epidermal growth factor receptor (EGF), transforming growth factor b (TGFb), TGFa, insulin, and bovine pituitary extract (BPE). Of these factors, NHEKs had a chemotactic response to the two EGF receptor (EGFR) ligands, EGF and TGFa over the course of 20 hours. Finally, using an inhibitor against EGFR (AG-1478), the authors showed that NHEK chemotaxis in response to TGFa and EGF was EGFR-dependent.

Together, the results of this study demonstrate that Chemotaxis of slow-moving cells can be measured over long periods of time in the modified m-Slide Chemotaxis chamber. Additionally, the authors illustrated that both TGFa and EGF are chemoattractants for NHEKs.

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Check in with us every other week here on the blog. If you are using Lifeline® products in your research, we want to know about it — send us your study and it could be featured in our next Blog!

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