The Development of an in vitro 3D Histotypic Model of The Human Eccrine Sweat Gland.

Abstract

The human eccrine sweat gland is present on most body sites and is crucial for thermoregulation. Yet, little is known on the mechanisms that govern its function and its morphogenesis. The main reason for the lack in research with regards to the human eccrine gland is the difficulty in isolation and maintenance of the glands and cells in vitro. Only one other cell line derived from the human eccrine gland has ever been reported, the NCLSG3 cell line. NCL-SG3 cells do not however, function like native eccrine secretory coil cells, and thus a better cell model was required. In this project, a human eccrine secretory coil cell line, the EC23 cell line, was developed, along with 8 clones derived from said cell line. EC23 cells and their clones express a panel of markers characteristic of the human eccrine sweat gland secretory coil cells. Furthermore, calcium fluxes can be elicited by cholinergic stimulation of the cells suggesting retention of the native secretory cell phenotype unlike NCL-SG3 cells. The EC23 cell line is also responsive to adrenergic stimuli to a higher degree than NCL-SG3 cells, especially clone 2, however all the cell lines responded significantly less than primary eccrine secretory coil cells upon isoproterenol stimulation. It was also found that the mesenchyme has a crucial effect in determining the formation of eccrine like down-growths in Matrigel organotypic models seeded with EC23 cells, where organotypics made with adult fibroblasts failed to form down-growths in comparison to neonatal fibroblasts. Furthermore, the co-culture of EC23 cell with keratinocytes enhanced the amount of downgrowth. EC23 cells have the capacity to form branching structures that resemble native eccrine glands in GFR Matrigel supplemented with EGF and EDA, and to a lesser extent BMP4. In conclusion it was demonstrated that the EC23 cells can be used as a model to study the human eccrine gland, in particular the secretory coil.