Transglutaminases, involucrin, and loricrin as markers of epidermal differentiation in skin substitutes derived from human sweat gland cells.
OBJECTIVE
In a multi-project research line, we are currently testing whether a morphologically and functionally near normal epidermis can be cultured from human sweat gland (SG) cells and be used as a skin substitute. The present study focuses on the stratum corneum of the epidermis that assumes a vital barrier function for the skin. The main process in the formation of the cornified cell envelope in human epidermis, i.e. crosslinking of proteins and lipids, is catalyzed by several transglutaminases (TG). Therefore, we compared the expression patterns of various TG and their substrates in SG-derived versus keratinocyte-derived epidermal substitutes.


METHODS
Sweat gland cells, keratinocytes, and fibroblasts were isolated from human skin samples and cultivated separately to generate epidermal substitutes. These were transplanted onto the back of athymic rats. After 2 weeks, the transplants were excised and analyzed histologically as well as by indirect immunofluorescence. We looked at the expression of TG1, 3, 5, and their substrates involucrin and loricrin (=markers of epidermal differentiation) in SG-derived and keratinocyte-derived skin substitutes as well as in normal skin.


RESULTS
The SG cell-derived epidermis was near normal anatomically, formed a cornified cell envelope and demonstrated TG1, 3, and 5 as well as involucrin and loricrin expression patterns similar to those found in keratinocyte-derived epidermis and normal control skin.


CONCLUSIONS
These findings support the thesis that SG cells have the potential to form a near normal stratified epidermal analog that might be used as a skin substitute. The expression of TG1 and 3, not normally expressed in human SG, suggests the presence of re-programmed SG cells and/or stem cells capable of both de novo generating and maintaining an epidermis.
Tharakan
Sasha
S
Tissue Biology Research Unit, Department of Surgery, University Children's Hospital, Zurich, Switzerland.
Pontiggia
Luca
L
Biedermann
Thomas
T
Böttcher-Haberzeth
Sophie
S
Schiestl
Clemens
C
Reichmann
Ernst
E
Meuli
Martin
M
D000293:Adolescent; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D004195:Disease Models, Animal; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism / Q000637:transplantation; D005260:Female; D015200:Fluoroimmunoassay; D006801:Humans; D007223:Infant; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D011923:Rats, Nude; D017768:Skin, Artificial; D013545:Sweat Glands / Q000166:cytology* / Q000378:metabolism; D011503:Transglutaminases / Q000378:metabolism*; D014945:Wound Healing; D014947:Wounds and Injuries / Q000378:metabolism / Q000628:therapy
D015415:Biomarkers; D008565:Membrane Proteins; D011498:Protein Precursors; C064554:loricrin; C032253:involucrin; D011503:Transglutaminases