Application of novel tissue microarrays to investigate expression of tryptase, chymase and KIT protein in placental mast cells.
BACKGROUND
Tissue microarrays comprise numerous small representative tissue samples from hundreds of different cases assembled on a single histologic slide, and therefore allow high throughput analysis of multiple specimens at the same time. Mast cells are paracrine cells found ubiquitously in connective tissue. Expression of the serine proteases tryptase and chymase, as well as KIT protein, the receptor for stem cell factor (SCF), has been demonstrated in mast cells. Because little is known about the role of mast cells in the placenta, we investigated the number and expression of chymase, tryptase, and KIT protein in placental mast cells using newly developed tissue microarrays.


METHODS
Tissue microarrays were prepared from archival paraffin tissue blocks of 90 placentae, including 15 normal ones as a control group. Gestational age of the placentae ranged from 7 to 42 weeks. Sections of formalin-fixed paraffin-embedded material were prepared on chemically activated cover-slides. The slides were cut in 4-mm(2) squares containing representative areas, and transferred to a tissue microarray. Hematoxylin and eosin (H&E), chloroacetate esterase (CAE), toluidine blue, periodic acid--Schiff (PAS), and immunohistochemical staining were performed. The number of mast cells and expression of chymase, tryptase, and KIT protein were evaluated in each case.


RESULTS
Mast cell numbers in placentae with inflammation/abortion exceeded that of normal placentae. Although statistically not significant, we furthermore observed an increase in chymase-positive mast cells in the group of placentae associated with fetal malformations/chromosomal aberrations compared with normal placentae.


CONCLUSIONS
Novel tissue microarray technique has been introduced into placental research, and allows multiple placental tissue samples to be effectively analyzed simultaneously. This study indicated an increased number of chymase-positive mast cells in placentae with fetal malformation/chromosomal aberration. Activation of angiotensin II by chymase may play a role in fetal malformation. Moreover, it has been speculated that mast cells may only express chymase (MC(C)). Our findings denote the presence of placental MC(C). However, further studies are needed to elucidate more precisely the role of mast cell chymase in the placenta.
Noack
Frank
F
Department of Pathology, University Hospital Schleswig-Holstein, Campus Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany. noack@patho.uni-luebeck.de
Krüger
Stefan
S
Thorns
Christoph
C
Finas
Dominique
D
Stöcker
Winfried
W
Diedrich
Klaus
K
Horny
Hans-Peter
HP
D000328:Adult; D015415:Biomarkers / Q000032:analysis*; D053818:Chymases; D005260:Female; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008407:Mast Cells / Q000737:chemistry* / Q000473:pathology; D010920:Placenta / Q000737:chemistry* / Q000473:pathology; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis; D012697:Serine Endopeptidases / Q000032:analysis; D019089:Stem Cell Factor / Q000032:analysis; D046888:Tissue Array Analysis / Q000379:methods*; D053802:Tryptases
D015415:Biomarkers; D019089:Stem Cell Factor; D019009:Proto-Oncogene Proteins c-kit; D012697:Serine Endopeptidases; D053818:Chymases; D053802:Tryptases