C‐kit immunopositive interstitial cells (Cajal‐type) in human myometrium

• Published in: Journal of cellular and molecular medicine Vol. 9; no. 2; pp. 407 - 420
• Main Authors: Ciontea, Sanda M., Radu, E., Regalia, T., Ceafalan, Laura, Cretoiu, D., Gherghiceanu, Mihaela, Braga, R. I., Malincenco, Mariana, Zagrean, L., Hinescu, M. E., Popescu, L. M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.04.2005; John Wiley & Sons, Inc
• Subjects: Actins - analysis; Antigens, CD34 - analysis; Basal lamina; c-Kit protein; Capillaries; Caveolae; CD34 antigen; Cell culture; Cell number; Cells, Cultured; Connective Tissue Cells - chemistry; Connective Tissue Cells - cytology; Connective Tissue Cells - ultrastructure; Electrophysiology; Endometrium; Endoplasmic reticulum; Female; Fluorescent Antibody Technique; Gap Junctions - ultrastructure; Humans; Immunofluorescence; Immunoreactivity; Interstitial cells; Light microscopy; Methylene blue; Methylene Blue - chemistry; Microscopy; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Myocytes; Myocytes, Smooth Muscle - chemistry; Myocytes, Smooth Muscle - cytology; Myocytes, Smooth Muscle - ultrastructure; Myometrium; Myometrium - chemistry; Myometrium - cytology; Myometrium - ultrastructure; Pregnancy; Proto-Oncogene Proteins c-kit - analysis; Toluidine; Transmission electron microscopy; Vimentin; Vimentin - analysis
• ISSN: 1582-1838; 1582-4934
• DOI: 10.1111/j.1582-4934.2005.tb00366.x

Previous reports describing Cajal‐like interstitial cells in human uterus are contradictory in terms of c‐kit immunoreactivity: either negative (but vimentin‐positive) in pregnant myometrium, or positive, presumably in the endometrium. The aim of this study was to verify the existence of human myometrial Cajal‐like interstitial cells (m‐CLIC). Six different, complementary approaches were used: 1) methylene‐blue supravital staining of tissue samples (cryosections), 2) methylene blue and Janus green B vital staining (m‐CLIC and mitochondrial markers, respectively), and 3) extracellular single‐unit electrophysiological recordings in cell cultures, 4) non‐conventional light microscopy on glutaraldehyde/osmium fixed, Epon‐embedded semi‐thin sections (less than 1μm) stained with toluidine blue (TSM), 5) transmission electron microscopy (TEM), and 6) immunofluorescence (IF). We found m‐CLIC in myometrial cryosections and in cell cultures. In vitro, m‐CLIC represented ∼7% of the total cell number. m‐CLIC had 2–3 characteristic processes which were very long (∼ 60 μm), very thin (±0.5μm) and moniliform. The dilated portions of processes usually accomodated mitochondria. In vitro, m‐CLIC exhibited spontaneous electrical activity (62.4 ± 7.22 mV field potentials, short duration: 1.197 ± 0.04ms). Moreover, m‐CLIC fulfilled the usual TEM criteria, the so‐called ‘gold’ or ‘platinum’ standards (e.g. the presence of discontinuos basal lamina, caveolae, endoplasmic reticulum, and close contacts between each other, with myocytes, nerve fibers and/or capillaries etc.). IF showed that m‐CLIC express CD117/c‐kit, sometimes associated with CD34 and with vimentin along their processes. In conclusion, we describe myometrial Cajal‐like interstitial cells that have affinity for methylene blue and Janus green B vital dyes, fulfill (all) TEM criteria, express CD117/c‐kit and have spontaneous electric activity.