258 IDENTIFICATION OF TELOCYTES IN THE UPPER LAMINA PROPRIA OF THE HUMAN

Abstract

INTRODUCTION AND OBJECTIVES: The upper lamina propria (ULP) area of interstitial cells (IC) has been studied extensively in bladder, but is rather unexplored in the rest of the urinary tract. In bladder these cells are characterized as interstitial Cajal-like cells (ICLC). This cell layer is intriguing because of the localization directly underneath the urothelium, the intercellular contacts and the close relation with nerve endings and capillaries. METHODS: In the present study we examined the ULP layer of IC in human renal pelvis, ureter and urethra. Tissue was obtained from normal areas in nephrectomy-, cystectomyand prostatectomy-specimens, and processed for morphology, immunohistochemistry and electron microscopy. A morphological and immunohistochemical phenotype for the ULP IC was assessed and region-dependent differences were looked for. RESULTS: The ULP IC in renal pelvis, ureter and urethra had a similar ultrastructural phenotype,which differed from that of bladder ICLC, i.e., thinner and longer cytoplasmic processes, no peripheral actin filaments, and presence of dense core granules and microtubules. Together with their immunohistochemical profile, these features are most compatible with the phenotype of telocytes (1), a recently discovered group of mesenchymal cells. The most striking immunohistochemical finding was the variable expression of estrogen receptor (ER) and progesterone receptor (PR). CONCLUSIONS: We characterized the ULP IC in human renal pelvis, ureter and urethra as telocytes. These telocytes are ultrastructurally different from ULP ICLC in human bladder and have a regiondependent immunohistochemical profile. The functional relevance of ULP telocytes and ULP ICLC in the urinary tract remains to be elucidated, and ER and PR might therefore be promising pharmacological research targets. (1) Popescu LM, Faussone-Pellegrini MS. TELOCYTES a case of serendipity: the winding way from Interstitial Cells of Cajal (ICC), via Interstitial Cajal-Like Cells (ICLC) to TELOCYTES. J Cell Mol Med. 2010; 14:729-40.