Characterization of upper lamina propria interstitial cells in bladders from patients with neurogenic detrusor overactivity and bladder pain syndrome.
Bottom Line: The ULP IC were characterized ultrastructurally by the presence of actin filaments with densifications, many caveolae and abundant rough endoplasmic reticulum (RER); on immunohistochemistry ULP IC were immunoreactive for α-sma, vimentin, CD10 and podoplanin and categorized as interstitial Cajal-like cells (ICLC).In both groups there was also an increased presence in ULP lymphocytes.Their unique α-sma(+) /desmin(-) /CD34(-) phenotype allows studying this population in various bladder disorders.
Affiliation: KU Leuven, Department of Morphology and Molecular Pathology, Leuven, Belgium. Thomas.Gevaert@uz.kuleuven.ac.beShow MeSH
Related in: MedlinePlus
Mentions: When visualized with the light microscope the ULP reveals an IC population that is organized in 10–20 densely packed layers (Fig. 3) and characterized by a vesicular, rather round nucleus and scant eosinophilic cytoplasm. Remarkable regional differences in development of IC were present: within a single section areas of densely packed IC layers alternated with regions that contained only few ULP IC. Ultrastructurally the ULP cells contained caveolae in the peripheral cell membrane and well-developed rough endoplasmic reticulum, mitochondria and peripheral actin filaments (mostly organized in bundles as illustrated by the frequently observed densifications) in the cytoplasm (Figs 1 and 2, Table 2). The cells also showed several discontinuous plasmalemmal thickenings, but no clear fibronexus was seen. Intercellular connections consisted preferentially of intermediate junctions although occasional gap junctions were also observed (data not shown). Immunohistochemical characterization of ULP IC revealed the expression of vimentin, α-sma, podoplanin and CD10 (Figs 3 and 4). Anti-CD10 antibodies only labelled the upper cell layers. This cell population was negative for desmin, CD34 (Figs 3 and 4) and neurofilament (not shown). C-kit-immunoreactivity was clearly detected in several mast cells in the ULP area, as confirmed by a tryptase staining; no clear expression in ULP IC was found (Fig. 5). We cannot exclude the presence of sparse c-kit+ IC in the ULP because a fluorescence double-staining c-kit/tryptase failed, due to technical reasons; nevertheless most c-kit+ cells in the ULP were mast cells in our observations. CD34 expression was found in IC both in the lower parts of the lamina propria (excluding the ULP IC population) as well as in IC between the detrusor smooth muscle bundles. Thus ULP IC constitute a unique cell population expressing vimentin and α-sma, but not desmin nor CD34 (Figs 3 and 6).
Affiliation: KU Leuven, Department of Morphology and Molecular Pathology, Leuven, Belgium. Thomas.Gevaert@uz.kuleuven.ac.be