Immunohistochemical markers of neural progenitor cells in the early embryonic human cerebral cortex.

The development of the human central nervous system represents a delicate moment of embryogenesis. The purpose of this study was to analyze the expression of multiple immunohistochemical markers in the stem/progenitor cells in the human cerebral cortex during the early phases of development.  To this end, samples from cerebral cortex were obtained from 4 human embryos of 11 weeks of gestation. Each sample was formalin-fixed, paraffin embedded and immunostained with several markers including GFAP, WT1, Nestin, Vimentin, CD117, S100B, Sox2, PAX2, PAX5, Tß4, Neurofilament, CD44, CD133, Synaptophysin and Cyclin D1. Our study shows the ability of the different immunohistochemical markers to evidence different zones of the developing human cerebral cortex, allowing the identification of the multiple stages of differentiation of neuronal and glial precursors. Three important markers of radial glial cells are evidenced in this early gestational age: Vimentin, Nestin and WT1. Sox2 was expressed by the stem/progenitor cells of the ventricular zone, whereas the postmitotic neurons of the cortical plate were immunostained by PAX2 and NSE. Future studies are needed to test other important stem/progenitor cells markers and to better analyze differences in the immunohistochemical expression of these markers during gestation.

WT1 expression in the human fetus during development.

Wilms' Tumor 1 (WT1) is a transcription factor involved in the development of the urogenital system. The purpose of this study was to analyze the immunoreactivity for WT1 protein in different tissues and organs in human fetuses in early phases of gestation. To this end, samples from multiple organs were obtained from 4 human fetuses, ranging from 7 up to 12 weeks of gestation. Each sample was formalin-fixed, paraffin embedded and immunostained for WT1. Our data show that WT1 is involved in development of multiple human organs in a more vast series of cells types than previously reported. Immunostaining for WT1 was characterized by a predominant cytoplasmic reactivity in the vast majority of cell types. Mesenchimal progenitors in the fetal lung, ductal plate progenitors in fetal liver, cap mesenchimal cells in the developing kidney, fetal zone cells in adrenal glands, atrial and ventricular cardiomyocytes in the fetal heart, radial glial cells in the fetal cerebral cortex and skeletal muscle cell precursors showed the highest levels of WT1 immunoreactivity. Future studies will be needed to detect differences in the expression of WT1 in various organs at different gestational ages, in order to better evaluate the role of WT1 in cell proliferation and differentiation during intrauterine human development.

[A case of pleural mesothelioma caused by unusual occupational exposure to asbestos in the wool industry]. / Un caso di mesotelioma pleurico da inusuale esposizione professionale ad amianto nell'industria della lana.

We report the case of a 73-year-old worker who died of pleural mesothelioma, after being employed for 35 years in a wool textile plant of Biella (Italy). Close investigations revealed that he provided for the maintenance of materials and machines. In particular, he used to replace asbestos parts such as rings, joints and insulations of pipelines (dyeing unit), as well as brake linings of warping, looming and combing machines. Beside confirming the importance of an accurate occupational anamnesis to recognize work-induced cancers, the case draws the attention on the risk of mesothelioma in the wool industry, an occupational setting that is not usually considered as a potential source of exposure to asbestos fibres. Such pollution might explain the increased mortality due to pleural mesothelioma in the Biella area (characterized by a prosperous textile industry), reported in previous epidemiological studies.