IN-SITU HYBRIDIZATION OF HUMAN ERYTHROPOIETIN IN PRENATAL AND POSTNATAL KIDNEYS

Due to the transient transcription of the gene of erythropoietin (EPO) in, response to hypoxic stimuli, localization within the cell of orig in in humans has not been possible. Under acutely induced transcriptio n of the EPO gene, through severe bleeding (hematocrit <10%), EPO tran scripts were detected within renal interstitial cells in rodents. Howe ver, by immunohistochemistry or tissue culture, human tubular epitheli al cells or glomerular mesangium have been shown. to produce EPO, sugg esting a species difference. Aiming to investigate the precise locatio n of EPO in intact human kidneys, 38 fetal, infant, and adult kidneys were examined by in situ hybridization. Kidneys from patients with con ditions predisposing to severe hgpoxia and/or induced polycythemia wer e utilized, because under these conditions active EPO mRNA synthesis i s expected. We found specific EPO mRNA transcripts within a small popu lation of cortical interstitial cells of near-term or postnatal kidney s.