Human bone marrow platelet progenitors express and release endothelin-1

Abstract

Because it has been shown that human platelet precursors from normal bone marrow express preproendothelin-1 (ET-1) mRNA, this investigation was designed to find out whether these cells could synthesize and release mature ET-1 and express ET receptors. Therefore, we examined the expression of endothelin-converting enzyme (ECE) mRNA and of mRNAs for ET receptors in cells purified from normal bone marrow and measured immunoreactive (ir)ET in their culture medium. RT-PCR applied to RNAs from platelet precursors yielded amplified fragments of the expected sizes of 567, 428, and 299 bp for ECE, ETB and ETA receptors, respectively. These cells released ir-ET into the culture medium in a time-dependent fashion. These results raise the possibility of autocrine actions of the intrinsic ET system in bone marrow platelet precursor cells.