Transforming growth factor beta, pleiotropic regulator of hematopoietic stem cells: Potential physiological and clinical relevance

Transforming growth factor beta (TGF-beta) is a pleiotropic regulator of al l stages of hematopoieis. Depending on the differentiation stage of the tar get cell, the local environment, and the concentration of TGF-beta, TGF-bet a can be proproliferative or antiproliferative, proapoptotic or antiapoptot ic, and/or prodifferentiative or antidifferentiative. TGF-beta is the major regulator of stem cell quiescence and can act directly or indirectly throu gh effects on the marrow microenvironment. In addition, paracrine and autoc rine actions of TGF-beta have overlapping but distinct regulatory effects o n hematopoietic stem/progenitor cells. Neutralization of autocrine TGF-beta has therapeutic potential. (C) 2001 The Japanese Society of Hematology.