Transforming growth factor beta, pleiotropic regulator of hematopoietic stem cells: potential physiological and...

Transforming growth factor beta (TGF-beta) is a pleiotropic regulator of all stages of hematopoieis. Depending on the differentiation stage of the target cell, the local environment, and the concentration of TGF-beta, TGF-beta can be proproliferative or antiproliferative, proapoptotic or antiapoptotic, and/or prodifferentiative or antidifferentiative. TGF-beta is the major regulator of stem cell quiescence and can act directly or indirectly through effects on the marrow microenvironment. In addition, paracrine and autocrine actions of TGF-beta have overlapping but distinct regulatory effects on hematopoietic stem/progenitor cells. Neutralization of autocrine TGF-beta has therapeutic potential.