Endothelial mTOR maintains hematopoiesis during aging

J Exp Med. 2020 Jun 1;217(6):e20191212. doi: 10.1084/jem.20191212.


Aging leads to a decline in hematopoietic stem and progenitor cell (HSPC) function. We recently discovered that aging of bone marrow endothelial cells (BMECs) leads to an altered crosstalk between the BMEC niche and HSPCs, which instructs young HSPCs to behave as aged HSPCs. Here, we demonstrate aging leads to a decrease in mTOR signaling within BMECs that potentially underlies the age-related impairment of their niche activity. Our findings reveal that pharmacological inhibition of mTOR using Rapamycin has deleterious effects on hematopoiesis. To formally determine whether endothelial-specific inhibition of mTOR can influence hematopoietic aging, we conditionally deleted mTOR in ECs (mTOR(ECKO)) of young mice and observed that their HSPCs displayed attributes of an aged hematopoietic system. Transcriptional profiling of HSPCs from mTOR(ECKO) mice revealed that their transcriptome resembled aged HSPCs. Notably, during serial transplantations, exposure of wild-type HSPCs to an mTOR(ECKO) microenvironment was sufficient to recapitulate aging-associated phenotypes, confirming the instructive role of EC-derived signals in governing HSPC aging.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / physiology*
  • Animals
  • Bone Marrow Cells / cytology
  • Bone Marrow Cells / metabolism
  • Cellular Microenvironment
  • Endothelial Cells / metabolism*
  • Hematopoiesis* / drug effects
  • Hematopoietic Stem Cells / cytology
  • Hematopoietic Stem Cells / drug effects
  • Hematopoietic Stem Cells / metabolism
  • Mechanistic Target of Rapamycin Complex 1 / metabolism
  • Mechanistic Target of Rapamycin Complex 2 / metabolism
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Signal Transduction
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases / metabolism*
  • Transcription, Genetic


  • Mechanistic Target of Rapamycin Complex 1
  • Mechanistic Target of Rapamycin Complex 2
  • TOR Serine-Threonine Kinases
  • Sirolimus