A sticky wicket: Defining molecular functions for CD34 in hematopoietic cells

Exp Hematol. 2020 Jun:86:1-14. doi: 10.1016/j.exphem.2020.05.004. Epub 2020 May 16.


The CD34 cell surface antigen is widely expressed in tissues on cells with progenitor-like properties and on mature vascular endothelia. In adult human bone marrow, CD34 marks hematopoietic stem and progenitor cells (HSPCs) starting from the bulk of hematopoietic stem cells with long-term repopulating potential (LT-HSCs) throughout expansion and differentiation of oligopotent and unipotent progenitors. CD34 protein surface expression is typically lost as cells mature into terminal effectors. Because of this expression pattern of HSPCs, CD34 has had a central role in the evaluation or selection of donor graft tissue in HSC transplant (HSCT). Given its clinical importance, it is surprising that the biological functions of CD34 are still poorly understood. This enigma is due, in part, to CD34's context-specific role as both a pro-adhesive and anti-adhesive molecule and its potential functional redundancy with other sialomucins. Moreover, there are also critical differences in the regulation of CD34 expression on HSPCs in humans and experimental mice. In this review, we highlight some of the more well-defined functions of CD34 in HSPCs with a focus on proposed functions most relevant to HSCT biology.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Antigens, CD34 / metabolism*
  • Bone Marrow / metabolism
  • Cell Differentiation*
  • Gene Expression Regulation
  • Hematopoietic Stem Cell Transplantation
  • Hematopoietic Stem Cells / cytology
  • Hematopoietic Stem Cells / metabolism*
  • Humans
  • Mice


  • Antigens, CD34