Expression of Thy-1 on human hematopoietic progenitor cells

Area of Science:

• Immunology
• Hematology
• Stem Cell Biology

Background:

• Thy-1 is a cell surface glycoprotein found on various cell types, including some hematopoietic cells.
• Previous studies suggested Thy-1 expression on primitive hematopoietic cells, but its precise role and expression patterns in human samples remained unclear.

Purpose of the Study:

• To characterize Thy-1 expression on human hematopoietic stem and progenitor cells from fetal liver, cord blood, and bone marrow.
• To investigate the functional significance of Thy-1 expression on CD34+ cells in hematopoiesis.

Main Methods:

• Utilized a novel anti-Thy-1 antibody (5E10) for immunofluorescence staining and immunoprecipitation.
• Performed multi-color flow cytometry to analyze Thy-1 expression in conjunction with CD34, CD38, CD45RO, CD45RA, CD71, and c-kit.
• Sorted Thy-1+ and Thy-1- CD34+ cells and assessed their clonogenic and long-term culture initiating cell potential.

Main Results:

• Thy-1 expression was detected on a small subset (1-4%) of hematopoietic cells in fetal liver, cord blood, and bone marrow.
• Thy-1+ cells were predominantly found within the CD34+ population (approximately 25%), characterized by specific marker profiles (CD38lo, CD45RO+, CD45RA-, CD71lo, c-kit(lo)).
• The majority of long-term culture initiating cells (LTCI-Cs) capable of myeloid colony formation were enriched in the Thy-1+ CD34+ fraction, while clonogenic cells were mainly in the Thy-1- CD34+ fraction.

Conclusions:

• The novel anti-Thy-1 antibody 5E10 effectively identifies a distinct population of primitive human hematopoietic cells.
• Thy-1 expression on CD34+ cells correlates with the capacity for sustained myeloid hematopoiesis.
• Thy-1 is a valuable marker for further investigation into the biology and purification of human stem cells.