Submitted June 20, 2006
Accepted August 20, 2006
Low Rhodamine123 retention identifies long-term human hematopoietic stem cells within the Lin-CD34+CD38- population
Joby L McKenzie, Katsuto Takenaka, Olga I Gan, Monica Doedens, and John E Dick*
University Health Network, University of Toronto, Toronto, ON, Canada
Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
* Corresponding author; email: jdick{at}uhnres.utoronto.ca.
Progress to uncover the molecular and cellular regulators that govern human hematopoietic stem cell (HSC) fate has been impeded by an inability to obtain highly purified fractions of HSC. We report that the Rhodamine (Rho) 123 dye effluxing fraction of the Lin-CD34+CD38- population contains SCID-repopulating cells (SRC) capable of long-term repopulation in primary NOD/SCID mice. Purification based on Rho uptake led to a 4-fold enrichment of SRC in the Lin-CD34+CD38- fraction, with a frequency of 1 SRC in 30 Lin-CD34+CD38-Rholo cells. The Lin-CD34+CD38-Rholo fraction also possesses long-term self-renewal capacity as measured by serial transplantation totaling over 20 weeks. We conclude that Rho dye efflux provides an additional means of purifying human HSC in the quest to achieve homogeneous populations of primitive cells for both experimental and therapeutic applications.
