Submitted January 8, 2009
Accepted April 1, 2009
Probing the mitotic history and developmental
stage of hematopoietic cells using single telomere
length analysis (STELA)
Mark Hills, Kai Lucke, Elizabeth A. Chavez, Connie J. Eaves, and Peter M. Lansdorp*
Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
* Corresponding author; email: plansdor{at}bccrc.ca.
In most human somatic cells, telomeres shorten as a function of DNA replication. Telomere length is therefore an indirect measure of the replicative history of cells. We measured the telomere lengths at XpYp chromosomes in purified human hematopoietic populations enriched for stem cells (Lin-CD34+CD38-Rho-) and successively more mature cells. The average telomere length showed expected length changes, pointing to the utility of this method for classifying novel differentiation markers. Interestingly, the frequency of abruptly shortened telomeres increased in terminally differentiated adult populations, suggesting that damage to telomeric DNA occurs or is not repaired upon hematopoietic differentiation. When Lin-CD34+CD38-Rho- cord blood cells were transplanted into immunodeficient mice, the telomeres of the most primitive regenerated human hematopoietic cells lost approximately 3 kb, indicative of over 30 cell divisions. Further losses in differentiating cells were similar to those observed in pre-transplant cell populations. These results indicate extensive self-renewal divisions of human hematopoietic stem cells is the primary cause of telomere erosion upon transplantation rather than added cell divisions in downstream progenitors.
