Submitted February 23, 2007
Accepted October 24, 2007
Clinical stem cell sources contain CD8+CD3+ T cell receptor-negative cells that facilitate bone marrow repopulation with hematopoietic stem cells
Stephanie Bridenbaugh, Linda Kenins, Emilie Bouliong-Pillai, Christian P Kalberer, Elena Shklovskaya, Alois Gratwohl, and Aleksandra Wodnar-Filipowicz*
Experimental Hematology, Department of Research, University Hospital Basel, Basel, Switzerland
Clinical Hematology, University Hospital Basel, Basel, Switzerland
* Corresponding author; email: aleksandra.wodnar-filipowicz{at}unibas.ch.
Clinical observations in patients undergoing bone marrow transplantation implicate the involvement of CD8+ cells in promoting the stem cell engraftment process. These findings are supported by mouse transplant studies which attributed the engraftment-facilitating function to sub-populations of murine CD8+ cells, but the analogous cells in humans have not been identified. Here, we report that clinical stem cell grafts contain a population of CD8
+CD3
+ T cell receptor-negative cells with an engraftment facilitating function, named candidate facilitating cells (cFC). Purified cFC augmented human hematopoiesis in NOD/SCID mice receiving suboptimal doses of human CD34+ cells. In vitro, cFC co-cultured with CD34+ cells increased hematopoietic colony formation, suggesting a direct effect on clonogenic precursors. These results provide evidence for the existence of rare human CD8+CD3+TCR- cells with engraftment facilitating properties, the adoptive transfer of which could improve the therapeutic outcome of stem cell transplantation.
