Use of Genome-Wide Expression Analysis to Optimize An Ex Vivo clinical Protocol for 16,16-Dimethyl Prostaglandin E2 Enhancement of Umbilical Cord Blood In Hematopoietic Stem Cell Transplantation.

Abstract 1451

A systematic investigation was performed to optimize the treatment protocol for ex vivo incubation of human hematopoietic stem cells (HSCs) with 16,16-dimethyl prostaglandin E2 (FT1050) prior to transplantation. This protocol is part of an ongoing Phase Ib clinical trial of FT1050-enhanced double cord blood (CB) transplantation after reduced intensity conditioning. FT1050 has been previously shown in vertebrate models to improve the engraftment potential of HSCs from bone marrow (BM) and CB after a brief ex vivo treatment. In these models, treatment of BM or CB with FT1050 was performed for 1 to 2 hours at 4 °C, followed by a wash and subsequent cell infusion into the recipient (North et al. Nature 2007, Hoggatt et al. Blood 2009). Several groups have demonstrated that under these conditions, FT1050-treated cells have an engraftment advantage over vehicle treated cells. The objective of the current investigation was to identify a set of conditions that maximizes the biologic activity of FT1050. Genome-wide expression analysis and cAMP assays were used to optimize the ex vivo FT1050 treatment protocol with respect to concentration, time and temperature. Using this approach, hundreds of up- and down-regulated genes were identified in FT1050-treated CD34+ cells. These signature genes include upregulation of CXCR4, a known mediator of HSC homing via SDF-1a, and CREB, a key gene involved in cAMP signaling. Results from these experiments demonstrated that FT1050 concentrations above 10 μM did not result in increased levels of biologic activity. In terms of duration of incubation, cAMP activity reached maximal levels within 30 minutes of exposure while a 2 hour treatment period was necessary to maximize the changes in gene expression. Finally, the biologic activity of FT1050 was highly sensitive to temperature, with treatment of cells at 37 °C yielding larger changes in cAMP production and gene expression as compared to incubation of cells at 25 °C and 4 °C. The biological effects of FT1050 on subsets of CD34+ cells isolated from CB were also determined. Interestingly, the stem/progenitor subsets of CD34+ cells (Lin-CD34+CD38-CD90+CD45RA-, Lin-CD34+CD38-CD90-CD45RA- and Lin-CD34+) had a greater response to FT1050 relative to the lineage positive cells. The different conditions were also evaluated using CFU-C and 7-AAD assays. No evidence of adverse effects were observed. Based upon these findings, the ongoing clinical trial incorporates the optimized FT1050 ex vivo treatment protocol (10 μM for 120 minutes at 37 °C).