Work

Ex Vivo Treatment of Hematopoietic Stem Cells With 16,16-Dimethyl Prostaglandin E2 (FT1050) Improves Engraftment and Hematopoietic Reconstitution

Year: 2011

Type: article

Abstract: Through an in vivo zebrafish screen for modulators of hematopoietic stem cell (HSC) development, a small molecule, 16,16-dimethyl prostaglandin E2 (FT1050) was identified (North, 2007). FT1050 was shown to enhance the engraftment potential of HSCs from murine bone marrow (mBM) or human umbilical cord blood (hCB) in murine engraftment models through an increase in proliferation, survival, migration and homing after a brief (1 to 2 hr) ex vivo treatment (North, 2007; North, 2009; Hoggatt, 2009; North, Goessling, Zon, unpublished data). We further optimized the ex vivo hCB incubation protocol using whole genome expression arrays and determined that HSC-containing cell products should be incubated with 10μM FT1050 for 2 hrs at 37°C to obtain the optimal response. In addition, we observed that FT1050 induces similar gene expression changes in hBM- and mobilized peripheral blood-derived CD34+ cells. Subsequent functional studies demonstrated that in keeping with increases of up to 18-fold in CXCR4 gene expression, cell surface CXCR4 protein expression was also significantly increased. One hour after treatment with10μM FT1050 for 2 hrs at 37°C, 48±1.9% of CB CD34+ cells expressed CXCR4 compared to 3.5±0.01% in DMSO control (p < 0.05). In vivo CFU-S12 analysis showed that treatment of mBM cells with 10μM FT1050 for 2 hrs at 37°C resulted in greater proliferation with a statistically significant increase in colony formation, 11.5±1.4, compared to 4±0.8 colonies with DMSO control (p < 0.001). This short-term ex vivo incubation protocol, 10μM FT1050 for 2 hrs at 37°C, has been introduced into an ongoing Phase Ib clinical trial in adults with hematologic malignancies receiving a nonmyeloablative conditioning (melphalan, fludarabine and ATG) followed by double hCB transplantation, in which one of the two hCBs is incubated with FT1050 prior to infusion. The primary objective of the study is to determine the safety of FT1050 treatment of hCB. Preliminary data demonstrate that this ex vivo incubation can be reliably performed at the clinical site on the day of infusion with good cell recovery and viability. 11 subjects with a median age of 44 years have been accrued to date, of which two have been treated using the optimized ex vivo incubation protocol. 10 of 11 patients have achieved an ANC > 500 before Day 42. Transplant related mortality has been low with one death at Day 53 from respiratory failure. 9 patients are alive, of which 7 are disease-free. Accrual is ongoing.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.bbmt.2010.12.224