Assessment of Ex Vivo Prostaglandin pathway activation in HSCs

Transplantation with low numbers of hematopoietic stem cells (HSCs), found in many of the publically accessible cryopreserved umbilical cord blood (UCB) units, leads to delayed time to engraftment, high graft failure rates, and early mortality in many patients. A chemical screen in zebrafish identified the prostaglandin compound, 16,16 dimethyl prostaglandin E2 (dmPGE2), to be a critical regulator of hematopoietic stem cell homeostasis. We hypothesized that an ex vivo modulation with dmPGE2 prior to transplantation would lead to enhanced engraftment by increasing the effective dose of hematopoietic stem cells (HSCs) in cord blood. A phase I trial of reduced-intensity double UCB transplantation was performed to evaluate safety, rates of engraftment and fractional chimerism of dmPGE2 enhanced UCB units. To explore potential causes of the lack of enhanced efficacy in the first cohort, we characterized HSCs to determine whether the prostaglandin pathway was being activated under the ex vivo incubation conditions (4C, 10M dmPGE2, 60 minutes). Incubation conditions were identified (37C, 10M dmPGE2, 120 minutes) that maximize the activation of the prostaglandin pathway by dmPGE2 in human CD34+ cells.

20

Cutler C, Multani P, Robbins D, Kim HT, Le T, Hoggatt J, Pelus LM, Desponts C, Chen YB, Rezner B, Armand P, Koreth J, Glotzbecker B, Ho VT, Alyea E, Isom M, Kao G, Armant M, Silberstein L, Hu P, Soiffer RJ, Scadden DT, Ritz J, Goessling W, North TE, Mendlein J, Ballen K, Zon LI, Antin JH, Shoemaker DD