Because of its potent immunomodulatory effect, an infusion of donor mononuclear early apoptotic cells (ApoCell) was tested in addition to cyclosporine and methotrexate as prophylaxis for acute graft-versus-host disease (GVHD) after HLA-matched myeloablative allogeneic hematopoietic stem cell transplantation (HSCT) from a related donor. In a phase I/IIa clinical trial, we treated 13 patients (median age, 37 years; range, 20 to 59 years) with hematologic malignancies: 7 patients with acute lymphoblastic leukemia, 5 patients with acute myeloid leukemia, and 1 patient with chronic myeloid leukemia, who received conventional myeloablative conditioning, with 35, 70, 140, or 210 × 10(6) cell/kg of donor ApoCell, on day -1 of transplantation. Engraftment was successful in all patients with median time to neutrophil recovery of 13 days (range, 11 to 19), and platelet recovery of 15 days (range, 11 to 59). Serious adverse effects were reported on 10 occasions in the trial, all of which were considered unrelated (n = 7) or unlikely to be related (n = 3) to ApoCell infusion. The nonrelapse mortality at day 100 and 180 after transplantation was 7.7% and the overall survival at 100 and 180 days after transplantation was 92% and 85%, respectively. All ApoCell preparations showed an in vitro significant tolerogenic effect upon interaction with dendritic cells. The overall incidence of acute grades II to IV GVHD was 23%, whereas among those receiving the 2 higher doses (n = 6), the rate was 0%. These results suggest that a single infusion of donor ApoCell in HLA-matched allogeneic HSCT is a safe and potentially effective prophylaxis for acute GVHD occurring after myeloablative conditioning. No dose limiting toxicity was observed. (Clinicaltrials.gov no. NCT00524784).

Eculizumab was safely administered to these patients. Marked clinical improvement suggests that eculizumab may be a life-saving treatment for patients with acute predominantly motor, demyelinating neuropathy with conduction block, and secondary axonal damage attributed to primary p.Cys89Tyr mutation in the CD59 gene. Ann Neurol 2016;80:708-717.

As they undergo phagocytosis, most early apoptotic cells negatively regulate proinflammatory signaling and were suggested as a major mechanism in the resolution of inflammation. The dextran sulfate sodium model is generally viewed as an epithelial damage model suited to investigate innate immune responses. Macrophages primed with LPS and subsequently exposed to DSS secrete high levels of IL-1β in an NLRP3-, ASC-, and caspase-1-dependent manner. The aim of this research was to test the therapeutic effect of a single dose of apoptotic cells in a DSS-colitis model and to explore possible mechanisms. Primary peritoneal macrophages, the DSS mice model, and Nlrp3-deficient mice, were used to assess the effect apoptotic cells on colitis. Immunohistochemistry, flow-cytometer, and western blots helped to explore the effect and mechanisms. Using a variety of NLRP3 triggering mechanisms, we show that apoptotic cells negatively regulate NF-κB and NLRP3 activation in primary peritoneal macrophages, at pre- and post-transcription levels, via inhibition of reactive oxygen species, lysosomal stabilization, and blocking K+ efflux. This property of apoptotic cells is demonstrated in a dramatic clinical, histological, and immunological amelioration of DSS colitis in Balb/c and B6 mice following a single administration of apoptotic cells.

To reach the lymphatics, migrating dendritic cells (DCs) need to interact with the extracellular matrix (ECM). Heparanase, a mammalian endo-β-D-glucuronidase, specifically degrades heparan sulfate proteoglycans ubiquitously associated with the cell surface and ECM. The role of heparanase in the physiology of bone marrow-derived DCs was studied in mutant heparanase knock-out (Hpse-KO) mice. Immature DCs from Hpse-KO mice exhibited a more mature phenotype; however their transmigration was significantly delayed, but not completely abolished, most probably due to the observed upregulation of MMP-14 and CCR7. Despite their mature phenotype, uptake of beads was comparable and uptake of apoptotic cells was more efficient in DCs from Hpse-KO mice. Heparanase is an important enzyme for DC transmigration. Together with CCR7 and its ligands, and probably MMP-14, heparanase controls DC trafficking.

4176 Because of its potent immunomodulatory effect together with presumably high safety profile, apoptotic cells infusion (ApoCell) was tested in addition to cyclosporine and methotrexate, as prophylaxis of graft-versus-host disease (GVHD) in HLA-matched myeloablative allogeneic bone marrow transplantation (alloBMT) from a related donor. We conducted a phase I//IIa clinical trial where we treated 13 patients (median age, 37 years; range, 20–59 years) with advanced hematologic malignancies (7 patients with ALL, 5 patients with AML (4 patients with MDS that transformed to AML and one patient with AML de novo), and 1 patient with CML that received conventional myeloablation with 35, or 70, or 140, or 210×106 cell/kg of donor ApoCell, on day -1 of transplantation. Ten serious adverse effects were reported with all being not related (seven) or unlikely to be related (3) to ApoCell infusion. Out of hundreds adverse effects, only three were reported as possibly related to ApoCell infusion (with no definite or probable adverse effects). The non-relapse mortality at day 100 and 180 after transplantation was the same, 7.7%. The overall survival at 100 and 180 days after transplantation was 92% and 85%, respectively. The incidences of acute grades II through IV GVHD for all 13 patients and for the two higher doses were 23% and 0% (six patients), respectively. Biomarker ratio levels including tumor necrosis factor receptor I (TNFR1), hepatocyte growth factor (HGF), interleukin 2 receptor alpha (IL-2Ra), and interleukin 7 (IL-7), supported the clinical data. These results suggest that single-infusion high-dose donor early apoptotic cells in HLA-matched myeloablative alloBMT is a safe and potentially effective single-agent prophylaxis of acute GVHD occurring after myeloablative conditioning (clinicaltrials.gov no. NCT00524784). Disclosures: Mevorach: Enlivex: Consultancy, Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Reiner:Enlivex: Employment.