As more efficient agents for stem cell mobilization are being developed, there is an urgent need to define which patient population might benefit from these novel drugs. For a precise and prospective definition of "poor mobilization" (PM), we have analyzed the efficiency of mobilization in patients intended to receive autologous transplantation at our center in the past 6 years. Between January 2003, and December 2008, 840 patients with the following diagnoses were scheduled to undergo leukapheresis: multiple myeloma (MM, n = 602) and non-Hodgkin lymphoma (NHL, n= 238). Most patients mobilized readily: close to 85% of the patients had a level of 20/microL to >500/microL of CD34(+) cells at the peak of stimulation. Of the 840 patients, 129 (15.3%) were considered to be PMs, defined as patients who had a peak concentration of <20/microL of CD34(+) cells upon stimulation with granulocyte-colony stimulating factor (G-CSF) subsequent to induction chemotherapy appropriate for the respective disease. Among them, 38 (4.5%) patients had CD34(+) levels between 11 and 19/microL at maximum stimulation, defined as "borderline" PM, 49 (5.8%) patients had CD34(+) levels between 6 and 10/microL, defined as "relative" PM, and 42 patients (5%) with levels of <5/microL, defined as "absolute" PM. There was no difference in the incidence of PM between patients with MM versus those with NHL. Sex, age, body weight (b.w.) and previous irradiation therapy did not make any significant difference. Only the total number of cycles of previous chemotherapy (P = .0034), and previous treatment with melphalan (Mel; P = .0078) had a significant impact on the ability to mobilize. For the good mobilizers, the median time to recovery of the white blood cells (WBCs) to 1.0/nL or more was 13 days with a range of 7 to 22 days, whereas for the PM group it was 14 days with a range of 8 to 37 days. This difference was statistically not significant. The median time to recovery of the platelets counts to an unmaintained level of >20/nL was 11 days with a range of 6 to 17 days for the good mobilizers, whereas for the PM it was 11 days with a range of 7 to 32 days. Again, this difference was not significant. The majority of the patients today intended for autologous transplantations were able to mobilize readily. As long as > or =2.0 x 10(6) of CD34(+) cells/kg b.w. have been collected, PM was not associated with inferior engraftment.

2153 Poster Board II-130 Hematopoietic progenitor and stem cells (HSC) reside in the bone marrow and have to be mobilized into the circulation prior to being collected by apheresis. The number of apheresis procedures needed and the success of transplantation are determined by the efficiency of stem cell mobilization. Between January 2004 to December 2008, 840 patients (pt) with the following diagnoses were scheduled to undergo leukapheresis for autologous transplantations: multiple myeloma (MM, n=602) and non-Hodgkin's lymphoma (NHL, n=238). Mobilization data and transplantation outcome were analyzed retrospectively. Most of the pt mobilized readily: close to 85% of the pt had a level of 20/μL to >500/μL of CD34+ cells at the peak of stimulation. Of the 840 pt, 129 (15.3%) were considered to be “Poor Mobilizers” (PM), defined as pt who had a peak concentration of <20/μL of CD34+ cells upon stimulation with G-CSF subsequent to induction chemotherapy appropriate for the respective disease. Among them, 38 (4.5%) pt had CD34+ levels of between 11-19/μL at maximum stimulation, defined as borderline PM, 49 (5.8%) pt had CD34+ levels of between 6-10/μL, defined as relative PM and 42 pt (5%) with levels of <5/μL, defined as absolute PM. We have analyzed the relationship between poor mobilizations with types of disease (MM versus NHL), sex, age, body weight, previous irradiation, number of cycles of previous combination chemotherapy, and pretreatment with melphalan. There was no difference in the incidence of PM between pt with MM versus those with NHL. Sex, age, body weight and previous irradiation therapy did not make any significant difference. Only the number of cycles of previous chemotherapy (p=0.0034), and previous treatment with melphalan (p=0.0078) had a significant impact on the ability to mobilize. Secondary strategies to mobilize HSC from the 33 who failed included: (1) Administration of another cycle of induction chemotherapy + G-CSF. The goal of harvesting 2.0 × 10exp6 CD34+ cells/kg body weight could be accomplished in 7 of 21 of these patients. (2) G-CSF alone for 4 days (up to 8 days of stimulation) after hematopoietic recovery from previous induction chemotherapy. The goal could be achieved in 2 of the 9 patients thus mobilized. (3) Plerixafor within the compassionate use program. The goal was accomplished in 7 of 8 patients within one cycle of mobilization. All 8 could be transplanted successfully. (4) Bone marrow harvest in lieu of collection of peripheral HSC in 5 patients. For the good mobilizers, the median time to recovery of the WBC to 1.0/nL or granulocyte of 0.5/nL (whichever is sooner) was 13 days with a range of 7 to 22 days, whereas for the PM group it was 14 days with a range of 8 to 37 days. This difference was statistically not significant. The median time to recovery of the platelets counts to an unmaintained level of >20/nL was 11 days with a range of 6 to 17 days for the good mobilizers, whereas for the PM it was 11 days with a range of 7 to 32 days. Again this difference was statistically not significant. The majority of the patients nowadays intended for autologous transplantations were able to mobilize readily. According to the criteria proposed in this study, 15.3% were considered to be “Poor Mobilizers”, 4.5% borderline PM, 5.8% relative PM and 5% absolute PM. No significant difference was found between patients with NHL versus MM. Sex, age, body weight and previous irradiation therapy did not make any difference. Only the number of cycles of previous chemotherapy (p=0.0034), and previous treatment with melphalan (p=0.0078) had a significant impact. Above all, as long as 2.0 × 10exp6 of CD34+ cells per kg of body weight have been collected, poor mobilization was not associated with inferior engraftment. Disclosures: No relevant conflicts of interest to declare.

Key Points• Expression of RUNX1a, an isoform of RUNX1, enhances blood cell production from human pluripotent stem cells.Advancements in human pluripotent stem cell (hPSC) research have potential to revolutionize therapeutic transplantation. It has been demonstrated that transcription factors may play key roles in regulating maintenance, expansion, and differentiation of hPSCs. In addition to its regulatory functions in hematopoiesis and blood-related disorders, the transcription factor RUNX1 is also required for the formation of definitive blood stem cells. In this study, we demonstrated that expression of endogenous RUNX1a, an isoform of RUNX1, parallels with lineage commitment and hematopoietic emergence from hPSCs, including both human embryonic stem cells and inducible pluripotent stem cells. In a defined hematopoietic differentiation system, ectopic expression of RUNX1a facilitates emergence of hematopoietic progenitor cells (HPCs) and positively regulates expression of mesoderm and hematopoietic differentiation-related factors, including Brachyury, KDR, SCL, GATA2, and PU.1. HPCs derived from RUNX1a hPSCs show enhanced expansion ability, and the ex vivo-expanded cells are capable of differentiating into multiple lineages. Expression of RUNX1a in embryoid bodies (EBs) promotes definitive hematopoiesis that generates erythrocytes with b-globin production. Moreover, HPCs generated from RUNX1a EBs possess ‡9-week repopulation ability and show multilineage hematopoietic reconstitution in vivo. Together, our results suggest that RUNX1a facilitates the process of producing therapeutic HPCs from hPSCs. (Blood. 2013;121(15):2882-2890

Surface molecular imprinting, especially on the surface of silica-modified magnetic nanoparticles, has been proposed as a promising strategy for protein recognition and separation. Inspired by the self-polymerization of dopamine, we synthesized a polydopamine-based molecular imprinted film coating on silica-Fe(3)O(4) nanoparticles for recognition and separation of bovine hemoglobin (BHb). Magnetic molecularly imprinted nanoparticles (about 860 nm) possess a core-shell structure. Magnetic molecularly imprinted nanoparticles (MMIP) show a relatively high adsorption capacity (4.65 ± 0.38 mg g(-1)) and excellent selectivity towards BHb with a separation factor of 2.19. MMIP with high saturation magnetization (10.33 emu g(-1)) makes it easy to separate the target protein from solution by an external magnetic field. After three continuous adsorption and elution processes, the adsorption capacity of MMIP remained at 4.30 mg g(-1). Our results suggest that MMIPs are suitable for the removal of high abundance of protein and the enrichment of low abundance of protein in proteomics.