Acellular Bone Marrow Extracts Significantly Enhance Engraftment Levels of Human Hematopoietic Stem Cells in Mouse Xeno-Transplantation Models

Hematopoietic stem cells (HSC) derived from cord blood (CB), bone marrow (BM), or mobilized peripheral blood (PBSC) can differentiate into multiple lineages such as lymphoid, myeloid, erythroid cells and platelets. The local microenvironment is critical to the differentiation of HSCs and to the preservation of their phenotype in vivo. This microenvironment comprises a physical support supplied by the organ matrix as well as tissue specific cytokines, chemokines and growth factors. We investigated the effects of acellular bovine bone marrow extracts (BME) on HSC in vitro and in vivo. We observed a significant increase in the number of myeloid and erythroid colonies in CB mononuclear cells (MNC) or CB CD34+ cells cultured in methylcellulose media supplemented with BME. Similarly, in xeno-transplantation experiments, pretreatment with BME during ex-vivo culture of HSCs induced a significant increase in HSC engraftment in vivo. Indeed, we observed both an increase in the number of differentiated myeloid, lymphoid and erythroid cells and an acceleration of engraftment. These results were obtained using CB MNCs, BM MNCs or CD34+ cells, transplanted in immuno-compromised mice (NOD/SCID or NSG). These findings establish the basis for exploring the use of BME in the expansion of CB HSC prior to HSC Transplantation. This study stresses the importance of the mechanical structure and soluble mediators present in the surrounding niche for the proper activity and differentiation of stem cells

AML-loaded DC generate Th1-type cellular immune responses in vitro

Background The generation of AML-specific T-lymphocyte responses by leukemia-derived DC has been documented by multiple investigators and is being pursued clinically. An obstacle to widespread use of this strategy is that it has not been possible to generate leukemic DC from all patients, and an alternative approach is needed if the majority of leukemia patients are to receive therapeutic vaccination in conjunction with other treatment protocols. Methods In the present study, we generated DC from CD14-selected monocytes isolated from healthy donor PBPC and loaded them with a total cell lysate from AML patient blasts. Results Immature in vitro-derived DC exhibited robust phagocytic activity, and mature DC demonstrated high expression of CD80, CD83, CD86 and the chemokine receptor CCR7, important for DC migration to local lymph nodes. Mature, Ag-loaded DC were used as APC for leukemia-specific cytotoxic T-lymphocyte (CTL) induction and demonstrated cytotoxic activity against leukemic targets. CTL lysis was Ag-specific, with killing of both allogeneic leukemic blasts and autologous DC loaded with allogeneic AML lysate. HLA-matched controls were not lysed in our system. Discussion These data support further research into the use of this strategy as an alternative approach to leukemia-derived DC vaccination

Progress toward curing HIV infection with hematopoietic cell transplantation

Lawrence D Petz,1 John C Burnett,2 Haitang Li,3 Shirley Li,3 Richard Tonai,1 Milena Bakalinskaya,4 Elizabeth J Shpall,5 Sue Armitage,6 Joanne Kurtzberg,7 Donna M Regan,8 Pamela Clark,9 Sergio Querol,10 Jonathan A Gutman,11 Stephen R Spellman,12 Loren Gragert,13 John J Rossi2 1StemCyte International Cord Blood Center, Baldwin Park, CA, USA; 2Department of Molecular and Cellular Biology, Irell and Manella Graduate School of Biological Sciences, 3Department of Molecular and Cellular Biology, Beckman Research Institute, City of Hope, Duarte, CA, USA; 4CCR5-Δ32/Δ32 Research Department, StemCyte International Cord Blood Center, Baldwin Park, CA, USA; 5Department of Stem Cell Transplantation, University of Texas MD Anderson Cancer Center, Houston, TX, USA; 6MD Anderson Cord Blood Bank, Department of Stem Cell Transplantation, University of Texas MD Anderson Cancer Center, Houston, TX, USA; 7Carolinas Cord Blood Bank, Duke University Medical Center, Durham, NC, USA; 8St Louis Cord Blood Bank, SSM Cardinal Glennon Children's Medical Center, St Louis, MO, USA; 9Enhance Quality Consulting Inc., Oviedo, FL, USA; 10Cell Therapy Service and Cord Blood Bank, Banc de Sang i Teixits, Barcelona, Spain; 11BMT/Hematologic Malignancies, University of Colorado, Aurora, CO, USA; 12Immunobiology and Observational Research, CIBMTR, Minneapolis, MN, USA; 13National Marrow Donor Program/Be The Match, Minneapolis, MN, USA Abstract: HIV-1 infection afflicts more than 35 million people worldwide, according to 2014 estimates from the World Health Organization. For those individuals who have access to antiretroviral therapy, these drugs can effectively suppress, but not cure, HIV-1 infection. Indeed, the only documented case for an HIV/AIDS cure was a patient with HIV-1 and acute myeloid leukemia who received allogeneic hematopoietic cell transplantation (HCT) from a graft that carried the HIV-resistant CCR5-Δ32/Δ32 mutation. Other attempts to establish a cure for HIV/AIDS using HCT in patients with HIV-1 and malignancy have yielded mixed results, as encouraging evidence for virus eradication in a few cases has been offset by poor clinical outcomes due to the underlying cancer or other complications. Such clinical strategies have relied on HIV-resistant hematopoietic stem and progenitor cells that harbor the natural CCR5-Δ32/Δ32 mutation or that have been genetically modified for HIV-resistance. Nevertheless, HCT with HIV-resistant cord blood remains a promising option, particularly with inventories of CCR5-Δ32/Δ32 units or with genetically modified, human leukocyte antigen-matched cord blood. Keywords: curing HIV infection, hematopoietic cell transplantation, genetic modification of stem cells, CCR5 mutation, CCR5-Δ32/Δ32 cord blood inventor

Ex vivo expanded umbilical cord blood T cells maintain naive phenotype and TCR diversity

Background Umbilical cord blood (CB) is a promising source of hematopoietic stem cells for allogeneic transplantation. However, delayed engraftment and impaired immune reconstitution remain major limitations. Enrichment of donor grafts with CB T cells expanded ex vivo might facilitate improved T-cell immune reconstitution post-transplant. We hypothesized that CB T cells could be expanded using paramagnetic microbeads covalently linked to anti-CD3 and anti-CD28 Ab. Methods CB units were divided into three fractions: (1) cells cultured without beads, (2) cells cultured with beads and (3) cells cultured with beads following CD3+ magnetic enrichment. All fractions were cultured for 14 days in the presence of IL-2 (200 IU/mL). Results A mean 100-fold expansion (range 49-154) of total nucleated cells was observed in the CD3+ magnetically enriched fraction. Following expansion, CB T cells retained a naive and/or central memory phenotype and contained a polyclonal TCR diversity demonstrated by spectratyping. Discussion Our data provide evidence that naive and diverse CB T cells may be expanded ex vivo and warrant additional studies in the setting of human CB transplantation