Umbilical cord blood is a traditional and convenient source of cells for hematopoietic stem cell transplantation. Thymic regulatory T cells (Tregs) are also present in cord blood, and there is growing interest in the use of autologous Tregs to provide a low-risk, fully human leukocyte antigen (HLA)-matched cell product for treating autoimmune diseases, such as type 1 diabetes. Here, we describe a good manufacturing practice (GMP)-compatible Treg expansion protocol using fluorescence-activated cell sorting, resulting in a mean 2,092-fold expansion of Tregs over a 16-day culture for a median yield of 1.26 × 109 Tregs from single-donor cryopreserved units. The resulting Tregs passed prior clinical trial release criteria for Treg purity and sterility, including additional rigorous assessments of FOXP3 and Helios expression and epigenetic analysis of the FOXP3 Treg-specific demethylated region (TSDR). Compared with expanded adult peripheral blood Tregs, expanded cord blood Tregs remained more naive, as assessed by continued expression of CD45RA, produced reduced IFN-γ following activation, and effectively inhibited responder T cell proliferation. Immunosequencing of the T cell receptor revealed a remarkably diverse receptor repertoire within cord blood Tregs that was maintained following in vitro expansion. These data support the feasibility of generating GMP-compliant Tregs from cord blood for adoptive cell transfer therapies and highlight potential advantages in terms of safety, phenotypic stability, autoantigen specificity, and tissue distribution.

Poor peripheral blood stem cell (PBSC) mobilization predicts worse outcome for myeloma and lymphoma patients post autologous stem cell transplant (ASCT). We hypothesize that PBSC harvest using plerixafor and G-CSF in poor mobilizers may improve long-term outcome. We retrospectively analyzed the data on patients who had second PBSC mobilization using plerixafor and G-CSF as a rescue. Nine lymphoma and 8 multiple myeloma (MM) patients received the drug. A control group of 25 MM and lymphoma patients who were good mobilizers with G-CSF only was used for comparison. Sixteen of the 17 poor mobilizers proceeded to ASCT, and one MM patient had tandem transplants. Length of hospital stay, infection incidence, granulocyte engraftment, and long-term hematopoietic recovery were not significantly different between the two groups. In conclusion, all poor mobilizers were able to obtain adequate stem cells transplant dose and had similar transplant course and long-term outcome to that of the control good mobilizers group.

Background Relapsing disease is a major challenge after hematopoietic cell transplant for hematological malignancies. Myxoma virus (MYXV) is an oncolytic virus that can target and eliminate contaminating cancer cells from auto-transplant grafts. The aims of this study were to examine the impact of MYXV on normal hematopoietic stem and progenitor cells, and define the optimal treatment conditions for ex vivo virotherapy. Methods Bone marrow (BM) and mobilized peripheral blood stem cells (mPBSCs) from patients with hematological malignancies were treated with MYXV at various time, temperature and incubation media conditions. Treated BM cells from healthy normal donors were evaluated by flow cytometry for MYXV infection, LTC-IC assay, and CFC assay. Results MYXV initiated infection in up to 45% of antigen presenting monocytes, B cells and natural killer cells; however, these infections were uniformly aborted in > 95% of all cells. Fresh graft sources showed higher levels of MYXV infection initiation than cryopreserved specimens but all cases, less than 10% of CD34+ cells could be infected after ex vivo MYXV treatment. MYXV did not impair LTC-IC colony numbers compared to mock treatment. CFC colony types and numbers were also not impaired by MYXV treatment. MYXV incubation time, temperature or culture media did not significantly change percentage of infected cells, LTC-IC colony formation or CFC colony formation. Conclusions Human hematopoietic cells are non-permissive for MYXV. Human hematopoietic stem and progenitor cells were not infected and thus unaffected by MYXV ex vivo treatment.

The high variability and low counts found in AutoUCB banking suggest that further standardization of characterization, collection, and processing procedures is needed.