Mesenchymal stem/stromal cells (MSCs) are widely studied by both academia and industry for a broad array of clinical indications. The collective body of data provides compelling evidence of the clinical safety of MSC therapy. However, generally accepted proof of therapeutic efficacy has not yet been reported. In an effort to generate a more effective therapeutic cell product, investigators are focused on modifying MSC processing protocols to enhance the intrinsic biologic activity. Here, we report a Good Manufacturing Practice-compliant two-step MSC manufacturing protocol to generate MSCs or interferon c (IFNc) primed MSCs which allows freshly expanded cells to be infused in patients on a predetermined schedule. This protocol eliminates the need to infuse cryopreserved, just thawed cells which may reduce the immune modulatory activity. Moreover, using (IFNc) as a prototypic cytokine, we demonstrate the feasibility of priming the cells with any biologic agent. We then characterized MSCs and IFNc primed MSCs prepared with our protocol, by karyotype, in vitro potential for malignant transformation, biodistribution, effect on engraftment of transplanted hematopoietic cells, and in vivo toxicity in immune deficient mice including a complete post-mortem examination. We found no evidence of toxicity attributable to the MSC or IFNc primed MSCs. Our data suggest that the clinical risk of infusing MSCs or IFNc primed MSCs produced by our two-step protocol is not greater than MSCs currently in practice. While actual proof of safety requires phase I clinical trials, our data support the use of either cell product in new clinical studies. STEM CELLS TRANSLATIONAL MEDICINE 2017;6:1868-1879 SIGNIFICANCE STATEMENTMesenchymal stem/stromal cells (MSCs) are one of the most widely studied cells for the development of cellular therapies. While these cells are unequivocally safe to use in humans, the efficacy of MSCs to treat diseases has not been established. Hence, current efforts are focused on developing the technology to enhance the efficacy of MSCs. Here, we report a novel strategy to prepare MSCs that would mitigate the potential reduction of cell potency observed when infusing freshly thawed, cryopreserved cells. Additionally, we show extensive preclinical data to support the safety of interferon g-primed MSCs, which are designed to enhance the immune modulatory potency of MSCs.

CARMIL2 deficiency is a rare combined immunodeficiency (CID) characterized by defective CD28-mediated T cell co-stimulation, altered cytoskeletal dynamics, and susceptibility to Epstein Barr Virus smooth muscle tumors (EBV-SMTs). Case reports associated with EBV-SMTs are limited. We describe herein a novel homozygous CARMIL2 variant (c.1364_1393del) in two Saudi Arabian male siblings born to consanguineous parents who developed EBV-SMTs. CARMIL2 protein expression was significantly reduced in CD4+ T cells and CD8+ T cells. T cell proliferation on stimulation with soluble (s) anti-CD3 or (s) anti-CD3 plus anti-CD28 antibodies was close to absent in the proband, confirming altered CD28-mediated co-signaling. CD28 expression was substantially reduced in the proband's T cells, and was diminished to a lesser degree in the T cells of the younger sibling, who has a milder clinical phenotype. Defects in both T and B cell compartments were observed, including absent central memory CD8+ T cells, and decreased frequencies of total and class-switched memory B cells. FOXP3+ regulatory T cells (Treg) were also quantitatively decreased, and furthermore CD25 expression within the Treg subset was substantially reduced. These data confirm the pathogenicity of this novel loss-of-function (LOF) variant in CARMIL2 and expand the genotypic and phenotypic spectrum of CIDs associated with EBV-SMTs.

Advances in allogeneic hematopoietic cell transplantation for sickle cell disease have improved outcomes, but there is limited analysis of healthcare utilization in this setting. We hypothesized that, compared to late transplantation, early transplantation (at age <10 years) improves outcomes and decreases healthcare utilization. We performed a retrospective study of children transplanted for sickle cell disease in the USA during 2000–2013 using two large databases. Univariate and Cox models were used to estimate associations of demographics, sickle cell disease severity, and transplant-related variables with mortality and chronic graft-versus-host disease, while Wilcoxon, Kruskal-Wallis, or linear trend tests were applied for the estimates of healthcare utilization. Among 161 patients with a 2-year overall survival rate of 90% (95% confidence interval [CI] 85–95%) mortality was significantly higher in those who underwent late transplantation versus early (hazard ratio (HR) 21, 95% CI 2.8–160.8, P=0.003) and unrelated compared to matched sibling donor transplantation (HR 5.9, 95% CI 1.7–20.2, P=0.005). Chronic graftversus host disease was significantly more frequent among those translanted late (HR 1.9, 95% CI 1.0–3.5, P=0.034) and those who received an unrelated graft (HR 2.5, 95% CI 1.2–5.4; P=0.017). Merged data for 176 patients showed that the median total adjusted transplant cost per patient was $467,747 (range: $344,029–$799,219). Healthcare utilization was lower among recipients of matched sibling donor grafts and those with low severity disease compared to those with other types of donor and disease severity types (P<0.001 and P=0.022, respectively); no association was demonstrated with late transplantation (P=0.775). Among patients with 2-year pre- and post-transplant data (n=41), early transplantation was associated with significant reductions in admissions (P<0.001), length of stay (P<0.001), and cost (P=0.008). Early transplant outcomes need to be studied prospectively in young children without severe disease and an available matched sibling to provide conclusive evidence for the superiority of this approach. Reduced post-transplant healthcare utilization inpatient care indicates that transplantation may provide a sustained decrease in healthcare costs over time.

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SummaryExtracorporeal photopheresis (ECP) is an established second line treatment option for graft-versus-host disease (GVHD) post-haematopoietic progenitor cell transplant. At our centre, the Therakos TM Cellex ® has replaced the Therakos TM UVAR-XTS TM machine for ECP since 2009. We reviewed the records of 385 procedures using the Therakos TM Cellex ® for safety and tolerability. Nine patients underwent ECP for GVHD. The median age was 13Á5 years (range 3Á7-24) and weight was 49Á2 kg (range 18Á5-86Á3). The mean duration per procedure was 106 min (range 60-205). Fifteen (3Á9%) procedures were cancelled and 10 (2Á6%) were delayed, with central venous line (CVL) issues being the most frequent problem. With the use of prophylactic tissue plasminogen activator, fewer CVL-related occlusions were observed (4Á7% vs. 2Á3%). There was one episode of a CVL-associated thrombosis and one episode of delayed bleeding. There were four episodes of viral reactivation, four CVL-associated infections (1142 catheter days) and one episode of systemic inflammatory response syndrome. No patient experienced symptomatic hypotension. This is the first report outlining the safety and tolerability of the Therakos TM Cellex ® device for ECP in children and young adults.

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The adoptive transfer of natural killer (NK) cells is an emerging therapy in the field of immuno-oncology. In the last 3 decades, NK cells have been utilized to harness the anti-tumor immune response in a wide range of malignancies, most notably with early evidence of efficacy in hematologic malignancies. NK cells are dysfunctional in patients with hematologic malignancies, and their number and function are further impaired by chemotherapy, radiation, and immunosuppressants used in initial therapy and hematopoietic stem cell transplantation. Restoring this innate immune deficit may lead to improved therapeutic outcomes. NK cell adoptive transfer has proven to be a safe in these settings, even in the setting of HLA mismatch, and a deeper understanding of NK cell biology and optimized expansion techniques have improved scalability and therapeutic efficacy. Here, we review the use of NK cell therapy in hematologic malignancies and discuss strategies to further improve the efficacy of NK cells against these diseases.

Key Points HCT prior to onset of neurologic symptoms in children with OSTM1 osteopetrosis does not halt neurologic progression.