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Treatment of severe aplastic anemia has improved significantly over the past 4 decades. This review will summarize the key areas of progress in the use of allogeneic hematopoietic cell transplantation and nontransplant immunosuppressive therapy (IST) for the treatment of aplastic anemia and then summarize the recommendations for first-line treatment. Based on recent data, we argue that guidelines for the initial treatment of patients with newly diagnosed severe aplastic anemia require revision. At the time of diagnosis, before beginning treatment, HLA typing should be done to identify a marrow donor among family members or in the unrelated donor registries, and a marrow transplant should be considered first-line therapy. The priority order of donor source for bone marrow transplantation is: (1) HLA-identical sibling, (2) HLA-matched unrelated donor, and (3) HLA-haploidentical donor if an HLA-matched unrelated donor is not rapidly available. Each of these donor marrow sources may be preferable to nontransplant IST. We make this recommendation because of the long-term persistent risk for disease relapse and secondary myelodysplastic syndrome or acute myeloid leukemia with the use of nontransplant IST for patients with aplastic anemia. In contrast, marrow transplantation is associated with high cure rates of aplastic anemia and a relatively low risk for graft-versus-host disease, with many patients now living for decades without the risk for disease recurrence or the development of clonal disorders. Implementation of this first-line treatment strategy will provide patients with severe aplastic anemia the best chance of long-term disease-free survival., (© 2018 by The American Society of Hematology.)

Background: Allogeneic hematopoietic cell transplantation provides a reliable method for inducing tolerance toward solid organ grafts. However, this procedure can result in graft-versus-host disease, thereby limiting its application. Here, we test the hypothesis that mixed chimerism can be intentionally reverted to host hematopoiesis without rejection of a kidney graft., Methods: Recipient dogs were given 2-Gy total-body irradiation (TBI) before and a short course of immunosuppression after marrow infusion from dog leukocyte antigen-identical littermates. All dogs achieved stable mixed chimerism. After a mean of 20 weeks, one cohort of dogs received kidney transplants from their respective marrow donors. Subsequently, recipients were reconditioned with 2-Gy TBI and given autologous granulocyte colony-stimulating factor-mobilized leukocytes (recipient leukocyte infusion [RLI]) that had been collected before marrow transplantation., Results: Dogs receiving a second TBI and RLI without a kidney transplant rejected their donor hematopoietic graft within 3 weeks. Dogs that received kidney grafts, followed by a second TBI and RLI, rejected their marrow graft without rejecting their transplanted kidneys for periods greater than 1 year., Conclusion: Mixed chimerism may be clinically reverted to 100% recipient without rejection of a kidney allograft. This finding may have application toward minimizing the risk of graft-versus-host disease in solid organ transplantation patients given hematopoietic cell transplantation from human leukocyte antigen-identical donors.

Mesenchymal stromal cells (MSCs) have been shown to have immunosuppressive effects in vitro. To test the hypothesis that these effects can be harnessed to prevent graft-versus-host disease (GVHD) and graft rejection after hematopoietic cell transplantation (HCT), we administered a combination of 3 different immortalized marrow-derived MSC lines (15-30 × 10⁶ MSCs/kg/day, 2-5 times/week) or third-party primary MSC (1.0 × 10⁶ MSCs/kg/day, 3 times/week) to canine recipients (n = 15) of dog leukocyte antigen-haploidentical marrow grafts prepared with 9.2 Gy of total body irradiation. Additional pharmacological immunosuppression was not given after HCT. Before their in vivo use, the MSC products were shown to suppress alloantigen-induced T cell proliferation in a dose-dependent, major histocompatibility complex-unrestricted, and cell contact-independent fashion in vitro. Among 14 evaluable dogs, 7 (50%) rejected their grafts and 7 engrafted, with ensuing rapidly fatal acute GVHD (50%). These observations were not statistically different from outcomes obtained with historical controls (n = 11) not given MSC infusions (P = .69). Thus, survival curves for MSC-treated dogs and controls were virtually superimposable (median survival, 18 vs 15 days, respectively). Finally, outcomes of dogs given primary MSCs (n = 3) did not appear to be different from those given clonal MSCs (n = 12). In conclusion, our data fail to demonstrate MSC-mediated protection against GVHD and allograft rejection in this model., (Copyright © 2011 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Antibiotic and antifungal agents used in supportive care regimens for bone marrow transplantation recipients contribute to a significant dose-modifying effect of otherwise lethal total body irradiation. To determine whether drugs used in supportive care and other commonly used antibiotics such as tetracycline function as radiation protectors or damage mitigators in vitro, 13 drugs were tested for radiation protection and radiation damage mitigation of 32D cl 3 hematopoietic progenitor cells in clonagenic survival curves in vitro. Antibiotic/Antifungal agents including cilastatin, amikacin, ceftazidine, vancomycin, tetracycline, doxycycline, ciprofloxacin, metronidazole, methacycline, minocycline, meclocycline, oxytetracycline and rolitetracycline were added in 1, 10, or 100 micromolar concentrations to murine interleukin-3-dependent hematopoietic progenitor cell line 32D cl 3 cells either before or after irradiation of 0 to 8 Gy. Control irradiated 32D cl 3 cells showed radiosensitivity comparable to freshly explanted mouse marrow hematopoietic progenitor cells (D(0) 1.1+/-0.1 Gy, N 1.5+/-0.4). Positive control GS-nitroxide JP4-039 (known radiation mitigator) treated 32D cl 3 cells were radioresistant (D(0) 1.2+/-0.1, N 5.8+/-2.4 (p=0.009)). Of the 13 drugs tested, tetracycline was found to be a significant radiation mitigator (D(0) 0.9+/-0.1, N 13.9+/-0.4 (p=0.0027)). Thus, the radiation dose-modifying effect of some antibiotics, but not those currently used in the supportive care (antibiotic/antifungal regimens) for marrow transplant patients, may act as radiation damage mitigators for hematopoietic cells as well as decreasing the growth and inflammatory response to microbial pathogens.

We have previously described DNA-dependent protein kinase (DNA-PKcs) mutations in horses and dogs that result in deficits in V(D)J recombination, DNA repair, and SCID. In this paper, we document substantial developmental growth defects in DNA-PKcs-deficient dogs that are not apparent in SCID mice. Fibroblast cell strains derived from either fetal or adult SCID dogs proliferate poorly in culture and undergo premature replicative senescence, somewhat reminiscent of cells derived from Ku-deficient mice. A limited number of animals have been immune reconstituted (by bone marrow transplantation) so that they can be maintained in a normal environment for long periods. Several of these animals have developed conditions associated with premature ageing at 2-3 years of age, roughly 20% of their expected lifespan. These conditions include intestinal malabsorption and primary neural cell neoplasia. These results suggest that DNA-PKcs deficiency is not tolerated equally in all species, perhaps providing insight into why DNA-PKcs deficiency has not been observed in humans. Finally, this study demonstrates the feasibility of maintaining SCID dogs for extended periods of time and documents their utility for bone marrow transplantation studies and as hosts for the propagation of xenografts. In sum, SCID dogs may present researchers with new possibilities for the development of animal models of human disease.

Dogs given nonmyeloablative conditioning and marrow grafts from 2 dog leukocyte antigen (DLA)-identical littermate donors developed stable trichimerism and stably accepted a subsequent kidney graft from one of the marrow donors without the need for immunosuppression. In this study, we used trichimeras to evaluate strategies for adoptive immunotherapy to solid tumors, using the kidney as a tumor surrogate. Three DLA-identical trichimeric recipients were established by simultaneously infusing marrow from 2 DLA-identical donor dogs into a DLA-identical recipient conditioned with 2 Gy of total body irradiation (TBI) and given a short course of postgraft immunosuppression. After stable hematopoietic engraftment was confirmed, a kidney was transplanted from 1 of the 2 marrow donors into each respective trichimeric recipient. Peripheral blood lymphocytes from each kidney donor were then used to sensitize the alternate marrow donor. The trichimeric recipients were given donor lymphocyte infusions (DLIs) from the sensitized dogs and monitored for chimerism, graft-versus-host disease (GVHD), and kidney rejection. After DLI, we observed both prompt rejection of the transplanted marrow and donor kidney and disappearance of corresponding hematopoietic chimerism. Presumably due to shared minor histocompatibility antigens, host chimerism also disappeared, and GVHD in skin, gut, and liver developed. The native kidneys, although exhibiting lymphocytic infiltration, remained functionally normal. This study demonstrates that under certain experimental conditions, the kidney--an organ ordinarily not involved in graft-versus-host reactions--can be targeted by sensitized donor lymphocytes.

Although hematopoietic cell transplantation (HCT) is generally accomplished using a single donor, multiple donors have been used to enhance the speed of engraftment, particularly in the case of umbilical cord blood grafts. Here we posed the question in the canine HCT model whether stable dual-donor chimerism could be established using 2 DLA-identical donors. We identified 8 DLA-identical littermate triplets in which the marrow recipients received 2 Gy total body irradiation followed by marrow infusions from 2 donors and postgrafting immunosuppression. All 8 dogs showed initial "trichimerism," which was sustained in 5 dogs, while 2 dogs rejected one of the allografts and remained mixed chimeras, and 1 dog rejected both allografts. Immune function in one trichimeric dog, as tested by mixed leukocyte culture response and antibody response to sheep red blood cells, was found to be normal. Five dogs received kidney grafts from one of their respective marrow donors at least 6 months after HCT without immunosuppressive drugs, and grafts in 4 dogs are surviving without rejection. In summary, following nonmyeloablative conditioning, simultaneous administration of marrow grafts from 2 DLA-identical littermates could result in sustained trichimerism, and immunologic tolerance could include a kidney graft from one of the marrow donors.

Objective: To evaluate the safety and efficacy of allogeneic hematopoietic cell transplantation (HCT) after myeloablative conditioning in patients with severe systemic sclerosis (SSc)., Methods: Eligibility criteria for the study included SSc patients with features indicative of a poor prognosis. The myeloablative conditioning regimen included busulfan, cyclophosphamide, and antithymocyte globulin. Prophylaxis for graft-versus-host disease (GVHD) consisted of cyclosporine and methotrexate. Bone marrow was transplanted from HLA-identical siblings., Results: Two patients with diffuse cutaneous SSc and lung involvement who were refractory to conventional immunosuppressive treatment were enrolled in the study. In patient 1, there were no complications related to the conditioning regimen, and GVHD did not develop after transplantation. At 5 years after HCT, there was nearly complete resolution of the scleroderma and marked improvement in physical functioning. Internal organ function improved (lung) or remained stable. On examination of serial skin biopsy samples, there was resolution of the dermal fibrosis. Patient 2 experienced skin toxicity from the conditioning regimen and hypertensive crisis that was likely related to high-dose corticosteroids given for treatment of GVHD. Although this patient experienced an improvement in scleroderma and overall functioning, a fatal opportunistic infection developed 17 months after HCT., Conclusion: Allogeneic HCT may result in sustained remission of SSc. GVHD and opportunistic infections are the major risks associated with allogeneic HCT for SSc, as for allogeneic HCT in general.

Severe hemolytic anemia in Basenji dogs secondary to pyruvate kinase deficiency can be corrected by allogeneic hematopoietic cell transplantation (HCT) from littermates with normal hematopoiesis after conventional myeloablative or nonmyeloablative conditioning regimens. If the levels of donor chimerism were low (<20%) after nonmyeloablative HCT, there was only partial correction of the hemolytic anemia. We next addressed whether allogeneic cell therapy after nonmyeloablative HCT would convert mixed to full hematopoietic chimerism, achieve sustained remission from hemolysis, and prevent progression of marrow fibrosis and liver cirrhosis. Three pyruvate kinase-deficient dogs were given HCT from their respective dog leukocyte antigen-identical littermates after nonmyeloablative conditioning with 200 cGy of total body irradiation. Postgrafting immunosuppression consisted of mycophenolate mofetil and cyclosporine. All 3 dogs engrafted and had mixed hematopoietic chimerism with donor levels ranging from 12% to 55% in bone marrow. In 2 of the 3 dogs, there were decreases in the levels of donor chimerism so that at 25 weeks after nonmyeloablative HCT, hemolysis recurred that was associated with increased reticulocyte counts. All 3 dogs then had 2 serial infusions of donor lymphocytes (DLI) from their respective donors at least 20 weeks apart to convert from mixed to full donor chimerism. Both dogs with recurrence of hemolytic anemia after nonmyeloablative HCT achieved higher levels of donor chimerism, with donor contributions ranging from 47% to 62% in the bone marrow and 50% to 69% and 16% to 25% in the granulocyte and mononuclear cell fractions of the peripheral blood, respectively, and with remission of the hemolytic anemia. One dog responded after the first DLI, and 5 weeks after the second DLI, the other dog converted to full donor chimerism. At last follow-up, all these dogs showed clinical improvement, as determined by increasing hematocrits and normal reticulocyte counts. Analysis of the marrow 3 years after HCT showed normal cellularity, a normal myeloid-erythroid ratio, and no or minimal marrow fibrosis. Liver biopsies demonstrated normal histologies with no or minimal fibrosis. We conclude that DLI after nonmyeloablative HCT can increase the levels of donor cells contributing to hematopoiesis in recipients, inducing remissions of the hemolytic process and preventing complications associated with iron overload.

BackgroundAllogeneic hematopoietic cell transplantation for hemophagocytic lymphohistiocytosis (HLH) disorders is associated with substantial morbidity and mortality.ObjectiveThe effect of conditioning regimen groups of varying intensity on outcomes after transplantation was examined to identify an optimal regimen or regimens for HLH disorders.MethodsWe studied 261 patients with HLH disorders transplanted between 2005 and 2018. Risk factors for transplantation outcomes by conditioning regimen groups were studied by Cox regression models.ResultsFour regimen groups were studied: (1) fludarabine (Flu) and melphalan (Mel) in 123 subjects; (2) Flu, Mel, and thiotepa (TT) in 28 subjects; (3) Flu and busulfan (Bu) in 14 subjects; and (4) Bu and cyclophosphamide (Cy) in 96 subjects. The day 100 incidence of veno-occlusive disease was lower with Flu/Mel (4%) and Flu/Mel/TT (0%) compared to Flu/Bu (14%) and Bu/Cy (22%) (P < .001). The 6-month incidence of viral infections was highest after Flu/Mel (72%) and Flu/Mel/TT (64%) compared to Flu/Bu (39%) and Bu/Cy (38%) (P < .001). Five-year event-free survival (alive and engrafted without additional cell product administration) was lower with Flu/Mel (44%) compared to Flu/Mel/TT (70%), Flu/Bu (79%), and Bu/Cy (61%) (P = .002). The corresponding 5-year overall survival values were 68%, 75%, 86%, and 64%, and did not differ by conditioning regimen (P = .19). Low event-free survival with Flu/Mel is attributed to high graft failure (42%) compared to Flu/Mel/TT (15%), Flu/Bu (7%), and Bu/Cy (18%) (P < .001).ConclusionsGiven the high rate of graft failure with Flu/Mel and the high rate of veno-occlusive disease with Bu/Cy and Flu/Bu, Flu/Mel/TT may be preferred for HLH disorders. Prospective studies are warranted.

Multiple sclerosis (MS) is a chronic, disabling, immune-mediated, demyelinating and degenerative disease of the central nervous system. Approved disease-modifying therapies may be incompletely effective in some patients with highly active relapsing disease and high risk of disability. The use of immunoablative or myeloablative therapy followed by autologous hematopoietic cell transplantation (AHCT) has been investigated in retrospective studies, clinical trials, and meta-analyses/systematic reviews as an approach to address this unmet clinical need. On behalf of the American Society for Blood and Bone Marrow Transplantation (ASBMT), a panel of experts in AHCT and MS convened to review available evidence and make recommendations on MS as an indication for AHCT. A review of recent literature identified 8 retrospective studies, 8 clinical trials, and 3 meta-analyses/systematic reviews. In aggregate, these studies indicate that AHCT is an efficacious and safe treatment for active relapsing forms of MS to prevent clinical relapse, magnetic resonance imaging-detectable lesion activity, and worsening disability and to reverse disability without unexpected adverse events. Based on the available evidence, the ASBMT recommends that treatment-refractory relapsing MS with high risk of future disability be considered a "standard of care, clinical evidence available" indication for AHCT. Collaboration of neurologists with expertise in treating MS and transplantation physicians with experience performing AHCT for autoimmune disease is crucial for ensuring appropriate patient selection and optimizing transplantation procedures to improve patient outcomes. Transplantation centers in the United States and Canada are strongly encouraged to report baseline and outcomes data on patients receiving AHCT for multiple sclerosis to the Center for International Blood and Marrow Transplant Research. [ABSTRACT FROM AUTHOR]

Patients with severe aplastic anemia (SAA) over 40 years of age are often not offered treatment with hematopoietic cell transplantation (HCT) because of concerns about treatment-related morbidity or mortality. To evaluate this risk, we analyzed outcomes after allogeneic HCT from HLA-identical sibling donors for all older patients with SAA at our center since 1988. The 23 consecutive patients ranged in age from 40 to 68 years. The conditioning regimen was cyclophosphamide (200 mg/kg) and horse antithymocyte globulin. Methotrexate and cyclosporine were given for postgrafting immunosuppression. The cumulative incidences of grades II, III, and IV acute graft-versus-host-disease were 30%, 4%, and 0%, respectively; that for chronic GVHD was 26%. With a median follow-up of 9.1 years, overall survival was 65%. Documented infections within 1 month before HCT were significantly associated with risk of early treatment-related mortality (P < .001). The median time to discontinuation of posttransplant immunosuppression was 6.2 (range: 5.9-92.0) months. Three patients developed superficial basal cell carcinoma between 5.5 and 15 years after HCT. Our data favor a practice of extending HLA-identical sibling HCT for treatment of SAA in patients older than 40 years of age who are without significant medical comorbidities. [Copyright &y& Elsevier]