Haematopoietic stem cell transplantation to treat aplastic anaemia

Pregnancy-associated aplastic anemia: a case-based review

Introduction: Pregnancy-associated aplastic anemia (pAA) occurs when aplastic anemia (AA) is diagnosed for the first time during pregnancy and it is a rare but serious condition leading to severe maternal and fetal complications. It is unknown whether pregnancy triggers bone marrow failure or if this state is unrelated to the pathogenesis of pAA.Areas covered: In this review, three new cases of pAA are presented and its controversial etiologic relationship with pregnancy, its atypical presentation, and management are also discussed. Furthermore, a literature review of pAA cases between 1975 and 2020 was performed in PubMed, accessed via the National Library of Medicine PubMed interface. Keywords included 'aplastic anemia' AND 'pregnancy'. We found 54 cases reported in the literature with a clear diagnosis of pAA.Expert opinion: The diagnosis of pAA is challenging since pregnancy is associated with physiologic hematological changes in the complete blood count which can mask the disease. Meticulous monitoring and adequate support therapy given by a trained multidisciplinary team have the potential to improve outcomes for women and their neonates. All women should receive frequent assessments to optimize their care during pregnancy and after delivery, definitive treatment should be offered.

Long-term results of allogeneic peripheral blood hematopoietic stem cell transplantation for severe aplastic anemia

OBJECTIVE

Aplastic anemia (AA) is a life-threatening disorder and may be associated with significant morbidity and mortality Currently, the first treatment option is allogeneic hematopoietic stem cell transplant (allo-HSCT) for patients younger than 40 years. Bone marrow is recommended as the stem cell source due to less graft versus host disease (GVHD) risk and better outcomes than peripheral blood (PB)-derived stem cell. The aim of this study is to share the data of AA patients who have underwent PB-derived allo-HSCT in our bone marrow transplantation center.

METHODS

Twenty-seven patients who underwent PB-derived allo-HSCT from human leukocyte antigen matched sibling donors were analyzed retrospectively.

RESULTS

The median follow-up time was 95.2 months (range, 4.8-235 months). The 10-year survival was 89 %. The median neutrophil and platelet engraftment time was 11 days (range, 9-16 days) and 13 days (range, 11-29 days), respectively. Primary platelet engraftment failure was observed in 1 patient (3.7 %). Acute and chronic GVHD observed in 2 (7.4 %) and 3 (11.1 %) patients, respectively. Neutropenic fever was observed in 13 (44.8 %) of patients until the engraftment after allo-HSCT. One patient died due to CMV infections, two died due to septic shock secondary to fungal infection.

CONCLUSION

Although there is no prospective data directly comparing BM with PB as stem cell source in AA, observational studies indicates better OS with BM. PB can be used in certain situations such as higher risk for graft failure and donor preference. This study demonstrated that PB-derived stem cell seems to be a reasonable alternative to BM.

Antibodies in the treatment of aplastic anemia

Antibodies have been the cornerstone of treatment of acquired aplastic anemia for more than 25 years. Treatment with antithymocyte globulin (ATG) is considered pivotal and the addition of cyclosporine improves the overall response rate. This antibody is heterogeneous and horse ATG is apparently more effective than rabbit ATG. Several issues remain unsolved in relation to the combination of ATG and cyclosporine: cost, toxicity and late clonal disorders. In recent years, alternative immunosuppressive therapy has been proposed and new antibodies have emerged: porcine ATG, alemtuzumab, daclizumab, and rituximab. Experience with these antibodies is limited to a few studies with alemtuzumab being the most promising, but the results are interesting and provocative. More studies are needed to find the perfect antibody.

Subcutaneous alemtuzumab plus cyclosporine for the treatment of aplastic anemia

Aplastic anemia (AA) is most frequently due to autoimmune attack on its own stem cells. Alemtuzumab is a monoclonal antibody which recognizes the CD52 antigen on the surface of T and B cells. It has proved useful in autoimmune diseases, lymphoproliferative conditions, and graft versus host disease. Based on its immunosuppressive properties, we treated 14 AA patients with alemtuzumab. Median age was 23 years. Ten milligrams of alemtuzumab were injected subcutaneously each day for five consecutive days. Cyclosporine A was also administered orally at a dose of 2 mg/kg every 12 h for 3 months, and then gradually tapered. Response to alemtuzumab was followed for a median of 20 months. There were eight responses (57.1%), two complete and six partial. Whereas six (42.8%) patients were non-responders. Median complete blood count values on alemtuzumab responders were Hb 13.1 mg/dL, absolute neutrophil count 2.4 x 10(9)/L, and platelets 97.5 x 10(9)/L. A good response was produced in 57% of AA patients with the administration of alemtuzumab, who lacked a stem cell donor.

Marrow graft rejection by repeated transfusions of allogeneic donor spleen cells

Many hematological diseases require long-term transfusion support, which causes production of donor-reactive antibodies in sensitized recipients. Sensitized patients are at an increased risk for graft rejection when they undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT). Here, we established a highly sensitized murine model to investigate the mechanism of donor graft rejection. After BALB/c mice were repeatedly transfused with allogeneic spleen cells from C57BL/6 mice, there was a significant increase in complement-dependent cytotoxicity in the serum of sensitized mice. For transplantation, 1 x 10(7) bone marrow cells (BMCs) from C57BL/6 mice were injected into lethally irradiated recipient BALB/c mice. Sensitized mice died between 12 and 15 days post-transplantation, while non-sensitized mice remained alive after 28 days. The hematopoietic recovery rate declined over time in sensitized recipients. The homing trace assay showed a rapid disappearance of donor BMCs in the spleen and bone marrow of sensitized recipients. In addition, the recipient cells and antibodies in the sensitized serum were capable of inducing high level of cell- and complement-mediated cytotoxicity to the donor graft. Our finding may explain the impaired hematopoietic stem cell homing and poor hematopoietic engraftment observed in highly sensitized allo-HSCT patients.