Heterogeneity of F cells in β‐thalassemia

BACKGROUND: Fetal hemoglobin (HbF), which is largely replaced after birth by the adult Hb, is concentrated in a few “F cells.” Their number significantly increases in certain physiologic and clinical situations, including in β‐thalassemia (β‐thal). Their quantification is used to detect fetal–maternal hemorrhage (FMH), where fetal cells enter the maternal circulation. We were confronted with a pregnant woman with β‐thal who was suspected to have FMH. To establish the usefulness of a flow cytometric procedure to differentiate between fetal cells and the maternal F cells, we screened adult β‐thal patients. STUDY DESIGN AND METHODS: Blood samples were simultaneously stained with fluorescent antibodies to HbF and to carbonic anhydrase (CA) isotype II, which is specific to adult red blood cells (RBCs). RESULTS: A heterogeneous distribution of RBCs with respect to HbF and CA expression was observed: adult non‐F cells (CA+HbF–) and F cells (CA+HbF+/HbF++) as well as F cells with characteristics of fetal cells (CA–HbF++). CONCLUSIONS: The presence of CA–HbF++ RBCs in nonpregnant women, and even men, with thal indicates that the CA/HbF method is inappropriate for detection of FMH. The coexistence of F cells carrying fetal or adult markers suggests that they originate from two types of stem cell, adult and fetal, lineages. Normally, the fetal lineage is insignificant, but in β‐thal, as HbF‐containing RBCs have a selective advantage, the “fetal” lineage gains significance.     

Agonism of Wnt–β‐catenin signalling promotes mesenchymal stem cell (MSC) expansion

Promoting mesenchymal stem cell (MSC) proliferation has numerous applications in stem cell therapies, particularly in the area of regenerative medicine. In order for cell‐based regenerative approaches to be realized, MSC proliferation must be achieved in a controlled manner without compromising stem cell differentiation capacities. Here we demonstrate that 6‐bromoindirubin‐3′‐oxime (BIO) increases MSC β‐catenin activity 106‐fold and stem cell‐associated gene expression ~33‐fold, respectively, over untreated controls. Subsequently, BIO treatment increases MSC populations 1.8‐fold in typical 2D culture conditions, as well as 1.3‐fold when encapsulated within hydrogels compared to untreated cells. Furthermore, we demonstrate that BIO treatment does not reduce MSC multipotency where MSCs maintain their ability to differentiate into osteoblasts, chondrocytes and adipocytes using standard conditions. Taken together, our results demonstrate BIO's potential utility as a proliferative agent for cell transplantation and tissue regeneration. Copyright © 2013 John Wiley & Sons, Ltd.     

Depletion of αβ+ T cells for a haploidentical hematopoietic stem cell transplantation in children

A consistent and reproducible depletion technique is crucial for the successful transplantation of an ex vivo depleted graft. Our aim was to evaluate the efficacy of an ex vivo technique for depletion of αβ⁺ T cells using a biotinylated anti‐TCRαβ monoclonal antibody, which was performed by one clinical nurse specialist. Between 2012 and 2017, 119 depletion procedures from 216 apheresis using the anti‐TCRαβ monoclonal antibody were performed on 105 pediatric patients. The median log depletion of αβ⁺ T cells was 4.0 (range, 2.5‐5.0). The median recovery rates of CD34⁺, NK, and γδ⁺ T cells were 90.4%, 74.9%, and 75.9%, respectively. The efficacy of depletion of αβ⁺ T cells significantly improved over time and the duration of the depletion procedure significantly decreased over time. Our study demonstrated that this procedure for depletion of αβ⁺ T cells by skilled staff is highly effective at depleting target cells and obtaining CD34+ progenitor cells.     

Delayed hemolytic transfusion reaction with hyperhemolysis after first red blood cell transfusion in child with β‐thalassemia: challenges in treatment

BACKGROUND: Delayed hemolytic transfusion reaction (DHTR) can manifest with hyperhemolysis, a serious complication of red blood cell (RBC) transfusions. This has mostly been described in sickle cell anemia but occasionally in β‐thalassemia. Treatment is challenging; immunosuppressive medication has been reported to be useful by some but not others. CASE REPORT: A 1.5‐year‐old girl with homozygous β‐thalassemia was put on a regular RBC transfusion program because of anemia with stunted growth and abnormal bone development. After the first transfusion she developed DHTR with hyperhemolysis. Further RBC transfusions could not be avoided. Despite treatment with prednisone, immunoglobulins, rituximab, and azathioprine hemolysis continued. She received an allogeneic bone marrow transplantation after conditioning using cyclophosphamide, treosulfan, melfalan, and ATG. The transplantation was followed by treatment with cyclosporin A, methotrexate, and prednisone. Because of poor engraftment and later rejection, she received a retransplantation after conditioning using fludarabine instead of cyclophosphamide and was subsequently treated with prednisone, but hemolysis continued. Only after splenectomy did she no longer need RBC transfusions and the direct antiglobulin test turned negative. DISCUSSION AND CONCLUSION: Treatment of DHTR remains challenging. The role of immunosuppressive medication such as azathioprine, cyclosporin A, and rituximab remains to be seen. Splenectomy may be helpful. Mainstay is to minimize RBC transfusions as much as possible.