Mobilization, collection, and immunomagnetic selection of peripheral blood CD34 cells in recovered aplastic anemia patients

Parameters affecting successful stem cell collections for genetic therapies in sickle cell disease

Emerging cellular therapies require the collection of peripheral blood hematopoietic stem cells (HSC) by apheresis for in vitro manipulation to accomplish gene addition or gene editing. These therapies require relatively large numbers of HSCs within a short time frame to generate an efficacious therapeutic product. This review focuses on the principal factors that affect collection outcomes, especially relevant to gene therapy for sickle cell disease.

Autologous cord blood transplantation in children with acquired severe aplastic anemia

OBJECTIVE

To investigate the efficacy of ACBT for acquired SAA in children.

METHODS

Four patients including three girls and one boy were diagnosed with acquired SAA. Their ages were 5, 3, 1, and 3 years, respectively. Patients received an immunoablative preparative regimen using low-dose antithymocyte globulin, cyclophosphamide, and fludarabine. The unrelated human umbilical cord MSC were infused before the autologous cord blood was transfused on day 0. The first and second patients were not treated with immunosuppressive agents after transplantation. The third and the fourth patients received cyclosporine A for half a year after transplantation followed by a 6-month taper.

RESULTS

Initial hematopoietic reconstitution was seen in all the four patients. There was no association between engraftment time and the number of total cells and CD34+ cells. Relapse was seen in the first case about half a year after the transplantation. The other three patients with durable hematopoietic reconstitution are with good quality of life. No GVHD was observed.

CONCLUSIONS

Three of four patients maintained prolonged hematopoiesis following an immunosuppressive-based preparative regimen and infusion of autologous cord blood cells. It is recommended that cyclosporine be maintained for 6 months after transplantation. ACBT could be considered for acquired SAA if available.

Successful autologous cord blood transplantation in a child with acquired severe aplastic anemia

Over 400 cases of pediatric SAA occur annually in the United States. A growing number of children with SAA may have had their stem cells harvested through cord blood collection. We describe a nine-yr-old male with SAA treated successfully with an autologous cord blood transplant following immunoablative chemotherapy. With the increasing number of people cryopreserving autologous cord blood, the use of autologous cord blood in the treatment of SAA might be considered as initial therapy. This case serves to discuss approaches to preparative therapy as well as the potential complications in this growing cohort of patients.

Autologous transplant in the treatment of severe aplastic anemia--a case report

The initial use of immunosuppressive therapy (IST) in severe aplastic anemia (sAA) or reapplication of IST-centered methods following disease relapse is successful only in well-selected patients. The potential treatment by autologous stem cell (SC) transplant in sAA is still an innovative/pioneering therapeutic approach. To our best knowledge, this is the second published case of autologous SC transplant in sAA. The aim of this work was to optimize mobilization and timing for SC harvesting - using our own controlled-rate cryopreservation - with higher CD34(+)/CD90(+) subset yield and recovery in order to obtain complete and long-term hematopoietic reconstitution following autologous SC transplant. We report a 35 year-old sAA male patient who initially underwent IST using rabbit ATG and Cyclosporine A (CsA). He was supportive transfusion dependent for the whole period of IST-phase. After the second IST-cycle, polymorphonuclear (PMN) cell count increase (>2.0 × 10(9)/L) was observed, when SC mobilization, two large volume leukapheresis procedures and following autologous transplant were performed. The yields of harvested CD34(+) and CD34(+)/CD90(+) cells were 5.75 × 10(6)/kgbm and 1.7 × 10(6)/kgbm, respectively. The quantity of applied CD34(+) and CD34(+)/CD90(+) cells in autologous SC transplant were 5.45 × 10(6)/kgbm (7-AAD(CD34)(+)(viability)=95.42%) and 1.63 × 10(6)/kgbm (7-AAD(CD34)(+)(/CD90)(+)(viability)=95.42%), respectively. Hematopoietic reconstitution registered due to second month after autologous SC transplant and he is 24 months in complete medullar, hematological and clinical remission, with normal cytogenetic status - applying only continuous CsA therapy. The results obtained strongly confirm that in sAA, with no allogeneic SC donor, autologous transplant can result in a successful clinical outcome. We suggest that CD34(+)/CD90(+) subset count in peripheral blood and/or cell-harvest could be more valuable predictive factor than total CD34(+) quantity of optimized collection-timing and superior treatment efficacy of autologous SC transplant in sAA.

Peripheral blood stem cell mobilization: new regimens, new cells, where do we stand

PURPOSE OF REVIEW

Granulocyte colony-stimulating factor-mobilized peripheral blood stem cells are widely used to reconstitute hematopoiesis; however, preclinical and clinical studies show that improvements to this mobilization can be achieved. We discuss the development of new mobilizing regimens and evaluation of new findings on mobilized stem cell populations that may improve the utility and convenience of peripheral blood stem cell transplant.

RECENT FINDINGS

Chemokines and their receptors regulate leukocyte trafficking, and altering chemokine signaling pathways mobilizes stem cells. In recent trials, combination use of the chemokine (C-X-C motif) receptor 4 antagonist AMD3100 and granulocyte colony-stimulating factor mobilized more CD34 cells in fewer days than granulocyte colony-stimulating factor alone and allowed more patients to proceed to autotransplant. In preclinical studies the chemokine GRObeta synergizes with granulocyte colony-stimulating factor and when used alone or with granulocyte colony-stimulating factor mobilizes more primitive hematopoietic stem cells with less apoptosis, higher integrin activation, lower CD26 expression and enhanced marrow homing compared with granulocyte colony-stimulating factor. Hematopoietic stem cells mobilized by GRObeta or AMD3100 demonstrate superior engraftment and contribution to chimerism in primary and secondary transplant studies in mice, and peripheral blood stem cells mobilized by AMD3100 and granulocyte colony-stimulating factor in patients demonstrate enhanced engraftment capabilities in immunodeficient mice.

SUMMARY

Alternate regimens differentially mobilize stem cell populations with unique intrinsic properties with the potential to expand the utility of hematopoietic transplantation. Continued mechanistic evaluation will be critical to our understanding of mechanisms of mobilization and their use in regenerative medicine.