Yoichi Takaue

Peripheral Blood Stem Cell Autografts in Children with Acute Lymphoblastic Leukemia and Lymphoma: Updated Experience

Peripheral blood stem cells (PBSC) in autografts (PBSCT) were given to 16 children with high-risk acute lymphoblastic leukemia (ALL) or non-Hodgkins lymphoma (NHL). Harvest of PBSC is a safe, reliable procedure with low morbidity in children with cancer, and cryopreserved PBSC are useful in reducing cytopenia following marrow-ablative chemotherapy. The CFU-GM content of the thawed grafts is an important determinant of hematopoietic recovery after PBSCT. Whereas not all collections from children who had received intensive chemotherapy yielded sufficient progenitors for a safe graft, the value of preleukapheresis use of granulocyte colony-stimulating factor to expand the transplantable stem cell pool was not proven. After marrow-ablative chemotherapy without total body irradiation, three children who underwent PBSCT at refractory relapse died within 3 months. However, eight of the remaining 13 children are currently alive and disease-free, 5-29 months after PBSCT.

Combination of recombinant cytokines fails to produce ex vivo expansion of human blood hematopoietic progenitor cells.

SummaryThe concept of ex vivo expansion of the human progenitor cell population was tested in this study. In the presence of interleukin-3 and -6 we compared the abilities of various liquid culture conditions of human blood-derived hematopoietic progenitor cells to yield a suitable condition for the expansion of blood progenitor cells. Although the best result was obtained in the gas-permeable bag culture system, the enhancement effect (maximum of 3.8-fold for granulocyte/macrophage colony-forming units and 3.0-fold for erythroid burst-forming units) lasted for only a short period (< 6 d). The results of this study are disappointing for clinical use, and attempts with currently available technology appear to be limited in their potential.

Collection of Peripheral Blood Stem Cells for Autografts in Children with Cancer

Peripheral blood stem cell (PBSC) autografts have been mainly performed in adults patients; there have been only a few pediatric studies [1–4]. Problems associated with apheresis procedures in small children include access to blood and intolerance of extracorporeal circulation. In addition, children may be at a greater risk than adult patients for significant cardiovascular morbidity due to the rapid blood volume changes during apheresis. However, a larger proliferative capacity of hematopoiesis may exist in children than in adult patients and more PBSC per body weight can be collected in children, making PBSC autografts a suitable procedure for children.

Successful autograft with peripheral blood stem cells in a child with T-lymphoblastic leukemia

Peripheral blood stem cells (PBSC) were collected by two leukaphereses and cryopreserved in a 3-year-old girl with T-lymphoblastic leukemia; this was after remission was induced by an investigative regimen when she failed to respond to a first-line induction therapy. The patient received marrow-ablative chemotherapy 4.5 months after the diagnosis; this was followed by the infusion of thawed PBSC (203 x 10(4) CFU-GM/kg). The peripheral granulocyte count reached 0.5 x 10(9)/L by day +7 and the platelet count reached 20 x 10(9)/L by day + 9. Thereafter, the leukocyte count increased to 38 x 10(9)/L by day +14, with a gradual decline to normal levels. She has remained in unmaintained, complete remission 47 months after the autograft, with full school activity. This case illustrates the PBSC autograft is useful as an alternative to bone-marrow transplantation in a selected patient population, and extends the application of cure-oriented therapy to refractory childhood leukemia.

A simplified and rapid limiting dilution assay of T lymphocytes

We report here the development of an alternative limiting dilution assay (LDA) of T lymphocytes (T cells). Blood mononuclear cells were first stimulated for 60 hr with PHA and then cultured in microwells in the presence of recombinant interleukin-2 without feeder cells. After 4 days of culture, wells were scored for proliferation. Clonal expansion of T cells followed the single-hit model of the Poisson distribution. The progenitor frequency (f) in the mononuclear cells and E-rosette-positive cells from normal donors were 0.082 +/- 0.025 (n = 12) and 0.236 +/- 0.029 (n = 5), respectively, but this was markedly decreased in patients who underwent marrow-ablative chemotherapy and autografts with blood hematopoietic stem cells. This LDA system should be of value in routine use for the evaluation of T cell proliferative activities.

Peripheral Blood Stem Cell Autografts in Children with Acute Leukemia and Lymphoma

There is considerable interest in the use of peripheral blood hematopoietic stem cells (PBSC) in autograft settings (PBSCT), and in this paper, a clinical and laboratory experience of PBSCT at a single institute is presented. Twenty-eight children with various types of cancer underwent a total of 90 leukaphereses to collect PBSC and 17 of them subsequently received marrow-ablative therapy and autografts with such collected and stored PBSC. We found that frozen-thawed progenitor dose is important in determining the rate of hematopoietic recovery and that cytoreductive regimens without TBI used in the study are effective against leukemia in the current standards. Although it is not known yet whether PBSCT is better than autologous bone marrow transplantation to prolong the remission interval, and ultimately the cure, the preliminary clinical data justify the incorporation of PBSCT in the design of a pilot therapeutic protocol for the salvage treatment of refractory acute leukemias/lymphoma. Not all collections from patients yield a sufficient number of progenitors for a safe autograft, but the value of preleukapheresis administration of G-CSF to such patients to expand the stem cell pool awaits proof.