Hematopoietic cell transplantation in the twitcher mouse. The effects of pretransplant conditioning with graded doses of busulfan.
The effects of congenic hematopoietic cell transplantation (HCT; transplantation of bone marrow and spleen cells) after graded doses of busulfan (BU), a myeloablative but nonimmunosuppressive alkylating agent, were evaluated in the twitcher mouse model of human galactosylceramidase deficiency, a demyelinating sphingolipid storage disease. C57BL/6 twitcher mice (immunophenotype Ly-5.1) were given 10 to 50 mg/kg of BU or total-body irradiation (9.0 Gy) at age nine days and HCT from congenic Ly-5.2 donors 24 hr later. The 30-day post-HCT survival, an indicator of tolerance of the preparative regimen, was at least 83% in twitcher mice given 45 mg/kg or less of BU, was 50% in recipients of 50 mg/kg BU and 75% in TBI-conditioned twitchers. The lifespan of twitcher mice given HCT after 10 or 20 mg/kg of BU was similar to that of untreated twitchers (median survival, 42 days; range, 30-47). In contrast, mice transplanted after 35 to 50 mg/kg of BU had significantly prolonged survival (median, 82 days; range, 56-208) and stabilization of hindlimb paralysis, similar to TBI-conditioned recipients. Post-HCT repopulation by donor Ly-5.2 cells was determined by flow cytometry. Thirty days after HCT, only 11-15% of lymphohematopoietic cells in blood, bone marrow, and spleens were of Ly-5.2 donor origin in twitcher mice transplanted after 10 mg/kg of BU but 60-80% were of Ly-5.2 donor origin in mice transplanted after higher doses of BU. These levels further increased to 70-90% by 90 days after HCT, comparable to that seen after TBI. Levels of galactosylceramidase in livers, spleens, and brains of twitchers transplanted after 35-50 mg/kg of BU or after TBI increased to 30-116% of normal control values by 90 days after HCT. Conditioning for HCT with as little as 35 mg/kg of BU provides minimal peritransplant mortality, rapid and sustained establishment of donor lymphohematopoiesis, replacement of lysosomal hydrolase, and prolonged survival in this murine model of human sphingolipidosis.
Yeager
A M
AM
Oncology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287.
Shinn
C
C
Shinohara
M
M
Pardoll
D M
DM
D000818:Animals; D016026:Bone Marrow Transplantation; D001921:Brain / Q000201:enzymology; D002066:Busulfan / Q000627:therapeutic use*; D005698:Galactosylceramidase / Q000378:metabolism; D006085:Graft Survival / Q000276:immunology / Q000502:physiology*; D018380:Hematopoietic Stem Cell Transplantation; D007165:Immunosuppression Therapy / Q000379:methods; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D051379:Mice; D008810:Mice, Inbred C57BL; D008818:Mice, Neurologic Mutants; D013154:Spleen / Q000201:enzymology / Q000637:transplantation; D014916:Whole-Body Irradiation
D007166:Immunosuppressive Agents; D005698:Galactosylceramidase; D002066:Busulfan