Correction of the disease phenotype in canine leukocyte adhesion deficiency using ex vivo hematopoietic stem cell gene therapy.
Canine leukocyte adhesion deficiency (CLAD) represents the canine counter-part of the human disease leukocyte adhesion deficiency (LAD). Defects in the leukocyte integrin CD18 adhesion molecule in both CLAD and LAD lead to recurrent, life-threatening bacterial infections. We evaluated ex vivo retroviral-mediated gene therapy in CLAD using 2 nonmyeloablative conditioning regimens--200 cGy total body irradiation (TBI) or 10 mg/kg busulfan--with or without posttransplantation immunosuppression. In 6 of 11 treated CLAD dogs, therapeutic levels of CD18(+) leukocytes were achieved. Conditioning with either TBI or busulfan allowed long-term engraftment, and immunosuppression was not required for efficacy. The percentage of CD18(+) leukocytes in the peripheral blood progressively increased over 6 to 8 months after infusion to levels ranging from 1.26% to 8.37% at 1-year follow-up in the 6 dogs. These levels resulted in reversal or moderation of the severe CLAD phenotype. Linear amplification-mediated polymerase chain reaction assays indicated polyclonality of insertion sites. These results describe ex vivo hematopoietic stem cell gene transfer in a disease-specific, large animal model using 2 clinically applicable conditioning regimens, and they provide support for the use of nonmyeloablative conditioning regimens in preclinical protocols of retroviral-mediated gene transfer for nonmalignant hematopoietic diseases such as LAD.
Bauer
Thomas R
TR
Experimental Transplantation and Immunology Branch, National Cancer Institute, National Institutes of Health, 10 Center Dr, MSC1203, Bldg 10-CRC, Rm 3-3264, Bethesda, MD 20892-1203, USA. bauert@mail.nih.gov
Hai
Mehreen
M
Tuschong
Laura M
LM
Burkholder
Tanya H
TH
Gu
Yu-Chen
YC
Sokolic
Robert A
RA
Ferguson
Cole
C
Dunbar
Cynthia E
CE
Hickstein
Dennis D
DD
D000818:Animals; D018821:CD18 Antigens / Q000235:genetics; D004285:Dogs; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D018370:Leukocyte-Adhesion Deficiency Syndrome / Q000628:therapy*; D012190:Retroviridae; D014162:Transfection; D019172:Transplantation Conditioning / Q000379:methods*; D014916:Whole-Body Irradiation
D018821:CD18 Antigens