Rescue of Pyruvate Kinase Deficiency in Mice by Gene Therapy Using the Human IsoenzymeNestor W Meza1,2, Maria E Alonso-Ferrero1, Susana Navarro1, Oscar Quintana-Bustamante1, Antonio Valeri1, Maria Garcia-Gomez1, Juan A Bueren1, Jose M Bautista3 and Jose C Segovia1 1. 1Hematopoiesis and Gene Therapy Division. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT) y Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), Madrid, Spain 2. 2LABIEMET, School of Medicine of Táchira, Universidad de los Andes, San Cristóbal, Venezuela 3. 3Department of Biochemistry and Molecular Biology IV, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, SpainCorrespondence: Jose C Segovia, Hematopoiesis and Gene Therapy Division, CIEMAT/CIBER-ER, Avenue. Complutense 22, 28040 Madrid, Spain. E-mail: jc.segovia@ciemat.esReceived 7 April 2009; Accepted 1 August 2009; Published online 15 September 2009.Top of pageAbstractHuman erythrocyte R-type pyruvate kinase deficiency (PKD) is a disorder caused by mutations in the PKLR gene that produces chronic nonspherocytic hemolytic anemia. Besides periodic blood transfusion and splenectomy, severe cases require bone marrow (BM) transplant, which makes this disease a good candidate for gene therapy. Here, the normal human R-type pyruvate kinase (hRPK) complementary (cDNA) was expressed in hematopoietic stem cells (HSCs) derived from pklr deficient mice, using a retroviral vector system. These mice show a similar red blood cell phenotype to that observed in human PKD. Transduced HSCs were transplanted into myeloablated adult PKD mice or in utero injected into nonconditioned PKD fetuses. In the myeloablated recipients, the hematological manifestations of PKD were completely resolved and normal percentages of late erythroid progenitors, reticulocyte and erythrocyte counts, hemoglobin levels and erythrocyte biochemistry were restored. Corrected cells preserved their rescuing capacity after secondary and tertiary transplant. When corrected cells were in utero transplanted, partial correction of the erythrocyte disease was obtained, although a very low number of corrected cells became engrafted, suggesting a different efficiency of cell therapy applied in utero. Our data suggest that transduction of human RPK cDNA in PKLR mutated HSCs could be an effective strategy in severe cases of PKD.