With the advent of recent molecular studies, nonspherocytic hemolytic anemia caused by red blood cell pyruvate kinase (PK) deficiency is now considered to be caused by a structural mutation of the PK-LR gene. Because PK deficiency is a monogenic disorder, the introduction of the normal PK gene into a patient's bone marrow stem cells should cure the disorder. To study the feasibility of gene therapy for PK deficiency, we first constructed the PK retrovirus pMNSM-hPK using human liver-type PK (LPK) cDNA and obtained a producer cell line of E86/AmPK. By using the supernatant of this virus-producer cell, we transduced NIH/3T3 cells, mouse leukemic cells (NFS60, FDCP-2), and human leukemic cells (K562, HEL). The expression of human LPK enzyme activity was ascertained from the retrovirally transduced NIH/3T3 cells. Northern blot analysis demonstrated the expression of the human LPK mRNA in each transduced cell line. Furthermore, bone marrow stem cells (c-kit+, Lin- , Thy-1lo) sorted by fluorescence-activated cell sorting were also transduced by the producer cells in the presence of interleukin-3 and interleukin-6, and were transplanted into lethally irradiated C57BL/6 mice. Polymerase chain reaction analysis demonstrated the expression of human LPK mRNA in both the peripheral blood and hematopoietic organs on day 30 and on day 135 of bone marrow transplantation.