Vw. Vanbeusechem et al., RETROVIRUS-MEDIATED GENE-TRANSFER INTO RHESUS-MONKEY HEMATOPOIETIC STEM-CELLS - THE EFFECT OF VIRAL TITERS ON TRANSDUCTION EFFICIENCY, Human gene therapy, 4(3), 1993, pp. 239-247
We have generated a cell line, designated POAM-P1, shedding amphotropi
c recombinant retroviruses carrying the human adenosine deaminase (hAD
A) gene. It exhibits a 1 log increased retrovirus titer on NIH-3T3 cel
ls and a five-fold more efficient transduction of human ADA-deficient
T lymphocytes, as compared to the previously generated cell line POC-1
which produces the same recombinant hADA retrovirus. To study whether
the titer of retrovirus-producing cell lines influences the transduct
ion efficiency of hematopoietic stem cells in a co-culture setting, we
compared the POAM-P1 and POC-1 cell lines with respect to their gene
transfer efficiency on rhesus monkey bone marrow. Following co-cultiva
tion of rhesus monkey bone marrow with POAM-P1 cells, successful trans
duction could be demonstrated in approximately 10% of myeloid progenit
or colonies (CFU-C) and 0.1% of peripheral blood mononuclear cells (PB
MC) and granulocytes in vivo until > 1 year after autologous transplan
tation. In addition, the presence of functional hADA enzyme was detect
ed in red blood cells, PBMC, and granulocytes. Monkeys receiving POC-1
co-cultured bone marrow carried transduced blood cells for >2 years a
fter transplantation. Despite the higher retrovirus titer of POAM-P1 c
ells as compared to POC-1 cells, no difference was observed in gene tr
ansfer efficiency into CFU-C and long-term repopulating stem cells. Th
is shows that in our co-cultivation procedure the retrovirus titer was
not limiting the transduction efficiency of primate hematopoietic ste
m cells.