TRANSPLANTATION OF LAC-Z-TRANSDUCED MICROVASCULAR ENDOTHELIAL-CELLS INTO THE SKELETAL-MUSCLE CAPILLARY BED OF THE RAT HINDLIMB OCCURS INDEPENDENT OF THE DURATION OF FEMORAL-ARTERY OCCLUSION AFTER INJECTION OF CELLS

The skeletal muscle capillary bed may be an ideal recipient site for t ransplantation of genetically modified autologous endothelial cells an d thus provide a basis for a technique of somatic gene therapy that wo uld be applicable to a variety of acquired and inherited human disease s. The purpose of this study was to test the hypothesis that adhesion of lac-Z-transduced microvascular endothelial cells (MVEC) in the skel etal muscle capillary bed in vivo is dependent on the duration of arte rial occlusion after injection of the transduced MVEC. MVEC derived fr om the abdominal fat pad of syngeneic rats (Wistar F-455) were transfe cted with the BAG vector, a replication-incompetent retroviral vector containing the lac-Z gene for beta-galactosidase and the Tn5 gene for selection of the transduced cells by the neomycin analogue, G418. lac- Z-transduced MVEC were radiolabeled with I-125-PKH-95, and, after the femoral artery was occluded for 10 min, these cells (1 to 2 X 10(6)) w ere injected intraarterially into the rat hindlimb. In the experimenta l groups the femoral artery clamp was removed at 0, 60, or 120 min aft er injection. A control group without pre- or postinjection femoral ar terial occlusion was also studied. Adhesion of MVEC in the skeletal mu scle capillary bed (mean percentage of injected I-125 activity) was de termined in groups of 4 rats at 1 day, 1 week, and 1 month after injec tion. Adhesion of the transduced MVEC did not increase as the duration of femoral artery occlusion after injection was increased. The highes t rate was found in the group subjected to only a 10-min preclamp (32% at 1 day, 17% at 1 week, and 15% at 1 month). These results indicate that mechanical forces such as capillary shear rate and perfusion pres sure may not be important determinants of adhesion and incorporation o f transduced MVEC into skeletal muscle capillaries. Nevertheless, thes e results document significant adhesion and persistence of genetically modified MVEC transplanted into the capillary bed of the skeletal mus cle. (C) 1994 Academic Press, Inc.