Isolated Mitochondria with Tissue Culture Cells

Experiments were undertaken to study the effect of introducing isolated mammalian cell mito chondria into tissue culture cells. The D N A of isolated mitochondria was labeled in vitro with 3 Hthymidine. Incorporation of 3H-thymidine into mitochondrial D N A was increased tenfold by the addition of bovine serum albumin and sucrose to the assay. Labeled HeLa cell mitochondria were fused with WI38 (human fibroblast) and I-T-22 (Bromodeoxyuridine resistant mouse cell line) cells in the presence of Sendai virus and autoradiographs were made. The results indicated that isolated mitochondria may have been introduced into the cells by the fusion process. Fusion of mitochondria isolated from mouse tumor cell lines with isogenic primary mouse embryo fibroblasts induced permanent growth of these cells in tissue culture, whereas isolated mitochondria of mouse embryo fibroblasts or allogenic tumor cells did not have this effect.