PKH26 can transfer to host cells in vitro and vivo.

The fluorescent dye, PKH26, which mainly binds to the cell membrane, has been used as the cell tracer to locate the transplanted cells in host for a long time. However, there was no detailed report that whether the PKH26 dye was specific to the transplanted cells. Therefore, the aim of this article is to explore the effect of cells debris as the cracking cells from the PKH26-labeled adipose-derived stem cells (ADSCs) on the cells in vitro and the host in vivo. After we tested the proliferation and toxicity of PKH26 to the ADSCs by the Cell Count-8 kit and alamar blue assay, we constructed 2 models, coculturing lots of PKH26-labeled cell debris with the unlabeled ADSCs in vitro and injecting via the tail vein in rat, to evaluate the specificity of the PKH26 dye. The result indicated that the PKH26 didn't inhibit the proliferation and had no toxicity to the ADSCs compared with the unlabeled ADSCs, but the cell debris cracking from PKH26-labeled transplanted cells can cause the unlabeled cells to emit red fluorescence in vitro and also lead the tissues displaying red fluorescence in vivo. We can conclude that the PKH26 dye, used as a cell tracer for a long time, was not an ideal cell tracer.