Ah you're right. I misread "between" in the opening paragraphs of this article and admittedly pasted the link before fully reading the article oops :D

I'd assumed "between" was about this: https://en.wikipedia.org/wiki/Horizontal_transfer_of_mitocho...

And also this: https://www.sciencedirect.com/science/article/pii/S156772491...

Not in that article, yet there are studies that claim they can move between cells: https://www.pnas.org/doi/full/10.1073/pnas.0510511103