I just had a brilliant idea! But there be spoilers for the newest Doctor Who, so I shall put it under a cut.
In the most recent ep, The Rebel Flesh, The Doctor seems to know something about the future of these Gangers. Every theory I've read so far has likened them to the Nestene Consciousness. But that's plastic, and these Gangers are flesh. The team calls them, calls the substance, "The Flesh".
I just realized where we've heard that term before in Doctor Who. At the hospital in New New York! The cat nurses refer to their test subjects as 'the flesh'. Now granted, that is millennia in the future and technically on a different planet, but it's possible the technology was kept for that long, or even lost and then rediscovered.
We'll have to see if it means anything. But I tell you now, if it gets mentioned at all, I will yell "I called that!" at the screen, and possibly jump up and down a bit.