As a type 1 this sounds great, but my concern is if you have this sack of cells sitting in your body that's insulated from the immune system, what happens if so

As a type 1 this sounds great, but my concern is if you have this sack of cells sitting in your body that's insulated from the immune system, what happens if some kind of infection manages to take hold inside of the sack? I don't know how common it is for instance for something like a virus to infect pancreas cells, but it seems like if one did manage to take hold inside of this "device" that could be incredibly bad. I'm also working on the assumption that this same membrane might protect it from bacterial infection, but that's also a big assumption, and if it doesn't that seems like it could be even worse.