The Science Will Do The Talking, page-9

What stops telomeres from shortening is the enzyme telomerase.

CYP doesn't mess around with the length of the telomeres - don't need to, the cells aren't passaged so much that the short telomeres become a problem. Generally in somatic cells the telomeres get shorter afer each cell division but with eEmbryonic stem cells and iPSCs probably they'd have the enzyme telomerase produced naturally and so would rebuild the telomeres.

You wouldn't put iPSCs into a 3D bioreactor to get MSCs in large volumes you seed the 3D bioreactor with the single cells that go onto to form colonies. You wouldn't put telomerase into a 3d bioreactor either. Wrong tool at wrong scale.

As I understand 3D cuture it is essentially 2D culture except you have cells adhering to particles that are floating in 3D volumes. A 3D bioreactor is essentially like 2D except with a lot more adhere surface per unit area.

I think this is sort of right - but I'm responding quickly and could be wrong.