If you don't understand what suffering is at a visceral level then no experimental contrivance will clarify the notion for you.
That's pure hand-waving.
Look: "I think this rock here is suffering. I can't prove it, but if you don't feel it at a visceral level then no experimental contrivance will clarify it for you"
I'm not claiming that rocks or artificially grown foetal brains are suffering. The people involved in this research claim they aren't - if the meaning of that claim is unclear the onus is on them to clarify it. Until such a time we are all at liberty to filter that claim through our own intuitively constructed concepts.
This seems significant:
http://www.theguardian.com/science/2015/aug/18/first-almost-fully-formed-human-brain-grown-in-lab-researchers-claim