Not quite. To continue the analogy, FDA are asking how do you...

Not quite. To continue the analogy, FDA are asking how do you know the liquid you got from the forest will cure patients when you collect them on different times/days/months/seasons or from a slightly different location or you have stored it for a while at the lab or it has rained that day or a squirrel peed on it and effected it somehow.

What FDA is asking is what specific attribute are you measuring which you know is the bit that has the 'magic' or active ingredient in it; that everyone is confident when that patient has chosen your treatment, it has been manufactured to a quality which contains the active ingredient at the correct dosage?

FDA is saying they are not sure MSB is measuring the quality parameters which make MSC's do what they do. MSB is saying they are and have evidence to back it up to clinical outcomes.

I think the FDA is really signalling to the expert panel: 'What do you think? Should MSB be monitoring anything else?' Having looked through the qualifications and job titles of the panel, I am not sure any of them have manufacturing or specific research background to answer this question. Appears to me it's just a question FDA need to ask for the record and see if anyone throws up any shop stoppers or brilliant ideas. I really can't see how all that gets resolved in 1.5 - 2 hr discussion window allowed in the AM session. Remembering a decision needs to be made that day and no decision is required for the AM session.

FDA can be a pain the arse in their formal approach but ultimately their entire mantra if I had to sum up in two phrases:
1. Data driven
2. Benefit vs risk decision making

I find it hard to believe either of those mantras will be not be met in Rem-L's BLA.