Depends who you ask:

some would say that it's vegan as long as no animal has suffered or been deprived for your meal, meaning that lab grown qualifies.

Others, such as the crazies in the vegan circle jerk community, believe that as long as it's ever been in the same zip code as a leather belt, it can never be vegan.

That last one is exaggerated, of course, but nowhere near as much as you'd hope..