Mammalian cells in research labs are grown in media that is composed of 1) multiple powdered components that are readily obtainable through isolation from bacteria/yeast or synthesis and, 2) 10% FBS (fetal bovine serum). Until these cultured meat companies can come up with a suitable replacement for FBS, due to environmental, moral, cost, etc concerns, none of these solutions are terribly viable. I personally wouldn't want to eat (or pay for) a tiger streak that required liters of FBS to grow.