Even when you have single cells that want to grow by themselves like yeast its very hard to mantain a sterile process. Thats why lager became the most common beer type. It alows you to run bio reactors at very cold temperatures to give the desired yeast time to outcompete the others. And thus you need to spend less efort mantaining a sterile situation.

I cant imagine how hard is to mantain a sterile enviorment with meat cells.