求翻译：然而，体外制备具有生物学活性的组织工程组织，并不是一件容易的事情，需要复杂培养环境，常需借助生物反应器才能实现。是什么意思？

However, preparation with biological activity in vitro tissue engineering of organization is not an easy thing, require complex training environment, often required with bioreactor can be achieved.