求翻译：组织工程组织的体外培养是一个长时间的过程，维持长期稳定的生化环境是获得良好组织培养效果的首要条件。但是，这一问题至今尚未得到很好的解决。是什么意思？

In vitro culture of tissue engineering organization is a long process, maintain long-term stability, chemical or biological environment is the prerequisite for tissue culture for good results. However, this problem has not been a very good solution.