摘要：Three-dimensional (3D) tissue construction from individual cells is an important process in regenerative medicine to enhance cell functions. In transplantation of tissue-engineered constructs, a limited oxygen/nutrient supply due to insufficient vascular network formation causes cell death. Thus, it is necessary to develop a system for inducing vascular networks into 3D tissue constructs under hypoxic conditions. In our previous study (Ono, A.,et al., 2017), we developed a hypoxia-inducible transgene expression system in which a target gene can be expressed in response to hypoxic stress using hypoxia-responsive promoter RTP801 as a trigger, tTA transactivator as an amplifier, and oxygen-dependent degradation sequence as a noise canceler. In this study, to improve oxygen and nutritional limitation within engineered 3D tissue constructs, a hypoxia-responsive gene expression system for vascular endothelial growth factor (VEGF) was introduced into cells. We demonstrated that genetically engineered cells could regulate VEGF expression autonomously in an oxygen concentration-dependent manner. Using the genetically engineered cells, 3D tissue constructs were fabricated using a magnetic force-based tissue engineering technique (Ito, A.,et al., 2005). The tissue constructs were transplanted into mice to evaluate the feasibility of the hypoxia-responsive VEGF gene expression systemin vivo. The results indicated that the VEGF gene expression system is promising for the induction of vascular networks into 3D tissue constructs.
