Controlled spatial and temporal release of neurotrophic growth factor from genetically modified tissue engineering living scaffolds.

Peripheral nerve injuries (PNIs) affect thousands of patients yearly, often resulting in loss of function, sensation, and chronic pain. In critical-size defects, advanced surgical repair strategies often fail to restore full function. A key limitation is the lack of sustained, localized delivery of biological cues for axonal regeneration, such as growth factors. Glial-cell line-derived neurotrophic factor (GDNF) is known to promote axonal growth, Schwann cell migration, and neuronal survival, but uncontrolled release may cause axonal entrapment. We previously developed tissue-engineered nerve grafts (TENGs) composed of two neuronal populations connected by stretch-grown axons. In this study, we genetically modified the distal population to express human GDNF under a Tet-on inducible promoter, temporally controlling GDNF release through doxycycline administration. Modified TENGs survived implantation in a 1.5-cm rat sciatic nerve defect, supporting future studies. This approach offers a promising platform for spatially and temporally controlled neurotrophic factor delivery from tissue-engineered living scaffolds.