Delivery of glial cell line-derived neurotrophic factor (GDNF) has provided benefits to Parkinsonian patients and is currently being tested in a Phase 1/2a clinical trial for ALS patients. However, chronic trophic factor delivery prohibits dose adjustment or shut off in the event of side effects. To address this, the Inventors engineered a stably integrating, third-generation doxycycline-regulated vector, allowing inducible and reversible expression of a therapeutic molecule. Human iPSC-derived neural progenitors were stably transfected with the vector, expanded and transplanted into the adult mouse brain. The Inventors observed that the addition and withdrawal of doxycycline led to GDNF expression that could be induced and reversed multiple times, demonstrating that doxycycline can penetrate the graft and regulate transgene expression in vivo. The Inventors' findings provide a proof of concept for combining gene and stem cell therapy for effective modulation of ectopic protein expression in transplanted cells.
