Near-infrared light controlled transplanted cells to treat spinal cord injury

PROJECT SUMMARY The goal of this project is to develop a prototype transplantation technology based on optogenetically controlled Schwann cells (SCs) and test its efficacy in a rat spinal cord injury (SCI) model. The benefits of using SCs in improving recovery after SCI are well characterized in animal models, yet they have poorly transferred to clinical

trials. One major shortcoming of applying SCs in humans involves late injection due to the need for lengthy preparation of autologous SCs. Other major issues concern fast decreases in SC viability and pro-regenerative capacity following transplantation. We intend to address these deficiencies by engineering SCs with higher

immune tolerance, and enhanced neuroprotective and neurostimulatory properties. These parameters of the engineered SCs will be controlled with light in the near-infrared window (NIRW) of the spectrum via the recently engineered bacteriophytochrome-based optogenetic system. The NIRW light penetrates deep into mammalian

tissues, including the spinal cord. Extracorporeal NIRW light-emitting diodes positioned over the skin will keep engineered SCs in the active state only at the SCI site. Our preliminary results show the feasibility of controlling gene expression in SCs by a bacteriophytochrome-based gene circuit, and the possibility to deliver NIRW light

to the spinal cords of rats for extended periods of time. In aim 1, we will engineer optogenetic circuits for NIRW light-inducible expression and secretion of an immunomodulatory cytokine that will dampen the inflammatory and acquired immune responses thus protecting engineered SCs in the irradiated SCI area. This will allow the

use of allogeneic SCs thus enabling cell transplantation at acute or sub-acute stages of SCI and avoiding the delay of propagating autologous SCs cells. The engineered SCs will also express, in a light-dependent manner, a neurotrophic factor that promotes neuronal regeneration. Prior to transplantation, the light-inducible immune

suppressive and pro-regenerative properties of the engineered SCs will be evaluated in syngeneic and allogeneic co-cultures with immune cells and neurons. In aim 2, we will test performance of the NIRW light- activated allogeneic SCs in a rat model of contusion SCI. We will assess the abundance, activation and

localization of the transplanted SCs, the immunological environment at the SCI site, and preliminary assess functional recovery of the animals. This project will be carried out by two research teams with complementary expertise in NIRW optogenetics, neuronal repair and SCI. The high risk associated with engineering and

application of optogenetically controlled SCs is mitigated by the potential payoff of developing an allogeneic cell transplantation therapy that can bring the benefits of SCs observed in animal studies to human SCI patients. Further, the proof of concept that transplanted cells can be controlled with NIRW light at the SCI site will broaden

application of the NIRW optogenetics to the pro-regenerative cells beyond SCs.