In the present project, our research team is investigating the possibility of using motor neurons that have been developed from human embryonic stem cells to replace lost motor neurons in the spinal cord of a large mammal. The project is of importance for better understanding of the translation of promising cell survival studies in rodents to a research model that more closely mimics the human condition. The findings may help the development of cellular treatments for injuries that affect both the spinal cord and spinal nerve roots as well as degenerative conditions that affect spinal cord motor neurons.
During the first year of the project, we have obtained the necessary institutional approvals for experimental studies and and use of human stem cells. the planned studies at both UCLA and UC Davis as well as obtained additional infrastructure and equipment. We have also further developed our in vitro protocols for the production of larger volumes of motor neurons from human embryonic stem cell. These studies have shown that we can grow human embryonic stem cells to develop into motor neurons in vitro and that these cells maintain motor neuron-like properties, such as being able to develop connections with muscle cells in a tissue culture setting. The tissue cultures also show reliable growth and robust differentiation of a large portion of cells to early forms of motor neurons and motor neurons with more differentiated features.
Survival of transplanted human cells in experimental models can be challenging and dependent on immuno-suppressive treatments. Based on recent advancements in the the field of transplant biology, we have adjusted our planned immuno-suppressive treatment plan to allow for longer study periods and reduce the risk of any medication-related side effects. In addition, we have refined our surgical methods for minimally invasive spine surgery to perform nerve root injuries and nerve root repairs, and these methods will be used when the addition of stem cell treatments to this new research model. In addition, we have developed and refined a series of imaging and functional outcome measures that are part of our new research tool in the form of improved magnetic resonance imaging techniques for correct identification of spinal cord levels prior to nerve root injury and stem cell injections into the spinal cord. We have also developed urodynamic study protocols as well as electromyography recordings from muscles cells of the pelvic floor and sphincters that are important for bladder and rectal function. These clinically relevant outcome measures are integrated into the research model to help determine the potential benefit from stem cell treatments. A series of 4 research manuscripts related to the present project have been submitted during the first year, and 2 of the manuscripts are presently accepted for publication/In Press.