For someone without a severe spinal cord injury (SCI), trying to wrap your head around what it would be like to experience is next to impossible. While most of us might focus on the mobility difficulties such a condition may cause, it’s easy to forget that many who experience paralysis also lose sensation in parts of their body — robbing them of their sense of touch.

In a new piece of research, investigators from University of California, Los Angeles look to have taken a big step in helping with this by coaxing stem cells to become sensory interneurons for the first time. The protocol could be a crucial advance in stem cell-based therapies able to restore sensation in paralyzed individuals who have lost feeling in parts of their body.

“Our work is exciting because we are the first to apply the right signals that tell stem cells how to become a type of spinal sensory neurons, the neurons that normally reside in the spinal cord that let you experience and react to the environment,” Samantha Butler, a UCLA associate professor of neurobiology and part of the Broad Stem Cell Research Center, told Digital Trends.

“Specifically,” Butler continued, “these are the neurons that let you feel touch, and — something more mysterious — [establish] the position of your body in space. ‘Proprioception’ is a super power you didn’t know you had. Your spinal cord knows where your body is at all times, so that your legs don’t knock into each other as you walk, for example, or you hold yourself upright without thinking about it. If you lose proprioception you can still do these things, but it is extremely difficult: you need to be consciously willing yourself to perform the right movement task at all times.”

In previous work, Butler and her colleagues discovered how signals from a family of proteins called bone morphogenetic proteins (BMPs) influence the development of sensory interneurons in chicken embryos. In their new project, they added a specific bone morphogenetic protein called BMP4, along with another signaling molecule called retinoic acid, to human embryonic stem cells. The results were a mixture of two types of sensory neurons, providing proprioception and also enabling people to feel a sense of pressure.

The group is currently implanting these new sensory interneurons into the spinal cords of mice to discover whether they will integrate into the nervous system and become fully functional. Their research was recently published in the journal Stem Cell Reports.

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