The Sense of Feeling Restored

Sam Neff ’21 / Biological Sciences, News, Winter 2018 / January 21, 2018

Interneurons in the mouse cerebral cortex expressing the green fluorescent protein.
(Source: Wikimedia Commons)

A recent bout of stem cell research has yielded a significant achievement: the generation of certain interneurons, ones that are involved in producing the sense of touch, from human embryonic stem cells. Researchers at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA conducted the study (1).

The particular types of interneurons generated are found in the spinal cord and process information from principal sensory neurons throughout the body. These principal sensory neurons directly receive external or internal signals, such as the presence of heat or the touch of some object. The interneurons are essential for integrating the peripheral nervous system, which detects signals and produces movement, with the central nervous system, composed of the brain and spinal cord: the centers for processing and sending out information to the rest of the body (1).

The researchers grew these interneurons in the laboratory by subjecting them to a specific type of protein, bone morphogenetic protein 4 (BMP-4), and the signaling molecule retinoic Two types of neurons were generated: 1) the dI1 neuron, which confers the sense of where the body is in space; and 2) the dI3 neuron, which allows for the feeling of pressure (1,2).

This method of neuron growth was first used on embryonic stem cells, but was later applied to adult stem cells, which are present in small amounts in certain body regions. The same types of interneurons were generated in both test groups (1). Therefore, it is possible to use one’s own stem cells to build neurons.

Neuron generation occurring within one’s own body rather than inside a laboratory poses an interesting scenario. The creation of biological scaffolds that mimic the body’s interior and create an environment for cell growth, is a primary objective of tissue engineering (3). In this case, a suitable scaffold could potentially be created that incorporates stem cells, either adult or embryonic, and other necessary materials such as bmp4, retinoic acid, allowing for neuronal growth. Once generated, the new interneurons will supposedly form synapses, or connections, with already existing neural cells. Further research is required to examine whether such integration occurs, and its mechanisms.

The fact that adult stem cells are suitable for neuronal growth is a key accomplishment of this study, especially since ethical controversy exists over the use of embryonic stem cells. The use of adult stem cells would allow scientists to not only avoid ethical difficulties but to also more efficiently apply findings in real medical situations.

If these interneurons can be grown and integrated within the human nervous system, an extensive array of applications are possible, including restoring feeling to those suffering from paralysis, and production of prosthetics that allow finer control over one’s movement. The senior author of the study, Samantha Butler, remarked, “To walk, you need to be able to feel and sense your body in space; the two processes really go hand in glove.” If this research is taken to such conclusions, those with the aforementioned disabilities could lead even more active lives.

References

(1) University of California – Los Angeles Health Sciences. (2018, January 11). “Scientists make cells that enable the sense of touch: Researchers are the first to create sensory interneurons from stem cells.” ScienceDaily. ScienceDaily, Retrieved 13 January 2018 from <www.sciencedaily.com/releases/2018/01/180111141555.htm>.

(2) Sandeep Gupta, Daniel Sivalingam, Samantha Hain, Christian Makkar, Enrique Sosa, Amander Clark, Samantha J. Butler. (2018, January 11). “Deriving dorsal spinal sensory interneurons from human pluripotent stem cells.” Stem Cell Reports, Elsevier. Retrieved 14 January 2018 from <http://www.sciencedirect.com/science/article/pii/S221367111730560X>

(3) Anuradha Subramanian, Uma Maheswari Krishnan, Swaminathan Sethuraman, (2009, November 25). “Development of biomaterial scaffold for nerve tissue engineering: Biomaterial mediated neural regeneration.” Journal of Biomedical Science. National Center for Biotechnology Information. Retrieved 13 January 2018 from <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2790452/>