Nature Neuroscience's single-cell mass spectrometry flow cytometry reveals the development of the somatosensory system

Humans perceive tactile information, including pressure, pain, itching, temperature, vibration, and movement, thanks to a complex network
of neurons located in the brain and spinal cord.
This network, known as the somatosensory system, is now known to consist of several distinct groups of
mature neurons located in the dorsal root ganglion (DRG) and spinal cord.

While past studies in mice have identified specific populations of sensory neurons and their possible functions, little is known about how these neurons develop and assume different functions over time
.
A better understanding of these processes will ultimately help glean valuable insights into the neural basis of some developmental sensory disorders, such as congenital pain insensitivity with anhidrosis (a disorder characterized by the inability to feel pain and temperature) and autism spectrum disorder (ASD).

Researchers from the Charlottesville-based College of Arts and Sciences and the University of Virginia recently conducted a study that explored the changes
that occur during the development of the body's sensory system using a technique called single-celled giant cytometry.
Their findings, published in the journal Nature Neuroscience, shed new light on
the maturation and differentiation of somatosensory neurons in DRG, the dorsal root of spinal nerves.

"Our recent study builds on decades of work related to the development of somatosensory nervous systems," said
Christopher Deppmann, one of the researchers who conducted the study.
"We want to show that an analysis that would normally take years to complete can now be done
in a matter of weeks or months.
"

Deppmann and his colleagues analyzed the DRG of developing male and female mice, collecting samples from them daily from before birth to the fourth day of life
.
They analyzed the samples using single-cell mass spectrometry flow cytometry, a powerful technique
for assessing the unique characteristics of individual cells.
The technique allowed them to measure nearly 3 million cells and analyze their characteristics
.

Deppmann explains: "We optimized mass spectrometry cytometry, a relatively new technique that can measure proteins in millions of nerve cells, providing unprecedented molecular and temporal resolution
for major and rare cell types.
Our findings demonstrate for the first time the concept of large-scale cytometry in neurons, which should open the door to proteomic analysis in other regions of the
nervous system.
" ”

Through their analysis, Deppmann and his colleagues were able to describe 30 molecularly distinct somatosensory glial states and 41 neuronal states, spanning different developmental stages
in the samples they collected.
They then also identified neurotrophic factor receptors (i.
e.
, neurotrophic factors bound to growth factor receptors) that may play a key role in the differentiation of somatosensory cells (i.
e.
, determine their function after maturation).

Interestingly, the researchers found that their findings differed somewhat from previous studies
using RNA analysis methods.
This underscores the importance of collecting protein-level measurements to better understand functional cell state and neuronal development
over time.

The results collected by Deppmann and his colleagues provide new valuable insights
into the maturation of somatosensory cells in DRG and their unique developmental stages.
In the future, their work could facilitate more applications
of single-cell mass spectrometry flow cytometry for the analysis of somatosensory tissue.

"We now plan to use the same approach presented in our paper to address fundamental questions related to the development of sensory neurons (e.
g.
, male/female differences, effects of inflammatory signals) and begin studying other developmental maps (e.
g.
, the brain)," Deppmann added
.