TY  - GEN
TI  - Differentiation and characterization of human stem cell-derived nociceptors and comparison to human and mouse dorsal root ganglia tissue
A1  - Rostock, Charlotte
N2  - The capability to sense and transduce environmental as well as internal sensory stimuli, such as touch, pain or muscle tension, is a fundamental process required for cell survival and the avoidance of tissue damage of the body. Vertebrates can detect these stimuli via specialized cells in the peripheral nervous system - the somatosensory neurons. It is well known that the peripheral nervous system consists of many different types of neurons, but how they are generated and how they establish their functional abilities is at present not fully understood. 
Although pain sensation represents an adaptive alarm system detecting signals that are potentially harmful to the body, persistent pain is a maladaptive false alarm and nowadays clinicians have only few, if any, effective means to medicate chronic pain. Therefore, it is indispensable to get a more detailed understanding of how pain signals are transmitted and how human pain-sensitive neurons are established, given that most of the current knowledge about pain or pain sensation is based on animal studies. Although animal models provided a basis for research about causes, onset and course of pain diseases, there is more and more evidence that the translation of these findings to human patients is more challenging than expected.
Therefore, the aim of this Ph.D. thesis was to establish a differentiation protocol for the generation of functional human embryonic stem cell (hESC)-derived nociceptors. I found that a transient overexpression of the bHLH transcription factor neurogenin 1 (NGN1), known to induce neurogenesis and to mediate the differentiation of nociceptive neurons in mice, was sufficient to differentiate progenitor cells of the peripheral nervous system (PNS) into primary sensory neurons with a nociceptive phenotype. Differentiated cells were analyzed and characterized by using Ca2+-imaging, immunohistochemistry, in situ hybridization, quantitative RT-PCR and electrophysiological recording techniques, confirming their nociceptor-like properties. To validate whether hESC-derived nociceptors are physiologically relevant and can reflect the in vivo equivalent, we compared them to human post-mortem DRG tissue where we found a similar marker gene profile. A comparative study that I carried out using human and mouse post-mortem DRG tissue highlighted molecular differences of murine and human sensory neurons that need to be considered when using the mouse as a model system for the development of new analgesic drugs.
Furthermore, we were also interested in exploring the role of PIEZO2 in sensory neurons. Recent findings in rodents identified PIEZO2, a large transmembrane protein, as a main transducer of innocuous mechanical stimuli, and we confirmed that PIEZO2 is also required for mechanotransduction in human stem cell-derived touch receptors. However, it is so far uncertain whether PIEZO2 also plays a role in transducing noxious mechanical stimuli to trigger sensation of pain. Rapidly-adapting, mechanically-activated currents (at least those conventionally recorded when using a nanomotor-driven stimulus probe) appeared to be absent in PIEZO2-knockout (KO) nociceptors, indicating that PIEZO2 is also required for mechanotransduction in stem cell-derived nociceptors. Additionally, I also aimed to identify accessory proteins of PIEZO2 that are involved in human PIEZO2-mediated sensory mechanotransduction, by generating a PIEZO2-tagged hESC line. 
The outcome of this study would allow us to identify differences and similarities between human and mouse nociceptors and furthermore, to use this differentiation protocol as a basis for the generation of other distinct human nociceptive subpopulations, to finally provide a model system to study human pain and pain transduction in vitro.
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/24227/
Y1  - 2018///
ID  - heidok24227
AV  - public
ER  -