Painful diabetic neuropathy (PDN) is one of the most common and intractable complications
of diabetes. PDN is characterized by small-fiber degeneration and neuropathic pain.
Uncovering the mechanisms underlying neurodegeneration in PDN remains a major challenge
to finding effective and disease-modifying therapy. Keratinocytes are closely juxtaposed
to cutaneous nerve terminals potentially enabling communication between keratinocytes
and cutaneous afferents. The aim of this study is to explore mechanisms by which keratinocytes
communicate with cutaneous afferents and how this communication impacts DRG neuron
axonal degeneration underlying neuropathic pain in PDN. We have established a Xona
microfluidic coculture device to compartmentalize murine DRG neurons and keratinocytes
to model the skin in vitro and investigated the effects of activated K14 keratinocytes
on DRG neurite outgrowth and neuron excitability. We found that cocultured DRG neurites
grew towards keratinocytes within 7 days. Additionally, we found that once the neurites
grew in the microchannels, they are unable to turn back and continue to grow into
the adjacent compartment, where they form connections with cultured keratinocytes.
Using electrophysiological and calcium images studies on these microfluidic devices
we revealed a dynamic interplay between the neuronal activity and keratinocytes. For
example, we have used this system to test the effects on DRG neurons neurite outgrowth
and excitability upon application different stimuli including class III semaphorins
and chemokines (neutrophil chemo-attractant genes such as CXCL10), known to be secreted
by keratinocytes. More recently we have used this platform to study interaction between
human iPSCs derived DRG neurons and human keratinocytes. In conclusion, this platform
can be used to explore mechanisms by which keratinocytes communicate with cutaneous
afferents and how this communication impacts DRG neuron axonal degeneration underlying
neuropathic pain in PDN. Grant support from 1R01AR77691-01.
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