Targeting chronic neuropathic pain biomarkers for drug development

Introduction: Chronic neuropathic pain is pathologically complex, often refractory to conventional pharmacotherapy and is poorly understood. It is estimated that almost 1 in 5 adults experience moderate-severe pain and often receive ineffective or suboptimal treatment. With a growing ageing population with numerous comorbidities, this is fast becoming a significant healthcare issue that requires urgent attention.The generation of an in vitro disease model and identification of disease biomarkers can not only provide a tool for early diagnosis, but can also facilitate the identification of novel drug targets for the potential treatment of CNP.

Methods: To identify these novel biomarkers/drug targets for CNP treatment we sourced a commercially obtained (ProteoGenex) group of CNP and control group samples (n=20) and employed a combination of quantitative PCR and Affymetrix array systems to locate gene susceptibility links (RNA), and HPLC/Mass Spectrometry for plasma analyses in both human and animal systems. Stem cell systems will be generated by transduction of skin biopsies of CNP subtypes (20 patients) using the CytoTune Sendai 2.0 viral reprogramming kit encoding four transcription factors (KLF4, c-MYC, OCT4, SOX2). These cells will then be characterised at the molecular level through immunostaining of iPSC markers (TRA-1-60/CD44),karyotyping and embryoid body formation to determine pluripotency.

Results: Transcriptomic analysis of commercially available RNA for CNP identified 869 significant differentially expressed genes. A subset of candidates identified were selected based on relevance to CNP and associated co-morbidities, gene function and statistical significance. Candidate genes encompasses genes relating to inflammation, neuronal injury, apoptosis, pain sensitivity, stress and immune response including DFFA, ELF3 and MDM1. To investigate these candidates further we are developing a stem cell model systems of CNP.

Discussion: The establishment of CNP patient-specific stem cell models will support the identification of novel susceptibility targets and validate previously found pain-related genes, allowing us to elucidate the underlying mechanisms within CNP. Further differentiation of derived stem cells into pain-relevant neuronal cell types, including dorsal root ganglion neurons, will categorize variations through analysis of cell functioning such as neuron firing electrophysiology between CNP groups. This will offer a platform for in vitro screening for pharmaceutical intervention of novel analgesic targets.