Human In-Vivo Bioassay for the Tissue-Specific Measurement of Nociceptive and Inflammatory Mediators

Summary

A technique is presented for the in-vivo collection of interstitial fluid samples from pertinent tissue sites (here, experimentally inflamed skin) for the measurement of biochemicals mediating pain and inflammation.

Abstract

This in-vivo human bioassay can be used to study human volunteers and patients. Samples are collected from pertinent tissue sites such as the skin via aseptically inserted microdialysis catheters (Dermal Dialysis, Erlangen, Germany). Illustrated in this example is the collection of interstitial fluid from experimentally inflamed skin in human volunteers. Sample collection can be combined with other experimental tests. For example, the simultaneous assessment of locally released biochemicals and subjective sensitivity to painful stimuli in experimentally inflamed skin provides the critical biochemical-behavioral link to identify biomarkers of pain and inflammation. Presented assay in the living human organism allows for mechanistic insight into tissue-specific processes underlying pain and/or inflammation. The method is also well suited to examine the effectiveness of existing or novel interventions – such as new drug candidates – targeting the treatment of painful and/or inflammatory conditions. This article will provide a detailed description on the use of microdialysis techniques for collecting interstitial fluid from experimentally inflamed skin lesion of human study subjects. Interstitial fluid samples are typically processed with aid of multiplex bead array immunoassays allowing assaying up to 100 analytes in samples as small in volume as 50 microliters.

Protocol

Induction of experimental inflammation: A first-degree sunburn is induced in non-tanned skin of a thigh with aid of a calibrated, ultraviolet B source (Saalmann Multitester SBB LT 499, Saalmann GmbH, Hereford, Germany). The sunburn is induced 24 hours before starting a microdialysis experiment by applying three times the amount of UVB light necessary to cause complete reddening of exposed skin, or three times the minimal erythemal dose (MED). The MED is determined in each subject before study initiation. Accur…

Discussion

The combined use of microdialysis techniques and multiplex immunoassay technology is a valuable real-time, in-vivo human bioassay providing insight into biochemical events in tissue of interest. Combined with behavioral tests such as pain tests, the method allows studying the complex interactions of biochemicals mediating pain and inflammation. The method is promising for 1) identifying tissue specific biomarkers mediating pain and inflammation, 2) providing mechanistic insight into the pathology of inflammatory and chro…

Materials

Material Name	Tipo	Company	Catalogue Number	Comment
Microdialysis catheter	Tool	Dermal Dialysis	NA
Pump 22	Tool	Harvard Apparatus	552219
Saalmann Multitester SBB LT 400	Tool	Saalmann GmbH	NA
RM-12 IP-65 Radiometer	Tool	Dr. Grobel UV Elektronik GmbH	82120000/81112100
Complete Proteinase Inhibitor	Reagent	Roche Bioscience	11836145001
Microcent tube	Tool	E&K Scientific	380150-X
Albumin 5%	Reagent	ZLB Behring	NA
Lactated Ringer	Reagent	Hospira Inc	NA
Xylocaine-MPF	Outro	Astra Zeneca	NA
Syringe 1mL	Tool	Becton Dickinson Co	309602