Stem Cell Therapies for Neuropathic Pain
Progress on the utility of cell based therapies for neuropathic pain research is dependent upon the application of appropriate experimental animal models of peripheral and central nerve lesions.
There are two broad groups of experimental animal models of neuropathic pain: those that localise the lesion e.g. dorsal root ganglion lesion, peripheral nerve lesion, spinal cord lesion, and dorsal and ventral root lesion; and those that describe the type of lesion e.g. transection, tumour cell invasion or laser radiation, cryoneurolysis, crush, stimulation of perineuronal inflammation, and tight or loose ligature. However, no single animal model entirely recaptures the full range of neuropathic pain mechanisms.
In animal models the assessment and quantification of neuropathic pain by direct evaluation is not feasible. Rather subjectively, most data obtained using animal models have relied on the use of evoked pain-related behaviours such as withdrawal responses as surrogate markers for neuropathic pain. Leading on from this, complexities regarding assessing neuropathic pain in animal models are further exemplified by attempts to extrapolate and identify relevant markers for spontaneous pain. This is particularly problematic for patients with neuropathic pain but rather difficult to measure in rodents. Surrogate indicators include: changes in general innate behaviours such as locomotion, burrowing, digging, excessive grooming and nesting; and more complicated paradigms using Pavlovian conditioning methods such as conditioned place preference and aversion. Notwithstanding these methods, laboratory tools for objectively assessing neuropathic pain in animal models are available and utilise two surrogate markers, namely: thermal hyperalgesia using the acetone test; and mechano-allodynia using the von Frey test.
Peripheral and Central Injury Models
Progress on the utility of cell based therapies for neuropathic pain research is dependent upon the application of appropriate experimental animal models of peripheral and central nerve lesions.
There are two broad groups of experimental animal models of neuropathic pain: those that localise the lesion e.g. dorsal root ganglion lesion, peripheral nerve lesion, spinal cord lesion, and dorsal and ventral root lesion; and those that describe the type of lesion e.g. transection, tumour cell invasion or laser radiation, cryoneurolysis, crush, stimulation of perineuronal inflammation, and tight or loose ligature. However, no single animal model entirely recaptures the full range of neuropathic pain mechanisms.
In animal models the assessment and quantification of neuropathic pain by direct evaluation is not feasible. Rather subjectively, most data obtained using animal models have relied on the use of evoked pain-related behaviours such as withdrawal responses as surrogate markers for neuropathic pain. Leading on from this, complexities regarding assessing neuropathic pain in animal models are further exemplified by attempts to extrapolate and identify relevant markers for spontaneous pain. This is particularly problematic for patients with neuropathic pain but rather difficult to measure in rodents. Surrogate indicators include: changes in general innate behaviours such as locomotion, burrowing, digging, excessive grooming and nesting; and more complicated paradigms using Pavlovian conditioning methods such as conditioned place preference and aversion. Notwithstanding these methods, laboratory tools for objectively assessing neuropathic pain in animal models are available and utilise two surrogate markers, namely: thermal hyperalgesia using the acetone test; and mechano-allodynia using the von Frey test.
Source...