harvesting-embedding-culturing-dorsal-root-ganglia-multi-compartment

Harvesting, Embedding, and Culturing Dorsal Root Ganglia in Multi-compartment Devices to Study Peripheral Neuronal Features

The most common peripheral neuronal feature of pain is a lowered stimulation threshold or hypersensitivity of terminal nerves from the dorsal root ganglia ...

University of Nebraska-Lincoln

Chronic low back pain (LBP) is a leading cause of disability, but treatments for LBP are limited. Degeneration of the intervertebral disc due to loss of neuroinhibitory sulfated glycosaminoglycans (sGAGs) allows nerves from dorsal root ganglia to grow into the core of the disc. Treatment with a decellularized tissue hydrogel that contains sGAGs may inhibit nerve growth and prevent disc-associated LBP.

Injectable decellularized nucleus pulposus tissue exhibits neuroinhibitory properties.

Chronic low back pain is a global socioeconomic crisis and treatments are lacking in part due to inadequate models. Etiological research suggests that the predominant pathology associated with chronic low back pain is intervertebral disc degeneration. Various research teams have created rat models of disc degeneration, but the clinical translatability of these models has been limited by an absence of robust chronic pain-like behavior. To address this deficit, disc degeneration was induced via an artificial annular tear in female Sprague Dawley rats. The subsequent degeneration, which was allowed to progress for 18-weeks, caused a drastic reduction in disc volume. Furthermore, from week 10 till study conclusion, injured animals exhibited significant axial hypersensitivity. At study end, intervertebral discs were assessed for important characteristics of human degenerated discs: extracellular matrix breakdown, hypocellularity, inflammation, and nerve sprouting. All these aspects were significantly increased in injured animals compared to sham controls. Also of note, 20 significant correlations were detected between selected outcomes including a moderate and highly significant correlation ( = 0.59,  < 0.0004) between axial hypersensitivity and disc nerve sprouting. These data support this model as a rigorous platform to explore the pathobiology of disc-associated low back pain and to screen treatments.

Axial hypersensitivity is associated with aberrant nerve sprouting in a novel model of disc degeneration in female Sprague Dawley rats.

Oxidative stress due to excess reactive oxygen species (ROS) is related to many chronic illnesses including degenerative disc disease and osteoarthritis. MnTnBuOE-2-PyP (BuOE), a manganese porphyrin analog, is a synthetic superoxide dismutase mimetic that scavenges ROS and has established good treatment efficacy at preventing radiation-induced oxidative damage in healthy cells. BuOE has not been studied in degenerative disc disease applications and only few studies have loaded BuOE into drug delivery systems. The goal of this work is to engineer BuOE microparticles (MPs) as an injectable therapeutic for long-term ROS scavenging.

Encapsulation of Manganese Porphyrin in Chondroitin Sulfate-A Microparticles for Long Term Reactive Oxygen Species Scavenging.

Low back pain, knee osteoarthritis, and cancer patients suffer from chronic pain. Aberrant nerve growth into intervertebral disc, knee, and tumors, are common pathologies that lead to these chronic pain conditions. Axonal dieback induced by capsaicin (Caps) denervation has been FDA-approved to treat painful neuropathies and knee osteoarthritis but with short-term efficacy and discomfort. Herein, we propose to evaluate pyridoxine (Pyr), vincristine sulfate (Vcr) and ionomycin (Imy) as axonal dieback compounds for denervation with potential to alleviate pain. Previous literature suggests Pyr, Vcr, and Imy can cause undesired axonal degeneration, but no previous work has evaluated axonal dieback and cytotoxicity on adult rat dorsal root ganglia (DRG) explants. Thus, we performed axonal dieback screening using adult rat DRG explants in vitro with Caps as a positive control and assessed cytotoxicity. Imy inhibited axonal outgrowth and slowed axonal dieback, while Pyr and Vcr at high concentrations produced significant reduction in axon length and robust axonal dieback within three days. DRGs treated with Caps, Vcr, or Imy had increased DRG cytotoxicity compared to matched controls, but overall cytotoxicity was minimal and at least 88% lower compared to lysed DRGs. Pyr did not lead to any DRG cytotoxicity. Further, neither Pyr nor Vcr triggered intervertebral disc cell death or affected cellular metabolic activity after three days of incubation in vitro. Overall, our findings suggest Pyr and Vcr are not toxic to DRGs and intervertebral disc cells, and there is potential for repurposing these compounds for axonal dieback compounds to cause local denervation and alleviate pain.

Identification of compounds that cause axonal dieback without cytotoxicity in dorsal root ganglia explants and intervertebral disc cells with potential to treat pain via denervation.

Article	Year
Injectable decellularized nucleus pulposus tissue exhibits neuroinhibitory properties. JOR spine\| PubMed ID: 35386760	2022
Axial hypersensitivity is associated with aberrant nerve sprouting in a novel model of disc degeneration in female Sprague Dawley rats. JOR spine\| PubMed ID: 36203864	2022
Encapsulation of Manganese Porphyrin in Chondroitin Sulfate-A Microparticles for Long Term Reactive Oxygen Species Scavenging. Cellular and molecular bioengineering\| PubMed ID: 36444349	2022
Identification of compounds that cause axonal dieback without cytotoxicity in dorsal root ganglia explants and intervertebral disc cells with potential to treat pain via denervation. PloS one\| PubMed ID: 38696450	2024

Fei San Lee

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