In Vitro Models of Spinal Cord Injury

Abstract

Living organisms are extremely complex functional systems. At present, there are many in vivo models of spinal cord injury (SCI) that allow the modeling of any type of central nervous system (CNS) injury, however, with some disadvantages. The production of injury models can be a highly invasive and time-consuming process and requires high technical requirements, and costly financial issues should also be taken into account. Of course, a large number of animals have been used to obtain the relevant data of statistical significance. All of these aspects can be reduced by carrying out experiments in in vitro conditions. The primary advantage of in vitro method is that it simplifies the system under study. There are two major groups of in vitro model in use: cell culture and organotypic slice (OTS) culture. OTS is an intermediate system of the screening of in vitro cell culture and animal models and represents the in vitro system preserving the basic tissue architecture that able to closely mimic the cellular and physiological characteristics in vivo. In vitro models are the preferred methods for the study of acute or subacute pathophysiology after a trauma stimulus, enabling precise control on the extracellular environment, easy and repeatable access to the cells.

Targeting Aquaporin-4 Subcellular Localization to Treat Central Nervous System Edema

“…The relative increase in tonicity that leads to CNS edema can be modeled by hypotonic treatment or hypoxic exposure of primary astrocytes (Orellana et al, 2010;Slovinska et al, 2016;Yu et al, 1989). To date, we have used a hypotonicity model to study AQP4 translocation (Kitchen et al, 2015;Salman et al, 2017a).…”

Injectable Scaffold-Systems for the Regeneration of Spinal Cord: Advances of the Past Decade

“…The commonly used in vitro cell culture models of SCI include i) primary isolated neurons, oligodendrocytes, astrocytes, or microglia cells; ii) co-culture of neuronal cells with different cell types, which are present in the glial scar; iii) co-cultivation with meningeal cells in in vitro scar formation model, called scratch model; iv) rat spinal cord cells onto a confluent monolayer of neurosphere derived astrocytes for investigating the CNS axonal myelination; v) neurite outgrowth assays for the phenotypic expression of regeneration progress 87 .…”

“…Unfortunately, animal studies offer complexity, which is very difficult to model in vitro, and high variability, which prevents reproducible studies 88,89 . For this reason, organotypic cultures of spinal cord explants could be an option to obtain reproducible results after a contusion injury 87,90 . The spinal cord explants are cut to obtain slices, called organotypic slices (OTSs), that preserve the basic structural and connective organization of their original tissue (organotypic).…”

“…Organotypic spinal cord slice (OTS-SC) are generally cultivated on a semi-porous membrane at the airmedium interface to allow nutrition and gas exchanges, under appropriate conditions the slices can survive for a week to months 87 .…”

“…The OTS-SC model is suitable for axonal growth evaluation because the typical ventrodorsal polarity of the SC is maintained after a culture period of 2 weeks, and intrinsic spinal cord axons formed a strong fiber tract extending along the longitudinal axis of the slice 87,90 (Figure 9). A well defined in vitro evaluation could contribute to understanding the results of in vivo analysis, for example, Basso, Beattie, and Bresnahan locomotor score (BBB), ladder climbing test, electrophysiological recordings such as the rate-dependent depression (RDD) of the Hoffmann's reflex (H-reflex), defined as "the decrease in reflex magnitude relative to repetition rate" 3 , suitable for evaluating sensorimotor improvements and spasticity.…”