# Modeling Spinal Cord Injury in a Dish with Hyperosmotic Stress: Population-Specific Effects and the Modulatory Role of Mesenchymal Stromal Cell Secretome

## TL;DR

This study introduces a new in vitro model for spinal cord injury using hyperosmotic stress and shows that the secretome of human stem cells can protect neurons and reduce injury markers.

## Contribution

The first use of sorbitol as a hyperosmolar stressor to model SCI and the demonstration of hASC secretome's protective effects in this context.

## Key findings

- Hyperosmotic stress via sorbitol caused a 65% reduction in cell viability, mimicking SCI pathophysiology.
- hASC secretome preserved metabolic viability and reduced β-APP expression in neurons.
- Transcriptomic analysis revealed enrichment in cell proliferation and cycle progression pathways after hASC treatment.

## Abstract

Innovations in spinal cord injury (SCI) models are crucial for developing effective therapies. This study introduces a novel in vitro SCI model using cultures of primary mixed spinal cord cells from rat pups, featuring key spinal cord cell types. This model offers distinct advantages in terms of feasibility, reproducibility, and cost-effectiveness, requiring only basic cell culture equipment. Following hyperosmotic stress via sorbitol treatment, the model recapitulated SCI pathophysiological hallmarks, with a 65% reduction in cell viability and gradual cell death over 48 h, making it ideal for evaluating neuroprotective agents. Notably, the human adipose tissue stem cell (hASC) secretome provided significant protection: it preserved metabolic viability, reduced β amyloid precursor protein (β-APP) expression in surviving neurons, and modulated the shift in the astrocytic morphotype. A transcriptomic profile of the effect of the hASC secretome treatment showed significant functional enrichments related to cell proliferation and cycle progression pathways. In addition to supporting the use of the hASC secretome as a therapy for SCI, this study is the first to use sorbitol as a hyperosmolar stressor to recapitulate key aspects of SCI pathophysiology. Thereby, this model can be used as a promising platform for evaluating therapeutic agents targeting neuroprotection and neuroregeneration, offering outputs related to cell death, neuronal stress, and protection, as well as induction of glial reactivity.