Mesenchymal stromal cells (MSCs) are increasingly employed in neurological clinical trials, yet their behavior within the cerebrospinal fluid (CSF) environment is poorly understood. This study included both in vitro transcriptomic analysis of MSCs in a high-fidelity artificial CSF following good manufacturing process (GMP) protocols and in vivo analysis of growth factor levels in CSF in a Phase 1 ALS clinical trial where MSCs were administered intrathecally.

MSCs have multiple therapeutic properties, therefore are an attractive treatment modality for neurodegenerative diseases. The CSF compartment presents unique challenges to MSCs, including lower oxygen and protein concentration, and it is unclear if MSCs maintain their therapeutic properties under these stressors. Prior work has explored hypoxia and serum deprivation on MSCs, however these studies have limited translation to clinical trials because of use of research-grade reagents.

Adipose-derived MSCs were cultured in complete media (CM), a serum-deprived platelet lysate free media (PLF), human CSF, and artificial CSF for histological, metabolic, and transcriptomic analysis. In a Phase 1 clinical trial, autologous adipose-derived MSCs were intrathecally administered to ALS patients with multiple doses studied (1 x 10⁷, 5 x 10⁷, or 10 x 10⁷ cells) and CSF collected for analysis.

In vitro comparisons of MSCs grown in CM, PLF, human CSF and artificial CSF demonstrate that CSF conditions induce expression of genes associated with angiogenesis, immunomodulation, and nutritional growth factors. In the clinical trial, MSCs significantly increase expression of multiple growth factors (VEGF, PIGF, and GDF-15) at 1 week post-injection.

This is the first study examining MSC behavior in high-fidelity GMP-grade artificial CSF culture condition, and the human clinical trial data support the in vitro findings. This project demonstrates that MSCs exert therapeutic effects in the CSF compartment, with high doses (10 x 10⁷ cells) offering the greatest benefit.