Optimized reagents for immunopotency assays on mesenchymal stromal cells for clinical use

Abstract

Immunomodulation; Mesenchymal stromal cells; Quality & regulatory compliance

Immunomodulació; Cèl·lules estromals mesenquimàtiques; Qualitat i compliment normatiu

Inmunomodulación; Células estromales mesenquimales; Calidad y cumplimiento normativo

Multipotent mesenchymal stromal cells (MSC) offer new therapeutic opportunities based on their ability to modulate an imbalanced immune system. Immunomodulatory potency is typically demonstrated in vitro by measuring the presence of surrogate markers (i.e., indoleamine-2,3-dioxygenase, IDO; tumor necrosis factor receptor type 1, TNFR1) and/or functional assays in co-cultures (i.e., inhibition of lymphoproliferation, polarization of macrophages). However, the biological variability of reagents used in the latter type of assays leads to unreliable and difficult to reproduce data therefore making cross-comparison between batches difficult, both at the intra- and inter-laboratory levels. Herein, we describe a set of experiments aiming at the definition and validation of reliable biological reagents as a first step towards standardization of a potency assay. This approach is based on the co-culture of Wharton’s jelly (WJ)-derived MSC and cryopreserved pooled peripheral blood mononuclear cells. Altogether, we successfully defined a robust and reproducible immunopotency assay based on previously described methods incorporating substantial improvements such as cryopreservation of multiple vials of pooled peripheral blood mononuclear cells (PBMC) from 5 individual donors that enable a number of tests with same reagents, also reducing waste of PBMC from individual donors and therefore contributing to a more efficient and ethical method to use substances of human origin (SoHO). The new methodology was successfully validated using 11 batches of clinical grade MSC,WJ. Methods described here contribute to minimize PBMC donor variability while reducing costs, streamlining assay setup and convenience and laying the foundations for harmonization of biological reagents usage in standardized immunopotency assays for MSC.

Open Access Funding provided by Universitat Autonoma de Barcelona. This work has been developed in the context of Red Española de Terapias Avanzadas (TERAV, expedient no. RD21/0017/0022) funded by Instituto de Salud Carlos III (ISCIII) in the context of NextGenerationEU’s Recovery, Transformation and Resilience Plan and by the Commission for Universities and Research of the Department of Innovation, Universities, and Enterprise of the Generalitat de Catalunya (2017 SGR 719).