Do you automatically think donor characterization or cellular characterization, or both? After all, the more we can characterize starting material, annotate the donor and carry out functional assays on the cells, the more you can control variability in the manufacturing process. Fesnak et al., 2019 summarized it well in their publication stating that donor variability drives mononuclear cell product variability, which in turn drives variability in the manufacturing process [1]

Excellos’ Advanced Characterization Program – a portfolio of metrics and assays crucial for understanding the intrinsic factors involved in donor specific cellular proliferation, function, and overall cellular processes. Our characterization program consists of 3 phases: donors, cells and protocols/procedures.


Our data-driven donor characterization and integration system takes donor annotation to the next level. This helps us better predict which donors will best match your development process.  Excellos donors are extensively characterized (functionally, phenotypically and metabolically). Such rigorous annotation is essential in managing the many sources of variability associated with the donor. FACS analysis is performed on the donor cell repertoire to assist with the identification of preferred donors based on client cell requirements (e.g. CD3, CD4/8, NK, CD14, PBMCs).


Excellos performs characterization and tracking of high-quality biospecimens in terms of effector function assessment using the IsoPlexis platform. It is well known that single-cell proteomics will accelerate therapeutic development of cell therapy products by providing crucial functional insights [2]. In addition, metabolic fitness is a key driver of cell function. Excellos has adopted the Agilent Seahorse XF T Cell Metabolic Profiling kit to allow for robust and accurate measurements of glycolytic activities in cell populations, providing a complete picture of cell energy metabolism.


Excellos has optimized protocols for cellular handling, preservation and storage. Minor alterations to protocols can have a large impact, so it is important to manage protocol drift through proper training and monitoring. With freezing, storage and thawing there is a cumulative effect from transient warming events that can potentially cause cell lysis so proper characterization of cells post-thaw is essential.

Excellos undertakes quality monitoring of starting materials, manufacturing intermediates and final products to assure optimal potency of therapy and characterize cAPI content.  (cAPI = cellular Active Pharmaceutical Ingredient).



1. National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Board on Health Sciences Policy; Forum on Regenerative Medicine; Beachy SH, Wizemann T, Hackmann M, editors. Exploring Sources of Variability Related to the Clinical Translation of Regenerative Engineering Products: Proceedings of a Workshop. Washington (DC): National Academies Press (US); 2019 Mar 21. 4, Addressing Variability in Donor Tissues and Cells. 

2. Srivastava S, et al. Abbreviated T-cell activation on the automated CliniMACS Prodigy device enhances bispecific CD19/22 Chimeric Antigen Receptor T-Cell viability and fold expansion, reducing total culture duration. ASH Annual Meeting 2018. Blood 2018; 132: 4551