Potency Analysis of Mesenchymal Stromal Cells Using a Phospho-STAT Matrix Loop Analytical Approach

Area of Science:

• Cellular Biology
• Immunology
• Biotechnology

Background:

• Mesenchymal stromal cells (MSCs) are crucial in advanced clinical trials, necessitating robust potency assays.
• Current assays lack standardized methods for evaluating MSC function, particularly their secretome interactions.

Purpose of the Study:

• To develop and validate an assay matrix approach for assessing MSC potency.
• To investigate the role of signal transducer and activator of transcription (STAT) phosphorylation in MSCs upon stimulation by co-cultured peripheral blood mononuclear cell (PBMC) secretomes.

Main Methods:

• Developed an assay matrix using phosflow technology to measure STAT1, STAT3, STAT4, STAT5, and STAT6 phosphorylation in MSCs.
• Utilized secretomes from heat-inactivated (HI) MSCs and activated PBMCs as internal references.
• Compared MSCs derived from human bone marrow, adipose tissue, and umbilical cord.

Main Results:

• Live MSC secretomes co-cultured with activated PBMCs downregulated STAT1 and STAT3 phosphorylation on MSCs.
• Secretomes from HI-MSCs or PBMCs alone did not induce this downregulation.
• MSCs from different sources (bone marrow, adipose, umbilical cord) showed comparable STAT1 and STAT3 modulation.
• STAT1 and STAT3 phosphorylation levels correlated with allogeneic T-cell suppression.

Conclusions:

• The combined secretome interaction between MSCs and PBMCs determines MSC potency as both generator and sensor.
• The comparative phosphomatrix approach provides a robust platform for predictive potency analysis of MSCs.
• This assay advances the definition of MSC potency for clinical trial applications.