Human dental pulp stem cells exhibit donor- and lineage-specific immunomodulatory effects on macrophages

Human dental pulp stem cells (hDPSCs) are a type of mesenchymal stromal cell (MSC) with significant therapeutic potential, particularly in regenerative medicine and immunomodulation. While their role in tissue repair and inflammation is increasingly recognized, the precise mechanisms and variability of their immunomodulatory actions remain underexplored. Current standard-of-care for inflammatory conditions often involves broad immunosuppressants with systemic side effects, highlighting the need for targeted, cell-based therapies. Understanding the context-dependent nature of hDPSC immunomodulation is crucial for developing consistent and effective cell-based treatments, especially given their emerging use in conditions like psoriasis and oral biofilm infections.

Researchers investigated the immunomodulatory capacity of hDPSCs from three independent human donors on macrophages. They differentiated macrophages from THP-1 and U-937 monocytic cell lines and established co-culture systems with hDPSCs. The primary endpoints included assessing cytokine secretion profiles using multiplex immunoassays and evaluating macrophage surface marker expression via flow cytometry. Additionally, they examined transcriptional changes in inflammation-related genes within hDPSCs upon interaction with macrophages, providing insights into the cellular responses during co-culture.

Co-culture experiments revealed significant donor- and lineage-specific modulation of key cytokines by hDPSCs. Specifically, they observed altered secretion profiles for TNF-α, IL-10, IL-6, IL-1β, CXCL10, and IL-1RA. This indicates a nuanced and variable immunomodulatory response depending on the hDPSC donor and the macrophage lineage. Despite these cytokine shifts, surface marker analysis indicated minimal changes in macrophage polarization, suggesting that hDPSCs primarily influence macrophage function through secreted factors rather than direct phenotypic shifts. Importantly, hDPSCs themselves exhibited transcriptional changes in inflammation-related genes when interacting with macrophages, highlighting a reciprocal cellular communication. > The study's most critical finding is that hDPSC immunomodulatory activity is highly context-dependent and donor-specific, underscoring significant variability in their therapeutic potential.