Urine stem cells are equipped to provide B cell survival signals

The interplay between mesenchymal stem cells (MSCs) and immune cells has been studied for MSCs isolated from different tissues. However, the immunomodulatory capacity of urine stem cells (USCs) has not been adequately researched. The present study reports on the effect of USCs on peripheral blood lymphocytes. USCs were isolated and characterized before coculture with resting and with anti-CD3/CD28 bead stimulated lymphocytes. Similarly to bone marrow mesenchymal stem cells (BM-MSCs), USCs inhibited the proliferation of activated T lymphocytes and induced their apoptosis. However, they also induced strong activation, proliferation, and cytokine and antibody production by B lymphocytes. Molecular phenotype and supernatant analysis revealed that USCs secrete a range of cytokines and effector molecules, known to play a central role in B cell biology. These included B cell-activating factor (BAFF), interleukin 6 (IL-6) and CD40L. These findings raise the possibility of an unrecognized active role for kidney stem cells in modulating local immune cells. © AlphaMed Press 2021 SIGNIFICANCE STATEMENT: The active role of stem cells in maintaining tissue homeostasis has been well documented, particularly their ability to modulate the local immune response. This study on the immunomodulatory properties of urine stem cells (USCs) shows that, like mesenchymal stem cells, they are capable of modulating immune cells. However, the authors uncovered an unknown capacity of USCs, residents of the kidney, to promote B lymphocyte functions, which could potentially change our understanding of the kidneys' normal immune environment and immune-mediated nephropathy. Furthermore, the authors' findings reveal a new possible therapeutic use of USCs as an immune adjuvant with clinical implications.