Equine mesenchymal stem cells inhibit T cell proliferation through different mechanisms depending on tissue source

Area of Science:

• Veterinary immunology
• Regenerative medicine
• Cell biology

Background:

• Mesenchymal stem cells (MSCs) are utilized in clinical trials for inflammatory and immune-mediated diseases.
• Equine MSCs from bone marrow (BM), adipose tissue (AT), cord blood (CB), and umbilical cord tissue (CT) inhibit lymphocyte proliferation and inflammatory cytokine production.

Purpose of the Study:

• To investigate if equine MSCs inhibit T cell proliferation via secreted mediators.
• To determine if MSCs from different tissue sources employ unique mechanisms to suppress T cell proliferation.

Main Methods:

• Equine MSCs were stimulated, and their effects on T cell proliferation were assessed.
• Interleukin-6 (IL-6), nitric oxide (NO), and prostaglandin E2 (PGE2) were inhibited to evaluate their roles in MSC immunomodulation.
• Mechanisms of lymphocyte modulation (cell cycle arrest vs. apoptosis) were analyzed based on MSC tissue source.

Main Results:

• Inhibition of IL-6 or NO did not alter the immunomodulatory effect of MSCs on T cells.
• Inhibition of PGE2 restored T cell proliferation and altered cytokine profiles (TNF-α, IFN-γ, IL-10).
• Solid-tissue MSCs (AT, CT) induced lymphocyte apoptosis, while blood-derived MSCs (BM, CB) induced cell cycle arrest.

Conclusions:

• Equine MSCs utilize both overlapping and distinct mechanisms to modulate immune cell function, influenced by their tissue source.
• Prostaglandin E2 (PGE2) plays a significant role in the immunomodulatory effects of equine MSCs.
• The tissue source of equine MSCs is a critical factor that may determine their therapeutic efficacy in immunomodulatory applications.