Wharton's Jelly Mesenchymal Stem Cells Exosomes and Conditioned Media Increased Neutrophil Lifespan and Phagocytosis Capacity

Neutrophils are the first cells involved in inflammation and pathogen elimination, but they have a short lifespan. So, strategies for enhancing neutrophil lifespan and activities can be useful in many situations such as patients with immunodeficiencies. Previous researches demonstrated that mesenchymal stem cell (MSC) has anti-apoptotic effects on neutrophils. These multipotent cells have immunomodulatory properties and can be isolated from different tissues. MSCs isolated from Wharton's jelly (WJ-MSCs), a mucosal connective tissue of the umbilical cord, may be better candidates than MSCs obtained from bone marrow or adipose tissue, because WJ-MSCs are younger and protected from damages that are resulted from aging, environmental toxins, and diseases. In addition, they have high proliferative capacity, easier accessibility, and more abundance. It was shown that following in vitro expansion, they are more effective than other sources of MSCs. Cell to cell contact or secretion of soluble factors and exosomes are the main approaches of MSCs in applying their effects. Exosomes and conditioned media (CM) were prepared from WJ-MSCs. Then, neutrophils were isolated and cultured with medium, CM, or exosomes. Then, neutrophil respiratory burst, apoptosis, and phagocytosis capacity were assessed by NBT assay, Annexin V-PI method, and Giemsa staining, respectively. Both treatments improved neutrophil lifespan and phagocytosis. Only MSC-CM could enhance neutrophil respiratory burst. This research demonstrated that MSC-exosomes and CM have protective effects on neutrophil function and lifespan. It can be concluded that MSC mediators can be responsible factors for protective functions of MSCs on neutrophils.