Interleukins Profiling in Umbilical Cord Mesenchymal Stem Cell-Derived Secretome.

Background: Umbilical cord mesenchymal stem cells (UC-MSCs)-derived secretome is currently used in regenerative therapy. MSCs are believed to secrete a wide spectrum of bioactive molecules which give paracrine effects in immunomodulation and regenerative capacities. One group that was found in secretome is interleukins (ILs), a cytokine that plays an essential role in the process of proliferation, differentiation, maturation, migration, and adhesion of immune cells. However, as there are many types of ILs, the profile of ILs in the UC-MSCs-derived secretome has been limitedly reported. Therefore, in this study, we would like to profile and detect the interleukin concentration secreted by UC-MSCs.

Methods: UC-MSCs-derived secretome was collected from UC-MSCs passage 5 after 24- and 48-hour incubation (n=9). Secretome was filtered using 0.2 µm and stored at -80°C for further detection. All samples were normalized before the interleukin (IL-2, IL-4, IL-6, IL-9, IL-10, IL-12, IL-17A) detection using a MACSPlex Cytokine Kit.

Results: The IL-6 has the highest concentration among other interleukins in both groups and increases significantly (p<0.003) after incubation for 48 hours. The pro-inflammatory factors are decreasing while anti-inflammatory factors are increasing after 48-hour incubation.

Discussion: Our studies show that the UC-MSCs secrete pro- and anti-inflammatory interleukins. The concentration of anti-inflammatory interleukins shows to be increasing, while the pro-inflammatory interleukins are decreasing within the longer incubation time, but this not be applicable for IL-10 and IL-6. IL-6 has the highest concentration among other ILs. These results may provide important clues regarding when is the right time for secretome to be used in therapy patients, because all the molecules in the secretome can lead to many clinical manifestations.