Evaluation of the Capability of the Wharton's Jelly Mesenchymal Stem Cell Aggregates to Express the Markers of Three Germ Cell Lineages

The ability of stem cells to differentiate into different cell types makes them a key component of healing damage in regenerative medicine. As human umbilical cord Wharton's jelly (HUCWJ) is available non-invasively, HUCWJ does not raise any ethical issues with higher differentiation potential compared to adult stem cells. With the ability to express embryonic stem cell markers, HUCWJ can be considered as a good candidate in regenerative medicine applications. The objective of this study was to find if these cells form cell aggregates with the same features as that formed by embryonic stem cells (embryoid body) and could form three germ layers.Eighteen umbilical cords were of healthy infants with parent permission. The umbilical cords were cut into small pieces and the explants were cultured. At the third passage, 1000, 5000 and 10000 cells/ 20 µL were cultured in hanging drops for 3 days. Then, they were incubated for additional 3 days in non-adhesive dishes. As the center of cell aggregates formed from 5000 and 10000 cells were darker than those formed from 1000 cells, this study focused on the aggregates formed by 1000 cells for further assessments. The immunocytochemistry and flowcytometry were performed using 3 color antibodies to detect the markers for three germ cell lineages.The immunohistochemistry data showed that the embryoid-body-like aggregates expressed a low amount of ectodermal and endodermal markers and most of the cells expressed mesodermal markers. The flowcytometry percentage of the cells in each aggregate that expressed ectodermal marker Otx2 was17.1% and endodermal marker, Sox 17 was 5.49%. The frequency of cells expressing mesodermal marker Brachyury was high (75.0%). Flowcytometry also showed the percentages by mathematical evaluation and we did this three times for our result accuracy.These aggregates mainly kept their mesenchymal state and showed a poor differentiation potential toward ectoderm and endoderm identity.