Molecular Mechanism Underlying The Difference In Proliferation Between Placenta-derived And Umbilical Cord-derived Mesenchymal Stem Cells

BackgroundMesenchymal stem cells(MSCs),as seed cells with great application prospects in the field of regenerative medicine,have been increasingly used in clinical practice in recent years.MSCs can be obtained from a variety of tissues,among which bone marrow-derived mesenchymal stem cells(BM-MSCs)are particularly widely used.However,the content of MSCs in bone marrow tissue is extremely low,and the content will gradually decrease with age,and even the ability of cell proliferation and differentiation will decrease.Therefore,there are certain limitations in its application.Placenta and umbilical cord are important candidate sources of MSCs besides bone marrow.These two types of MSCs have many advantages over BM-MSCs.Because the placenta and umbilical cord are extremely close in human anatomy,many basic features and functions of the two types of MSCs are extremely similar.However,our study found that placenta-derived mesenchymal stem cells(P-MSCs)have a greater proliferation capacity than umbilical cord-derived mesenchymal stem cells(UC-MSCs).The proliferation ability of MSCs will significantly affect its industrialization and wide application in clinical cell transplantation therapy.Therefore,we further explored the driving factors of this proliferation difference,aiming to reveal the molecular mechanism and signal transduction process of proliferation regulation,with a view toproviding new strategies for the subsequent development of products to promote cell proliferation.MethodsThe basic characteristics of surface markers,differentiation ability and proliferation ability of P-MSCs and UC-MSCs from the same individual were compared.Proteomic profiling and Gene Ontology(GO)functional enrichment were conducted to identify candidate proteins that may influence proliferation.Using lentiviral or small interfering RNA infection,we established overexpression and knockdown models and observed changes in cell proliferation to examine whether a relationship exists between the candidate proteins and proliferation capacity.At the the levels of gene,protein,and cell,real-time quantitative polymerase chain reaction(q RT-PCR),western blot(WB),immunofluorescence analysis(IF),and co-immunoprecipitation(Co-ip)are used to elucidate the mechanisms underlying proliferation.ResultsUnder normal culture conditions,h P-MSCs and h UC-MSCs have similar growth morphology,surface markers,and osteogenic and adipogenic differentiation capabilities,but there are significant differences in their proliferation capabilities.Six candidate proteins were selected based on the results of proteomic profiling and GO functional enrichment.Through further validation in knockdown models,Yes-associated protein 1(YAP1)and β-catenin were confirmed to affect MSCs proliferation rates.The expression level of YAP1 is positively correlated with the expression levels of various cell cycle regulatory genes.YAP1 and β-catenin showed increased nuclear co-localization during cell expansion.YAP1 overexpression significantly enhanced proliferation capacity and upregulated the expression of both β-catenin and the transcriptional targets of Wnt signaling,CCND1 and c-MYC,whereas silencingβ-catenin attenuated this influence.We found that YAP1 directly interacts with β-catenin in the nucleus to form a transcriptional YAP/β-catenin/TCF4 complex.ConclusionOur study revealed that YAP1 and β-catenin caused the different proliferation capacities of P-MSCs and UC-MSCs.Mechanism analysis showed that YAP1 stabilized the nuclear β-catenin protein,and also triggered the Wnt/β-catenin pathway,promoting proliferation.This discovery will help to provide new strategies for the subsequent development of cell proliferation-promoting products and to promote the rapid mass production of MSCs preparations.It will be of great significance for the application of MSCs in cell transplant replacement therapy and regenerative medicine.