To Explore The Effect Of Human Umbilical Cord Mesenchymal Stem Cells Secreted Exosomes On K562 Cell Growth

Objective:(1) to study how the exosomes secteted by umbilical cord mesenchymal stem cells effect on K562 cell proliferation and apoptosis in vitro.(2) to study the effect of exosomes secteted by umbilical cord mesenchymal stem cells on classic Wnt/beta-catenin signaling pathways activated in K562 cell lines.Methods:(1) hUC-MSCs were isolated and purified from human umbilical cord by adherent method,then cultured in the culture medium in vitro.(2) Culture supernatant of h UC-MSCs(P3-P6)were collected by differential ultracentrifugation to separate and concentrate exosomes. Transmission electron microscopy(TEM) and flow cytometry were used to identify the quality of isolated exosomes. The amount of exosomes was quantified through bicinchonic acid protein assay.(3) Cultivate K562 cells in virto, treated with different concentrations of esosomes secteted by umbilical cord mesenchymal stem cells. After co-cultured for 72 h, proliferation and apoptosis were determined by MTT and flow cytometry technology with Annexin V- FITC/PI double dyed.(4) After co-cultured for 72 h in vitro, Rt-pcr method were used to detect beta-catenin m RNA expression, Western blot test were used to detect beta-catenin protein expression in the experimental group and control group in K562 cells.Results:(1)Human umbilical cord derived mesenchymal stem cells were isolated from the umbilical cord of the newborn to meet the international standard.(2) exosomes derived from umbilical cord mesenchymal stem cells were isolated by differential ultracentrifugation. Exosomes look like a disk from TEM.(3)MTT results showed that human umbilical cord mesenchymal stem cells derived exosomes have inhibitory effect on the proliferation of K562 cells; Flow cytometry results showed that the experimental group K562 apoptosis rate was(12.03±1.2) %, compared with control group results(1.207±0.09)%, the difference is statistically significant.(4) The RT-PCR results from the study showed that the relative expression of β-catenin m RNA was(18.33±0.6566) %,compared with thecontrol group(24.33±0.4910) % significantly decreased. Western blot results from the study showed that β-catenin protein expression of the relative amount(34.23±1.841) % compared with the control group(64.00±2.676) % significantly decreased.Conclusion:Human umbilical cord mesenchymal stem cells derived exosomes inhibit the proliferation of K562 cells, and promote its apoptosis. Human umbilical cord mesenchymal stem cells secreted exosomes can inhibit the activity of K562 cells Wnt/β-catenin classic way.