Effect of Serial Passage on Growth Kinetics, Biological Properties, and Differentiation into Adipocytes of Human Wharton's Jelly-Derived Mesenchymal Stem Cells

Early passges of human Wharton's jelly-derived mesenchymal stem cells (hWJMSCs) have been suggested by various studies; however, the effect of serial passaging has not been well defined. This study aimed to investigate the effect of serial passage on the growth kinetics, biological properties and differentiation into adipocytes on hWJMSCs. This study was conducted from April to December 2014 to evaluate the hWJMSCs growth kinetics at passage 6 (P6) and P12 by calculating proliferation rate, population doubling time (PDT), and cumulative population-doubling levels (CPDL) using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium MTS assay kit. The cells biological properties were characterized using flow cytometry analysis followed by measuring the differentiation into adipocytes in extensive culture using Oil Red O staining after induction. An independent sample t-test was applied to analyze the differences between groups using IBM SPSS Statistics Version 22 with a p<0.05 considered significant. The growth kinetics assay showed the cells at P6 had a higher proliferation rate, CPDL, and faster PDT compared to the cells at P12 (p<0.05). Data from expression of MSCs surface markers showed that the cells retained their biological properties at both passages but decreased at P12 (p<0.05). The formation of intracellular lipid droplets was also observed at both passages under adipogenic induction. However, the content of oil red O extracted-cells decreased at P12 (p<0.05). The hWJMSCs decreased their growth kinetics, biological properties, and differentiation into adipocytes as a result of serial passage. This finding might be valuable for treating degenerative diseases using cell-based therapy.