Long-term <i>in vitro</i> culture alters MSC morphology independent from the donor age.

<p>(<b>A</b>): Cell diameter of aMSCs and yMSCs decreases during the course of long-term cultivation. Diagram shows the cell size distribution of MSCs measured by CASY® TT cell analyzer system at indicated passages after trypsinization. (<b>B</b>): Cellular area of attached aMSCs and yMSCs significantly decreases during <i>in vitro</i> aging. Measurements were performed from fluorescence images of identical exposure conditions. (<b>C</b>): Representative images of phalloidin labeled MSCs highlight reduction of cellular expansion. Additionally, <i>in vitro</i> aged aMSCs and yMSCs exhibited less filopodia, lamellipodia and cell spreading (white arrows). * indicates statistical significance (p<0.05).