Figure 1.

Single and combined treatment effect of cyclic mechanical stretch (CMS) and hyperoxia (HOX) on lung resident mesenchymal stem cell (MSC) proliferation of preterm infants. CMS and HOX lead to reduced viability and a phenotype change in MSC. A: bright-field microscopy of proliferation after 72 h of selective and combined exposure to CMS and/or hyperoxia (HOX 40% top or HOX 80% bottom). B: change in cell expansion index (CEI). CMS and/or hyperoxic exposure (HOX 40% left and HOX 80% right) led to a dose-dependent inhibition of MSC proliferation. n = 7 different MSC cultures. C: percentage increase of absolute apoptosis induced by selective and combined treatment with CMS and/or HOX (HOX 40% left and HOX 80% right). HOX 40% n = 8 MSC cultures, HOX 80% n = 17 MSC cultures. D: characterization of CD surface markers of resident MSC isolated from tracheal aspirates of preterm infants. Multicolor flow cytometry revealed expression of MSC-characteristic surface markers CD146, CD90 and CD73 whereas the hematopoietic marker CD45 was absent and CD165 weakly positive. Positive fraction of stained cells vs. isotype. Red = unstained control, blue = specific staining. APC, allophycocyanin; BV421, Brilliant Violet 421; FITC, fluorescein isothiocyanate; PE-Cy7, phycoerythrin-cyanine 7.