Figure 1.

Bioenergetic (ATP) levels are elevated in mouse embryonic fibroblasts (MEFs) only after prolonged exposure to polylactide (PLA) degradation products (extract). a) Workflow showing our in vitro bioenergetic model. b) Keeping luciferase, oxygen, and d‐luciferin levels constant (red circle) allows for changes in ATP (red arrow) to be measured by luminescence (red arrow). Using in vivo imaging system (IVIS) and in comparison to controls, ATP levels in live cells are increased in blasticidin‐eGFP‐luciferase (BGL)‐transfected MEFs after prolonged exposure to crystalline PLA (cPLA) degradation products. c) Representative microscopic (scale bars, 5 µm) and IVIS images show differential nucleoli number and luminescence, respectively. d) Measuring ATP in cell lysates of wild‐type MEFs revealed that prolonged exposure to both amorphous PLA (aPLA) and cPLA results in elevated ATP levels. e) Addition of PLA does not affect the biochemical reaction by which ATP is measured. f) Between groups on the same day, glucose levels are similar in our in vitro bioenergetic model. Not significant (ns), mean (SD), n = 5 (Figure 1b,d and day 7 for 1e) or n = 3 ((f) and day 12 for (e)), one‐way ANOVA followed by Tukey's post‐hoc test; 100 µl of control or PLA extract was used.