Fig. 2

a Representative toluidine blue stain for total proteoglycans demonstrates smaller pellets with less metachromasia for low-GAG MSC preparations and ACP clones in both hyperoxia and physioxia relative to paired high-GAG MSC preparations and ACP clones at the respective oxygen levels. Images were acquired with bright-field microscopy, scale bars = 100 μm. b Measurement of pellet diameter revealed a statistically significant difference in pellet size between both MSCs and ACPs of high or low chondrogenicity and between high-GAG MSCs at physioxia or hyperoxia. Statistical significance defined as *p < 0.05, **p < 0.01, ****p < 0.0001. ACP articular cartilage progenitor, GAG glycosaminoglycan, MSC mesenchymal stem cell