Fig. 5. Digital photographs of hPSC colonies in culture media and optical microscopy images of the same colonies 7 days after their immersion in either a (A) 12% w/w PEG₅₇-PHPMA₆₅ or a (B) 6% w/w PGMA₅₅-PHPMA₁₃₅ worm gel. Fluorescence microscopy images of hPSC colonies obtained after degelation using and Ki-67 and NES immunolabeling. Colonies immersed in 12% w/w PEG₅₇-PHPMA₆₅ worm gel were Ki-67 (+) and NES (−), whereas colonies immersed in 6% w/w PGMA₅₅-PHPMA₁₃₅ worm gel gave Ki-67 (−) and NES (+). [N.B. In the former hydrogel, the cell culture medium (Nutristem) changes in colour from pink to yellow, indicating its gradual acidification. This is consistent with continuous cell proliferation within this hydrogel].