Clean-Up Human Embryonic Stem Cell Lines Using Humanized Culture Condition

Human embryonic stem cell (hESC) culture system has been changing culture conditions from conventional to xeno-free for therapeutic cell applications, and N-glycolylneuraminic acid (Neu5Gc) could be a useful indicator of xenogeneic contaminations in hESCs because human cells can no longer produce it genetically. We set up the humanized culture condition using commercially available humanized materials and two different adaptation methods: sequential or direct. SNUhES4 and H1 hESC lines, previously established in conventional culture conditions, were maintained using the humanized culture condition and were examined for the presence of Neu5Gc. The hESCs showed the same morphology and character as those of the conventional culture condition. Moreover, they were negative for Neu5Gc within two passages without loss of pluripotency. This study suggested that this method can effectively cleanse previously established hESC lines, bringing them one step closer to being clinical-grade hESCs.

Quantitative determination of sialic acid in Indian milk and milk products.

Background: Sialic acids are acidic sugars with a 9-carbon backbone, expressed as terminal residue on mammalian glycoconjugates. Sialic acid was found in two forms as N-acetylneuraminic acid (Neu5Ac) and N-Glycolylneuraminic acid (Neu5Gc) in meat and milk products. Neu5Ac is important for the brain and neuro development while Neu5Gc is suspected as human carcinogen. There is no data reported on sialic acid content in Indian milk and milk based products. Objective: To determine sialic acid (Neu5Ac and Neu5Gc) content in Indian milk and milk products and thermal stability of non-human sialic acid (Neu5Gc) evaluation. Design: Milk products like chocolate, infant food products, milk based energy drinks, butter etc were examined for the sialic acid content. For Neu5Gc thermal stability studies cow, buffalo, cross cows and processed milk were used. Conclusion: The study indicates the level of sialic acid (Neu5Ac and Neu5Gc) in Indian milk and milk based products. Further the stability studies shows degradation (20 to 22 %) of non-human sialic acid (Neu5Gc) to the total sialic acid content.