Methods and compositions for maintaining genomic stability in cultured stem cells
The present application relates to methods and compositions for the generation of therapeutic cells having reduced incidence of karyotypic abnormalities. In several embodiments cardiac stem cells are cultured in an antioxidant-supplemented media that reduces levels of reactive oxygen species, but does not down regulate DNA repair mechanisms. In several embodiments, physiological oxygen concentrations are used during culture in order to increase the proliferation of stem cells, decrease the senescence of the cells, decrease genomic instability, and/or augment the functionality of such cells for cellular therapies.
1. A method for culturing cardiac stem cells for use in the repair or regeneration of cardiac tissue while reducing DNA damage during culturing, the method comprising:
isolating cardiac stem cells, wherein said cardiac stem cells are isolated from healthy mammalian non-embryonic cardiac tissue; and
culturing said isolated cardiac stem cells as a monolayer culture in a culture media comprising an antioxidant composition, said antioxidant composition comprising glutathione present in a concentration ranging from 5 to 20 μM, vitamin C present in a concentration ranging from 0.1 to 20 μM, and vitamin E present in a concentration ranging from 0.1 to 20 μM, wherein said antioxidant composition present in said culture media is sufficient to (i) reduce reactive oxygen species to a level which decreases oxidative stress induced DNA damage, (ii) not reduce markers of DNA repair mechanisms to a statistically significant degree, and (iii) not induce markers of DNA damage in said cardiac stem cells to a statistically significant degree, when compared to cardiac stem cells not contacted with said antioxidant composition.
2. The method according to claim 1 , wherein said glutathione is present in a concentration of 10 μM.
3. The method of claim 1 , wherein said at least one non-peptide antioxidant further comprises one or more of thiols and polyphenols.
4. The method of claim 1 , wherein said at least one non-peptide antioxidant further comprises vitamin A.
5. The method of claim 1 , wherein said at least one of said vitamin C and said vitamin E is present in a concentration of 10 μM.
6. The method of claim 1 , wherein said reactive oxygen species are reduced by at least 10%.
7. The method of claim 1 , wherein said markers of DNA repair mechanisms comprise one or more DNA repair enzymes selected from the group consisting of: ATM, ATR, Rad50, Rad51, Chk1, and Chk2.
8. The method of claim 1 , wherein said markers of DNA damage comprise one or more of γ-H 2 AX foci in cultured cells, γ-H 2 AX mRNA, or γ-H 2 AX protein.
9. The method of claim 1 , wherein said culturing is for at least about 24 hours.
10. The method of claim 1 , wherein said at least one peptide antioxidant is glutathione, wherein said glutathione is present in a concentration ranging from 10 μM, wherein said at least one non-peptide antioxidant comprises vitamin C and vitamin E, and wherein each of said vitamin C and vitamin E is present in a concentration ranging from about 10 μM.