Methods for culturing human embryonic stem cells on feeders

Current methods and challenges in the comprehensive characterization of human pluripotent stem cells

Pluripotent stem cells (PSCs) are powerful tools for basic scientific research and promising agents for drug discovery and regenerative medicine. Technological advances have made it increasingly easy to generate PSCs but the various lines generated may differ in their characteristics based on their origin, derivation, number of passages, and culture conditions. In order to confirm the pluripotency, quality, identity, and safety of pluripotent cell lines as they are derived and maintained, it is critical to perform a panel of characterization assays. Functional pluripotency is determined using tests that rely on the expression of specific markers in the undifferentiated and differentiated states; tests for quality, identity and safety are less specialized. This article provides a comprehensive review of current practices in PSC characterization and explores challenges in the field, from the selection of markers to the development of simple and scalable methods. It also delves into emerging trends like the adoption of alternative assays that could be used to supplement or replace traditional methods, specifically the use of in silico assays for determining pluripotency.

Activin A can induce definitive endoderm differentiation from human parthenogenetic embryonic stem cells

OBJECTIVES

As activin/nodal signaling plays a key role in definitive endoderm (DE) differentiation, we have explored activin A-induced differentiation of DE from human parthenogenetic embryonic stem cells (hPESCs).

RESULTS

Administration of 5 ng activin A/ml had no effect on the expression of markers of DE differentiation. However, higher concentrations of activin A (50 and 100 ng/ml) upregulated Sox17 and Cxcr4, as well upregulating the mesendodermal precursor marker, Brachyury.

CONCLUSIONS

These findings demonstrate that low dose activin A can maintain the undifferentiated potency of hPESCs, whereas higher doses induce DE differentiation; 50 ng/ml is the optimal concentration for inducing DE from hPESCs.

Genetic correction of stem cells in the treatment of inherited diseases and focus on xeroderma pigmentosum

Somatic stem cells ensure tissue renewal along life and healing of injuries. Their safe isolation, genetic manipulation ex vivo and reinfusion in patients suffering from life threatening immune deficiencies (for example, severe combined immunodeficiency (SCID)) have demonstrated the efficacy of ex vivo gene therapy. Similarly, adult epidermal stem cells have the capacity to renew epidermis, the fully differentiated, protective envelope of our body. Stable skin replacement of severely burned patients have proven life saving. Xeroderma pigmentosum (XP) is a devastating disease due to severe defects in the repair of mutagenic DNA lesions introduced upon exposure to solar radiations. Most patients die from the consequences of budding hundreds of skin cancers in the absence of photoprotection. We have developed a safe procedure of genetic correction of epidermal stem cells isolated from XP patients. Preclinical and safety assessments indicate successful correction of XP epidermal stem cells in the long term and their capacity to regenerate a normal skin with full capacities of DNA repair.