Cell reprogramming: better less, yes better
Cells created at the Hebrew University in Jerusalem,
withstand the toughest pluripotency test
LifeSciencesToday based on the materials of Hebrew University of Jerusalem:
Hebrew University scientists create therapy-quality stem cells using new cocktail to reprogram adult cellsScientists at the Hebrew University in Jerusalem have developed a new cocktail for reprogramming somatic cells into high-quality induced pluripotent stem cells (iPSCs).
Regenerative medicine is a new rapidly developing field, the method of which is the replacement of lost or damaged cells, tissues or organs by cell transplantation. Since the use of human embryonic stem cells raises ethical questions, a good solution is to reprogram somatic cells into a state close to embryonic, using a combination of reprogramming factors.
The so-called induced pluripotent stem cells resulting from such reprogramming can be used to replace cells lost as a result of injury or disease. However, as scientists have established, the process of reprogramming somatic cells leads to the emergence of genetic anomalies that limit their use both in scientific research and in medicine.
To obtain iPSCs, scientists expose somatic cells to a cocktail of genes active in embryonic cells. iPSCs can then be directed along the differentiation pathway to other cell types, such as neurons or muscle cells. However, the standard combination of factors used for reprogramming leads to serious genomic aberrations. The standard reprogramming factors today are Oct4, Sox2, Klf4 and Myc, collectively known as OSKM.
Scientists from the Hebrew University in Jerusalem have developed a new cocktail of reprogramming factors that allows you to obtain high-quality iPSCs. In this study, Dr. Yosef Buganim from the Israel-Canada Medical Research Institute (Institute for Medical Research Israel-Canada) of the Hebrew University of Jerusalem Faculty of Medicine collaborated with scientists from the laboratory of the founding member of the Whitehead Institute for Biomedical Research Rudolf Jaenisch, professors of the Massachusetts Institute of Technology (Massachusetts Institute of Technology).
Induced pluripotent stem cells (iPSCs) are usually obtained by transduction into Oct4, Sox2, Klf4 and Myc (OSKM) cells. Although iPSCs are pluripotent, they often exhibit a high degree of variability in terms of quality. Reliable, high-quality iPSCs are needed for future therapeutic use. Scientists have shown that the main determinant of iPSCs quality is the combination of reprogramming factors used. Based on tetraploid complementation, they found that ectopic expression of Sall4, Nanog, Esrrb and Lin28 (SNEL) in mouse embryonic fibroblasts generates high-quality iPSCs more efficiently than other combinations of factors, including OSKM. (Fig. Cell Stem Cell)The scientists decided that changing the reprogramming factors would make the process of reprogramming somatic cells more controllable and allow obtaining iPSCs of higher quality.
Working with mouse cells, Dr. Buganim and researcher Styliani Markoulaki used bioinformatic analysis. The result of their work was the creation of a new cocktail of reprogramming factors – Sall4, Nanog, Esrrb and Lin28 – collectively known as SNEL.
The results obtained by the researchers showed that the interaction between reprogramming factors plays an important role in determining the quantity and quality of the iPSCs obtained at the output and that another combination of factors makes it possible to obtain a product of significantly higher quality.
The SNEL cocktail produces quantitatively smaller iPSCs colonies, but about 80% of them pass the toughest pluripotency test. This is a significantly higher result compared to the traditional OSKM cocktail, which gives a large number of colonies, most of which, however, do not stand this test.
Dr. Buganim suggests that SNEL reprograms cells better than OSKM, since it is not based on the main regulators Oct4 and Sox2, which can activate part of the genome of somatic cells. In his opinion, this work demonstrates the effectiveness of bioinformatics tools in obtaining high-quality iPSCs.
This study brings regenerative medicine closer to a clinic where it can help patients in need of transplant therapy. In the near future, Dr. Buganim and his colleagues will strive to find optimal combinations for obtaining human iPSCs. Compared to mouse cells, human somatic cells are generally more difficult to reprogram and cannot be obtained using the SNEL cocktail.
Article by Buganim et al. The Developmental Potential of iPSCs Is Greatly Influenced by Reprogramming Factor Selection published in the journal Cell Stem Cell.
Portal "Eternal youth" http://vechnayamolodost.ru23.09.2014