Today researchers are able to reprogram cells that are obtained from adult tissues to turn back in development into cells that resemble embryonic stem cells. These cells are called induced pluripotent stem cells, or iPS cells.
Cells that are reprogrammed into stem cells from specialized cells are called induced pluripotent stem cells, iPS cells. Reprogramming of for example skin cells or blood cells into iPS cells involves artificial activation of the genes that control pluripotency. By introducing the needed gene regulators into the cells (into for example fibroblasts) in the laboratory, the cells change into iPS cells through a multifaceted process.
In the year 2006, it was shown that expression of just four gene regulatory proteins (the so-called Yamanaka factors) in specialized mouse cells was sufficient to reprogram the cells into iPS cells. Already a year later, iPS cells were made also from human cells. Since then, the iPS techniques have developed substantially and in 2018 a Finnish research group showed for the first time that skin cells can be transformed into iPS cells by activating only the reprogramming factors that are found naturally in the cells’ DNA.
Similar to embryonic stem cells, iPS cells can also be differentiated in the laboratory into cells that closely resemble the specialized cells of tissues. In contrast to embryonic stem cells, iPS cells can theoretically be made from any individual quite easily. Patient-derived iPS cells have therefore become an important tool for research of many diseases.
It is not usually possible to isolate and expand sufficient amounts of specialized tissue cells from patients. Reprogramming of patient skin cells into iPS cells and further differentiation of them into specialized cells that are relevant for studying the disease in question, for example into nerve cells, allows the researchers to study the disease mechanisms more in detail. By utilizing bio banks, which contain cells from carefully selected patients, it’s possible to study how risk genes influence the disease and even test different drug treatments on cells before clinical trials.