How do induced pluripotent stem cells originate from adult skin cells?

Induced pluripotent stem cells (iPS cells) are generated by "reprogramming" mature adult somatic cells, such as skin cells, back into a primitive, pluripotent state. This process allows these cells to regain the capacity to differentiate into any cell type in the body, offering a less controversial alternative to using embryonic stem cells.12

The transformation is achieved by introducing specific regulatory genes into the nuclei of adult cells. The general procedure involves:1

• Gene Delivery: Scientists insert combinations of regulatory genes—which encode transcription factors such as Oct-4, Sox-2, Klf-4, and Nanog—into viral vectors, most commonly retroviruses.132
• Reprogramming: These vectors transport the genes into the adult cells grown in cell culture. Once inside, the genes are incorporated into the cell's DNA, where they trigger the regulation of other genes to confer embryonic stem cell-like properties.12
• Alternative Methods: Because retroviruses can integrate into the genome and potentially cause tumors, researchers are exploring safer alternatives, such as plasmids or the direct delivery of proteins and modified RNAs.12

Once reprogrammed, these iPS cells can be used to model genetic diseases or serve as autogeneic sources for regenerative medicine, significantly reducing the risk of immune rejection.132