Abstract: A method and an apparatus for reprogramming living cells without using viruses. In that method a cocktail comprising at least two transcription factors and a microRNA is transfected into the interior of at least one cell in order to convert this cell into iPS cells or into another type of cell, by storing the cells to be converted in an aqueous environment of the cocktail without viral carriers and focusing a femtosecond laser in a laser scanning microscope with a numerical aperture between 0.9 and 1.5 on a cell membrane of the cell to be reprogrammed and controlling the position of the focus. The exposure period and laser power for the optical treatment of the cell such that the focus depending on the pulse repetition frequency with an output between 7 mW and 100 mW generates a transient small-pore hole with a size up to 500 nm.