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Cells have memory just like humans, according to research by Harvard Medical School scientists, who have isolated genes in order to erase a cell's memory when it is suppressed. This makes the cell more susceptible to reprogramming and the process very efficient, enabling the creation of stem cells that can evolve into any cell type.

"We began this work because we wanted to know why a skin cell is a skin cell, and why does it not change its identity the next day, or the next month, or a year later?" said Konrad Hochedlinger, co-senior author of the study.

Scientists observed that every cell in the human body has the same DNA blueprint, and the "on-off" switch during development determines what each will become later in life. With such new information, these genes can be manipulated more easily and dormant parts of an adult cell's genome can be unlocked and reprogramed into another cell type.

The chromatic regulator CAF-1 played a big role in retaining cellular memory. By limiting the factor, reprogramming, or erasing a cell's memory, it gets easier to create stem cells.

"The CAF-1 complex ensures that during DNA replication and cell division, daughter cells keep their memory, which is encoded on the histones that the DNA is wrapped around," said Ulrich Elling, co-first author of the study. "When we block CAF-1, daughter cells fail to wrap their DNA the same way, lose this information and covert into blank sheets of paper. In this state, they respond more sensitively to signals from the outside, meaning we can manipulate them much more easily."

As CAF-1 can enable cell memory to get erased and rewritten, it gives scientists the ease to change the development of cells into various types.

"The cells forget who they are, making it easier to trick them into becoming another type of cell," said Sihem Cheloufi, second co-first author of the study.

The findings were published in the Dec. 9 issue of Nature.