The U.S. Patent and Trademark Office on Monday issued Cellular Dynamics International a patent that relates to the method by which adult tissue cells are reprogrammed into induced pluripotent stem (iPS) cells by the insertion of episomal vectors, the company announced.

According to CDI, episomal vectors used in reprogramming are circular pieces of DNA that, when introduced into adult tissue cells, express genes known as reprogramming factors that drive the adult tissue cells back to a stem cell state, before then exiting the cell. This method is used by CDI for the creation of its iCell and MyCell products.

“The episomal reprogramming method has been widely adopted for research into therapeutic applications of iPS cell technology,” Bob Palay, chairman and chief executive officer of CDI, said in a statement. “The issuance of this patent to CDI ensures the continued broad availability of this critical technology.”

Patent No. 8,546,140, called “Methods for the Production of iPS Cells Using Non-Viral Approach,” expires on May 2030.