In order for a PI leaving your institution to take materials obtained from Addgene with them to a new institution, the PI will need to get a new MTA. Many people have found that the easiest way to obtain this MTA is to order the materials under their new institution through Addgene. This way, a new MTA can be issued which contains the name/information of the PI at their new institution where the materials will be used. Addgene may be able to provide a discount for re-ordered items. Please contact firstname.lastname@example.org for more information.
Alternatively, you may contact each of the institutions that originally deposited the materials and ask them for permission to use the materials at your new institution. Addgene is not authorized by those institutions to grant such permissions.
If the MTA is the UBMTA, it can be terminated if the original recipient PI leaves the original recipient institution and does not wish to take Addgene materials with them (or if the new institution does not wish to approve the new MTA). Email email@example.com for more information.