That should be RNA not DNA (they pack the virus with RNA that...

That should be RNA not DNA (they pack the virus with RNA that codes for the CAR - virus transfects the T cell or MSC cell - RNA is converted to DNA in the cytoplasm (reverse transcriptase) then the DNA gets transported into the nucleus where it's integrated into existing DNA then the CARs are produced and moved to and fitted into the membrane.

For anyone interested in the CAR engineering process & T cell action (transfection basics apply to T + MSC CAR production) the animation in this video for CAR-T from Peter McCallum here in Melbourne is v.cool (Biomedical Animator Dr Maja Divjak).

LINK: https://youtu.be/CxxuqIDyF_I?si=qzojYUWgOkPjMkB9

Also Dr. Maja! https://youtu.be/DcrcKw-afV0?si=KRbbRq60wMn3-98l

Also saw somewhere that one of the first beneficiaries of early CAR-T Cell therapy who was completely cured back in 2010 still had effective CAR modified T cells patrolling his system 10 years later - MSCs don't behave this way, they're dead within 10 days and cell death (apoptosis) is an integral part of their immunomodulatory process.