This bugs me more and more with every issue. Regardless of what effects the Super Soldier serum have, being frozen is what kept him young for all those years. The whole reason Bucky (who is super soldier serum-free) is still so young is that the Russians would put freeze him after each mission so that he had very little time out in the world in which to age. Cap was frozen at around 25, its seems to have been about 10 years in comic time since he was thawed and he spent another 10 in Dimension Z so he should be mid-40s tops....
Actually, Steve should have died from the ice. Hypothermia. I forget where I read it, but it was posited some time ago that the SSS is what kept him alive while he was on ice and deprived of oxygen. Suspended animation sounds nice in comics, but I can assure you that if your brain, cells, skin tissue, etc., don't get enough oxygen or even vitamin D from the sun, there will be adverse effects on the human body. Even a peak human body. The SSS was more or less the panacea for all of those potential ailments.
As for an explanation from a medical standpoint, there have been theories proposed that the brain and many of the body's cells have a prescribed shelf life that is encoded into our very DNA. At some point the body will automatically start to break down once that process is triggered. My hunch is that the SSS was the only thing forestalling that process by blocking the synapse between the brain/cell lifecycle timer and the ageing trigger. If so, then it's easy to see why Steve is getting old so rapidly. If his cells had their own internal life cycle timer, then the period that he was in suspended animation would still be taken into account by that internal clock. The time that he spent in another universe would also be taken into account. Stripping Steve of the SSS, however, would remove the one impediment between the life cycle clock and the deterioration trigger...and by this point, I'm betting the life cycle timer would be screaming in full throat to start the cellular deterioration. About as loudly as the Tunguska meteor exploding in your ear canal.
The reason why humans aren't immortal isn't because our organs and cells don't want to continue on, it's because our bodies dictate that our time is finite.
Last edited by JudicatorPrime; 09-04-2014 at 09:39 PM.