I recall a few other life-extending treatments.
In the Company War/Alliance–Union universe, Cherryh postulates some sort of rejuv, which leaves the recipient in the prime of life but with grey hair, IIRC. It aids in those long jump-assisted transits, and even more before jump was invented . . .
From Wikipedia: Rejuv, a life-extension drug derived from lifeforms on the planet Cyteen sometime in the 2220s. Rejuv leaves users with the mental and physical capacities they had at the time they started using it (usually in a person's 40s) while extending life up to about age 140; when rejuv failure sets in, life functions collapse rapidly in a one- to two-year period. However, once a person begins using rejuv, they must continue to take it regularly or suffer fatal consequences. Side effects include sterility, some bone and muscle mass loss, and whitening of hair. The Earth Company's inability to control the underground rejuv trade with Union is one of the precipitating factors of the Company War.
Then there was another story, but I forget the details (Niven??). There were teleport booth technology, but one inventor tweaked the tech on a special booth to eliminate physical errors in the 'ported body. It returned the person to the start booth, and the main character used it unknowing, and simply assumed there was a malfunction--until some time later when he noticed his gray hair was growing in dark again or some such effect.
