It just occurred to me that rather than receive blood transfusions of youthful blood, it is more likely the elderly will seek bone marrow transplants. To achieve quality results with least risk they would likely just clone themselves and use their clone's marrow (and possibly stem cells too). There would be entire clone-races, enslaved and maintained in stasis labs, harvested for their organs and tissue. Until one day something would go wrong...perhaps a solar flare of unanticipated magnitude interferes with the clone-lab security systems and the specimens awaken.....