7. Replacement Is a Plausible Antiaging Strategy

Replacing non-neural organs and systems could, in principle, partially rejuvenate the body while preserving continuity of neural function. Replacement becomes a particularly attractive path to radical longevity because it can bypass some biological complexity: instead of repairing every component of the deleteriome, we can exchange the most failure-prone parts for younger, functional ones (75). However, this strategy is inherently brain-limited, which may ultimately constrain the benefits of systemic replacement. Long-term success will require scalable and ethical sources of immunologically matched organs (e.g., iPSC-derived and developmentally matured tissues), better tolerance/rejection solutions, and coordinated multiorgan replacement strategies (from en-bloc swaps all the way to staged, body-wide replacement below-the-neck) that reset physiology rather than treat organ failure sequentially. Tools to replace some cell types with younger ones (e.g., hematopoietic stem cells, T cells, microglia) may be developed relatively soon, but those for organ/tissue replacement may take longer.