There are suggestions that mesenchymal stem cells, epigenetic reprogramming, gene therapy for telomere lengthening, organ replacement and drugs may all have the ability to, in some specific tissues, trigger reversion to an earlier state. Stem cells can even be reset to age zero — this process has been used to regenerate a crushed optic nerve.17 A gene therapy has been mooted to reverse the processes of multiple age-related diseases.18 Gene editing has corrected a progeria mutation in mice allowing them to double their lifespan19.
This remains a difficult research programme with many barriers to overcome. Most of the treatment approaches are currently very expensive, and there is no animal model organism or trial that could tell us how far these increase the human lifespan — waiting for results would take a prohibitive amount of time. However, it should not take long to discover whether these therapies have real effects on healthspan and as ageing biomarkers become more validated, it may be possible to estimate their effects on lifespan.