The liver occupies an interesting intersection between regenerative medicine, the biology of aging, progress towards organ regrowth biotechnologies, and learning how lower animals can naturally regenerate organs. Human livers are more capable of self-repair and regrowth than any of the other internal organs in a human, and also seem to age more gracefully than other aspects of our biology. Researchers who focus on understanding how metabolism leads to aging learn a great deal by examining differences such as these: why one species lives longer or regenerates more readily, or why one organ system degenerates more slowly. So why does the average liver hold its own over the years more effectively than the average kidney or lung? It is possible that the answers to that and other, similar questions may inform the next generation of biotechnologies, capable of slowing or repairing the damage of aging, or capable of granting greater regenerative powers to humans than are presently the case. Equally, they may not - but the research community won't know until they put in the time needed to find out.
On this topic, I recently noticed an open access paper that acts as an introduction to this view of the liver, an organ situated at a crossing point between various fields of study that are relevant to engineered longevity:
Many organ systems exhibit significant age-related deficits, but, based on studies in old rodents and elderly humans, the liver appears to be relatively protected from such changes. A remarkable feature of the liver is its capacity to regenerate its mass following partial hepatectomy.
Reports suggests that aging compromises the liver's regenerative capacity, both in the rate and to the extent the organ's original volume is restored. There has been modest definitive information as to which cellular and molecular mechanisms regulating hepatic regeneration are affected by aging. Changes in hepatic sensitivity to growth factors, for example, epidermal growth factor (EGF), appear to influence regeneration in old animals.
Aging appears to compromise liver regeneration by influencing several pathways, the result of which is a reduction in the rate of regeneration, but not in the capacity to restore the organ to its original volume.
It occurs to me that, given the present state of knowledge and underlying biochemistry, work on liver regeneration - or forms of liver rejuvenation, such as that demonstrated by Cuervo's team three years ago - might be expected to produce significant results ahead of work on other organs, all other things being equal. We shall see.