Not so for the HEART and BRAIN.

Aubrey de Grey & Michael Rae (Ending Aging: The Rejuvenation Breakthroughs That Could Reverse Human Aging in Our Lifetime, 2007) wrote …

“[Ulf] Brunk had done some first-class work in assessing the role of lipofuscin in cultured heart cells — an important technical advance, especially because, in the body, heart cells never divide. When a cell divides, its load of cellular junk — including lipofuscin — is shared between the two daughter cells. Each now has half as much, on average, and this will continue with each new generation. If the junk is only being generated quite slowly, this dilution process will fully balance the rate of creation of new junk and an unmanageable level of junk will never accumulate. The quickly replicating skin cells that had been used in much previous work did just this — they tended to dilute out lipofuscin and other cellular junk, and so could not replicate the real effects of lysosomal buildup in critical nondividing cells like those of the heart and brain.”

In other words, the skin is the snowflake on the tip of the iceberg.