Are all cells of the human body completely replaced every seven to ten years?

Question

It have heard several times that, every seven to ten years, all the cells that our body are made of have all been replaced. Example in this NY Times Article

This heartening truth, which arises from the fact that most of the body's tissues are under constant renewal, has been underlined by a novel method of estimating the age of human cells. Its inventor, Jonas Frisen, believes the average age of all the cells in an adult's body may turn out to be as young as 7 to 10 years.

Is this claim accurate?

Answer 1

Different types of cells have different lifespans, e.g.:

• we shed our skin cells about every 35 days

• red blood cells live about 120 days, platelets 6 days and white cells less than a day

• most of the adult skeleton is replaced about every 10 years

• the average age of a fat cell seems to be about 10 years

• a 25-year-old heart replaces about 1% of all its cardiomyocytes (heart muscle cells ) over the course of a year, while a 75-year-old heart replaces about half a percent

• our neocortical neurons, the cell type that mediates much of our cognition, are produced prenatally and retained for our entire lifespan

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I want to throw in a philosophical side note and quote computer scientist Steve Grand:

"Think of an experience from your childhood. Something you remember clearly, something you can see, feel, maybe even smell, as if you were really there. After all, you really were there at the time, weren’t you? How else would you remember it?

But here is the bombshell: you weren’t there.

Not a single atom that is in your body today was there when that event took place … Matter flows from place to place and momentarily comes together to be you.

Whatever you are, therefore, you are not the stuff of which you are made.

If that doesn’t make the hair stand up on the back of your neck, read it again until it does, because it is important."

[Richard Dawkins uses this quote in his TED Talk (around 10:20)]

More:

• Times Higher Education: most cells are younger than the individual
• ABC Science: Regrowth mystery reborn

Answer 2

No, it isn't true that all the cells in our body are replaced every 3/7/10 years.

Some cells are never replaced.

In this article about the eye:

R.G.A. Faragher, B. Mulholland, S.J. Tuft, S. Sandeman, P.T. Khaw, Brief review on aspects of aging and the eye: Aging and the cornea Br J Ophthalmol 1997;81:814-817 doi:10.1136/bjo.81.10.814

they explain:

Non-dividing cells are those from static cell populations (exemplified by cerebral neurons) which never divide during adult life.

To support this, they cite an earlier article (which I haven't read):

Leblond CP(1964) Classification of cell populations on the basis of their proliferative behaviour. Natl Cancer Inst Monogr 14:119–149.