Chiropa chemunhu chinoramba chiri chepwere kunyangwe miviri yedu yese ichichembera, maererano netsvagiridzo itsva, uye paavhareji nhengo yacho haisviki makore matatu, zvisinei kuti izera ripi remunhu. Kushandisa masvomhu modelling uye a nzira inonzi retrospective radiocarbon birth dating – iyo inotora masero evanhu zvichienderana nemazinga e carbon isotope iyo yakanyura mumhepo mushure mepakati pezana remakore rechi20 kuongororwa kwenyukireya – masayendisiti akawana kuti kuvandudzwa kwechiropa hakuitike zvakanyanya sezvatinochembera.
Kuvandudzwa ikoko ndiko kwakakosha pakushanda kwechiropa, uko kuri kubvisa zvinhu zvine chepfu mumuviri. Kubviswa kwemarara uku kunotora marara panhengo, asi ine hunyanzvi hwekuzvigadzira patsva mushure mekukuvadzwa.
“Pasinei nokuti une makore 20 kana kuti 84, chiropa chako chinoramba chiri paavhareji ari pasi pemakore matatu chete,” anodaro nyanzvi yemamorekuru Olaf Bergmann wokuDresden University of Technology kuGermany.
Chikwata chakaongorora post-mortem uye biopsy tishu samples kubva kune vanopfuura makumi mashanu vanhu vane makore ari pakati pemakumi maviri ne84 makore. Vakaona kuti biology yedu inoramba iine simba pamusoro pehuwandu hwechiropa muhupenyu hwedu hwese, kuburikidza nekugara vachitsiviwa kwemasero echiropa. Sezvo miviri yedu inokura, haichakwanisi kumutsiridza masero nekugadzirisa. Icho chidzidzo chitsva chinoratidza ndechekuti izvi hazvishande kune hepatocytes, masero ari muchiropa. Nepo zvidzidzo zvekare zvemhuka zvakapa mhedzisiro inopokana, pano pane kujeka kwakawanda.
However, not all liver cells are the same in terms of how quickly they renew: A small fraction can live to be up to 10 years old, the researchers found. This seems to be related to how many sets of chromosomes they’re carrying.Most cells in our body, aside from our sex cells, carry two copies of our entire genome. Liver cells are an odd exception, with a proportion of cells generating even more copies of our whole DNA library on top.
“When we compared typical liver cells with the cells richer in DNA, we found fundamental differences in their renewal,” says Bergmann. “Typical cells renew approximately once a year, while the cells richer in DNA can reside in the liver for up to a decade.”
“As this fraction gradually increases with age, this could be a protective mechanism that safeguards us from accumulating harmful mutations. We need to find out if there are similar mechanisms in chronic liver disease, which in some cases can turn into cancer.”
This is an important new insight into the biological mechanisms underpinning how the liver works – and of course the more we know about the organs in the body, the better we can get at figuring out how to keep them healthy and how to cure them from disease.
The researchers are also looking at other organs, including the heart, to see how fast cells are renewed across the body. The same technique of retrospective radiocarbon birth dating can be used to accurately date cells and work out renewal rates.
It’s one of the best methods we’ve currently got for figuring out the age of human tissue, using the decay rates of radiocarbon in the atmosphere to correspond to traces in the body. As it turns out, your organs might not be as old as you feel.
“Our research shows that studying cell renewal directly in humans is technically very challenging but it can provide unparalleled insights into the underlying cellular and molecular mechanisms of human organ regeneration,” says Bergmann.
Ongororo yabudiswa neCell Systems.