"Long before it's in the papers"
June 04, 2013


Your brain cells may be capable of outliving you—by a lot

Feb. 25, 2013
Courtesy of PNAS
and World Science staff

Some brain cells of mam­mals can long out­live the an­i­mal to which they orig­i­nally be­longed, if trans­planted in­to a dif­fer­ent brain, new re­search sug­gests.

The find­ings are raising scientists’ hopes that if they find a way to greatly in­crease hu­man life­span, brain cells will co­op­erate by work­ing long­er accord­ing­ly.

In mam­mals, neu­rons, the main type of in­forma­t­ion-processing brain cells, can last a whole life­span in the ab­sence of brain dis­ease. But it has been un­clear wheth­er neu­rons have a max­i­mum life­span, si­m­i­lar to oth­er types of cells in the body which, un­like neu­rons, nor­mally can rep­li­cate.

To find out, Lo­ren­zo Ma­grassi of the Uni­vers­ity of Pa­via in Italy and col­leagues trans­planted pre­cur­sor neu­rons from the de­vel­op­ing mouse in­to rat em­bryos. They used a strain of rat that can live on av­er­age nearly twice as long as the do­nor mouse strain. The cells came from, and were trans­planted to, a part of the brain known as the cer­e­bel­lum.

The trans­planted cells de­vel­oped in­to nor­mal neu­rons that made them­selves at home in the rat brains, though they re­tained a mouse-like size and shape, the re­search­ers said. More­o­ver, these cells sur­vived for as long as their rat hosts, or up to 36 months, roughly twice as long as the av­er­age life­span of the do­nor mice. 

The find­ings sug­gest that the life­span of the trans­planted neu­rons is not ge­net­ic­ally fixed and may have been de­ter­mined by the rat brain “mi­croen­vi­ron­ment,” Ma­grassi and col­leagues wrote. They re­ported their find­ings in this week’s early on­line is­sue of the jour­nal Pro­ceed­ings of the Na­tio­n­al Aca­de­my of Sci­en­ces.

The re­sults, they added, al­so sug­gest that in­creas­ing longe­vity—a hall­mark of tech­no­log­ic­ally ad­vanced so­ci­eties—won’t nec­es­sarily sad­dle longer-lived peo­ple with a prob­lem of many dy­ing brain cells.

“Our re­sults sug­gest that neu­ronal sur­viv­al and ag­ing are co­in­ci­den­t but sep­a­ra­ble pro­cess­es,” they wrote. This in­creases “our hope that ex­tend­ing or­gan­is­mal life­span by di­e­tary, be­hav­ior­al, and phar­ma­co­logic in­ter­ven­tions will not nec­es­sarily re­sult in a neu­ronally de­plet­ed brain.”

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Some brain cells of mammals can long outlive the animal to which they originally belonged, if transplanted into a different brain, new research suggests. In mammals, neurons, the main type of information-processing brain cells, can last a whole lifespan in the absence of neurodegenerative disease. But it has been unclear whether neurons have a maximum lifespan, similar to other types of cells in the body which, unlike neurons, normally can replicate. To find out, Lorenzo Magrassi of the University of Pavia in Italy and colleagues transplanted precursor neurons from the developing mouse into rat embryos. They used a strain of rat that can live on average nearly twice as long as the donor mouse strain. The cells came from and were transplanted to a part of the brain known as the cerebellum. The transplanted cells developed into normal neurons that made themselves at home in the rat brains, though they retained a mouse-like size and shape, the researchers said. Moreover, these cells survived for as long as their rat hosts, or up to 36 months, roughly twice as long as the average lifespan of the donor mice. The findings suggest that the lifespan of the transplanted neurons is not genetically fixed and may have been determined by the rat brain “microenvironment,” Magrassi and colleagues wrote. They reported their findings in this week’s early online issue of the journal pnas. The results, they added, also suggest that increasing longevity—a hallmark of technologically advanced societies—won’t necessarily saddle longer-lived people with a problem of many dying brain cells. “Our results suggest that neuronal survival and aging are coincidental but separable processes,” they wrote. This increases “our hope that extending organismal lifespan by dietary, behavioral, and pharmacologic interventions will not necessarily result in a neuronally depleted brain.