The Lat­est In­tel­li­gence

The tech­nique rep­re­sents an im­por­tant step to­wards grow­ing hu­man or­gans for trans­plant, say re­searchers

BBC Earth (Asia) - - Contents -

Long-ever black hole feed­ing frenzy recorded, clues to the evo­lu­tion of birds’ beaks found in an­cient di­nosaur fos­sils, could Mar­tian set­tlers live in ice houses

A team at the Salk In­sti­tute has grown the first liv­ing embryos con­tain­ing cells from both hu­man be­ings and pigs.

To cre­ate the hu­man-pig chimeras, the re­searchers in­jected hu­man stem cells – mas­ter cells that can de­velop into any type of tis­sue – into pig embryos. The stem cells sur­vived and be­gan to in­te­grate with the pig tis­sue to form a chimeric hu­man-pig em­bryo. These embryos were im­planted in sows and al­lowed to de­velop for up to four weeks.

“This is long enough for us to try to un­der­stand how the hu­man and pig cells mix to­gether early on, with­out rais­ing eth­i­cal concerns about ma­ture chimeric an­i­mals,” said lead in­ves­ti­ga­tor Juan Car­los Izpisua Bel­monte.

How­ever, the process is cur­rently very in­ef­fi­cient – out of the 2,075 embryos cre­ated, just 186 stayed alive for the full four weeks.

“It’s like when you try to du­pli­cate a key. The du­pli­cate looks al­most iden­ti­cal, but when you get home, it doesn’t open the door. There is some­thing we are not do­ing right,” said Izpisua Bel­monte. “We thought grow­ing hu­man cells in an an­i­mal would be much more fruit­ful. We still have much to learn about the early de­vel­op­ment of cells.”

Though they sound dis­turb­ing, hu­man-an­i­mal chimeras may some­day pro­vide a means of grow­ing hu­man tis­sues and or­gans for trans­plant – po­ten­tially sav­ing thou­sands of lives.

“The ul­ti­mate goal is to grow func­tional and trans­plantable tis­sue or or­gans, but we are far away from that,” said Izpisua Bel­monte. “This is an im­por­tant first step.”

The next step is to guide the stem cells into form­ing spe­cific hu­man or­gans within the pigs. The team has pre­vi­ously used CRISPR genome edit­ing tools to

delete spe­cific genes in­volved with or­gan de­vel­op­ment in fer­tilised mouse egg cells and re­place them with rat stem cells. As the or­gan­ism ma­tured, the rat cells filled in where mouse cells could not, form­ing the func­tional tis­sues of the or­gan­ism’s heart, eye or pan­creas.

The re­searchers are now work­ing on re­pro­duc­ing this ef­fect in the hu­man-pig embryos.



ABOVE: The work of the Salk In­sti­tute team, led by Juan Car­los Izpisua Bel­monte, could pave the way for lab-grown

trans­plant or­gans

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