2020-02-01_New_Scientist

10 | New Scientist | 1 February 2020

THE race to create pigs with organs

that are suitable for transplanting

into people is hotting up. At least

three teams have added human

genes to pigs to try to prevent

donor organs from being rejected

by a recipient’s immune system.

The research could solve two

problems. The first is a shortage of

human donor organs. The second

is that people who get transplants

need to take medicines for the rest

of their lives to suppress their

immune system and avoid the

new organ being rejected.

Different research teams are

trying to tackle this by adding

human genes to pigs, in an effort

to make their organs suitable for

humans, and potentially less likely

to be rejected by the recipient’s

immune system too.

Lijin Zou at the First Affiliated

Hospital of Nanchang University

in China and his colleagues have

created pigs into which they added

eight human genes that reduce

the chance of a donor organ being

rejected, and removed three key

pig genes that trigger organ

rejection. The group then

transplanted skin from these

pigs to monkeys. The skin graft

survived for up to 25 days without

the monkeys needing any

immune system suppressing

drugs (bioRxiv, doi.org/dkkn).

“So far, it is the best result, at

least from the English literature,”

says Zou. His team is preparing to

start human trials of the pig skin

as a temporary cover for extensive

burns. These are usually covered

with skin from dead human

donors while new skin grows.

Zou says he would “expect even

better” results in humans.

Interest in this kind of approach

has surged in the past decade as

advances such as CRISPR gene

editing have made it feasible

to make extensive changes

to the genomes of animals.

In December, Luhan Yang at

biotech firms Qihan Bio in China

and eGenesis in the US reported

that her team had created pigs

with nine added human genes

and dozens of deleted pig genes.

In addition to deleting the same

three genes knocked out by Zou’s

team, Yang’s team also inactivated

dozens of pig viral genes known as

porcine endogenous retroviruses,

or PERVs (bioRxiv, doi.org/ggf4s2).

“It is a major technological

achievement,” says David Cooper

of the University of Alabama

at Birmingham, a former

transplant surgeon who works

on transplanting pig organs.

But regulators will want to know

whether all of these genetic

changes are necessary, he says.

Cooper is working with US

biotech company Revivicor, which

has added six human genes to

pigs, as well as deleting the same

three pig genes as the other teams.

“I believe that any of these pigs

will be suitable for a clinical trial

[in humans], but we have to

persuade the regulatory

authorities first,” he says.

If PERVs start infecting human

cells after a transplant, there is a

risk they might cause cancer years

later, says John Coffin at Tufts

University School of Medicine

in Boston. But this is still better

than the outcomes if people

don’t get a transplant, he says. ❚

“Body modifications are

often associated with social

maturation, like puberty

and rites of passage”

Organ transplants

Michael Le Page

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News

Ancient humans

People have been

getting piercings

for a ver y long time

A YOUNG man who lived over

12,000 years ago in east Africa

probably had facial piercings. The

finding suggests people have been

wearing facial piercings in Africa

since deep in prehistory.

“We’re potentially opening

a window into the life of this

individual,” says John Willman

at the University of Coimbra in

Portugal. Body modifications

“are often associated with social

maturation, things like puberty and

rites of passage”, he says.

He has been studying the skull

of a young adult male known as

Olduvai Hominid 1, or OH1. It was

discovered in 1913 in Olduvai

gorge in Tanzania. In 1993,

researchers noted unusual wear

on OH1’s teeth. They thought this

was due to chewing tough plants.

“I took one look at it and said ‘no’,”

says Willman, who has studied the

jaws of First Peoples in Canada

who had facial piercings. So he and

his colleagues re-examined and

measured OH1’s teeth and jawbone.

They found that the incisor teeth

were worn at the front. “It looks

almost like somebody took the

front end off these teeth with an

ice cream scoop,” he says.

Towards the back of the mouth,

the premolars and molars were also

worn. “All the curvature you can feel

when you run your tongue over your

cheek teeth is virtually gone,” says

Willman. The team believes these

wear patterns mean OH1 had three

facial piercings: a “labret” through

his lower lip, and one in each cheek

(American Journal of Physical

Anthropology, doi.org/dkhm).

Because the piercings haven’t been

preserved, we don’t know what

they were made of or looked like.

OH1 lived between 12,000 and

20,000 years ago, making him the

oldest known example of facial

piercings in Africa and the second

oldest in the world. Previously, most

evidence for piercings came from

humans who were alive in the last

5000 years. The oldest instance

of cheek piercings on record is in

central Europe 25,000 years ago. ❚

Michael Marshall

Human genes given to pigs to create

rejection-proof skin for transplants

Genetically engineered

pigs could provide organs

suitable for transplant