Scientific American - November 2018

ADVANCES

12 Scientific American, November 2018

FROM

“BIOINSPIRED POLYMERIC WOODS,” BY ZHI-LONG YU ET AL., IN

SCIENCE ADVANCES,

VOL. 4, NO. 8; AUGUST 10, 2018

producing greater amounts of dystrophin;
levels in skeletal muscle ranged up to
90 percent of normal, depending on the
muscle type and dosage used. (Some dogs
Çß ̧løxl䞐³ž‰D³î§ā§xääÍʳDßlžD­øä-
cle, a crucial target for treatment, levels
climbed to as high as 92 percent of normal.
The U.T. Southwestern researchers, who
ÇøU§žäšxlîšxžß‰³lž³äž³øøäîž³Science,
report that they did not detect any unin-
tended changes to other regions of the
genome—a common concern with gene-
editing technology—and there was no evi-
dence the technique made the dogs ill.
To deliver this technology to the dogs’
muscles, senior author Eric Olson, a
molecular biologist at U.T. Southwestern,
and his colleagues engineered viruses to
act as delivery trucks, stripping out some
̧…îšxþžßøäxäÜ ̧ÿ³%î ̧­D¦xß ̧ ̧­… ̧ß
x³xxlžîž³­Dšž³xßāÍ³ø­Uxß ̧…îšx viruses were then loaded up with the Cas enzyme, which acts like molecular “scis- ä ̧ßäÚçäÿDäøäxlî ̧øî ̧øîîšx%
sequence that hinders dystrophin produc-
tion in muscle cells. Other viruses carried
a guide molecule to help the Cas9 identify
where it should make the needed cuts.
Olson’s team had previously demon-
äîßDîxlîšDî2302` ̧ø§lUxøäxlî ̧îßxDî

Duchenne in rodents and in human cells in

the laboratory. The new work marks the

‰ßäîäø``xääž³D§Dߐx­D­­D§Í ̧ßä

study, the team focused only on measuring

Çß ̧îxž³§xþx§ßxäî ̧ßDîž ̧³ÍîšDä³ ̧îxĀǧ ̧ßxl

how the intervention might have changed

the dogs’ behavior or day-to-day lives.

ĀD`î§āš ̧ÿ§ ̧³ ̧³xž³¥x`îž ̧³ÿžîš

2302x³xxlžîž³­D`šž³xßā­žšî§Däî

in human Duchenne patients remains

unknown. Olson and his colleagues hope

the intervention might be durable enough

with a single dose, but they need further

ßxäø§îäî ̧xîD`§xDßxßžlxDÍ…ÇDîžx³îä

require more treatments over time, they

might not be able to use the same viral

vehicle, says Elizabeth McNally, a geneti-

cist and cardiologist who directs the Cen-

ter for Genetic Medicine at Northwestern

University. “The body may develop neu-

tralizing antibodies, so there are a lot of

questions about the viral delivery piece

of that,” says McNally, who is also on the

ä`žx³îž‰`Dlþžä ̧ßāU ̧Dßl ̧…'§ä ̧³ÜääǞ³ ̧†

company trying to commercialize this

Duchenne technology but was not involved

with this study.

The sole Duchenne treatment currently

approved … ̧ßîšx7Í3Í­DߦxîD³ž³¥x`î-

able drug made by Sarepta Therapeutics

that requires continuous delivery—increas-

es dystrophin levels by less than 1 percent.

This approach, which has yet to show a clin-

ž`D§Ux³x‰îjlž†xßä…ß ̧­'§ä ̧³Üäž³îšDîžî

ÿ ̧ߦä ̧³2%Éîšx­ ̧§x`ø§xž³î ̧ÿšž`š

%žäxþx³îøD§§āîßD³ä`ߞUxlÊUøî§xDþxä

îšxDU³ ̧ß­D§%äxÔøx³`xø³`šD³xlÍ

ø`šx³³xßxäxDß`šxß­ā=DxßäjD

professor of stem cell biology and regenera-

tive medicine at Harvard University, who is

not involved with developing either therapy,

says these two approaches could potentially

be used in tandem to help boost dystrophin.

Ù³¦žîÜäßxD§§āxĀ`žîž³î ̧äxxä³xÿ

work in mice now translated to a large ani-

mal model,” she says, adding that “the

authors very appropriately note that this is

a preliminary study with a small number of

animals and a short follow-up time.”

Both Sarepta’s approved technology and

'§ä ̧³ÜäxĀÇxߞ­x³îD§ ̧³xîDߐxîDäøUäxî ̧…

the Duchenne population: patients with a

particular dystrophin gene mutation that

D†x`îäDU ̧øî¿ð Çxß`x³î ̧…îš ̧äxÿžîšîšx

disease. There are at least 1,000 such cases

ž³îšx7Í 3 ÍÙ =x³xxlî ̧l ̧§ ̧³îxß­äD…xîā

D³lx‡`D`āäîølžxäž³l ̧äjÚ'§ä ̧³äDāäÍÙî

will be a few years before we’re ready to test

this in humans if it continues to hold up.”

— Dina Fine Maron

MATERIALS SCIENCE

Articial

Wo o d

The synthetic material is

both robust and versatile

A new lightweight substance is as strong

as wood yet lacks its standard vulnerabili-

îžxäî ̧‰ßxD³lÿDîxßÍ

To create the synthetic wood, scientists

took a solution of polymer resin and added

a pinch of chitosan, a sugar polymer derived

from the shells of shrimp and crabs. They

freeze-dried the solution, yielding a struc-

îøßx‰§§xlÿžîšāÇ ̧ßxäD³l`šD³³x§ä

supported by the chitosan. Then they

heated the resin to temperatures as high

as 200 degrees Celsius to cure it, forging

strong chemical bonds.

The resulting material, described in

øøäîž³Science Advances, is as crush-

resistant as wood, says author Shu-Hong

Yu, a materials chemist at the University

of Science and Technology of China in

x…xžÍDäîxß…ßxxąxlßāž³`ßxDîxäxþx³

smaller channels and pores, which further

äîßx³îšx³äîšx­DîxߞD§j?øäDāäÍ³l

higher curing temperatures increase bond-

ing within the resin and increase the mate-

ߞD§Üääîßx³îšjîšxîxD­… ̧ø³lÍllž³

šø­D³­Dlx ̧ß³DîøßD§‰Uxßäî ̧îšx­žĀ

could also help.

Unlike natural wood, the new material

does not require years to grow. Moreover,

it readily repels water—samples soaked in

ÿDîxßD³lž³Däîß ̧³D`žlUDîš… ̧ßðć lDāä

scarcely weakened, whereas samples of bal-

sa wood tested under similar conditions lost

two thirds of their strength and 40 percent

of their crush resistance. The new material

ÿDäD§ä ̧lž‡`ø§îî ̧ž³žîxD³läî ̧ÇÇxlUøß³-

ž³ÿšx³žîÿDäßx­ ̧þxl…ß ̧­îšx‹D­xÍ

The mock wood could be used to make

ding-resistant packaging, says Lennart

Bergström, a materials scientist at Stock-

holm University in Sweden, who was not

ž³þ ̧§þxlž³îšxÿ ̧ߦÍîäÇ ̧ß ̧äžîā§x³lä

an air-trapping capacity that could make

it suitable as an insulation for buildings,

he adds. Eco-friendly alternatives to the

polymer resins also could boost interest in

the material. — Sid Perkins