15 January 2022 | New Scientist | 23News
IMMUNE cells in the bodies
of mice have been temporarily
reprogrammed to repair damaged
hearts by removing scar tissue,
thanks to the technology used in
the mRNA coronavirus vaccines.
“After you give the treatment,
the scar goes away,” says Haig
Aghajanian at the University
of Pennsylvania.
Genetically engineered
immune cells called CAR T-cells
are already used to treat cancer,
but this method is very expensive.
The mRNA approach, which
involves only temporarily
modifying these cells, could
dramatically decrease costs.
“We’re hoping this is the
next step in CAR-T-type
technology that will allow
more access,” says Aghajanian.
T-cells are immune cells that
use receptors on their surface
to recognise cells infected with
viruses, which they then destroy.
T-cells can be reprogrammed to
target any desired cell type by
giving them the right receptor.
Conventional CAR T-cells
are made by taking T-cells from
a person’s body, genetically
engineering them to add a gene
for a “chimeric antigen receptor”
(hence the name) and then
returning them to the body.
Such treatments can be effective
against cancers of the blood such
as leukaemia, but the first CAR-T
treatment to get approved,
called Kymriah, cost $475,000.
Aghajanian’s team is instead
turning T-cells into CAR T-cells
without removing them from the
body, by delivering genes in the
form of mRNAs. The mRNAs are
packaged inside the same fatty
balls, called lipid nanoparticles,
used in the Pfizer/BioNTech and
Moderna coronavirus vaccines.
In this case, however, the lipid
nanoparticles have antibodiesattached to them that bind to
T-cells. The team was already
working on this before the
pandemic, but Aghajanian says
the mass roll-out of vaccines
should make it easier to get
other uses of lipid nanoparticles
approved by regulators.Other teams have tried to create
CAR T-cells inside the body by
using viruses to permanently
add DNA genes to the genomes
of T-cells. This is potentially
risky if something goes wrong.
mRNAs, by contrast, are
temporary copies of genes used
as templates by protein-making
factories. They aren’t integrated
into the genome and only persist
for days. This means an mRNAdoesn’t permanently alter T-cells.
“It does its thing for a few days and
then it is gone,” says Aghajanian.
His team has used this approach
to target the cells that lay down
collagen, which our bodies
constantly produce and then
remove with other cells. After
an injury, the cells that lay down
collagen overproliferate, leading
to a scar. “If you can get rid of
these cells, it goes back into
balance and the scar quickly
recedes,” says Aghajanian.
To test the method, his team
damaged the hearts of mice to
create scarring, or fibrosis, that
impairs the contraction and
relaxation of the heart. Two
weeks after an infusion of mRNA
nanoparticles, the amount of
scar tissue in the hearts of the
mice was nearly half of that in
untreated animals, and their heart
function improved significantly
(Science, doi.org/gn2gzm). ❚Medicine
Michael Le Page
Broken hearts in mice repaired using
mRNA coronavirus vaccine technology
“ T-cells can be
reprogrammed to target
any cell type by giving
them the right receptor”Botany
A TROPICAL, evergreen tree from
Cameroon, the first plant species
to be named as new to science in
2022, has officially been labelled
Uvariopsis dicaprio in honour of
the actor Leonardo DiCaprio.
Martin Cheek at the UK’s Royal
Botanic Gardens, Kew, and his
colleagues – including researchers
at the National Herbarium of
Cameroon and the University of
Yaoundé I, Cameroon – analysed
photos and specimens of the tree,
which is found in Cameroon’s
tropical Ebo forest.
They determined that it was
previously unknown to science, and
also appears to be unknown among
local communities. The team
named the species after actor and
environmental activist DiCaprio to
commemorate his efforts to protect
Ebo forest from logging.
Standing at around 4 metres
tall, U. dicaprio can be identified by
the distinctive and glossy yellow-green flowers that grow on its
trunk. It is closely related to the
ylang-ylang tree (Cananga odorata)
which is native to India, South-East
Asia, the Philippines, Indonesia and
Australia (PeerJ, doi.org/hb7n).
“This is a plant which, for a
botanist, just jumps out at you,”says Cheek. “It’s so spectacular.”
Currently, fewer than 50
individual specimens have been
spotted, all in a single, unprotected
area of Ebo forest. As a result,
U. dicaprio is critically endangered.
The tree adds to the list of
strange and spectacular plants
that have been revealed in the
past 12 months. During that time,
many other plant species have
been newly named. For instance, in
August 2021, Mark Chase, also at
Royal Botanic Gardens, Kew, and his
colleagues officially labelled seven
new Australian species of wild
tobacco (Nicotiana), including one
that traps and kills small insects. ❚Newly identified tree
species named after
Leonardo DiCaprio
Chen LyUvariopsis dicaprio,
a distinctive new tree
species from CameroonLORNA^ MACKINNON^