Parasitic flatworms known as schistosomes afflict more than 200 million people worldwide and can
live in a person's bloodstream for decades. Schistosomes require a gene called cpb1
in order to survive in mice, suggested a new study published in PLOS
Pathogens. The study also shows that schistosome stem cells grow in
response to injury.
Julie Collins and James
Collins of the UT Southwestern Medical Center in Texas have previously
shown that schistosome stem cells restore aging tissue, likely aiding
the parasite's long-term survival. However, it was unclear whether these
stem cells may also help schistosomes recover from injury.
‘Schistosomes require a gene called cpb1 in order to survive in mice, suggested researchers. The study also revealed that schistosome stem cells grow in response to injury.’
To explore this question, the researchers identified schistosome
genes involved in stem cell function and homed in on a gene called cpb1.
They used a technique called RNA interference to reduce expression of
cpb1 in lab-grown schistosomes and found that this resulted in cell
death and organ degeneration in the parasite, as well as dramatic growth
of stem cells.
The scientists hypothesized that cell death triggered by loss of
cpb1 may have been perceived by the parasite as an injury, triggering
stem cell growth to aid tissue repair. Indeed, they observed similar
stem cell growth in schistosomes that had been physically injured.
researchers then tested whether cpb1 is important for schistosomes
living inside mammalian hosts. They used RNA interference to inhibit
expression of cpb1 in schistosomes that were then transplanted into the
blood vessels of mice. They found that schistosomes with reduced cpb1
expression were unable to survive inside the mice.
These findings could improve understanding of the role of stem cells
in schistosome infection and, in the future, they could help inform
development of new treatments. They also demonstrate a new method for
studying schistosome gene function in mice that combines RNA
interference with a classic schistosome transplant technique.
"Schistosomes are on the receiving end of a variety of insults while
living in their human hosts and understanding the parasite's responses
to these injuries may suggest new ways to target these worms. What's
exciting about these results are that schistosome stem cells appear to
be playing a role in responding to injury in the parasite, therefore
getting rid of these stem cells may make the worms incapable or
repairing damaged tissues."