WASHINGTON: In a breakthrough which
could pave the way for regenerating human lungs, scientists claim to have
successfully implanted laboratory-cultivated cells into a rat's
lungs.
Lung tissue is difficult to regenerate as it does not
generally repair or regenerate beyond the microscopic level. The only current
way to replace damaged adult lung tissue is to perform lung transplantation,
which is highly susceptible to organ rejection and infection.
Now, a
team at Yale University successfully implanted tissue-engineered lungs, cultured
in vitro, which could serve the lung's primary function of exchanging oxygen and
carbon dioxide, the 'Science Express' reported.
The scientists took
adult rat lungs and first removed their existing cellular components, preserving
the extracellular matrix and hierarchical branching structures of the airways
and vascular system to use later as scaffolds for the growth of new lung
cells.
They then cultured a combination of lung-specific cells on the
extracellular matrix, using a novel bioreactor designed to mimic some aspects of
the fetal lung environment.
Under the fetal-like conditions of the
bioreactor, the cells repopulated the decellularised matrix with functional lung
cells. When implanted into rats for short intervals of time (45-120 minutes),
the engineered lungs exchanged oxygen and carbon dioxide similarly to natural
lungs.
Lead scientist Laura Niklason said: "We succeeded in
engineering an implantable lung in our rat model that could efficiently exchange
oxygen and carbon dioxide, and could oxygenate hemoglobin in the blood. This is
an early step in the regeneration of entire lungs for larger animals and,
eventually, for humans."
The scientists found the mechanical
characteristics of the engineered lungs were similar to those of native tissues
and, when implanted, were capable of participating in gas exchange, which is the
primary role of lungs.
"Seeded and cultured epithelium displays
remarkable hierarchical organization within the lung matrix, while seeded
endothelial cells efficiently repopulate lung vasculature," Niklason
said.
According to the scientists, this is an important first step,
but a great deal more research must be done to see if functional lungs can be
regenerated in vitro, implanted and sustained in their
functioning.
Niklason said that for this technology to be applicable
to patients, it is likely that years of research with adult stem cells will be
needed to repopulate lung matrices and produce fully functional
lungs.
|
