Scientists
investigating the causes of lymphoedema have made a major discovery,
revealing that lymphatic vessels can produce red and white blood cells.
Until now, it was believed that blood cells derived solely from stem cells found in bone marrow.
The discovery, made by an international team has been published in Nature, the world’s leading multidisciplinary science journal.
Researchers made the connection when investigating the causes of
lymphoedema – a blockage in the lymphatic system resulting in swelling
in the arm or leg, which is very difficult to treat.
Lymphatic vessels are a key component of the cardiovascular system,
responsible for returning excessive tissue fluid and protein (lymph)
back to the bloodstream and forming a major part of the immune system
that defends the body against harmful bacteria or viruses.
The researchers traced defects in the lymphatic vessels to cells being incorrectly programmed during development.
“We discovered a site in DNA important for controlling genes that
program the identity and development of lymphatic vessels,” the senior
author says.
“If these genes aren’t switched on at the correct time and place,
lymphatic vessels don’t form properly, causing lymph fluid to leak back
into the tissues, leading to swelling (lymphoedema). In an unexpected
discovery, we identified that the same gene that controls the
development of lymphatic vessels also controls the production of blood
cells.
“This exciting discovery suggests that lymphatic vessels may be a
previously unrecognised source of blood cells both during development
and in disease.”
The ability of lymphatic vessels to produce blood cells could be
important for fighting infection and may play a role in some blood
cancers.
The researchers will now investigate what triggers lymphatic vessels to
produce different types of blood cells and when this occurs – during
normal development as well as during disease.
https://www.nature.com/articles/s41586-022-05650-9