Israeli team succeed in growing an engineered human lymphatic vessel network in a lab that could eventually benefit lymphedema patients
Lymphedema refers to swelling that generally occurs in one of the arms or legs or sometimes both. The condition is most commonly caused by the removal of or damage to tje lymph nodes as a part of cancer treatment and results from a blockage in your lymphatic system (part of the immune system). The blockage prevents lymph fluid from draining well, and the fluid buildup leads to swelling.
While there is presently no cure for lymphedema, common treatments that provide partial improvement include compression of the affected limb and massage. In severe cases, bypass surgery is prescribed. If diagnosed late or left untreated, it can be painful and cause harm to the body.
Scientists at the Technion-Israel Institute Of Technology in Haifa have managed to grow an engineered human lymphatic vessel network. Published in PNAS ([US] Public Library of Science) under the title “Investigating lymphangiogenesis in vitro and in vivo using engineered human lymphatic vessel networks,” the study was led by postdoctoral fellow Dr. Shira Landau and conducted in the lab of Prof/ Shulamit Levenberg of the Technion’s Faculty of Biomedical Engineering.
The significance of the researchers’ findings lies in a better understanding of lymphatic vessel generation, which could have implications for treatment of lymphedema and the generation of more lifelike tissue flaps.
The swelling caused by lymphedema ranges from mild, hardly noticeable changes in the size of the arm or leg to extreme changes that make the limb hard to use. Lymphedema caused by cancer treatment may not occur until months or years after treatment.
The lymphatic system is vital for keeping the body healthy, as it circulates protein-rich lymph fluid in vessels throughout your body, collecting bacteria, viruses and waste products. These are taken to the lymph nodes and filtered out by lymphocytes – infection-fighting cells that live in the lymph nodes and are ultimately flushed from the body.
Any condition or procedure that damages your lymph nodes or lymph vessels can cause lymphedema. Causes include removal of or injury to lymph nodes and lymph vessels (for example, lymph nodes may be removed to check for the spread of breast cancer, and lymph nodes may be injured in surgery that involves blood vessels in your limbs); radiation treatment for cancer; if cancer cells block lymphatic vessels, lymphedema may result; and an infection of the lymph nodes or parasites can restrict the flow of lymph fluid.
Lymphedema in your arm or leg can lead to serious complications, such as infections. Possible infections that can result from lymphedema include a serious bacterial infection of the skin (cellulitis) and an infection of the lymph vessels (lymphangitis). The smallest injury to your arm or leg can be an entry point for infection.
To avoid complications, protect your arm or leg; rest your arm or leg while recovering from cancer treatment; avoid heat on your arm or leg but elevate it whenever possible; keep the affected limb clean; and avoid tight clothing that could constrict your arm or leg
In the lab, Landau and her coresearchers grew human lymphatic vessels, together with blood vessels and supporting cells, creating engineered tissue with a functioning vessel network. This was done from inner-lining cells of lymphatic vessels, together with blood vessels respectively, together with support cells, all seeded on sheets of collagen – the main structural protein of the body’s connective tissue – their engineered tissue mimics as closely as possible the body’s natural structures.
From this seemingly simple starting point, the group had within a few days a network of vessels that displayed both the arrangement and the functionality expected of them in the body. The engineered tissue was further implanted into a mouse and successfully integrated with the mouse’s lymph and blood vessels.
This success at the Technion has multiple implications. First, the platform they grew would facilitate the study of lymphatic vessels, their formation and the factors that affect them. Second, lymphedema could in the future be treated by implanting a functional network of smaller and larger lymph vessels that would merge with the host’s system, all grown from the patient’s own cells, eliminating fear of rejection.
Third, engineered tissue flaps – units containing multiple tissues necessary for transplantation such as muscle, blood vessels, and connective tissue – could be made more lifelike, containing lymph vessels as well. This would improve the implant’s integration and speed up healing.
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