Lecture by Kari Alitalo, laureate of the 2014 Dr A.H. Heineken Prize for Medicine.
The milky vessels rediscovered, more than just a drain
The lymphatic vessels were first described by Gaspare Aselli, an Italian physician who described these ‘milky vessels’ in his book Lacteis venis published in Milan in 1627. These vessels were poorly visible for pathologists as they did not contain red blood cells, so they were largely dismissed as a mere drainage system for centuries, obtained some renewed interest in the beginning of the past century, and again neglected until recently, when growth factors that can generate and maintain these vessels were discovered.
Today, the lymphatic vessels are considered much more sophisticated, participating in many important functions of the body. Besides collecting fluid that has leaked into tissues from the bloodstream and returning it to the blood, they also provide immune surveillance process to detect pathogens in bodily fluids by sending the fluid through lymph nodes where key cells of the immune system help to mount an immune response towards the intruders.
The lymphatic vessels have also emerged as central players in numerous diseases, such as cancer, inflammatory and infectious diseases, glaucoma, which can endanger vision in the eye, and the disfiguring swelling known as lymphedema. Discoveries on how lymphatic vessels grow and function have provided researchers ways to intervene with the pathological processes in disease, for example to reduce the spread of tumours, to boost the efficiency of vaccines, or to treat lymphedema by building new lymphatic vessels in place of those damaged for example by surgery to remove breast cancer metastases from the armpit.
Some of these treatments are currently undergoing phase I clinical (safety) trials for drug development. Because lymphatic vessels are less well known than blood vessels and there there is still so much to discover, many laboratories are switching from the study of blood vessels to the research on the lymphatic system. In my talk I will outline these striking developments and their importance for the development of improved therapy of several diseases.