Abstract 20600: Visualization of Flow and Movement of Lymphatic Valves in Biological Pumps Made From Engineered Heart Tissue

Introduction: At present, the arsenal of approaches to treat lymphedema is very limited and new therapies to improve lymph drainage are critically needed. We aim to address this need using newly available tools of tissue engineering. Specifically, we propose to create a regularly contracting layer of cardiomyocytes around thoracic duct and other major lymphatic vessels creating tissue engineered lymph heart. Methods: Tissue engineered cardiac fibers were made of rat neonatal cardiac myocytes mixed with fibrin hydrogel and seeded in rectangular agarose molds. The fibers ranged from 100 to 200 micron diameter and 1-2 cm in length and were amendable to surgical manipulation. Lymphatic system was visualized using tissue injection of indocyanine green dye and infrared sensitive CCD-camera. Movement of lymphatic valves was observed using Zeiss LSM 510 confocal imaging system using fluorescent membrane dyes. Results: Excised segments of rat and rabbit thoracic duct with and without valves were wrapped with engineered cardiac fibers creating coil-like structures. The latter exhibited spontaneous contractions and were paceable using external electrodes. Contractions caused recordable movements of lymphatic valve leaflets and associated changes in flow. Conclusions: Our data show the feasibility of surrounding segments of major lymphatic conduits, including thoracic duct, with rhythmically beating sheaths of cardiac muscle. Clinically, such biological pumps can be made from cardiomyocytes derived from patient’s own stem cells.