Lymphatic Endothelial Cell Defects in Congenital Cardiac Patients With Postoperative Chylothorax

Abstract

Objectives: Chylothorax following cardiac surgery for congenital cardiac anomalies is a complication associated with severe morbidities and mortality. We hypothesize that there are intrinsic defects in the lymphatics of congenital cardiac patients. Methods: Postsurgical chylothorax lymphatic endothelial cells (pcLECs) (n = 10) were isolated from the chylous fluid from congenital cardiac defect patients, and characterized by fluorescent-activated cell sorting, immunofluorescent staining, and quantitative RT-PCR. Results were compared to normal human dermal lymphatic endothelial cells (HdLECs). pcLECs (n = 3) and HdLECs were xenografted into immunocompromised mice. Implants and postoperative chylothorax patient’s pulmonary tissues were characterized by immunostaining for lymphatic endothelial proteins. Results: pcLECs expressed endothelial markers VECADHERIN, CD31, VEGFR2, lymphatic endothelial markers PROX1, podoplanin, VEGFR3, and progenitor endothelial markers CD90 and CD146. However, pcLECs had key differences relative to HdLECs, including altered expression and mislocalization of junctional proteins (VECADHERIN and CD31), and essential endothelial proteins, VEGFR2, VEGFR3, and PROX1. When xenografted in mice, pcLECs formed dilated lymphatic channels with poor cell–cell association. Similar to congenital lymphatic anomalies, the pulmonary lymphatics were dilated in a patient who developed postoperative chylothorax after cardiac surgery. Conclusions: Recent studies have shown that some postoperative chylothoraces in congenital cardiac anomalies are associated with anatomical lymphatic defects. We found that pcLECs have defects in expression and localization of proteins necessary to maintain lymphatic specification and function. This pcLEC phenotype is similar to that observed in lymphatic endothelial cells from congenital lymphatic anomalies. Co-existence of lymphatic anomalies should be considered as a feature of congenital cardiac anomalies.

Roles for RERE in lymphatic endothelial cell proliferation and survival, and human cystic lymphatic malformations

“…There is significant overlap between neuronal, cardiac and lymphatic developmental genes, and RA is a well-established modulator of neuronal differentiation in addition to regulating the earliest stages of lymphangiogenesis (1, 19, 33, 35). Lymphatic endothelial cell dysfunction has also been described in patients with neonatal congenital heart defects and chylothorax (36). The fact that RERE functions have been implicated in lymphatic development, as well as neuronal development, may explain the combination of lymphatic and neurological phenotypes in this case of NEBDEH.…”

Current practices for refractory chylothorax following congenital heart surgery

“…Though there is early compelling data for the use of propranolol in the treatment of chylothorax, only two centres report its use in current practice for post-operative chylothorax. Researchers at Columbia showed significant similarities between the lymphatic endothelial cells of patients with congenital lymphatic abnormalities and those with post-operative chylothorax [15][16][17] , prompting clinical study of the utility of propranolol in refractory postoperative chylothorax. 18 Corda and colleagues reported a retrospective cohort of 25 patients with high-volume postoperative chest tube output who received propranolol, and when compared to matched controls, there was an association with clinical improvement.…”