Generation and characterization of a mouse lymphatic endothelial cell line.

Lymphatic vessels, by channeling fluid and leukocytes from the periphery into lymph nodes, play a central role in the development of the immune response. Despite their importance in homeostasis and disease, the difficulties in enriching and culturing lymphatic endothelial cells limit studies of their biology. Here, we report the isolation, stabilization, and characterization of a mouse lymphatic endothelial cell line (MELC) and the generated clones thereof. Cells were isolated from benign lymphangiomas induced by intraperitoneal injections of incomplete Freund's adjuvant. The MELC line expressed molecules typical of lymphatic endothelium, including VEGFR3/Flt-4, podoplanin, Prox-1, and D6, but not LYVE-1. It also expressed CD34, ICAM-1, VCAM, and JAM-A, but not CD31, VE-cadherin, E-selectin, or CX3CL1/fractalkine (both TNFalpha-induced), at variance with vascular endothelial cells tested in parallel. The inflammatory cytokines TNFalpha and IL-4 regulated production of selected adhesion molecules (VCAM), cytokines (IL-6), and chemokines (CCL2/JE). Whole genome transcriptional profiling identified a set of 150 known genes differentially expressed in MELC versus vascular endothelial cells. Thus, the MELC line may represent an invaluable source of lymphatic endothelium.

Lymphatic endothelial tumors induced by intraperitoneal injection of incomplete Freund's adjuvant.

Endothelial cells form the inner lining of blood and lymphatic vessels. In mice, only tumors of the blood vessel endothelium (haemangiomas) have been thus far reported. Here we describe a highly reproducible method for the induction of benign tumors of the lymphatic endothelial cells (lymphangiomas) in mice by intraperitoneal injection of incomplete Freund's adjuvant. Morphological and histopathological studies of the lesions revealed the presence of cells at various levels of vascular development. The lymphangiomas developed in the peritoneal cavity and expressed the endothelial markers CD31/PECAM (platelet endothelial cell adhesion molecule), CD54/ICAM-1 (InterCellular Adhesion Molecule-1), and CD102/ICAM-2, as well as the vascular endothelial growth factor (VEGF) receptor Flk-1, the endothelial cell specific receptors Tie-1 and Tie-2 and the lymphatic endothelial cell specific Flt4 receptor as shown by in situ hybridization. The Flk-1 and Flt4 receptors were also identified in immunoblots of the tumors and in cells cultured from them. When induced in beta-galactosidase knock-in Flt4(+/-) mice, the tumor endothelia could be stained blue in a number of tumor cells although the staining was of lower intensity than in normal lymphatic vessels. The tumor-derived cells could be propagated in vitro and they spontaneously differentiated, forming vessel-like structures. Murine lymphangiomas thus represent a highly reproducible and convenient source of lymphatic endothelial cells.

Complications of low-dose heparin prophylaxis following pelvic lymphadenectomy.

All patients who underwent pelvic lymphadenectomy for prostatic carcinoma over a five-year period were reviewed to evaluate the effect of minidose heparin prophylaxis on lymphocele formation and postoperative complications. The overall incidence of complications was found to be consistent with that reported in the current literature. However, when the rate of lymphocele occurrence was correlated with perioperative minidose heparin therapy, the incidence rose from 2.5 per cent in those receiving no heparin to 38 per cent in patients receiving both pre- and postoperative prophylactic heparinization. Other major postoperative complications were also significantly increased when minidose heparin was pre- or postoperatively administered. A strong recommendation is made for caution in the routine use of prophylactic low-dose heparin during pelvic surgery.

Prophylactic anticoagulation as a possible cause of inguinal lymphocyst after radical vulvectomy and inguinal lymphadenectomy.

From 1957 to 1982, 115 patients underwent radical vulvectomy and bilateral inguinal lymphadenectomy for invasive squamous carcinoma of the vulva. From 1957 to 1971, 57 patients received perioperative prophylactic sodium warfarin (Coumadin) as prophylaxis against pulmonary embolism. From 1971 to 1976, 27 consecutive patients received dextran-40 as prophylaxis for pulmonary embolism and to improve the microcirculation to the inguinal skin flaps. Because of the report that dextran-40 is a cause of acute renal failure, this study was terminated and the subsequent 19 patients were treated with mini-dose heparin because of the reported benefit as prophylaxis against thromboembolic disease. During the 25-year period, 12 patients received no prophylactic anticoagulants. Mini-dose heparin resulted in a significant morbidity not previously reported in patients undergoing inguinal lymphadenectomy: 43% (8/19) of the mini-dose heparin patients, 7% (2/27) of the dextran-40 patients, 0% (0/57) of the sodium warfarin patients, and none of the 12 patients not receiving perioperative prophylaxis developed inguinal lymphocysts (P less than .001). There was no significant difference in the prevention of pulmonary embolism between the mini-dose heparin (0/19), dextran-40 (0/27), and no treatment groups (0/12) as compared to the 5% (3/57) incidence in the sodium warfarin patients (.10 less than P less than .50). The significant relationship between prophylactic heparin and the subsequent development of inguinal lymphocysts and the need to reassess its role in prevention of pulmonary embolism in patients undergoing lymphadenectomy is discussed.

An experimental study of intraoral carcinogenesis in rats.

A new method has been devised for preparing artificial cecal pouches lined with mucous epithelium in the lower lips of Wistar and Sprague-Dawley rats in order to make carcinogens act continuously for a long time in the oral mucosa. When a 0.5 per cent mineral oil solution of DMBA, a crystal of MC, and a crystal of NG were administered, squamous-cell carcinoma, carcinoma in situ, papilloma, adenoma sebaceum. neurofibroma, fibroma, hemangiosarcoma, hemangiosarcoma, hemangioma, and lymphangioma were successfully produced in the oral mucosa of rats. In addition, interesting findings were obtained concerning tissue changes in the process of carcinogensis in the mucous epithelium.