Abstracts LymphForsch 2/2013

Regulation of dermal lymphatics by the developmental control gene WNT5A

K. Buttler, T. Pukrop, J. Becker, J. Wilting, LymphForsch 17 (2) 2013: 62-69

A functioning lymphatic system is essential for tissue fluid homeostasis and the circulation of leukocytes. Primary and secondary lymphedema massively impairs these functions. The molecular etiology of numerous types of primary lymphedema is still unknown. In order to detect new regulators of lymphangiogenesis, apart from the known markers such as Prox1, Lyve-1 and VEGFR-3, we compared human lymphatic endothelial cells (LECs) with umbilical vein endothelial cells (HUVECs) using gene micro-array analyses. We found approximately 1200 regulated genes. These included genes that have not yet been addressed in lymph- angiogenesis, such as the secreted glycoprotein wnt5a. Our investigations of Wnt5a knock- out (KO) mice revealed that Wnt5a regulates the development of dermal lymphatics. In addition to the initial lymphatics, the collectors are also malformed in the homozygous KO mice. At the same time, Wnt5a barely impacts the proliferation of LECs. However, it controls the development of the branching morphology of the lymphatic capillary network and the development of collectors. In the dermis of the KO mice, the lymphatics remain immature and poorly differentiated. We assume that the functionality of lymphatics has not yet been studied in detail in children with WNT5A or ROR2 mutations (Robinow syndrome).

Keywords: Lymphangiogenesis, lymphatic endothelial cell, fluorescence microlymphangiography, Prox1, Wnt5a, Robinow syndrome
Correspondence: Dr. Kerstin Buttler Universitätsmedizin Göttingen Zentrum Anatomie, Institut für Anatomie & Zellbiologie Kreuzbergring 36 D-37075 Göttingen, E-mail: buttler.kerstin@med.uni-goettingen.de

Ultramicroscopic visualization of lymph vessels during embryonic development and in the adult mouse

C. Pollmann, R. Hägerling, M. Andreas, F. Kiefer, LymphForsch 17 (2) 2013: 70-76

In addition to the circulatory blood vascular system, higher vertebrates rely on a second vascular system – the lymphatic vasculature. Lymphatic vessels are indispensable for tissue homeostasis, uptake of lipids and immune cell circulation. Dysfunction of the lymphatic system may result in immune disorders and edema. During embryogenesis, lymphatic endothelial cells (LECs) differentiate from venous blood endothelium by expression of LEC-specific genes. Subsequently, these cells separate from their venous vessels and give rise to primary lymphatic vessels. Previously, visualization of this process was limited to microscopy of histological tissue sec- tions, precluding comprehensive three-dimensional (3-D) reconstruction at cellular resolution. Using light sheet microscopy, we were able to develop a 3-D ultramicroscopic model of initial lymphangiogenesis in the mouse embryo and show that initial LECs leave the cardinal vein as cords of nonlumenized cells forming a meshwork. Cells in the meshwork subsequently aggregate and give rise to the previously unidentified lymphatic structures,the peripheral longitudinal lymphatic vessel (PLLV) and the primordial thoracic duct (pTD). From these lumenized structures, superficial lymphatic vessels sprout to populate other organ systems, including the skin.
As lymphangiogenesis occurs not only during fetal development, but also during adult life under conditions of inflammation, wound healing or tumor formation, intravital visualiza- tion of lymphatics and lymphangiogenic processes is a prerequisite for understanding the physiology and pathophysiology of lymphatic vessels. To address this question, we have generated a LEC-specific reporter mouse, which expresses the fluorescent protein mOrange2 under the control of the lymphatic transcription factor Prox1. Using this Prox1- mOrange2pA reporter line, optical windows such as the mouse dorsal skinfold chamber and 2-photon microscopy, we are now able to perform intravital studies of lymph flow, lymphatic valve formation, maintenance and function.

Keywords: Lymphangiogenesis, mouse embryo, ultramicroscopy, light sheet microscopy, 3-D, lymphendothelial reporter mouse
Correspondence: Prof. Friedemann Kiefer Max-Planck-Institut für Molekulare Biomedizin Röntgenstraße 20 D-48149 Münster, E-mail: fkiefer@gwdg.de

Diagnostic possibilities and limitations of near-infrared imaging of the lymphatic system in the hind leg and tail of mice

Imaging of the lymphatic system in order to develop an animal model for studying secondary lymphedema

K. S. Blum, S. T. Proulx, P. Luciani, J. C. Leroux, M. Detmar LymphForsch 17 (2) 2013: 77-82

A major problem in developing preventive and/or therapeutic treatment options for secondary lymphedema patients is the lack of reliable animal models to study the patho- genesis of lymphedema development. The aim of the current study was to investigate lymphatic flow in the leg and tail of healthy mice with Near-Infrared (NIR)-Imaging with regard to the development of an animal model to study secondary lymphedema. Col- lecting vessels were visualized in all hindlegs, but only in the minority of investigated tails. Lymphatic capillaries were only seen in the tails. Although we imaged lymphatic flow of hindlegs and tails of healthy mice, we conclude that the hindleg is a suitable region to study changes of lymphatic flow in the collecting vessels with NIR-imaging while the tail is more appropriate to study changes of lymphatic flow in lymphatic capillaries.

Keywords: Near-Infrared-Imaging, animal model, lympathic flow, hindleg, tail
Correspondence: Dr. rer. nat. Christian Lentz Universitätsklinikum Bonn, Institut für Medizinische Mikrobiologie, Immunologie und Parasitologie Sigmund-Freud-Straße 25, D-53127 Bonn, E-mail: clentz@uni-bonn.de

Liposuction in patients with benign symmetric lipomatosis (Launois-Bensaude syndrome)

W. Schmeller, A. Baumgartner, LymphForsch 17 (2) 2013: 83-87

Benign symmetric lipomatosis (Launois-Bensaude syndrome) is a rare disease of unknown etiology with a circumscribed increase of subcutaneous adipose tissue in the neck (type I) or in the shoulder girdle and upper arms (type II). In rare cases, it affects the pelvic region (type III), the abdomen (type IV) or other regions (elbows, knees). Type II is the most frequent type. If there are no contraindications, surgical treatment, mainly by liposuction, is the only effective treatment. Due to progression of the disease, recurrences after surgery often occur. In many cases, health insurance companies refuse to reimburse the costs of the operation(s).

Keywords: Benign symmetric lipomatosis, Launois-Bensaude, liposuction
Correspondence: Prof. Dr. med. Wilfried Schmeller Axel Baumgartner Hanse-Klinik, St.-Jürgen-Ring 66, D-23564 Lübeck, E-mail: ws@hanse-klinik.com

Primary lymphedema – long-term study and quality of life in patients undergoing complex physical decongestive therapy

J.Schöhl , J. Rössler , E. Földi, LymphForsch 17 (2) 2013: 88-93

Primary lymphedema can be treated effectively with complex physical decongestive therapy (CDT). CDT includes manual lymph drainage, compression therapy, skin care and exer- cise. CDT is widely reported to be effective in the treatment of acute disease with manual lymph drainage mobilizing the edema in affected extremities. CDT, administered both on an inpatient and an outpatient basis, is also reported to be effective for longterm main- tenance of the condition provided that the patient undertakes regular selfmanagement. Reliable data in this area are sparse, however.
In this retrospective study, the long-term course and the quality of life of patients undergoing CDT were analyzed in detail. The analysis included 452 patients with congenital lymph- edema and lymphedema praecox, who were treated using CDT at the Földi Klinik for up to 26 years. The patientsʼ quality of life was evaluated with a questionnaire. The mean time interval between the onset of symptoms and the initiation of therapy was 4.5 years. The success rate of CDT in the treatment of acute disease in the clinic (Phase I) was >99 %. The continuation of the therapy (Phase II) at home after inpatient treatment, the compliance of patients and the active support of parents were found to be critical factors in the success of long-term therapy. Prophylactic measure was occasionally required to avoid erysipelas as a complication of lymphedema. Regular exercise and the avoidance of overweight were also found to be important. The return rate of the questionnaires was 44.5 %. Approxi- mately 65 % of the patients stated that they had a feeling of heavy extremities and that they had psychological symptoms. More than 40 % reported pain. There was no obvious social impact of the disease or treatment, such as an increased unemployment rate.
In summary, consistently administered CDT was found to eliminate or diminish impairments caused by primary lymphedema and to improve the quality of life in patients. Early and intensive therapy was found to be an important factor for preventing progress of the edema.

Keywords: primary lymphedema, therapy, quality of life
Correspondence: Dr. med. Johanna Schöhl Universitätsmedizin Göttingen Robert-Koch-Straße 40 D-37075 Göttingen, E-mail: johanna.schoehl@med.uni-goettingen.de

The lymphangiogenic growth factors VEGF-C and VEGF-D Part 2: The role of lymphangiogenic growth factors VEGF-C and VEGF-D in lymphatic disorders

R.Krebs, M. Jeltsch, LymphForsch 17 (2) 2013: 96-104

Vascular endothelial growth factor C (VEGF-C) and VEGF-D are the two central signaling molecules that govern the development and growth of the lymphovascular system. The presence or absence of lymphangiogenesis plays a central and sometimes causative role in a variety of diseases. Therefore, molecules that govern lymphangiogenesis, especially VEGF-C and VEGFR-3, offer the possibility for therapeutic interventions. Although the block- ade of lymphangiogenesis does not yet exist as an independent therapeutic concept, a number of anti-lymphangiogenic drugs are now being tested in clinical trials. The rationale is that targeting VEGF-C and VEGFD can improve the current anti-angiogenic treatment, since tumors may deploy the angiogenic forms of VEGF-C and VEGF-D when VEGF-A-medi- ated angiogenesis is blocked therapeutically. Despite numerous attempts, no breakthroughs have occurred in pro-angiogenic thera- pies to date. Furthermore, pro-lymphangiogenic, VEGF-C- or VEGF-D-based, therapies have not yet even entered the clinical trial phase. However, one clinical study with VEGF- C is now in preparation, namely in combination with lymph node transplantation for the treatment of postmastectomy edema. Here, we review the roles that VEGF-C, VEGF-D and their receptors play in diseases involving the lymphatic vascular system, and we present possibilities for utilizing these molecules to stimulate lymphatic vessel growth to treat lymphedema, or to block their functions in order to inhibit tumor angiogenesis and tumor lymphangiogenesis.

Keywords: VEGF-C, VEGF-D, growth factors, lymphangiogenesis, lymphedema, lymphogenic metastasis
Correspondence: PD Dr. Michael Jeltsch Wihuri Research Institute, Institute of Biomedicine and Translational Cancer Biology Program Biomedicum Helsinki Postfach 63 (Haartmaninkatu 8) FIN-00014 Universität Helsinki, Finnland, E-mail: michael@jeltsch.org

Lymphedema: The patientʼs view

S. Helmbrecht, LymphForsch 17 (2) 2013: 105-106

It is not easy for patients with lymphedema to cope with the high demands of therapy. Day in and day out, they do their best, wear compression garments, spend a great deal of time on manual lymph drainage and carefully balance phases of exercise and rest.
Despite all these efforts, the lymph continues to build up and further complications are inevitable. To keep their spirits up, a competent lymphedema network is required that includes experienced doctors, well-trained therapists and bandaging experts, as well as a support group of other patients who share their experience with managing everyday life. All of these groups need to cooperate in order to improve the patientsʻ quality of life as they deal with lymphedema.

Keywords: compliance, competent lymphedema network, lymphedema self-help, quality of life
Correspondence: Susanne Helmbrecht Dipl.-Psych. univ. 1. Vorsitzende Lymphselbsthilfe e.V. Schulstraße 28 D-91074 Herzogenaurach, E-mail: lymphselbsthilfe@arcor.de