Lymphedema and therapeutic lymphangiogenesis

The microenvironment of secondary lymphedema. The key to finding effective treatments?

Lymphedema is characterized by the swelling of extremities due to the accumulation of interstitial fluids. It is a painful and devastating disease that increases the risk of infections and destroys patients' quality of life. Secondary lymphedema is caused by damage to the lymphatic system due to infections, obesity, surgery, and cancer treatments. This damage fails to be repaired and leads to fluid accumulation, tissue remodeling, inflammation, and ultimately fibrosis. The lymphedema microenvironment is altered by stress, immune dysfunction, and changes in metabolism. Stress in the microenvironment includes increased hypoxia and oxidative stress but how this contributes to lymphedema progression is unclear. The immune system plays a critical role in lymphedema through T cell helper type 2 (Th2) immune responses and the infiltration of macrophages into lymphedematous tissue. The inflammatory cytokines released by immune cells lead to tissue remodeling and fibrosis. There are also changes in metabolism in the lymphedema microenvironment with altered lipid oxidation, ketone body oxidation, and glycolysis. How these changes affect lymphedema and treatment interventions has been the focus of clinical trials. Lymphedema is also associated with cancer and obesity through damage to the lymphatic system. This review will illustrate microenvironmental changes in lymphedema and how this relates to cancer and obesity. In addition, we will discuss new therapeutic strategies to treat lymphedema. Finally, we will address the prospects of lymphedema research in the context of the microenvironment.

Factors Predicting the Effect of a Complex Decongestive Therapy in Patients with Mild Lymphedema Following Mastectomy for Early Stage Breast Cancer

Background: Complex decongestive therapy (CDT) is being used in breast cancer-related lymphedema (BCRL). The degree of initial edema and bioimpedance analysis (BIA) are known to be related with the therapeutic effect of CDT. D-dimer can indirectly reflect lymphangiogenesis because IL-6 regulates D-dimer and vascular endothelial growth factor, which is the most important lymphangiogenic factor. We assessed whether D-dimer could be used for the prediction of therapeutic effect of CDT, as well as BIA and initial edema. Methods: The participants were patients who took inpatient treatment for BCRL from July 2016 to May 2020. Percent excess volume (PEV) was calculated by dividing the difference in volume of both arms by the edema arm, and the difference in PEV before and after 2 weeks of CDT was defined as the CDT effect. BIA and D-dimer tests were performed before treatment. Results: The single frequency bioimpedance analysis (SFBIA) ratio and D-dimer showed significant correlations with β coefficients of 0.581 and 0.402 (p < 0.01), respectively, and the explanatory power of these models was confirmed to be 0.704.The areas under the curve of initial PEV, SFBIA ratio, D-dimer for determining the CDT effect were identified as 0.849, 0.795, and 0.725, respectively. Conclusions: Initial PEV, SFBIA ratio, and blood D-dimer levels could be used as predictors for CDT treatment effect. Their usefulness order was in the order of initial PEV, SFBIA ratio, and D-dimer. These factors could be used as predictors to establish therapeutic plan in patients with mild lymphedema.

Relation Between Characteristics of Indocyanine Green Lymphography and Development of Breast Cancer-Related Lymphedema

Background: Breast cancer-related lymphedema (BCRL) is a disabling and frequently occurring condition after treatment for breast cancer. Studying lymph anatomy by means of indocyanine green (ICG) lymphography is a promising tool to help better understand BCRL. The aim of this study is to investigate the relation between ICG lymphography characteristics and the risk of developing BCRL. Methods and Results: Patients scheduled for breast surgery with either unilateral axillary lymph node dissection or sentinel lymph node biopsy between November 2017 and May 2019 were included. Patients were assessed at baseline and up to 36 months postsurgery. BCRL was defined as an increase of ≥5% relative arm volume difference compared with the presurgical difference. In total, 128 patients were included. During 36 months of follow-up, 45 patients (35.2%) developed BCRL. The number of lymph vessels before surgery was not a statistically significant risk factor for developing BCRL (p = 0.8485). However, an increase in the number of lymph vessels compared with baseline was a significant protective factor for developing BCRL (odds ratio = 0.8). An increase of one lymph vessel corresponds to a 19% relative risk reduction of developing BCRL. The presence of lymph nodes at baseline and the change in the presence of lymph nodes compared with baseline were no predictors for the development of BCRL (p = 0.0986 and p = 0.8910, respectively). Conclusions: An increase in the number of lymph vessels visualized by ICG lymphography compared with baseline is a protective factor for developing BCRL. Therapies with the ability to increase the number of lymph vessels can thus possibly decrease the risk of developing BCRL.

Sentinel node restoration by vascularized lymph node transfer in mice

BACKGROUND

Recent reports have indicated that vascularized lymph node transfer (VLNT) may improve the impaired immunity in lymphedema but there has been no report concerning anti-cancer immunity. In the early tumor immune response, dendritic cells (DCs) participate in tumor recognition and antigen presentation in local lymphatics. Here, we investigated the impact of VLNT on DC dynamics against cancer in mouse models.

METHODS

Forty-seven 8-week-old C57BL/6 N male mice were divided into three surgical groups: a VLNT model in which a vascularized inguinal lymph node (LN) flap was transferred into the ipsilateral fossa after a popliteal LN was removed; a LN dissection (LND) model in which the popliteal LN was dissected; and a control model in which a skin incision was made at the popliteal fossa and an ipsilateral inguinal LN was removed. Postoperative lymphatic flows were observed by indocyanine green lymphography and B16-F10-luc2 mouse melanoma were implanted into the ipsilateral footpad. The proportion of DCs in the transplanted nodes was measured by CD11c immunohistochemistry using digital imaging analysis 4 days after cancer implantation. Metastases to the lungs and LNs were quantitatively evaluated by luciferase assay 4 weeks after cancer implantation.

RESULTS

After VLNT, lymphatic reconnection was observed in 59.2% of mice. The proportion of DCs was significantly higher in the VLNT group with lymphatic reconnection (8.6% ± 1.0%) than in the naïve LN (4.3% ± 0.4%) (p < .001). The tumor burden of lung metastases was significantly less in the VLNT group with lymphatic reconnection compared with the LND group (p = .049).

CONCLUSIONS

Metastasis decreased in mice with reconnected lymphatics after VLNT. A possible explanation was that lymphatic restoration may have contributed to the tumor immune response by allowing DC migration to LNs.

Accessory Lymphatic Drainage Pathways on Indocyanine Green Lymphography in Patients with Breast Cancer-Related Lymphedema

BACKGROUND

Current predictive models of lymphedema risk cannot predict with 100% certainty which patients will go on to develop lymphedema and which will not. Patient-specific anatomic and physiologic differences may be the missing factor. The authors hypothesize that patients with accessory lymphatic pathways may have improved lymphatic drainage, resulting in smaller limb volumes.

METHODS

The authors reviewed indocyanine green (ICG) lymphography images of all patients who presented to their institution for evaluation of breast cancer-related lymphedema. Patients with unilateral upper extremity lymphedema, a full set of bilateral limb measurements, and ICG images of both limbs were included. Other variables of interest included patient demographics and length of follow-up. Patients with accessory pathways were determined independently, and conflicts were resolved with discussion. Abnormal images were also evaluated for common drainage pathways.

RESULTS

Thirty patients were identified as having accessory lymphatic drainage pathways. These patients had significantly smaller limb volume differences [8.19% (SD, 11.22)] compared with patients who did not exhibit these pathways [20.74% (SD, 19.76); P < 0.001]. The most common pathway was absence or rerouting of the radial bundle to the ulnar or volar bundles ( n = 16).

CONCLUSIONS

The ability to create accessory lymphatic drainage pathways may be associated with improved lymphatic drainage, resulting in smaller limb volumes. Furthermore, certain drainage pathways appear to be more common than others. Description of these pathways should be considered for inclusion in ICG lymphography image grading criteria. Further study is needed to clarify the nature of these pathways and whether these pathways affect subjective symptoms and quality of life.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Mechanical forces in lymphatic vessel development: Focus on transcriptional regulation

The lymphatic system is crucial for the maintenance of interstitial fluid and protein homeostasis. It has important roles in collecting excess plasma and interstitial fluid leaked from blood vessels, lipid absorption and transportation in the digestive system, and immune surveillance and response. The development of lymphatic vessels begins during fetal life as lymphatic endothelial progenitor cells first differentiate into lymphatic endothelial cells (LECs) by expressing the master lymphatic vascular regulator, prospero-related homeobox 1 (PROX1). The lymphatic vasculature forms a hierarchical network that consists of blind-ended and unidirectional vessels. Although much progress has been made in the elucidation of the cellular and molecular mechanisms underlying the formation of the lymphatic vascular system, the causes of lymphatic vessel abnormalities and disease are poorly understood and complicated; specifically, the mechanistic basis for transcriptional dysregulation in lymphatic vessel development remains largely unclear. In this review, we discuss the recent advances in our understanding of the molecular and cellular mechanisms of lymphatic vascular development, including LEC differentiation, lymphangiogenesis, and valve formation, and the significance of mechanical forces in lymphatic vessels, with a focus on transcriptional regulation. We also summarize the current knowledge on epigenetic mechanisms of lymphatic gene expression.

Plexin D1 negatively regulates zebrafish lymphatic development

Lymphangiogenesis is a dynamic process that involves the directed migration of lymphatic endothelial cells (LECs) to form lymphatic vessels. The molecular mechanisms that underpin lymphatic vessel patterning are not fully elucidated and, to date, no global regulator of lymphatic vessel guidance is known. In this study, we identify the transmembrane cell signalling receptor Plexin D1 (Plxnd1) as a negative regulator of both lymphatic vessel guidance and lymphangiogenesis in zebrafish. plxnd1 is expressed in developing lymphatics and is required for the guidance of both the trunk and facial lymphatic networks. Loss of plxnd1 is associated with misguided intersegmental lymphatic vessel growth and aberrant facial lymphatic branches. Lymphatic guidance in the trunk is mediated, at least in part, by the Plxnd1 ligands, Semaphorin 3AA and Semaphorin 3C. Finally, we show that Plxnd1 normally antagonises Vegfr/Erk signalling to ensure the correct number of facial LECs and that loss of plxnd1 results in facial lymphatic hyperplasia. As a global negative regulator of lymphatic vessel development, the Sema/Plxnd1 signalling pathway is a potential therapeutic target for treating diseases associated with dysregulated lymphatic growth.

Hydrogen Sulfide Attenuates Lymphedema Via the Induction of Lymphangiogenesis Through a PI3K/Akt‐Dependent Mechanism

Background

Accumulating evidence suggests that hydrogen sulfide ( H 2 S ), an endogenously produced gaseous molecule, plays a critical role in the regulation of cardiovascular homeostasis. However, little is known about its role in lymphangiogenesis. Thus, the current study aimed to investigate the involvement of H 2 S in lymphatic vessel growth and lymphedema resolution using a murine model and assess the underlying mechanisms.

Methods and Results

A murine model of tail lymphedema was created both in wild‐type mice and cystathionine γ‐lyase–knockout mice, to evaluate lymphedema up to 28 days after lymphatic ablation. Cystathionine γ‐lyase–knockout mice had greater tail diameters than wild‐type mice, and this phenomenon was associated with the inhibition of reparative lymphangiogenesis at the site of lymphatic ablation. In contrast, the administration of an H 2 S donor, diallyl trisulfide, ameliorated lymphedema by inducing the formation of a considerable number of lymphatic vessels at the injured sites in the tails. In vitro experiments using human lymphatic endothelial cells revealed that diallyl trisulfide promoted their proliferation and differentiation into tube‐like structures by enhancing Akt (protein kinase B) phosphorylation in a concentration‐dependent manner. The blockade of Akt activation negated the diallyl trisulfide–induced prolymphangiogenic responses in lymphatic endothelial cells. Furthermore, the effects of diallyl trisulfide treatment on lymphangiogenesis in the tail lymphedema model were also negated by the inhibition of phosphoinositide 3'‐kinase (P13K)/Akt signaling.

Conclusions

H 2 S promotes reparative lymphatic vessel growth and ameliorates secondary lymphedema, at least in part, through the activation of the Akt pathway in lymphatic endothelial cells. As such, H 2 S donors could be used as therapeutics against refractory secondary lymphedema.

Acquired lymphedema: Molecular contributors and future directions for developing intervention strategies

Lymphedema is a debilitating chronic disease that mostly develops as an adverse reaction to cancer treatment modalities such as chemotherapy, surgery, and radiotherapy. Lymphedema also appears to be a deteriorating consequence of roundworm infections, as best represented by filariasis. According to its origin, lymphedema is classified as primary lymphedema and acquired lymphedema. The latter is an acquired condition that, hitherto, received a considerably low attention owing to the less number of fatal cases been reported. Notably, despite the low mortality rate in lymphedema, it has been widely reported to reduce the disease-free survival and thus the quality of life of affected patients. Hence, in this review, we focused on acquired lymphedema and orchestration of molecular interplays associated with either stimulation or inhibition of lymphedema development that were, in vast majority, clearly depicted in animal models with their specific and distinct technical approaches. We also discussed some recent progress made in phytochemical-based anti-lymphedema intervention strategies and the specific mechanisms underlying their anti-lymphedema properties. This review is crucial to understand not only the comprehensive aspects of the disease but also the future directions of the intervention strategies that can address the quality of life of affected patients rather than alleviating apparent symptoms only.

How we approach lymphedema in the pediatric population

Lymphedema in children is rare; however, it is usually a progressive and chronic condition. Accurate diagnosis of lymphedema in the pediatric population often takes several months and sometimes is delayed for years. Lymphedema can be isolated or associated with genetic syndromes, thus it is very important to identify the correct diagnosis, to select carefully which patients to refer for genetic testing, and to initiate appropriate treatment in a timely fashion. In this article, we review key information about diagnosis of lymphedema, associated conditions and syndromes, and current treatment modalities.

How we approach lymphedema in the pediatric population

Lymphedema in children is rare; however, it is usually a progressive and chronic condition. Accurate diagnosis of lymphedema in the pediatric population often takes several months and sometimes is delayed for years. Lymphedema can be isolated or associated with genetic syndromes, thus it is very important to identify the correct diagnosis, to select carefully which patients to refer for genetic testing, and to initiate appropriate treatment in a timely fashion. In this article, we review key information about diagnosis of lymphedema, associated conditions and syndromes, and current treatment modalities.

Lymphatic Vessel Regression and Its Therapeutic Applications: Learning From Principles of Blood Vessel Regression

Aberrant lymphatic system function has been increasingly implicated in pathologies such as lymphedema, organ transplant rejection, cardiovascular disease, obesity, and neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. While some pathologies are exacerbated by lymphatic vessel regression and dysfunction, induced lymphatic regression could be therapeutically beneficial in others. Despite its importance, our understanding of lymphatic vessel regression is far behind that of blood vessel regression. Herein, we review the current understanding of blood vessel regression to identify several hallmarks of this phenomenon that can be extended to further our understanding of lymphatic vessel regression. We also summarize current research on lymphatic vessel regression and an array of research tools and models that can be utilized to advance this field. Additionally, we discuss the roles of lymphatic vessel regression and dysfunction in select pathologies, highlighting how an improved understanding of lymphatic vessel regression may yield therapeutic insights for these disease states.

Development of Surgical and Visualization Procedures to Analyze Vasculatures by Mouse Tail Edema Model

Background

Because of the high frequency of chronic edema formation in the current “aged” society, analyses and detailed observation of post-surgical edema are getting more required. Post-surgical examination of the dynamic vasculature including L.V. (Lymphatic Vasculature) to monitor edema formation has not been efficiently performed. Hence, procedures for investigating such vasculature are essential. By inserting transparent sheet into the cutaneous layer of mouse tails as a novel surgery model (theTailEdema bySilicone sheet mediatedTransparency protocol; TEST), the novel procedures are introduced and analyzed by series of histological analyses including video-based L.V. observation and 3D histological reconstruction of vasculatures in mouse tails.

Results

The dynamic generation of post-surgical main and fine (neo) L.V. connective structure during the edematous recovery process was visualized by series of studies with a novel surgery model. Snapshot images taken from live binocular image recording for TEST samples suggested the presence of main and elongating fine (neo) L.V. structure. After the ligation of L.V., the enlargement of main L.V. was confirmed. In the case of light sheet fluorescence microscopy (LSFM) observation, such L.V. connections were also suggested by using transparent 3D samples. Finally, the generation of neo blood vessels particularly in the region adjacent to the silicone sheet and the operated boundary region was suggested in 3D reconstruction images. However, direct detection of elongating fine (neo) L.V. was not suitable for analysis by such LSFM and 3D reconstruction procedures. Thus, such methods utilizing fixed tissues are appropriate for general observation for the operated region including of L.V.

Conclusions

The current surgical procedures and analysis on the post-surgical status are the first case to observe vasculatures in vivo with a transparent sheet. Systematic analyses including the FITC-dextran mediated snap shot images observation suggest the elongation of fine (neo) lymphatic vasculature. Post-surgical analyses including LSFM and 3D histological structural reconstruction, are suitable to reveal the fixed structures of blood and lymphatic vessels formation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12575-021-00159-3.

Impact of a compression garment, on top of the usual care, in patients with breast cancer with early disturbance of the lymphatic transport: protocol of a randomised controlled trial

INTRODUCTION

Breast cancer-related lymphoedema (BCRL) is a common phenomenon. When lymphoedema is diagnosed late, options for treatment are diminished. Therefore, early diagnosis and treatment are very important to alter the potential deleterious evolution. Lymphofluoroscopy visualises the superficial lymphatic architecture in detail, giving the opportunity to detect a disturbance in the lymphatic transport (ie, dermal backflow) before the lymphoedema is clinically visible.The main objective is to investigate if there is an additional effect of a compression garment on top of the usual care (ie, information and exercises) in patients with early disturbance of the lymphatic transport after breast cancer treatment. Development of clinical lymphoedema and/or deterioration of the dermal backflow visualised by lymphofluoroscopy is investigated.

METHODOLOGY

All patients scheduled for breast cancer surgery with unilateral axillary lymph node dissection or sentinel node biopsy in the Multidisciplinary Breast Clinic of the University Hospitals Leuven are being considered. Patients are assessed before surgery and at 1, 3, 6, 9, 12, 18, 24 and 36 months postoperatively. At each visit, a clinical assessment is performed determining the volume difference between both arms and hands (through circumference measurements and water displacement), the water content, the extracellular fluid, the pitting status and the skinfold thickness. Quality of life questionnaires are filled in. At each visit, a lymphofluoroscopy is performed as well. When a disturbance of the lymphatic transport is seen on lymphofluoroscopy, without the presence of clinical lymphoedema, the patient is randomised in either a control group receiving usual care or a preventive treatment group receiving usual care and a compression garment (whether or not combined with a glove).

ETHICS AND DISSEMINATION

The trial is conducted in compliance with the principles of the Declaration of Helsinki (2008), the principles of Good Clinical Practice and in accordance with all applicable regulatory requirements. This protocol has been approved by the Ethical Committee of the University Hospitals Leuven. Results will be disseminated by peer-reviewed scientific journals and presentation at international congresses.

TRIAL REGISTRATION NUMBER

NCT03210311 CONCLUSION: The investigators hypothesise that development of clinical BCRL can be prevented and/or the dermal backflow can be stabilised or improved, if a preventive treatment with compression garment is started in the early phase of disturbance.

Effects of the Traditional Chinese Medical Prescription Linba Fang as a Treatment for Lymphedema

Lymphedema can lead to a series of complicated and irreversible chronic pathological changes, including lymphatic fluid retention, infiltration of inflammatory cells, lipid deposition, and fibrosis of the surrounding tissues. Typically, compression physiotherapy is recommended for early lymphedema. However, the chronic fluid compartments will lead to fat deposition, skin fibrosis, and hyperkeratosis. Few treatment methods are available for patients with lymphedema. Previous studies have attempted to apply diuretics, diosmin, and sodium β-aescinate to treatment for venous edema, but the curative effect was unsatisfactory. There is currently no established effective treatment for lymphedema. In this paper, we investigated the effects of the traditional Chinese medical prescription Linba Fang as a treatment for lymphedema using a mouse model. A lymphedema model was established in C57BL/6 mice through lymphatic ablation at the base of tails. Negative controls were administered with 0.5% sodium carboxymethyl cellulose solution by gavage twice daily, positive controls with aescuvenforte, and test mice with Linba Fang. Aescuvenforte and Linba Fang were dissolved in 0.5% sodium carboxymethyl cellulose solution to produce a homogeneous mixture. After treatment for 2-4 weeks, tail diameter and weight, inflammatory cytokine levels (IL-1, IL-6, and TNF-α), lipid deposition, and fibrosis were evaluated. The results showed that none of the mice died during the treatment with Linba Fang. The levels of tail swelling, inflammation, lipid deposition, and fibrosis in mice treated with Linba Fang were significantly decreased compared with negative and positive controls. Among mice treated with the same dose of Linba Fang, the levels of tail swelling, inflammation, lipid deposition, and fibrosis in mice treated for 4 weeks were significantly lower than those treated for 2 weeks. Among mice treated for the same duration of time, the levels of tail swelling, inflammation, lipid deposition, and fibrosis showed a decreasing tendency following increasing doses. Notably, the inflammation in tail tissues decreased to the similar level of normal group after treatment for 4 weeks using the high dose of Linba Fang. In conclusion, the traditional Chinese medical prescription Linba Fang could inhibit the pathological changes caused by lymphedema, including swelling, inflammation, lipid deposition, and fibrosis.

Lymphatic Valves and Lymph Flow in Cancer-Related Lymphedema

Lymphedema is a complex disease caused by the accumulation of fluid in the tissues resulting from a dysfunctional or damaged lymphatic vasculature. In developed countries, lymphedema most commonly occurs as a result of cancer treatment. Initially, impaired lymph flow causes edema, but over time this results in inflammation, fibrotic and fatty tissue deposition, limited mobility, and bacterial infections that can lead to sepsis. While chronically impaired lymph flow is generally believed to be the instigating factor, little is known about what pathophysiological changes occur in the lymphatic vessels to inhibit lymph flow. Lymphatic vessels not only regulate lymph flow through a variety of physiologic mechanisms, but also respond to lymph flow itself. One of the fascinating ways that lymphatic vessels respond to flow is by growing bicuspid valves that close to prevent the backward movement of lymph. However, lymphatic valves have not been investigated in cancer-related lymphedema patients, even though the mutations that cause congenital lymphedema regulate genes involved in valve development. Here, we review current knowledge of the regulation of lymphatic function and development by lymph flow, including newly identified genetic regulators of lymphatic valves, and provide evidence for lymphatic valve involvement in cancer-related lymphedema.

The results of the intensive phase of complete decongestive therapy and the determination of predictive factors for response to treatment in patients with breast cancer related-lymphedema

BACKGROUND

Lymphedema is a common complication of breast cancer or its treatment. The gold standard treatment for lymphedema is complete decongestive therapy. There are few studies about the predictive factors for the effectiveness of complete decongestive therapy.

AIM

To evaluate the results of the intensive phase of complete decongestive therapy, and to determine the predictive factors for the response to treatment in patients with breast cancer-related lymphedema.

METHODS AND RESULTS

Fifty-seven patients with breast cancer-related lymphedema (mean age: 56.2 ± 11.2 years) who underwent complete decongestive therapy between 2014 and 2016 were evaluated retrospectively. Extremity volume was calculated using circumferential measurements and the truncated cone formula technique. Response to treatment was evaluated using the percentage reduction of excess volume formula, which was obtained by calculating the extremity volume before and after treatment. The median percentage reduction of excess volume was 27.7% (IQR,13.6-50.3). The history of skin infection was related to lower percentage reduction of excess volume (P = 0.001). Although percentage reduction of excess volume was positively correlated with education level (r = 0.286, P = 0.031), percentage reduction of excess volume was negatively correlated with lymphedema duration (r = -0.361, P = 0.006), postoperative duration (r = -0.314, P = 0.018), percentage of excess volume (r = -0.398, P = 0.002), and number of complete decongestive therapy sessions (r = -0.436, P = 0.001). Univariate and multivariate analyses showed that the independent variables for percentage reduction of excess volume were percentage of excess volume (P = 0.009) and education level (P = 0.021).

CONCLUSION

Complete decongestive therapy is an effective method in patients with breast cancer related-lymphedema. The most important predictive factors for the efficacy of treatment were found as percentage of excess volume and education level. Patients with breast cancer should be followed up regularly and receive complete decongestive therapy in the early stage of lymphedema.

Adipose-Derived Stem Cells Promote Intussusceptive Lymphangiogenesis by Restricting Dermal Fibrosis in Irradiated Tissue of Mice

Currently, there is no definitive treatment for lymphatic disorders. Adipose-derived stem cells (ADSCs) have been reported to promote lymphatic regeneration in lymphedema models, but the mechanisms underlying the therapeutic effects remain unclear. Here, we tested the therapeutic effects of ADSC transplantation on lymphedema using a secondary lymphedema mouse model. The model was established in C57BL/6J mice by x-irradiation and surgical removal of the lymphatic system in situ. The number of lymphatic vessels with anti-lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) immunoreactivity increased significantly in mice subjected to transplantation of 7.5 × 10⁵ ADSCs. X-irradiation suppressed lymphatic vessel dilation, which ADSC transplantation could mitigate. Proliferative cell nuclear antigen staining showed increased lymphatic endothelial cell (LEC) and extracellular matrix proliferation. Picrosirius red staining revealed normal collagen fiber orientation in the dermal tissue after ADSC transplantation. These therapeutic effects were not related to vascular endothelial growth factor (VEGF)-C expression. Scanning electron microscopy revealed structures similar to the intraluminal pillar during intussusceptive angiogenesis on the inside of dilated lymphatic vessels. We predicted that intussusceptive lymphangiogenesis occurred in lymphedema. Our findings indicate that ADSC transplantation contributes to lymphedema reduction by promoting LEC proliferation, improving fibrosis and dilation capacity of lymphatic vessels, and increasing the number of lymphatic vessels via intussusceptive lymphangiogenesis.

Effects of mobilized peripheral blood stem cells on treatment of primary lower extremity lymphedema

OBJECTIVE

Lymphedema is a chronic debilitating disease characterized by the accumulation of fluid in the extremities as a result of lymphatic system impairment. Current treatments fail to restore the functionality and structural integrity of the lymphatic vessels lost in this condition. In this study, autologous mobilized peripheral blood stem cell transplantation was used and its potential efficacy and safety were evaluated in treating this condition.

METHODS

Ten patients with primary lymphedema in the lower extremity received granulocyte-colony stimulating factor subcutaneously for 4 days, to stimulate stem cell mobilization, after which 200 to 250 mL of blood was drawn from each patient and used to collect stem cells. Mobilized stem cells were counted by flow cytometry with International Society of Hematotherapy and Graft Engineering method. In two sessions, 3 weeks apart, these stem cells were injected subcutaneously in the affected limb at approximately 80 points, along the lymphatic vessels. Each patient was followed for 6 months, during which changes in the limb volume and circumference were measured. Lymphangiogenesis was evaluated by biopsy, the lymphoscintigraphic transport index was calculated using Lymphoscintigraphy, and quality of life was surveyed.

RESULTS

In this study, patients received on average 9.5 ± 6.8 × 10⁸ mononuclear cells (which divided into 2 × 10⁶ CD34⁺ cells for each session) in two sessions. The volume of the lower limbs decreased in 60% of patients. One patient showed a slight increase in the volume of lower limbs and three showed no change. The average limb volume was 4469.41 ± 1760.71 cm³, which on average differed from the average initial limb volume by 232.88 ± 392.53 cm³. Quality of life was reported as slightly increased in 60% of patients. The lymphoscintigraphic transport index suggested improvement in 60% of the patients. Likewise, tissue samples showed a 60% increase in lymphatic vessels.

CONCLUSIONS

Subcutaneous injection of autologous hematopoietic stem cells harvested from peripheral blood into patients with primary lower limb lymphedema is feasible, potentially effective, and without serious adverse effects. However, a larger scale study with more patients is needed to validate our results. Last, to increase the effectiveness of this treatment, the optimal dose of cells injected and the requirement for additional growth factors need further study.

Lymphatic Function and Dysfunction in the Context of Sex Differences

Endothelial cells are the building blocks of the blood vascular system and exhibit well-characterized sexually dimorphic phenotypes with regard to chromosomal and hormonal sex, imparting innate genetic and physiological differences between male and female vascular systems and cardiovascular disease. However, even though females are predominantly affected by disorders of lymphatic vascular function, we lack a comprehensive understanding of the effects of sex and sex hormones on lymphatic growth, function, and dysfunction. Here, we attempt to comprehensively evaluate the current understanding of sex as a biological variable influencing lymphatic biology. We first focus on elucidating innate and fundamental differences between the sexes in lymphatic function and development. Next, we delve into lymphatic disease and explore the potential underpinnings toward bias prevalence in the female population. Lastly, we incorporate more broadly the role of the lymphatic system in sex-biased diseases such as cancer, cardiovascular disease, reproductive disorders, and autoimmune diseases to explore whether and how sex differences may influence lymphatic function in the context of these pathologies.

Metabolism in Acute-On-Chronic Liver Failure: The Solution More than the Problem

Chronic inflammatory liver disease with an acute deterioration of liver function is named acute-on-chronic inflammation and could be regulated by the metabolic impairments related to the liver dysfunction. In this way, the experimental cholestasis model is excellent for studying metabolism in both types of inflammatory responses. Along the evolution of this model, the rats develop biliary fibrosis and an acute-on-chronic decompensation. The acute decompensation of the liver disease is associated with encephalopathy, ascites, acute renal failure, an acute phase response and a splanchnic increase of pro- and anti-inflammatory cytokines. This multiorgan inflammatory dysfunction is mainly associated with a splanchnic and systemic metabolic switch with dedifferentiation of the epithelial, endothelial and mesothelial splanchnic barriers. Furthermore, a splanchnic infiltration by mast cells occurs, which suggests that these cells could carry out a compensatory metabolic role, especially through the modulation of hepatic and extrahepatic mitochondrial-peroxisome crosstalk. For this reason, we propose the hypothesis that mastocytosis in the acute-on-chronic hepatic insufficiency could represent the development of a survival metabolic mechanisms that mitigates the noxious effect of the hepatic functional deficit. A better understanding the pathophysiological response of the mast cells in liver insufficiency and portal hypertension would help to find new pathways for decreasing the high morbidity and mortality rate of these patients.

Vegfc/d-dependent regulation of the lymphatic vasculature during cardiac regeneration is influenced by injury context

The lymphatic vasculature mediates essential physiological functions including fluid homeostasis, lipid and hormone transport, and immune cell trafficking. Recent studies have suggested that promoting lymphangiogenesis enhances cardiac repair following injury, but it is unknown whether lymphangiogenesis is required for cardiac regeneration. Here, we describe the anatomical distribution, regulation, and function of the cardiac lymphatic network in a highly regenerative zebrafish model system using transgenic reporter lines and loss-of-function approaches. We show that zebrafish lacking functional vegfc and vegfd signaling are devoid of a cardiac lymphatic network and display cardiac hypertrophy in the absence of injury, suggesting a role for these vessels in cardiac tissue homeostasis. Using two different cardiac injury models, we report a robust lymphangiogenic response following cryoinjury, but not following apical resection injury. Although the majority of mutants lacking functional vegfc and vegfd signaling were able to mount a full regenerative response even in the complete absence of a cardiac lymphatic vasculature, cardiac regeneration was severely impaired in a subset of mutants, which was associated with heightened pro-inflammatory cytokine signaling. These findings reveal a context-dependent requirement for the lymphatic vasculature during cardiac growth and regeneration.

Functional lymphatic reconstruction with the "Selected Lymph Node" technique guided by a SPECT-CT lymphoscintigraphy

BACKGROUND

A new technique named "Selected Lymph Node" ("SeLyN") was evaluated, aiming to identify the most functional groin lymph nodes (LNs) for an effective LN transplantation.

METHODS

Bilateral lower-limb SPECT-CT was performed in the upper-limb lymphedema patients, to select the most radioactive inguinal LN. Recorded data included demographics, stage, etiology of lymphedema, flap consistency in accordance to preoperative findings, flap size, number of LN, and harvesting time. Infection episodes per year and volume changes of the upper limbs were documented. Donor-site complications were recorded and lower-limb evaluation was performed through clinical examination, volume analysis, and lymphoscintigraphy.

RESULTS

A total of 41 patients underwent a "SeLyN" transfer technique. The mean flap size was 28.34 cm² containing a mean of 3.4 LNs. The mean time spent on flap harvest was 39 minutes. A mean 56.5% volume reduction (P < .001) and a mean 1.41 to 0.29 infection episodes per patient per year (P < .001) were recorded. Clinical evaluation and lymphography of the donor site advocated no major complications for a mean follow-up period of 42.5 months.

CONCLUSIONS

"SeLyN" is a safe and effective technique in selecting the most suitable LNs, minimizing the donor-site morbidity, and decreasing the overall operating time.

Local pharmacological induction of angiogenesis: Drugs for cells and cells as drugs

The past decades have seen significant advances in pro-angiogenic strategies based on delivery of molecules and cells for conditions such as coronary artery disease, critical limb ischemia and stroke. Currently, three major strategies are evolving. Firstly, various pharmacological agents (growth factors, interleukins, small molecules, DNA/RNA) are locally applied at the ischemic region. Secondly, preparations of living cells with considerable bandwidth of tissue origin, differentiation state and preconditioning are delivered locally, rarely systemically. Thirdly, based on the notion, that cellular effects can be attributed mostly to factors secreted in situ, the cellular secretome (conditioned media, exosomes) has come into the spotlight. We review these three strategies to achieve (neo)angiogenesis in ischemic tissue with focus on the angiogenic mechanisms they tackle, such as transcription cascades, specific signalling steps and cellular gases. We also include cancer-therapy relevant lymphangiogenesis, and shall seek to explain why there are often conflicting data between in vitro and in vivo. The lion's share of data encompassing all three approaches comes from experimental animal work and we shall highlight common technical obstacles in the delivery of therapeutic molecules, cells, and secretome. This plethora of preclinical data contrasts with a dearth of clinical studies. A lack of adequate delivery vehicles and standardised assessment of clinical outcomes might play a role here, as well as regulatory, IP, and manufacturing constraints of candidate compounds; in addition, completed clinical trials have yet to reveal a successful and efficacious strategy. As the biology of angiogenesis is understood well enough for clinical purposes, it will be a matter of time to achieve success for well-stratified patients, and most probably with a combination of compounds.

Prioritization of genes involved in endothelial cell apoptosis by their implication in lymphedema using an analysis of associative gene networks with ANDSystem

BACKGROUND

Currently, more than 150 million people worldwide suffer from lymphedema. It is a chronic progressive disease characterized by high-protein edema of various parts of the body due to defects in lymphatic drainage. Molecular-genetic mechanisms of the disease are still poorly understood. Beginning of a clinical manifestation of primary lymphedema in middle age and the development of secondary lymphedema after treatment of breast cancer can be genetically determined. Disruption of endothelial cell apoptosis can be considered as one of the factors contributing to the development of lymphedema. However, a study of the relationship between genes associated with lymphedema and genes involved in endothelial apoptosis, in the associative gene network was not previously conducted.

METHODS

In the current work, we used well-known methods (ToppGene and Endeavour), as well as methods previously developed by us, to prioritize genes involved in endothelial apoptosis and to find potential participants of molecular-genetic mechanisms of lymphedema among them. Original methods of prioritization took into account the overrepresented Gene Ontology biological processes, the centrality of vertices in the associative gene network, describing the interactions of endothelial apoptosis genes with genes associated with lymphedema, and the association of the analyzed genes with diseases that are comorbid to lymphedema.

RESULTS

An assessment of the quality of prioritization was performed using criteria, which involved an analysis of the enrichment of the top-most priority genes by genes, which are known to have simultaneous interactions with lymphedema and endothelial cell apoptosis, as well as by genes differentially expressed in murine model of lymphedema. In particular, among genes involved in endothelial apoptosis, KDR, TNF, TEK, BMPR2, SERPINE1, IL10, CD40LG, CCL2, FASLG and ABL1 had the highest priority. The identified priority genes can be considered as candidates for genotyping in the studies involving the search for associations with lymphedema.

CONCLUSIONS

Analysis of interactions of these genes in the associative gene network of lymphedema can improve understanding of mechanisms of interaction between endothelial apoptosis and lymphangiogenesis, and shed light on the role of disturbance of these processes in the development of edema, chronic inflammation and connective tissue transformation during the progression of the disease.

Potential lymphangiogenesis therapies: Learning from current antiangiogenesis therapies-A review

In recent years, lymphangiogenesis, the process of lymphatic vessel formation from existing lymph vessels, has been demonstrated to have a significant role in diverse pathologies, including cancer metastasis, organ graft rejection, and lymphedema. Our understanding of the mechanisms of lymphangiogenesis has advanced on the heels of studies demonstrating vascular endothelial growth factor C as a central pro-lymphangiogenic regulator and others identifying multiple lymphatic endothelial biomarkers. Despite these breakthroughs and a growing appreciation of the signaling events that govern the lymphangiogenic process, there are no FDA-approved drugs that target lymphangiogenesis. In this review, we reflect on the lessons available from the development of antiangiogenic therapies (26 FDA-approved drugs to date), review current lymphangiogenesis research including nanotechnology in therapeutic drug delivery and imaging, and discuss molecules in the lymphangiogenic pathway that are promising therapeutic targets.

Mechanotransduction in Blood and Lymphatic Vascular Development and Disease

The blood and lymphatic vasculatures are hierarchical networks of vessels, which constantly transport fluids and, therefore, are exposed to a variety of mechanical forces. Considering the role of mechanotransduction is key for fully understanding how these vascular systems develop, function, and how vascular pathologies evolve. During embryonic development, for example, initiation of blood flow is essential for early vascular remodeling, and increased interstitial fluid pressure as well as initiation of lymph flow is needed for proper development and maturation of the lymphatic vasculature. In this review, we introduce specific mechanical forces that affect both the blood and lymphatic vasculatures, including longitudinal and circumferential stretch, as well as shear stress. In addition, we provide an overview of the role of mechanotransduction during atherosclerosis and secondary lymphedema, which both trigger tissue fibrosis.

Fish scale-derived collagen patch promotes growth of blood and lymphatic vessels in vivo

In this study, Type I collagen was extracted from fish scales asa potential alternative source of collagen for tissue engineering applications. Since unmodified collagen typically has poor mechanical and degradation stability both in vitro and in vivo, additional methylation modification and 1,4-butanediol diglycidyl ether (BDE) crosslinking steps were used to improve the physicochemical properties of fish scale-derived collagen. Subsequently, in vivo studies using a murine model demonstrated the biocompatibility of the different fish scale-derived collagen patches. In general, favorable integration of the collagen patches to the surrounding tissues, with good infiltration of cells, blood vessels (BVs) and lymphatic vessels (LVs) were observed under growth factor-free conditions. Interestingly, significantly higher (p<0.05) number of LVs was found to be more abundant around collagen patches with methylation modification and BDE crosslinking. Overall, we have demonstrated the potential application of fish scale-derived collagen as a promising scaffolding material for various biomedical applications.

STATEMENT OF SIGNIFICANCE

Currently the most common sources of collagen are of bovine and porcine origins, although the industrial use of collagen obtained from non-mammalian species is growing in importance, particularly since they have a lower risk of disease transmission and are not subjected to any cultural or religious constraints. However, unmodified collagen typically has poor mechanical and degradation stability both in vitro and in vivo. Hence, in this study, Type I collagen was successfully extracted from fish scales and chemically modified and crosslinked. In vitro studies showed overall improvement in the physicochemical properties of the material, whilst in vivo implantation studies showed improvements in the growth of blood and lymphatic host vessels in the vicinity of the implants.

Construction of tissue-engineered lymphatic vessel using human adipose derived stem cells differentiated lymphatic endothelial like cells and decellularized arterial scaffold: A preliminary study

We have previously demonstrated that human adipose-derived stem cells (hADSCs) can be differentiated into lymphatic endothelial like cells. The purpose of this study was to investigate the feasibility of utilizing the induced lymphatic endothelial like cells and decellularized arterial scaffold to construct the tissue-engineered lymphatic vessel. The hADSCs were isolated from adipose tissue in healthy adults and were characterized the multilineage differentiation potential. Decellularized arterial scaffold was prepared using the Triton x-100 method. ADSCs were differentiated into lymphatic-like endothelial cells, and the induced cells were then seeded onto the decellularized arterial scaffold to engineer the lymphatic vessel. The histological analyses were performed to examine the endothelialized construct. The decellularized arterial scaffold was successfully obtained and was able to maintain its vessel morphology. The isolated ADSCs can be differentiated into osteocytes and adipocytes. After seeding onto the scaffold, the seeded cells attached and grew well on the decellularized arterial scaffold. Our preliminary results demonstrated that the induced lymphatic endothelial like cells combined with decellularized arterial scaffold could be utilized to successfully engineer the lymphatic vessel. Our findings may be helpful for the development of tissue-engineering of the lymphatic graft.

Lymph Vessel Thrombus Detection in Cervical Lymphedema: A Case Series

Although thrombosis in the terminal part of thoracic duct has been described in patients with head and neck cancer and upper vein thrombosis, normally medical imaging is not successful in depicting such lymphatic thrombosis. This case series is about three patients with acute onset of cervical lymphedema following minor trauma or exceptional physical strain. Using high-resolution ultrasound, it was possible to detect a thrombus formation in the terminal parts of the thoracic duct or the lymph duct. Within a few weeks all patients recovered without relapse for several years.

[What physiotherapeutic method for the treatment of post-mastectomy lymphedema is the most effective?]

We have undertaken the search for the publications of interest in the following databases: Scopus, Web of Science, MedLine, The Cochrane Library, CyberLeninka, and Russian science citation index. In addition, we evaluated the effectiveness of the physical agents and procedures having different mechanisms of action of the known factors responsible for the development of post-mastectomy lymphedema. Such agents and procedures include self-massage, manual lymphatic drainage, therapeutic physical exercises, compression bandaging, wearing elastic compression garments, Kinesio Tex taping, pneumatic compression, ultrasonic, electrostatic, extracorporeal shock wave therapy, electrical muscle stimulation, microcurrent and low-intensity laser therapy. These methods and products were used by the authors of selected publications either separately or in the combined modes taking into consideration the significant differences between effects of the application of individual techniques. The results of the treatment are presented for different time periods, either in absolute units (cm or ml) in the majority of the cases or in relative units (%) only in part of them without information concerning the statistical significance of the results obtained. There is thus far neither the universal classification of post-mastectomy lymphedema nor the generally accepted approaches to its diagnostics and treatment. Therefore, it is impossible to give an unambiguous answer as regards the effectiveness of one or another method for the diagnostics and treatment of this condition. The author of the present article observed 172 patients at the age of 56.8±9.7 years suffering from late grade I-IV lymphedema treated with the use of local low-intensity low-frequency electric and magnetic therapy in the combination with pneumatic compression applied during 15 days. The results of the treatment were evaluated using water and impedance plethysmography. Within 4 weeks after the onset of therapy, the volume of the upper limb decreased on the average for all stages of lymphedema by 37.7±9.3% under effect of pneumatic compression alone, by 49.5±10.7% under the influence of its combination with electrotherapy, by 59.9±5.4% under the action of the combination of pneumatic compression with magnetotherapy, and by 76.3±7.3% after the application of all the three techniques together (p<0.05). Electrical neurostimulation of the blood vessels and skeletal muscles proved especially effective for the treatment of I-II grade lymphedema while magnetic therapy was most efficient for the management of grade III-IV lymphedema. The proposed method of combined physiotherapy looks very encouraging for the treatment of late lymphedema but does not completely solve all problems pertaining to the management of this pathological condition.

Total saponins of panaxnotoginseng promotes lymphangiogenesis by activation VEGF-C expression of lymphatic endothelial cells

ETHNOPHARMACOLOGICAL RELEVANCE

Lymphatic system plays an important role in maintaining the fluid homeostasis and normal immune responses, anatomic or functional obstruction of which leads to lymphedema, and treatments for therapeutic lymphangiogenesis are efficiency for secondary lymphedema. Total saponins of panaxnotoginseng (PNS) are a mixture isolated from Panaxnotoginseng (Burkill) F.H.Chen, which has been used as traditional Chinese medicine in China for treatment of cardio- and cerebro-vascular diseases. The aim of this study was to determine the effect and mechanism of PNS on lymphangiogenesis.

METHODS

The Tg (fli1: egfp; gata1: dsred) transgenic zebrafish embryos were treated with different concentrations of PNS (10, 50, 100μM) for 48h with or without the 6h pretreatment of the 30μM Vascular endothelial growth factors receptor (VEGFR)-3 kinase inhibitor, followed with morphological observation and lympangiogenesis of thoracic duct assessment. The effect of PNS on cell viability, migration, tube formation and Vascular endothelial growth factors (VEGF)-C mRNA and protein expression of lymphatic endothelial cells (LECs) were determined. The role of phosphatidylinositol-3 (PI-3)-kinase (PI3K), extracellular signal-regulated kinase (ERK)1/2 pathways, c-Jun N-terminal kinase (JNK) and P38 mitogen activated protein kinases (MAPK) signaling in PNS-induced VEGF-C expression of LECs by using pharmacological agents to block each signal.

RESULTS

PNS promotes lymphangiogenesis of thoracic duct in zebrafish with or without VEGFR3 Kinase inhibitor pre-impairment. PNS promotes proliferation, migration and tube formation of LECs. The tube formation induced by PNS could be blocked by VEGFR3 Kinase inhibitor. PNS induce VEGF-C expression of LEC, which could be blocked by ERK1/2, PI3K and P38MAPK signaling inhibitors.

CONCLUSION

PNS activates lymphangiogenesis both in vivo and in vitro by up-regulating VEGF-C expression and activation of ERK1/2, PI3K and P38MAPK signaling. These findings provide a novel insight into the role of PNS in lymphangiogenesis and suggest that it might be an attractive and suitable therapeutic agent for treating secondary lymphedema or other lymphatic system impairment related disease.

Lymphatic Vascular Regeneration: The Next Step in Tissue Engineering

The lymphatic system plays a crucial role in interstitial fluid drainage, lipid absorption, and immunological defense. Lymphatic dysfunction results in lymphedema, fluid accumulation, and swelling of soft tissues, as well as a potentially impaired immune response. Lymphedema significantly reduces quality of life of patients on a physical, mental, social, and economic basis. Current therapeutic approaches in treatment of lymphatic disease are limited. Over the last decades, great progress has been made in the development of therapeutic strategies to enhance vascular regeneration. These solutions to treat vascular disease may also be applicable in the treatment of lymphatic diseases. Comparison of the organogenic process and biological organization of the vascular and lymphatic systems and studies in the regulatory mechanisms involved in lymphangiogenesis and angiogenesis show many common features. In this study, we address the similarities between both transport systems, and focus in depth on the biology of lymphatic development. Based on the current advances in vascular regeneration, we propose different strategies for lymphatic tissue engineering that may be used for treatment of primary and secondary lymphedema.

Microcirculation-on-a-Chip: A Microfluidic Platform for Assaying Blood- and Lymphatic-Vessel Permeability

We developed a microfluidic model of microcirculation containing both blood and lymphatic vessels for examining vascular permeability. The designed microfluidic device harbors upper and lower channels that are partly aligned and are separated by a porous membrane, and on this membrane, blood vascular endothelial cells (BECs) and lymphatic endothelial cells (LECs) were cocultured back-to-back. At cell-cell junctions of both BECs and LECs, claudin-5 and VE-cadherin were detected. The permeability coefficient measured here was lower than the value reported for isolated mammalian venules. Moreover, our results showed that the flow culture established in the device promoted the formation of endothelial cell-cell junctions, and that treatment with histamine, an inflammation-promoting substance, induced changes in the localization of tight and adherens junction-associated proteins and an increase in vascular permeability in the microdevice. These findings indicated that both BECs and LECs appeared to retain their functions in the microfluidic coculture platform. Using this microcirculation device, the vascular damage induced by habu snake venom was successfully assayed, and the assay time was reduced from 24 h to 30 min. This is the first report of a microcirculation model in which BECs and LECs were cocultured. Because the micromodel includes lymphatic vessels in addition to blood vessels, the model can be used to evaluate both vascular permeability and lymphatic return rate.

In vitro study on the safety of near infrared laser therapy in its potential application as postmastectomy lymphedema treatment

Clinical studies demonstrated the effectiveness of laser therapy in the management of postmastectomy lymphedema, a discomforting disease that can arise after surgery/radiotherapy and gets progressively worse and chronic. However, safety issues restrict the possibility to treat cancer patients with laser therapy, since the effects of laser radiation on cancer cell behavior are not completely known and the possibility of activating postmastectomy residual cancer cells must be considered. This paper reports the results of an in vitro study aimed to investigate the effect of a class IV, dual-wavelength (808 nm and 905 nm), NIR laser system on the behavior of two human breast adenocarcinoma cell lines (namely, MCF7 and MDA-MB361 cell lines), using human dermal fibroblasts as normal control. Cell viability, proliferation, apoptosis, cell cycle and ability to form colonies were analyzed in order to perform a cell-based safety testing of the laser treatment in view of its potential application in the management of postmastectomy lymphedema. The results showed that, limited to the laser source, treatment conditions and experimental models used, laser radiation did not significantly affect the behavior of human breast adenocarcinoma cells, including their clonogenic efficiency. Although these results do not show any significant laser-induced modification of cancer cell behavior, further studies are needed to assess the possibility of safely applying NIR laser therapy for the management of postmastectomy lymphedema.

Adjuvant taxanes and the development of breast cancer-related arm lymphoedema

BACKGROUND

Despite affecting approximately one-quarter of all patients undergoing axillary lymph node dissection, the pathophysiology of breast cancer-related lymphoedema (BCRL) remains poorly understood. More extensive locoregional treatment and higher body mass index have long been identified as major risk factors. This study aimed to identify risk factors for BCRL with a specific focus on the potential impact of chemotherapy on the risk of BCRL.

METHODS

This was a retrospective analysis of a cohort of consecutive patients with breast cancer treated at a major London regional teaching hospital between 1 January 2010 and 31 December 2012. All patients had node-positive disease and underwent axillary lymph node dissection. Data regarding tumour-, patient- and treatment-related characteristics were collected prospectively. The diagnosis of BCRL was based on both subjective and objective criteria. Multivariable Cox proportional hazards regression was used to assess the association between treatment and risk of BCRL.

RESULTS

Some 27.1 per cent of all patients (74 of 273) developed BCRL over the study period. Administration of taxanes showed a strong association with the development of BCRL, as 52 (33.5 per cent) of 155 patients who received taxanes developed BCRL. Multivariable Cox regression analysis demonstrated that patients who received taxanes were nearly three times more likely to develop BCRL than patients who had no chemotherapy (hazard ratio 2.82, 95 per cent c.i. 1.31 to 6.06). No such increase was observed when taxanes were administered in the neoadjuvant setting.

CONCLUSION

The present findings suggest that adjuvant taxanes play a key role in the development of BCRL after surgery. This may support the use of taxanes in a neoadjuvant rather than adjuvant setting.

Lymphedema and subclinical lymphostasis (microlymphedema) facilitate cutaneous infection, inflammatory dermatoses, and neoplasia: A locus minoris resistentiae

Whether primary or secondary, lymphedema is caused by failure to drain protein-rich interstitial fluid. Typically affecting a whole limb, it has become apparent that lymphedema can also affect localized regions of the skin, or it can be clinically silent but histologically evident, denoted by dilated lymphangiectases (latent lymphedema). Chronic lymph stasis has numerous consequences, including lipogenesis, fibrosis, inflammation, lymphangiogenesis, and immunosuppression. For example, lymphedema's disruption of immune cell trafficking leads to localized immune suppression, predisposing the area affected to chronic inflammation, infection (cellulitis and verrucosis), and malignancy (angiosarcoma and nonmelanoma skin cancer). The pathogenesis of lymphedema is reviewed and exemplified by describing how a combination of lymph stasis-promoting factors such as trauma, obesity, infection, and inflammatory disorders produces localized elephantiasis; furthermore, the finding of lymphangiectases is found to be common in numerous dermatologic disorders and argued to play a role in their pathogenesis. Lastly, it is discussed how antigen burden, which is controlled by lymphatic clearance, affects the immune response, resulting in immune tolerance, immunopathology, or normal adaptive immunity.

Apelin promotes lymphangiogenesis and lymph node metastasis

Whereas the role of the G-protein-coupled APJ receptor and its ligand, apelin, in angiogenesis has been well documented, the ability of the apelin/APJ system to induce lymphangiogenesis and lymphatic metastasis has been largely unexplored. To this end, we first show that APJ is expressed in lymphatic endothelial cells (LECs) and, moreover, that it responds to apelin by activating the apelinergic signaling cascade. We find that although apelin treatment does not influence the proliferation of LECs in vitro, it enhances their migration, protects them against UV irradiation-induced apoptosis, increases their spheroid numbers in 3D culture, stimulates their in vitro capillary-like tube formation and, furthermore, promotes the invasive growth of lymphatic microvessels in vivo in the matrigel plug assay. We also demonstrate that apelin overexpression in malignant cells is associated with accelerated in vivo tumor growth and with increased intratumoral lymphangiogenesis and lymph node metastasis. These results indicate that apelin induces lymphangiogenesis and, accordingly, plays an important role in lymphatic tumor progression. Our study does not only reveal apelin as a novel lymphangiogenic factor but might also open the door for the development of novel anticancer therapies targeting lymphangiogenesis.

Adolescent Onset of Localized Papillomatosis, Lymphedema, and Multiple Beta-Papillomavirus Infection: Epidermal Nevus, Segmental Lymphedema Praecox, or Verrucosis? A Case Report and Case Series of Epidermal Nevi

Herein, we report the case of a 12-year-old female who noted the recent onset of an oval, circumscribed, 10-cm papillomatous plaque affecting the thigh and vulva that showed histologic signs of lymphedema without evidence of secondary lymphedema. The sequencing of genes associated with a delayed onset of lymphedema or epidermal nevi (EN) - GATA2 and GJC2, and HRAS and KRAS, respectively - showed wild-type alleles. Polymerase chain reaction for human papillomavirus (HPV) DNA demonstrated infections with 15 HPV genotypes. Evidence of productive HPV infection, HPV capsid expression, and cytopathic changes was detected. At the 6-month follow-up, no evidence of recurrence was found after complete excision. The analysis of a consecutive series of 91 EN excision specimens revealed that 76% exhibited histologic evidence of lymphostasis. Notably, multiple acrochordon-like EN, which most closely resembled this case, showed similar signs of localized lymphedema. The late onset and evidence of lymphedema favors the diagnosis of congenital unisegmental lymphedema. However, the clinical findings and epidermal changes point to the diagnosis of EN. Moreover, localized verrucosis also accurately describes this patient's cutaneous findings. Based on the above evidence, we postulate that an abnormal development of lymphatics may play a primary role in the pathogenesis of some types of EN and facilitate productive HPV infection.

Tissue-engineered lymphatic graft for the treatment of lymphedema

BACKGROUND

Lymphedema is a chronic debilitating condition and curative treatment is yet to be found. Tissue engineering approach, which combines cellular components, scaffold, and molecular signals hold great potential in the treatment of secondary lymphedema with the advent of lymphatic graft to reconstruct damaged collecting lymphatic vessel. This review highlights the ideal characteristics of lymphatic graft, the limitation and challenges faced, and the approaches in developing tissue-engineered lymphatic graft.

METHODS

Literature on tissue engineering of lymphatic system and lymphatic tissue biology was reviewed.

RESULTS

The prime challenge in the design and manufacturing of this graft is producing endothelialized conduit with intraluminal valves. Suitable scaffold material is needed to ensure stability and functionality of the construct. Endothelialization of the construct can be enhanced via biofunctionalization and nanotopography, which mimics extracellular matrix. Nanocomposite polymers with improved performance over existing biomaterials are likely to benefit the development of lymphatic graft.

CONCLUSIONS

With the in-depth understanding of tissue engineering, nanotechnology, and improved knowledge on the biology of lymphatic regeneration, the aspiration to develop successful lymphatic graft is well achievable.

A Chinese pedigree of lymphoedema-distichiasis syndrome with a novel mutation in the FOXC2 gene

Lymphoedema-distichiasis syndrome (LDS) is a syndromic form of primary lymphoedema associated with double rows of eyelashes (distichiasis). Mutations in the FOXC2 gene were reported to be associated with this syndrome. In this study, we identified in a Chinese LDS pedigree a novel FOXC2 gene mutation, C.370C>T, leading to p.Leu124Phe. The novel mutation is not a common polymorphism, but is co-inherited with the disease.

Genetics of lymphatic anomalies

Lymphatic anomalies include a variety of developmental and/or functional defects affecting the lymphatic vessels: sporadic and familial forms of primary lymphedema, secondary lymphedema, chylothorax and chylous ascites, lymphatic malformations, and overgrowth syndromes with a lymphatic component. Germline mutations have been identified in at least 20 genes that encode proteins acting around VEGFR-3 signaling but also downstream of other tyrosine kinase receptors. These mutations exert their effects via the RAS/MAPK and the PI3K/AKT pathways and explain more than a quarter of the incidence of primary lymphedema, mostly of inherited forms. More common forms may also result from multigenic effects or post-zygotic mutations. Most of the corresponding murine knockouts are homozygous lethal, while heterozygotes are healthy, which suggests differences in human and murine physiology and the influence of other factors.