Lymphedema

Results from A Comparative Study to Evaluate the Treatment Effectiveness of a Non-Pneumatic Compression Device versus an Advanced Pneumatic Compression Device for Lower Extremity Lymphedema Swelling (TEAYS study)

OBJECTIVES

Advanced pneumatic compression devices (APCDs) have been shown to be effective in treatment of lower extremity lymphedema in the home setting. However, adherence to self-care has been poor, and APCD's require patients to remain immobile during treatment. We evaluated the safety and efficacy of a novel non-pneumatic compression device (NPCD) for treating lower extremity lymphedema vs and APCD.

METHODS

A randomized, crossover head-to-head study was performed at nine sites in 2023. Patients were randomized to either the NPCD or a commercially available APCD. Patients used the randomly assigned initial device for 28 days with a 4-week washout period before a comparable 28-day use of the second device.

RESULTS

A total of 71 patients (108 affected limbs) with lower extremity lymphedema were analyzed. Compared with the APCD, the NPCD was associated with a greater mean reduction in limb edema volume (a mean limb volume reduction of 369.9 (± 68.19) mL p<0.05 vs 83.1 (± 67.99 mL) p<0.05). Significant improvement in Quality of Life was achieved for NPCD and but not for APCD treatment (score improvement of 1.01 (± 0.23) (p<0.05) for NPCD vs 0.17 (± 0.18) (p>0.05) for APCD). Patients reported greater adherence (81% vs 56%, p<0.001) and satisfaction with the NPCD (78% vs 22%) compared to APCD. No device related adverse events were reported.

CONCLUSIONS

The novel NPCD is an effective treatment for reducing limb volume in patients with lower extremity lymphedema. The NPCD was more effective than an APCD and resulted in superior limb volume reduction, greater improved QoL, adherence, mobility, and patient satisfaction.

Breast cancer-related lymphedema: A critical review on recent progress

Lymphedema is a chronic and debilitating condition characterized by an abnormal buildup of protein-rich fluid in the interstitial tissue, leading to the development of edema and tissue structural alterations. Breast cancer-related lymphedema (BCRL) remains a significant healthcare burden because it can develop within days and up to 11-years after the surgery. Specifically, axillary lymph node dissection leads to 30-50 % upper limb lymphedema, which involves the accumulation of protein-rich fluid. In this article, we provide a comprehensive/critical overview of post-mastectomy lymphedema, focusing on key aspects as diagnosis, prevention, and treatment methods. Beginning with clinical condition, the article explores the pathophysiology and risk factors associated with post-mastectomy lymphedema. It further delves into various diagnostic modalities available, highlighting the importance of early detection for optimal management of BCRL. We also examine preventive strategies, emphasizing the role of patient education, lifestyle modifications, and proactive measures in reducing the risk of lymphedema development. In terms of treatment, the article covers a wide array of interventions ranging from conservative approaches like manual lymphatic drainage and compression therapy to surgical techniques such as lymph node transfer and lymphaticovenular anastomosis. Thus, through a comprehensive synthesis of current evidence and clinical practices updates, the review aims to guide healthcare professionals in delivering preventive and effective care while improving outcomes for individuals affected by post-mastectomy lymphedema.

Lymphatic endothelial cell-targeting lipid nanoparticles delivering VEGFC mRNA improve lymphatic function after injury

Dysfunction of the lymphatic system following injury, disease, or cancer treatment can lead to lymphedema, a debilitating condition with no cure. Advances in targeted therapy have shown promise for treating diseases where conventional therapies have been ineffective and lymphatic vessels have recently emerged as a new therapeutic target. Lipid nanoparticles (LNPs) have emerged as a promising strategy for tissue specific delivery of nucleic acids. Currently, there are no approaches to target LNPs to lymphatic endothelial cells, although it is well established that intradermal (ID) injection of nanoparticles will drain to lymphatics with remarkable efficiency. To design an LNP that would effectively deliver mRNA to LEC after ID delivery, we screened a library of 150 LNPs loaded with a reporter mRNA, for both self-assembly and delivery in vivo to lymphatic endothelial cells (LECs). We identified and validated several LNP formulations optimized for high LEC uptake when administered ID and compared their efficacy for delivery of functional mRNA with that of free mRNA and mRNA delivered with a commercially available MC3-based LNP (Onpattro™). The lead LEC-specific LNP was then loaded with VEGFC mRNA to test the therapeutic advantage of the LEC-specific LNP (namely, LNP7) for treating a mouse tail lymphatic injury model. A single dose of VEGFC mRNA delivered via LNP7 resulted in enhanced LEC proliferation at the site of injury, and an increase in lymphatic function up to 14-days post-surgery. Our results suggest a therapeutic potential of VEGFC mRNA lymphatic-specific targeted delivery in alleviating lymphatic dysfunction observed during lymphatic injury and could provide a promising approach for targeted, transient lymphangiogenic therapy.

Effects of Lymphaticovenous Anastomosis on Quality of Life, Body Image, and Spiritual Health in Lymphedema Patients: A Prospective Cohort Study

BACKGROUND

Lymphedema is a debilitating condition that significantly affects quality of life due to its chronic nature and visible symptoms. Lymphaticovenous anastomosis (LVA) has emerged as a promising surgical intervention, yet its effects on body image and spiritual health alongside physical symptoms have not been thoroughly examined. This study evaluates the efficacy of LVA in improving symptoms, quality of life (QOL), body image, and spiritual well-being in lymphedema patients.

METHODS

A prospective cohort study was conducted at Kaohsiung Chang Gung Memorial Hospital, Taiwan, involving 44 patients with lymphedema undergoing LVA surgery. Evaluations were made pre-surgery, one month post-surgery, and six months post-surgery using the 36-Item Short Form Health Survey (SF-36), Multidimensional Body-Self Relations Questionnaire-Appearance Scales (MBSRQ-AS), and a spiritual health scale. Statistical analysis was performed using one-way repeated measures ANOVA.

RESULTS

Significant improvements were observed in lymphedema symptoms and QOL measures at six months post-operation. SF-36 results showed enhanced scores in nearly all domains, particularly in physical functioning and role-physical. The appearance orientation scores from the MBSRQ-AS significantly increased, indicating improved perceptions in some dimensions of body image.

CONCLUSIONS

LVA surgery significantly enhances physical and psychological outcomes in patients with lymphedema, with marked improvements in symptoms, QOL, and body image perceptions. The findings suggest that while LVA is effective in addressing the physical and psychological aspects of lymphedema, it does not impact spiritual dimensions. This underscores the need for holistic approaches in the management of lymphedema to address all facets of patient well-being.

Impact of Lymphedema on Foot-Health-Related Quality of Life: A Case-Control Investigation

OBJECTIVE

To evaluate the foot-health-related quality of life in individuals with versus without lower-limb lymphedema.

METHODS

A case-control study was carried out in an academic clinic in Lisbon, Portugal. Eighty participants (40 controls and 40 with lymphedema) were included in the study. The researchers examined sociodemographic and clinical data and foot-health-related quality of life in both groups. In the group with lymphedema, lower-limb lymphedema was also characterized.

RESULTS

Individuals with lower-limb lymphedema had significantly lower scores on all dimensions of the Foot Health Status Questionnaire in comparison with the control group.

CONCLUSIONS

Individuals with lower-limb lymphedema appear to have a poorer foot-health-related quality of life than the general population.

Infliximab modifies CD74-mediated lymphatic abnormalities and adipose tissue alterations in creeping fat of Crohn's disease

BACKGROUND

Lymphatic abnormalities are essential for pathophysiologic changes of creeping fat (CrF) in Crohn's disease (CD). Anti-tumor necrosis factor (TNF) therapy has been proved to alleviate CrF lesions, however, whether it achieves these by remodeling lymphatics is unknown.

METHODS

CD74 expression was detected in CrF and uninvolved mesentery of CD patients. Lymphatic functions in vitro were evaluated and lymphatic endothelium barrier were checked by transendothelial electrical resistance (TEER) and FITC-Dextran permeability. Protein level of tight junction and signaling pathways were detected by western blotting.

RESULTS

CD74 was upregulated in LECs of CrF and positively correlated with TNF-α synthesis. This was suppressed by IFX administration. In vitro, TNF-α stimulated LECs to express CD74 through NF-κB signaling pathway, and this was rescued by IFX. CD74 downregulation suppressed the abilities of LECs in proliferation, migration and tube formation. Interaction of CD74-MIF impaired LECs' barrier via reducing tight junction proteins in an ERK1/2-dependent manner, which was reversed by CD74 downregulation. Consistently, the CD patients receiving IFX therapy displayed decreased lymphangiogenesis and improved mesenteric lymphatic endothelium barrier, companied with reduced adipocyte size and adipokine levels in CrF.

CONCLUSIONS

Anti-TNF therapy could modify pathological changes in CrF by alleviating CD74-mediated lymphatic abnormalities.

Time trend of breast cancer-related lymphedema according to body mass index

PURPOSE

To clarify how body mass index (BMI) affects the development and temporal trend of breast cancer-related lymphedema (BCRL).

METHODS

This is a prospective study in which patients with operable breast cancer were registered in a single institute between November 2009 and July 2010. The incidence of lymphedema at 1, 3, and 5 years after surgery was assessed according to BMI, and the trend of newly developed BCRL was examined. Obesity was defined as BMI ≥25 in accordance with the Japan Society for the Study of Obesity.

RESULTS

A total of 368 patients were included in this study. The multivariate analysis of the whole population showed that high BMI, axillary dissection, and radiotherapy remained as risk factors for BCRL. Patients with high BMI showed a significantly higher incidence of new lymphedema than those with low BMI at 1 year (p < 00.001) regardless of axillary procedures (39.1 % vs 16.3 % for axillary dissection; 15.6 % vs 1.5 % for sentinel lymph node biopsy) but not at 3 and 5 years. Once BCRL developed, patients with high BMI showed slow recovery and 50.0 % of the patients retained edema at 5 years while patients with low BMI showed rapid recovery and 26.7 % retained after 3 years (p = 0.04).

CONCLUSION

The preoperative BMI affected the incidence and temporal trend of BCRL regardless of axillary procedures or radiotherapy. Patients with high BMI should be given appropriate information about BCRL before surgery with careful follow-up for BCRL after treatment.

Edema of the upper extremity on the unaffected side in unilateral breast cancer patients

Breast cancer-related lymphedema (BCRL) occurs usually on the affected side, and its cause and pathophysiology are well known. However, the cause of edema of the upper extremity on the unaffected side is barely known. It is often considered to be chemotherapy-induced general edema, and clinical evaluation is rarely performed in these patients. This study aimed to present the clinical characteristics of unilateral breast cancer patients with edema of upper extremity on the unaffected side, and to emphasize the importance of early diagnosis and medical interventions. This study retrospectively analyzed the medical records of unilateral breast cancer patients complaining edema of upper extremity on the unaffected side, from January 2020 to May 2021. Lymphoscintigraphy was used to assist in confirming the diagnosis of lymphedema, and Doppler ultrasonography or 3D computed tomography angiography were performed to differentiate vascular problems. Fourteen patients were enrolled in the study. Seven, 3, and 4 patients had edema of both upper extremities, edema of the upper extremity on the unaffected side only, and edema of all extremities, respectively. None of the 4 patients with edema of all extremities showed abnormal findings on examination. In patients with edema in the upper extremity on the unaffected side alone, lymphatic flow dysfunction was seen in 2 patients, and deep vein thrombosis (DVT) was diagnosed in 1. In patients with edema of both upper extremities, lymphatic flow dysfunction was seen in 2 patients, and DVT was diagnosed in 3. One patient had DVT and accompanying lymphatic flow dysfunction. Lymphedema and DVT were diagnosed in a number of patients with edema of the upper extremity on the unaffected side, and lymphedema can occur without direct injury to the lymphatic flow system. Therefore, clinicians should not overlook the fact that diseases that require early diagnosis and treatment can occur in patients with edema of the unaffected upper extremity.

Effectiveness of lymphaticovenular anastomosis for adult-onset primary lower limb lymphedema: A retrospective study

BACKGROUND

Surgical treatments such as lymphaticovenular anastomosis (LVA) are widely used in addition to conservative treatment of secondary lymphedema. However, their indications and effectiveness for primary lymphedema are unclear. This study aims to objectively demonstrate the effectiveness of LVA for adult-onset primary lymphedema from various perspectives.

METHODS

We retrospectively examined patients with primary lower limb lymphedema who underwent LVA between January 2018 and December 2021 and were 21 or older. Treatment effects were evaluated using lymphoscintigraphy, questionnaires, body mass index, extracellular fluid ratio, and lymphedema index preoperatively and 6 months postoperatively. The LVA was performed under general anesthesia.

RESULTS

We evaluated 11 patients (11 lower limbs). Out of seven patients with complete obstruction preoperatively, all presented partial obstruction according to the Taiwan Lymphoscintigraphy Staging classification with a significant decrease in the score. Significant improvements were observed in clinical symptoms ("hardness") and in quality of life ("appearance" and "ease of wearing compression garments") assessments. A significant change was observed in the extracellular water ratio but not in lower extremity lymphedema index (LELindex).

CONCLUSION

LVA was suggested as one of the potential treatment options for patients with adult-onset primary lymphedema in whom lymphatic flow was confirmed by lymphoscintigraphy. In addition to clinical symptoms and physical examination, the evaluation of adult-onset primary lymphedema should include the patient's quality of life.

Vascularized Lymph Node Transfer Surgery for Successful Resolution of Long-Standing Lower Limb Lymphedema With Charles Excision: A Case Report

Lymphedema, a chronic condition characterized by abnormal swelling resulting from impaired lymphatic drainage, poses significant challenges in clinical management, especially when conventional therapies prove ineffective. This case report elucidates the successful resolution of long-standing lower limb lymphedema in a 35-year-old male through innovative surgical interventions. Despite enduring symptoms for 15 years and undergoing various treatments without improvement, the patient achieved remarkable relief following vascularized lymph node transfer surgery combined with Charles excision. This multidisciplinary approach aimed to restore lymphatic function and alleviate tissue bulk, addressing the condition's functional and cosmetic aspects. Preoperative evaluations, including imaging studies confirming grade IV lymphedema, guided surgical planning and contributed to the successful outcome. Postoperatively, despite wound dehiscence, prompt management facilitated satisfactory wound healing, underscoring the importance of meticulous postoperative care. This case underscores the significance of surgical intervention in managing refractory lymphedema and emphasizes the need for tailored treatment strategies to optimize patient outcomes. Further research and clinical experience are warranted to refine surgical techniques and identify optimal patient selection criteria, advancing the management of this challenging condition.

Elephantiasis Nostras Verrucosa in a Patient With Lymphedema Tarda

This case report presents a rare and complex clinical scenario of a 42-year-old male diagnosed with elephantiasis nostras verrucosa in the context of lymphedema tarda. The patient's seven-year history of insidious and progressively worsening swelling over the left lower limb, inguino-scrotal region, and left upper limb posed diagnostic challenges, leading to a multidisciplinary evaluation. Clinical examination, imaging studies, and laboratory investigations were integral in confirming the diagnosis. The manifestation of elephantiasis nostras verrucosa, characterized by extensive hyperkeratosis, added a unique dimension to the clinical presentation. A comprehensive treatment approach involving nutritional supplementation and pharmacological interventions was initiated to address the multifaceted aspects of lymphatic dysfunction. This case underscores the importance of a collaborative and holistic approach to managing complex lymphatic disorders, contributing valuable insights to the medical literature.

The relationship of kinesiophobia in patients with lymphedema: a case-control investigation

Introduction

Kinesiophobia and lymphedema appear to be related conditions, and it is important to understand this relationship, as many of the symptoms and comorbidities presented by individuals with lower limb lymphedema are prevented and treated through movement, thus constituting kinesiophobia as a barrier to intervention. The objective of this study is, therefore, to evaluate and analyze the kinesiophobic beliefs reported by individuals with and without lower limb lymphedema, regarding the agreement, severity and differences found, and to establish levels of kinesiophobia.

Methods

A case-control study with a total sample of 80 participants (40 with lower limb lymphedema and 40 without) was performed. Both groups (with and without lymphedema) were characterized anthropologically, sociodemographically, and clinically. In the case group, lymphedema was evaluated. Participants in both groups completed the Tampa Scale for Kinesiophobia - 13 items (TSK-13).

Results

Individuals with lower limb lymphedema had higher TSK-13 scores than their matched group without lymphedema. The items belonging to the activity avoidance subscale had the highest agreement and score in both groups. Differences between groups were mainly established for items belonging to the somatic focus subscale, showing that individuals with lower limb lymphedema have kinesiophobic beliefs related to the perceived severity of their lymphedema. The prevalence of kinesiophobia was increased in both groups, but the severity was mild.

Conclusions

Considering the apparent tendency of people with lower limb lymphedema to present kinesiophobia and movement-limiting beliefs regarding the condition, greater attention should be paid to its assessment, prevention and treatment from a multidisciplinary and multimodal perspective, which takes into account the multiplicity of factors inherent to kinesiophobia and lymphedema and thus reduce their impact on the management of lymphedema.

A dual-clock-driven model of lymphatic muscle cell pacemaking to emulate knock-out of Ano1 or IP3R

Lymphatic system defects are involved in a wide range of diseases, including obesity, cardiovascular disease, and neurological disorders, such as Alzheimer's disease. Fluid return through the lymphatic vascular system is primarily provided by contractions of muscle cells in the walls of lymphatic vessels, which are in turn driven by electrochemical oscillations that cause rhythmic action potentials and associated surges in intracellular calcium ion concentration. There is an incomplete understanding of the mechanisms involved in these repeated events, restricting the development of pharmacological treatments for dysfunction. Previously, we proposed a model where autonomous oscillations in the membrane potential (M-clock) drove passive oscillations in the calcium concentration (C-clock). In this paper, to model more accurately what is known about the underlying physiology, we extend this model to the case where the M-clock and the C-clock oscillators are both active but coupled together, thus both driving the action potentials. This extension results from modifications to the model's description of the IP3 receptor, a key C-clock mechanism. The synchronised dual-driving clock behaviour enables the model to match IP3 receptor knock-out data, thus resolving an issue with previous models. We also use phase-plane analysis to explain the mechanisms of coupling of the dual clocks. The model has the potential to help determine mechanisms and find targets for pharmacological treatment of some causes of lymphoedema.

Development of Pressure Sensors to Help Support Community Lymphedema Monitoring: A Scoping Review

Breast cancer-related lymphedema is a condition occurring after a partial or full mastectomy, where there is a buildup of interstitial fluid in the body, particularly in the upper limb. There is a lack of at-home sensors that can help monitor the progression of lymphedema. The purpose of this scoping review is to gather relevant information on sensors for remote lymphedema monitoring. A literature search of Medline, PubMed, Scopus, Web of Science, and BMC databases yielded 96 studies. A total of six studies were selected for data extraction. Data were extracted from each study and organized into tables for analysis. A total of six different devices were mentioned in the six studies included in the scoping review, divided into wearable and nonwearable sensors. Nonwearable sensors were more likely to be adaptable for remote sensing as they were further along in development and commercially available on the market. Nonwearable sensors are more developed than wearable sensors for the purpose of remote lymphedema monitoring. This review advocates further development and validation of sensors for lymphedema management, particularly for remote monitoring and health assessments.

The Function of T Cell Immunity in Lymphedema: A Comprehensive Review

Lymphedema is a debilitating disease characterized by extremity edema, fibroadipose deposition, impaired lymphangiogenesis, and dysfunctional lymphatics, often with lymphatic injury secondary to the treatment of malignancies. Emerging evidence has shown that immune dysfunction regulated by T cells plays a pivotal role in development of lymphedema. Specifically, Th1, Th2, Treg, and Th17 cells have been identified as critical regulators of pathological changes in lymphedema. In this review, our aim is to provide an overview of the current understanding of the roles of CD4+ T cells, including Th1, Th2, Treg, and Th17 subsets, in the progression of lymphedema and to discuss associated therapies targeting T cell inflammation for management of lymphedema.

Response of lymphatic endothelial cells to combined spatial and temporal variations in fluid flow

One-way valves within lymphatic vessels are required for the efficient drainage of lymphatic fluids. Fluid flow is proposed to be a key cue in regulating both the formation and maintenance of lymphatic valves. However, to our knowledge, no previous study has systematically examined the response of LECs to the complex combination of spatially and temporally varying fluid flows that occur at lymphatic valves in vivo. We built an in vitro microfluidic device that reproduces key aspects of the flow environment found at lymphatic valves. Using this device, we found that a combination of spatially and temporally varying wall shear stresses (WSSs) led to upregulated transcription of PROX1 and FOXC2. In addition, we observed that combined spatial and temporal variations in WSS-modulated Ca2+ signaling and led to increased cellular levels of NFATc1. These observations suggest that the physical cues generated by the flow environment present within lymphatic valves may act to activate key regulatory pathways that contribute to valve maintenance.

Development of predictive models for lymphedema by using blood tests and therapy data

Lymphedema is a disease that refers to tissue swelling caused by an accumulation of protein-rich fluid that is usually drained through the lymphatic system. Detection of lymphedema is often based on expensive diagnoses such as bioimpedance spectroscopy, shear wave elastography, computed tomography, etc. In current machine learning models for lymphedema prediction, reliance on observable symptoms reported by patients introduces the possibility of errors in patient-input data. Moreover, these symptoms are often absent during the initial stages of lymphedema, creating challenges in its early detection. Identifying lymphedema before these observable symptoms manifest would greatly benefit patients by potentially minimizing the discomfort caused by these symptoms. In this study, we propose to use new data, such as complete blood count, serum, and therapy data, to develop predictive models for lymphedema. This approach aims to compensate for the limitations of using only observable symptoms data. We collected data from 2137 patients, including 356 patients with lymphedema and 1781 patients without lymphedema, with the lymphedema status of each patient confirmed by clinicians. The data for each patient included: (1) a complete blood count (CBC) test, (2) a serum test, and (3) therapy information. We used various machine learning algorithms (i.e. random forest, gradient boosting, decision tree, logistic regression, and artificial neural network) to develop predictive models on the training dataset (i.e. 80% of the data) and evaluated the models on the external validation dataset (i.e. 20% of the data). After selecting the best predictive models, we created a web application to aid medical doctors and clinicians in the rapid screening of lymphedema patients. A dataset of 2137 patients was assembled from Seoul National University Bundang Hospital. Predictive models based on the random forest algorithm exhibited satisfactory performance (balanced accuracy = 87.0 ± 0.7%, sensitivity = 84.3 ± 0.6%, specificity = 89.1 ± 1.5%, precision = 97.4 ± 0.7%, F1 score = 90.4 ± 0.4%, and AUC = 0.931 ± 0.007). We developed a web application to facilitate the swift screening of lymphedema among medical practitioners: https://snubhtxt.shinyapps.io/SNUBH_Lymphedema . Our study introduces a novel tool for the early detection of lymphedema and establishes the foundation for future investigations into predicting different stages of the condition.

In Vivo Dynamic and Static Analysis of Lymphatic Dysfunction in Lymphedema Using Near-Infrared Fluorescence Indocyanine Green Lymphangiography

BACKGROUND

Near-infrared fluorescence indocyanine green lymphangiography, a primary modality for detecting lymphedema, which is a disease due to lymphatic obstruction, enables real-time observations of lymphatics and reveals not only the spatial distribution of drainage (static analysis) but also information on the lymphatic contraction (dynamic analysis).

METHODS

We have produced total lymphatic obstruction in the upper limbs of 18 Sprague-Dawley rats through the dissection of proximal (brachial and axillary) lymph nodes and 20-Gy radiation (dissection limbs). After the model formation for 1 week, 9 animal models were observed for 6 weeks using near-infrared fluorescence indocyanine green lymphangiography by injecting 6-μL ICG-BSA (indocyanine green-bovine serum albumin) solution of 20-μg/mL concentration. The drainage pattern and leakage of lymph fluid were evaluated and time-domain signals of lymphatic contraction were observed in the distal lymphatic vessels. The obtained signals were converted to frequency-domain spectrums using signal processing.

RESULTS

The results of both static and dynamic analyses proved to be effective in accurately identifying the extent of lymphatic disruption in the dissection limbs. The static analysis showed abnormal drainage patterns and increased leakage of lymph fluid to the periphery of the vessels compared with the control (normal) limbs. Meanwhile, the waveforms were changed and the contractile signal frequency increased by 58% in the dynamic analysis. Specifically, our findings revealed that regular lymphatic contractions, observed at a frequency range of 0.08 to 0.13 Hz in the control limbs, were absent in the dissection limbs. The contractile regularity was not fully restored for the follow-up period, indicating a persistent lymphatic obstruction.

CONCLUSIONS

The dynamic analysis could detect the abnormalities of lymphatic circulation by observing the characteristics of signals, and it provided additional evaluation indicators that cannot be provided by the static analysis. Our findings may be useful for the early detection of the circulation problem as a functional evaluation indicator of the lymphatic system.

Edema and lymphatic clearance: molecular mechanisms and ongoing challenges

Resolution of edema remains a significant clinical challenge. Conditions such as traumatic shock, sepsis, or diabetes often involve microvascular hyperpermeability, which leads to tissue and organ dysfunction. Lymphatic insufficiency due to genetic causes, surgical removal of lymph nodes, or infections, leads to varying degrees of tissue swelling that impair mobility and immune defenses. Treatment options are limited to management of edema as there are no specific therapeutics that have demonstrated significant success for ameliorating microvascular leakage or impaired lymphatic function. This review examines current knowledge about the physiological, cellular, and molecular mechanisms that control microvascular permeability and lymphatic clearance, the respective processes for interstitial fluid formation and removal. Clinical conditions featuring edema, along with potential future directions are discussed.

Non-Invasive Portable Technologies for Monitoring Breast Cancer Related Lymphedema to Facilitate Telehealth: A Scoping Review

Breast cancer related lymphedema (BCRL) is a common, debilitating condition that can affect up to one in five breast cancer surviving patients (BCSP). BCRL can significantly reduce the quality of life (QOL) of patients and poses a significant challenge to healthcare providers. Early detection and continuous monitoring of lymphedema is crucial for the development of client-centered treatment plans for post-cancer surgery patients. Therefore, this comprehensive scoping review aimed to investigate the current technology methods used for the remote monitoring of BCRL and their potential to facilitate telehealth in the treatment of lymphedema. Initially, five electronic databases were systematically searched and analyzed following the PRISMA flow diagram. Studies were included, specifically if they provided data on the effectiveness of the intervention and were designed for the remote monitoring of BCRL. A total of 25 included studies reported 18 technological solutions to remotely monitor BCRL with significant methodological variation. Additionally, the technologies were categorized by method of detection and wearability. The findings of this comprehensive scoping review indicate that state-of-the-art commercial technologies were found to be more appropriate for clinical use than home monitoring, with portable 3D imaging tools being popular (SD 53.40) and accurate (correlation 0.9, p 0.05) for evaluating lymphedema in both clinic and home settings with expert practitioners and therapists. However, wearable technologies showed the most future potential for accessible and clinical long-term lymphedema management with positive telehealth outcomes. In conclusion, the absence of a viable telehealth device highlights the need for urgent research to develop a wearable device that can effectively track BCRL and facilitate remote monitoring, ultimately improving the quality of life for patients following post-cancer treatment.

Biomechanical control of lymphatic vessel physiology and functions

The ever-growing research on lymphatic biology has clearly identified lymphatic vessels as key players that maintain human health through their functional roles in tissue fluid homeostasis, immunosurveillance, lipid metabolism and inflammation. It is therefore not surprising that the list of human diseases associated with lymphatic malfunctions has grown larger, including issues beyond lymphedema, a pathology traditionally associated with lymphatic drainage insufficiency. Thus, the discovery of factors and pathways that can promote optimal lymphatic functions may offer new therapeutic options. Accumulating evidence indicates that aside from biochemical factors, biomechanical signals also regulate lymphatic vessel expansion and functions postnatally. Here, we review how mechanical forces induced by fluid shear stress affect the behavior and functions of lymphatic vessels and the mechanisms lymphatic vessels employ to sense and transduce these mechanical cues into biological signals.

The emerging importance of lymphatics in health and disease: an NIH workshop report

The lymphatic system (LS) is composed of lymphoid organs and a network of vessels that transport interstitial fluid, antigens, lipids, cholesterol, immune cells, and other materials in the body. Abnormal development or malfunction of the LS has been shown to play a key role in the pathophysiology of many disease states. Thus, improved understanding of the anatomical and molecular characteristics of the LS may provide approaches for disease prevention or treatment. Recent advances harnessing single-cell technologies, clinical imaging, discovery of biomarkers, and computational tools have led to the development of strategies to study the LS. This Review summarizes the outcomes of the NIH workshop entitled "Yet to be Charted: Lymphatic System in Health and Disease," held in September 2022, with emphasis on major areas for advancement. International experts showcased the current state of knowledge regarding the LS and highlighted remaining challenges and opportunities to advance the field.

The emerging roles of long noncoding RNAs in lymphatic vascular development and disease

Recent advances in RNA sequencing technologies helped uncover what was once uncharted territory in the human genome-the complex and versatile world of long noncoding RNAs (lncRNAs). Previously thought of as merely transcriptional "noise", lncRNAs have now emerged as essential regulators of gene expression networks controlling development, homeostasis and disease progression. The regulatory functions of lncRNAs are broad and diverse, and the underlying molecular mechanisms are highly variable, acting at the transcriptional, post-transcriptional, translational, and post-translational levels. In recent years, evidence has accumulated to support the important role of lncRNAs in the development and functioning of the lymphatic vasculature and associated pathological processes such as tumor-induced lymphangiogenesis and cancer metastasis. In this review, we summarize the current knowledge on the role of lncRNAs in regulating the key genes and pathways involved in lymphatic vascular development and disease. Furthermore, we discuss the potential of lncRNAs as novel therapeutic targets and outline possible strategies for the development of lncRNA-based therapeutics to treat diseases of the lymphatic system.

Depressive symptoms and their severity in a sample with lymphedema: a case-control investigation

Objectives

Depression is a condition that can be associated with other illnesses, especially chronic illnesses. Lower limb lymphedema is a chronic, disabling condition that can affect the quality of life and be related to psychological and psychosocial factors that interfere with people's lives. This study aims to characterize and analyze the depressive symptoms and their severity reported by people with lower limb lymphedema and compare them with a matched group without lymphedema.

Methods

A case-control study was carried out (n = 80) with participants divided into a case group (40 people with lower limb lymphedema) and a control group (40 people without lower limb lymphedema). Both groups were anthropometrically, sociodemographically, and clinically characterized. In the case group, a characterization of lymphedema was performed. Participants completed the Beck Depression Inventory-II.

Results

Individuals with lower limb lymphedema have higher BDI-II scores than the matched group without lymphedema. Somatic depressive symptoms were, in general, the most reported and the ones with the highest scores. The depressive symptoms most reported by the case group were tiredness or fatigue, loss of energy, and changes in sleeping. Tiredness or fatigue, loss of energy, and loss of interest in sex were the most severe depressive symptoms reported by individuals with lower limb lymphedema.

Conclusion

Considering the apparent tendency to depression, greater attention should be given to the mental health of people with lower limb lymphedema.

Differences in Transient Fluid Retention and Lymphedema With Breast Cancer Treatment for Lymphatic Microsurgery

BACKGROUND

Breast cancer-related lymphedema (BCRL) is a common complication. Repeated taxane-based chemotherapy has been shown to induce endothelial inflammation, leading to fluid retention. Patients with transient fluid retention only have upper limb edema without lymphatic dysfunction. Therefore, indocyanine green lymphography revealed linear findings, and lymphatic microsurgery is not required. This study aimed to investigate the difference between BCRL and fluid retention and present the indication for lymphatic microsurgery for these patients.

METHODS

The study population was divided into BCRL and fluid retention groups. Age, body mass index, laterality, surgery type (lymph node, breast, or no surgery), disease stage, regional lymph node irradiation, hormone therapy, chemotherapy type (taxane- or non-taxane-based group), and treatment with trastuzumab were compared.

RESULTS

The BCRL and fluid retention groups consisted of 168 and 73 patients, respectively. The BCRL group had significantly higher rates of axillary lymph node dissection (96.4%) and lymph node irradiation (51.8%) than the fluid retention group (53.4% and 24.7%, respectively; P < 0.001 for both). The fluid retention group had a significantly higher rate of taxane-based chemotherapy (100%) than the BCRL group (92.9%; P = 0.02). No significant differences in other characteristics, including treatments with hormone and trastuzumab, were observed.

CONCLUSIONS

Lymphatic microsurgery should be performed after confirming the diagnosis by indocyanine green lymphography, particularly for patients with fluid retention induced by taxane-based chemotherapy. Because the generalized swelling induced by taxane-based chemotherapy is resolved 6 months after chemotherapy, we should wait at least 6 months to perform lymphatic microsurgery.

Coping Mechanisms for Lymphedema: An Analysis of Patient Experiences

Background and objective Lymphedema is a condition caused by impaired lymphatic function. Acquired lymphedema is often due to neoplasia, infection, trauma, or radiation damage. Most patients rely on advice from fellow patients and personal research to manage their symptoms. We believe coping mechanisms for lymphedema can be more streamlined and made easily accessible if the most common effective strategies are determined and collected in a single repository for reference. To that end, we aimed to assess the experiences of lymphedema patients and the coping mechanisms they employed. Methods Feedback from lymphedema patients was obtained using a 19-item questionnaire-based survey distributed to multiple online lymphedema support groups. It focused on the type of lymphedema and its effect on the respondents and sought data to characterize coping mechanisms that individuals with lymphedema use and their effectiveness. Results The respondents (n=400) had a median age of 55 years (range: 18-83 years). The overall mean BMI was 35.8 kg/m2, with respondents with lower extremity (LE) lymphedema having a greater mean BMI (38.4 vs. 31.0, p<0.05). Most of the respondents were female (n=382, 95.5%). LE lymphedema was more common (n=280, 70%) than the upper extremity (UE) variant (n=120, 30%). Within the LE group, 99 were unilateral (35.4%) and 181 were bilateral (64.6%). Moderate restriction was the most reported level with 44% in the unilateral group and 64% in the bilateral group. Stretching, low-impact exercise, manual lymphatic drainage (MLD), and compression bandages were the most commonly used coping methods and most of the respondents rated them as somewhat effective. Of note, 30% of respondents in either group rated increased water intake as either slightly, moderately, or very helpful; 25% of respondents also rated decreased alcohol intake as very helpful. The use of a therapist and family and doctor support was rated as extremely helpful. Within the UE group, 105 were unilateral (87.5%) and 15 were bilateral (12.5%). The most common cause of UE lymphedema was breast cancer-related (98/120, 81.7%) followed by melanoma treatment. Mild restriction was the most reported level (n=48, 45.7%). The UE group had similar results as the LE group in terms of coping mechanisms, dietary changes, and psychosocial support. Conclusion Based on the experiences of the lymphedema patients surveyed, the management of the condition is multifactorial and hence not compatible with a one-size-fits-all strategy. LE lymphedema was more common than the UE variant; but both groups reported engaging in stretching, low-impact exercise, manual lymphatic drainage, and compression bandages with similar rates of satisfaction reported in both groups. Dietary changes were not commonly employed. Therapy, doctor, and family support were the most commonly used support mechanisms, with high satisfaction among both groups. The overall coping mechanisms and their ratings in terms of efficacy between UE and LE groups were similar although the impact of quality of life was greater for bilateral conditions. We believe our findings represent the first steps to providing information potentially useful to aid future and current lymphedema patients in finding the coping methods that work best for them.

Chronic Venous Insufficiency With Emphasis on the Geriatric Population

The underpinning of Chronic Venous Insufficiency (CVI) is valvular dysfunction, which manifests on a spectrum depending on the severity of insufficiency and duration of the disease. The mainstay of treatment relies on compression therapy of a proper type and intensity. In older adults, special consideration must be taken during the patient encounter to account for age-related factors. This review discusses the clinical presentation, diagnosis, and mimicking of CVI, focusing mainly on older adults. The epidemiology, risk factors, disease burden, and grave complications -- such as thrombosis and ulceration, are reviewed. The physiological impacts of CVI are described, providing the background for treatment strategies, including non-invasive, medical, and surgical therapies. The findings show advanced age to be an important risk factor contributing to CVI and that other age-related factors add to the risk of severe complications. Clinical assessments combined with objective measurements that assess localized skin water using tissue dielectric constant values or whole limb assessments may aid in the differential diagnosis. Furthermore, understanding the mechanism of action of compression therapy, the mainstay of CVI treatment, and its physiological impacts, allows for its informed use in geriatric patients with increased risks of potential compression-related side effects.

Therapeutic Lymphangiogenesis Is a Promising Strategy for Secondary Lymphedema

Secondary lymphedema is caused by lymphatic insufficiency (lymphatic drainage failure) following lymph node dissection during the surgical treatment or radiation therapy of breast or pelvic cancer. The clinical problems associated with lymphedema are reduced quality of life in terms of appearance and function, as well as the development of skin ulcers, recurrent pain, and infection. Currently, countermeasures against lymphedema are mainly physical therapy such as lymphatic massage, elastic stockings, and skin care, and there is no effective and fundamental treatment with a highly recommended grade. Therefore, there is a need for the development of a fundamental novel treatment for intractable lymphedema. Therapeutic lymphangiogenesis, which has been attracting attention in recent years, is a treatment concept that reconstructs the fragmented lymphatic network to recover lymphatic vessel function and is revolutionary to be a fundamental cure. This review focuses on the translational research of therapeutic lymphangiogenesis for lymphedema and outlines the current status and prospects in the development of therapeutic applications.

Impact of Goreisan components on rat mesenteric collecting lymphatic vessel pumping

BACKGROUND

Goreisan is a traditional herbal formulation with diuretic properties tested as a clinical therapeutic to alleviate lymphedema in Japan. The present study aimed to determine how Goreisan and its five different components affect lymphatic pump function.

METHODS

Mesenteric collecting lymphatics were isolated from anesthetized Sprague-Dawley rats and mounted on resistance-matched glass micropipettes in a 37°C physiological salt solution bath for studies. Diameter was continuously measured to obtain the following lymphatic pump parameters: contraction frequency (CF), end diastolic diameter (EDD), and end systolic diameter (ESD), contraction amplitude (AMP), ejection fraction (EF), and fractional pump flow (FPF). Goreisan and each of its components (Cinnamomi Cortex, Atractylodis Rhizoma, Alismatis Rhizoma, Polyporus, and Poria) were applied to the bath at concentrations of 1-30 μg/mL.

RESULTS

The results show that while Goreisan causes no significant changes to lymphatic pumping, Alismatis Rhizoma and Polyporus each significantly reduce CF and FPF. In addition, rats that received oral administration of Goreisan and Alismatis Rhizoma for 1 week had elevated expression of VEGFR-3 in their mesenteric collecting lymphatics.

CONCLUSIONS

Collectively, the results suggest that some components of Goreisan have a direct, rapid impact on lymphatic pumping. These findings provide new insights but also raise new questions about the therapeutic potential of Goreisan in patients with secondary lymphedema.

Lentiviral overexpression of VEGFC in transplanted MSCs leads to resolution of swelling in a mouse tail lymphedema model

BACKGROUND

Dysfunction of the lymphatic system following injury, disease, or cancer treatment can lead to lymphedema, a debilitating condition with no cure. Despite the various physical therapy and surgical options available, most treatments are palliative and fail to address the underlying lymphatic vascular insufficiency driving lymphedema progression. Stem cell therapy provides a promising alternative in the treatment of various chronic diseases with a wide range of therapeutic effects that reduce inflammation, fibrosis, and oxidative stress, while promoting lymphatic vessel (LV) regeneration. Specifically, stem cell transplantation is suggested to promote LV restoration, rebuild lymphatic circulation, and thus potentially be utilized towards an effective lymphedema treatment. In addition to stem cells, studies have proposed the administration of vascular endothelial growth factor C (VEGFC) to promote lymphangiogenesis and decrease swelling in lymphedema.

AIMS

Here, we seek to combine the benefits of stem cell therapy, which provides a cellular therapeutic approach that can respond to the tissue environment, and VEGFC administration to restore lymphatic drainage.

MATERIALS & METHODS

Specifically, we engineered mesenchymal stem cells (MSCs) to overexpress VEGFC using a lentiviral vector (hVEGFC MSC) and investigated their therapeutic efficacy in improving LV function and tissue swelling using near infrared (NIR) imaging, and lymphatic regeneration in a single LV ligation mouse tail lymphedema model.

RESULTS

First, we showed that overexpression of VEGFC using lentiviral transduction led to an increase in VEGFC protein synthesis in vitro. Then, we demonstrated hVEGFC MSC administration post-injury significantly increased the lymphatic contraction frequency 14-, 21-, and 28-days post-surgery compared to the control animals (MSC administration) in vivo, while also reducing tail swelling 28-days post-surgery compared to controls.

CONCLUSION

Our results suggest a therapeutic potential of hVEGFC MSC in alleviating the lymphatic dysfunction observed during lymphedema progression after secondary injury and could provide a promising approach to enhancing autologous cell therapy for treating lymphedema.

The Vicious Circle of Stasis, Inflammation, and Fibrosis in Lymphedema

SUMMARY

Lymphedema is a progressive disease of the lymphatic system arising from impaired lymphatic drainage, accumulation of interstitial fluid, and fibroadipose deposition. Secondary lymphedema resulting from cancer treatment is the most common form of the disease in developed countries, affecting 15% to 40% of patients with breast cancer after lymph node dissection. Despite recent advances in microsurgery, outcomes remain variable and, in some cases, inadequate. Thus, development of novel treatment strategies is an important goal. Research over the past decade suggests that lymphatic injury initiates a chronic inflammatory response that regulates the pathophysiology of lymphedema. T-cell inflammation plays a key role in this response. In this review, the authors highlight the cellular and molecular mechanisms of lymphedema and discuss promising preclinical therapies.

Role of Subcutaneous Adipose Tissues in the Pathophysiology of Secondary Lymphedema

Background: Secondary lymphedema (LE) occurs due to the disruption of lymphatic circulation. Lymphatic fluid accumulation in subcutaneous tissues induces adipocyte proliferation. Obesity is an important risk factor for the occurrence and deterioration of LE. Although the relationship between LE and subcutaneous adipose tissue increase has been reported clinically, their pathophysiological relationship remains unknown. Thus, we aimed to verify whether subcutaneous adipose tissue increase is involved in the pathophysiology of secondary LE. Methods and Results: The hindlimb model of secondary LE was created using male Sprague-Dawley rats (control and LE groups; n = 5 each). Skin samples were obtained on postoperative day 168. Histological examination and quantitative real-time polymerase chain reaction analysis of inflammatory adipokines, tumor necrosis factor-alpha (Tnf-α), C-C chemokine ligand 2 (Ccl2), and interleukin-6 (Il-6) were performed. Limb volume and subcutaneous adipose tissues significantly increased in the LE group compared with those in the control. Macrophages aggregated in the augmented adipose tissues, around the adipocytes, and formed crown-like structures (CLSs). The number of CLSs significantly increased in the LE group. These macrophages expressed transforming growth factor-beta 1 (TGF-β1). Inflammatory adipokine secretion was not observed. Although Il-6 expression increased in the LE group, IL-6 was expressed in subcutaneous myofibroblasts but not in subcutaneous adipocytes. Conclusion: As TGF-β1 derived from subcutaneous myofibroblasts is involved in skin fibrosis during LE, TGF-β1 derived from adipose tissues may also play a similar role. Drug treatment for subcutaneous adipose tissue reduction may improve the skin condition in secondary LE and may be a new therapeutic strategy.

Cancer Rehabilitation Fact Sheet in Korea

Cancer rehabilitation aims to enable patients to maximize their physical, social, psychological, and vocational functions within the limits that arise during the course of the disease and its treatment. According to recent domestic studies, most patients report one or more physical problems during or after cancer treatment. This review presents the latest updates on cancer-related rehabilitation issues. Cancer rehabilitation in Korea still faces various barriers, including a lack of awareness, problems with the healthcare delivery system, and high costs, and recognizing the need for rehabilitation during cancer treatment varies among patients and even physicians. Hence, an appropriate cooperative referral system for cancer rehabilitation requires improvement. We herein review the current status of and barriers to cancer rehabilitation in South Korea to resolve the issues of domestic cancer rehabilitation.

Effects of Lymphovenous Anastomosis Surgery Using Ultrasonography in Lymphedema From a Pressure Perspective

Objective

To analyze the effects of lymphovenous anastomosis (LVA) surgery after 1 year using the elastic index (EI) and volume.

Methods

This study was a retrospective study of 41 patients, with lymphedema, who underwent LVA surgery between July 2018 and June 2020. Limb circumference, used to determine the volume of the limb with lymphedema, and EI, which reflects tissue stiffness and measured using ultrasonography were measured for each patient before and 1 year after LVA surgery. To examine the effect of LVA, differences in the preoperative and 1-year postoperative volumes and EIs were analyzed using the Wilcoxon signed-rank test.

Results

The mean volume and EI of the dominant site in upper-extremity lymphedema were 2,309.4 cm³ and 1.4, respectively, preoperatively and 2,237.1 cm³ and 0.9, respectively, at 1 year postoperatively. The mean volume and EI difference of the dominant site 1 year after surgery was −16.6 cm³ (p=0.22) and −0.5 (p<0.001). The mean volume and EI of dominant site in lower-extremity lymphedema were 6,137.0 cm³ and 1.2, respectively, preoperatively, and 5,832.6 cm³ and 1.1, respectively, at 1 year postoperatively. The mean volume and EI difference of the dominant site 1 year postoperatively were −320.9 cm³ (p=0.04) and −0.2 (p=0.09), respectively.

Conclusion

LVA surgery is more effective in reducing pressure than in reducing volume, which may be helpful in preventing the progression of lymphedema.

Enhancement of Lymphangiogenesis by Human Mesenchymal Stem Cell Sheet

Preparation of human mesenchymal stem cell (hMSC) suspension for lymphedema treatment relies on conventional enzymatic digestion methods, which severely disrupts cell-cell and cell-extracellular matrix (ECM) connections, and drastically impairs cell retention and engraftment after transplantation. The objective of the present study is to evaluate the ability of hMSC-secreted ECM to augment lymphangiogenesis by using an in vitro coculturing model of hMSC sheets with lymphatic endothelial cells (LECs) and an in vivo mouse tail lymphedema model. Results demonstrate that the hMSC-secreted ECM augments the formation of lymphatic capillary-like structure by a factor of 1.2-3.6 relative to the hMSC control group, by serving as a prolymphangiogenic growth factor reservoir and facilitating cell regenerative activities. hMSC-derived ECM enhances MMP-2 mediated matrix remodeling, increases the synthesis of collagen IV and laminin, and promotes lymphatic microvessel-like structure formation. The injection of rat MSC sheet fragments into a mouse tail lymphedema model confirms the benefits of the hMSC-derived ECM by stimulating lymphangiogenesis and wound closure.

Vascularized Lymph Node Transfer Improved Outcomes of Elderly Patients with Secondary Upper Extremity Lymphedema

BACKGROUND

Secondary lymphedema is a debilitating morbidity. This study investigated the outcomes of vascularized lymph node transfer (VLNT) in elderly patients with secondary upper extremity lymphedema.

METHODS

Between 2008 and 2018, elderly (≥65 years) patients with secondary upper extremity lymphedema who underwent VLNT were retrospectively reviewed. Cheng's Lymphedema Grading, Taiwan Lymphoscintigraphy Staging, and indocyanine green lymphography were used to select the procedures. Outcome measurements included complications, circumferential difference, episodes of cellulitis, and the Lymphedema-Specific Quality of Life questionnaire (LYMQoL).

RESULTS

Eleven patients with a mean age of 70.2 ± 5.3 years (range 65-80 years) who underwent VLNT survived and no major complications were encountered. At a mean follow-up of 6.5 ± 3.6 years (range 2-13 years), the mean limb circumferential difference was significantly improved from 25.6 ± 11.5% to 8.3 ± 4.2% (p = 0.016), and the mean episode of cellulitis was statistically reduced from 2.4 ± 1.3 to 0.4 ± 0.9 times/year (p = 0.007). At a follow-up of 24 months, four domains of Function (from 30.6 ± 2.8 to 14.5 ± 2.5), Appearance (from 18.2 ± 1.9 to 8.5 ± 2.1), Symptoms (from 30.4 ± 5.9 to 10.9 ± 1.0) and Mood (from 29.2 ± 4.4 to 10.7 ± 1.0), as well as overall LYMQoL score (from 3.9 ± 1.1 to 7.4 ± 0.5), showed statistical improvement (all p < 0.05).

CONCLUSIONS

VLNT for secondary upper extremity lymphedema in elderly patients significantly decreased the limb circumferential difference and frequency of cellulitis and improved quality of life without using compression garments postoperatively.

Current Mechanistic Understandings of Lymphedema and Lipedema: Tales of Fluid, Fat, and Fibrosis

Lymphedema and lipedema are complex diseases. While the external presentation of swollen legs in lower-extremity lymphedema and lipedema appear similar, current mechanistic understandings of these diseases indicate unique aspects of their underlying pathophysiology. They share certain clinical features, such as fluid (edema), fat (adipose expansion), and fibrosis (extracellular matrix remodeling). Yet, these diverge on their time course and known molecular regulators of pathophysiology and genetics. This divergence likely indicates a unique route leading to interstitial fluid accumulation and subsequent inflammation in lymphedema versus lipedema. Identifying disease mechanisms that are causal and which are merely indicative of the condition is far more explored in lymphedema than in lipedema. In primary lymphedema, discoveries of genetic mutations link molecular markers to mechanisms of lymphatic disease. Much work remains in this area towards better risk assessment of secondary lymphedema and the hopeful discovery of validated genetic diagnostics for lipedema. The purpose of this review is to expose the distinct and shared (i) clinical criteria and symptomatology, (ii) molecular regulators and pathophysiology, and (iii) genetic markers of lymphedema and lipedema to help inform future research in this field.

Targeting Lymphatics for Nanoparticle Drug Delivery

The lymphatics transport material from peripheral tissues to lymph nodes, where immune responses are formed, before being transported into systemic circulation. With key roles in transport and fluid homeostasis, lymphatic dysregulation is linked to diseases, including lymphedema. Fluid within the interstitium passes into initial lymphatic vessels where a valve system prevents fluid backflow. Additionally, lymphatic endothelial cells produce key chemokines, such as CCL21, that direct the migration of dendritic cells and lymphocytes. As a result, lymphatics are an attractive delivery route for transporting immune modulatory treatments to lymph nodes where immunotherapies are potentiated in addition to being an alternative method of reaching systemic circulation. In this review, we discuss the physiology of lymphatic vessels and mechanisms used in the transport of materials from peripheral tissues to lymph nodes. We then summarize nanomaterial-based strategies to take advantage of lymphatic transport functions for delivering therapeutics to lymph nodes or systemic circulation. We also describe opportunities for targeting lymphatic endothelial cells to modulate transport and immune functions.

Reactive Oxygen Species in Regulating Lymphangiogenesis and Lymphatic Function

The lymphatic system is pivotal for immunosurveillance and the maintenance of tissue homeostasis. Lymphangiogenesis, the formation of new lymphatic vessels from pre-existing vessels, has both physiological and pathological roles. Recent advances in the molecular mechanisms regulating lymphangiogenesis have opened a new area of research on reparative lymphangiogenesis for the treatment of various pathological disorders comprising neurological disorders, cardiac repair, autoimmune disease, obesity, atherosclerosis, etc. Reactive oxygen species (ROS) produced by the various cell types serve as signaling molecules in several cellular mechanisms and regulate various aspects of growth-factor-mediated responses, including lymphangiogenesis. The ROS, including superoxide anion, hydrogen peroxide, and nitric oxide, play both beneficial and detrimental roles depending upon their levels and cellular microenvironment. Low ROS levels are essential for lymphangiogenesis. On the contrary, oxidative stress due to enhanced ROS generation and/or reduced levels of antioxidants suppresses lymphangiogenesis via promoting lymphatic endothelial cell apoptosis and death. In this review article, we provide an overview of types and sources of ROS, discuss the role of ROS in governing lymphangiogenesis and lymphatic function, and summarize the role of lymphatics in various diseases.

Lymphatic Tissue Bioengineering for the Treatment of Postsurgical Lymphedema

Lymphedema is characterized by progressive and chronic tissue swelling and inflammation from local accumulation of interstitial fluid due to lymphatic injury or dysfunction. It is a debilitating condition that significantly impacts a patient's quality of life, and has limited treatment options. With better understanding of the molecular mechanisms and pathophysiology of lymphedema and advances in tissue engineering technologies, lymphatic tissue bioengineering and regeneration have emerged as a potential therapeutic option for postsurgical lymphedema. Various strategies involving stem cells, lymphangiogenic factors, bioengineered matrices and mechanical stimuli allow more precisely controlled regeneration of lymphatic tissue at the site of lymphedema without subjecting patients to complications or iatrogenic injuries associated with surgeries. This review provides an overview of current innovative approaches of lymphatic tissue bioengineering that represent a promising treatment option for postsurgical lymphedema.

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.

Pharmacological Treatment of Secondary Lymphedema

Lymphedema is a chronic disease that results in swelling and decreased function due to abnormal lymphatic fluid clearance and chronic inflammation. In Western countries, lymphedema most commonly develops following an iatrogenic injury to the lymphatic system during cancer treatment. It is estimated that as many as 10 million patients suffer from lymphedema in the United States alone. Current treatments for lymphedema are palliative in nature, relying on compression garments and physical therapy to decrease interstitial fluid accumulation in the affected extremity. However, recent discoveries have increased the hopes of therapeutic interventions that may promote lymphatic regeneration and function. The purpose of this review is to summarize current experimental pharmacological strategies in the treatment of lymphedema.

Three-dimensional analysis of dermal backflow in cancer-related lymphedema using photoacoustic lymphangiography

Background

Dermal backflow (DBF), which refers to lymphatic reflux due to lymphatic valve insufficiency, is a diagnostic finding in lymphedema. However, the three-dimensional structure of DBF remains unknown. Photoacoustic lymphangiography (PAL) is a new technique that enables the visualization of the distribution of light-absorbing molecules, such as hemoglobin or indocyanine green (ICG), and can provide three-dimensional images of superficial lymphatic vessels and the venous system. This study reports the use of PAL to visualize DBF structures in the extremities of patients with lymphedema after cancer surgery.

Methods

Patients with a clinical or lymphographic diagnosis of lymphedema who previously underwent surgery for cancer at one of two participating hospitals were included in this study. PAL was performed using the PAI-05 system. ICG was administered subcutaneously in the affected hand or foot, and ICG fluorescence lymphography was performed using a nearinfrared camera system prior to PAL.

Results

Between April 2018 and January 2019, 21 patients were enrolled and examined using PAL. The DBF was composed of dense, interconnecting, three-dimensional lymphatic vessels. It was classified into three patterns according to the composition of the lymphatic vessels: a linear structure of lymphatic collectors (pattern 1), a network of lymphatic capillaries and lymphatic collectors in an underlying layer (pattern 2), and lymphatic capillaries and precollectors with no lymphatic collectors (pattern 3).

Conclusions

PAL showed the structure of DBF more precisely than ICG fluorescence lymphography. The use of PAL to visualize DBF assists in understanding the pathophysiology and assessing the severity of cancer-related lymphedema.

Lymphangion-chip: a microphysiological system which supports co-culture and bidirectional signaling of lymphatic endothelial and muscle cells

The pathophysiology of several lymphatic diseases, such as lymphedema, depends on the function of lymphangions that drive lymph flow. Even though the signaling between the two main cellular components of a lymphangion, endothelial cells (LECs) and muscle cells (LMCs), is responsible for crucial lymphatic functions, there are no in vitro models that have included both cell types. Here, a fabrication technique (gravitational lumen patterning or GLP) is developed to create a lymphangion-chip. This organ-on-chip consists of co-culture of a monolayer of endothelial lumen surrounded by multiple and uniformly thick layers of muscle cells. The platform allows construction of a wide range of luminal diameters and muscular layer thicknesses, thus providing a toolbox to create variable anatomy. In this device, lymphatic muscle cells align circumferentially while endothelial cells aligned axially under flow, as only observed in vivo in the past. This system successfully characterizes the dynamics of cell size, density, growth, alignment, and intercellular gap due to co-culture and shear. Finally, exposure to pro-inflammatory cytokines reveals that the device could facilitate the regulation of endothelial barrier function through the lymphatic muscle cells. Therefore, this bioengineered platform is suitable for use in preclinical research of lymphatic and blood mechanobiology, inflammation, and translational outcomes.

Isolating and characterizing lymphatic endothelial progenitor cells for potential therapeutic lymphangiogenic applications

Lymphatic dysfunction is associated with the progression of several vascular disorders, though currently, there are limited strategies to promote new lymphatic vasculature (i.e., lymphangiogenesis) to restore lost lymphatic function. One promising approach to stimulate lymphangiogenesis involves delivering endothelial progenitor cells (EPCs), which are naturally involved in de novo blood vessel formation and have recently been identified to include a lymphatic subpopulation. However, the contribution of lymphatic EPCs in lymphangiogenesis is not clear and challenges with maintaining the activity of transplanted EPCs remain. Thus, the objective of this study was to isolate lymphatic EPCs from human umbilical cord blood and characterize their role in the initial stages of blood or lymphatic vasculature formation. Furthermore, this study also tested the applicability of alginate hydrogels to deliver lymphatic EPCs for a possible therapeutic application. We postulated and confirmed that blood and lymphatic EPC colonies could be isolated from human umbilical cord blood. Additionally, EPC populations responded to either angiogenic or lymphangiogenic growth factors and could stimulate their respective mature endothelial cells in vasculature models in vitro. Finally, lymphatic EPCs maintained their ability to promote lymphatic sprouts after prolonged interactions with the alginate hydrogel microenvironment. These results suggest EPCs have both a blood and a lymphatic population that have specific roles in promoting revascularization and highlight the potential of alginate hydrogels for the delivery of lymphatic EPCs. STATEMENT OF SIGNIFICANCE: Despite the potential therapeutic benefit of promoting lymphatic vasculature, lymphangiogenesis remains understudied. One appealing strategy for promoting lymphangiogenesis involves delivering lymphatic endothelial progenitor cells (EPCs), which are a subpopulation of EPCs involved in de novo vessel formation. Here, we investigate the role of isolated blood and lymphatic EPC subpopulations in promoting the early stages of vascularization and the utility of alginate hydrogels to deliver lymphatic EPCs. We determined that EPCs had two populations that expressed either blood or lymphatic markers, could stimulate their respective mature vasculature in tissue constructs and that alginate hydrogels maintained the therapeutic potential of lymphatic EPCs. We anticipate this work could support promising biomaterial applications of EPCs to promote revascularization, which could have many therapeutic applications.

Lymphedema Index Ratio As Predictive Factor of Treatment in Patients with Breast Cancer-Related Lymphedema

Background: This retrospective observational study aimed to evaluate the lymphedema index ratio to predict the effect of complex decongestive therapy (CDT) in patients with breast cancer-related lymphedema (BCRL) and to establish a lymphedema index ratio cutoff value for the extent of CDT effect. Materials and Methods: All 108 enrolled patients with BCRL underwent volume measurements and bioelectrical impedance analysis before and after CDT. The difference in percent excess volume (PEV) before and after CDT was defined as the therapeutic effect, and each patient was assigned to Groups A, B, or C based on therapeutic effects of 0%-5%, 5%-10%, and 10%-20%, respectively. Results: The mean lymphedema index ratios of Groups A, B, and C were 1.27, 1.38, and 1.46, respectively, with significant differences between the groups (p < 0.01). The cutoff lymphedema index ratio values for diagnosis between Groups A and B and between Groups B and C were 1.277 (sensitivity: 71.7%, specificity: 61.8%) and 1.357 (sensitivity: 76.9%, specificity: 62.1%), respectively. The Spearman coefficients for the linear relationship between lymphedema index ratio and initial PEV and between lymphedema index ratio and therapeutic effect were found to be significant at 0.615 and 0.360, respectively (p < 0.01). Conclusion: The results of this study found that the lymphedema index ratio may predict the volume reduction in patients with BCRL. A less reduction (therapeutic effect <5%) was predicted in patients with a lymphedema index ratio of <1.277, while a greater reduction (therapeutic effect >10%) was predicted in patients with a lymphedema index ratio of >1.357.

Vascularized omental lymphatic transplant for upper extremity lymphedema: A systematic review

BACKGROUND

Vascularized omental lymphatic transplant (VOLT) is an increasingly popular treatment of extremity lymphedema given its promising donor site. While the success of VOLT in the treatment of lymphedema has been reported previously, several questions remain.

AIM

To further elucidate appropriate use of VOLT in the treatment of lymphedema, specifically addressing patient selection, harvest technique, and operative methods.

METHODS AND RESULTS

A systematic review of VOLT for upper extremity lymphedema was performed. Of 115 yield studies, seven were included for analysis based on inclusion and exclusion criteria. Included studies demonstrated significant reductions in extremity circumference/volume (average volume reduction, 22.7%-39.5%) as well as subjective improvements using patient-reported outcomes. Though studies are heterogenous and limited, when analyzed in aggregate, suggest the efficacy of VOLT in lymphedema treatment.

CONCLUSION

This is the largest systematic review of VOLT to date. VOLT continues to show promise as a safe and efficacious surgical intervention for lymphedema in the upper extremity. Further studies are warranted to more definitively identify patients for whom this technique is appropriate as well as ideal harvest and inset technique.

Biochemical and mechanical signals in the lymphatic vasculature

Lymphatic vasculature is an integral part of the cardiovascular system where it maintains interstitial fluid balance. Additionally, lymphatic vasculature regulates lipid assimilation and inflammatory response. Lymphatic vasculature is composed of lymphatic capillaries, collecting lymphatic vessels and valves that function in synergy to absorb and transport fluid against gravitational and pressure gradients. Defects in lymphatic vessels or valves leads to fluid accumulation in tissues (lymphedema), chylous ascites, chylothorax, metabolic disorders and inflammation. The past three decades of research has identified numerous molecules that are necessary for the stepwise development of lymphatic vasculature. However, approaches to treat lymphatic disorders are still limited to massages and compression bandages. Hence, better understanding of the mechanisms that regulate lymphatic vascular development and function is urgently needed to develop efficient therapies. Recent research has linked mechanical signals such as shear stress and matrix stiffness with biochemical pathways that regulate lymphatic vessel growth, patterning and maturation and valve formation. The goal of this review article is to highlight these innovative developments and speculate on unanswered questions.

Outcomes of Lymphovenous Anastomosis for Upper Extremity Lymphedema: A Systematic Review

BACKGROUND

Lymphovenous anastomosis (LVA) is an accepted microsurgical treatment for lymphedema of the upper extremity (UE). This study summarizes and analyzes recent data on the outcomes associated with LVA for UE lymphedema at varying degrees of severity.

METHODS

A literature search was conducted in the PubMed database to extract articles published through June 19, 2020. Studies reporting data on postoperative improvement in limb circumference/volume or subjective improvement in quality of life for patients with primary or secondary lymphedema of the UE were included. Extracted data consisted of demographic data, number of patients and upper limbs, duration of symptoms before LVA, surgical technique, follow-up, and objective and subjective outcomes.

RESULTS

A total of 92 articles were identified, of which 16 studies were eligible for final inclusion comprising a total of 349 patients and 244 upper limbs. The average age of patients ranged from 38.4 to 64 years. The duration of lymphedema before LVA ranged from 9 months to 7 years. The mean length of follow-up ranged from 6 months to 8 years. Fourteen studies reported an objective improvement in limb circumference or volume measurements following LVA, ranging from 0% to 100%. Patients included had varying severity of lymphedema, ranging from Campisi stage I to IV. The maximal improvement in objective measurements was found in patients with lower stage lymphedema.

CONCLUSION

LVA is a safe, effective technique for the treatment of UE lymphedema refractory to decompressive treatment. Results of LVA indicate greater efficacy in earlier stages of lymphedema before advanced lymphatic sclerosis.