Development of a rat model of lymphedema and the implantation of a collagen-based medical device for therapeutic intervention

Secondary lymphedema is a common condition among cancer survivors, and treatment strategies to prevent or treat lymphedema are in high demand. The development of novel strategies to diagnose or treat lymphedema would benefit from a robust experimental animal model of secondary lymphedema. The purpose of this methods paper is to describe and summarize our experience in developing and characterizing a rat hindlimb model of lymphedema. Here we describe a protocol to induce secondary lymphedema that takes advantage of micro computed tomography imaging for limb volume measurements and visualization of lymph drainage with near infrared imaging. To demonstrate the utility of this preclinical model for studying the therapeutic benefit of novel devices, we apply this animal model to test the efficacy of a biomaterials-based implantable medical device.

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.

Croix B, Caron KM. Orphan G-Protein Coupled Receptor GPRC5B Is Critical for Lymphatic Development

Numerous studies have focused on the molecular signaling pathways that govern the development and growth of lymphatics in the hopes of elucidating promising druggable targets. G protein-coupled receptors (GPCRs) are currently the largest family of membrane receptors targeted by FDA-approved drugs, but there remain many unexplored receptors, including orphan GPCRs with no known biological ligand or physiological function. Thus, we sought to illuminate the cadre of GPCRs expressed at high levels in lymphatic endothelial cells and identified four orphan receptors: GPRC5B, AGDRF5/GPR116, FZD8 and GPR61. Compared to blood endothelial cells, GPRC5B is the most abundant GPCR expressed in cultured human lymphatic endothelial cells (LECs), and in situ RNAscope shows high mRNA levels in lymphatics of mice. Using genetic engineering approaches in both zebrafish and mice, we characterized the function of GPRC5B in lymphatic development. Morphant gprc5b zebrafish exhibited failure of thoracic duct formation, and Gprc5b^-/- mice suffered from embryonic hydrops fetalis and hemorrhage associated with subcutaneous edema and blood-filled lymphatic vessels. Compared to Gprc5^+/+ littermate controls, Gprc5b^-/- embryos exhibited attenuated developmental lymphangiogenesis. During the postnatal period, ~30% of Gprc5b^-/- mice were growth-restricted or died prior to weaning, with associated attenuation of postnatal cardiac lymphatic growth. In cultured human primary LECs, expression of GPRC5B is required to maintain cell proliferation and viability. Collectively, we identify a novel role for the lymphatic-enriched orphan GPRC5B receptor in lymphangiogenesis of fish, mice and human cells. Elucidating the roles of orphan GPCRs in lymphatics provides new avenues for discovery of druggable targets to treat lymphatic-related conditions such as lymphedema and cancer.

Multimodality Approach to Lymphedema Surgery Achieves and Maintains Normal Limb Volumes: A Treatment Algorithm to Optimize Outcomes

Surgical treatment of advanced lymphedema is challenging and outcomes are suboptimal. Physiologic procedures including lymphaticovenous anastomosis (LVA) and vascularized lymph node transfer (VLNT) improve lymphatic flow but cannot reverse fibrofatty tissue deposition, whereas liposuction removes fibrofatty tissue but cannot prevent disease progression. The adjunctive use of nanofibrillar collagen scaffolds (BioBridge^TM) can promote lymphangiogenesis. We report a treatment algorithm utilizing a multimodality approach to achieve sustained normal limb volumes in patients with stage II-III lymphedema. A retrospective review of late stage II-III lymphedema patients treated with liposuction, physiologic procedures, and BioBridge^TM from 2016 through 2019 was conducted. Treatment outcome in the form of excess volume reduction is reported. Total of 14 patients underwent surgical treatment of late stage II and III lymphedema according to our triple therapy algorithm. Patients had a baseline median volume excess of 29% (19.8, 43.3%). The median volume excess was improved to 0.5% (−4.3, 3.8%) at 14.4 months from the first stage surgery (p < 0.05) and further improved to −1.0% (−3.3, 1.3%) after triple therapy with BB placement at 24.6 months. A triple therapy surgical treatment algorithm can optimize outcomes and achieve sustained normalization of limb volume in late stage II-III lymphedema. The incorporation of nanofibrillar collagen scaffold technology allows for improved and sustained volume reduction.

Elevated magnetic resonance imaging measures of adipose tissue deposition in women with breast cancer treatment-related lymphedema

PURPOSE

Breast cancer treatment-related lymphedema (BCRL) is a common co-morbidity of breast cancer therapies, yet factors that contribute to BCRL progression remain incompletely characterized. We investigated whether magnetic resonance imaging (MRI) measures of subcutaneous adipose tissue were uniquely elevated in women with BCRL.

METHODS

MRI at 3.0 T of upper extremity and torso anatomy, fat and muscle tissue composition, and T₂ relaxometry were applied in left and right axillae of healthy control (n = 24) and symptomatic BCRL (n = 22) participants to test the primary hypothesis that fat-to-muscle volume fraction is elevated in symptomatic BCRL relative to healthy participants, and the secondary hypothesis that fat-to-muscle volume fraction is correlated with MR relaxometry of affected tissues and BCRL stage (significance criterion: two-sided p < 0.05).

RESULTS

Fat-to-muscle volume fraction in healthy participants was symmetric in the right and left sides (p = 0.51); in BCRL participants matched for age, sex, and BMI, fat-to-muscle volume fraction was elevated on the affected side (fraction = 0.732 ± 0.184) versus right and left side in controls (fraction = 0.545 ± 0.221, p < 0.001). Fat-to-muscle volume fraction directly correlated with muscle T₂ (p = 0.046) and increased with increasing level of BCRL stage (p = 0.041).

CONCLUSION

Adiposity quantified by MRI is elevated in the affected upper extremity of women with BCRL and may provide a surrogate marker of condition onset or severity.

CLINICAL TRIAL

NCT02611557.

Lymphatic regeneration after implantation of aligned nanofibrillar collagen scaffolds: Preliminary preclinical and clinical results

BACKGROUND

We tested our hypothesis that implantation of aligned nanofibrillar collagen scaffolds (BioBridge™) can both prevent and reduce established lymphedema in the rat lymphedema model. Our authors report clinical cases that demonstrate new lymphatic formation guided by BioBridge™ as seen by near-infrared (NIR) fluoroscopy and magnetic resonance (MR) lymphography.

METHODS

A rat lymphedema model was utilized. A prevention group received implantation of BioBridge™ immediately after lymphadenectomy. A lymphedema group received implantation of BioBridge™ with autologous adipose-derived stem cells (ADSC; treatment group) or remained untreated (control group). All subjects were observed for 4 months after lymphadenectomy. The hindlimb change was evaluated using computed tomography-based volumetric analysis. Lymphagiogenesis was assessed by indocyanine green (ICG) lymphography.

RESULTS

Animals in the treatment group showed a reduction in affected limb volume. Animals in the prevention group showed no increase in the affected limb volume. ICG fluoroscopy demonstrated lymph flow and formation of lymphatics toward healthy lymphatics.

CONCLUSIONS

In the rat lymphedema model, implantation of BioBridge™ at the time of lymph node removal prevents the development of lymphedema. Treatment of established lymphedema with the BioBridge™ and ADSC reduces lymphedema. New lymphatic vessels are demonstrated by NIR fluoroscopy and MR lymphography. These findings have implications for the treatment of lymphedema in human subjects.

Involvement of Sigma Receptor-1 in Lymphatic Endothelial Barrier Integrity and Bioenergetic Regulation

Background: Lymphatic endothelium plays significant roles in lymph transport and maintaining a barrier between the lymph and interstitial compartments. Lymphatic endothelial dysfunction is suspected to be a key factor in the pathogenesis of lymphatic diseases such as lymphedema. Sigma receptor-1 (σ1) was recently identified to promote endothelial-dependent production of nitric oxide and relaxation of collecting lymphatic vessels. In this study, we investigated the potential role of σ1 in lymphatic endothelial barrier function. Methods and Results: Cultured adult human dermal lymphatic endothelial cells (HDLEC) were grown into confluent monolayers. Transendothelial electrical resistance (TER) served as an index of barrier function. Glycolytic rate of HDLEC was determined with the Agilent Seahorse system. The σ1-selective agonist PRE-084 was used to test the impact of σ1 on HDLEC monolayer barrier function and endothelial bioenergetics, whereas the contribution of basal σ1 activity was assessed with small interfering RNA (siRNA)-mediated knockdown of σ1 expression. The ability of σ1 activation to counteract interleukin (IL)-1β-induced barrier dysfunction was also tested. The results show that PRE-084 increases HDLEC TER in a concentration-dependent manner, whereas reducing σ1 expression with siRNA decreases HDLEC TER. PRE-084 also enhances glycolytic rate parameters in HDLEC. Moreover, PRE-084 treatment partially counteracts IL-1β-induced HDLEC monolayer barrier dysfunction. Conclusions: Collectively, the results suggest that σ1 contributes to basal lymphatic endothelial barrier function, potentially through its ability to enhance glycolytic energy production. Our work also highlights the therapeutic potential of σ1 agonists for preventing lymphatic barrier dysfunction caused by inflammatory mediators.

Diagnosis and Management of Lymphatic Disorders in Congenital Heart Disease

Purpose of Review

Lymphatic disorders have received an increasing amount of attention over the last decade. Sparked primarily by improved imaging modalities and the dawn of lymphatic interventions, understanding, diagnostics, and treatment of lymphatic complications have undergone considerable improvements. Thus, the current review aims to summarize understanding, diagnostics, and treatment of lymphatic complications in individuals with congenital heart disease.

Recent Findings

The altered hemodynamics of individuals with congenital heart disease has been found to profoundly affect morphology and function of the lymphatic system, rendering this population especially prone to the development of lymphatic complications such as chylous and serous effusions, protein-losing enteropathy and plastic bronchitis.

Summary

Although improved, a full understanding of the pathophysiology and targeted treatment for lymphatic complications is still wanting. Future research into pharmacological improvement of lymphatic function and continued implementation of lymphatic imaging and interventions may improve knowledge, treatment options, and outcome for affected individuals.

Short-term molecular and cellular effects of ischemia/reperfusion on vascularized lymph node flaps in rats

Vascularized lymph node (VLN) transfer is an emerging strategy to re-establish lymphatic drainage in chronic lymphedema. However, the biological processes underlying lymph node integration remain elusive. This study introduces an experimental approach facilitating the analysis of short-term molecular and cellular effects of ischemia/reperfusion on VLN flaps. Lymph node flaps were dissected pedicled on the lateral thoracic vessels in 44 Lewis rats. VLN flaps were exposed to 45 or 120 minutes ischemia by in situ clamping of the vascular pedicle with subsequent reperfusion for 24 hours. Flaps not exposed to ischemia/reperfusion served as controls. Lymph nodes and the perinodal adipose tissue were separately analyzed by Western blot for the expression of lymphangiogenic and angiogenic growth factors. Moreover, morphology, microvessel density, proliferation, apoptosis and immune cell infiltration of VLN flaps were further assessed by histology and immunohistochemistry. Ischemia for 120 minutes was associated with a markedly reduced cellularity of lymph nodes but not of the perinodal adipose tissue. In line with this, ischemic lymph nodes exhibited a significantly lower microvessel density and an increased expression of VEGF-D and VEGF-A. However, VEGF-C expression was not upregulated. In contrast, analyses of the perinodal adipose tissue revealed a more subtle decrease of microvessel density, while only the expression of VEGF-D was increased. Moreover, after 120 minutes ischemia, lymph nodes but not the perinodal adipose tissue exhibited significantly higher numbers of proliferating and apoptotic cells as well as infiltrated macrophages and neutrophilic granulocytes compared with non-ischemic flaps. Taken together, lymph nodes of VLN flaps are highly susceptible to ischemia/reperfusion injury. In contrast, the perinodal adipose tissue is less prone to ischemia/reperfusion injury.

Diagnostic approach to lower limb edema

Patients with lower limb edema are frequently referred to vascular specialists for evaluation. Multiple etiologies must be considered and often more than one cause may be present. Notably, the role of lymphatic system regardless of the underlying pathology has been underestimated. A thorough history and physical examination and a carefully considered laboratory and imaging evaluation are critical in differentiating causes. In this opinion article, we propose a diagnostic algorithm that incorporates a systematic approach to the patient with leg swelling and provides an efficient pathway for the differential diagnosis for this problem.

Comparison of effectiveness between warm acupuncture with local-distal points combination and local distribution points combination in breast cancer-related lymphedema patients: a study protocol for a multicenter, randomized, controlled clinical trial

Background

Lymphedema is the most common complication after breast cancer treatment, but management of lymphedema remains a clinical challenge. Several studies have reported the beneficial effect of acupuncture for treating breast cancer-related lymphedema (BCRL). Our objective is to verify the effectiveness of warm acupuncture on BCRL and compare the effectiveness of a local distribution acupoint combination with a local-distal acupoint combination for BCRL.

Methods

This is a study protocol for a multicenter, three-arm parallel, assessor blinded, randomized controlled trial. A total of 108 participants diagnosed as BCRL will be randomly allocated in equal proportions to a local distribution acupoint (LA) group, a local-distal acupoint (LDA) group, or a waiting-list (WL) group. The LA and LDA groups will receive 20 acupuncture treatment over 8 weeks with local distribution acupoint combination and local-distal acupoint combination, respectively. The WL group will receive acupuncture treatment after the study is concluded. The primary outcome is the mean change in inter-limb circumference difference from baseline to week 8. The secondary outcomes include volume measurement, skin hardness, common terminology criteria for adverse events 4.03 (edema limbs criteria), stages of lymphedema from the International Society of Lymphology, Disabilities of the Arm, Shoulder and Hand questionnaire, and the Medical Outcome Study 36-item Short-form Health Survey.

Discussion

This study aims to provide data on warm acupuncture as an effective treatment for BCRL and at the same time compare the effectiveness of different acupoint combinations.

Trial registration

ClinicalTrials.gov: Identifier NCT03373474. Registered on 14th December 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3491-4) contains supplementary material, which is available to authorized users.

The role of adjunct nanofibrillar collagen scaffold implantation in the surgical management of secondary lymphedema: Review of the literature and summary of initial pilot studies

Secondary lymphedema is a worldwide affliction that exacts a significant public health burden. This review examines the etiology, presentation, and management of secondary lymphedema. In addition, emerging adjunctive strategies are explored, specifically evidence from animal and pilot human studies regarding implantation of a collagen nanofibrillar scaffold (BioBridge™; Fibralign Corporation, Union City, CA) in promoting lymphangiogenesis, preventing and treating lymphedema, and enhancing outcomes with lymphaticovenous anastomosis and vascularized lymph node transfer.

Upper limb secondary lymphedema ultrasound mapping and characterization

BACKGROUND

Ultrasound investigation potentials in lymphedema are still to be fully used in everyday practice. Aim of the present study was to report the sonographic characterization of the dermo-epidermal complex (DEC) and of the subcutaneous (SUBC) tissue, assessing the feasibility of a related mapping, in upper limb secondary lymphedema.

METHODS

In this retrospective study 287 patients affected by monolateral upper limb post-mastectomy lymphedema (M5/F282; mean age 64±4.24) were enrolled and scanned by ultrasound, considering the healthy contralateral limb as control. In order to standardize the assessment, the limb was divided in sectors: 4 anterior, 4 posterior below the elbow, 4 anterior and 4 posterior above the elbow, plus the hand. DEC and SUBC regions B-mode appearance were reported, both in the healthy and in the pathological arms. DEC thickness was measured and compared among the same sectors of the healthy and pathological limbs.

RESULTS

DEC and SUBC sonographic appearance was differentiated in fluid and sclerotic. DEC included a third category characterized by differentiation loss. The different sectors showed significantly different lymphatic involvement in the affected limb. In the comparison with the contralateral unaffected segments a significantly thicker DEC was reported in the forearm affected by lymphedema (P<0.005), while no significant difference was reported at the arm level.

CONCLUSIONS

Traditional ultrasonography can provide a secondary upper limb lymphedema characterization with related mapping and useful data for a better lymphatic physiopathology understanding and for a properly addressed therapeutic protocol.

High-resolution 3D volumetry versus conventional measuring techniques for the assessment of experimental lymphedema in the mouse hindlimb

Secondary lymphedema is a common complication of cancer treatment characterized by chronic limb swelling with interstitial inflammation. The rodent hindlimb is a widely used model for the evaluation of novel lymphedema treatments. However, the assessment of limb volume in small animals is challenging. Recently, high-resolution three-dimensional (3D) imaging modalities have been introduced for rodent limb volumetry. In the present study we evaluated the validity of microcomputed tomography (μCT), magnetic resonance imaging (MRI) and ultrasound in comparison to conventional measuring techniques. For this purpose, acute lymphedema was induced in the mouse hindlimb by a modified popliteal lymphadenectomy. The 4-week course of this type of lymphedema was first assessed in 6 animals. In additional 12 animals, limb volumes were analyzed by μCT, 9.4 T MRI and 30 MHz ultrasound as well as by planimetry, circumferential length and paw thickness measurements. Interobserver correlation was high for all modalities, in particular for μCT analysis (r = 0.975, p < 0.001). Importantly, caliper-measured paw thickness correlated well with μCT (r = 0.861), MRI (r = 0.821) and ultrasound (r = 0.800). Because the assessment of paw thickness represents a time- and cost-effective approach, it may be ideally suited for the quantification of rodent hindlimb lymphedema.

Functioning in lymphoedema from the health professionals' perspective using the international classification of functioning, disability and health as a reference

PURPOSE

To capture the views of different health care providers involved in the treatment of patients with lymphoedema from various countries around the world on the functioning of lymphoedema patients and the factors influencing functioning of these patients using the international classification of functioning, disability and health (ICF).

METHOD

A worldwide e-mail survey with questions based on components of the ICF.

RESULTS

In total, 142 health professionals from seven different health professions and 20 different countries answered the questions. The aspects of functioning that were named by the health professionals could be linked to 359 different ICF categories. Of these categories, 109 belonged to body functions (30.4%), 55 to body structures (15.3%), 121 to activities and participation (33.7%) and 74 to environmental factors (20.6%). Overall, the most mentioned items were health services, systems and policies, immunological system functions, looking after one's health, products and technology for personal use in daily life and dressing.

CONCLUSIONS

The ICF provided a valuable reference for identifying concepts in statements from international health care professionals experienced in the treatment of lymphoedema patients. The results of this research will be used in the development of ICF core sets for lymphoedema.

Lymphedema prevalence and treatment benefits in cancer: impact of a therapeutic intervention on health outcomes and costs

Background

Lymphedema is a common complication of cancer therapeutics; its prevalence, treatment outcomes, and costs have been poorly defined. The objective of this study was to examine lymphedema prevalence among cancer survivors and to characterize changes in clinical outcomes and costs associated with a defined therapeutic intervention (use of a pneumatic compression devices [PCD]) in a representative, privately insured population.

Methods and Findings

Retrospective analysis of de-identified health claims data from a large national insurer for calendar years 2007 through 2013. Patients were required to have 12 months of continuous insurance coverage prior to PCD receipt (baseline), as well as a 12-month follow-up period. Analyses were performed for individuals with cancer-related lymphedema (n = 1,065). Lymphedema prevalence was calculated: number of patients with a lymphedema claim in a calendar year divided by total number of enrollees. The impact of PCD use was evaluated by comparing rates of a pre-specified set of health outcomes and costs for the 12 months before and after, respectively, PCD receipt. Lymphedema prevalence among cancer survivors increased from 0.95% in 2007 to 1.24% in 2013. PCD use was associated with decreases in rates of hospitalizations (45% to 32%, p<0.0001), outpatient hospital visits (95% to 90%, p<0.0001), cellulitis diagnoses (28% to 22%, p = 0.003), and physical therapy use (50% to 41%, p<0.0001). The average baseline health care costs were high ($53,422) but decreased in the year after PCD acquisition (−$11,833, p<0.0001).

Conclusions

Lymphedema is a prevalent medical condition that is often a defining attribute of cancer survivorship. The problem is associated with high health care costs; Treatment (in this instance, use of PCD) is associated with significant decreases in adverse clinical outcomes and costs.

Quantitative and morphologic change associated with breast cancer-related lymphedema. Comparison of 3.0T MRI to external measures

Abstract Introduction: Lymphedema is a chronic disease of increasing importance to cancer survivors. A tape measurement tool used for lymphedema relies on indirect volume calculations based on external circumference, which may not reflect the true extent of abnormal fluid accumulation accurately. Fluid-sensitive MRI sequences may be able to delineate the severity of this condition more precisely and thus also monitor response to therapy.

METHODS AND RESULTS

Eight patients being followed by physical therapy for clinically diagnosed breast cancer-related lymphedema were recruited to participate in this study. External measurements and upper extremity MRI were performed on all subjects. Arm circumference, arm volume, and lymphedema volumes were calculated for each method. MR imaging detected lymphedema in all study subjects. Correlation was found between external circumferential measurements and with the 3.0T MRI (r=0.9368). There was poor correlation between lymphedema volumes calculated from clinical measurements and MR imaging (r=0.5539).

CONCLUSIONS

External measurements were not found to be an accurate measure of lymphedema volume associated with breast cancer lymphedema. MRI is a reliable means to obtain upper extremity circumferential and volume measurements. MRI is able to evaluate morphologic change associated with breast cancer-related lymphedema. Lymphedema research requires integrated use of tools to further describe the disease process over time, quantitate the distribution of tissue changes, and improve the sensitivity and specificity of the measurements.

The lymphatics and the inflammatory response: lessons learned from human lymphedema

In lymphedema, there is a profound predisposition to infection with bacterial pathogens. It therefore seems appropriate to reconsider our unique functional definition of the lymphatic structures within a circulatory construct. While the lymphatics unquestionably fulfill a vital circulatory function, it seems more appropriate to view this complex network, comprised both of endothelial-lined vessels and of lymphoid tissue, as the nexus between the circulatory and immune systems. Viewed in this fashion, it becomes evident that the complex biology of regional lymphatic disruption is a manifestation of the interplay between these two vital bodily functions. Experimental lymph stasis in murine model has been utilized to effectively demonstrate the pathological attributes of human lymphedema, namely, inflammation, fat deposition, and fibrosis. Large-scale transcriptional corroborates the role of inflammatory mechanisms. The murine studies have set the stage for subsequent translational investigation of human lymphedema. Many of the gene expression pathways invoked by lymphedema are relevant to the inflammatory response and have provided a pragmatic approach to the successful identification of potentially relevant circulating biomarkers for human lymphedema.

Sensitivity and specificity of fluorescence microlymphography for detecting lymphedema of the lower extremity

Fluorescence microlymphography (FML) is used to visualize the lymphatic capillaries. A maximum spread of the fluorescence dye of ≥ 12 mm has been suggested for the diagnosis of lymphedema. However, data on sensitivity and specificity are lacking. The aim of this study was to investigate the accuracy of FML for diagnosing lymphedema in patients with leg swelling. Patients with lower extremity swelling were clinically assessed and separated into lymphedema and non-lymphatic edema groups. FML was studied in all affected legs and the maximum spread of lymphatic capillaries was measured. Test accuracy and receiver operator characteristic (ROC) analysis was performed to assess possible threshold values that predict lymphedema. Between March 2008 and August 2011 a total of 171 patients (184 legs) with a median age of 43.5 (IQR 24, 54) years were assessed. Of those, 94 (51.1%) legs were diagnosed with lymphedema. The sensitivity, specificity, positive and negative likelihood ratio and positive and negative predictive value were 87%, 64%, 2.45, 0.20, 72% and 83% for the 12-mm cut-off level and 79%, 83%, 4.72, 0.26, 83% and 79% for the 14-mm cut-off level, respectively. The area under the ROC curve was 0.82 (95% CI: 0.76, 0.88). Sensitivity was higher in the secondary versus primary lymphedema (95.0% vs 74.3%, p = 0.045). No major adverse events were observed. In conclusion, FML is a simple and safe technique for detecting lymphedema in patients with leg swelling. A cut-off level of ≥ 14-mm maximum spread has a high sensitivity and high specificity of detecting lymphedema and should be chosen.

Prospective transcriptomic pathway analysis of human lymphatic vascular insufficiency: identification and validation of a circulating biomarker panel

BACKGROUND

In our previous transcriptional profiling of a murine model, we have identified a remarkably small number of specific pathways with altered expression in lymphedema. In this investigation, we utilized microarray-based transcriptomics of human skin for an unbiased a priori prospective candidate identification, with subsequent validation of these candidates through direct serum assay. The resulting multi-analyte biomarker panel sensitively should sensitively discriminate human lymphedema subjects from normal individuals.

METHODS AND FINDINGS

We enrolled 63 lymphedema subjects and 27 normals in our attempt to discover protein analytes that can distinguish diseased individuals from controls. To minimize technical and biologically irrelevant variation, we first identified potential candidates by performing transcriptional microarray analysis on paired diseased and normal skin specimens sampled from the same individuals. We focused our attention on genes with corresponding protein products that are secreted and took these candidates forward to a protein multiplex assay applied to diseased and normal subjects. We developed a logistic regression-based model on an eventual group of six proteins and validated our system on a separate cohort of study subjects. The area under the receiver operating characteristic curve was calculated to be 0.87 (95% CI : 0.75 to 0.97).

CONCLUSIONS

We have developed an accurate bioassay utilizing proteins representing four central pathogenetic modalities of the disease: lymphangiogenesis, inflammation, fibrosis, and lipid metabolism, suggesting that these proteins are directly related to the pathogenesis of the tissue pathology in lymphatic vascular insufficiency. Further studies are warranted to determine whether this newly-identified biomarker panel will possess utility as an instrument for in vitro diagnosis of early and latent disease; the ultimate applicability to risk stratification, quantitation of disease burden, and response to therapy can easily be envisioned.

Cancer-Related Lymphedema Risk Factors, Diagnosis, Treatment, and Impact: A Review

Purpose

Cancer-related lymphedema (LE) is an incurable condition associated with lymph-involved cancer treatments and is an increasing health, quality of life (QOL), and cost burden on a growing cancer survivor population. This review examines the evidence for causes, risk, prevention, diagnosis, treatment, and impact of this largely unexamined survivorship concern.

Methods

PubMed and Medline were searched for cancer-related LE literature published since 1990 in English. The resulting references (N = 726) were evaluated for strength of design, methods, sample size, and recent publication and sorted into categories (ie, causes/prevention, diagnosis, treatment, and QOL). Sixty studies were included.

Results

Exercise and physical activity and sentinel lymph node biopsy reduce risk, and overweight and obesity increase risk. Evidence that physiotherapy reduces risk and that lymph node status and number of malignant nodes increase risk is less strong. Perometry and bioimpedence emerged as attractive diagnostic technologies, replacing the use of water displacement in clinical practice. Swelling can also be assessed by measuring arm circumference and relying on self-report. Symptoms can be managed, not cured, with complex physical therapy, low-level laser therapy, pharmacotherapy, and surgery. Sequelae of LE negatively affect physical and mental QOL and range in severity. However, the majority of reviewed studies involved patients with breast cancer; therefore, results may not be applicable to all cancers.

Conclusion

Research into causes, prevention, and effect on QOL of LE and information on LE in cancers other than breast is needed. Consensus on definitions and measurement, increased patient and provider awareness of signs and symptoms, and proper and prompt treatment/access, including psychosocial support, are needed to better understand, prevent, and treat LE.

Update on the biology and treatment of lymphedema

OPINION STATEMENT

The past decade has produced an explosion of insights into lymphatic vascular development and structural biology and, in parallel, into the function of the lymphatics in health and in disease. In lymphedema, there is a spectrum that extends from primary (heritable) to acquired causes of disease. The diagnosis of lymphatic edema implicates a very specific treatment approach that is predicated upon the favorable impact of physiotherapy upon lymph flow and protein clearance from the edematous zones of the body. The recognition of the unique biology that accompanies lymphatic causes of edema has stimulated new research directions that are likely to translate into exciting new pharmacologic and molecular approaches to diagnosis and treatment.

Modelling the lymphatic system: challenges and opportunities

The lymphatic system is a vital part of the circulatory and immune systems, and plays an important role in homeostasis by controlling extracellular fluid volume and in combating infection. Nevertheless, there is a notable disparity in terms of research effort expended in relation to the treatment of lymphatic diseases in contrast to the cardiovascular system. While similarities to the cardiovascular system exist, there are considerable differences in their anatomy and physiology. This review outlines some of the challenges and opportunities for those engaged in modelling biological systems. The study of the lymphatic system is still in its infancy, the vast majority of the models presented in the literature to date having been developed since 2003. The number of distinct models and their variants are few in number, and only one effort has been made thus far to study the entire lymphatic network; elements of the lymphatic system such as the nodes, which act as pumps and reservoirs, have not been addressed by mathematical models. Clearly, more work will be necessary in combination with experimental verification in order to progress and update the knowledge on the function of the lymphatic system. As our knowledge and understanding of its function increase, new and more effective treatments of lymphatic diseases are bound to emerge.

Normal interstitial flow is critical for developmental lymphangiogenesis in the zebrafish

BACKGROUND

The lymphatic system plays a critical role in the body's fluid and protein homeostasis, immune regulation, and dietary fat absorption. One of the major pathologies of the lymphatic system is primary lymphedema, which occurs in approximately 0.6% of live births and is caused by missing or impaired lymphatic vessels. Although there is a great need for medical intervention into diseases of the lymphatic system, very little is known about its development or how it maintains integrity over time. Recent studies have suggested that biophysical components, such as local extracellular fluid flow, may be important factors during initiation of lymphangiogenesis. We hypothesize that interstitial fluid flow functions as an important morphoregulator during developmental lymphangiogenesis.

METHODS AND RESULTS

In the present study we use pharmacological agents and a mutant fish line to modulate interstitial flow. Our data confirm that a sufficient increase or decrease in interstitial flow can profoundly affect lymphatic patterning and may result in a lymphedema-like phenotype. Proper interstitial flow appears to be necessary during LEC migration for proper lymphatic development.

CONCLUSIONS

These results support the contention that interstitial flow is an important morphoregulator of developmental lymphangiogenesis.