Interactions between nanoparticles and lymphatic systems: Mechanisms and applications in drug delivery

The lymphatic system has garnered significant attention in drug delivery research due to the advantages it offers, such as enhancing systemic exposure and enabling lymph node targeting for nanomedicines via the lymphatic delivery route. The journey of drug carriers involves transport from the administration site to the lymphatic vessels, traversing the lymph before entering the bloodstream or targeting specific lymph nodes. However, the anatomical and physiological barriers of the lymphatic system play a pivotal role in influencing the behavior and efficiency of carriers. To expedite research and subsequent clinical translation, this review begins by introducing the composition and classification of the lymphatic system. Subsequently, we explore the routes and mechanisms through which nanoparticles enter lymphatic vessels and lymph nodes. The review further delves into the interactions between nanomedicine and body fluids at the administration site or within lymphatic vessels. Finally, we provide a comprehensive overview of recent advancements in lymphatic delivery systems, addressing the challenges and opportunities inherent in current systems for delivering macromolecules and vaccines.

Isolated scrotal lymphedema in a 43-year old male patient: A case report

INTRODUCTION

Lymphedema of the external genitalia is a rare condition characterized by swelling of the scrotal skin and subcutaneous tissue, resulting from a pathology in lymphatic drainage. Over time, the development of fibrosis leads to a considerable impairment in the patient's quality of life. While conservative management is generally the first-line approach, surgical cases may necessitate surgical intervention to achieve comprehensive and lasting improvements.

CASE PRESENTATION

We present the case of a 43-year-old obese male patient who presented to the clinic with a complaint of persistent bilateral scrotal swelling for three months. Clinical examination revealed a pressure-indolent, soft, and massively enlarged swelling of the scrotum on both sides. Ultrasound findings confirmed a diffusely thickened edematous scrotal wall. The patient was advised to start physiotherapy and adhere to conservative management. Due to the debilitating size of the mass, the patient opted for excision of the scrotal swelling followed by scrotoplasty.

CLINICAL DISCUSSION

This case report explores the presentation, signs and symptoms, impact on patients' lives, and various management options for scrotal lymphedema. It underscores the intricacies involved in the diagnosis and treatment decision-making process, emphasizing the need for a tailored and multidisciplinary approach.

CONCLUSION

It is imperative to initially rule out life-threatening causes of scrotal lymphedema to ensure optimal patient care. The integration of surgical interventions should be carefully considered in the overall management strategy for optimal and comprehensive results. Scrotoplasty, in the context of scrotal lymphedema, not only improves the quality of life but also positively influences sexual function.

COMPETENCIES

Interpersonal and communication skills, Medical knowledge, Patient care, Practice-based learning and improvement.

Refractory chylous ascites revealing follicular lymphoma: A case report

INTRODUCTION AND IMPORTANCE

Chylous ascites is an uncommon form of ascites characterized by milky fluid rich in triglycerides. It is associated with poor lymphatic drainage. We report a case of chylous ascites revealing a follicular lymphoma.

CASE PRESENTATION

A 73-year-old man presented with a 6-month history of abdominal distension attributed to a chylous ascitis. The thoraco-abdomino-pelvic CT scan revealed voluminous intra- and retroperitoneal mass inseparable from the duodeno-pancreatic block and encompassing the mesenteric vessels, inferior vena cava and renal vessels; abundant ascites and multiple mediastinal, coeliomesenteric, retroperitoneal, iliac and inguinal adenomegalia. The diagnosis of follicular lymphoma was retained through a radio-guided biopsy of the retroperitoneal mass. The patient had weekly paracentesis and immuno-chemotherapy. The course was unfavorable, marked by infection of the ascites fluid after two cycles of immuno-chemotherapy. Our patient developed severe sepsis and died.

CLINICAL DISCUSSION

Chylous ascites in conjunction with follicular lymphoma is an exceptional presentation. The pathophysiological mechanism is an impediment to subdiaphragmatic lymphatic drainage caused by external pressure, leading to leakage of dilated subserosal lymphatic ducts into the peritoneal cavity. Histological confirmation is fundamental to manage chylous ascites resulting from lymphomas.

CONCLUSION

Chylous ascites revealing lymphoma is a unique condition. The key to management is the treatment of the underlying etiology.

Current and Developing Lymphatic Imaging Approaches for Elucidation of Functional Mechanisms and Disease Progression

Study of the lymphatic system, compared to that of the other body systems, has been historically neglected. While scientists and clinicians have, in recent decades, gained a better appreciation of the functionality of the lymphatics as well as their role in associated diseases (and consequently investigated these topics further in their experimental work), there is still much left to be understood of the lymphatic system. In this review article, we discuss the role lymphatic imaging techniques have played in this recent series of advancements and how new imaging techniques can help bolster this wave of discovery. We specifically highlight the use of lymphatic imaging techniques in understanding the fundamental anatomy and physiology of the lymphatic system; investigating the development of lymphatic vasculature (using techniques such as intravital microscopy); diagnosing, staging, and treating lymphedema and cancer; and its role in other disease states.

Computational fluid dynamic modeling of the lymphatic system: a review of existing models and future directions

Historically, research into the lymphatic system has been overlooked due to both a lack of knowledge and limited recognition of its importance. In the last decade however, lymphatic research has gained substantial momentum and has included the development of a variety of computational models to aid understanding of this complex system. This article reviews existing computational fluid dynamic models of the lymphatics covering each structural component including the initial lymphatics, pre-collecting and collecting vessels, and lymph nodes. This is followed by a summary of limitations and gaps in existing computational models and reasons that development in this field has been hindered to date. Over the next decade, efforts to further characterize lymphatic anatomy and physiology are anticipated to provide key data to further inform and validate lymphatic fluid dynamic models. Development of more comprehensive multiscale- and multi-physics computational models has the potential to significantly enhance the understanding of lymphatic function in both health and disease.

Crohn's disease as the intestinal manifestation of pan-lymphatic dysfunction: An exploratory proposal based on basic and clinical data

Crohn's disease (CD) is caused by immune, environmental, and genetic factors. It can involve the entire gastrointestinal tract, and although its prevalence is rapidly increasing its etiology remains unclear. Emerging biological and small-molecule drugs have advanced the treatment of CD; however, a considerable proportion of patients are non-responsive to all known drugs. To achieve a breakthrough in this field, innovations that could guide the further development of effective therapies are of utmost urgency. In this review, we first propose the innovative concept of pan-lymphatic dysfunction for the general distribution of lymphatic dysfunction in various diseases, and suggest that CD is the intestinal manifestation of pan-lymphatic dysfunction based on basic and clinical preliminary data. The supporting evidence is fully summarized, including the existence of lymphatic system dysfunction, recognition of the inside-out model, disorders of immune cells, changes in cell plasticity, partial overlap of the underlying mechanisms, and common gut-derived fatty and bile acid metabolism. Another benefit of this novel concept is that it proposes adopting the zebrafish model for studying intestinal diseases, especially CD, as this model is good at presenting and mimicking lymphatic dysfunction. More importantly, the ensuing focus on improving lymphatic function may lead to novel and promising therapeutic strategies for CD.

Novel Interventional Radiology for the Treatment of Various Lymphatic Leakages: Lymphatic Intervention and Embolization

Little progress has been made in modern lymphatic medicine since Dr. Kinmonth first described pedal lymphangiography in the 1950s. The clinical need for an effective treatment modality for managing lymphatic leakage greatly increased only after intranodal lymphangiography, which enabled the depiction of the exact location of the leakage. This review introduces five hypotheses that have been proposed while addressing various clinical scenarios involving lymphatic leakage: (1) various embolization techniques can be used to prevent lymphatic leakage; (2) lymph node embolization can treat postoperative pelvic lymphoceles that are refractory to sclerotherapy; (3) the technical success rate of thoracic duct cannulation can be improved by using retrograde thoracic duct access as a bail-out method; (4) non-traumatic chylothorax can be managed by understanding the underlying pathophysiology; and (5) chylous ascites can be managed by understanding the underlying pathophysiology. Five retrospective observational studies, one randomized prospective clinical trial, and two case reports (letters to the editor) were published after the hypotheses were validated. We provide a new systematic approach to lymphatic intervention by describing the process of the current comprehensive research.

Serum soluble LYVE1 is a promising non-invasive biomarker of renal fibrosis: a population-based retrospective cross-sectional study

Diagnosis of renal fibrosis can only be verified by kidney biopsy, but biomarkers for non-invasive evaluation remain unsatisfactory. Patients with fibrosis often have abnormalities of the lymphatic vascular system and associated immune function. We describe here a lymphatic marker as a candidate biomarker for fibrosis. After assessing and grading the fibrosis scores, testing serum soluble lymphatic vessel endothelial hyaluronan receptor1 (sLYVE1) level, and collecting clinical information, the association between sLYVE1 and renal fibrosis was analyzed. Logistic regression analysis was used to screen variables. Diagnosis models with or without sLYVE1 were built, and nomograms were plotted. Calibration curve, C-index, and DCA were performed to assess the models. A total of 298 patients were enrolled in the study, of which 199 were included in the training cohort and 99 patients in the validation cohort. Serum sLYVE1 levels markedly elevated with increasing fibrosis grade (p<0.05). ROC analysis of sLYVE1 showed an AUC of 0.791 and 0.846 with optimal cut-off value of 405.25 ng/mL and 498.55 ng/mL for the prediction of moderate-to-severe renal fibrosis (MSF) and severe renal fibrosis (SF), respectively. The diagnostic nomogram model without sLYVE1 (model 1) included traditional clinical determinants (C-index: 0.658 for MSF; 0.603 for SF). A combination of model 1 and sLYVE1 (model 2) improved predictive performance (C-index: 0.847 for MSF; 0.856 for SF). Calibration curve and DCA demonstrated a better consistency accuracy and clinical benefit of model 2 than model 1. Serum sLYVE1 may be identified as a potential biomarker of renal fibrosis. Models incorporating sLYVE1 may be beneficial for a more accurate non-invasive diagnosis of renal fibrosis.

Evaluation of the Superficial Collecting Lymph Vessels' Vasa Vasorum in Lymphoedematous Limbs Using Video Capillaroscopy

OBJECTIVE

The pre-collecting and collecting lymph vessels have smooth muscle cells, and sufficient perfusion is vital to maintain their function. Although the vasa vasorum of the collecting lymph vessels (VVCL) have been histologically investigated, little is known about their physiology. This study aimed to investigate the relationship between morphology and blood flow of the VVCL in lymphoedematous limbs.

METHODS

Medical records of lower extremity lymphoedema patients who underwent video capillaroscopy observation during supermicrosurgical lymphaticovenous anastomosis (LVA) surgery were reviewed. The collecting lymph vessels, dissected for LVA, were examined under video capillaroscopy (GOKO Bscan-ZD, GOKO Imaging Devices Co., Japan) with a magnification of 175x and 620x. Blood flow velocity of the VVCL was calculated by measuring the red blood cell movement using software (GOKO-VIP ver. 1.0.0.4, GOKO Imaging Devices Co., Japan). Based on the video capillaroscopy findings, the VVCL were grouped according to their morphology; the VVCL morphology types and blood flow velocity were then compared according to the lymphosclerosis severity grade.

RESULTS

Sixty-seven lymph vessels in 20 lower extremity lymphoedema patients were evaluated, including s0 in 19 (28.4%), s1 in 34 (50.7%), s2 in 10 (14.9%), and s3 in four (6.0%) lymph vessels. The VVCLs were grouped into four types: type 1 (n = 4), type 2 (n = 37), type 3 (n = 19), and type 4 (n = 7). Blood flow velocity of the VVCL ranged 0 - 189.3 μm/sec (average 26.40 μm/sec). There were statistically significant differences in VVCL morphology (p < .001) and blood flow velocity (p < .001) according to lymphosclerotic severity.

CONCLUSION

Vasa vasorum of the collecting lymph vessels could be grouped into four types with different characteristics. Morphological and physiological changes of the VVCL were related to sclerotic changes of the collecting lymph vessels.

Advances in photoacoustic imaging aided by nano contrast agents: special focus on role of lymphatic system imaging for cancer theranostics

Photoacoustic imaging (PAI) is a successful clinical imaging platform for management of cancer and other health conditions that has seen significant progress in the past decade. However, clinical translation of PAI based methods are still under scrutiny as the imaging quality and clinical information derived from PA images are not on par with other imaging methods. Hence, to improve PAI, exogenous contrast agents, in the form of nanomaterials, are being used to achieve better image with less side effects, lower accumulation, and improved target specificity. Nanomedicine has become inevitable in cancer management, as it contributes at every stage from diagnosis to therapy, surgery, and even in the postoperative care and surveillance for recurrence. Nanocontrast agents for PAI have been developed and are being explored for early and improved cancer diagnosis. The systemic stability and target specificity of the nanomaterials to render its theranostic property depends on various influencing factors such as the administration route and physico-chemical responsiveness. The recent focus in PAI is on targeting the lymphatic system and nodes for cancer diagnosis, as they play a vital role in cancer progression and metastasis. This review aims to discuss the clinical advancements of PAI using nanoparticles as exogenous contrast agents for cancer theranostics with emphasis on PAI of lymphatic system for diagnosis, cancer progression, metastasis, PAI guided tumor resection, and finally PAI guided drug delivery.

brucei population

Trypanosoma brucei colonise and multiply in the blood vasculature, as well as in various organs of the host's body. Lymph nodes have been previously shown to harbour large numbers of parasites, and the lymphatic system has been proposed as a key site that allows T. brucei distribution through, and colonization of the mammalian body. However, visualization of host-pathogen interactions in the lymphatic system has never captured dynamic events with high spatial and temporal resolution throughout infection. In our work, we used a mixture of tools including intravital microscopy and ex vivo imaging to study T. brucei distribution in 20 sets of lymph nodes. We demonstrate that lymph node colonization by T. brucei is different across lymph node sets, with the most heavily colonised being the draining lymph nodes of main tissue reservoirs: the gonadal white adipose tissue and pancreas. Moreover, we show that the lymphatic vasculature is a pivotal site for parasite dispersal, and altering this colonization by blocking LYVE-1 is detrimental for parasite survival. Additionally, parasites within the lymphatic vasculature have unique morphological and behavioural characteristics, different to those found in the blood, demonstrating that across both types of vasculature, these environments are physically separated. Finally, we demonstrate that the lymph nodes and the lymphatic vasculature undergo significant alterations during T. brucei infection, resulting in oedema throughout the host's body.

Comparison of sentinel lymph node distribution and lymphatic drainage pathway between high- and low-risk endometrial cancers

PURPOSE

This study aimed to compare the distribution and drainage pathway of sentinel lymph nodes between high- and low-risk endometrial cancers.

METHODS

In total, 429 patients with endometrial cancer who underwent sentinel lymph node biopsy in Peking University People's Hospital from July 2015 to April 2022 were retrospectively enrolled. There were 148 patients in the high-risk group and 281 patients in the low-risk group.

RESULTS

The unilateral and bilateral detection rates of sentinel lymph nodes were 86.5% and 55.9%, respectively. The highest detection rate was achieved in the subgroup with a combined use of indocyanine green (ICG) and carbon nanoparticles (CNP) (94.4% for unilateral detection and 66.7% for bilateral detection). The upper paracervical pathway (UPP) was detected in 93.3% of cases in the high-risk group and 96.0% of cases in the low-risk group (p = 0.261). The lower paracervical pathway (LPP) was detected in 10.0% of cases in the high-risk group and 17.9% of cases in the low-risk group (p = 0.048). Remarkably increased detection rates of SLN in the common iliac (7.5%) and para-aortic or precaval areas (2.9%) were observed in the high-risk group. In contrast, a markedly decreased detection rate of SLN in the internal iliac area (1.9%) was observed in the high-risk group.

CONCLUSION

The highest detection rate of SLN was observed in the subgroup with a combined use of ICG and CNP. The detection of UPP is important for both high-risk and low-risk cases, while LPP detection plays a more important role in the low-risk group. Lymphadenectomy in the common iliac and para-aortic or precaval areas is essential for patients with high-risk EC. Removal of internal iliac lymph nodes is essential for patients with low-risk EC, in case of ineffective SLN mapping.

Logistics and distribution of small extracellular vesicles from the subcutaneous space to the lymphatic system

Small extracellular vesicles (sEVs) are small, cell-derived particles with sizes of approximately 100 nm. Since these particles include cargos such as host cell-derived proteins, messenger RNAs, and micro RNAs, they serve as mediators of cell-cell communication. While the analysis of the pharmacokinetic of sEVs after the intravenous injection have been reported, the lymphatic transport of sEVs remains unclear. The objective of this study was to provide insights into the intra-lymphatic trafficking and distribution of sEVs when they are injected into an interstitial space both in normal skin tissue and in cancerous tissue. When sEVs were Subcutaneously administered into the tail base and the tumor tissue, they preferably accumulated in the lymph nodes (LNs), rather than in the liver and the spleen. The findings reported herein show that the lymphatic transport of sEVs was drastically changed in model mice, in which a surgical treatment was used to modify to allow the dominant lymphatic flow from the footpad directly to the axillary LN via the inguinal LN. Based on the results, we conclude that when sEVs are injected into the subcutis space, they are preferably delivered to the LN via the lymphatic system. Further, the extent of accumulation of sEVs in the LN after subcutaneous injection was reduced when they were preliminarily incubated with Proteinase K. These results suggest that the lymphatic drainage of sEVs in normal skin tissue is regulated by membrane proteins on their surface. This reduction, however, was not observed in the case of cancer tissue. This discrepancy can be attributed to the presence of highly permeable lymphatic vessels in the tumor tissue. Further, the major cell subtypes that captured sEVs in the LN were LN-resident medullary sinus macrophages. These collective findings indicate that the lymphatic drainage of sEVs are mediated by proteins and, that they may appear to contribute to the control of the function of immune-responsive cells in the LNs.

Perirenal lymphatics: anatomy, pathophysiology, and imaging spectrum of diseases

Despite being rarely discussed, perinephric lymphatics are involved in many pathological and benign processes. The lymphatic system in the kidneys has a harmonious dynamic with ureteral and venous outflow, which can result in pathology when this dynamic is disturbed. Although limited by the small size of lymphatics, multiple established and emerging imaging techniques are available to visualize perinephric lymphatics. Manifestations of perirenal pathology may be in the form of dilation of perirenal lymphatics, as with peripelvic cysts and lymphangiectasia. Lymphatic collections may also occur, either congenital or as a sequela of renal surgery or transplantation. The perirenal lymphatics are also intimately involved in lymphoproliferative disorders, such as lymphoma as well as the malignant spread of disease. Although these pathologic entities often have overlapping imaging features, some have distinguishing characteristics that can suggest the diagnosis when paired with the clinical history.

[Genetics, diagnostics and clinical presentation of primary lymphoedema]

Primary lymphoedema is a hereditary genetic disorder of the lymphatic system. These genetic disorders can result in malformation or dysfunction of the lymphatic system, which leads to an accumulation of fluid in the tissue and, thus to the formation of oedema. The most common form is peripheral lymphoedema of the lower limbs, but systemic manifestations such as intestinal lymphangiectasia, ascites, chylothorax or hydrops fetalis may also occur. The clinical presentation and the degree of lymphoedema varies depending on the causative gene and the specific gene alteration. Primary lymphoedema is divided into five categories: (1) disorders with somatic mosaicism and segmental growth abnormality, (2a) syndromal disorders, (2b) disorders with systemic involvement, (2c) congenital lymphoedema and (2d) disorders that occur after the first year of life (late onset lymphoedema). Targeted genetic diagnosis is based on the patient's clinical presentation and classification into one of the five categories. In general, the diagnosis usually starts with basic diagnostics, which include cytogenetic and molecular genetic testing. Subsequently, a molecular genetic diagnosis is made by performing single-gene analyses, gene panel examinations, exome sequencing or whole genome sequencing. This allows the identification of genetic variants or mutations that are considered to be causative for the presenting symptoms. Combined with human genetic counselling, the genetic diagnosis allows for conclusions about inheritance, the risk of recurrence and potential concomitant symptoms. In many cases, only this approach allows the definite form of primary lymphoedema to be described.

Lymphatic complex transfer as combined lymph vessel and node transfer for advanced stage upper extremity lymphedema

OBJECTIVE

Lymphedema, especially in the advanced stage, is a growing challenge in extremity reconstruction, with few applicable surgical methods. Despite its importance, no consensus has been reached regarding a single surgical method yet. Herein, the authors introduce a novel concept of lymphatic reconstruction yielding promising results.

METHODS

We included 37 patients with advanced-stage upper extremity lymphedema who underwent lymphatic complex transfers, consisting of both lymph vessel and node transfers, from 2015 to 2020. We compared the preoperative and postoperative (last visit) mean circumferences and volume ratios between the affected and unaffected limbs. Changes in the Lymphedema Life Impact Scale scores and complications were also investigated.

RESULTS

The circumference ratio (affected to unaffected limbs) improved at all measuring points (P < .05), while the volume ratio showed a decrease from 1.54 to 1.39 (P < .001). The mean Lymphedema Life Impact Scale decreased from 48.1 ± 15.2 to 33.4 ± 13.8 (P < .05). No donor site morbidities, including iatrogenic lymphedema or any other major complications, were observed.

CONCLUSIONS

A new technique for lymphatic reconstruction, lymphatic complex transfer, may be useful in cases of advanced stage lymphedema because of its effectiveness and the low possibility of donor site lymphedema.

The comparison of the effects of neuromuscular electrical stimulation and Kinesio Taping on ankle swelling in athletes with lateral ankle sprain

PURPOSE

Ankle swelling (AS) is one of the main complaints in athletes with a lateral ankle sprain (LAS) in the acute phase. Reducing AS may help the athlete to return to training faster. The purpose of this study was to evaluate the efficacy of Kinesio Taping® (KT) and neuromuscular electrical stimulation (NMES) in reducing AS in athletes with a LAS.

METHODS

Thirty-one athletes with a unilateral ankle sprain from various sports were allocated to either KT (N = 16; mean age of 24.1 years) or NMES (N = 15; mean age of 26.4 years) groups. KT was applied over the medial and lateral ankle surfaces in the Fan cut pattern for five consecutive days; however, NMES was applied to the tibialis anterior and gastrocnemius muscles for 30 min. Outcome measures to assess the extent of AS included volumetry, perimetry, relative volumetry, and the difference in both ankles' volumetry and perimetry at baseline, after the interventions, and 15 days following the treatment completion.

RESULTS

The results of the mixed model repeated measures ANOVA demonstrated no significant difference between the two groups in mean changes in outcomes over pre- and post-interventions as well as follow-up periods (P > 0.05).

CONCLUSIONS

None of the KT and NMES methods could reduce acute AS in athletes with LAS. Further studies are needed in this area of research that consider changes in treatment protocol given the variety of NMES approaches and KT applications that can be used in recovery from an ankle sprain.

Effectiveness of physical therapy in axillary web syndrome after breast cancer: a systematic review and meta-analysis

BACKGROUND

The axillary web syndrome (AWS) is a surgical breast cancer sequel that limits the functionality of the patient and delays the protocol times of application of cancer treatments. This implies a long period of discomfort and limitations for the user.

OBJECTIVE

To investigate the different physiotherapy treatments for the AWS and how effective they are.

METHODS

A systematic review based on PRISMA protocol and registered in PROSPERO (CRD42021281354) was conducted. The research was performed using PubMed, Scopus, CINAHL, PEDro, and Web of Science databases during January 2022 and March 2022. All randomized controlled trials and controlled clinical trials were included in this review.

RESULTS

A total of 188 articles were identified, with 9 studies selected for the systematic review. These studies basically propose treatments based on exercises and stretching, manual therapy, and the combination of manual therapy and exercises.

CONCLUSIONS

Exercise and stretching are the most effective therapies within the field of physiotherapy for the rehabilitation of axillary web syndrome. They restore range of motion faster, reduce pain, improve quality of life, and reduce disabilities. Manual therapy, scar massage, and myofascial release could help improve outcomes but with worse results. The meta-analysis conclusion is that pain is the only outcome with a significant reduction after the application of physiotherapy treatments - 0.82 [- 1.67; 0.03]. This conclusion is drawn from the only three studies with small sample sizes.

Intranodal cone-beam computed tomographic lymphangiography with water-soluble iodinated contrast agent for evaluating chylothorax in infants - preliminary experience at a single institution

This brief report demonstrates the diagnostic utility of cone-beam CT lymphangiography (CBCTL) with intranodal injection of water-soluble iodinated contrast agent for assessing lymphatic disorders in two infants who were contraindicated for MRI and oil-based contrast agent. Both infants had dextro-transposition of the great arteries (d-TGA) and presented with high-output chylothoraces that were recalcitrant to conservative medical therapy. Both infants were diagnosed with central lymphatic flow disorder based on the CBCTL findings.

Drug delivery to the brain via the nasal route of administration: exploration of key targets and major consideration factors

Background

Cranial nerve-related diseases such as brain tumors, Alzheimer's disease, and epilepsy are serious diseases that continue to threaten human. Brain-related diseases are increasing worldwide, including in the United States and Korea, and these increases are closely related to the exposure to harmful substances and excessive stress caused by rapid industrialization and environmental pollution. Drug delivery to the brain is very important for the effective prevention and treatment of brain-related diseases. However, due to the presence of the blood-brain barrier and the extensive first-pass metabolism effect, the general routes of administration such as oral and intravenous routes have limitations in drug delivery to the brain. Therefore, as an alternative, the nasal-brain drug delivery route is attracting attention as a route for effective drug delivery to the brain.

Areas covered

This review includes physiological factors, advantages, limitations, current application status, especially in clinical applications, and the necessary factors for consideration in formulation development related to nasal-brain drug delivery.

Expert opinion

The nasal-brain drug delivery route has the advantage of enhancing drug delivery to the brain locally, mainly through the olfactory route rather than the systemic circulation. The nasal-brain lymphatic system has recently attracted attention, and it has been implied that the delivery of anticancer drugs to the brain nervous system is possible effectively. However, there are limitations such as low drug permeability, as well as nasal mucosa and the mucociliary system, as obstacles in nasal-brain drug delivery. Therefore, to overcome the limitations of nasal-brain drug delivery, the use of nanocarriers and mucoadhesive agents is being attempted. However, very few drugs have been officially approved for clinical application via the nasal-brain drug delivery route. This is probably because the understanding of and related studies on nasal-brain drug delivery are limited. In this review, we tried to explore the major considerations and target factors in drug delivery through the nasal-brain route based on physiological knowledge and formulation research information. This will help to provide a mechanistic understanding of drug delivery through the nasal-brain route and bring us one step closer to developing effective formulations and drugs in consideration of the key factors for nasal-brain drug delivery.

Cystic hygroma in a female suckling pig: a case report

BACKGROUND

Cystic hygromas (lymphangiomas) are rarely reported in various animal species, humans included. A hygroma is a benign congenital malformation of the lymphatic drainage system, presenting itself as a mass consisting of multiple cysts of various sizes with a watery content.

CASE PRESENTATION

This report describes clinical, ultrasonographic, and post-mortem findings of a cystic hygroma in a suckling pig. The mass was characterized by a few thin-walled cysts, containing clear yellow serous fluid. Histologically, the central cavity was lined by a single layer of squamous cells, supported by a thick fibrous stroma. On immunohistochemistry, scattered lining cells were weakly positive for Factor-VIII, suggesting their possible endothelial origin.

CONCLUSIONS

This case report contributes to raising awareness on this condition in pigs allowing early identification in life so that appropriate care can be provided. The case report attributes to science on hygromas in general, as better understanding of pathologic features, the aetiology and appropriate treatment are needed.

Assessment of the lymphatic system by indirect lymphography in patients with post-thrombotic syndrome

OBJECTIVE

Alterations in lower extremity lymph drainage caused by chronic venous obstruction (CVO) have not been well studied, partially because of a lack of standardized imaging modalities to assess the quality of lymphatic drainage in the lower extremities of patients with post-thrombotic syndrome (PTS). However, these changes are likely to have an impact on the severity of the disease and clinical outcomes of interventions. In the present study, we investigated the feasibility and diagnostic value of preintervention indirect lymphography in patients with CVO and their pre- and postintervention Villalta scores.

METHODS

A total of 17 patients (21 limbs) with iliofemoral and caval CVO were included in the study between 2017 and 2018. The deep and superficial lymphatic vessels in both legs were assessed before venous recanalization and stenting. The quality of lymphatic flow was compared between the legs with CVO and healthy legs. Moreover, the correlation between the lymphatic changes and clinical severity of PTS was evaluated using the Villalta score and CEAP (Clinical, Etiology, Anatomy, and Pathophysiology) classification.

RESULTS

The mean patient age was 44 ± 12 years, and 10 patients (59%) were women. The patients had undergone treatment at a mean of 25 ± 6 months after their first episode of deep vein thrombosis. Five patients (29%) had had recurrent deep vein thrombosis. The mean pre- and postinterventional Villalta score was 10.5 ± 1.46 and 9.27 ± 1.12, respectively (P = .0096). Using the CEAP classification, four legs were class 5, seven were class 4, and three each were class 3 and 2. The primary and secondary patency rate was 70.5% and 82.5% after a mean follow-up of 18 months, respectively. Indirect lymphography of the superficial and deep lymphatic systems was completed before intervention in both legs for all 17 patients (21 legs). According to the qualitative criteria, abnormal lymphatic vessel function was found in 35.2% of the superficial and 58.8% of the deep lymphatic vessels of the affected legs. Further analysis revealed abnormal function of the deep lymphatic vessels in all patients with moderate to severe PTS according to the Villalta score.

CONCLUSIONS

Indirect lymphography is a feasible diagnostic tool to use for the evaluation of the function of lymphatic vessels. Impaired drainage of the deep lymphatic system was found in all our patients with moderate to severe PTS. The clinical significance of these lymphatic changes is not clear; however, an association between clinical severity and outcomes is possible.

Lymphatic anomalies in congenital heart disease

Congenital heart disease can lead to various lymphatic complications including traumatic leaks, lymphatic overproduction, conduction abnormalities or lymphedema. Advancements in the imaging of central lymphatics and guided interventions have improved outcomes in these children. Dynamic contrast-enhanced magnetic resonance (MR) lymphangiography allows for the assessment of abnormal lymphatic drainage. This technique is preferred for evaluating lymphatic conditions such as plastic bronchitis, chylothorax, chyloptysis, chylopericardium, protein-losing enteropathy and chylous ascites, among other lymphatic disorders. In this review, we discuss lymphatic abnormalities encountered on MRI in children with congenital heart disease. We also briefly review treatment options.

State-of-the-art imaging for lymphatic evaluation in children

The lymphatic system has been poorly understood and its importance neglected for decades. Growing understanding of lymphatic flow pathophysiology through peripheral and central lymphatic flow imaging has improved diagnosis and treatment options in children with lymphatic diseases. Flow dynamics can now be visualized by different means including dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL), the current standard technique to depict central lymphatics. Novel imaging modalities including intranodal, intrahepatic and intramesenteric DCMRL are quickly evolving and have shown important advances in the understanding and guidance of interventional procedures in children with intestinal lymphatic leaks. Lymphatic imaging is gaining importance in the radiologic and clinical fields and new techniques are emerging to overcome its limitations.

Lymphatic vessels in cancer

The lymphatic system, composed of initial and collecting lymphatic vessels as well as lymph nodes that are present in almost every tissue of the human body, acts as an essential transport system for fluids, biomolecules and cells between peripheral tissues and the central circulation. Consequently, it is required for normal body physiology but is also involved in the pathogenesis of various diseases, most notably cancer. The important role of tumor-associated lymphatic vessels and lymphangiogenesis in the formation of lymph node metastasis has been elucidated during the last two decades, whereas the underlying mechanisms and the relation between lymphatic and peripheral organ dissemination of cancer cells are incompletely understood. Lymphatic vessels are also important for tumor-host communication, relaying molecular information from a primary or metastatic tumor to regional lymph nodes and the circulatory system. Beyond antigen transport, lymphatic endothelial cells, particularly those residing in lymph node sinuses, have recently been recognized as direct regulators of tumor immunity and immunotherapy responsiveness, presenting tumor antigens and expressing several immune-modulatory signals including PD-L1. In this review, we summarize recent discoveries in this rapidly evolving field and highlight strategies and challenges of therapeutic targeting of lymphatic vessels or specific lymphatic functions in cancer patients.

Imaging of fluorescent polymer dots in relation to channels and immune cells in the lymphatic system

Polymer dots (Pdots) have been applied to imaging lymph nodes (LNs) and lymphatic vessels (LVs) in living mice and rats. However, the mechanism of absorption, distribution, metabolism, and excretion of Pdots in LNs and LVs is still unclear. Therefore, the relationship between Pdots and immune cells, LVs and collagen fibers in lymphatics was studied by multiple in vivo and ex vivo microscopic imaging methods and detection techniques. Flow cytometry showed that Pdots could be phagocytosed by macrophages and monocytes, and had no relationship with B cells, T cells and dendric cells in LNs. Silver staining, immunofluorescence and two-photon microscope showed that Pdots gathered in collagen fibers and LVs of LNs. Furthermore, immunofluorescence imaging results verified that Pdots were distributed in the extracellular space of collecting LVs endothelial cells. In addition, Pdots in the collecting LVs were basically cleared by leaking into the surrounding tissue or draining LNs after 21 days of injection. During the long-time observation, Pdots also helped monitor the contraction frequency and variation range of LV. Our study lays a foundation on the research of Pdots as the carrier to study lymphatic structure and function in the future.

Part 2: Model for the Drug-combination Nanoparticles

We previously developed a mechanism-based pharmacokinetic (MBPK) model to characterize the PK of a lymphocyte-targeted, long-acting 3 HIV drug-combination nanoparticle (DcNP) formulation of lopinavir, ritonavir, and tenofovir. MBPK describes time-courses of plasma drug concentration and has provided an initial hypothesis for the lymphatic PK of DcNP. Because anatomical and physiological interpretation of MBPK is limited, in this Part 2, we report the development of a Physiologically Based Pharmacokinetic (PBPK) model for a detailed evaluation of the systemic and lymphatic PK of drugs associated with DcNP. The DcNP model is linked to the PBPK model presented earlier in Part 1 to account for the disposition of released free drugs. A key feature of the DcNP model is the uptake of the injected dose from the subcutaneous site to the adjacent lymphoid depot, routing through the nodes within and throughout the lymphatic network, and its subsequent passage into the blood circulation. Furthermore, the model accounts for DcNP transport to the lymph by lymphatic recirculation and mononuclear cell migration. The present PBPK model can be extended to other nano-drug combinations that target or transit through the lymphatic system. The PBPK model may allow scaling and prediction of DcNP PK in humans.

Dynamic contrast-enhanced magnetic resonance lymphangiography

Lymphatic flow disorders include a broad spectrum of abnormalities that can originate in the lymphatic or the venous system. The development of these disorders is multifactorial and is most commonly associated with congenital heart diseases and palliative surgeries that these patients undergo. Central lymphatic disorders might be secondary to traumatic leaks, lymphatic overproduction, conduction abnormalities or lymphedema, and they can progress to perfusion anomalies. Several imaging modalities have been used to visualize the lymphatic system. However, the imaging of central lymphatic flow has always been challenging. Dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL) allows for visualization of central lymphatic flow disorders and has been recently applied for the assessment of plastic bronchitis, protein-losing enteropathy, chylothorax and chylopericardium, among other lymphatic disorders. The hepatic and mesenteric accesses are innovative and promising techniques for better identification and understanding of these abnormalities. The main objectives of this review are to discuss the physiology and anatomy of the lymphatic system and review the current uses of DCMRL in the diagnosis and management of lymphatic flow disorders.

Part 1: Model for the Free-Drug Mixture

Drug-combination nanoparticles (DcNP) allow the formulation of multiple HIV drugs in one injectable. In nonhuman primates (NHP), all drugs in DcNP have demonstrated long-acting pharmacokinetics (PK) in the blood and lymph nodes, rendering it suitable for a Targeted Long-acting Antiretroviral Therapy (TLC-ART). To support the translation of TLC-ART into the clinic, the objective is to present a physiologically based PK (PBPK) model tool to control mechanisms affecting the rather complex DcNP-drug PK. Two species contribute simultaneously to the drug PK: drugs that dissociate from DcNP (Part 1) and drugs retained in DcNP (Part 2, presented separately). Here, we describe the PBPK modeling of the nanoparticle-free drugs. The free-drug model was built on subcutaneous injections of suspended lopinavir, ritonavir, and tenofovir in NHP, and validated by external experiments. A novelty was the design of a lymphatic network as part of a whole-body PBPK system which included major lymphatic regions: the cervical, axillary, hilar, mesenteric, and inguinal nodes. This detailed/regionalized description of the lymphatic system and mononuclear cells represents an unprecedented level of prediction that renders the free-drug model extendible to other small-drug molecules targeting the lymphatic system at both the regional and cellular levels.

Animal Models Used in the Research of Vascularized Lymph Node Transfer: A Systematic Review

BACKGROUND

Lymphedema is a common adverse consequence of breast cancer therapy, while still relatively little is known about its pathophysiology. Several treatment options emerged over the past decades, and among them, vascularized lymph node transfer (VLNT) seems to be particularly promising. Animal models are indispensable to improve our understanding of the underlying processes surrounding the transplantation of a vascularized lymph node. This review aimed to systematically evaluate animal models of VLNT and compare their advantages and disadvantages.

MATERIALS AND METHODS

A systematic review of literature in the Scopus, Web of Science, and Ovid MEDLINE databases was conducted according to the PRISMA guidelines to identify all studies on animal models used for the research of VLNT. The algorithm used in search of articles was "Vascularized Lymph Node Transfer" AND "Model". Articles were manually verified for relevance to the topic. The resulting models were assessed for their suitability for VLNT research.

RESULTS

The literature search yielded a total of 233 studies after duplicates removal. Of those, 217 were excluded based on title and abstract review. Another study was excluded after reviewing the full-text article leaving 15 eligible studies to be included in this review article.

CONCLUSIONS

Rats were found to be the most dominantly used animal model in the VLNT research, although other models had their benefits. The main areas of study were the functionality of VLNT within or without a preinduced lymphedema, its response to ischemia, and clarification of lymphatic pathways reestablishment following VLNT.

Supermicrosurgical lymphovenous anastomosis for the treatment of recurrent cellulitis-associated lymphedema in the lower limb

Recurrent leg cellulitis can damage the lymphatic system and result in chronic lymphedema. Antibiotic therapy is administered to prevent cellulitis; however, antibiotic-resistant bacteria frequently occur. Supermicrosurgical lymphovenous anastomosis (LVA) can play a role in stopping the vicious circle by improving lymph circulation. In the present report, we have described the case of a 40-year-old male patient with frequent cellulitis and subsequent left leg edema. Based on the lymphoscintigraphy findings, LVA was performed on the left leg (six anastomoses). One year later, the lymphedema had subsided without further cellulitis. Lymphoscintigraphy revealed no dermal backflow. Thus, LVA is a treatment option for recurrent cellulitis-associated lymphedema.

Quantitation of lymphatic transport mechanism and barrier influences on lymph node-resident leukocyte access to lymph-borne macromolecules and drug delivery systems

Lymph nodes (LNs) are tissues of the immune system that house leukocytes, making them targets of interest for a variety of therapeutic immunomodulation applications. However, achieving accumulation of a therapeutic in the LN does not guarantee equal access to all leukocyte subsets. LNs are structured to enable sampling of lymph draining from peripheral tissues in a highly spatiotemporally regulated fashion in order to facilitate optimal adaptive immune responses. This structure results in restricted nanoscale drug delivery carrier access to specific leukocyte targets within the LN parenchyma. Herein, a framework is presented to assess the manner in which lymph-derived macromolecules and particles are sampled in the LN to reveal new insights into how therapeutic strategies or drug delivery systems may be designed to improve access to dLN-resident leukocytes. This summary analysis of previous reports from our group assesses model nanoscale fluorescent tracer association with various leukocyte populations across relevant time periods post administration, studies the effects of bioactive molecule NO on access of lymph-borne solutes to dLN leukocytes, and illustrates the benefits to leukocyte access afforded by lymphatic-targeted multistage drug delivery systems. Results reveal trends consistent with the consensus view of how lymph is sampled by LN leukocytes resulting from tissue structural barriers that regulate inter-LN transport and demonstrate how novel, engineered delivery systems may be designed to overcome these barriers to unlock the therapeutic potential of LN-resident cells as drug delivery targets.

Improved symptoms of complex regional pain syndrome after novel lymphatic treatment and interdisciplinary pain management

INTRODUCTION

Complex regional pain syndrome (CRPS) is a pain syndrome with no singular mechanism and no specific cure. The aim of this case report is to study the impact of Lymphatic Enhancement Technology (LET) treatment on CRPS-related symptoms.

METHODS

A 51 year-old female presented with a chief complaint of severe, refractory ankle pain and CRPS related to a tibial and fibular fracture sustained three years earlier. The patient completed twelve cognitive behavioral therapy sessions over a 4-week period, and eleven physical therapy sessions over a four-month period, six of which utilized LET.

RESULTS

Pain and swelling were largely unchanged with interdisciplinary treatment before the introduction of LET. A within-session change of 37.5% in pain intensity and 87.5% in ankle girth was observed immediately after the first application of LET. Three months after beginning LET treatment, the patient maintained a 43.8% improvement in pain intensity and 100% improvement in measurements of lower extremity girth and ankle range of motion. No side effects or adverse events were associated with the LET treatment.

CONCLUSION

Swelling, pain, and mobility loss are common symptoms and features of CRPS. LET is a novel, non-invasive treatment that appears to be quite safe and effective for improving pain, swelling, and mobility loss related to CRPS.

The lymphatic system and sentinel lymph nodes: conduit for cancer metastasis

The lymphatic system is a complicated system consisting of the lymphatic vessels and lymph nodes draining the extracellular fluid containing cellular debris, excess water and toxins to the circulatory system. The lymph nodes serve as a filter, thus, when the lymph fluid returns to the heart, it is completely sterile. In addition, the lymphatic system includes the mucosa-associated lymphoid tissue, such as tonsils, adenoids, Peyers patches in the small bowel and even the appendix. Taking advantage of the drainage system of the lymphatics, cancer cells enter the lymphatic vessels and then the lymph nodes. In general, the lymph nodes may serve as a gateway in the majority of cases in early cancer. Occasionally, the cancer cells may enter the blood vessels. This review article emphasizes the structural integrity of the lymphatic system through which cancer cells may spread. Using melanoma and breast cancer sentinel lymph node model systems, the spread of early cancer through the lymphatic system is progressive in a majority of cases. The lymphatic systems of the internal organs are much more complicated and difficult to study. Knowledge from melanoma and breast cancer spread to the sentinel lymph node may establish the basic principles of cancer metastasis. The goal of this review article is to emphasize the complexity of the lymphatic system. To date, the molecular mechanisms of cancer spread from the cancer microenvironment to the sentinel lymph node and distant sites are still poorly understood and their elucidation should take major priority in cancer metastasis research.

Edema assessment and management practice patterns among hand therapists: Survey research

STUDY DESIGN

Survey research.

INTRODUCTION

Recently, the lymphatic system's role in edema management has been reported; however, it is unclear how this evidence has translated into hand therapy practice.

PURPOSE OF THE STUDY

Survey research was performed to explore edema education and management.

METHODS

A 22-question survey containing questions related to edema education and practice was administered to members of the American Society of Hand Therapists. Demographic data were obtained. Frequencies were examined using Chi-square and Fisher exact tests.

RESULTS

A total of 436 members responded to the survey (92% occupational therapists [OTs]; 6% physical therapists [PTs]). Most hand therapists received edema education through on-the-job training and, or continuing education. PTs were more likely to learn the difference between acute, subacute, chronic edema (P < .01; 36% PTs, 17% OTs) and the role of the lymphatic system in edema management (P < .002; 36% PTs, 14% OTs) in entry-level education compared to OTs. OTs with an MS or OTD were more likely to learn the difference between acute, subacute, chronic edema (P < .001; 23% OTD, 24% MS, 10% BS) and the role of the lymphatic system in edema management (P < .004; 19% OTD, 19% MS, 7% BS) in entry-level education than BS-trained OTs. Duration and feel were common ways therapists assessed and identified differences in edema. Many therapists acknowledged the role of the lymphatic system in edema reduction, but responses lacked specificity.

CONCLUSION

The survey results suggest most hand therapists learn edema management outside of academic programs, although this may be changing in OT with advancement of the entry-level degree.

Lymphatic Drug Transport and Associated Drug Delivery Technologies: A Comprehensive Review

Lymphatic system is the secondary circulation system of the human body after the systemic circulation. Various problems, including the first-pass metabolism through oral administration of medicines, can be resolved by lymphatic targeting. Lymphatic absorption has been explored in detail, and studies reveal the improved bioavailability of medicines. In the case of cancer, AIDS, and various other health problems, lymphatic targeting has been focused on due to the fact that lymph nodes are involved greatly in tumor metastasis. This article reviews lymphatic absorption and its exploration in the treatment of various health problems. The physiology of the lymphatic system, the mechanisms of absorption, and the various formulation systems suitable for lymphatic absorption have been discussed. Some recent novel approaches like hydrodynamically driven device (HDD) and carbon nanotubes for lymphatic delivery have also been appraised.

Intraneural fibrosis and loss of microvascular architecture - Key findings investigating failed human nerve allografts

BACKGROUND

Processed nerve allografts are increasingly used in clinical nerve reconstruction with promising results. However, allograft failure has been reported, leading to chronic pain and persistent loss of function. In the present work, we performed a histological and immunohistochemical analysis of two failed allograft reconstructions of a sensory human nerve one year after primary surgery.

METHODS

Two patients with a superficial radial nerve injury underwent nerve reconstruction with processed nerve allografts. The clinical follow-up was complicated by severe neuropathic pain and absent sensory reinnervation. Consequently, the failed allografts were excised with subsequent histological and immunohistochemical examinations. For that purpose, the collagen content and neurofilament network as well as the blood and lymphatic vasculature were analysed in the center of the specimens.

RESULTS

Histology revealed increased fibrosis, fatty degeneration, and disorganised proliferation of nerve fibres. Moreover, the microvascular network within the allografts was characterised by increased numbers of microvessels, whereas no difference was found concerning the lymphatic vasculature.

CONCLUSION

The herein presented histological and immunohistochemical findings indicate that the failure of human allografts is associated with loss of the physiological microvascular architecture. Future studies elucidating the complex interplay of angiogenesis, lymphangiogenesis and axonal regeneration are required to better understand the mechanisms of human allograft failure.

Cellular and molecular mediators of lymphangiogenesis in inflammatory bowel disease

Background

Recent studies reporting the intricate crosstalk between cellular and molecular mediators and the lymphatic endothelium in the development of inflammatory bowel diseases (IBD) suggest altered inflammatory cell drainage and lymphatic vasculature, implicating the lymphatic system as a player in the occurrence, development, and recurrence of intestinal diseases. This article aims to review recent data on the modulatory functions of cellular and molecular components of the IBD microenvironment on the lymphatic system, particularly lymphangiogenesis. It serves as a promising therapeutic target for IBD management and treatment. The interaction with gut microbiota is also explored.

Main text

Evidence shows that cells of the innate and adaptive immune system and certain non-immune cells participate in the complex processes of inflammatory-induced lymphangiogenesis through the secretion of a wide spectrum of molecular factors, which vary greatly among the various cells. Lymphangiogenesis enhances lymphatic fluid drainage, hence reduced infiltration of immunomodulatory cells and associated-inflammatory cytokines. Interestingly, some of the cellular mediators, including mast cells, neutrophils, basophils, monocytes, and lymphatic endothelial cells (LECs), are a source of lymphangiogenic molecules, and a target as they express specific receptors for lymphangiogenic factors.

Conclusion

The effective target of lymphangiogenesis is expected to provide novel therapeutic interventions for intestinal inflammatory conditions, including IBD, through both immune and non-immune cells and based on cellular and molecular mechanisms of lymphangiogenesis that facilitate inflammation resolution.

Oral lipid nanomedicines: Current status and future perspectives in cancer treatment

Oral anticancer drugs have earned a seat at the table, as the need for homecare treatment in oncology has increased. Interest in this field is growing as a result of their proven efficacy, lower costs and positive patient uptake. However, the gastrointestinal barrier is still the main obstacle to surmount in chemotherapeutic oral delivery. Anticancer nanomedicines have been proposed to solve this quandary. Among these, lipid nanoparticles are described to be efficiently absorbed while protecting drugs from early degradation in hostile environments. Their intestinal lymphatic tropism or mucoadhesive/penetrative properties give them unique characteristics for oral administration. Considering that chronic cancer cases are increasing over time, it is important to be able to provide treatments with low toxicity and low prices. The challenges, opportunities and therapeutic perspectives of lipid nanoparticles in this area will be discussed in this review, taking into consideration the pre-clinical and clinical progress made in the last decade.

Imaging technology of the lymphatic system

The lymphatic system plays critical roles in tissue fluid homeostasis and immunity and has been implicated in the development of many different pathologies, ranging from lymphedema, the spread of cancer to chronic inflammation. In this review, we first summarize the state-of-the-art of lymphatic imaging in the clinic and the advantages and disadvantages of these existing techniques. We then detail recent progress on imaging technology, including advancements in tracer design and injection methods, that have allowed visualization of lymphatic vessels with excellent spatial and temporal resolution in preclinical models. Finally, we describe the different approaches to quantifying lymphatic function that are being developed and discuss some emerging topics for lymphatic imaging in the clinic. Continued advancements in lymphatic imaging technology will be critical for the optimization of diagnostic methods for lymphatic disorders and the evaluation of novel therapies targeting the lymphatic system.

Part VI: the microscopic discovery of the subtle anatomy

The discovery of chyle and lymph vessels had furthered the dream of understanding the body's structure and functions. Initially it was thought that chyle was sucked from the intestines through the open mouths of chyle vessels, and that lymph vessels were side branches of arterial end branches. In the second half of the 17th century, microscopy became an adjuvant for research into the subtle anatomy of the lymphatic system. In the present paper, we will focus on its initial use for the study of the structure and function of chyle and lymph vessels, and lymph glands.

Does Impaired Glymphatic Drainage Cause Glymphedema? A Review Tailored to Neurocritical Care and Neurosurgery

Research into the glymphatic system reached an inflection point with steep trajectory in 2012 when it was formally recognized and named, but the historical roots for it are solid and deep, dating back to pioneers such as Cushing, Weed, and Dandy. We provide an overview of key discoveries of the glymphatic system, which promotes bulk flow of fluid and solutes throughout the brain parenchyma. We also discuss the lymphatic drainage of the central nervous system. Evidence is building that failure of the glymphatic system causes glymphedema in patients commonly managed by neurocritical care and neurosurgery specialists. We review research supporting this for decompressive craniectomy, subarachnoid hemorrhage, and normal-pressure hydrocephalus. We argue that it is time for a paradigm shift from the traditional model of cerebrospinal fluid circulation to a revised model that incorporates the glymphatic pathway and lymphatic clearance. These recent breakthroughs will inspire new therapeutic approaches to recognize, reverse, and restore glymphatic dysfunction and to leverage this pathway to deliver brain-wide therapeutics.

COVID-19 and chronic fatigue syndrome: Is the worst yet to come?

There has been concern about possible long-term sequelae resembling myalgic encephalomyelitis/chronic fatigue syndrome in COVID-19 patients. Clarifying the mechanisms underlying such a "post-COVID-19 fatigue syndrome" is essential for the development of preventive and early treatment methods for this syndrome. In the present paper, by integrating insights pertaining to the glymphatic system and the nasal cerebrospinal fluid outflow pathway with findings in patients with chronic fatigue syndrome, idiopathic intracranial hypertension, and COVID-19, I provide a coherent conceptual framework for understanding the pathophysiology of post-COVID-19 fatigue syndrome. According to this hypothesis, this syndrome may result from damage to olfactory sensory neurons, causing reduced outflow of cerebrospinal fluid through the cribriform plate, and further leading to congestion of the glymphatic system with subsequent toxic build-up within the central nervous system. I further postulate that patients with post-COVID-19 fatigue syndrome may benefit from cerebrospinal fluid drainage by restoring glymphatic transport and waste removal from the brain. Obviously, further research is required to provide further evidence for the presence of this post-viral syndrome, and to provide additional insight regarding the relative contribution of the glymphatic-lymphatic system to it. Other mechanisms may also be involved. If confirmed, the glymphatic-lymphatic system could represent a target in combating post-COVID-19 fatigue syndrome. Moreover, further research in this area could also provide new insights into the understanding of chronic fatigue syndrome.

Imaging of fetal lymphangiectasias: prenatal and postnatal imaging findings

Lymphangiectasias are lymphatic malformations characterized by the abnormal dilation and morphology of the lymphatic channels. The classification and treatment of these disorders can be challenging given the limited amount of literature available in children. Various imaging modalities are used to confirm suspected diagnosis, plan the most appropriate treatment, and estimate a prognosis. Prenatal evaluation is performed using both prenatal US imaging and fetal MRI. These modalities are paramount for appropriate parental counseling and planning of perinatal care. During the neonatal period, chest US imaging is a useful modality to evaluate pulmonary lymphangiectasia because other modalities such as conventional radiography and CT display nonspecific findings. Finally, the recent breakthroughs in lymphatic imaging with MRI have allowed us to better classify lymphatic disorders. Dynamic contrast-enhanced lymphangiography, conventional lymphangiography and percutaneous lymphatic procedures offer static and dynamic evaluation of the central conducting lymphatics in children, with excellent spatial resolution and the possibility to provide treatment. The purpose of this review is to discuss the normal and abnormal development of the fetal lymphatic system and how to best depict it by imaging during the prenatal and postnatal life.

Cancer treatment in the lymphatic system: A prospective targeting employing nanostructured systems

Cancer related to lymphangiogenesis has gained a great deal of attention in recent decades ever since specific markers of this intriguing system were discovered. Unlike the blood system, the lymphatic system has unique features that can advance cancer in future metastasis, or, conversely, can provide an opportunity to prevent or treat this disease that affects people worldwide. The aim of this review is to show the recent research of cancer treatment associated with the lymphatic system, considered one of the main gateways for disseminating metastatic cells to distant organs. Nanostructured systems based on theranostics and immunotherapies can offer several options for this complex disease. Precision targeting and accumulation of nanomaterials into the tumor sites and their elimination, or targeting the specific immune defense cells to promote optimal regression of cancer cells are highlighted in this paper. Moreover, therapies based on nanostructured systems through lymphatic systems may reduce the side effects and toxicity, avoid first pass hepatic metabolism, and improve patient recovery. We emphasize the general understanding of the association between the immune and lymphatic systems, their interaction with tumor cells, the mechanisms involved and the recent developments in several nanotechnology treatments related to this disease.

Lymph-directed nitric oxide increases immune cell access to lymph-borne nanoscale solutes

Lymph nodes (LNs) are immune organs housing high concentrations of lymphocytes, making them critical targets for therapeutic immunomodulation in a wide variety of diseases. While there is great interest in targeted drug delivery to LNs, many nanoscale drug delivery carriers have limited access to parenchymal resident immune cells compared to small molecules, limiting their efficacy. Nitric oxide (NO) is a potent regulator of vascular and lymphatic transport and a promising candidate for modulating nanocarrier access to LNs, but its lymphatic accumulation is limited by its low molecular weight and high reactivity. In this work, we employ S-nitrosated nanoparticles (SNO-NP), a lymphatic-targeted delivery system for controlled NO release, to investigate the effect of NO application on molecule accumulation and distribution within the LN. We evaluated the LN accumulation, spatial distribution, and cellular distribution of a panel of fluorescent tracers after intradermal administration alongside SNO-NP or a small molecule NO donor. While SNO-NP did not alter total tracer accumulation in draining lymph nodes (dLNs) or affect active cellular transport of large molecules from the injection site, its application enhanced the penetration of nanoscale 30 nm dextrans into the LN and their subsequent uptake by LN-resident lymphocytes, while nontargeted NO delivery did not. These results further extended to a peptide-conjugated NP drug delivery system, which showed enhanced uptake by B cells and dendritic cells when administered alongside SNO-NP. Together, these results highlight the utility of LN-targeted NO application for the enhancement of nanocarrier access to therapeutically relevant LN-resident immune cells, making NO a potentially useful tool for improving LN drug delivery and immune responses.

[Diagnostic imaging of malignant lymphomas]

BACKROUND

Malignant lymphomas represent approximately 5% of all cancers. Imaging procedures play a crucial role concerning initial staging and assessment of the response to treatment.

OBJECTIVE

This article gives an overview of the significance of imaging procedures in the treatment of patients with malignant lymphomas at various times during treatment. These include the initial assessment of the extent of the disease and staging during and after treatment under consideration of the current classification systems.

MATERIAL AND METHODS

A selective literature search was carried out with analysis of dedicated original research articles and reviews as well as a discussion of the clinical guidelines.

RESULTS

Computed tomography (CT) is the basic diagnostic tool in patients with malignant lymphomas. Particularly important is fluorodeoxyglucose (FDG) positron emission tomography (PET) CT, which enables a more accurate stage definition and a better assessment of the response to treatment in FDG-avid lymphoma subtypes. Using the FDG-PET/CT-based Deauville score persisting disease activity can be identified in residual masses and refractory disease can be distinguished from complete metabolic remission. The use of magnetic resonance imaging (MRI) with diffusion-weighted imaging can represent a future alternative but is, however, not yet sufficiently standardized and validated.

CONCLUSION

The standardized analysis and reporting of purely morphological and metabolic imaging procedures is the backbone of treatment decisions in patients with malignant lymphomas.

Abdominal lymphatic system visibility, morphology, and abnormalities in children as seen on routine MCRP and its association with immune-mediated diseases

PURPOSE

(1) To assess the visibility and diameters of the thoracic duct (TD) and cisterna chyli (CC) on MR cholangiopancreatography (MRCP) in children. (2) To evaluate for the presence of any lymphatic abnormalities and assess their association with diseases in which the immune system is implicated in etiopathogenesis.

METHODS

This retrospective study included 142 MRCPs performed in children 8-17 years old and without prior surgeries. Two radiologists reviewed all exams for visibility and diameters of the TD and CC, and presence of abnormal lymphatic collaterals. TD and CC diameters in various disease processes were compared using Student's t tests. The association of collaterals with immune-mediated diseases was assessed using Fisher's exact tests.

RESULTS

The TD and CC were seen in 134/142 (93.7%) cases with mean diameter of 3.25 ± 1.07 mm and 126/142 (88.7%) cases with mean diameter of 4.55 ± 1.37 mm respectively. The mean diameter of CC was larger in patients with portal hypertension (p = 0.021). There were no significant differences in the TD and CC diameters between immune-mediated and non-immune-mediated diseases. Retroperitoneal collaterals were seen in 41/142 (28.8%) of cases and were associated with both portal hypertension (p = 0.0019) and immune-mediated diseases (p = 0.0083).

CONCLUSION

The TD and CC can be visualized in the majority of children on routine MRCP images, and CC has larger diameter in patients with portal hypertension. The association of collaterals with immune-mediated diseases supports a potential role of the lymphatic system in the etiopathogenesis of immune-mediated diseases.

KEY POINTS

• The lymphatic system has been increasingly implicated in a number of inflammatory and immune-mediated diseases. • The abdominal lymphatic system can be visualized in the majority of children above 8 years on routine MRCP images. Similar to adult studies, the cisterna chyli is significantly larger in children with portal hypertension. • Retroperitoneal lymphatic collaterals, seen in 29% children, are associated with immune-mediated diseases, which supports the potential role of the lymphatic system in the pathogenesis of immune-mediated diseases.

Lipid Drug Carriers for Cancer Therapeutics: An Insight into Lymphatic Targeting, P-gp, CYP3A4 Modulation and Bioavailability Enhancement

In the treatment of cancer, chemotherapy plays an important role though the efficacy of anti-cancer drug administered orally is limited, due to their poor solubility in physiological medium, inability to cross biological membrane, high Para-glycoprotein (P-gp) mediated drug efflux, and pre-systemic metabolism. These all factors cumulatively reduce drug exposure at the target site leading to multidrug resistance (MDR). Lipid based carriers systems has been explored to overcome solubility and permeability related issues of anti-cancer drugs. The lipid based formulations have also been reported to circumvent the effect of P-gp and CYP3A4. Further long chain triglycerides (LCT) has shown their ability to access Lymphatic route over Medium Chain Triglycerides, as the former has been extensively used for targeting anti-cancer drugs at proliferating cells through lymphatic route. Therefore this review tries to reflect the usefulness of lipid based drug carriers systems (viz. liposome, solid lipid nanoparticle, nano-lipid carriers, self-emulsifying, lipidic pro-drugs) in targeting lymphatic system and overcoming issues related to solubility and permeability of anti-cancer drugs. Moreover, we have also tried to reflect how critically lipid based carriers are important in maximizing therapeutic safety and efficacy of anti-cancer drugs.