Activation of the epidermal growth factor receptor promotes lymphangiogenesis in the skin

Contribution of initial lymphatics to oral wound healing after tooth extraction

Lymphatics are involved in the resolution of inflammation and wound healing, but their role in the oral wound healing process after tooth extraction has never been investigated. We therefore sought to evaluate the healing process following the extraction of maxillary molars in two transgenic mouse models: K14-VEGFR3-Ig mice, which lack initial mucosal lymphatic vessels, and K14-VEGFC mice, which have hyperplastic mucosal lymphatics. Maxillary molars were extracted from both transgenic mouse types and their corresponding wild-type (WT) controls. Mucosal and alveolar bone healing were evaluated. A delayed epithelialization and bone regeneration were observed in K14-VEGFR3-Ig mice compared with their WT littermates. The hampered wound closure was accompanied by decreased levels of epidermal growth factor (EGF) and persistent inflammation, characterized by infiltrates of immune cells and elevated levels of pro-inflammatory markers in the wounds. Hyperplastic mucosal lymphatics did not enhance the healing process after tooth extraction in K14-VEGFC mice. The findings indicate that initial mucosal lymphatics play a major role in the initial phase of the oral wound healing process.

Functional aspects of the brain lymphatic drainage system in aging and neurodegenerative diseases

The phenomenon of an aging population is advancing at a precipitous rate. Alzheimer's disease (AD) and Parkinson's disease (PD) are two of the most common age-associated neurodegenerative diseases, both of which are primarily characterized by the accumulation of toxic proteins and the progressive demise of neuronal structures. Recent discoveries about the brain lymphatic drainage system have precipitated a growing body of investigations substantiating its novel roles, including the clearance of macromolecular waste and the trafficking of immune cells. Notably, aquaporin 4-mediated glymphatic transport, crucial for maintaining neural homeostasis, becomes disrupted during the aging process and is further compromised in the pathogenesis of AD and PD. Functional meningeal lymphatic vessels, which facilitate the drainage of cerebrospinal fluid into the deep cervical lymph nodes, are integral in bridging the central nervous system with peripheral immune responses. Dysfunction in these meningeal lymphatic vessels exacerbates pathological trajectory of the age-related neurodegenerative disease. This review explores modulatory influence of the glymphatic system and meningeal lymphatic vessels on the aging brain and its associated neurodegenerative disorders. It also encapsulates the insights of potential mechanisms and prospects of the targeted non-pharmacological interventions.

Toward Characterizing Lymphatic Vasculature in the Mammary Gland During Normal Development and Tumor-Associated Remodeling

Lymphatic vasculature has been shown to promote metastatic spread of breast cancer. Lymphatic vasculature, which is made up of larger collecting vessels and smaller capillaries, has specialized cell junctions that facilitate cell intravasation. Normally, these junctions are designed to collect immune cells and other cellular components for immune surveillance by lymph nodes, but they are also utilized by cancer cells to facilitate metastasis. Although lymphatic development overall in the body has been well-characterized, there has been little focus on how the lymphatic network changes in the mammary gland during stages of remodeling such as pregnancy, lactation, and postpartum involution. In this review, we aim to define the currently known lymphangiogenic factors and lymphatic remodeling events during mammary gland morphogenesis. Furthermore, we juxtapose mammary gland pubertal development and postpartum involution to show similarities of pro-lymphangiogenic signaling as well as other molecular signals for epithelial cell survival that are critical in these morphogenic stages. The similar mechanisms include involvement of M2-polarized macrophages that contribute to matrix remodeling and vasculogenesis; signal transducer and activator of transcription (STAT) survival and proliferation signaling; and cyclooxygenase 2 (COX2)/Prostaglandin E2 (PGE2) signaling to promote ductal and lymphatic expansion. Investigation and characterization of lymphangiogenesis in the normal mammary gland can provide insight to targetable mechanisms for lymphangiogenesis and lymphatic spread of tumor cells in breast cancer.

Signaling mechanisms underlying lymphatic vessel dysfunction in skin aging and possible anti-aging strategies

Aging-related skin diseases are gradually increasing due to the imbalance of cutaneous homeostasis in the aging population. Skin aging-induced inflammation promotes systemic inflammation and may lead to whole-body aging. Lymphatic vessels play an important role in maintaining fluid and homeostasis balance. In intrinsically aged skin, the number of lymphatic vessels decrease and their functions decline, which is related to the reduced adhesion junctions between lymphatic endothelial cells, particularly VE-cadherin. VEGFC/VEGFR-3 signal pathway plays an important role in remodeling and expansion of lymphatic vessels; the downregulation of this pathway contributes to the dysfunction of lymphatic vessels. Meanwhile, we proposed some additional mechanisms. Decline of the pumping activity of lymphatic vessels might be related to age-related changes in extracellular matrix, ROS increase, and eNOS/iNOS disturbances. In extrinsically aged skin, the hyperpermeability of lymphatic vessels results from a decrease in endothelial-specific tight junction molecules, upregulation of VEGF-A, and downregulation of the VEGFC/VEGFR-3 signaling pathway. Furthermore, some of the Phyto therapeutics could attenuate skin aging by modulating the lymphatic vessels. This review summarized the lymphatic vessel dysfunction in skin aging and anti-aging strategies based on lymphatic vessel modulation.

A functional role of meningeal lymphatics in sex difference of stress susceptibility in mice

Major depressive disorder is one of the most common mental health conditions. Meningeal lymphatics are essential for drainage of molecules in the cerebrospinal fluid to the peripheral immune system. Their potential role in depression-like behaviour has not been investigated. Here, we show in mice, sub-chronic variable stress as a model of depression-like behaviour impairs meningeal lymphatics in females but not in males. Manipulations of meningeal lymphatics regulate the sex difference in the susceptibility to stress-induced depression- and anxiety-like behaviors in mice, as well as alterations of the medial prefrontal cortex and the ventral tegmental area, brain regions critical for emotional regulation. Together, our findings suggest meningeal lymphatic impairment contributes to susceptibility to stress in mice, and that restoration of the meningeal lymphatics might have potential for modulation of depression-like behaviour.

A Defect of Amphiregulin Release Predicted Longer Survival Independently of YAP Expression in Patients with Pleural Mesothelioma in the IFCT-0701 MAPS Phase 3 Trial

The Hippo pathway effector YAP is dysregulated in malignant pleural mesothelioma (MPM). YAP's target genes include the secreted growth factor amphiregulin (AREG), which is overexpressed in a wide range of epithelial cancers and plays an elusive role in MPM. We assayed the expression of YAP and AREG in MPM pathology samples and that of AREG additionally in plasma samples of patients from the randomized phase 3 IFCT‐0701 Mesothelioma Avastin Cisplatin Pemetrexed Study (MAPS) using immunohistochemistry and ELISA assays, respectively. MPM patients frequently presented high levels of tumor AREG (64.3%), a high cytosolic AREG expression being predictive of a better prognosis with longer median overall and progression‐free survival. Surprisingly, tumor AREG cytosolic expression was not correlated with secreted plasma AREG. By investigating the AREG metabolism and function in MPM cell lines H2452, H2052, MSTO‐211H and H28, in comparison with the T47D ER+ breast cancer cell line used as a positive control, we confirm that AREG is important for cell invasion, growth without anchorage, proliferation and apoptosis in mesothelioma cells. Yet, most of these MPM cell lines failed to correctly execute AREG posttranslational processing by metalloprotease ADAM17/tumor necrosis factor‐alpha‐converting enzyme (TACE) and extracell secretion. The favorable prognostic value of high cytosolic AREG expression in MPM patients could therefore be sustained by default AREG posttranslational processing and release. Thus, the determination of mesothelioma cell AREG content could be further investigated as a prognostic marker for MPM patients and used as a stratification factor in future clinical trials.

Advances in Lymphedema

Lymphedema is a common, complex, and inexplicably underappreciated human disease. Despite a history of relative neglect by health care providers and by governmental health care agencies, the last decade has seen an explosive growth of insights into, and approaches to, the problem of human lymphedema. The current review highlights the significant advances that have occurred in the investigative and clinical approaches to lymphedema, particularly over the last decade. This review summarizes the progress that has been attained in the realms of genetics, lymphatic imaging, and lymphatic surgery. Newer molecular insights are explored, along with their relationship to future molecular therapeutics. Growing insights into the relationships among lymphedema, obesity, and other comorbidities are important to consider in current and future responses to patients with lymphedema.

Dysregulation of Amphiregulin stimulates the pathogenesis of cystic lymphangioma

Along with blood vessels, lymphatic vessels play an important role in the circulation of body fluid and recruitment of immune cells. Postnatal lymphangiogenesis commonly occurs from preexisting lymphatic vessels by sprouting, which is induced by lymphangiogenic factors such as vascular endothelial growth factor C (VEGF-C). However, the key signals and cell types that stimulate pathological lymphangiogenesis, such as human cystic lymphangioma, are less well known. Here, we found that mouse dermal fibroblasts that infiltrate to sponges subcutaneously implanted express VEGF-D and sushi, Von Willebrand factor type A, EGF, and pentraxin domain containing 1 (SVEP1) in response to PDGFRβ signal. In vitro, Pdgfrb knockout (β-KO) fibroblasts had reduced expression of VEGF-D and SVEP1 and overproduced Amphiregulin. Dysregulation of these three factors was involved in the cyst-like and uneven distribution of lymphatic vessels observed in the β-KO mice. Similarly, in human cystic lymphangioma, which is one of the intractable diseases and mostly occurs in childhood, fibroblasts surrounding cystic lymphatics highly expressed Amphiregulin. Moreover, fibroblast-derived Amphiregulin could induce the expression of Amphiregulin in lymphatic endothelial cells. The dual source of Amphiregulin activated EGFR expressed on the lymphatic endothelial cells. This exacerbation cascade induced proliferation of lymphatic endothelial cells to form cystic lymphangioma. Ultimately, excessive Amphiregulin produced by fibroblasts surrounding lymphatics and by lymphatic endothelial cells per se results in pathogenesis of cystic lymphangioma and will be a fascinating therapeutic target of cystic lymphangioma.

Control of Gene Expression by Exosome-Derived Non-Coding RNAs in Cancer Angiogenesis and Lymphangiogenesis

Abstract: Tumour angiogenesis and lymphangiogenesis are hallmarks of cancer and have been associated with tumour progression, tumour metastasis and poor patient prognosis. Many factors regulate angiogenesis and lymphangiogenesis in cancer including non-coding RNAs which are a category of RNAs that do not encode proteins and have important regulatory functions at transcriptional and post-transcriptional levels. Non-coding RNAs can be encapsulated in extracellular vesicles called exosomes which are secreted by tumour cells or other cells in the tumour microenvironment and can then be taken up by the endothelial cells of blood vessels and lymphatic vessels. The "delivery" of these non-coding RNAs to endothelial cells in tumours can facilitate tumour angiogenesis and lymphangiogenesis. Here we review recent findings about exosomal non-coding RNAs, specifically microRNAs and long non-coding RNAs, which regulate tumour angiogenesis and lymphangiogenesis in cancer. We then focus on the potential use of these molecules as cancer biomarkers and opportunities for exploiting ncRNAs for the treatment of cancer.

Loss of Primary Cilia Protein IFT20 Dysregulates Lymphatic Vessel Patterning in Development and Inflammation

Microenvironmental signals produced during development or inflammation stimulate lymphatic endothelial cells to undergo lymphangiogenesis, in which they sprout, proliferate, and migrate to expand the vascular network. Many cell types detect changes in extracellular conditions via primary cilia, microtubule-based cellular protrusions that house specialized membrane receptors and signaling complexes. Primary cilia are critical for receipt of extracellular cues from both ligand-receptor pathways and physical forces such as fluid shear stress. Here, we report the presence of primary cilia on immortalized mouse and primary adult human dermal lymphatic endothelial cells in vitro and on both luminal and abluminal domains of mouse corneal, skin, and mesenteric lymphatic vessels in vivo. The purpose of this study was to determine the effects of disrupting primary cilia on lymphatic vessel patterning during development and inflammation. Intraflagellar transport protein 20 (IFT20) is part of the transport machinery required for ciliary assembly and function. To disrupt primary ciliary signaling, we generated global and lymphatic endothelium-specific IFT20 knockout mouse models and used immunofluorescence microscopy to quantify changes in lymphatic vessel patterning at E16.5 and in adult suture-mediated corneal lymphangiogenesis. Loss of IFT20 during development resulted in edema, increased and more variable lymphatic vessel caliber and branching, as well as red blood cell-filled lymphatics. We used a corneal suture model to determine ciliation status of lymphatic vessels during acute, recurrent, and tumor-associated inflammatory reactions and wound healing. Primary cilia were present on corneal lymphatics during all of the mechanistically distinct lymphatic patterning events of the model and assembled on lymphatic endothelial cells residing at the limbus, stalk, and vessel tip. Lymphatic-specific deletion of IFT20 cell-autonomously exacerbated acute corneal lymphangiogenesis resulting in increased lymphatic vessel density and branching. These data are the first functional studies of primary cilia on lymphatic endothelial cells and reveal a new dimension in regulation of lymphatic vascular biology.

Biomaterials for Modulating Lymphatic Function in Immunoengineering

Immunoengineering is a rapidly growing and interdisciplinary field focused on developing tools to study and understand the immune system, then employing that knowledge to modulate immune response for the treatment of disease. Because of its roles in housing a substantial fraction of the body's lymphocytes, in facilitating immune cell trafficking, and direct immune modulatory functions, among others, the lymphatic system plays multifaceted roles in immune regulation. In this review, the potential for biomaterials to be applied to regulate the lymphatic system and its functions to achieve immunomodulation and the treatment of disease are described. Three related processes-lymphangiogenesis, lymphatic vessel contraction, and lymph node remodeling-are specifically explored. The molecular regulation of each process and their roles in pathologies are briefly outlined, with putative therapeutic targets and the lymphatic remodeling that can result from disease highlighted. Applications of biomaterials that harness these pathways for the treatment of disease via immunomodulation are discussed.

Breast Cancer Systemic Treatments and Upper Limb Lymphedema: A Risk-Assessment Platform Encompassing Tumor-Specific Pathological Features Reveals the Potential Role of Trastuzumab

Breast cancer related lymphedema (BCRL) is frequent but strategies for an individualized risk assessment are lacking. We aimed to define whether tumor-specific pathological features, coupled with clinical and therapeutic data, could help identify patients at risk. Data from 368 patients with node-positive breast cancers were retrospectively collected, including 75 patients with BCRL (0.4⁻25.6 years follow-up). BCRL was assessed during the standard follow-up oncology visits using the circumferential measurement. Clinicopathologic and therapeutic factors associated with BCRL were integrated into a Cox proportional hazards regression model. Lymphovascular invasion (LVI) was more common in BCRL patients (n = 33, 44% vs. n = 85, 29%, p = 0.01), akin extra nodal extension (ENE) of the metastasis (n = 57, 76% vs. n = 180, 61%, p = 0.02). Sentinel lymph node excision without axillary dissection and extra-axillary radiotherapy were BCRL-unrelated. A higher number of BCRL-positive patients were treated with taxane-based chemotherapy with or without trastuzumab, compared to BCRL-negative patients (p < 0.01). Treatment with trastuzumab and/or taxanes, adjusted for systemic infections, laterality, therapy, and pathological features (i.e., LVI and ENE), had a significant impact in BCRL-free survival (p < 0.01). This work offers new insights on BCRL risk stratification, where the integration of clinical, therapeutic, and tumor-specific pathological data suggests a possible role of anti-human epidermal growth factor receptor 2 (HER2) therapy in BCRL pathogenesis.

Critical review: Cardiac telocytes vs cardiac lymphatic endothelial cells

The study of cardiac interstitial Cajal-like cells (ICLCs) began in 2005 and continued until 2010, when these cells were renamed as telocytes (TCs). Since then, numerous papers on cardiac ICLCs and TCs have been published. However, in the initial descriptions upon which further research was based, lymphatic endothelial cells (LECs) and initial lymphatics were not considered. No specific antibodies for LECs (such as podoplanin or LYVE-1) were used in cardiac TC studies, although ultrastructurally, LECs and TCs have similar morphological traits, including the lack of a basal lamina. When tissues are longitudinally cut, migrating LECs involved in adult lymphangiogenesis have an ICLC or TC morphology, both in light and transmission electron microscopy. In this paper, we present evidence that at least some cardiac TCs are actually LECs. Therefore, a clear-cut distinction should be made between TCs and LECs, at both the molecular and the ultrastructural levels, in order to avoid obtaining invalid data.

Simultaneous blockade of IL-6 and CCL5 signaling for synergistic inhibition of triple-negative breast cancer growth and metastasis

Background

Metastatic triple-negative breast cancer (TNBC) is a heterogeneous and incurable disease. Numerous studies have been conducted to seek molecular targets to treat TNBC effectively, but chemotherapy is still the main choice for patients with TNBC. We have previously presented evidence of the important roles of interleukin-6 (IL-6) and chemokine (C-C motif) ligand 5 (CCL5) in TNBC tumor growth and metastasis. These experiments highlighted the importance of the crosstalk between cancer cells and stromal lymphatic endothelial cells (LECs) in tumor growth and metastasis.

Methods

We examined the viability and migration of MDA-MB-231-LN, SUM149, and SUM159 cells co-cultured with LECs when treated with maraviroc (CCR5 inhibitor) and tocilizumab (anti-IL-6 receptor antibody). To assess the anti-tumor effects of the combination of these two drugs in an athymic nude mouse model, MDA-MB-231-LN cells were implanted in the mammary fat pad and maraviroc (8 mg/kg, orally daily) and cMR16-1 (murine surrogate of the anti-IL-6R antibody, 10 mg/kg, IP, 3 days a week) were administrated for 5 weeks and effects on tumor growth and thoracic metastasis were measured.

Results

In this study, we used maraviroc and tocilizumab to confirm that IL-6 and CCL5 signaling are key pathways promoting TNBC cell proliferation and migration. Further, in a xenograft mouse model, we showed that tumor growth was dramatically inhibited by cMR16-1, the mouse version of the anti-IL6R antibody. The combination of maraviroc and cMR16-1 caused significant reduction of TNBC tumor growth compared to the single agents. Significantly, the combination of maraviroc and cMR16-1 abrogated thoracic metastasis.

Conclusion

Taken together, these findings show that IL-6 and CCL5 signaling, which promote crosstalk between TNBC and lymphatic vessels, are key enhancers of TNBC tumor growth and metastasis. Furthermore, these results demonstrate that a drug combination inhibiting these pathways may be a promising therapy for TNBC patients.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0981-3) contains supplementary material, which is available to authorized users.

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

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

Multipotent Adult Progenitor Cells Support Lymphatic Regeneration at Multiple Anatomical Levels during Wound Healing and Lymphedema

Lymphatic capillary growth is an integral part of wound healing, yet, the combined effectiveness of stem/progenitor cells on lymphatic and blood vascular regeneration in wounds needs further exploration. Stem/progenitor cell transplantation also emerged as an approach to cure lymphedema, a condition caused by lymphatic system deficiency. While lymphedema treatment requires lymphatic system restoration from the capillary to the collector level, it remains undetermined whether stem/progenitor cells support a complex regenerative response across the entire anatomical spectrum of the system. Here, we demonstrate that, although multipotent adult progenitor cells (MAPCs) showed potential to differentiate down the lymphatic endothelial lineage, they mainly trophically supported lymphatic endothelial cell behaviour in vitro. In vivo, MAPC transplantation supported blood vessel and lymphatic capillary growth in wounds and restored lymph drainage across skin flaps by stimulating capillary and pre-collector vessel regeneration. Finally, human MAPCs mediated survival and functional reconnection of transplanted lymph nodes to the host lymphatic network by improving their (lymph)vascular supply and restoring collector vessels. Thus, MAPC transplantation represents a promising remedy for lymphatic system restoration at different anatomical levels and hence an appealing treatment for lymphedema. Furthermore, its combined efficacy on lymphatic and blood vascular growth is an important asset for wound healing.

Lymphangiogenesis guidance by paracrine and pericellular factors

This review by Vaahtomeri et al. discusses the mechanisms by which the lymphatic vasculature network is formed, remodeled, and adapted to physiological and pathological challenges. It describes how the lymphatic vasculature network is controlled by an intricate balance of growth factors and biomechanical cues.

Lymphatic vessels are important for tissue fluid homeostasis, lipid absorption, and immune cell trafficking and are involved in the pathogenesis of several human diseases. The mechanisms by which the lymphatic vasculature network is formed, remodeled, and adapted to physiological and pathological challenges are controlled by an intricate balance of growth factor and biomechanical cues. These transduce signals for the readjustment of gene expression and lymphatic endothelial migration, proliferation, and differentiation. In this review, we describe several of these cues and how they are integrated for the generation of functional lymphatic vessel networks.

Combined targeting of TGF-β, EGFR and HER2 suppresses lymphangiogenesis and metastasis in a pancreatic cancer model

Pancreatic ductal adenocarcinomas (PDACs) are aggressive with frequent lymphatic spread. By analysis of data from The Cancer Genome Atlas, we determined that ~35% of PDACs have a pro-angiogenic gene signature. We now show that the same PDACs exhibit increased expression of lymphangiogenic genes and lymphatic endothelial cell (LEC) markers, and that LEC abundance in human PDACs correlates with endothelial cell microvessel density. Lymphangiogenic genes and LECs are also elevated in murine PDACs arising in the KRC (mutated Kras; deleted RB) and KIC (mutated Kras; deleted INK4a) genetic models. Moreover, pancreatic cancer cells (PCCs) derived from KRC tumors express and secrete high levels of lymphangiogenic factors, including the EGF receptor ligand, amphiregulin. Importantly, TGF-β1 increases lymphangiogenic genes and amphiregulin expression in KRC PCCs but not in murine PCCs that lack SMAD4, and combinatorial targeting of the TGF-β type I receptor (TβRI) with LY2157299 and EGFR/HER2 with lapatinib suppresses tumor growth and metastasis in a syngeneic orthotopic model, and attenuates tumor lymphangiogenesis and angiogenesis while reducing lymphangiogenic genes and amphiregulin and enhancing apoptosis. Therefore, this combination could be beneficial in PDACs with lymphangiogenic or angiogenic gene signatures.

Tumor lymphangiogenesis and new drug development

Traditionally, tumor-associated lymphatic vessels have been regarded as passive by-standers, serving simply as a drainage system for interstitial fluid generated within the tumor. However, with growing evidence that tumors actively induce lymphangiogenesis, and that the number of lymphatic vessels closely correlates with metastasis and clinical outcome in various types of cancer, this picture has changed dramatically in recent years. Tumor-associated lymphatic vessels have now emerged as a valid therapeutic target to control metastatic disease, and the first specific anti-lymphangiogenic drugs have recently entered clinical testing. Furthermore, we are just beginning to understand the whole functional spectrum of tumor-associated lymphatic vessels, which not only concerns transport of fluid and metastatic cells, but also includes the regulation of cancer stemness and specific inhibition of immune responses, opening new venues for therapeutic applications. Therefore, we predict that specific targeting of lymphatic vessels and their function will become an important tool for future cancer treatment.

Hypoxic conditioned medium from mesenchymal stem cells promotes lymphangiogenesis by regulation of mitochondrial-related proteins

BACKGROUND

Recently, cell-based therapeutic lymphangiogenesis has emerged and provided hope for lymphatic regeneration. Previous studies have demonstrated that secretomes of mesenchymal stem cells (MSCs) facilitate the regeneration of various damaged tissues. This study was conducted to evaluate the lymphangiogenic potential of hypoxic conditioned media (HCM) from MSCs.

METHODS

To investigate the effects of MSC-secreted factors in starved human lymphatic endothelial cells (hLEC), hLECs were treated with endothelial basal medium (EBM)-2 (control), normoxic conditioned media (NCM), or HCM in vitro and in vivo.

RESULTS

MSCs expressed lymphangiogenic factors including EGF, FGF2, HGF, IGF-1, and VEGF-A and -C. hLECs were treated with each medium. hLEC proliferation, migration, and tube formation were improved under HCM compared with NCM. Moreover, expression of mitochondrial-related factors, MFN1and 2, were improved in HCM-treated hLECs. Lymphedema mice injected with HCM showed markedly decreased lymphedema via increased lymphatic vessel formation when compared with EBM-2- or NCM-treated mice.

CONCLUSIONS

This study suggested that HCM from MSCs contain high levels of secreted lymphangiogenic factors and promote lymphangiogenesis by regulating mitochondrial-related factors. Thus, treatment with HCM may be a therapeutic strategy for lymphedema.

Anti-EGFR antibody reduces lung nodules by inhibition of EGFR-pathway in a model of lymphangioleiomyomatosis

EGFR belongs to the HER/ErbB family of tyrosine kinase receptors and its activation in cancer cells has been linked with increased proliferation, angiogenesis, and metastasis. Lymphangioleiomyomatosis (LAM) is a rare, low-grade neoplasm that occurs sporadically or in association with tuberous sclerosis complex (TSC), a genetic, multisystem disorder characterized by hamartomas in several organs. From chylous of a LAM/TSC patient, we previously isolated smooth muscle-like LAM/TSC cells whose proliferation depends on EGF and monoclonal anti-EGFR antibodies reduced proliferation and caused cell death. We demonstrated that the dependency from EGF was caused by the absence of tuberin. To study the role of EGFR pathway in vivo, we developed a mouse model by administration of LAM/TSC cells to female nude mice. LAM/TSC cells caused pulmonary airspace enlargement and, after 30 weeks, nodule formation which express EGFR. Anti-EGFR antibody decreased the number and dimension of lung nodules likely for the inhibition of Erk and S6 signaling, reversed the pulmonary alterations, and reduced lymphatic and blood vessels. Moreover, in pulmonary nodules anti-EGFR antibody reduced the positivity to estrogen and progesterone receptors which enhance survival of LAM cells and Snail expression. These results suggest that the inhibition of EGFR signalling has a potential in treatment of LAM/TSC lung alterations.

Cell-based therapy for therapeutic lymphangiogenesis

Lymphedema is a medically irreversible condition for which currently conservative and surgical therapies are either ineffective or impractical. The potential use of progenitor and stem cell-based therapies has offered a paradigm that may provide alternative treatment options for lymphatic disorders. Moreover, basic research, preclinical studies, as well as clinical trials have evaluated the therapeutic potential of various cell therapies in the field of lymphatic regeneration medicine. Among the available cell approaches, mesenchymal stem cells (MSCs) seem to be the most promising candidate mainly due to their abundant sources and easy availability as well as evitable ethical and immunological issues confronted with embryonic stem cells and induced pluripotent stem cells. In this context, the purpose of this review is to summarize various cell-based therapies for lymphedema, along with strengths and weaknesses of these therapies in the clinical application for lymphedema treatment. Particularly, we will highlight the use of MSCs for lymphatic regeneration medicine. In addition, the future perspectives of MSCs in the field of lymphatic regeneration will be discussed.

Lymphangiogenesis in renal diseases: passive bystander or active participant?

Lymphatic vessels (LVs) are involved in a number of physiological and pathophysiological processes such as fluid homoeostasis, immune surveillance, and resolution of inflammation and wound healing. Lymphangiogenesis, the outgrowth of existing LVs and the formation of new ones, has received increasing attention over the past decade on account of its prominence in organ physiology and pathology, which has been enabled by the development of specific tools to study lymph vessel functions. Several studies have been devoted to renal lymphatic vasculature and lymphangiogenesis in kidney diseases, such as chronic renal transplant dysfunction, primary renal fibrotic disorders, proteinuria, diabetic nephropathy and renal inflammation. This review describes the most recent findings on lymphangiogenesis, with a specific focus on renal lymphangiogenesis and its impact on renal diseases. We suggest renal lymphatics as a possible target for therapeutic interventions in renal medicine to dampen tubulointerstitial tissue remodelling and improve renal functioning.

Bone marrow-derived mesenchymal stem cells drive lymphangiogenesis

It is now well accepted that multipotent Bone-Marrow Mesenchymal Stem Cells (BM-MSC) contribute to cancer progression through several mechanisms including angiogenesis. However, their involvement during the lymphangiogenic process is poorly described. Using BM-MSC isolated from mice of two different backgrounds, we demonstrate a paracrine lymphangiogenic action of BM-MSC both in vivo and in vitro. Co-injection of BM-MSC and tumor cells in mice increased the in vivo tumor growth and intratumoral lymphatic vessel density. In addition, BM-MSC or their conditioned medium stimulated the recruitment of lymphatic vessels in vivo in an ear sponge assay, and ex vivo in the lymphatic ring assay (LRA). In vitro, MSC conditioned medium also increased the proliferation rate and the migration of both primary lymphatic endothelial cells (LEC) and an immortalized lymphatic endothelial cell line. Mechanistically, these pro-lymphangiogenic effects relied on the secretion of Vascular Endothelial Growth Factor (VEGF)-A by BM-MSC that activates VEGF Receptor (VEGFR)-2 pathway on LEC. Indeed, the trapping of VEGF-A in MSC conditioned medium by soluble VEGF Receptors (sVEGFR)-1, -2 or the inhibition of VEGFR-2 activity by a specific inhibitor (ZM 323881) both decreased LEC proliferation, migration and the phosphorylation of their main downstream target ERK1/2. This study provides direct unprecedented evidence for a paracrine lymphangiogenic action of BM-MSC via the production of VEGF-A which acts on LEC VEGFR-2.

The use of pH-sensitive functional selenium nanoparticles shows enhanced in vivo VEGF-siRNA silencing and fluorescence imaging

The utility of small interfering RNAs (siRNAs) has shown great promise in treating a variety of diseases including many types of cancer. While their ability to silence a wide range of target genes underlies their effectiveness, the application of therapies remains hindered by a lack of an effective delivery system. In this study, we sought to develop an siRNA-delivery system for VEGF, a known signaling molecule involved in cancer, that consists of two selenium nanoparticles SeNPs and G2/PAH-Cit/SeNPs. A G2/PAH-Cit/SeNP is a pH-sensitive delivery system that is capable of enhancing siRNA loading, thus increasing siRNA release efficiency and subsequent target gene silencing both in vitro and in vivo. In vivo experiments using G2/PAH-Cit/SeNPs@siRNA led to significantly higher accumulation of siRNA within the tumor itself, VEGF gene silencing, and reduced angiogenesis in the tumor. Furthermore, the G2/PAH-Cit/SeNP delivery system not only enhanced anti-tumor effects on tumor-bearing nude mice as compared to SeNPs@siRNA, but also resulted in weak occurrence of lesions in major target organs. In sum, this study provides a new class of siRNA delivery system, thereby providing an alternative therapeutic route for cancer treatment.

Lung mesenchymal expression of Sox9 plays a critical role in tracheal development

Background

Embryonic lung development is instructed by crosstalk between mesenchyme and epithelia, which results in activation of transcriptional factors, such as Sox9, in a temporospatial manner. Sox9 is expressed in both distal lung epithelium and proximal lung mesenchyme. Here, we investigated the effect of lung mesenchyme-specific inducible deletion of Sox9 during murine lung development.

Results

Transgenic mice lacking Sox9 expression were unable to breathe and died at birth, with noticeable tracheal defects. Cartilage rings were missing, and the tracheal lumen was collapsed in the mutant trachea. In situ hybridization showed an altered expression pattern of Tbx4, Tbx5 and Fgf10 genes and marked reduction of Collagen2 expression in the tracheal mesenchyme. The tracheal phenotype was increasingly severe, with longer duration of deletion. Lymphatic vasculature was underdeveloped in the mutant trachea: Prox1, Lyve1, and Vegfr3 were decreased after Sox9 knockout. We also found that compared with normal tracheal epithelium, the mutant tracheal epithelium had an altered morphology with fewer P63-positive cells and more CC10-positive cells, fewer goblet cells, and downregulation of surfactant proteins A and C.

Conclusion

The appropriate temporospatial expression of Sox9 in lung mesenchyme is necessary for appropriate tracheal cartilage formation, lymphatic vasculature system development, and epithelial differentiation. We uncovered a novel mechanism of lung epithelium differentiation: tracheal cartilage rings instruct the tracheal epithelium to differentiate properly during embryonic development. Thus, besides having a mechanical function, tracheal cartilage also appears to be a local signaling structure in the embryonic lung.