Vascular Endothelial Growth Factor-C Treatment Enhances Cerebrospinal Fluid Outflow during Toxoplasma gondii Brain Infection but Does Not Improve Cerebral Edema.

Cerebral edema frequently develops in the setting of brain infection and can contribute to elevated intracranial pressure, a medical emergency. How excess fluid is cleared from the brain is not well understood. Previous studies have shown that interstitial fluid is transported out of the brain along perivascular channels that collect into the cerebrospinal fluid (CSF)-filled subarachnoid space. CSF is then removed from the central nervous system through venous and lymphatic routes. The current study tested the hypothesis that increasing lymphatic drainage of CSF would promote clearance of cerebral edema fluid during infection with the neurotropic parasite Toxoplasma gondii. Fluorescent microscopy and magnetic resonance imaging was used to show that C57BL/6 mice develop vasogenic edema 4 to 5 weeks after infection with T. gondii. Tracer experiments were used to evaluate how brain infection affects meningeal lymphatic function, which demonstrated a decreased rate in CSF outflow in T. gondii-infected mice. Next, mice were treated with a vascular endothelial growth factor (VEGF)-C-expressing viral vector, which induced meningeal lymphangiogenesis and improved CSF outflow in chronically infected mice. No difference in cerebral edema was observed between mice that received VEGF-C and those that rececived sham treatment. Therefore, although VEGF-C treatment can improve lymphatic outflow in mice infected with T. gondii, this effect does not lead to increased clearance of edema fluid from the brains of these mice.

FLT4 as a marker for predicting prognostic risk of refractory acute myeloid leukemia.

Treating patients with refractory acute myeloid leukemia (AML) remains challenging. Currently there is no effective treatment for refractory AML. Increasing evidence has demonstrated that refractory/relapsed AML is associated with leukemic blasts which can confer resistance to anticancer drugs. We have previously reported that high expression of Fms-related tyrosine kinase 4 (FLT4) is associated with increased cancer activity in AML. However, the functional role of FLT4 in leukemic blasts remains unknown. Here, we explored the significance of FLT4 expression in leukemic blasts of refractory patients and mechanisms involved in the survival of AML blasts. Inhibition or absence of FLT4 in AML blasts suppressed homing to bone marrow of immunocompromised mice and blocked engraftment of AML blasts. Moreover, FLT4 inhibition by MAZ51, an antagonist, effectively reduced the number of leukemic cell-derived colony-forming units and increased apoptosis of blasts derived from refractory patients when it was co-treated with cytosine arabinoside under vascular endothelial growth factor C, its ligand. AML patients who expressed high cytosolic FLT4 were linked to an AML-refractory status by internalization mechanism. In conclusion, FLT4 has a biological function in leukemogenesis and refractoriness. This novel insight will be useful for targeted therapy and prognostic stratification of AML.

A Randomized Controlled Trial of OPT-302, a VEGF-C/D Inhibitor for Neovascular Age-Related Macular Degeneration.

PURPOSE: Neovascular (wet) age-related macular degeneration (nAMD) is driven by VEGFs A, C, and D, which promote angiogenesis and vascular permeability. Intravitreal injections of anti-VEGF-A drugs are the standard of care, but these do not inhibit VEGF-C and D, which may explain why many patients fail to respond fully. This trial aimed to test the safety and efficacy of OPT-302, a biologic inhibitor of VEGF-C and D, in combination with the anti-VEGF-A inhibitor ranibizumab. DESIGN: Dose-ranging, phase 2b, randomized, double-masked, sham-controlled trial. PARTICIPANTS: Participants with treatment-naive nAMD were enrolled from 109 sites across Europe, Israel, and the United States. METHODS: Participants were randomized to 6, 4-weekly, intravitreal injections of 0.5 mg OPT-302, 2.0 mg OPT-302, or sham, plus intravitreal 0.5 mg ranibizumab. MAIN OUTCOME MEASURES: The primary outcome was mean change in ETDRS best-corrected visual acuity (BCVA) at 24 weeks. Secondary outcomes (comparing baseline with week 24) were the proportion of participants gaining or losing ≥ 15 ETDRS BCVA letters; area under the ETDRS BCVA over time curve; change in spectral-domain OCT (SD-OCT) central subfield thickness; and change in intraretinal fluid and subretinal fluid on SD-OCT. RESULTS: Of 366 participants recruited from December 1, 2017, to November 30, 2018, 122, 123, and 121 were randomized to 0.5 mg OPT-302, 2.0 mg OPT-302, and sham, respectively. Mean (± standard deviation) visual acuity gain in the 2.0 mg OPT-302 group was significantly superior to sham (+14.2 ± 11.61 vs. +10.8 ± 11.52 letters; P = 0.01). The 0.5 mg OPT-302 group was not significantly different than the sham group (+9.44 ± 11.32 letters; P = 0.83). Compared with sham, the secondary BCVA outcomes favored the 2.0 mg OPT-302 group, with structural outcomes favoring both OPT-302 dosage groups. Adverse events (AEs) were similar across groups, with 16 (13.3%), 7 (5.6%), and 10 (8.3%) participants in the lower-dose, higher-dose, and sham groups, respectively, developing at least 1 serious AE. Two unrelated deaths both occurred in the sham arm. CONCLUSIONS: Significantly superior vision gain was observed with OPT-302 2.0 mg combination therapy, versus standard of care, with favorable safety (ClinicalTrials.gov identifier: NCT03345082). FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Plasminogen activating inhibitor-1 promotes angiogenesis in cutaneous angiosarcomas.

Plasminogen activating inhibitor-1 (PAI-1) is associated with poor clinical outcomes, and elevated levels of PAI-1 in both tissue and serum are correlated with poor response to therapy in various cancers, including skin cancer. Cutaneous angiosarcoma (CAS) is a vascular tumor histologically characterized by detachment of endothelial cell-derived tumor cells. Since CAS expresses multiple angiogenic growth factors and has increased expressions of angiogenic receptor tyrosine kinase transcripts including VEGFR1/2/3, angiogenesis-promoting factors are potential drug targets in CAS. In this study, the expression of PAI-1 was examined in 31 cases of CAS, and the immunomodulatory effects of PAI-1 on a human CAS cell line, ISO-HAS-B, were evaluated. We found that, of the angiogenesis-promoting factors, PAI-1 was expressed in almost all cases of CAS, and PAI-1 increased the mRNA expressions of IL-23p19, VEGF-C, CXCL5 and CCL20 on ISO-HAS-B. Moreover, PAI-1 stimulated ISO-HAS-B culture supernatant promoted favourable tube networks, suggesting that these tumor-derived factors promote the pro-angiogenic effect on tumor development. In addition, IL-23p19 was expressed in 61.3% of cases, whereas VEGF-C was expressed in 41% of cases. The results of the present study suggest that PAI-1 promotes angiogenesis that results in tumor progression in CAS.

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

BACKGROUND: Dysfunction of the lymphatic system following injury, disease, or cancer treatment can lead to lymphedema, a debilitating condition with no cure. Despite the various physical therapy and surgical options available, most treatments are palliative and fail to address the underlying lymphatic vascular insufficiency driving lymphedema progression. Stem cell therapy provides a promising alternative in the treatment of various chronic diseases with a wide range of therapeutic effects that reduce inflammation, fibrosis, and oxidative stress, while promoting lymphatic vessel (LV) regeneration. Specifically, stem cell transplantation is suggested to promote LV restoration, rebuild lymphatic circulation, and thus potentially be utilized towards an effective lymphedema treatment. In addition to stem cells, studies have proposed the administration of vascular endothelial growth factor C (VEGFC) to promote lymphangiogenesis and decrease swelling in lymphedema. AIMS: Here, we seek to combine the benefits of stem cell therapy, which provides a cellular therapeutic approach that can respond to the tissue environment, and VEGFC administration to restore lymphatic drainage. MATERIALS & METHODS: Specifically, we engineered mesenchymal stem cells (MSCs) to overexpress VEGFC using a lentiviral vector (hVEGFC MSC) and investigated their therapeutic efficacy in improving LV function and tissue swelling using near infrared (NIR) imaging, and lymphatic regeneration in a single LV ligation mouse tail lymphedema model. RESULTS: First, we showed that overexpression of VEGFC using lentiviral transduction led to an increase in VEGFC protein synthesis in vitro. Then, we demonstrated hVEGFC MSC administration post-injury significantly increased the lymphatic contraction frequency 14-, 21-, and 28-days post-surgery compared to the control animals (MSC administration) in vivo, while also reducing tail swelling 28-days post-surgery compared to controls. CONCLUSION: Our results suggest a therapeutic potential of hVEGFC MSC in alleviating the lymphatic dysfunction observed during lymphedema progression after secondary injury and could provide a promising approach to enhancing autologous cell therapy for treating lymphedema.

Dynamic biomarker and imaging changes from a phase II study of pre- and post-surgical sunitinib.

OBJECTIVE: To explore translational biological and imaging biomarkers for sunitinib treatment before and after debulking nephrectomy in the NeoSun (European Union Drug Regulating Authorities Clinical Trials Database [EudraCT] number: 2005-004502-82) single-centre, single-arm, single-agent, Phase II trial. PATIENTS AND METHODS: Treatment-naïve patients with metastatic renal cell carcinoma (mRCC) received 50 mg once daily sunitinib for 12 days pre-surgically, then post-surgery on 4 week-on, 2 week-off, repeating 6-week cycles until disease progression in a single arm phase II trial. Structural and dynamic contrast-enhanced magnet resonance imaging (DCE-MRI) and research blood sampling were performed at baseline and after 12 days. Computed tomography imaging was performed at baseline and post-surgery then every two cycles. The primary endpoint was objective response rate (Response Evaluation Criteria In Solid Tumors [RECIST]) excluding the resected kidney. Secondary endpoints included changes in DCE-MRI of the tumour following pre-surgery sunitinib, overall survival (OS), progression-free survival (PFS), response duration, surgical morbidity/mortality, and toxicity. Translational and imaging endpoints were exploratory. RESULTS: A total of 14 patients received pre-surgery sunitinib, 71% (10/14) took the planned 12 doses. All underwent nephrectomy, and 13 recommenced sunitinib postoperatively. In all, 58.3% (seven of 12) of patients achieved partial or complete response (PR or CR) (95% confidence interval 27.7-84.8%). The median OS was 33.7 months and median PFS was 15.7 months. Amongst those achieving a PR or CR, the median response duration was 8.7 months. No unexpected surgical complications, sunitinib-related toxicities, or surgical delays occurred. Within the translational endpoints, pre-surgical sunitinib significantly increased necrosis, and reduced cluster of differentiation-31 (CD31), Ki67, circulating vascular endothelial growth factor-C (VEGF-C), and transfer constant (KTrans , measured using DCE-MRI; all P < 0.05). There was a trend for improved OS in patients with high baseline plasma VEGF-C expression (P = 0.02). Reduction in radiological tumour volume after pre-surgical sunitinib correlated with high percentage of solid tumour components at baseline (Spearman's coefficient ρ = 0.69, P = 0.02). Conversely, the percentage tumour volume reduction correlated with lower baseline percentage necrosis (coefficient = -0.51, P = 0.03). CONCLUSION: Neoadjuvant studies such as the NeoSun can safely and effectively explore translational biological and imaging endpoints.

Meningeal lymphatic dysfunction exacerbates traumatic brain injury pathogenesis.

Traumatic brain injury (TBI) is a leading global cause of death and disability. Here we demonstrate in an experimental mouse model of TBI that mild forms of brain trauma cause severe deficits in meningeal lymphatic drainage that begin within hours and last out to at least one month post-injury. To investigate a mechanism underlying impaired lymphatic function in TBI, we examined how increased intracranial pressure (ICP) influences the meningeal lymphatics. We demonstrate that increased ICP can contribute to meningeal lymphatic dysfunction. Moreover, we show that pre-existing lymphatic dysfunction before TBI leads to increased neuroinflammation and negative cognitive outcomes. Finally, we report that rejuvenation of meningeal lymphatic drainage function in aged mice can ameliorate TBI-induced gliosis. These findings provide insights into both the causes and consequences of meningeal lymphatic dysfunction in TBI and suggest that therapeutics targeting the meningeal lymphatic system may offer strategies to treat TBI.

VEGF-C-driven lymphatic drainage enables immunosurveillance of brain tumours.

Immune surveillance against pathogens and tumours in the central nervous system is thought to be limited owing to the lack of lymphatic drainage. However, the characterization of the meningeal lymphatic network has shed light on previously unappreciated ways that an immune response can be elicited to antigens that are expressed in the brain1-3. Despite progress in our understanding of the development and structure of the meningeal lymphatic system, the contribution of this network in evoking a protective antigen-specific immune response in the brain remains unclear. Here, using a mouse model of glioblastoma, we show that the meningeal lymphatic vasculature can be manipulated to mount better immune responses against brain tumours. The immunity that is mediated by CD8 T cells to the glioblastoma antigen is very limited when the tumour is confined to the central nervous system, resulting in uncontrolled tumour growth. However, ectopic expression of vascular endothelial growth factor C (VEGF-C) promotes enhanced priming of CD8 T cells in the draining deep cervical lymph nodes, migration of CD8 T cells into the tumour, rapid clearance of the glioblastoma and a long-lasting antitumour memory response. Furthermore, transfection of an mRNA construct that expresses VEGF-C works synergistically with checkpoint blockade therapy to eradicate existing glioblastoma. These results reveal the capacity of VEGF-C to promote immune surveillance of tumours, and suggest a new therapeutic approach to treat brain tumours.

Enhancement of cardiac lymphangiogenesis by transplantation of CD34+VEGFR-3+ endothelial progenitor cells and sustained release of VEGF-C.

Impairment of cardiac lymphatic vessels leads to cardiac lymphedema. Recent studies have suggested that stimulation of lymphangiogenesis may reduce cardiac lymphedema. However, effects of lymphatic endothelial progenitor cells (LEPCs) on cardiac lymphangiogenesis are poorly understood. Therefore, this study investigated effectiveness of LEPC transplantation and VEGF-C release with self-assembling peptide (SAP) on cardiac lymphangiogenesis after myocardial infarction (MI). CD34+VEGFR-3+ EPCs isolated from rat bone marrow differentiated into lymphatic endothelial cells after VEGF-C induction. VEGF-C also stimulated the cells to incorporate into the lymphatic capillary-like structures. The functionalized SAP could adhere with the cells and released VEGF-C sustainedly. In the condition of hypoxia and serum deprivation or abdominal pouch assay, the SAP hydrogel protected the cells from apoptosis and necrosis. At 4 weeks after intramyocardial transplantation of the cells and VEGF-C loaded with SAP hydrogel in rat MI models, cardiac lymphangiogenesis was increased, cardiac edema and reverse remodeling were reduced, and cardiac function was improved significantly. Delivery with SAP hydrogel favored survival of the engrafted cells. VEGF-C released from the hydrogel promoted differentiation and incorporation of the cells as well as growth of pre-existed lymphatic vessels. Cardiac lymphangiogenesis was beneficial for elimination of the inflammatory cells in the infarcted myocardium. Moreover, angiogenesis and myocardial regeneration were enhanced after reduction of lymphedema. These results demonstrate that the combined delivery of LEPCs and VEGF-C with the functionalized SAP promotes cardiac lymphangiogenesis and repair of the infarcted myocardium effectively. This study represents a novel therapy for relieving myocardial edema in cardiovascular diseases.

Lymphedema: Pathogenesis and Novel Therapies.

Lymphedema affects up to 1 in 6 patients who undergo treatment for a solid tumor in the United States. Its prevalence has increased as more effective oncologic therapies have improved patient survival, but there remains no definitive cure. Recent research has elucidated new details in the pathogenesis of the disease and has demonstrated that it is fundamentally an immunologic process that ultimately results in inflammation, fibroadipose deposition, impaired lymphangiogenesis, and dysfunctional lymphatic pumping. These findings have allowed for the development of novel medical and surgical therapies that may potentially alter the standard of care for a disease that has largely been treated by compression. This review seeks to provide an overview of the emerging therapies and how they can be utilized for effective management of lymphedema.

Local induction of lymphangiogenesis with engineered fibrin-binding VEGF-C promotes wound healing by increasing immune cell trafficking and matrix remodeling.

Lymphangiogenesis occurs in inflammation and wound healing, yet its functional roles in these processes are not fully understood. Consequently, clinically relevant strategies for therapeutic lymphangiogenesis remain underdeveloped, particularly using growth factors. To achieve controlled, local capillary lymphangiogenesis with protein engineering and determine its effects on fluid clearance, leukocyte trafficking, and wound healing, we developed a fibrin-binding variant of vascular endothelial growth factor C (FB-VEGF-C) that is slowly released upon demand from infiltrating cells. Using a novel wound healing model, we show that implanted fibrin containing FB-VEGF-C, but not free VEGF-C, could stimulate local lymphangiogenesis in a dose-dependent manner. Importantly, the effects of FB-VEGF-C were restricted to lymphatic capillaries, with no apparent changes to blood vessels and downstream collecting vessels. Leukocyte intravasation and trafficking to lymph nodes were increased in hyperplastic lymphatics, while fluid clearance was maintained at physiological levels. In diabetic wounds, FB-VEGF-C-induced lymphangiogenesis increased extracellular matrix deposition and granulation tissue thickening, indicators of improved wound healing. Together, these results indicate that FB-VEGF-C is a promising strategy for inducing lymphangiogenesis locally, and that such lymphangiogenesis can promote wound healing by enhancing leukocyte trafficking without affecting downstream lymphatic collecting vessels.

Aligned nanofibrillar collagen scaffolds - Guiding lymphangiogenesis for treatment of acquired lymphedema.

Secondary lymphedema is a common disorder associated with acquired functional impairment of the lymphatic system. The goal of this study was to evaluate the therapeutic efficacy of aligned nanofibrillar collagen scaffolds (BioBridge) positioned across the area of lymphatic obstruction in guiding lymphatic regeneration. In a porcine model of acquired lymphedema, animals were treated with BioBridge scaffolds, alone or in conjunction with autologous lymph node transfer as a source of endogenous lymphatic growth factor. They were compared with a surgical control group and a second control group in which the implanted BioBridge was supplemented with exogenous vascular endothelial growth factor-C (VEGF-C). Three months after implantation, immunofluorescence staining of lymphatic vessels demonstrated a significant increase in lymphatic collectors within close proximity to the scaffolds. To quantify the functional impact of scaffold implantation, bioimpedance was used as an early indicator of extracellular fluid accumulation. In comparison to the levels prior to implantation, the bioimpedance ratio was significantly improved only in the experimental BioBridge recipients with or without lymph node transfer, suggesting restoration of functional lymphatic drainage. These results further correlated with quantifiable lymphatic collectors, as visualized by contrast-enhanced computed tomography. They demonstrate the therapeutic potential of BioBridge scaffolds in secondary lymphedema.

Selective Stimulation of Cardiac Lymphangiogenesis Reduces Myocardial Edema and Fibrosis Leading to Improved Cardiac Function Following Myocardial Infarction.

BACKGROUND: The lymphatic system regulates interstitial tissue fluid balance, and lymphatic malfunction causes edema. The heart has an extensive lymphatic network displaying a dynamic range of lymph flow in physiology. Myocardial edema occurs in many cardiovascular diseases, eg, myocardial infarction (MI) and chronic heart failure, suggesting that cardiac lymphatic transport may be insufficient in pathology. Here, we investigate in rats the impact of MI and subsequent chronic heart failure on the cardiac lymphatic network. Further, we evaluate for the first time the functional effects of selective therapeutic stimulation of cardiac lymphangiogenesis post-MI. METHODS AND RESULTS: We investigated cardiac lymphatic structure and function in rats with MI induced by either temporary occlusion (n=160) or permanent ligation (n=100) of the left coronary artery. Although MI induced robust, intramyocardial capillary lymphangiogenesis, adverse remodeling of epicardial precollector and collector lymphatics occurred, leading to reduced cardiac lymphatic transport capacity. Consequently, myocardial edema persisted for several months post-MI, extending from the infarct to noninfarcted myocardium. Intramyocardial-targeted delivery of the vascular endothelial growth factor receptor 3-selective designer protein VEGF-CC152S, using albumin-alginate microparticles, accelerated cardiac lymphangiogenesis in a dose-dependent manner and limited precollector remodeling post-MI. As a result, myocardial fluid balance was improved, and cardiac inflammation, fibrosis, and dysfunction were attenuated. CONCLUSIONS: We show that, despite the endogenous cardiac lymphangiogenic response post-MI, the remodeling and dysfunction of collecting ducts contribute to the development of chronic myocardial edema and inflammation-aggravating cardiac fibrosis and dysfunction. Moreover, our data reveal that therapeutic lymphangiogenesis may be a promising new approach for the treatment of cardiovascular diseases.

Vascular Endothelial Growth Factor C for Polycystic Kidney Diseases.

Polycystic kidney diseases (PKD) are genetic disorders characterized by progressive epithelial cyst growth leading to destruction of normally functioning renal tissue. Current therapies have focused on the cyst epithelium, and little is known about how the blood and lymphatic microvasculature modulates cystogenesis. Hypomorphic Pkd1(nl/nl) mice were examined, showing that cystogenesis was associated with a disorganized pericystic network of vessels expressing platelet/endothelial cell adhesion molecule 1 and vascular endothelial growth factor receptor 3 (VEGFR3). The major ligand for VEGFR3 is VEGFC, and there were lower levels of Vegfc mRNA within the kidneys during the early stages of cystogenesis in 7-day-old Pkd1(nl/nl) mice. Seven-day-old mice were treated with exogenous VEGFC for 2 weeks on the premise that this would remodel both the VEGFR3(+) pericystic vascular network and larger renal lymphatics that may also affect the severity of PKD. Treatment with VEGFC enhanced VEGFR3 phosphorylation in the kidney, normalized the pattern of the pericystic network of vessels, and widened the large lymphatics in Pkd1(nl/nl) mice. These effects were associated with significant reductions in cystic disease, BUN and serum creatinine levels. Furthermore, VEGFC administration reduced M2 macrophage pericystic infiltrate, which has been implicated in the progression of PKD. VEGFC administration also improved cystic disease in Cys1(cpk/cpk) mice, a model of autosomal recessive PKD, leading to a modest but significant increase in lifespan. Overall, this study highlights VEGFC as a potential new treatment for some aspects of PKD, with the possibility for synergy with current epithelially targeted approaches.

HA-ving lymphatics improves lung transplantation.

Lung allografts are prone to rejection, even though recipients undergo aggressive immunosuppressive therapy. Lymphatic vessels serve as conduits for immune cell trafficking and have been implicated in the mediation of allograft rejection. In this issue of the JCI, Cui et al. provide compelling evidence that lymphatic vessel formation improves lung allograft survival in a murine transplant model. Moreover, their data suggest a potential mechanism for the beneficial effects of lymphatics that does not involve immune cell or antigen transport. Together, the results of this study provide new insight into the role of lymphatic vessels in transplant tolerance.

Therapeutic lymphangiogenesis ameliorates established acute lung allograft rejection.

Lung transplantation is the only viable option for patients suffering from otherwise incurable end-stage pulmonary diseases such as chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. Despite aggressive immunosuppression, acute rejection of the lung allograft occurs in over half of transplant recipients, and the factors that promote lung acceptance are poorly understood. The contribution of lymphatic vessels to transplant pathophysiology remains controversial, and data that directly address the exact roles of lymphatic vessels in lung allograft function and survival are limited. Here, we have shown that there is a marked decline in the density of lymphatic vessels, accompanied by accumulation of low-MW hyaluronan (HA) in mouse orthotopic allografts undergoing rejection. We found that stimulation of lymphangiogenesis with VEGF-C156S, a mutant form of VEGF-C with selective VEGFR-3 binding, alleviates an established rejection response and improves clearance of HA from the lung allograft. Longitudinal analysis of transbronchial biopsies from human lung transplant recipients demonstrated an association between resolution of acute lung rejection and decreased HA in the graft tissue. Taken together, these results indicate that lymphatic vessel formation after lung transplantation mediates HA drainage and suggest that treatments to stimulate lymphangiogenesis have promise for improving graft outcomes.

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.

Lymph node transfer and perinodal lymphatic growth factor treatment for lymphedema.

OBJECTIVE: Our objective was to define the optimal growth factor treatment to be used in combination with lymph node transfer to normalize lymphatic vascular anatomy. BACKGROUND: In the lymph node transfer method, lymphatic anastomoses are expected to form spontaneously. However, lymphangiogenic growth factor therapies have shown promising results in preclinical models of lymphedema. METHODS: The inguinal lymphatic vasculature of pigs was surgically destroyed around the inguinal lymph node. To enhance the regrowth of the lymphatic network in the defected area, adenoviral vascular endothelial growth factor C (VEGF-C) was administered intranodally or perinodally. Control animals received injections of saline or control vector. The lymphangiogenic effect of the growth factor therapy and any potential adverse effects associated with the 2 alternative delivery routes were examined 2 months postoperatively. RESULTS: Both routes of growth factor administration induced robust growth of lymphatic vessels and helped to preserve the structure of the transferred lymph nodes in comparison with the controls. The lymph nodes of the control treated animals regressed in size and their nodal structure was partly replaced by fibro-fatty scar tissue. Intranodally injected adenoviral VEGF-C and adenoviral vector encoding control gene LacZ induced macrophage accumulation inside the node, whereas perinodal administration of VEGF-C did not have this adverse effect. CONCLUSIONS: Lymphangiogenic growth factors improve lymphatic vessel regeneration and lymph node function after lymph node transfer. The perinodal route of delivery provides a basis for future clinical trials in lymphedema patients.

Extracorporeal shock wave therapy combined with vascular endothelial growth factor-C hydrogel for lymphangiogenesis.

BACKGROUND/AIMS: Lymphedema is a clinically incurable disease that occurs commonly after lymph node dissection and/or irradiation. Several studies have recently demonstrated that extracorporeal shock wave therapy (ESWT) could promote lymphangiogenesis associated with expression of vascular endothelial growth factor (VEGF)-C. This research concerned primarily the synergistic effect of ESWT combined with VEGF-C incorporated hydrogel (VEGF-C hydrogel) combination therapy for promoting lymphangiogenesis and ultimately alleviating lymphedema. METHODS: The VEGF-C hydrogel was applied to the injury site in a mouse model of lymphedema and then regularly underwent ESWT (0.05 mJ/mm(2), 500 shots) every 3 days for 4 weeks. RESULTS: Four weeks after the treatment, mice treated with VEGF-C hydrogel and ESWT showed signs of the greatest decrease in edema/collagenous deposits when compared with the other experimental group. LYVE-1-positive vessels also revealed that the VEGF-C/ESWT group had significantly induced the growth of new lymphatic vessels compared to the other groups. Western blot analysis showed that expression of VEGF-C (1.24-fold) and VEGF receptor-3 (1.41-fold) was significantly increased in the VEGF-C/ESWT group compared to the normal group. CONCLUSION: These results suggested that VEGF-C and ESWT had a synergistic effect and were very effective in alleviating the symptoms of lymphedema and promoting lymphangiogenesis.