Short synthetic endostatin peptides inhibit endothelial migration in vitro and endometriosis in a mouse model

Applications of nanomaterials in endometriosis treatment

Endometriosis is a common disease of the reproductive system in women of childbearing age with an unclear pathogenesis. Endometriosis mainly manifests as dysmenorrhea, abdominal pain, and infertility. Currently, medical therapy and surgical treatment are usually used for endometriosis treatment. However, due to the high recurrence rate and many complications, it has greatly affected patients' quality of life. Nanotechnology is a new technology that mainly investigates the characteristics and applications of nanomaterials. To date, nanotechnology has received widespread attention in the field of biomedicine. Nanomaterials can not only be used as drugs to treat endometriosis directly, but also enhance the therapeutic effect of endometriosis by delivering drugs, siRNA, antibodies, vesicles, etc. This review comprehensively discusses nanomaterial-based therapies for endometriosis treatment, such as nanomaterial-based gene therapy, photothermal therapy, immunotherapy, and magnetic hyperthermia, which provides a theoretical reference for the clinical application of nanotechnology in the treatment of endometriosis.

Running exercise improves spatial learning and memory ability and enhances angiogenesis in the cerebral cortex via endogenous nitric oxide

BACKGROUND

The molecular mechanisms by which exercise improves brain function and capillaries in the cerebral cortex are unclear. Exercise can increase the expression of nitric oxide (NO) in the brain, and endogenous NO is thought to exert beneficial effects on proangiogenic factors, antiangiogenic factors and brain function. Therefore, we hypothesized that running exercise might improve brain function and enhance angiogenesis through endogenous NO.

METHODS AND RESULTS

The following three groups of rats were administered intracerebroventricular (i.c.v.) injections before running exercise each day for 4 weeks: exercise+L-NAME group (i.c.v. L-NAME, an NO synthase blocker, dose: 1 μmol/μl and 5 μl/day; treadmill exercise, 20 min/day), exercise group (i.c.v. normal saline, 5 μl/day; treadmill exercise, 20 min/day), and sham group (i.c.v. normal saline, 5 μl/day; no treadmill exercise). Subsequently, the spatial learning and memory abilities were tested using a Morris water maze, and the nitric oxide synthase (NOS) activity in the cerebral cortex in each group of rats was measured using a method involving nitric acid reductase and metabolic chemistry. The parameters of the cortical capillaries were quantitatively investigated using an immunohistochemistry technique and stereological methods. The expression levels of proangiogenic factors (VEGF and FGF-2) and an antiangiogenic inhibitor (endostatin) in the cerebral cortex were tested using a Western blot analysis. Running exercise significantly improved the rats' spatial learning and memory abilities and increased NOS activity in the cortex. Running exercise also subsequently improved the expression of proangiogenic factors (VEGF and FGF-2) and the length, volume and surface area of capillaries and reduced the expression of antiangiogenic factors (endostatin) in the cortex. In contrast, the L-NAME treatment attenuated the effects of running exercise.

CONCLUSIONS

Running exercise regulates proangiogenic factors, antiangiogenic factors and angiogenesis in the cerebral cortex via a partially NO-dependent mechanism, and influencing endogenous NO might potentially affect the exercise-related beneficial effects on cognitive ability and cortical capillaries.

Effects of ranibizumab and zoledronic acid on endometriosis in a rat model

PURPOSE

To investigate the histological efficacy of ranibizumab and zoledronic acid in an experimentally induced endometriosis model as compared with danazol, buserelin acetate and dienogest.

METHODS

Endometrial implants were introduced in 52 female Wistar albino rats, which were then randomly divided into six groups. The animals were, respectively, given dienogest, danazol, buserelin acetate, zoledronic acid, ranibizumab and 0.9% NaCl. After 4 weeks, the volumes and histopathological properties of the implants were evaluated and the implants were excised completely at the third laparotomy. A histopathological scoring system was used to evaluate the preservation of epithelia. Endometrial explants were evaluated immunohistochemically.

RESULTS

Among the groups, the histological score was significantly lower in the zoledronic acid and ranibizumab groups compared with the controls (p < 0.001). There were no significant differences regarding ellipsoidal volume levels between groups (p > 0.05). However, there was a statistically significant difference regarding cell numbers according to the degree of Bcl-2, NF-κB, and CD31 staining (p < 0.001). There was no statistically significant difference in Bcl-2, CD31, or NF-κB staining in the binary comparisons between the other groups (p > 0.05). For Bcl-2 staining, the staining rate of the group treated with zoledronic acid was significantly lower compared with the dienogest and danazol groups (p < 0.05). The staining rates of CD31 and NF-κB were significantly lower in the zoledronic acid and ranibizumab groups compared with the controls (p < 0.05).

CONCLUSION

According to these results, zoledronic acid and ranibizumab may be putative candidates for the treatment of endometriosis.

The Effect of Novel Medical Nonhormonal Treatments on the Angiogenesis of Endometriotic Lesions

Importance

Irrespective of the precise mechanisms leading to endometriosis, angiogenesis is essential for the establishment and long-term proliferation of the disease. As current surgical and medical management options for women with endometriosis have substantial drawbacks and limitations, novel agents are needed and molecules targeting the angiogenic cascade could serve as potential candidates.

Objective

Our aim was to review current data about the role of angiogenesis in the pathophysiology of endometriosis and summarize the novel antiangiogenic agents that could be potentially used in clinical management of patients with endometriosis.

Evidence Acquisition

Original research and review articles were retrieved through a computerized literature search.

Results

Loss of balance between angiogenic activators and suppressors triggers the nonphysiological angiogenesis observed in endometriotic lesions. Several proangiogenic mediators have been identified and most of them have demonstrated increased concentrations in the peritoneal fluid and/or serum of women with endometriosis. Among the antiangiogenic molecules, anti-vascular endothelial growth factor agents, dopamine agonists, romidepsin, and statins have shown the most promising results so far.

Conclusions and Relevance

Given the limitations of current treatments of endometriosis, there is a need for novel, more efficient agents. Antiangiogenic molecules could be used potentially in clinical management of women with endometriosis; however, their safety and efficiency should be carefully assessed prior to that. Further large prospective trials in humans are needed before any treatment is introduced into daily clinical practice.

Effects of atorvastatin and resveratrol against the experimental endometriosis; evidence for glucose and monocarboxylate transporters, neoangiogenesis

The current study was conducted to investigate the therapeutic effects of atorvastatin (ATV) and resveratrol (RVT) in sole and simultaneous forms of administration against the symbiosis between glucose transporters 1 and 3 (GLUT-1 and GLUT-3), monocarboxylate transporters 1 a and 4 (MCT-1 and MCT-4) and neovascularization in ectopic endometrial tissue (EET). For this purpose, the experimental endometriosis was induced in 24 virgin female Wistar rats, and then the rats were divided into non-treated endometriosis-induced (ENDO-sole), AVT-treated (5 mg kg-1), RVT-treated (40 mg kg-1) and AVT +RVT-treated groups (n = 6 rats in each group). Following 28 days from the experimental endometriosis induction, the EETs were collected and the EETs size, neovascularization ratio, and expression levels of GLUT-1, GLUT-3, MCT-1, and MCT-4 were analyzed by qRT-PCR and immunohistochemistry (IHC). The AVT and RVT sole and simultaneous-treated animals exhibited decreased EET sizes and neovascularization. Moreover, the mRNA levels of GLUT-1, GLUT-3, MCT-1, and MCT-4, as well as GLUT-1⁺, GLUT-3⁺, and MCT-4⁺ cells distribution per mm² of tissue were decreased in AVT and RVT sole and simultaneous-treated groups. Our findings showed that the AVT and RVT, especially in the simultaneous form of administration, could decrease the neovascularization development in the EETs by suppressing the GLUTs (1 and 3) and MCTs (1 and 4) expressions. Therefore, it can be concluded that the simultaneous administration of AVT and RVT can inhibit the EET's establishment and development through suppressing glycolysis and neovascularization.

Basic mechanisms of vascularization in endometriosis and their clinical implications

BACKGROUND

Vascularization is a major hallmark in the pathogenesis of endometriosis. An increasing number of studies suggests that multiple mechanisms contribute to the vascularization of endometriotic lesions, including angiogenesis, vasculogenesis and inosculation.

OBJECTIVE AND RATIONALE

In this review, we provide an overview of the basic mechanisms of vascularization in endometriosis and give special emphasis on their future clinical implications in the diagnosis and therapy of the disease.

SEARCH METHODS

Literature searches were performed in PubMed for English articles with the key words 'endometriosis', 'endometriotic lesions', 'angiogenesis', 'vascularization', 'vasculogenesis', 'endothelial progenitor cells' and 'inosculation'. The searches included both animal and human studies. No restriction was set for the publication date.

OUTCOMES

The engraftment of endometriotic lesions is typically associated with angiogenesis, i.e. the formation of new blood vessels from pre-existing ones. This angiogenic process underlies the complex regulation by angiogenic growth factors and hormones, which activate intracellular pathways and associated signaling molecules. In addition, circulating endothelial progenitor cells (EPCs) are mobilized from the bone marrow and recruited into endometriotic lesions, where they are incorporated into the endothelium of newly developing microvessels, referred to as vasculogenesis. Finally, preformed microvessels in shed endometrial fragments inosculate with the surrounding host microvasculature, resulting in a rapid blood supply to the ectopic tissue. These vascularization modes offer different possibilities for the establishment of novel diagnostic and therapeutic approaches. Angiogenic growth factors and EPCs may serve as biomarkers for the diagnosis and classification of endometriosis. Blood vessel formation and mature microvessels in endometriotic lesions may be targeted by means of anti-angiogenic compounds and vascular-disrupting agents.

WIDER IMPLICATIONS

The establishment of vascularization-based approaches in the management of endometriosis still represents a major challenge. For diagnostic purposes, reliable angiogenic and vasculogenic biomarker panels exhibiting a high sensitivity and specificity must be identified. For therapeutic purposes, novel compounds selectively targeting the vascularization of endometriotic lesions without inducing severe side effects are required. Recent progress in the field of endometriosis research indicates that these goals may be achieved in the near future.

New developments in the medical treatment of endometriosis

Endometriosis affects 1 in 10 women of reproductive-age. The current treatments are surgical and hormonal but have limitations, including the risk of recurrence, side effects, contraceptive action for women who desire pregnancy, and cost. New treatments include gonadotropin-releasing hormone analogues, selective progesterone (or estrogen) receptor modulators, aromatase inhibitors, immunomodulators, and antiangiogenic agents. Further research is needed into central sensitization, local neurogenesis, and the genetics of endometriosis to identify additional treatment targets. A wider range of medical options allows for the possibility of precision health and a more personalized treatment approach for women with endometriosis.

Efficacy of Anti-VEGF/VEGFR Agents on Animal Models of Endometriosis: A Systematic Review and Meta-Analysis

Background/Objective

Vascular endothelial growth factor (VEGF) is the most important promotor of angiogenesis. Some studies indicate that anti-angiogenic agents that interfere with VEGF and its receptor (VEGFR), i.e., anti-VEGF/VEGFR agents, may be applied to treat endometriosis. This meta-analysis investigated the efficacy of anti-VEGF/VEGFR agents in animal models of endometriosis.

Methods

A systematic literature search was performed for animal studies published in English or Chinese from January 1995 to June 2016, which evaluated the effect of anti-VEGF/VEGFR agents on endometriosis. The databases were: PubMed, Web of Science, BIOSIS, Embase, and CNKI. The quality of included studies was assessed using the SYRCLE tool. The random-effect models were used to combine the results of selected studies. Heterogeneity was assessed using H²statistic and I² statistic. Subgroup analyses were performed to determine the source of heterogeneity in endometriosis scores and follicle numbers.

Results

We identified 13 studies that used anti-VEGF/VEGFR agents in various animal models. The meta-analysis showed that anti-VEGF/VEGFR agents were associated with smaller size (standardized mean difference (SMD) –0.96, 95% CI –1.31 to –0.62; P < 0.0001) and weight (SMD –1.70, 95% CI –2.75 to –0.65; P = 0.002) of endometriosis lesions, relative to the untreated controls, as well as a lower incidence rate of endometriosis (risk ratio 0.26, 95% CI 0.07 to 0.93; P = 0.038) and endometriosis score (SMD –1.17, 95% CI –1.65 to –0.69; P < 0.0001); the number of follicles were similar (SMD –0.78, 95% CI –1.65 to 0.09; P = 0.08).

Conclusions

Anti-VEGF/VEGFR agents appeared to inhibit the growth of endometriosis, with no effect on ovarian function. Anti-angiogenic therapy may be a novel strategy in treating endometriosis.

Endostatin's emerging roles in angiogenesis, lymphangiogenesis, disease, and clinical applications

BACKGROUND

Angiogenesis is the process of neovascularization from pre-existing vasculature and is involved in various physiological and pathological processes. Inhibitors of angiogenesis, administered either as individual drugs or in combination with other chemotherapy, have been shown to benefit patients with various cancers. Endostatin, a 20-kDa C-terminal fragment of type XVIII collagen, is one of the most potent inhibitors of angiogenesis.

SCOPE OF REVIEW

We discuss the biology behind endostatin in the context of its endogenous production, the various receptors to which it binds, and the mechanisms by which it acts. We focus on its inhibitory role in angiogenesis, lymphangiogenesis, and cancer metastasis. We also present emerging clinical applications for endostatin and its potential as a therapeutic agent in the form a short peptide.

MAJOR CONCLUSIONS

The delicate balance between pro- and anti-angiogenic factors can be modulated to result in physiological wound healing or pathological tumor metastasis. Research in the last decade has emphasized an emerging clinical potential for endostatin as a biomarker and as a therapeutic short peptide. Moreover, elevated or depressed endostatin levels in diseased states may help explain the pathophysiological mechanisms of the particular disease.

GENERAL SIGNIFICANCE

Endostatin was once sought after as the 'be all and end all' for cancer treatment; however, research throughout the last decade has made it apparent that endostatin's effects are complex and involve multiple mechanisms. A better understanding of newly discovered mechanisms and clinical applications still has the potential to lead to future advances in the use of endostatin in the clinic.

Antiangiogenesis therapy of endometriosis using PAMAM as a gene vector in a noninvasive animal model

OBJECTIVE

To evaluate the characteristics and antiangiogenic effects of endostatin-loaded PAMAM on endometriosis in a noninvasive animal model.

MATERIALS AND METHODS

A noninvasive animal model was established by injecting adenovirus-GFP transfected endometrial stromal and glandular epithelial cells subcutaneously into nude mice. Endostatin-loaded PAMAM was prepared and identified by transmission electron microscopy. For in vitro studies, the DNA protection and cytotoxicity of PAMAM were investigated and compared with Lipofectamine 2000. For in vivo study, endostatin-loaded PAMAM was injected into the noninvasive model and evaluated by continuously observing the fluorescent lesion, lesion weight, microvessel density and VEGF immunostaining.

RESULTS

Compared with Lipofectamine 2000, PAMAM and HC PAMAM-ES group, MC PAMAM-ES group and LC PAMAM-ES group demonstrated a better stromal cells protective such that MC PAMAM-ES group of CCK8 was 0.617 ± 0.122 at 24 hr and 0.668 ± 0.143 at 48 hr and LC PAMAM-ES group of CCK8 was 0.499 ± 0.103 at 24 hr and 0.610 ± 0.080 at 48 hr in stromal cells (P < 0.05) but similar cytotoxicity in glandular epithelial cells in vitro. After 16 hrs of digestion, DNA decreased slightly under the protection of PAMAM. Endostatin-loaded PAMAM of HD PAMAM-ES group and LD PAMAM-ES group inhibited the growth of the endometriotic lesion in vivo at days 15, 20, 25 and 30 detected by noninvasive observation after injecting one dose endostatin of various medicines into the endometrial lesion in each mouse on day 10 (P < 0.05) and confirmed by lesion weight at day 30 with HD PAMAM-ES group being 0.0104 ± 0.0077 g and LD PAMAM-ES group being 0.0140 ± 0.0097 g (P < 0.05). Immunohistochemistry results showed that endostatin-loaded PAMAM reduced the microvessel density 3.8 ± 2.4 especially in HD PAMAM-ES group in the lesion (P < 0.05).

CONCLUSION

Endostatin-loaded PAMAM inhibits the development of endometriosis through an antiangiogenic mechanism and can be observed through the noninvasive endometriosis model.

Is adenomyosis a problem in reproduction and fertility?

Adenomyosis is defined as the presence of glandular foci beside the endometrium of uterus: in the myometrium and/or perimetrium depending on the progress of the disorder. So far, adenomyosis has been diagnosed in women and rodents, and studies conducted on cows have been rare. In this review we: (1) summarize the knowledge regarding adenomyosis, (2) compare the symptoms and aetiopathology between women and cows, (3) describe angiogenic uterine processes related to adenomyosis development and (4) outline the influence of adenomyosis on proper fertility processes in cattle (conception and fertility rates).

Activated AKT pathway promotes establishment of endometriosis

The pathogenesis of endometriosis remains unclear, and relatively little is known about the mechanisms that promote establishment and survival of the disease. Previously, we demonstrated that v-akt murine thymoma viral oncogene homolog (AKT) activity was increased in endometriosis tissues and cells from ovarian endometriomas and that this increase promoted cell survival as well as decreased levels of progesterone receptor. The objective of this study was to demonstrate a role for AKT in the establishment of ectopic lesions. First, a dose-dependent inhibition of AKT in stromal cells from human ovarian endometriomas (OSIS) as well as endometrial stromal cells from disease-free patients (ESC) with the allosteric AKT inhibitor MK-2206 was demonstrated by decreased levels of phosphorylated (p)(Ser473)-AKT. Levels of the AKT target protein, p(Ser256)-forkhead box O1 were increased in OSIS cells, which decreased with MK-2206 treatment, whereas levels of p(Ser9)-glycogen synthase kinase 3β did not change in response to MK-2206. Although MK-2206 decreased viability of both OSIS and ESC in a dose-dependent manner, proliferation of OSIS cells was differentially decreased significantly compared with ESC. Next, the role of hyperactive AKT in the establishment of ectopic lesions was studied using the bigenic, PR(cre/+)Pten(f/+) heterozygous mouse. Autologous implantation of uterine tissues was performed in these mice. After 4 weeks, an average of 4 ± 0.33 lesions per Pten(f/+) mouse and 7.5 ± 0.43 lesions in the PR(cre/+)Pten(f/+) mouse were found. Histological examination of the lesions showed endometrial tissue-like morphology, which was similar in both the Pten(f/+) and PR(cre/+)Pten(f/+) mice. Treatment of mice with MK-2206 resulted in a significantly decreased number of lesions established. Immunohistochemical staining of ectopic lesions revealed decreased p(Ser473)-AKT and the proliferation marker Ki67 from MK-2206-treated mice compared with vehicle-treated mice. Furthermore, levels of FOXO1 and progesterone receptor increased in lesions of mice receiving MK-2206. These results demonstrate that heightened AKT activity plays an active role in the establishment of ectopic endometrial tissues.

Oestrogen-induced angiogenesis promotes adenomyosis by activating the Slug-VEGF axis in endometrial epithelial cells

Adenomyosis is an oestrogen-dependent disease characterized by the invasion of endometrial epithelial cells into the myometrium of uterus, and angiogenesis is thought to be required for the implantation of endometrial glandular tissues during the adenomyotic pathogenesis. In this study, we demonstrate that compared with eutopic endometria, adenomyotic lesions exhibited increased vascularity as detected by sonography. Microscopically, the lesions also exhibited an oestrogen-associated elevation of microvascular density and VEGF expression in endometrial epithelial cells. We previously reported that oestrogen-induced Slug expression was critical for endometrial epithelial–mesenchymal transition and development of adenomyosis. Our present studies demonstrated that estradiol (E2) elicited a Slug-VEGF axis in endometrial epithelial cells, and also induced pro-angiogenic activity in vascular endothelial cells. The antagonizing agents against E2 or VEGF suppressed endothelial cells migration and tubal formation. Animal experiments furthermore confirmed that blockage of E2 or VEGF was efficient to attenuate the implantation of adenomyotic lesions. These results highlight the importance of oestrogen-induced angiogenesis in adenomyosis development and provide a potential strategy for treating adenomyosis through intercepting the E2-Slug-VEGF pathway.

The development of endometriosis in a murine model is dependent on the presence of dendritic cells

Endometriosis is a common condition associated with pelvic pain and infertility. This study group has previously shown that supplementation of dendritic cells led to enhancement of endometriosis lesion growth and angiogenesis. This study determined whether endometriosis is dependent on the presence of endogenous dendritic cells. Surgical induction of endometriosis was performed in CD11c⁺ DTR/GFP transgenic (Tg) female mice in which dendritic cells were ablated upon injection of diphtheria toxin (DT). Mice were allocated into four groups (n=5 each): group I, wild-type mice treated with vehicle; group II, wild-type mice treated with DT; group III, Tg mice treated with DT; and group IV, Tg mice treated with vehicle. After 10 days, mice were killed and endometriosis lesions were analysed by flow cytometry. DT treatment led to ablation of dendritic cells in spleens and endometriosis lesions in Tg mice while no ablation was observed in controls. Corresponding to dendritic cell ablation, endometriosis lesions in group III were ∼5-fold smaller than in the control groups (ANOVA P<0.0001). This study suggests that endometriosis development is dependent on the presence of endogenous dendritic cells. Therapies designed to inhibit dendritic cell infiltration as possible treatments for endometriosis warrant further study.

Animal models for anti-angiogenic therapy in endometriosis

Endometriosis is a gynecological disease characterized by the growth of endometrium outside of the uterine cavity. It is often associated with dysmenorrhea, dyspareunia, pelvic pain and infertility. One of the key requirements for endometriotic lesions to survive is development of a blood supply to support their growth. Indeed, dense vascularization is characteristic feature of endometriotic lesions. This has led to the idea that suppression of blood vessel growth (anti-angiogenic therapy) may be a successful therapeutic approach for endometriosis. Potential effectiveness of anti-angiogenic therapies has been assessed in some animal models but there are no reports of human clinical trials. Without understanding the specific mechanism by which endometriosis lesions establish a new blood supply, short-term animal experiments will have limited value for translation into human medicine. Further, it is crucial to use appropriate animal models to assess efficacy of anti-angiogenic compounds. Syngeneic and autologous rodent models, where endometrial fragments are auto-transplanted into the peritoneal cavity are commonly used in anti-angiogenic therapy studies. Another approach is xenograft models where human endometrium is engrafted into immunodeficient mice. Here we review the animal models and experimental techniques used to evaluate anti-angiogenic therapies for endometriosis. We also review our own work on the role of stromal cell derived factor-1 in the recruitment of endothelial progenitor cells in endometriotic lesion angiogenesis, and the effects of the anti-angiogenic peptide ABT-898, a thrombospondin-1 mimetic, on endometriotic lesion growth and vascular development.

Anastrozole and celecoxib for endometriosis treatment, good to keep them apart?

Endometriosis is a benign gynecological disease. Cyclooxygenase-2 (COX-2) and aromatase proteins have been shown to be overexpressed in eutopic endometrium from women suffering from this disease compared to disease-free women. Furthermore, inhibition of these molecules individually was demonstrated to have antiproliferative and proapoptotic effects both in vitro and in vivo in several models. In this study, the effect of combining celecoxib, a selective COX-2 inhibitor, and anastrozole, an aromatase inhibitor, on the implantation and growth of endometriotic like lesions in a murine model of endometriosis was evaluated. Endometriosis was surgically induced in female BALB/c mice. After 28 days of treatment with celecoxib, anastrozole, or their combination, animals were killed and lesions were counted, measured, excised, and fixed. Immunohistochemistry for proliferating cell nuclear antigen and CD34 was performed for assessment of cell proliferation and vascularization. TUNEL technique was performed for apoptosis evaluation. Celecoxib was the only treatment to significantly reduce the number of lesions established per mouse, their size and vascularized area. In addition, cell proliferation was significantly diminished and apoptosis was significantly enhanced by both individual treatments. When the therapies were combined, they reversed their effects. These results confirm that celecoxib and anastrozole separately decrease endometriotic growth, but when combined they might have antagonizing effects.

Vascular endothelial growth factor C is increased in endometrium and promotes endothelial functions, vascular permeability and angiogenesis and growth of endometriosis

Endometriosis is an angiogenesis-dependent disease. Many studies demonstrated inhibition of angiogenesis leads to inhibition of endometriotic growth, however underlying mechanism is still not fully understood. Our previous study suggested vascular endothelial growth factor C (VEGF-C) as a target of anti-angiogenesis therapy for endometriosis. In this study, VEGF-C in endometrium and its role in angiogenesis of endometriosis were studied. Human endometrium were obtained from women with and without endometriosis for molecular studies. VEGF-A, VEGF-B, VEGF-C and VEGF-D mRNA and proteins in eutopic and ectopic endometrium were measured. Human endothelial cells were transfected with VEGF-C siRNA in vitro, effects of VEGF-C on endothelial cell migration, invasion and tube formation were investigated in vitro. Angiogenesis was inhibited in wild type mice, vascular permeability in dermal skin was determined in vivo. Transplanted endometrium were inhibited by VEGF-C siRNA in immunocompromised mice, development, growth and angiogenesis of the experimental endometriosis were compared in vivo. The results showed that VEGF-C mRNA and protein were increased in eutopic and ectopic endometrium of endometriosis patients. VEGF-C siRNA significantly inhibited endothelial cell migration and tube formation. VEGF-C siRNA significantly inhibited development and angiogenesis of the experimental endometriotic lesions in mice. Supplementation and over-expression of VEGF-C significantly reversed the inhibitory effects on the endothelial functions, vascular permeability and endometriotic growth. In conclusion, VEGF-C is increased in endometrium and it promotes endothelial functions, vascular permeability and development of experimental endometriosis. VEGF-C is important for angiogenesis in endometriosis.

Endostatin Gene Therapy for Endometriosis in Rats

Objective:

Endostatin gene therapy for endometriosis was studied in an experimental autotransplantation model in rats.

Methods:

Endometriotic lesions were transfected by intralesional injection of the plasmid lipofectamine-endostatinpBud (group 1), lipofectamine-pBud (empty vector; group 2) or phosphatebuffered saline (group 3). Endostatin mRNA and protein levels in lesions were evaluated by quantitative real-time reverse transcription-polymerase chain reaction and Western blot analysis. Endostatin and vascular endothelial growth factor (VEGF) protein levels in serum, and microvessel density (MVD) and matrix metalloproteinase (MMP)-2 protein levels in endometriotic lesions, were also determined.

Results:

Lipofectamine- endostatin-pBud injection increased endostatin mRNA and protein levels in lesions. Lesions were significantly smaller, and serum VEGF levels significantly lower, in group 1 versus controls. Serum VEGF was significantly and negatively correlated with serum endostatin. In group 1, MMP-2 levels and MVD were significantly lower versus controls. MMP-2 level was negatively correlated with endostatin.

Conclusions:

Gene therapy with endostatin appears to be an effective treatment for endometriosis. Restoration of endostatin gene expression by gene transfer in vivo might be a potential gene therapy approach for human endometriosis.

Slit2 overexpression results in increased microvessel density and lesion size in mice with induced endometriosis

We recently reported that Slit/Roundabout (ROBO) 1 pathway may be a constituent biomarker for recurrence of endometriosis, likely through promoting angiogenesis. In this study, we sought to determine as whether Slit2 overexpression can facilitate angiogenesis, increase lesion size, and induce hyperalgesia in mice with induced endometriosis. We used 30 Slit2 transgenic (S) and 29 wild-type (W) mice and cross-transplanted endometrial fragments from S to W (group SW) and vice versa (group WS), and also within the S and W (groups SS and WW, respectively), into the peritoneal cavity, inducing endometriosis. We also performed a sham surgery within both S and W mice (groups Sm and Wm, respectively). The size of the ectopic implants, microvessel density (MVD) and immunoreactivity to ROBO1, and vascular endothelial cell growth factor (VEGF) in ectopic and eutopic endometrium, along with hotplate and tail-flick tests in all mice, were then evaluated. We found that the induction of endometriosis resulted in generalized hyperalgesia, which was unaffected by Slit2 overexpression. Slit2 overexpression did increase the lesion size significantly and correlated positively with the MVD in ectopic and eutopic endometrium. Slit2 expression levels appear to correlate with the MVD, but not with VEGF immunoreactivity, in ectopic endometrium. Consequently, we conclude that Slit2 may play an important role in angiogenesis in endometriosis. The increased angiogenesis, as measured by MVD, but not VEGF immunoreactivity, likely resulted in increased lesion size in induced endometriosis. Thus, SLIT2/ROBO1 pathway may be a potential therapeutic target for treating endometriosis.

Thrombospondin-1 mimetic peptide ABT-898 affects neovascularization and survival of human endometriotic lesions in a mouse model

Endometriosis is a common cause of pelvic pain and infertility in women, and a common indication for hysterectomy, yet the disease remains poorly diagnosed and ineffectively treated. Because endometriotic lesions require new blood supply for survival, inhibiting angiogenesis could provide a novel therapeutic strategy. ABT-898 mimics the antiangiogenic properties of thrombospondin-1, so we hypothesized that ABT-898 will prevent neovascularization of human endometriotic lesions and that ABT-898 treatment will not affect reproductive outcomes in a mouse model. Endometriosis was induced in BALB/c-Rag2(-/-)Il2rg(-/-) mice by surgical implantation of human endometrial fragments in the peritoneal cavity. Mice received daily injections of ABT-898 for 21 days. Flow cytometry was performed to measure circulating endothelial progenitor cells in peripheral blood. Cytokines were measured in plasma samples. Half of the ABT-898-treated and control mice were euthanized to assess neovascularization of endometriotic lesions, using CD31(+) immunofluorescence. The remaining mice were mated and euthanized at gestation day 12. Endometriotic lesions increased circulating endothelial progenitor cells 13 days after engraftment, relative to baseline. Endometriotic lesions from ABT-898-treated mice exhibited reduced neovascularization, compared with controls, and lesions had fewer CD31(+) microvessels. Chronic treatment with ABT-898 did not lead to any fetal anomalies or affect litter size at gestation day 12, compared with controls. Our results suggest that ABT-898 inhibits neovascularization of human endometriotic lesions without affecting mouse fecundity.

Mouse model of surgically-induced endometriosis by auto-transplantation of uterine tissue

Endometriosis is a chronic, painful disease whose etiology remains unknown. Furthermore, treatment of endometriosis can require laparoscopic removal of lesions, and/or chronic pharmaceutical management of pain and infertility symptoms. The cost associated with endometriosis has been estimated at 22 billion dollars per year in the United States. To further our understanding of mechanisms underlying this enigmatic disease, animal models have been employed. Primates spontaneously develop endometriosis and therefore primate models most closely resemble the disease in women. Rodent models, however, are more cost effective and readily available. The model that we describe here involves an autologous transfer of uterine tissue to the intestinal mesentery (Figure 1) and was first developed in the rat and later transferred to the mouse. The goal of the autologous rodent model of surgically-induced endometriosis is to mimic the disease in women. We and others have previously shown that the altered gene expression pattern observed in endometriotic lesions from mice or rats mirrors that observed in women with the disease. One advantage of performing the surgery in the mouse is that the abundance of transgenic mouse strains available can aid researchers in determining the role of specific components important in the establishment and growth of endometriosis. An alternative model in which excised human endometrial fragments are introduced to the peritoneum of immunocompromised mice is also widely used but is limited by the lack of a normal immune system which is thought to be important in endometriosis. Importantly, the mouse model of surgically induced endometriosis is a versatile model that has been used to study how the immune system, hormones and environmental factors affect endometriosis as well as the effects of endometriosis on fertility and pain.

Circulating endothelial progenitor cells are up-regulated in a mouse model of endometriosis

Endometriosis is a debilitating disease characterized by the growth of ectopic endometrial tissue. It is widely accepted that angiogenesis plays an integral part in the establishment and growth of endometriotic lesions. Recent data from a variety of angiogenesis-dependent diseases suggest a critical role of bone marrow–derived endothelial progenitor cells (EPCs) in neovascularization. In this study we examined the blood levels of EPCs and mature circulating endothelial cells in a mouse model of surgically induced endometriosis. Fluorescence-activated cell sorting analysis revealed elevated levels of EPCs in the blood of mice with endometriosis compared with control subject that underwent a sham operation. EPC concentrations positively correlated with the amount of endometriotic tissue and peaked 1 to 4 days after induction of disease. In a green fluorescent protein bone marrow transplant experiment we found green fluorescent protein–positive endothelial cells incorporated into endometriotic lesions but not eutopic endometrium, as revealed by flow cytometry and immunohistochemistry. Finally, treatment of endometriosis-bearing mice with the angiogenesis inhibitor Lodamin, an oral nontoxic formulation of TNP-470, significantly decreased EPC levels while suppressing lesion growth. Taken together, our data indicate an important role for bone marrow–derived endothelial cells in the pathogenesis of endometriosis and support the potential clinical use of anti-angiogenic therapy as a novel treatment modality for this disease.

The remedial effect of soluble interleukin-1 receptor type II on endometriosis in the nude mouse model

OBJECTIVE

Recent studies have shown that the local expression of soluble interleukin (IL) -1 receptor type II (sIL-1 RII) in endometrial tissue of women with endometriosis is decreased, and the depression of IL-1 RII was more significant in infertile women than that in fertile women with endometriosis. In this research, we investigated the remedial effect of sIL-1-RII administration on endometriosis in the nude mouse model.

METHODS

NINETEEN NUDE MODEL MICE WITH ENDOMETRIOSIS WERE RANDOMLY DIVIDED INTO THREE GROUPS: group A was treated by intraperitoneal administration with only sIL-1 RII for two weeks, group B was similarly treated with only IL-1, and group C (control) was administered saline . After 2 weeks, the size of the ectopic endometrial lesions was calculated, and the expression of vascular endothelial growth factor (VEGF) and B-cell lymphoma leukemia-2 (Bcl-2) were detected by immunohistochemistry. The IL-8 and VEGF levels in the peritoneal fluid (PF) and serum were also measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The mean size of ectopic endometrial lesion did not differ between the three groups (P > 0.05). Compared with the control, the expression of VEGF and Bcl-2 was significantly lower in group A, and higher in group B. In the three groups, the levels of IL-8 in the PF and serum were highest in group A, and lowest in group B.

CONCLUSION

sIL-1 RII may suppresse hyperplasia of ectopic endometriosis, perhaps by reducing the expression of certain cytokines, such as VEGF, IL-8, and Bcl-2, which could provide a new clinical strategy for the treatment of endometriosis.

New drugs in development for the treatment of endometriosis

Endometriosis is a common and enigmatic disease causing pelvic pain and infertility. Current treatment is mainly based on the use of surgery and ovarian suppressive agents. There is in particular the need for new therapeutic options able to allow a normal menstrual cycle to occur and also consent pregnancy. In the present review, we aimed to give a concise and practical overview in order to allow the clinician to clearly understand the level of development of these drugs. We have presented only treatments supported by in vivo researches with a special attention to studies in humans. Results show appealing new possibilities are emerging from agents counteracting the endometriosis-associated inflammation. Recent data also suggests that there is still the opportunity to refine the use of already available agents.

2-methoxyestradiol inhibits hypoxia-inducible factor-1{alpha} and suppresses growth of lesions in a mouse model of endometriosis

Endometriosis, the presence of ectopic endometrial tissue outside the uterine cavity, is a common disease affecting women during their reproductive years. Current therapeutic success is often unsatisfactory because of limited insight into disease mechanisms. Nevertheless, angiogenesis plays an essential role in the pathogenesis of the disease, making it a potential novel target for therapy. In the current study, we demonstrate in an established mouse model of endometriosis that transient hypoxia in transplanted endometriosis-like lesions results in the up-regulation of hypoxia-inducible factor-1alpha (HIF-1alpha), leading to the expression of vascular endothelial growth factor (VEGF), a key player in endometriosis-associated angiogenesis. Systemic treatment with the angiogenesis inhibitor 2-methoxyestradiol suppressed HIF-1alpha expression in vivo, resulting in a decreased downstream expression of HIF-1alpha target genes, such as for VEGF, phosphoglycerate kinase, and glucose transporter-1. 2-Methoxyestradiol also suppressed VEGF-induced vascular permeability, as demonstrated in a modified Miles assay. Finally, systemic treatment with 2-methoxyestradiol significantly inhibited the growth of endometriosis-like lesions in a dose-dependent manner. In conclusion, hypoxia appears to play an important role in the pathogenesis of endometriosis and endometriosis-associated angiogenesis, and the angiogenesis inhibitor 2-methoxyestradiol may be a potential candidate for systemic treatment in the future.

Dendritic cells support angiogenesis and promote lesion growth in a murine model of endometriosis

Endometriosis affects 10-15% of women and is associated with pelvic pain and infertility. Angiogenesis plays an essential role in its pathogenesis. Dendritic cells (DCs) were recently implicated in supporting tumor angiogenesis. As both tumors and endometriosis lesions depend on angiogenesis, we investigated the possibility that DCs may also play a role in endometriosis. We induced endometriosis in 8-wk-old female C57BL/6 mice by implantation of autologous endometrium into the peritoneal cavity. We observed an abundance of CD11c(+) DCs infiltrating sites of angiogenesis in endometriosis lesions. We noticed a similar pattern of infiltrating DCs at sites of angiogenesis in the peritoneal Lewis lung carcinoma tumor model. These DCs were immature (major histocompatability complex class II(low)) and expressed vascular endothelial growth factor receptor 2. Peritoneal implanted bone marrow-derived DCs (BMDCs) incorporated into both endometriosis lesions and into B16 melanoma tumors and enhanced their growth at 8 days compared with controls (5.1+/-2.5 vs. 1.5+/-0.5 mm(2), n=4 and 4, P<0.0001 for endometriosis; 67.6+/-15.1 vs. 22.7+/-14.6 mm(2), n=5 and 7, P=0.0004 for mouse melanoma). Finally, immature BMDCs but not mature BMDCs enhanced microvascular endothelial cell migration in vitro (219+/-51 vs. 93+/-32 cells, P=0.02). Based on these findings, we suggest a novel role for DCs in supporting angiogenesis and promoting lesion growth both in endometriosis and in tumors.

Angiogenesis and antiangiogenic therapy in endometriosis

Endometriosis, the presence of endometrium-like tissue outside of the uterine cavity, is a common disease among women of reproductive age. Typical symptoms include abdominal pain and painful menstruation. In addition, endometriosis is associated with reduced fertility. Current treatment modalities, the surgical removal of endometriotic lesions and the hormonal suppression of estrogen are associated with significant morbidity, side-effects and recurrence rates. Despite uncertainties about the pathophysiology of the disease it has recently become apparent that angiogenesis plays a pivotal role in endometriosis. This review focuses on a multitude of factors involved in the angiogenic phenotype of endometriosis demonstrating that many biological systems such as the immune system and steroid hormones are closely connected to angiogenic pathways in this disease. In addition, experimental and clinical data are discussed that concentrate on the inhibition of angiogenesis as a novel therapeutic approach for endometriosis.

In vitro and in vivo approaches to study angiogenesis in the pathophysiology and therapy of endometriosis

Endometriosis represents one of the most common gynaecological disorders. According to the implantation theory, angiogenesis is a major prerequisite for the initiation and progression of the disease. Thus, during the last decade, many studies have focused on the mechanisms regulating angiogenesis in endometriotic lesions. For this purpose, sophisticated in vitro and in vivo approaches have been established, which are highlighted in this review. Enzyme-linked immunosorbent assays demonstrate the imbalance of pro- and anti-angiogenic growth factors in isolated peritoneal fluid from endometriosis patients. Histological, immunohistochemical and gene expression analyses of endometriotic tissue provide detailed information on the angio-architecture of endometriotic lesions and the different growth factor expression by various cell populations. Moreover, cell culture systems are useful tools for the identification of hormonal and immunological factors involved in the angiogenic process. Finally, sophisticated in vivo models, such as rodent models of peritoneal endometriosis as well as the chorioallantoic membrane assay and the dorsal skinfold chamber, allow for the detailed analysis of blood vessel development in ectopic endometrium and the efficacy of angiogenesis inhibitors. The findings resulting from all these approaches will help to provide better insights into the pathophysiology of endometriosis and to establish new anti-angiogenic treatment strategies for the future.

Antiangiogenic therapies in endometriosis

Oral contraceptives, androgenic agents, progestins and gonadotropin-releasing hormone analogues have all been successfully used in the treatment of endometriosis. However, none of these drugs can eradicate the disease. It is widely accepted that the growth of newly formed blood vessels is essential for the establishment and growth of endometriotic lesions; therefore, inhibition of angiogenesis may offer a new option for treatment of this disorder. In this paper, we reviewed anti-vascular endothelial growth factor agents and other angiostatic drugs (i.e., TNP470, endostatin, anginex, rapamycin) that have been studied in laboratory and animal models of endometriosis. Although preliminary results are interesting, further investigations are required before clinical trials can be planned in humans.

A novel noninvasive model of endometriosis for monitoring the efficacy of antiangiogenic therapy

Endometriosis, the presence of ectopic endometrial tissue, is a common disease associated with high morbidity and socioeconomic problems. Angiogenesis, the formation of new blood vessels, plays an important role in the formation and growth of endometriotic lesions. We have created a novel, noninvasive model to monitor the growth of these lesions and the associated angiogenesis in vivo. First, we generated luciferase-expressing transgenic mice by inserting the human ubiquitin C promoter coupled to the firefly luciferase reporter. Injection of luciferin in these mice causes full-body bioluminescence, which can be detected using a low-light CCD camera. Endometrial tissue from these transgenic mice was surgically implanted into nonluminescent recipients. Bioluminescence of lesions was noninvasively imaged after intravenous or intraperitoneal injection of luciferin. Transabdominal luminescence compared well with the location of the transgenic endometriotic lesions, and lesion size correlated with the intensity of luminescence. Systemic treatment with the angiogenesis inhibitors caplostatin and endostatin peptide mP-1 delayed and suppressed the onset and intensity of the luminescent signal. Caplostatin suppressed the growth of endometriotic lesions by 59% compared with controls. This novel, noninvasive model of endometriosis provides a means to study early angiogenesis in vivo and to monitor endometriotic growth and the efficacy of systemic antiangiogenic therapy.

A baboon model for endometriosis: implications for fertility

Endometriosis is one of the most common causes of chronic pelvic pain and infertility in women in the reproductive age group. Although the existence of this disease has been known for over 100 years our current knowledge of its pathogenesis and the pathophysiology of its related infertility remains unclear. Several reasons contribute to our lack of knowledge, the most critical being the difficulty in carrying out objective long-term studies in women. Thus, we and others have developed a model of this disease in the non-human primate, the baboon (Papio anubis). Intraperitoneal inoculation of autologous menstrual endometrium results in the development of endometriotic lesions with gross morphological characteristics similar to those seen in the human. Multiple factors have been implicated in endometriosis-associated infertility. We have described aberrant levels of factors involved in multiple pathways important in the establishment of pregnancy, in the endometrium of baboons induced with endometriosis. Specifically, we have observed dysregulation of proteins involved in invasion, angiogenesis, methylation, cell growth, immunomodulation, and steroid hormone action. These data suggest that, in an induced model of endometriosis in the baboon, an increased angiogenic capacity, decreased apoptotic potential, progesterone resistance, estrogen hyper-responsiveness, and an inability to respond appropriately to embryonic signals contribute to the reduced fecundity associated with this disease.