An experimental study in the chick embryo chorioallantoic membrane of the anti-angiogenic activity of cyclosporine in rheumatoid arthritis versus osteoarthritis

Tumor grafted - chick chorioallantoic membrane as an alternative model for biological cancer research and conventional/nanomaterial-based theranostics evaluation

Introduction: Advancements in cancer management and treatment are associated with strong preclinical research data, in which reliable cancer models are demanded. Indeed, inconsistent preclinical findings and stringent regulations following the 3Rs principle of reduction, refinement, and replacement of conventional animal models currently pose challenges in the development and translation of efficient technologies. The chick embryo chorioallantoic membrane (CAM) is a system for the evaluation of treatment effects on the vasculature, therefore suitable for studies on angiogenesis. Apart from vascular effects, the model is now increasingly employed as a preclinical cancer model following tumor-grafting procedures.Areas covered: The broad application of CAM tumor model is highlighted along with the methods for analyzing the neoplasm and vascular system. The presented and cited investigations focus on cancer biology and treatment, encompassing both conventional and emerging nanomaterial-based modalities.Expert opinion: The CAM tumor model finds increased significance given the influences of angiogenesis and the tumor microenvironment in cancer behavior, then providing a qualified miniature system for oncological research. Ultimately, the establishment and increased employment of such a model may resolve some of the limitations present in the standard preclinical tumor models, thereby redefining the preclinical research workflow.

An angiogenesis platform using a cubic artificial eggshell with patterned blood vessels on chicken chorioallantoic membrane

The chorioallantoic membrane (CAM) containing tiny blood vessels is an alternative to large animals for studies involving angiogenesis and tissue engineering. However, there is no technique to design the direction of growing blood vessels on the CAM at the microscale level for tissue engineering experiments. Here, a methodology is provided to direct blood vessel formation on the surface of a three-dimensional egg yolk using a cubic artificial eggshell with six functionalized membranes. A structure on the lateral side of the eggshell containing a straight channel and an interlinked chamber was designed, and the direction and formation area of blood vessels with blood flow was artfully defined by channels with widths of 70-2000 μm, without sharply reducing embryo viability. The relationship between the size of interlinked chamber and the induction of blood vessels was investigated to establish a theory of design. Role of negative and positive pressure in the induction of CAM with blood vessels was investigated, and air pressure change in the culture chamber was measured to demonstrate the mechanism for blood vessel induction. Histological evaluation showed that components of CAM including chorionic membrane and blood vessels were induced into the channels. Based on our design theory, blood vessels were induced into arrayed channels, and channel-specific injection and screening were realized, which demonstrated proposed applications. The platform with position- and space-controlled blood vessels is therefore a powerful tool for biomedical research, which may afford exciting applications in studies involved in local stimulation of blood vessel networks and those necessary to establish a living system with blood flow from a beating heart.

Cyclosporin a disrupts notch signaling and vascular lumen maintenance

Cyclosporin A (CSA) suppresses immune function by blocking the cyclophilin A and calcineurin/NFAT signaling pathways. In addition to immunosuppression, CSA has also been shown to have a wide range of effects in the cardiovascular system including disruption of heart valve development, smooth muscle cell proliferation, and angiogenesis inhibition. Circumstantial evidence has suggested that CSA might control Notch signaling which is also a potent regulator of cardiovascular function. Therefore, the goal of this project was to determine if CSA controls Notch and to dissect the molecular mechanism(s) by which CSA impacts cardiovascular homeostasis. We found that CSA blocked JAG1, but not Dll4 mediated Notch1 NICD cleavage in transfected 293T cells and decreased Notch signaling in zebrafish embryos. CSA suppression of Notch was linked to cyclophilin A but not calcineurin/NFAT inhibition since N-MeVal-4-CsA but not FK506 decreased Notch1 NICD cleavage. To examine the effect of CSA on vascular development and function, double transgenic Fli1-GFP/Gata1-RFP zebrafish embryos were treated with CSA and monitored for vasculogenesis, angiogenesis, and overall cardiovascular function. Vascular patterning was not obviously impacted by CSA treatment and contrary to the anti-angiogenic activity ascribed to CSA, angiogenic sprouting of ISV vessels was normal in CSA treated embryos. Most strikingly, CSA treated embryos exhibited a progressive decline in blood flow that was associated with eventual collapse of vascular luminal structures. Vascular collapse in zebrafish embryos was partially rescued by global Notch inhibition with DAPT suggesting that disruption of normal Notch signaling by CSA may be linked to vascular collapse. However, multiple signaling pathways likely cause the vascular collapse phenotype since both cyclophilin A and calcineurin/NFAT were required for normal vascular function. Collectively, these results show that CSA is a novel inhibitor of Notch signaling and vascular function in zebrafish embryos.

Membrane-type I matrix metalloproteinase-dependent regulation of rheumatoid arthritis synoviocyte function

In rheumatoid arthritis, the coordinated expansion of the synoviocyte mass is coupled with a pathologic angiogenic response that leads to the destructive remodeling of articular as well as surrounding connective tissues. Although rheumatoid synoviocytes express a multiplicity of proteolytic enzymes, the primary effectors of cartilage, ligament, and tendon damage remain undefined. Herein, we demonstrate that human rheumatoid synoviocytes mobilize the membrane-anchored matrix metalloproteinase (MMP), membrane-type I MMP (MT1-MMP), to dissolve and invade type I and type II collagen-rich tissues. Though rheumatoid synoviocytes also express a series of secreted collagenases, these proteinases are ineffective in mediating collagenolytic activity in the presence of physiologic concentrations of plasma- or synovial fluid-derived antiproteinases. Furthermore, MT1-MMP not only directs the tissue-destructive properties of rheumatoid synoviocytes but also controls synoviocyte-initiated angiogenic responses in vivo. Together, these findings identify MT1-MMP as a master regulator of the pathologic extracellular matrix remodeling that characterizes rheumatoid arthritis as well as the coupled angiogenic response that maintains the aggressive phenotype of the advancing pannus.

Transcriptional regulation of bone and joint remodeling by NFAT

Osteoporosis and arthritis are highly prevalent diseases and a significant cause of morbidity and mortality worldwide. These diseases result from aberrant tissue remodeling leading to weak, fracture-prone bones or painful, dysfunctional joints. The nuclear factor of activated T cells (NFAT) transcription factor family controls diverse biologic processes in vertebrates. Here, we review the scientific evidence that links NFAT-regulated gene transcription to bone and joint pathology. A particular emphasis is placed on the role of NFATs in bone resorption and formation by osteoclasts and osteoblasts, respectively. In addition, emerging data that connect NFATs with cartilage biology, angiogenesis, nociception, and neurogenic inflammation are explored. The goal of this article is to highlight the importance of tissue remodeling in musculoskeletal disease and situate NFAT-driven cellular responses within this context to inspire future research endeavors.

Increased Expression of Vascular Endothelial Growth Factor in Cyclosporin A-Induced Gingival Overgrowth in Rats

BACKGROUND

Gingival overgrowth is a side effect associated with cyclosporin A (CsA) therapy. The lesion is characterized by increased epithelial thickness, enlargement of connective tissue, and increased vascularization. The aim of this experimental study was to examine the role of vascular endothelial growth factor (VEGF) in the pathogenesis of CsA-induced gingival overgrowth.

METHODS

Twenty male Wistar rats were divided into two groups of 10 animals each. For the development of gingival overgrowth, one group received CsA therapy subcutaneously in a daily dose of 10 mg/kg for 60 days, and the other group was used as a control. At the end of the experimental period, rats were subsequently decapitated, and the mandibles with the surrounding gingiva and soft tissue were removed. Half of each sample was used for histomorphometric analysis, and the other half was used for biochemical analysis. Histomorphometric analysis included the measurements of the number and diameter of blood vessel profiles under a microscope, and biochemical analysis included the assessment of VEGF concentration by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The histomorphometric findings showed that the number of blood vessel profiles increased in the CsA group compared to the control group (P <0.001), although the increase in the diameter of blood vessel profiles was not significant (P >0.05). The biochemical findings showed that in vivo VEGF expression was higher in the CsA group compared to the control group (P <0.001).

CONCLUSION

The results of this study suggest that increased VEGF expression may be associated with the pathogenesis of CsA-induced gingival overgrowth.

Angiogenic response induced by acellular brain scaffolds grafted onto the chick embryo chorioallantoic membrane

The repair and regeneration of injured tissues and organs depend on the re-establishment of the blood flow needed for cellular infiltration and metabolic support. Among the various materials used in tissue reconstruction, acellular scaffolds have recently been utilized. In this study, we investigated the angiogenic response induced by acellular brain scaffolds implanted in vivo onto the chick embryo chorioallantoic membrane (CAM), a useful model for such investigations. The results show that acellular brain scaffolds are able to induce a strong angiogenic response, comparable to that of fibroblast growth factor-2 (FGF-2), a well known angiogenic cytokine. The response may be considered dependent on a direct angiogenic effect exerted by the scaffold, because no inflammatory infiltrate was detectable in CAM's mesenchyme beneath the implant. Acellular brain scaffolds might induce the release of endogenous angiogenic factors, such as FGF-2 and vascular endothelial growth factor (VEGF) released from the extracellular matrix of the developing CAM. In addition, the angiogenic response may depend, in part, also on the presence in the acellular matrix of transforming growth factor beta 1 (TGFbeta1).

Amelioration of cyclosporin A effect on microvasculature by endothelin inhibitor

BACKGROUND

We have previously shown that endothelial injury by cyclosporin A (CyA) is associated with an increased endothelin-1 (ET-1) release. We now sought to determine, in an animal model of angiogenesis, if inhibiting the effect of ET-1 on endothelial cells (ECs) would reverse the CyA-mediated endothelial injury in an animal model of angiogenesis.

METHODS

An angiogenic mixture of Matrigel (0.5 ml), fibroblast growth factor (1 ng/ml), vascular endothelial growth factor (100 ng/ml), and heparin (64 unit/ml) was injected as a subcutaneous plug in the flank of C3H mice (n = 5). In experimental groups CyA (20 mg/ml), CyA, and BQ 123 (ET-A receptor antagonist), CyA and PD 142893 (ET-A and ET-B receptor antagonist), or CyA and ET-1 antibody were added to the angiogenic mixture. Angiogenesis in the mixture was quantified by modified planimetric point counting method in skin/Matrigel cross-sections stained with factor VIII to highlight endothelial neocapillaries. Mean +/- SD of angiogenic area was analyzed with analysis of variance and Bonferroni test. The survival curves obtained by Kaplan-Meier analysis were compared between the groups, and the statistical significance of survival and mortality rates was computed by log rank's and Fisher's exact test, respectively.

RESULTS

The mean +/- SD of angiogenic area in control animals (without CyA in the angiogenic mixture) was 56.76 +/- 4.2. CyA inhibited angiogenesis in the subcutaneous angiogenic plug. Adding CyA to the angiogenic mixture significantly reduced angiogenic area (5.33 +/- 1.4, P <.001) while vehicle for CyA had no such effect (56.33 +/- 3.8, P =.10). Polyclonal ET-1 antibody or PD 142893 ameliorated the effect of CyA, whereas BQ 123 did not. The mean angiogenic areas in animals with ET-1 antibody, PD 142893, or BQ 123 in the angiogenic mixture were 57.20 +/- 7.5 (P =.06), 46.00 +/- 11.5 (P = 1.0), 8.60 +/- 2.9 (P <.001), respectively.

CONCLUSIONS

Our data show that blocking ET-B receptors specifically ameliorates the microvascular injury to the neocapillaries in angiogenesis caused by CyA. Antiendothelin-1 antibody and ETR antagonist (PD 142893) could, therefore, reduce the ill effects of CyA on microvascular endothelium.

A new in vitro model to study endothelial injury

BACKGROUND

Endothelial dysfunction or "endothelialitis" is a prominent feature in several disease states ranging from atherosclerosis to transplant rejection. This dysfunction is also caused by drugs such as cyclosporin A (CyA) and leads to allograft vasculopathy and eventual graft loss. Despite the frequency and importance of this injury, there is no model to study the morphological effects of endothelial injury and dysfunction in vitro.

METHODS

We utilized a model in which mouse endothelial cells (SVEC 4-10) can be induced to form capillary tubes by culturing on a laminin-rich matrix (Matrigel). In this morphological model of endothelial cell function, we studied the effect of varying doses of CyA on two parameters of tube formation: initiation of tube formation and disruption of mature capillary tubes. As a positive control we used IFN-gamma, which inhibited capillary tube formation. We developed this assay in 96-well culture plates to test several samples simultaneously.

RESULTS

The assay could be adapted to a 96-well format by optimizing the cell density. Endothelial dysfunction was seen when the endothelial cells were incubated with cyclosporin A, which affected both morphological parameters of tube formation. At higher doses (2-20 microg/ml) CyA both inhibited capillary tube formation and disrupted mature capillary tubes. At lower doses CyA only inhibited the initiation of tube formation; it did not disrupt mature capillary tubes. IL-2 (400-1000 pg/ml) and IFN-gamma (10-400 pg/ml) inhibited initiation of tube formation but did not disrupt mature capillary tubes. None of these agents, including high doses of CyA, impaired endothelial cell viability.

CONCLUSION

CyA-induced endothelial dysfunction can be modeled in vitro by this novel morphological assay of capillary tube formation. This assay can discern mild and severe degrees of endothelial dysfunction. The different effects of low and high levels of CyA on capillary tube formation imply that similar dysfunction in vivo may be responsible for allograft vasculopathy caused by CyA. This novel model can also be utilized to study other forms of vasculitis.