Controlled release of osteopontin and interleukin-10 from modified endovascular coil promote cerebral aneurysm healing

Cerebral Aneurysm and Interleukin-6: a Key Player in Aneurysm Generation and Rupture or Just One of the Multiple Factors?

Intracranial aneurysm (IA) rupture is a common cause of subarachnoid hemorrhage (SAH) with high mortality and morbidity. Inflammatory interleukins (IL), such as IL-6, play an important role in the occurrence and rupture of IA causing SAH. With this review we aim to elucidate the specific role of IL-6 in aneurysm formation and rupture in preclinical and clinical studies. IL-6 is a novel cytokine in that it has pro-inflammatory and anti-inflammatory signaling pathways. In preclinical and clinical studies of IA formation, elevated and reduced levels of IL-6 are reported. Poor post-rupture prognosis and increased rupture risk, however, are associated with higher levels of IL-6. By better understanding the relationships between IL-6 and IA formation and rupture, IL-6 may serve as a biomarker in high-risk populations. Furthermore, by better understanding the IL-6 signaling mechanisms in IA formation and rupture, IL-6 may optimize surveillance and treatment strategies. This review examines the association between IL-6 and IA, while also suggesting future research directions.

Combination release of chemokines from coated coils to target aneurysm healing

BACKGROUND

Monocyte chemoattractant protein 1 (MCP-1) and osteopontin (OPN) have been identified separately as key mediators of the aneurysm healing process following coil embolization in the rodent model. The ability of protein coated coils to accelerate this process is currently unknown.To create coils coated with both MCP-1 and OPN to target aneurysm healing.

METHODS

We uses a polymer (poly(glycolide-co-caprolactone)) (Rao pharmaceuticals) (CG910) to test whether coils could be dual coated with active proteins with sequential reliable release. Coils were coated with poly-DL-lactic glycolic acid (PLGA), CG910, and subsequently dipped with protein OPN (inner layer for delayed release) and MCP-1 (outer layer for initial release). Release assays were used to measure protein elution from coils over time. To test in vivo feasibility, coated coils were implanted into carotid aneurysms to determine the effect on aneurysm healing.

RESULTS

The in vitro protein release assay demonstrated, a significant amount of OPN and MCP-1 release within 2 days. Using a 200 µg/µL solution of MCP-1 in phosphate-buffered saline, we showed that CG910 coated coils provide effective release of MCP over time. In the carotid aneurysm model, MCP-1 and OPN coated coils significantly increased tissue ingrowth (74% and 80%) compared with PLGA and CG910 coated coils alone (58% and 53%). To determine synergistic impact of dual coating, we measured ingrowth for MCP-1/OPN coils (63%) as well as overlap coefficients for NOX4 and NFκB with CD31.

CONCLUSIONS

This study demonstrates that MCP-1 and OPN coated coils are viable and may promote early aneurysm healing. Dual coated coils may have synergistic benefit given different location of protein interaction measured in vivo. Further work is warranted.

Macrophage activation in response to shape memory polymer foam-coated aneurysm occlusion devices

Brain aneurysms can be treated with embolic coils using minimally invasive approaches. It is advantageous to modulate the biologic response of platinum embolic coils. Our previous studies demonstrated that shape memory polymer (SMP) foam coated embolization coils (FCC) devices demonstrate enhanced healing responses in animal models compared with standard bare platinum coil (BPC) devices. Macrophages are the most prevalent immune cell type that coordinate the greater immune response to implanted materials. Hence, we hypothesized that the highly porous SMP foam coatings on embolic coils activate a pro-regenerative healing phenotype. To test this hypothesis, we analyzed the number and type of infiltrating macrophages in FCC or BPC devices implanted in a rabbit elastase aneurysm model. FCC devices elicited a great number of infiltration macrophages, skewed significantly to a pro-regenerative M2-like phenotype 90 days following implantation. We devised an in vitro assay, where monocyte-derived macrophages were placed in close association with FCC or BPC devices for 6-72 h. Macrophages encountering SMP FCC-devices demonstrated highly mixed activation phenotypes at 6 h, heavily skewing toward an M2-like phenotype by 72 h, compared with macrophages encountering BPC devices. Macrophage activation was evaluated using gene expression analysis, and secreted cytokine evaluation. Together, our results demonstrate that FCC devices promoted a pro-regenerative macrophage activation phenotype, compared with BPC devices. Our in vitro findings corroborate with in vivo observations that SMP-based modification of embolic coils can promote better healing of the aneurysm site, by sustaining a pro-healing macrophage phenotype.

The Evolution of Endovascular Therapy for Intracranial Aneurysms: Historical Perspective and Next Frontiers

The history of cerebral aneurysm treatment has a rich and storied past with multiple notable luminaries contributing insights. The modern era has transitioned from primarily clip ligation to increasing use of endovascular therapy. Even more recently, the use of intrasaccular flow diverters has been introduced for the treatment of wide necked aneurysms. The field is continuing to transform, and bioactive coils and stents have resurfaced as promising adjuvants to promote aneurysm healing. Advanced imaging modalities are being developed that could further advance the endovascular arsenal and allow for porous memory polymer devices to enter the field. This focused review highlights notable historic contributions and advances to the point of futuristic technology that is actively being developed.

Mesenchymal stem cells-derived exosomes modulate vascular endothelial injury via miR-144-5p/PTEN in intracranial aneurysm

Phosphatase and tensin homolog (PTEN) is known to be involved in the pathogenesis of intracranial aneurysm (IA). This study investigated the molecular mechanism of exosomal miR-144-5p (ex-miR-144-5p) and PTEN in IA. Ex-miR-144-5p expression was assessed in serum from individuals with ruptured intracranial aneurysm (RA) or unruptured intracranial aneurysm (UA), and healthy controls (HC). Vascular endothelial cells (VECs) were co-cultured with exosomes isolated from mesenchymal stem cells (MSCs) with transfection of miR-144-5p mimic or miR-144-5p inhibitor. IA rats were induced by combing systemic hypertension and intrathecal elastase injection. VECs were transfected with miR-144-5p mimic or inhibitor to verify the impacts of miR-144-5p on cell viability and proliferation. The connection between miR-144-5p and PTEN was verified by luciferase activity assay. Our data proved that ex-miR-144-5p was decreased in both UA and RA patients. MiR-144-5p overexpression in MSCs-derived exosome promoted VEC viability, inhibited VEC proliferation of VEs, and decreased the protein levels of matrix metalloproteinase-9 (MMP-9), proliferating cell nuclear antigen (PCNA) and osteopontin (OPN). IA rats injected with ex-miR-144-5p mimic showed significant luminal dilation, declined smooth muscle layers, and thinned vascular wall. Besides, inhibited cell apoptosis and decreased protein expressions were also observed. However, ex-miR-144-5p inhibitor had the opposite effects both in vivo and in vitro. We validated that miR-144-5p directly targeted PTEN. MiR-144-5p mimic increased cell viability and proliferation and reduced protein expressions, which could be blunted by PTEN overexpression. This study suggests that miR-144-5p elevates PTEN expression, thereby boosting apoptosis and attenuating viability of VECs in IA.

Bioactive refinement for endosaccular treatment of intracranial aneurysms

Endovascular treatment is the first-line therapy for most intracranial aneurysms; however, recanalisation remains a major limitation. Developments in bioengineering and material science have led to a novel generation of coil technologies for aneurysm embolisation that address clinical challenges of aneurysm recurrence. This review presents an overview of modified surface coil technologies and summarises the state of the art regarding their efficacy and limitations based on experimental and clinical results. We also present potential perspectives to develop biologically optimised devices.

The potential biomarkers for the formation and development of intracranial aneurysm

This study is aimed to understand the pathogenesis of intracranial aneurysm (IA), which has a risk of rupture and is the primary cause of subarachnoid hemorrhage. From Gene Expression Omnibus (GEO) database, GSE75436 was extracted (15 IA tissues and 15 superficial temporal artery tissues). The differentially expressed genes (DEGs) was conducted through limma package, which followed by the enrichment analysis. Combining STRING database, protein-protein interaction (PPI) network was constructed. The modules in PPI network were performed utilizing molecular complex detection (MCODE) algorithm. With Cytoscape software, the transcription factor-miRNA-target regulatory network was constructed. Finally, microarray dataset GSE54083 was downloaded (13 IA tissues and 10 superficial temporal artery tissues) for the verification test. A total of 1332 DEGs were screened in IA tissues compared with superficial temporal artery tissues. Besides, the up-regulated TNF, IL10, IL1B, and CTSS, as well as down-regulated IL6 were included in the top 20 nodes in the PPI networks. Furthermore, in the module A of up-regulated PPI network, TNF, IL10, IL1B, and VCAM1 were interact with each other. In the regulatory network, miR-29A/B/C targeted up-regulated genes. Besides, VCAM1 was implicated in the pathway of leukocyte transendothelial migration. In the verification analysis, between GSE75436 and GSE54083, there were 444 up-regulated and 543 down-regulated co-existence DEGs and 11 co-existence genes involved the Leukocyte transendothelial migration pathway. VCAM1, TNF, CTSS, IL10, IL1B, IL6, and miR-29A/B/C might be the potential biomarkers for the formation and development of IA.

Osteopontin as a Link between Inflammation and Cancer: The Thorax in the Spotlight

The glycoprotein osteopontin (OPN) possesses multiple functions in health and disease. To this end, osteopontin has beneficial roles in wound healing, bone homeostasis, and extracellular matrix (ECM) function. On the contrary, osteopontin can be deleterious for the human body during disease. Indeed, osteopontin is a cardinal mediator of tumor-associated inflammation and facilitates metastasis. The purpose of this review is to highlight the importance of osteopontin in malignant processes, focusing on lung and pleural tumors as examples.

Advances in Biomaterials and Technologies for Vascular Embolization

Minimally invasive transcatheter embolization is a common nonsurgical procedure in interventional radiology used for the deliberate occlusion of blood vessels for the treatment of diseased or injured vasculature. A wide variety of embolic agents including metallic coils, calibrated microspheres, and liquids are available for clinical practice. Additionally, advances in biomaterials, such as shape-memory foams, biodegradable polymers, and in situ gelling solutions have led to the development of novel preclinical embolic agents. The aim here is to provide a comprehensive overview of current and emerging technologies in endovascular embolization with respect to devices, materials, mechanisms, and design guidelines. Limitations and challenges in embolic materials are also discussed to promote advancement in the field.

[Roles of macrophages in formation and progression of intracranial aneurysms]

Studies have shown that chronic inflammatory response plays a key role in intracranial aneurysms (IA) formation and progression, and macrophages regulate the formation and progression of IA through a variety of pathways. Bone marrow monocyte-derived macrophages and resident-tissue macrophages infiltrate the vessel wall, after infiltration macrophages are polarized into various polarization phenotypes dominated by M1-like and M2-like cells. Polarized phenotypes of macrophages can regulate the formation and progression of intracranial aneurysms by releasing cytokines and regulating the inflammatory response of other immune cells, as well as release different cytokines to regulate the process of extracellular matrix remodeling. Some important progresses have been made in the clinical detection and treatment in targeting macrophages. This review provides a summary on the pathogenesis of IA and potential drug targets to prevent the formation and rupture of intracranial aneurysms.

Temporal cascade of inflammatory cytokines and cell-type populations in monocyte chemotactic protein-1 (MCP-1)-mediated aneurysm healing

BACKGROUND

We have previously shown that monocyte chemotactic protein-1 (MCP-1) promotes aneurysm healing.

OBJECTIVE

To determine the temporal cascade and durability of aneurysm healing.

METHODS

Murine carotid aneurysms were treated with MCP-1-releasing or poly(lactic-co-glycolic) acid (PLGA)-only coils. Aneurysm healing was assessed by quantitative measurements of intraluminal tissue ingrowth on 5 μm sections by blinded observers.

RESULTS

Aneurysm healing occurred in stages characteristic of normal wound healing. The 1st stage (day 3) was characterized by a spike in neutrophils and T cells. The 2nd stage (week 1) was characterized by an influx of macrophages and CD45+ cells significantly greater with MCP-1 than with PLGA (p<0.05). The third stage (week 2-3) was characterized by proliferation of smooth muscle cells and fibroblasts (greater with MCP-1 than with PLGA, p<0.05). The fourth stage (3-6 months) was characterized by leveling off of smooth muscle cells and fibroblasts. M1 macrophages were greater at week 1, whereas M2 macrophages were greater at weeks 2 and 3 with MCP-1 than with PLGA. Interleukin 6 was present early and increased through week 2 (p<0.05 compared with PLGA) then decreased and leveled off through 6 months. Tumour necrosis factor α was present early and remained constant through 6 months. MCP-1 and PLGA treatment had similar rates of tissue ingrowth at early time points, but MCP-1 had a significantly greater tissue ingrowth at week 3 (p<0.05), which persisted for 6 months.

CONCLUSIONS

The sequential cascade is consistent with an inflammatory model of injury, repair, and remodeling.