Matrix metalloproteinase control of capillary morphogenesis

Contribution of immune cells to intervertebral disc degeneration and the potential of immunotherapy

Substantial evidence supports that chronic low back pain is associated with intervertebral disc degeneration (IDD), which is accompanied by decreased cell activity and matrix degradation. The role of immune cells, especially macrophages, in a variety of diseases has been extensively studied; therefore, their role in IDD has naturally attracted widespread scholarly interest. The IVD is considered to be an immunologically-privileged site given the presence of physical and biological barriers that include an avascular microenvironment, a high proteoglycan concentration, high physical pressure, the presence of apoptosis inducers such as Fas ligand, and the presence of notochordal cells. However, during IDD, immune cells with distinct characteristics appear in the IVD. Some of these immune cells release factors that promote the inflammatory response and angiogenesis in the disc and are, therefore, important drivers of IDD. Although some studies have elucidated the role of immune cells, no specific strategies related to systemic immunotherapy have been proposed. Herein, we summarize current knowledge of the presence and role of immune cells in IDD and consider that immunotherapy targeting immune cells may be a novel strategy for alleviating IDD symptoms.

New Perspectives on the Role of Nuclear Proteases in Cell Death Pathways

Multiple factors can trigger cell death via various pathways, and nuclear proteases have emerged as essential regulators of these processes. While certain nuclear proteases have been extensively studied and their mechanisms of action are well understood, others remain poorly characterized. Regulation of nuclear protease activity is a promising therapeutic strategy that could selectively induce favorable cell death pathways in specific tissues or organs. Thus, by understanding the roles of newly discovered or predicted nuclear proteases in cell death processes, we can identify new pharmacological targets for improving therapeutic outcomes. In this article, we delved into the role of nuclear proteases in several types of cell death and explore potential avenues for future research and therapeutic development.

Favorable Biological Performance Regarding the Interaction between Gold Nanoparticles and Mesenchymal Stem Cells

Gold nanoparticles (AuNPs) are well known to interact with cells, leading to different cell behaviors such as cell proliferation and differentiation capacity. Biocompatibility and biological functions enhanced by nanomedicine are the most concerning factors in clinical approaches. In the present research, AuNP solutions were prepared at concentrations of 1.25, 2.5, 5 and 10 ppm for biocompatibility investigations. Ultraviolet-visible spectroscopy was applied to identify the presence of AuNPs under the various concentrations. Dynamic Light Scattering assay was used for the characterization of the size of the AuNPs. The shape of the AuNPs was observed through a Scanning Electron Microscope. Afterward, the mesenchymal stem cells (MSCs) were treated with a differentiation concentration of AuNP solutions in order to measure the biocompatibility of the nanoparticles. Our results demonstrate that AuNPs at 1.25 and 2.5 ppm could significantly enhance MSC proliferation, decrease reactive oxygen species (ROS) generation and attenuate platelet/monocyte activation. Furthermore, the MSC morphology was observed in the presence of filopodia and lamellipodia while being incubated with 1.25 and 2.5 ppm AuNPs, indicating that the adhesion ability was enhanced by the nanoparticles. The expression of matrix metalloproteinase (MMP-2/9) in MSCs was found to be more highly expressed under 1.25 and 2.5 ppm AuNP treatment, relating to better cell migrating ability. Additionally, the cell apoptosis of MSCs investigated with Annexin-V/PI double staining assay and the Fluorescence Activated Cell Sorting (FACS) method demonstrated the lower population of apoptotic cells in 1.25 and 2.5 ppm AuNP treatments, as compared to high concentrations of AuNPs. Additionally, results from a Western blotting assay explored the possibility that the anti-apoptotic proteins Cyclin-D1 and Bcl-2 were remarkably expressed. Meanwhile, real-time PCR analysis demonstrated that the 1.25 and 2.5 ppm AuNP solutions induced a lower expression of inflammatory cytokines (TNF-α, IL-1β, IFN-γ, IL-6 and IL-8). According to the tests performed on an animal model, AuNP 1.25 and 2.5 ppm treatments exhibited the better biocompatibility performance, including anti-inflammation and endothelialization. In brief, 1.25 and 2.5 ppm of AuNP solution was verified to strengthen the biological functions of MSCs, and thus suggests that AuNPs become the biocompatibility nanomedicine for regeneration research.

Insights Into the Role of Matrix Metalloproteinases in Cancer and its Various Therapeutic Aspects: A Review

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that regulate the turnover of extracellular matrix (ECM) components. Gross and La Piere discovered MMPs in 1962 during an experiment on tissue samples from a tadpole’s tail. Several subtypes of MMPs have been identified, depending on their substrate specificity and localization. MMPs are involved as essential molecules in multiple and diverse physiological processes, such as reproduction, embryonic development, bone remodeling, tissue repair, and regulation of inflammatory processes. Its activity is controlled at various levels such as at transcription level, pro-peptide activation level and by the activity of a family of tissue inhibitors of metalloproteinase, endogenous inhibitors of MMPs. Cancer metastasis, which is the spread of a tumor to a distant site, is a complex process that is responsible for the majority of cancer-related death It is considered to be an indicator of cancer metastasis. During metastasis, the tumor cells have to invade the blood vessel and degrade the ECM to make a path to new loci in distant places. The degradation of blood vessels and ECM is mediated through the activity of MMPs. Hence, the MMP activity is critical to determining the metastatic potential of a cancer cell. Evasion of apoptosis is one of the hallmarks of cancer that are found to be correlated with the expression of MMPs. As a result, given the importance of MMPs in cancer, we describe the role of these multifunctional enzymes MMPs in various aspects of cancer formation and their rising possibilities as a novel therapeutic target in this review. There is also a brief discussion of various types of therapeutic components and drugs that function against MMPs.

Microfluidic Electroceuticals Platform for Therapeutic Strategies of Intervertebral Disc Degeneration: Effects of Electrical Stimulation on Human Nucleus Pulposus Cells under Inflammatory Conditions

The degeneration of an intervertebral disc (IVD) is a major cause of lower back pain. IVD degeneration is characterized by the abnormal expression of inflammatory cytokines and matrix degradation enzymes secreted by IVD cells. In addition, macrophage-mediated inflammation is strongly associated with IVD degeneration. However, the precise pathomechanisms of macrophage-mediated inflammation in IVD are still unknown. In this study, we developed a microfluidic platform integrated with an electrical stimulation (ES) array to investigate macrophage-mediated inflammation in human nucleus pulposus (NP). This platform provides multiple cocultures of different cell types with ES. We observed macrophage-mediated inflammation and considerable migration properties via upregulated expression of interleukin (IL)-6 (p < 0.001), IL-8 (p < 0.05), matrix metalloproteinase (MMP)-1 (p < 0.05), and MMP-3 (p < 0.05) in human NP cells cocultured with macrophages. We also confirmed the inhibitory effects of ES at 10 μA due to the production of IL-6 (p < 0.05) and IL-8 (p < 0.01) under these conditions. Our findings indicate that ES positively affects degenerative inflammation in diverse diseases. Accordingly, the microfluidic electroceutical platform can serve as a degenerative IVD inflammation in vitro model and provide a therapeutic strategy for electroceuticals.

Comparison of the Behavior of Perivascular Cells (Pericytes and CD34+ Stromal Cell/Telocytes) in Sprouting and Intussusceptive Angiogenesis

Perivascular cells in the pericytic microvasculature, pericytes and CD34+ stromal cells/telocytes (CD34+SCs/TCs), have an important role in angiogenesis. We compare the behavior of these cells depending on whether the growth of endothelial cells (ECs) from the pre-existing microvasculature is toward the interstitium with vascular bud and neovessel formation (sprouting angiogenesis) or toward the vascular lumen with intravascular pillar development and vessel division (intussusceptive angiogenesis). Detachment from the vascular wall, mobilization, proliferation, recruitment, and differentiation of pericytes and CD34+SCs/TCs, as well as associated changes in vessel permeability and functionality, and modifications of the extracellular matrix are more intense, longer lasting over time, and with a greater energy cost in sprouting angiogenesis than in intussusceptive angiogenesis, in which some of the aforementioned events do not occur or are compensated for by others (e.g., sparse EC and pericyte proliferation by cell elongation and thinning). The governing mechanisms involve cell-cell contacts (e.g., peg-and-socket junctions between pericytes and ECs), multiple autocrine and paracrine signaling molecules and pathways (e.g., vascular endothelial growth factor, platelet-derived growth factor, angiopoietins, transforming growth factor B, ephrins, semaphorins, and metalloproteinases), and other factors (e.g., hypoxia, vascular patency, and blood flow). Pericytes participate in vessel development, stabilization, maturation and regression in sprouting angiogenesis, and in interstitial tissue structure formation of the pillar core in intussusceptive angiogenesis. In sprouting angiogenesis, proliferating perivascular CD34+SCs/TCs are an important source of stromal cells during repair through granulation tissue formation and of cancer-associated fibroblasts (CAFs) in tumors. Conversely, CD34+SCs/TCs have less participation as precursor cells in intussusceptive angiogenesis. The dysfunction of these mechanisms is involved in several diseases, including neoplasms, with therapeutic implications.

Matrix Metalloproteinase 10 Contributes to Choroidal Neovascularisation

Age-related macular degeneration (AMD) is currently the main cause of severe visual loss among older adults in developed countries. The pathophysiology has not been clarified, but oxidative stress is believed to play a major role. Matrix metalloproteinases (MMP) may play a prominent role in several steps of the pathophysiology of AMD, especially in its neovascular form; therefore, there is of great interest in understanding their role in choroidal neovascularisation. This study aimed to elucidate the role of MMP10 in the development of choroidal neovascularisation (CNV). We have demonstrated that MMP10 was expressed by retinal pigment epithelium cells and endothelial cells of the neovascular membrane, in cell culture, mouse and human retina. MMP10 expression and activity increased under oxidative stress conditions in ARPE-19 cells. MMP10-/- mice developed smaller laser-induced areas of CNV. Furthermore, to exclude a systemic MMP10 imbalance in these patients, plasma MMP10 concentrations were assessed in an age- and sex-matched sample of 52 control patients and 52 patients with neovascular AMD and no significant differences were found between the groups, demonstrating that MMP10 induction is a local phenomenon. Our findings suggest that MMP10 participates in the development of choroidal neovascularisation and promotes MMP10 as a possible new therapeutic target.

Endoglin Modulates TGFβR2 Induced VEGF and Proinflammatory Cytokine Axis Mediated Angiogenesis in Prolonged DEHP-Exposed Breast Cancer Cells

Angiogenesis is the process of vascular network development and plays a crucial role in cancer growth, progression, and metastasis. Phthalates are a class of environmental pollutants that have detrimental effects on human health and are reported to increase cancer risk. However, the interplay between phthalate exposure and angiogenesis has not been investigated thoroughly. In this study, we investigated the effect of prolonged di (2-ethylhexyl) phthalate (DEHP) treatment on the angiogenic potential of triple-negative breast cancer. MDA-MB-231 cells were exposed to physiological concentrations of DEHP for more than three months. Prolonged DEHP exposure induced angiogenesis in breast cancer cells. Endoglin (ENG)/CD105 is a membrane glycoprotein and an auxiliary receptor of the TGFβ receptor complex. In endothelial cells, ENG is highly expressed and it is a prerequisite for developmental angiogenesis. A literature review highlights endoglin as a well-known mesenchymal stem cell marker responsible for vascular development and angiogenesis. NGS analysis showed that endoglin overexpression in DEHP-exposed MDA-MB-231 cells correlated with tumor development and growth. An in vivo zebrafish xenograft assay showed that VEGFA induced sprouting of the subintestinal vein (SIV) in embryos injected with DEHP-exposed cells. Endoglin knockdown reduced SIV sprouting and VEGFA expression in zebrafish embryos. An in vitro HUVEC tube formation assay showed that endoglin depletion reversed DEHP-induced VEGF-mediated HUVEC tube formation in coculture. DEHP-induced endoglin activated TGFβ/SMAD3/VEGF and MAPK/p38 signaling in MDA-MB-231 cells. A cytokine angiogenesis antibody array showed induced expression of the inflammatory cytokines IL1α, IL1β, IL6, and IL8, along with GMCSF and VEGF. Endoglin knockdown reversed DEHP-induced activation of the TGFβ/SMAD3/VEGF signaling axis, MAPK/p38 signaling, and cytokine regulation, limiting angiogenesis potential both in vivo and in vitro. Targeting endoglin might serve as a potential alternative treatment to control angiogenesis, leading to metastasis and limiting cancer progression.

HSP90 as a regulator of extracellular matrix dynamics

The extracellular matrix (ECM) is a dynamic and organised extracellular network assembled from proteins and carbohydrates exported from the cell. The ECM is critical for multicellular life, providing spatial and temporal cellular cues to maintain tissue homeostasis. Consequently, ECM production must be carefully balanced with turnover to ensure homeostasis; ECM dysfunction culminates in disease. Hsp90 is a molecular chaperone central to protein homeostasis, including in the ECM. Intracellular and extracellular Hsp90 isoforms collaborate to regulate the levels and status of proteins in the ECM via multiple mechanisms. In so doing, Hsp90 regulates ECM dynamics, and changes in Hsp90 levels or activity support the development of ECM-related diseases, like cancer and fibrosis. Consequently, Hsp90 levels may have prognostic value, while inhibition of Hsp90 may have therapeutic potential in conditions characterised by ECM dysfunction.

Selected Biomarkers of Tick-Borne Encephalitis: A Review

Tick-borne encephalitis (TBE) is an acute disease caused by the tick-borne encephalitis virus. Due to the viral nature of the condition, there is no effective causal treatment for full-blown disease. Current and nonspecific TBE treatments only relieve symptoms. Unfortunately, the first phase of TBE is characterized by flu-like symptoms, making diagnosis difficult during this period. The second phase is referred to as the neurological phase as it involves structures in the central nervous system-most commonly the meninges and, in more severe cases, the brain and the spinal cord. Therefore, it is important that early markers of TBE that will guide clinical decision-making and the choice of treatment are established. In this review, we performed an extensive search of literature reports relevant to biomarkers associated with TBE using the MEDLINE/PubMed database. We observed that apart from routinely determined specific immunoglobulins, free light chains may also be useful in the evaluation of intrathecal synthesis in the central nervous system (CNS) during TBEV infection. Moreover, selected metalloproteinases, chemokines, or cytokines appear to play an important role in the pathogenesis of TBE as a consequence of inflammatory reactions and recruitment of white blood cells into the CNS. Furthermore, we reported promising findings on tau protein or Toll-like receptors. It was also observed that some people may be predisposed to TBE. Therefore, to understand the role of selected tick-borne encephalitis biomarkers, we categorized these factors and discussed their potential application in the diagnosis, prognosis, monitoring, or management of TBE.

Normalizing Tumor Vasculature to Reduce Hypoxia, Enhance Perfusion, and Optimize Therapy Uptake

Simple Summary

In order for solid tumors to grow, they need to develop new blood vessels in order to support their increasing metabolic requirements. To facilitate the novel vessel formation, the tumor initiates an aggressive pro-angiogenic program. As a result of the aggressive angiogenesis, blood vessels form very rapidly and are often malformed and dysfunctional. There is a reduction in perfusion to the tumor, and often the tumors exhibit significant areas of tumor hypoxia. This review paper discusses the pro-tumorigenic environment induced by tumor hypoxia and how this can be targeted through normalization of the tumor vasculature. Here, we review tumor angiogenesis, the development of a hypoxic phenotype, and how this contributes to sustained tumorigenesis and resistance to therapy. We further discuss the potential of vascular normalization to reduce tumor hypoxia and facilitate uptake and efficacy of a variety of therapies.

Abstract

A basic requirement of tumorigenesis is the development of a vascular network to support the metabolic requirements of tumor growth and metastasis. Tumor vascular formation is regulated by a balance between promoters and inhibitors of angiogenesis. Typically, the pro-angiogenic environment created by the tumor is extremely aggressive, resulting in the rapid vessel formation with abnormal, dysfunctional morphology. The altered morphology and function of tumor blood and lymphatic vessels has numerous implications including poor perfusion, tissue hypoxia, and reduced therapy uptake. Targeting tumor angiogenesis as a therapeutic approach has been pursued in a host of different cancers. Although some preclinical success was seen, there has been a general lack of clinical success with traditional anti-angiogenic therapeutics as single agents. Typically, following anti-angiogenic therapy, there is remodeling of the tumor microenvironment and widespread tumor hypoxia, which is associated with development of therapy resistance. A more comprehensive understanding of the biology of tumor angiogenesis and insights into new clinical approaches, including combinations with immunotherapy, are needed to advance vascular targeting as a therapeutic area.

Anti-Inflammatory Fibronectin-AgNP for Regulation of Biological Performance and Endothelial Differentiation Ability of Mesenchymal Stem Cells

The engineering of vascular regeneration still involves barriers that need to be conquered. In the current study, a novel nanocomposite comprising of fibronectin (denoted as FN) and a small amount of silver nanoparticles (AgNP, ~15.1, ~30.2 or ~75.5 ppm) was developed and its biological function and biocompatibility in Wharton's jelly-derived mesenchymal stem cells (MSCs) and rat models was investigated. The surface morphology as well as chemical composition for pure FN and the FN-AgNP nanocomposites incorporating various amounts of AgNP were firstly characterized by atomic force microscopy (AFM), UV-Visible spectroscopy (UV-Vis), and Fourier-transform infrared spectroscopy (FTIR). Among the nanocomposites, FN-AgNP with 30.2 ppm silver nanoparticles demonstrated the best biocompatibility as assessed through intracellular ROS production, proliferation of MSCs, and monocytes activation. The expression levels of pro-inflammatory cytokines, TNF-α, IL-1β, and IL-6, were also examined. FN-AgNP 30.2 ppm significantly inhibited pro-inflammatory cytokine expression compared to other materials, indicating superior performance of anti-immune response. Mechanistically, FN-AgNP 30.2 ppm significantly induced greater expression of vascular endothelial growth factor (VEGF) and stromal-cell derived factor-1 alpha (SDF-1α) and promoted the migration of MSCs through matrix metalloproteinase (MMP) signaling pathway. Besides, in vitro and in vivo studies indicated that FN-AgNP 30.2 ppm stimulated greater protein expressions of CD31 and von Willebrand Factor (vWF) as well as facilitated better endothelialization capacity than other materials. Furthermore, the histological tissue examination revealed the lowest capsule formation and collagen deposition in rat subcutaneous implantation of FN-AgNP 30.2 ppm. In conclusion, FN-AgNP nanocomposites may facilitate the migration and proliferation of MSCs, induce endothelial cell differentiation, and attenuate immune response. These finding also suggests that FN-AgNP may be a potential anti-inflammatory surface modification strategy for vascular biomaterials.

Collagen biology making inroads into prognosis and treatment of cancer progression and metastasis

Progression through dissemination to tumor-surrounding tissues and metastasis development is a hallmark of cancer that requires continuous cell-to-cell interactions and tissue remodeling. In fact, metastization can be regarded as a tissue disease orchestrated by cancer cells, leading to neoplastic colonization of new organs. Collagen is a major component of the extracellular matrix (ECM), and increasing evidence suggests that it has an important role in cancer progression and metastasis. Desmoplasia and collagen biomarkers have been associated with relapse and death in cancer patients. Despite the increasing interest in ECM and in the desmoplastic process in tumor microenvironment as prognostic factors and therapeutic targets in cancer, further research is required for a better understanding of these aspects of cancer biology. In this review, published evidence correlating collagen with cancer prognosis is retrieved and analyzed, and the role of collagen and its fragments in cancer pathophysiology is discussed.

In vitro model of distinct catabolic and inflammatory response patterns of endothelial cells to intervertebral disc cell degeneration

To evaluate dominant cell-to-cell paracrine interactions, including those of human annulus fibrosus (AF), nucleus pulposus (NP), and endothelial cells (ECs), in the production of inflammatory mediators and catabolic enzymes, ECs was cultured in soluble factors derived from AF or NP cells (AFCM or NPCM, respectively) and vice versa. We analysed IL-6 and -8, vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-1 and -3, nerve growth factor (NGF)-β, and brain-derived neurotrophic factors (BDNFs) with qRT-PCR and ELISA. We implement a microfluidic platform to analyse migration properties of AF and NP cells and ECs in 3D cultures. Our results show that IL-1β-stimulated AF cells produced significantly higher levels of IL-6 and -8, VEGF, and MMP-1 than IL-1β-stimulated NP cells. However, production of IL-6 and -8, VEGF, and MMP-3 was significantly higher in NP cells than in AF cells, under the presence of ECs conditioned medium. We observed considerable migration of NP cells co-cultured with ECs through the microfluidic platform. These results suggest that AF cells may play a major role in the initial degeneration of intervertebral disc. Furthermore, it was found that interactions between NP cells and ECs may play a significant role in the development or progression of diseases.

Cysteine cathepsins are altered by flow within an engineered in vitro microvascular niche

Throughout the process of vascular growth and remodeling, the extracellular matrix (ECM) concurrently undergoes significant changes due to proteolytic activity—regulated by both endothelial and surrounding stromal cells. The role of matrix metalloproteinases has been well-studied in the context of vascular remodeling, but other proteases, such as cysteine cathepsins, could also facilitate ECM remodeling. To investigate cathepsin-mediated proteolysis in vascular ECM remodeling, and to understand the role of shear flow in this process, in vitro microvessels were cultured in previously designed microfluidic chips and assessed by immunostaining, zymography, and western blotting. Primary human vessels (HUVECs and fibroblasts) were conditioned by continuous fluid flow and/or small molecule inhibitors to probe cathepsin expression and activity. Luminal flow (in contrast to static culture) decreases the activity of cathepsins in microvessel systems, despite a total protein increase, due to a concurrent increase in the endogenous inhibitor cystatin C. Observations also demonstrate that cathepsins mostly co-localize with fibroblasts, and that fibrin (the hydrogel substrate) may stabilize cathepsin activity in the system. Inhibitor studies suggest that control over cathepsin-mediated ECM remodeling could contribute to improved maintenance of in vitro microvascular networks; however, further investigation is required. Understanding the role of cathepsin activity in in vitro microvessels and other engineered tissues will be important for future regenerative medicine applications.

Angiogenic biomaterials to promote therapeutic regeneration and investigate disease progression

The vasculature is a key component of the tissue microenvironment. Traditionally known for its role in providing nutrients and oxygen to surrounding cells, the vasculature is now also acknowledged to provide signaling cues that influence biological outcomes in regeneration and disease. These cues come from the cells that comprise vasculature, as well as the dynamic biophysical and biochemical properties of the surrounding extracellular matrix that accompany vascular development and remodeling. In this review, we illustrate the larger role of the vasculature in the context of regenerative biology and cancer progression. We describe cellular, biophysical, biochemical, and metabolic components of vascularized microenvironments. Moreover, we provide an overview of multidimensional angiogenic biomaterials that have been developed to promote therapeutic vascularization and regeneration, as well as to mimic elements of vascularized microenvironments as a means to uncover mechanisms by which vasculature influences cancer progression and therapy.

Cellular Based Strategies for Microvascular Engineering

Vascularization is a major hurdle in complex tissue and organ engineering. Tissues greater than 200 μm in diameter cannot rely on simple diffusion to obtain nutrients and remove waste. Therefore, an integrated vascular network is required for clinical translation of engineered tissues. Microvessels have been described as <150 μm in diameter, but clinically they are defined as <1 mm. With new advances in super microsurgery, vessels less than 1 mm can be anastomosed to the recipient circulation. However, this technical advancement still relies on the creation of a stable engineered microcirculation that is amenable to surgical manipulation and is readily perfusable. Microvascular engineering lays on the crossroads of microfabrication, microfluidics, and tissue engineering strategies that utilize various cellular constituents. Early research focused on vascularization by co-culture and cellular interactions, with the addition of angiogenic growth factors to promote vascular growth. Since then, multiple strategies have been utilized taking advantage of innovations in additive manufacturing, biomaterials, and cell biology. However, the anatomy and dynamics of native blood vessels has not been consistently replicated. Inconsistent results can be partially attributed to cell sourcing which remains an enigma for microvascular engineering. Variations of endothelial cells, endothelial progenitor cells, and stem cells have all been used for microvascular network fabrication along with various mural cells. As each source offers advantages and disadvantages, there continues to be a lack of consensus. Furthermore, discord may be attributed to incomplete understanding about cell isolation and characterization without considering the microvascular architecture of the desired tissue/organ.

Endothelial Cells in the Tumor Microenvironment

Angiogenesis is a critical process required for tumor progression. Newly formed blood vessels provide nutrition and oxygen to the tumor contributing to its growth and development. However, endothelium also plays other functions that promote tumor metastasis. It is involved in intravasation, which allows invasive cancer cells to translocate into the blood vessel lumen. This phenomenon is an important stage for cancer metastasis. Besides direct association with cancer development, endothelial cells are one of the main sources of cancer-associated fibroblasts (CAFs). The heterogeneous group of CAFs is the main inductor of migration and invasion abilities of cancer cells. Therefore, the endothelium is also indirectly responsible for metastasis. Considering the above, the endothelium is one of the important targets of anticancer therapy. In the chapter, we will present mechanisms regulating endothelial function, dependent on cancer and cancer niche cells. We will focus on possibilities of suppressing pro-metastatic endothelial functions, applied in anti-cancer therapies.

Cell-mediated matrix stiffening accompanies capillary morphogenesis in ultra-soft amorphous hydrogels

There is a critical need for biomaterials that support robust neovascularization for a wide-range of clinical applications. Here we report how cells alter tissue-level mechanical properties during capillary morphogenesis using a model of endothelial-stromal cell co-culture within poly(ethylene glycol) (PEG) based hydrogels. After a week of culture, we observed substantial stiffening in hydrogels with very soft initial properties. Endothelial cells or stromal cells alone, however, failed to induce hydrogel stiffening. This stiffening tightly correlated with degree of vessel formation but not with hydrogel compaction or cellular proliferation. Despite a lack of fibrillar architecture within the PEG hydrogels, cell-generated contractile forces were essential for hydrogel stiffening. Upregulation of alpha smooth muscle actin and collagen-1 was also correlated with enhanced vessel formation and hydrogel stiffening. Blocking cell-mediated hydrogel degradation abolished stiffening, demonstrating that matrix metalloproteinase (MMP)-mediated remodeling is required for stiffening to occur. These results highlight the dynamic reciprocity between cells and their mechanical microenvironment during capillary morphogenesis and provide important insights for the rational design of materials for vasculogenic applications.

Deciphering the relative roles of matrix metalloproteinase- and plasmin-mediated matrix degradation during capillary morphogenesis using engineered hydrogels

Extracellular matrix (ECM) remodeling is essential for the process of capillary morphogenesis. Here we employed synthetic poly(ethylene glycol) (PEG) hydrogels engineered with proteolytic specificity to either matrix metalloproteinases (MMPs), plasmin, or both to investigate the relative contributions of MMP- and plasmin-mediated ECM remodeling to vessel formation in a 3D-model of capillary self-assembly analogous to vasculogenesis. We first demonstrated a role for both MMP- and plasmin-mediated mechanisms of ECM remodeling in an endothelial-fibroblast co-culture model of vasculogenesis in fibrin hydrogels using inhibitors of MMPs and plasmin. When this co-culture model was employed in engineered PEG hydrogels with selective protease sensitivity, we observed robust capillary morphogenesis only in MMP-sensitive matrices. Fibroblast spreading in plasmin-selective hydrogels confirmed this difference was due to protease preference by endothelial cells, not due to limitations of the matrix itself. In hydrogels engineered with crosslinks that were dually susceptible to MMPs and plasmin, capillary morphogenesis was unchanged. These findings highlight the critical importance of MMP-mediated degradation during vasculogenesis and provide strong evidence to justify the preferential selection of MMP-degradable peptide crosslinkers in synthetic hydrogels used to study vascular morphogenesis and promote vascularization. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2507-2516, 2019.

Mechanisms of Action of Novel Drugs Targeting Angiogenesis-Promoting Matrix Metalloproteinases

Angiogenesis is facilitated by the proteolytic activities of members of the matrix metalloproteinase (MMP) family. More specifically, MMP-9 and MT1-MMP directly regulate angiogenesis, while several studies indicate a role for MMP-2 as well. The correlation of MMP activity to tumor angiogenesis has instigated numerous drug development programs. However, broad-based and Zn²⁺-chelating MMP inhibitors have fared poorly in the clinic. Selective MMP inhibition by antibodies, biologicals, and small molecules has utilized unique modes of action, such as (a) binding to protease secondary binding sites (exosites), (b) allosterically blocking the protease active site, or (c) preventing proMMP activation. Clinical trials have been undertaken with several of these inhibitors, while others are in advanced pre-clinical stages. The mechanistically non-traditional MMP inhibitors offer treatment strategies for tumor angiogenesis that avoid the off-target toxicities and lack of specificity that plagued Zn²⁺-chelating inhibitors.

Aneurysmal bone cyst treated with percutaneous doxycycline: is a single treatment sufficient?

OBJECTIVE

The purpose of this case series is to report on the effectiveness of a single percutaneous injection of doxycycline as a primary treatment for aneurysmal bone cyst (ABC).

MATERIALS AND METHODS

A retrospective cohort study was conducted on seven patients diagnosed with ABC at various anatomical sites, with the intention to treat by a single percutaneous injection of doxycycline. Mean patient age was 14 years.

RESULTS

Signs of treatment response were seen in six of seven patients after one injection. Three of the seven received a second treatment, despite signs of response. Another had expansion of the lesion after treatment, requiring excision. In total, three patients had a single injection of doxycycline as their sole treatment and another three showed signs of response after a single injection.

CONCLUSIONS

A single percutaneous injection of doxycycline should be considered a viable primary treatment option for ABC.

Angiogenic Self-Assembling Peptide Scaffolds for Functional Tissue Regeneration

Implantation of acellular biomimetic scaffolds with proangiogenic motifs may have exciting clinical utility for the treatment of ischemic pathologies such as myocardial infarction. Although direct delivery of angiogenic proteins is a possible treatment option, smaller synthetic peptide-based nanostructured alternatives are being investigated due to favorable factors, such as sustained efficacy and high-density epitope presentation of functional moieties. These peptides may be implanted in vivo at the site of ischemia, bypassing the first-pass metabolism and enabling long-term retention and sustained efficacy. Mimics of angiogenic proteins show tremendous potential for clinical use. We discuss possible approaches to integrate the functionality of such angiogenic peptide mimics into self-assembled peptide scaffolds for application in functional tissue regeneration.

Restoring vasculogenic potential of endothelial cells from diabetic patients through spheroid formation

Introduction

Diabetes is an emerging epidemic in the developing world and represents a major risk factor for cardiovascular disease. Among other issues, patients with diabetes suffer from diminished endothelial cell (EC) function, which contributes to impaired vasculogenesis and recovery from ischemic insult. The formation of cells into three-dimensional spheroids promotes cell survival and activates key signaling pathways through the upregulation of cell-cell contacts, providing an opportunity to overcome shortcomings associated with individual autologous cells.

Methods

We hypothesized that forming human microvascular endothelial cells (HMVECs) from diabetic patients into spheroids would restore their vasculogenic potential following upregulation of these cell-cell interactions. HMVEC spheroids were formed and suspended in fibrin gels to quantify vasculogenic potential.

Results

Individual HMVECs from diabetic patients exhibited similar proliferative and chemotactic potential to cells from healthy donors but reduced tubulogenesis. HMVEC spheroids formed from diabetic donors formed more sprouts than spheroids from healthy donors, and more sprouts than individual cells from either population.

Conclusions

Compared to cells from healthy donors, sprout formation was more efficiently abrogated in HMVECs from diabetic patients by blocking matrix metalloproteinase activity. This study demonstrates a promising approach for restoring the diminished vasculogenic potential of endothelial cells in diabetic patients.

Evaluating the potential of endothelial cells derived from human induced pluripotent stem cells to form microvascular networks in 3D cultures

A major translational challenge in the fields of therapeutic angiogenesis and regenerative medicine is the need to create functional microvasculature. The purpose of this study was to assess whether a potentially autologous endothelial cell (EC) source derived from human induced pluripotent stem cells (iPSC-ECs) can form the same robust, stable microvasculature as previously documented for other sources of ECs. We utilized a well-established in vitro assay, in which endothelial cell-coated (iPSC-EC or HUVEC) beads were co-embedded with fibroblasts in a 3D fibrin matrix to assess their ability to form stable microvessels. iPSC-ECs exhibited a five-fold reduction in capillary network formation compared to HUVECs. Increasing matrix density reduced sprouting, although this effect was attenuated by distributing the NHLFs throughout the matrix. Inhibition of both MMP- and plasmin-mediated fibrinolysis was required to completely block sprouting of both HUVECs and iPSC-ECs. Further analysis revealed MMP-9 expression and activity were significantly lower in iPSC-EC/NHLF co-cultures than in HUVEC/NHLF co-cultures at later time points, which may account for the observed deficiencies in angiogenic sprouting of the iPSC-ECs. Collectively, these findings suggest fundamental differences in EC phenotypes must be better understood to enable the promise and potential of iPSC-ECs for clinical translation to be realized.

Growth factor sequestration and enzyme-mediated release from genipin-crosslinked gelatin microspheres

Controlled release of growth factors allows the efficient, localized, and temporally-optimized delivery of bioactive molecules to potentiate natural physiological processes. This concept has been applied to treatments for pathological states, including chronic degeneration, wound healing, and tissue regeneration. Peptide microspheres are particularly suited for this application because of their low cost, ease of manufacture, and interaction with natural remodeling processes active during healing. The present study characterizes gelatin microspheres for the entrapment and delivery of growth factors, with a focus on tailored protein affinity, loading capacity, and degradation-mediated release. Genipin crosslinking in PBS and CHES buffers produced average microsphere sizes ranging from 15 to 30 microns with population distributions ranging from about 15 to 60 microns. Microsphere formulations were chosen based on properties important for controlled transient and spatial delivery, including size, consistency, and stability. The microsphere charge affinity was found to be dependent on gelatin type, with type A (GelA) carriers consistently having a lower negative charge than equivalent type B (GelB) carriers. A higher degree of crosslinking, representative of primary amine consumption, resulted in a greater negative net charge. Gelatin type was found to be the strongest determinant of degradation, with GelA carriers degrading at higher rates versus similarly crosslinked GelB carriers. Growth factor release was shown to depend upon microsphere degradation by proteolytic enzymes, while microspheres in inert buffers showed long-term retention of growth factors. These studies illuminate fabrication and processing parameters that can be used to control spatial and temporal release of growth factors from gelatin-based microspheres.

MMP proteolytic activity regulates cancer invasiveness by modulating integrins

Cancer invasion through dense extracellular matrices (ECMs) is mediated by matrix metalloproteinases (MMPs) which degrade the ECM thereby creating paths for migration. However, how this degradation influences the phenotype of cancer cells is not fully clear. Here we address this question by probing the function of MMPs in regulating biophysical properties of cancer cells relevant to invasion. We show that MMP catalytic activity regulates cell spreading, motility, contractility and cortical stiffness by stabilizing integrins at the membrane and activating focal adhesion kinase. Interestingly, cell rounding and cell softening on stiff gels induced by MMP inhibition is attenuated on MMP pre-conditioned surfaces. Together, our results suggest that MMP catalytic activity regulates invasiveness of cancer cells by modulating integrins.

The pVHL172 isoform is not a tumor suppressor and up-regulates a subset of pro-tumorigenic genes including TGFB1 and MMP13

The von Hippel-Lindau (VHL) tumor suppressor gene is often deleted or mutated in ccRCC (clear cell renal cell carcinoma) producing a non-functional protein. The gene encodes two mRNA, and three protein isoforms (pVHL₂₁₃, pVHL₁₆₀ and pVHL₁₇₂). The pVHL protein is part of an E3 ligase complex involved in the ubiquitination and proteasomal degradation of different proteins, particularly hypoxia inducible factors (HIF) that drive the transcription of genes involved in the regulation of cell proliferation, angiogenesis or extracellular matrix remodelling. Other non-canonical (HIF-independent) pVHL functions have been described. A recent work reported the expression of the uncharacterized protein isoform pVHL₁₇₂ which is translated from the variant 2 by alternative splicing of the exon 2. This splice variant is sometimes enriched in the ccRCCs and the protein has been identified in the respective samples of ccRCCs and different renal cell lines. Functional studies on pVHL have only concerned the pVHL₂₁₃ and pVHL₁₆₀ isoforms, but no function was assigned to pVHL₁₇₂. Here we show that pVHL₁₇₂ stable expression in renal cancer cells does not regulate the level of HIF, exacerbates tumorigenicity when 786-O-pVHL₁₇₂ cells were xenografted in mice. The pVHL₁₇₂-induced tumors developed a sarcomatoid phenotype. Moreover, pVHL₁₇₂ expression was shown to up regulate a subset of pro-tumorigenic genes including TGFB1, MMP1 and MMP13. In summary we identified that pVHL₁₇₂ is not a tumor suppressor. Furthermore our findings suggest an antagonistic function of this pVHL isoform in the HIF-independent aggressiveness of renal tumors compared to pVHL₂₁₃.

Angiogenesis in the atherosclerotic plaque

Atherosclerosis is a multifocal alteration of the vascular wall of medium and large arteries characterized by a local accumulation of cholesterol and non-resolving inflammation. Atherothrombotic complications are the leading cause of disability and mortality in western countries. Neovascularization in atherosclerotic lesions plays a major role in plaque growth and instability. The angiogenic process is mediated by classical angiogenic factors and by additional factors specific to atherosclerotic angiogenesis. In addition to its role in plaque progression, neovascularization may take part in plaque destabilization and thromboembolic events. Anti-angiogenic agents are effective to reduce atherosclerosis progression in various animal models. However, clinical trials with anti-angiogenic drugs, mainly anti-VEGF/VEGFR, used in anti-cancer therapy show cardiovascular adverse effects, and require additional investigations.

Membrane-anchored proteases in endothelial cell biology

PURPOSE OF REVIEW

The endothelial cell plasma membrane is a metabolically active, dynamic, and fluid microenvironment where pericellular proteolysis plays a critical role. Membrane-anchored proteases may be expressed by endothelial cells as well as mural cells and leukocytes with distribution both inside and outside of the vascular system. Here, we will review the recent advances in our understanding of the direct and indirect roles of membrane-anchored proteases in vascular biology and the possible conservation of their extravascular functions in endothelial cell biology.

RECENT FINDINGS

Membrane-anchored proteases belonging to the serine or metalloprotease families contain amino-terminal or carboxy-terminal domains, which serve to tether their extracellular protease domains directly at the plasma membrane. This architecture enables protease function and substrate repertoire to be regulated through dynamic localization in distinct areas of the cell membrane. These proteases are proving to be key components of the cell machinery for regulating vascular permeability, generation of vasoactive peptides, receptor tyrosine kinase transactivation, extracellular matrix proteolysis, and angiogenesis.

SUMMARY

A complex picture of the interdependence between membrane-anchored protease localization and function is emerging that may provide a mechanism for precise coordination of extracellular signals and intracellular responses through communication with the cytoskeleton and with cellular signaling molecules.

Expression of matrix metalloproteinase−2 and −9 in human ligamentum flavum cells treated with tumor necrosis factor−α and interleukin-1β

OBJECT

An in vitro study was performed to understand the potential roles of matrix metalloproteinase (MMP)-2 and MMP-9 in the elastin degradation of human ligamentum flavum (LF) cells via treatment with tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β). Previous studies have identified a decreased elastin to collagen ratio in hypertrophic LF. Among the extracellular matrix remodeling endopeptidases, MMP-2 and MMP-9 are known to have elastolytic activity. The hypothesis that activated LF cells exposed to inflammation would secrete MMP-2 and MMP-9, thereby resulting in elastin degradation, was examined.

METHODS

To examine MMP-2 and MMP-9 expression in human LF, cells were isolated and cultured from LF tissues that were obtained during lumbar disc surgery. Isolated LF cells were equally divided into 3 flasks and subcultured. Upon cellular confluency, the LF cells were treated with TNFα, IL-1β, or none (as a control) and incubated for 48 hours. The conditioned media were collected and assayed for MMP-2 and MMP-9 using gelatin zymography and Western blot analysis. The electrophoresis bands were compared on densitometric scans using ImageJ software.

RESULTS

The conditioned media from the isolated human LF cells naturally expressed 72-kD and 92-kD gelatinolytic activities on gelatin zymography. The IL-1β-treated LF cells presented sustained increases in the proenzyme/zymogen forms of MMP−2 and −9 (proMMP-2 and proMMP-9), and activeMMP-9 expression (p = 0.001, 0.022, and 0.036, respectively); the TNFα-treated LF cells showed the most elevated proMMP9 secretion (p = 0.006), as determined by Western blot analyses. ActiveMMP-2 expression was not observed on zymography or the Western blot analysis.

CONCLUSIONS

TNFα and IL-1β promote proMMP-2 and proMMP-9 secretion. IL-1β appears to activate proMMP-9 in human LF cells. Based on these findings, selective MMP-9 blockers or antiinflammatory drugs could be potential treatment options for LF hypertrophy.

Genetic polymorphisms of matrix metalloproteinases and protein levels in chronic obstructive pulmonary disease in a Mexican population

AIM

To evaluate association of single nucleotide polymorphisms (SNPs) in the MMP1, MMP2, MMP9 and MMP12 genes and serum MMP-2 and MMP-9 levels in smoking chronic obstructive pulmonary disease (COPD) patients.

MATERIALS & METHODS

Genotyping using real-time PCR in 330 smokers with COPD (COPD), 658 smokers without COPD (SNC) and 150 nonsmokers (NCNS), the analysis of samples used was χ(2) test. Using ELISA, the proteins were evaluated. Multiple comparisons were made by ANOVA.

RESULTS

rs243864 (OR: 7.44; 95% CI: 3.62-15.26) and rs11646643 (OR: 1.58; 95% CI: 1.07-2.34) of the MMP-2 gene and rs3918253 (OR: 1.72; 95% CI: 1.08-2.71) of the MMP-9 gene, were associated with the risk of COPD. Serum MMP-2 level in the COPD group was lower compared with SNC (p < 0.05). Serum MMP-9 level was elevated in the COPD group compared with SNC (p < 0.05).

CONCLUSION

Polymorphisms in MMP2 and MMP9 but not in MMP1 and MMP12 are associated with the risk of COPD in the Mexican mestizo population.

Increased expression of angiogenic factors in cultured human brain arteriovenous malformation endothelial cells

To compare the mRNA level of angiogenic factor vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP)-2, and MMP-9 in cultured human brain arteriovenous malformation (AVM) endothelial cells (ECs) and normal brain endothelial cells (BECs). Tissue explants both from deformed vessels of AVM and normal microvessel were put into culture for endothelial cells. After the monolayer adherent ECs reached confluence, they were tested with endothelial specific marker CD34 and von Willebrand factor (vWF) by immunochemical assay. mRNA levels of VEGF-A, MMP-2, and MMP-9 in AVM endothelial cells (AVMECs) and BECs were measured by PCR. Immunostaining confirmed that more than 95 % of the cultured cells were CD34 (Fig. 1b) and/or vWF positive. Expression levels of VEGF-A and MMP-2 mRNAs were significantly higher in AVMECs than in BECs. The MMP-9 level was also increased in AVMECs, but the difference was not statistically significant. Vascular tissue explants adherent method is a better approach for isolation and culture of AVMECs. Cultured AVMECs expressed higher angiogenic factors (VEGF, MMP-2) than the controlled BECs, implicating angiogenesis plays an important role in the pathogenesis of AVM.

Different Preference of Degradome in Invasion versus Angiogenesis

Proteases are required for a multitude of cellular processes including homeostatic tissue remodelling, invasion and angiogenesis. The physiological function of a cell or tissue is reflected by the set of proteases expressed, also termed degradome. The role of proteases in invasion and angiogenesis has been studied intensively, mostly in cancer. We aimed to compare the set of proteases required for physiological invasion versus physiological angiogenesis from cells deriving from the same organ, and to identify the proteases specific for each process. The human placenta comprises trophoblasts that invade the maternal uterus in a regulated, physiological manner, and it is the source of primary endothelial cells. We isolated the trophoblasts and endothelial cells and verified their invasive phenotype and angiogenic properties, respectively. We then performed gene expression analysis of the degradome, e.g. cysteine, metallo, serine, threonine and aspartic proteases, identified the differentially expressed proteases among the trophoblasts and endothelial cells, and clustered them hierarchically. The results revealed that the set of proteases in trophoblasts versus in endothelial cells overlaps, with a total of 69% in common. Nevertheless, 42% of the studied degradomes differed, with a fold change ≥2. For instance, metalloproteinases were predominantly expressed in trophoblasts, and 31% of the proteases were exclusively expressed in either trophoblasts or endothelial cells; this suggests particular roles for these proteases in either invasion or angiogenesis. Our data identify common and distinct proteases in cells capable of performing invasion and angiogenesis, and may provide basic information for the design of techniques to specifically investigate invasion or angiogenesis.

Arachidonic acid promotes skin wound healing through induction of human MSC migration by MT3-MMP-mediated fibronectin degradation

Arachidonic acid (AA) is largely released during injury, but it has not been fully studied yet how AA modulates wound repair with stem cells. Therefore, we investigated skin wound-healing effect of AA-stimulated human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in vivo and its molecular mechanism in vitro. We found that transplantation of hUCB-MSCs pre-treated with AA enhanced wound filling, re-epithelization, and angiogenesis in a mouse skin excisional wound model. AA significantly promoted hUCB-MSCs migration after a 24 h incubation, which was inhibited by the knockdown of G-protein-coupled receptor 40 (GPR40). AA activated mammalian target of rapamycin complex 2 (mTORC2) and Akt^ser473 through the GPR40/phosphoinositide 3-kinase (PI3K) signaling, which was responsible for the stimulation of an atypical protein kinase C (PKC) isoform, PKCζ. Subsequently, AA stimulated phosphorylation of p38 MAPK and transcription factor Sp1, and induced membrane type 3-matrix metalloproteinase (MT3-MMP)-dependent fibronectin degradation in promoting hUCB-MSCs motility. Finally, the silencing of MT3-MMP in AA-stimulated hUCB-MSCs failed to promote the repair of skin wounds owing to impaired cell motility. In conclusion, AA enhances skin wound healing through induction of hUCB-MSCs motility by MT3-MMP-mediated fibronectin degradation, which relies on GPR40-dependent mTORC2 signaling pathways.

Soluble factors from the notochordal-rich intervertebral disc inhibit endothelial cell invasion and vessel formation in the presence and absence of pro-inflammatory cytokines

BACKGROUND

Chronic low back pain can be associated with the pathological ingrowth of blood vessels and nerves into intervertebral discs (IVDs). The notochord patterns the IVD during development and is a source of anti-angiogenic soluble factors such as Noggin and Chondroitin sulfate (CS). These factors may form the basis for a new minimally invasive strategy to target angiogenesis in the IVD.

OBJECTIVE

To examine the anti-angiogenic potential of soluble factors from notochordal cells (NCs) and candidates Noggin and CS under healthy culture conditions and in the presence of pro-inflammatory mediators.

DESIGN

NC conditioned media (NCCM) was generated from porcine NC-rich nucleus pulposus tissue. To assess the effects of NCCM, CS and Noggin on angiogenesis, cell invasion and tubular formation assays were performed using human umbilical vein endothelial cells (HUVECs) ± tumor necrosis factor alpha (TNFα [10 ng/ml]). vascular endothelial growth factor (VEGF)-A, MMP-7, interleukin-6 (IL-6) and IL-8 mRNA levels were assessed using qRT-PCR.

RESULTS

NCCM (10 & 100%), CS (10 and 100 μg) and Noggin (10 and 100 ng) significantly decreased cell invasion of HUVECs with and without TNFα. NCCM 10% and Noggin 10 ng inhibited tubular formation with and without TNFα and CS 100 μg inhibited tubules in Basal conditions whereas CS 10 μg inhibited tubules with TNFα. NCCM significantly decreased VEGF-A, MMP-7 and IL-6 mRNA levels in HUVECs with and without TNFα. CS and Noggin had no effects on gene expression.

CONCLUSIONS

We provide the first evidence that soluble factors from NCs can inhibit angiogenesis by suppressing VEGF signaling. Notochordal-derived ligands are a promising minimally invasive strategy targeting neurovascular ingrowth and pain in the degenerated IVD.

Patterning vascular networks in vivo for tissue engineering applications

The ultimate design of functionally therapeutic engineered tissues and organs will rely on our ability to engineer vasculature that can meet tissue-specific metabolic needs. We recently introduced an approach for patterning the formation of functional spatially organized vascular architectures within engineered tissues in vivo. Here, we now explore the design parameters of this approach and how they impact the vascularization of an engineered tissue construct after implantation. We used micropatterning techniques to organize endothelial cells (ECs) into geometrically defined "cords," which in turn acted as a template after implantation for the guided formation of patterned capillaries integrated with the host tissue. We demonstrated that the diameter of the cords before implantation impacts the location and density of the resultant capillary network. Inclusion of mural cells to the vascularization response appears primarily to impact the dynamics of vascularization. We established that clinically relevant endothelial sources such as induced pluripotent stem cell-derived ECs and human microvascular endothelial cells can drive vascularization within this system. Finally, we demonstrated the ability to control the juxtaposition of parenchyma with perfused vasculature by implanting cords containing a mixture of both a parenchymal cell type (hepatocytes) and ECs. These findings define important characteristics that will ultimately impact the design of vasculature structures that meet tissue-specific needs.

Pericellular proteolysis in cancer

Pericellular proteases have long been associated with cancer invasion and metastasis due to their ability to degrade extracellular matrix components. Recent studies demonstrate that proteases also modulate tumor progression and metastasis through highly regulated and complex processes involving cleavage, processing, or shedding of cell adhesion molecules, growth factors, cytokines, and kinases. In this review, we address how cancer cells, together with their surrounding microenvironment, regulate pericellular proteolysis. We dissect the multitude of mechanisms by which pericellular proteases contribute to cancer progression and discuss how this knowledge can be integrated into therapeutic opportunities.

Protease-sensitive PEG hydrogels regulate vascularization in vitro and in vivo

Forming functional blood vessel networks in engineered or ischemic tissues is a significant scientific and clinical hurdle. Poly(ethylene glycol) (PEG)-based hydrogels are adapted to investigate the role of mechanical properties and proteolytic susceptibility on vascularization. Four arm PEG vinyl sulfone is polymerized by Michael-type addition with cysteine groups on a slowly degraded matrix metalloprotease (MMP) susceptible peptide, GPQG↓IWGQ, or a more rapidly cleaved peptide, VPMS↓MRGG. Co-encapsulation of endothelial cells and supportive fibroblasts within the gels lead to vascular morphogenesis in vitro that is robust to changes in crosslinking peptide identity, but is significantly attenuated by increased crosslinking and MMP inhibition. Perfused vasculature forms from transplanted cells in vivo in all gel types; however, in contrast to the in vitro results, vascularization in vivo is not decreased in the more crosslinked gels. Collectively, these findings demonstrate the utility of this platform to support vascularization both in vitro and in vivo.

Beclin1 inhibits proliferation, migration and invasion in tongue squamous cell carcinoma cell lines

OBJECTIVES

The role of autophagy is still a controversy in cancer development. In our previous study, we confirmed that decrease of autophagy activity promotes malignant progression of tongue squamous cell carcinoma (TSCC). However, the role of autophagy-related protein, Beclin1, has not well been documented in TSCC. In this study, we aim to elucidate the role of beclin1 in TSCC progression and investigate its potential mechanisms.

MATERIALS AND METHODS

TSCC cell lines, SCC9 and SCC15 were used to generate the stable cells with transfection lentivirus BECN1 and sh-BECN1. Then, Beclin1 expression was detected with qPCR and western blot. Moreover, the expressions of autophagy-related proteins and tumor metastasis associated proteins were examined by western blot and ELISA. For functional analysis, MTT assay were performed to evaluate the proliferation activity and transwell assay was used to assess the migration and invasion ability. Finally, TSCC xenograft models were established to confirm the effect of Beclin1 on TSCC in vivo.

RESULTS

The results showed that BECN1 and sh-BECN1 virus transfection significantly increased or decreased the mRNA and protein expression of Beclin1 in the transfected TSCC cells. Meanwhile, we also observed that Beclin1 could enhance the expression levels of LC3-II, ATG4 and ATG5. Then, we revealed that overexpression of Beclin1 inhibited proliferation, migration and invasion while knockdown of Beclin1 promoted proliferation, migration and invasion in TSCC cells. Furthermore, we demonstrated that vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 and -9 were involved in Beclin1-mediated inhibition of migration and invasion. More importantly, our data also confirmed that Beclin1 inhibited TSCC xenograft growth in vivo.

CONCLUSION

Taken together, the results indicate that autophagy regulating gene, Beclin1, may contribute to the malignant phenotypes of TSCC cells and can be a potential target for oral cancer gene therapy.

Clinical significance of integrin β6 as a tumor recurrence factor in follicular thyroid carcinoma

BACKGROUND

Overexpression of integrin β6 plays an important role in a variety of malignant tumor invasion and metastasis.

METHODS

The expression levels of integrin β6, matrix metalloproteinase (MMP)-2 and MMP-9 were analyzed by immunohistochemistry with human follicular thyroid carcinomas. Then we investigated their correlation with clinical outcomes parameters, relationship, and the survival time.

RESULTS

The integrin β6 staining was expressed in cellular membrane and cytoplasm of follicular thyroid carcinoma cells. The MMP-2 and MMP-9 expressions were mainly found in cellular cytoplasm. In correlation with the clinical outcome parameters of 60 patients, there were significant statistical differences of integrin β6, MMP-2, and MMP-9 expression levels in different size of tumor. Integrin β6 and MMP-9 expressions have significant statistical differences in T classifications. MMP-2 and MMP-9 expressions have significant statistical differences in different M classification. Other clinical outcome parameters had no significant statistical differences.

CONCLUSION

Integrin β6 expression correlated significantly with MMP-9 expression, and may be a valuable recurrence indicator for follicular thyroid carcinomas.

Estrogen up-regulates MMP2/9 expression in endometrial epithelial cell via VEGF-ERK1/2 pathway

OBJECTIVE

To study the effect of estrogen on anovulatory dysfunctional uterine bleeding (ADUB).

METHODS

Primary endometrial epithelial cells of Hainan Lizu female was cultured and hydrolytic activity of gelatinase was determined by gelatin zymography analysis. Cellular mRNA and protein synthesis was blocked respectively to determine whether the increased expression of MMP-2/9 was induced by estrogen. The expression of VEGF was blocked by siRNA. After treatment with various factors, MMP-9, VEGF, total Erk and phosphorylated Erk expression in primary uterine epithelial cells was detected by Western blotting analysis. Cell MMP-2/9mRNA levels was measured by real-time RT-PCR.

RESULTS

The activity and expression of MMP2/9 was increased in the endometrium of patients with ADUB. Estrogen could up-regulate the expression of VEGF and activate Erk 1/2-Elk1 signal path. After interference by siRNA, ERK1/2 pathway was blocked in cells, and the expression of MMP-2/9 was down-regulated. ERK1/2 specific blocker U0126 blocked ERK phosphorylation, and it could down-regulate the expression of MMP-2/9.

CONCLUSIONS

The results showed that the estrogen can increase the expression of VEGF, and thus activate ERK1/2 pathway to induce MMP-2/9 expression.

Using Del-1 to tip the angiogenic balance in endothelial cells in modular constructs

Modular tissue engineering is a method of building vascularized tissue-engineered constructs. Submillimeter-sized collagen pieces (modules) coated with a layer of endothelial cells (EC; vascular component), and with embedded functional cells, are self-assembled into a larger, three-dimensional tissue. In this study, we examined the use of developmental endothelial locus-1 (Del-1), an extracellular matrix protein with proangiogenic properties, as a means of tipping the angiogenic balance in human umbilical vein endothelial cells incorporated in modular tissue-engineered constructs. The motivation was to enhance the vascularization of these constructs upon transplantation in vivo, in this case, without the use of exogenous mesenchymal stromal cells. EC were transduced using a lentiviral construct to overexpress Del-1. The Del-1 EC formed more sprouts in a fibrin gel sprouting assay in vitro compared with eGFP (control) transduced EC, as expected. Del-1 EC had a distinct profile of gene expression (upregulation of matrix metalloproteinase-9 [MMP-9], urokinase-type plasminogen activator [uPA/PLAU], vascular endothelial growth factor [VEGF-A], and intercellular adhesion molecule-1 [ICAM-1]; downregulation of angiopoietin-2 [Ang2]), also supporting the notion of "tipping the angiogenic balance". On the other hand, contrary to our expectations, when Del-1 EC-coated modules were implanted subcutaneously in a severe combined immunodeficient/beige animal model, the proangiogenic effect of Del-1 was less remarkable. There was only a small increase in the number of blood vessels formed in Del-1 implants compared with the eGFP implants, and only few blood vessels formed at the implant site in both cases. This was presumed due to limited EC survival after transplantation. We speculate that if we could improve EC survival in our study (for example, by adding other prosurvival factors or supporting cells), we would see a greater Del-1-induced angiogenic benefit in vivo as a consequence of increased Del-1 secretion by a higher number of surviving cells.

Effects of secreted factors in culture medium of annulus fibrosus cells on microvascular endothelial cells: elucidating the possible pathomechanisms of matrix degradation and nerve in-growth in disc degeneration

OBJECTIVE

To test whether the interaction between annulus fibrosus cells (AFCs) and endothelial cells (ECs) disrupts matrix homeostasis and stimulates production of innervation mediators.

METHODS

Human microvascular ECs were cultured in the conditioned media of AF cell culture derived from degenerated human surgical specimen. Matrix-metalloproteinases (MMPs) and platelet-derived growth factor (PDGF) of ECs of this culture were analyzed by qRT-PCR, Western, and immunofluorescence. Vascular endothelial growth factor (VEGF), Interleukin-8 (IL-8), and nerve growth factor (NGF) in the media of this cell culture were assayed by ELISA. To determine the effects of ECs on AFCs, qRT-PCR was performed to determine mRNA levels of collagen I, II and aggrecan in AFCs cultured in EC conditioned media.

RESULTS

Compared to ECs cultured in naïve media, ECs exposed to AFC conditioned media expressed higher mRNA and protein levels of key biomarkers of invasive EC phenotype, MMP-2 (2×), MMP-13 (4×), and PDGF-B (1.5-2×), and NGF (24.9 ± 15.2 pg/mL vs 0 in naïve media). Treatment of AF cells with EC culture conditioned media decreased collagen type II expression two fold. Considerable quantities of pro-angiogenic factors IL-8 (396.7 ± 302.0 pg/mL) and VEGF (756.2 ± 375.9 pg/mL) were also detected in the conditioned media of untreated AF cell culture.

DISCUSSION

AFCs from degenerated discs secreted factors which stimulated EC production of factors known to induce matrix degradation, angiogenesis, and innervation. IL-8 and VEGF maybe the secreted factors from AFCs which mediate a pro-angiogenic stimulus often implicated in the development of disc degeneration.

Sintered anorganic bone graft increases autocrine expression of VEGF, MMP-2 and MMP-9 during repair of critical-size bone defects

This study aimed to evaluate morphometrically the bone formation and immunohistochemically the expression of vascular endothelial growth factor (VEGF) and metalloproteinase (MMP)-2 and -9 during the healing of critical-size defects treated with sintered anorganic bone (sAB). The 8-mm diameter full-thickness trephine defects created in the parietal bones of rats were filled with sAB (test group) or blood clot (CSD-control group). At 7, 14, 21, 30, 90 and 180 days postoperatively (n = 6/period) the volume of newly formed bone and total number of immunolabeled cells (Ntm) for each protein were determined. Bone formation was smaller and faster in the CSD-control group, stabilizing at 21 days (6.74 mm(3)). The peaks of VEGF, MMP-2 and MMP-9 occurred at 7 and 14 days in fibroblasts and osteoblasts, with mean reduction of 0.80 time at 21 days, keeping constant until 180 days. In the test group, sAB provided continuous bone formation between particles throughout all periods. The peak of MMP-2 was observed at 7-14 days in connective tissue cells and for VEGF and MMP-9 at 30 days in osteoblasts and osteocytes. Ntm for VEGF, MMP-2 and MMP-9 were in average, respectively, 3.70, 2.03 and 5.98 times higher than in the control group. At 180 days, newly formed bone (22.9 mm(3)) was 3.74 times greater in relation to control. The physical and chemical properties of sAB allow increased autocrine expression of VEGF, MMP-2 and MMP-9, favoring bone formation/remodeling with very good healing of cranial defects when compared to natural repair in the CSD-control.

Chemical sintering generates uniform porous hyaluronic acid hydrogels

The implantation of scaffolds for tissue repair has achieved only limited success due primarily to the inability to achieve vascularization within the construct. Many strategies have therefore moved to incorporate pores into the scaffolds to encourage rapid cellular infiltration and subsequent vascular ingrowth. We utilized an efficient chemical sintering technique to create a uniform network of polymethyl methacrylate (PMMA) microspheres for porous hyaluronic acid hydrogel formation. The porous hydrogels generated from chemical sintering possessed pore uniformity and interconnectivity comparable to the commonly used non- and heat sintering techniques. Moreover, a similar cell response to the porous hydrogels generated from each sintering approach was observed in cell viability, spreading and proliferation in vitro, as well as cellular invasion in vivo. We propose chemical sintering of PMMA microspheres using a dilute acetone solution as an alternative method to generate porous hyaluronic acid hydrogels since it requires equal or 10-fold less processing time as the currently used non-sintering or heat sintering technique, respectively.