Microenvironment drives the endothelial or neural fate of differentiating embryonic stem cells coexpressing neuropilin-1 and Flk-1

GRIN2A mutation is a novel indicator of stratifying beneficiaries of immune checkpoint inhibitors in multiple cancers

Glutamate-NMDAR receptors (GRINs) have been reported to influence cancer immunogenicity; however, the relationship between GRIN alterations and the response to immune checkpoint inhibitors (ICIs) has not been determined. This study combined clinical characteristics and mutational profiles from multiple cohorts to form a discovery cohort (n = 901). The aim of this study was to investigate the correlation between the mutation status of the GRIN gene and the response to ICI therapy. Additionally, an independent ICI-treated cohort from the Memorial Sloan Kettering Cancer Center (MSKCC, N = 1513) was used for validation. Furthermore, this study explored the associations between GRIN2A mutations and intrinsic and extrinsic immunity using multiomics analysis. In the discovery cohort, patients with GRIN2A-MUTs had improved clinical outcomes, as indicated by a higher objective response rate (ORR: 36.8% vs 25.8%, P = 0.020), durable clinical benefit (DCB: 55.2% vs 38.7%, P = 0.005), prolonged progression-free survival (PFS: HR = 0.65; 95% CI 0.49 to 0.87; P = 0.003), and increased overall survival (OS: HR = 0.67; 95% CI 0.50 to 0.89; P = 0.006). Similar results were observed in the validation cohort, in which GRIN2A-MUT patients exhibited a significant improvement in overall survival (HR = 0.66; 95% CI = 0.49 to 0.88; P = 0.005; adjusted P = 0.045). Moreover, patients with GRIN2A-MUTs exhibited an increase in tumor mutational burden, high expression of costimulatory molecules, increased activity of antigen-processing machinery, and infiltration of various immune cells. Additionally, gene sets associated with cell cycle regulation and the interferon response were enriched in GRIN2A-mutated tumors. In conclusion, GRIN2A mutation is a novel biomarker associated with a favorable response to ICIs in multiple cancers.

The Nervous System Development Regulator Neuropilin-1 as a Potential Prognostic Marker and Therapeutic Target in Brain Cancer

Neuropilins are transmembrane glycoproteins that regulate developmental processes in the nervous system and other tissues. Overexpression of neuropilin-1 (NRP1) occurs in many solid tumor types and, in several instances, may predict patient outcome in terms of overall survival. Experimental inhibition of NRP1 activity can display antitumor effects in different cancer models. Here, we review NRP1 expression and function in adult and pediatric brain cancers, particularly glioblastomas (GBMs) and medulloblastomas, and present analyses of NRP1 transcript levels and their association with patient survival in GBMs. The case of NRP1 highlights the potential of regulators of neurodevelopment as biomarkers and therapeutic targets in brain cancer.

Targeting neuropilin-1 interactions is a promising anti-tumor strategy

ABSTRACT

Neuropilins (NRP1 and NRP2) are multifunctional receptor proteins that are involved in nerve, blood vessel, and tumor development. NRP1 was first found to be expressed in neurons, but subsequent studies have demonstrated its surface expression in cells from the endothelium and lymph nodes. NRP1 has been demonstrated to be involved in the occurrence and development of a variety of cancers. NRP1 interacts with various cytokines, such as vascular endothelial growth factor family and its receptor and transforming growth factor β1 and its receptor, to affect tumor angiogenesis, tumor proliferation, and migration. In addition, NRP1+ regulatory T cells (Tregs) play an inhibitory role in tumor immunity. High numbers of NRP1+ Tregs were associated with cancer prognosis. Targeting NRP1 has shown promise, and antagonists against NRP1 have had therapeutic efficacy in preliminary clinical studies. NRP1 treatment modalities using nanomaterials, targeted drugs, oncolytic viruses, and radio-chemotherapy have gradually been developed. Hence, we reviewed the use of NRP1 in the context of tumorigenesis, progression, and treatment.

Glutamate dependent NMDA receptor 2D is a novel angiogenic tumour endothelial marker in colorectal cancer

Current vascular-targeted therapies in colorectal cancer (CRC) have shown limited benefit. The lack of novel, specific treatment in CRC has been hampered by a dearth of specific endothelial markers. Microarray comparison of endothelial gene expression in patient-matched CRC and normal colon identified a panel of putative colorectal tumour endothelial markers. Of these the glutamate dependent NMDA receptor GRIN2D emerged as the most interesting target. GRIN2D expression was shown to be specific to colorectal cancer vessels by RTqPCR and IHC analysis. Its expression was additionally shown be predictive of improved survival in CRC. Targeted knockdown studies in vitro demonstrated a role for GRIN2D in endothelial function and angiogenesis. This effect was also shown in vivo as vaccination against the extracellular region of GRIN2D resulted in reduced vascularisation in the subcutaneous sponge angiogenesis assay. The utility of immunologically targeting GRIN2D in CRC was demonstrated by the vaccination approach inhibiting murine CRC tumour growth and vascularisation. GRIN2D represents a promising target for the future treatment of CRC.

Function of members of the neuropilin family as essential pleiotropic cell surface receptors

The neuropilin (Nrp) family consists of essential multifunctional vertebrate cell surface receptors. Nrps were initially characterized as receptors for class III Semaphorin (Sema3) family members, functioning in axon guidance. Nrps have also been shown to be critical for vascular endothelial growth factor-dependent angiogenesis. Intriguingly, recent data show that Nrp function in these seemingly divergent pathways is critically determined by ligand-mediated cross-talk, which underlies Nrp function in both physiological and pathological processes. In addition to functioning in these two pathways, Nrps have been shown to specifically function in a number of other fundamental signaling pathways as well. Multiple general mechanisms have been found to directly contribute to the pleiotropic function of Nrp. Here we review critical general features of Nrps that function as essential receptors integrating multiple molecular cues into diverse cellular signaling.

Neuropilins are multifunctional coreceptors involved in tumor initiation, growth, metastasis and immunity

The neuropilins (Nrps) are multifunctional proteins involved in development, immunity and cancer. Neuropilin-1 (Nrp1), or its homologue neuropilin-2 (Nrp2), are coreceptors that enhance responses to several growth factors (GFs) and other mediators. Nrps are coreceptors for the class 3 semaphorins (SEMA3), involved in axonal guidance, and several members of the vascular endothelial growth factor (VEGF) family. However, recent findings reveal they have a much broader spectrum of activity. They bind transforming growth factor β1 (TGF-β1) and its receptors, hepatocyte growth factor (HGF) and its receptor (cMet), platelet derived growth factor (PDGF) and its receptors, fibroblast growth factors (FGFs), and integrins. Nrps also promote Hedgehog signaling. These ligands and pathways are all relevant to angiogenesis and wound healing. In the immune system, the Nrps are expressed primarily by dendritic cells (DCs) and regulatory T cells (Tregs), and exert mainly inhibitory effects. In cancer, Nrps have been linked to a poor prognosis, which is consistent with their numerous interactions with ligands and receptors that promote tumor progression. We hypothesize that Nrps boost responses by capturing ligands, regulating GF receptor expression, endocytosis and recycling, and possibly also by signaling independently. Importantly, they promote epithelial-mesenchymal transition (EMT), and the survival of cancer stem cells. The recent finding that Nrps bind and internalize cell-penetrating peptides (CPPs) with arginine/lysine-rich C-terminal motifs (C-end rule; e.g., RXXR) is of interest. These CPPs can be coupled to large drugs for cancer therapy. Almost all studies have been preclinical, but findings suggest Nrps are excellent targets for anti-cancer drug development.

Mature endothelium and neurons are simultaneously derived from embryonic stem cells by 2D in vitro culture system

The connections existing between vessels and nerves go beyond the structural architecture of vascular and nervous systems to comprise cell fate determination. The analysis of functional/molecular links that interconnect endothelial and neural commitments requires a model in which the two differentiation programs take place at the same time in an artificial controllable environment. To this regard, this work presents an in vitro model to differentiate embryonic stem (ES) cells simultaneously into mature neurons and endothelial cells. Murine ES cells are differentiated within an artificial environment composed of PA6 stromal cells and a serum-free medium. Upon these basal culture conditions ES cells preferentially differentiate into neurons. The addition of basic fibroblast growth factor (FGF2) to the medium allows the simultaneous maturation of neurons and endothelial cells, whereas bone morphogenetic protein (BMP)4 drives endothelial differentiation to the disadvantage of neural commitment. The responsiveness of the system to exogenous cytokines was confirmed by genes expression analysis that revealed a significant up-regulation of endothelial genes in presence of FGF2 and a massive down-regulation of the neural markers in response to BMP4. Furthermore, the role played by single genes in determining endothelial and neural fate can be easily explored by knocking down the expression of the target gene with lentiviruses carrying the corresponding shRNA sequence. The possibility to address the neural and the endothelial fate separately or simultaneously by exogenous stimuli combined with an efficient gene silencing strategy make this model an optimal tool to identify environmental signals and genes pathways involved in both endothelial and neural specification.

VEGFR-1 mediates endothelial differentiation and formation of blood vessels in a murine model of infantile hemangioma

Vascular endothelial growth factor receptor-1 (VEGFR-1) is a member of the VEGFR family, and binds to VEGF-A, VEGF-B, and placental growth factor. VEGFR-1 contributes to tumor growth and metastasis, but its role in the pathological formation of blood vessels is still poorly understood. Herein, we used infantile hemangioma (IH), the most common tumor of infancy, as a means to study VEGFR-1 activation in pathological vasculogenesis. IH arises from stem cells (HemSCs) that can form the three most prominent cell types in the tumor: endothelial cells, pericytes, and adipocytes. HemSCs can recapitulate the IH life cycle when injected in immuncompromised mice, and are targeted by corticosteroids, the traditional treatment for IH. We report here that VEGF-A or VEGF-B induces VEGFR-1-mediated ERK1/2 phosphorylation in HemSCs and promotes differentiation of HemSCs to endothelial cells. Studies of VEGFR-2 phosphorylation status and down-regulation of neuropilin-1 in the HemSCs demonstrate that VEGFR-2 and NRP1 are not needed for VEGF-A- or VEGF-B-induced ERK1/2 activation. U0216-mediated blockade of ERK1/2 phosphorylation or shRNA-mediated suppression of VEGFR-1 prevents HemSC-to-EC differentiation. Furthermore, the down-regulation of VEGFR-1 in the HemSCs results in decreased formation of blood vessels in vivo and reduced ERK1/2 activation. Thus, our study reveals a critical role for VEGFR-1 in the HemSC-to-EC differentiation that underpins pathological vasculogenesis in IH.

Ex vivo-expanded bone marrow CD34(+) for acute myocardial infarction treatment: in vitro and in vivo studies

BACKGROUND AIMS

Bone marrow (BM)-derived cells appear to be a promising therapeutic source for the treatment of acute myocardial infarction (AMI). However, the quantity and quality of the cells to be used, along with the appropriate time of administration, still need to be defined. We thus investigated the use of BM CD34(+)-derived cells as cells suitable for a cell therapy protocol (CTP) in the treatment of experimental AMI.

METHODS

The need for a large number of cells was satisfied by the use of a previously established protocol allowing the expansion of human CD34(+) cells isolated from neonatal and adult hematopoietic tissues. We evaluated gene expression, endothelial differentiation potential and cytokine release by BM-derived cells during in vitro culture. Basal and expanded CD34(+) cells were used as a delivery product in a murine AMI model consisting of a coronary artery ligation (CAL). Cardiac function recovery was evaluated after injecting basal or expanded cells.

RESULTS

Gene expression analysis of in vitro-expanded cells revealed that endothelial markers were up-regulated during culture. Moreover, expanded cells generated a CD14(+) subpopulation able to differentiate efficiently into VE-cadherin-expressing cells. In vivo, we observed a cardiac function recovery in mice sequentially treated with basal and expanded cells injected 4 h and 7 days after CAL, respectively.

CONCLUSIONS

Our data suggest that combining basal and expanded BM-derived CD34(+) cells in a specific temporal pattern of administration might represent a promising strategy for a successful cell-based therapy.

Transplantation of mammalian embryonic stem cells and their derivatives to avian embryos

Xenografting of normal and transformed mammalian tissues and cells to chick embryos has been performed for almost 100 years. Embryonic stem cells, derived more than 25 years ago from murine, and more than 10 years ago from human blastocysts, have transformed many fields of biological research. There is a growing body of studies combining these two widely-used experimental systems. This review surveys those reports in which murine or human embryonic stem cells, or differentiated derivatives of these pluripotent stem cells, were transplanted to embryonated chick eggs. Many of these studies have utilized the unique characteristics of both experimental models to obtain answers to developmental questions that are difficult or impossible to approach with xenografting to adult rodents or tissue culture-only techniques.

Exogenous recombinant dimeric neuropilin-1 is sufficient to drive angiogenesis

Neuropilin-1 (NRP-1) is present on the cell surface of endothelial cells, or as a soluble truncated variant. Membrane NRP-1 is proposed to enhance angiogenesis by promoting the formation of a signaling complex between vascular endothelial growth factor-A(165) (VEGF-A(165)), VEGF receptor-2 (VEGFR-2) and heparan sulfate, whereas the soluble NRP-1 is thought to act as an antagonist of signaling complex formation. We have analyzed the angiogenic potential of a chimera comprising the entire extracellular NRP-1 region dimerized through an Fc IgG domain and a monomeric truncated NRP-1 variant. Both NRP-1 proteins stimulated tubular morphogenesis and cell migration in HDMECs and HUVECs. Fc rNRP-1 was able to induce VEGFR-2 phosphorylation and expression of the VEGFR-2 specific target, regulator of calcineurin-1 (RCAN1.4). siRNA mediated gene silencing of VEGFR-2 revealed that VEGFR-2 was required for Fc rNRP-1 mediated activation of the intracellular signaling proteins PLC-γ, AKT, and MAPK and tubular morphogenesis. The stimulatory activity was independent of VEGF-A(165). This was evidenced by depleting the cell culture of exogenous VEGF-A(165), and using instead for routine culture VEGF-A(121), which does not interact with NRP-1, and by the inability of VEGF-A sequestering antibodies to inhibit the angiogenic activity of the NRP proteins. Analysis of angiogenesis over a period of 6 days in an in vitro fibroblast/endothelial co-culture model revealed that Fc rNRP-1 could induce endothelial cell tubular morphogenesis. Thus, we conclude that soluble Fc rNRP-1 is a VEGF-A(165)-independent agonist of VEGFR-2 and stimulates angiogenesis in endothelial cells.

Role of the microenvironment in the specification of endothelial progenitors derived from embryonic stem cells

Embryonic stem (ES) cells are pluripotent cells capable of differentiating in all the cell types present in a living organism. They derive from the inner cell mass of blastocysts of different species including humans. Given their unlimited potential, ES cells represent an invaluable resource of different cell types for transplantation and tissue engineering applications. However, in order to accomplish these therapeutic purposes, efficient and controlled in vitro systems of directing ES cell differentiation are mandatory. ES cell differentiation is strongly influenced by physical, chemical and cellular signals provided by the local microenvironment. Understanding the relationships occurring between differentiating cells and surrounding environment is pivotal for a successful ES cells-based therapy. This review describes three different methods of in vitro differentiation of ES cells by outlining the environmental elements required for endothelial fate specification. For each system, the efficiency of endothelial differentiation, the accessibility and the advantages are discussed. The main conclusion that arises from this analysis is that the knowledge of the role played by microenvironment in cell fate determination is essential to control and take advantage of ES cells potential.

Embryoid body formation of human amniotic fluid stem cells depends on mTOR

Human amniotic fluid stem cells (hAFSCs) harbor high proliferative capacity and high differentiation potential and do not raise the ethical concerns associated with human embryonic stem cells. The formation of three-dimensional aggregates known as embryoid bodies (EBs) is the principal step in the differentiation of pluripotent embryonic stem cells. Using c-Kit-positive hAFSC lines, we show here that these stem cells harbor the potential to form EBs. As part of the two kinase complexes, mTORC1 and mTORC2, mammalian target of rapamycin (mTOR) is the key component of an important signaling pathway, which is involved in the regulation of cell proliferation, growth, tumor development and differentiation. Blocking intracellular mTOR activity through the inhibitor rapamycin or through specific small interfering RNA approaches revealed hAFSC EB formation to depend on mTORC1 and mTORC2. These findings demonstrate hAFSCs to be a new and powerful biological system to recapitulate the three-dimensional and tissue level contexts of in vivo development and identify the mTOR pathway to be essential for this process.

The neurovascular link in health and disease: an update

Although the nervous and vascular systems are functionally different, they show a high degree of anatomic parallelism and cross-talk. They also share similar mechanisms and molecular cues that regulate their development and maintenance. Malfunctioning of this cross-talk can cause or influence several vascular and neuronal disorders. In this review, we first provide a brief overview of the molecular and cellular mechanisms that govern the neurovascular link. Second, we focus on two neurodegenerative diseases, Alzheimer's disease and amyotrophic lateral sclerosis, to illustrate how a defective neurovascular link might contribute to their pathogenesis. Finally, we briefly discuss some therapeutic implications of the neurovascular link for designing strategies to treat these diseases.

The chick embryo: hatching a model for contemporary biomedical research

Animal models play a crucial role in fundamental and medical research. Progress in the fields of drug discovery, regenerative medicine and cancer research among others are heavily dependent on in vivo models to validate in vitro observations, and develop new therapeutic approaches. However, conventional rodent and large animal experiments face ethical, practical and technical issues that limit their usage. The chick embryo represents an accessible and economical in vivo model, which has long been used in developmental biology, gene expression analysis and loss/gain of function experiments. It is also an established model for tissue/cell transplantation, and because of its lack of immune system in early development, the chick embryo is increasingly recognised as a model of choice for mammalian biology with new applications for stem cell and cancer research. Here, we review novel applications of the chick embryo model, and discuss future developments of this in vivo model for biomedical research.