Co-culture of Retinal and Endothelial Cells Results in the Modulation of Genes Critical to Retinal Neovascularization

Pigment Epithelial-Derived Factor in Pancreatic and Liver Cancers-From Inflammation to Cancer

Gastrointestinal (GI) cancers are among the leading causes of mortality worldwide. Despite the emergence of new possibilities that offer hope regarding the successful treatment of these cancers, they still represent a significant global health burden. These cancers can arise from various cell types within the gastrointestinal tract and may exhibit different characteristics, behaviors, and treatment approaches. Both the prognosis and the outcomes of GI treatment remain problematic because these tumors are primarily diagnosed in advanced clinical stages. Current biomarkers exhibit limited sensitivity and specificity. Therefore, when developing strategies for the diagnosis and treatment of GI cancers, it is of fundamental importance to discover new biomarkers capable of addressing the challenges of early-stage diagnosis and the presence of lymph node metastases. Pigment epithelial-derived factor (PEDF) has garnered interest due to its inhibitory effects on the migration and proliferation of cancer cells. This protein has been suggested to be involved in various inflammation-related diseases, including cancer, through various mechanisms. It was also observed that reducing the level of PEDF is sufficient to trigger an inflammatory response. This suggests that PEDF is an endogenous anti-inflammatory factor. Overall, PEDF is a versatile protein with diverse biological functions that span across different tissues and organ systems. Its multifaceted activities make it an intriguing target for therapeutic interventions in various diseases, including cancer, neurodegeneration, and metabolic disorders. This review, for the first time, summarizes the role of PEDF in the pathogenesis of selected GI cancers and its potential utility in early diagnosis, prognosis, and therapeutic strategies for this malignancy.

In Vitro Studies to Evaluate the Intestinal Permeation of an Ursodeoxycholic Acid-Conjugated Oligonucleotide for Duchenne Muscular Dystrophy Treatment

Delivery represents a major hurdle to the clinical advancement of oligonucleotide therapeutics for the treatment of disorders such as Duchenne muscular dystrophy (DMD). In this preliminary study, we explored the ability of 2'-O-methyl-phosphorothioate antisense oligonucleotides (ASOs) conjugated with lipophilic ursodeoxycholic acid (UDCA) to permeate across intestinal barriers in vitro by a co-culture system of non-contacting IEC-6 cells and DMD myotubes, either alone or encapsulated in exosomes. UDCA was used to enhance the lipophilicity and membrane permeability of ASOs, potentially improving oral bioavailability. Exosomes were employed due to their biocompatibility and ability to deliver therapeutic cargo across biological barriers. Exon skipping was evaluated in the DMD myotubes to reveal the targeting efficiency. Exosomes extracted from milk and wild-type myotubes loaded with 5'-UDC-3'Cy3-ASO and seeded directly on DMD myotubes appear able to fuse to myotubes and induce exon skipping, up to ~20%. Permeation studies using the co-culture system were performed with 5'-UDC-3'Cy3-ASO 51 alone or loaded in milk-derived exosomes. In this setting, only gymnotic delivery induced significant levels of exon skipping (almost 30%) implying a possible role of the intestinal cells in enhancing delivery of ASOs. These results warrant further investigations to elucidate the delivery of ASOs by gymnosis or exosomes.

Advances in the engineering of the outer blood-retina barrier: From in-vitro modelling to cellular therapy

The outer blood-retina barrier (oBRB), crucial for the survival and the proper functioning of the overlying retinal layers, is disrupted in numerous diseases affecting the retina, leading to the loss of the photoreceptors and ultimately of vision. To study the oBRB and/or its degeneration, many in vitro oBRB models have been developed, notably to investigate potential therapeutic strategies against retinal diseases. Indeed, to this day, most of these pathologies are untreatable, especially once the first signs of degeneration are observed. To cure those patients, a current strategy is to cultivate in vitro a mature oBRB epithelium on a custom membrane that is further implanted to replace the damaged native tissue. After a description of the oBRB and the related diseases, this review presents an overview of the oBRB models, from the simplest to the most complex. Then, we propose a discussion over the used cell types, for their relevance to study or treat the oBRB. Models designed for in vitro applications are then examined, by paying particular attention to the design evolution in the last years, the development of pathological models and the benefits of co-culture models, including both the retinal pigment epithelium and the choroid. Lastly, this review focuses on the models developed for in vivo implantation, with special emphasis on the choice of the material, its processing and its characterization, before discussing the reported pre-clinical and clinical trials.

The Lymphatic Endothelial Cell Secretome Inhibits Osteoblast Differentiation and Bone Formation

Complex lymphatic anomalies (CLAs) are a set of rare diseases with unique osteopathic profiles. Recent efforts have identified how lymphatic-specific somatic activating mutations can induce abnormal lymphatic formations that are capable of invading bone and inducing bone resorption. The abnormal bone resorption in CLA patients has been linked to overactive osteoclasts in areas with lymphatic invasions. Despite these findings, the mechanism associated with progressive bone loss in CLAs remains to be elucidated. In order to determine the role of osteoblasts in CLAs, we sought to assess osteoblast differentiation and bone formation when exposed to the lymphatic endothelial cell secretome. When treated with lymphatic endothelial cell conditioned medium (L-CM), osteoblasts exhibited a significant decrease in proliferation, differentiation, and function. Additionally, L-CM treatment also inhibited bone formation through a neonatal calvaria explant culture. These findings are the first to reveal how osteoblasts may be actively suppressed during bone lymphatic invasion in CLAs.

Stem cells and diabetic retinopathy: From models to treatment

Diabetic retinopathy is a common yet complex microvascular disease, caused as a complication of diabetes mellitus. Associated with hyperglycemia and subsequent metabolic abnormalities, advanced stages of the disease lead to fibrosis, subsequent visual impairment and blindness. Though clinical postmortems, animal and cell models provide information about the progression and prognosis of diabetic retinopathy, its underlying pathophysiology still needs a better understanding. In addition to it, the loss of pericytes, immature retinal angiogenesis and neuronal apoptosis portray the disease treatment to be challenging. Indulged with cell loss of both vascular and neuronal type cells, novel therapies like cell replacement strategies by various types of stem cells have been sightseen as a possible treatment of the disease. This review provides insight into the pathophysiology of diabetic retinopathy, current models used in modelling the disease, as well as the varied aspects of stem cells in generating three-dimensional retinal models. Further outlook on stem cell therapy and the future directions of stem cell treatment in diabetic retinopathy have also been contemplated.

3D iPSC modeling of the retinal pigment epithelium-choriocapillaris complex identifies factors involved in the pathology of macular degeneration

The retinal pigment epithelium (RPE)-choriocapillaris (CC) complex in the eye is compromised in age-related macular degeneration (AMD) and related macular dystrophies (MDs), yet in vitro models of RPE-CC complex that enable investigation of AMD/MD pathophysiology are lacking. By incorporating iPSC-derived cells into a hydrogel-based extracellular matrix, we developed a 3D RPE-CC model that recapitulates key features of both healthy and AMD/MD eyes and provides modular control over RPE and CC layers. Using this 3D RPE-CC model, we demonstrated that both RPE- and mesenchyme-secreted factors are necessary for the formation of fenestrated CC-like vasculature. Our data show that choroidal neovascularization (CNV) and CC atrophy occur in the absence of endothelial cell dysfunction and are not necessarily secondary to drusen deposits underneath RPE cells, and CC atrophy and/or CNV can be initiated systemically by patient serum or locally by mutant RPE-secreted factors. Finally, we identify FGF2 and matrix metalloproteinases as potential therapeutic targets for AMD/MDs.

Integrated contact lens sensor system based on multifunctional ultrathin MoS2 transistors

Smart contact lenses attract extensive interests due to their capability of directly monitoring physiological and ambient information. However, previous demonstrations usually lacked efficient sensor modalities, facile fabrication process, mechanical stability, or biocompatibility. Here, we demonstrate a flexible approach for fabrication of multifunctional smart contact lenses with an ultrathin MoS₂ transistors-based serpentine mesh sensor system. The integrated sensor systems contain a photodetector for receiving optical information, a glucose sensor for monitoring glucose level directly from tear fluid, and a temperature sensor for diagnosing potential corneal disease. Unlike traditional sensors and circuit chips sandwiched in the lens substrate, this serpentine mesh sensor system can be directly mounted onto the lenses and maintain direct contact with tears, delivering high detection sensitivity, while being mechanically robust and not interfering with either blinking or vision. Furthermore, the in vitro cytotoxicity tests reveal good biocompatibility, thus holding promise as next-generation soft electronics for healthcare and medical applications.

SERPINH1, Targeted by miR-29b, Modulated Proliferation and Migration of Human Retinal Endothelial Cells Under High Glucose Conditions

AIM

In the present study, we performed bioinformatics studies and in vitro functional assays to explore the underlying role of serpin family H member 1 (SERPINH1) in the diabetic retinopathy.

METHODS

Common differentially expressed genes (DEGs) between diabetic retinal tissues and normal retinal tissues were analyzed using Gene Expression Omnibus (GEO) database. The proliferation and migration of human retinal endothelial cells (HRECs) was evaluated by MTS, EdU and wound healing assays, respectively; the miRNA and mRNAs expression levels of hub genes in HRECs were determined using quantitative real-time PCR (qRT-PCR). Protein levels were determined using a Western blot assay.

RESULTS

A total of 189 common DEGs were screened between two GEO datasets (GSE60436 and GSE94019), and ten potential hub genes that may link to the progression of diabetic retinopathy were detected. The qRT-PCR results showed that collagen, type I, alpha 1 (COL1A1), Collagen, type I, alpha 2 (COL1A2) and serpin family H member 1 (SERPINH1) mRNA expression levels were up-regulated in the HRECs after being exposed to high glucose for 48 h. Silence of SERPINH1 repressed the high glucose-induced increase in proliferation and migration of HRECs. SERPINH1 was a target of miR-29b and was suppressed by miR-29 in HRECs. SERPINH1 overexpression promoted HREC proliferation and migration. Furthermore, miR-29b suppressed HREC proliferation and migration under high-glucose stimulation, which was significantly attenuated by enforced expression of SERPINH1.

CONCLUSION

In conclusion, by performing the integrated bioinformatics analysis, the present study suggested that 3 hub genes (COL1A1, COL1A2 and SERPINH1) may be associated with diabetic retinopathy pathophysiology. Further mechanistic studies indicated that miR-29b/SERPINH1 signaling participated in high glucose-induced enhancement in the proliferation and migration of HRECs.

Development of polydimethylsiloxane-based biomimetic scaffolds with cylinder micropillars for retinal pigment epithelial cell cultivation

BACKGROUND

Age-related macular degeneration (AMD) is one of the leading causes of vision loss. Once the retinal pigment epithelium (RPE) layers are destroyed, the poor visual acuity and recognition are generally irreversible. Cell therapy that possesses enormous potential in regenerative medicine may provide an alternative treatment for several incurable diseases such as AMD. In this study, we developed an innovative polydimethylsiloxane (PDMS)-based biomimetic scaffolds with cylinder micropillars for the cultivation of induced pluripotent stem cell-derived RPEs (iPSC-RPEs). RPEs were cultured on the PDMS-based biomimetic scaffolds and validated the cells gene expression.

METHODS

The biomimetic PDMS scaffold was fabricated through spin coating and lithography method. It was further modified on surface with biomolecules to improve cell affinity and stability. The iPSC-RPEs were seeded on the scaffold and analyzed with characteristic gene expression.

RESULTS

PDMS biomimetic scaffold was analyzed with Fourier transform infrared spectroscopy and proved its chemical composition. iPSC-RPEs demonstrated confluent cell monolayer on the scaffold and maintained RPE-specific gene expression, which proved the PDMS-based biomimetic scaffold to be supportive for iPSC-RPEs growth.

CONCLUSION

The PDMS interface allowed regular growth of iPSC-RPEs and the design of cylinder micropillars further provided the bioscaffold high motion resistance may improve the engraftment stability of iPSC-RPEs after transplantation. Taken together, this innovative PDMS-based biomimetic scaffold may serve as an ideal interface for in vitro iPSC-RPE cultivation and subsequent transplantation in vivo. This novel device exhibits better bioavailability than conventional injection of donor cells and may be an alternative option for the treatment of AMD.

A human retinal microvascular endothelial-pericyte co-culture model to study diabetic retinopathy in vitro

This human primary co-culture model using human retinal microvascular endothelial cells (hREC) and human retinal pericyte cells (hRP) aims to improve current understanding of the cellular changes occurring in the retinal microvasculature during diabetic retinopathy (DR). Currently, patients often present in clinic with late-stage DR, only when vision becomes impaired. Therefore, new strategies for earlier detection in clinic, combined with novel pharmaceutical and cellular interventions are essential in order to slow or halt the progression of DR from background to sight-threatening stage. This co-culture model can be used as a simple, replicable in vitro tool to discover and assess novel drug therapies and improve fundamental understanding of alterations to cell behaviour in the human retinal microvasculature during DR. hRP and hREC were cultured for up to 21 days in normoxic (20%) or hypoxic (2%) oxygen levels and physiological (5.5 mM) or very high (33 mM) glucose, to maintain a healthy, or induce a diabetic-like phenotype in vitro. Mono- or co-cultured hREC and hRP were seeded 1:1 in healthy (20% oxygen and 5.5 mM glucose) or diabetic-like (2% oxygen and 33 mM glucose) conditions, on either side of untreated polyethylene terephthalate (PET) transwell inserts, and cultured for 21 days. Mono- and co-cultures were analysed for changes in metabolic activity, angiogenic response and junctional protein expression, using immunofluorescence antibody labelling, flow cytometry and multiplex ELISA technology. hRP and hREC were successfully co-cultured, and the glucose and oxygen concentrations selected for the in vitro healthy and diabetic-like conditions were sufficient for cell viability and EC monolayer integrity, with evidence of an angiogenic response in diabetic-like conditions within the 21 day timeframe. Angiopoietin-2 (Ang-2), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) secretion were all increased, whilst hepatocyte growth factor (hHGF), tissue inhibitor for metalloproteinase-2 (TIMP-2) and interleukin-8 (IL-8) secretion were all reduced in the in vitro diabetic-like conditions. The secretion profile of co-cultures was different to mono-cultures, highlighting the importance of using co-culture models to collect data more reflective of the close relationship between hRP-hREC in vivo. Previous groups have developed useful co-culture models utilising non-human, immortalised or large vessel-sourced cells to explore changes to the vasculature during hypoxia and/or high glucose insult. In this study the use of human primary, retina-specific microvascular cells, mono- and co-cultured, collected over a longer culture period, has enabled detection of changes that may have been missed in previous models.

Development of an in vitro 3D choroidal neovascularization model using chemically induced hypoxia through an ultra-thin, free-standing nanofiber membrane

Choroidal neovascularization (CNV) is the pathological growth of new blood vessels in the sub-retinal pigment epithelial (RPE) space from the choroid through a break in the Bruch's membrane (BM). Despite its importance in studying biological processes and drug discovery, the development of an in vitro CNV model that achieves the physiological structures of native RPE-BM-choroidal capillaries (CC) is still challenging. Here, we develop a novel 3D RPE-BM-CC complex biomimetic system on an ultra-thin, free-standing nanofiber membrane. The thickness of the pristine nanofiber membrane is 2.17 ± 0.81 μm, and the Matrigel-coated nanofiber membrane attains a permeability coefficient of 2.95 ± 0.25 × 10^-6 cm/s by 40 kDa FITC-dextran, which is similar to the physiological value of the native BM. On the in vitro 3D RPE-BM-CC complex system, we demonstrate endothelial cell invasion across the 3D RPE-BM-CC complex and the mechanism of the invasion by imposing a hypoxic condition, which is thought to be the major pathological cause of CNV. Furthermore, alleviation of the invasion is achieved by treating with chrysin and anti-VEGF antibody. Thus, the in vitro 3D RPE-BM-CC complex biomimetic system can recapitulate essential features of the pathophysiological environment and be employed for the screening of drug candidates to reduce the number of costly and time-consuming in vivo tests or clinical trials.

Optimization of an in vitro bilayer model for studying the functional interplay between human primary retinal pigment epithelial and choroidal endothelial cells isolated from donor eyes

OBJECTIVE

The microenvironment of outer retina is largely regulated by retinal pigment epithelium (RPE) and choroid. Damage to either of these layers lead to the development of age related macular degeneration (AMD). A simplified cell culture model that mimics the RPE/Bruch's membrane (BM) and choroidal layers of the eye is a prerequisite for elucidating the molecular mechanism of disease progression.

RESULTS

We have isolated primary retinal pigment epithelial cells (hRPE) and human primary choroidal endothelial cells (hCEC) from donor eyes to construct a bilayer of hCEC/hRPE on transwell inserts. Secretion of VEGF in the insert grown bilayer was significantly higher (22 pg/ml) than hCEC monolayer (3 pg/ml). To mimic the disease condition the model was treated with 100 ng/ml of VEGF, which increased the permeability of bilayer for 20 kDa FITC dextran while addition of bevacizumab, a humanized anti-VEGF drug, reversed the effect. To conclude the transwell insert based human primary hCEC/hRPE bilayer model would be an ideal system for studying the disease mechanisms and the crosstalk between RPE and choroid. This model will also be useful in screening small molecules and performing drug permeability kinetics.

Establishment of pancreatic microenvironment model of ER stress: Quercetin attenuates β-cell apoptosis by invoking nitric oxide-cGMP signaling in endothelial cells

The involvement of endoplasmic reticulum (ER) stress in endothelial dysfunction and diabetes-associated complications has been well documented. Inhibition of ER stress represents a promising therapeutic strategy to attenuate endothelial dysfunction in diabetes. Recent attention has focused on the development of small molecule inhibitors of ER stress to maintain endothelial homeostasis in diabetes. Here we have developed a reliable, robust co-culture system that allows a study on the endothelial cells and pancreatic β-cells crosstalk under ER stress and validated using a known ER stress modulator, quercetin. Furthermore, sensitizing of endothelial cells by quercetin (25 μM) confers protection of pancreatic β-cells against ER stress through nitric oxide (NO^∙) signaling. In addition, increased intracellular insulin and NO^∙-mediated cyclic 3',5'-guanosine monophosphate (cGMP) levels in pancreatic β-cells further confirmed the mechanism of protection under co-culture system. In addition, the potential protein targets of quercetin against ER stress in the endothelial cells were investigated through proteomic profiling and its phosphoprotein targets through Bioplex analysis. On the whole, the developed in vitro co-culture set up can serve as a platform to study the signaling network between the endothelial and pancreatic β-cells as well as provides a mechanistic insight for the validation of novel ER stress modulators.

Effects of different hypoxia degrees on endothelial cell cultures-Time course study

INTRODUCTION

Exposure of the endothelial cells to hypoxia, the decrease in oxygen supply can trigger an endothelial response. This response is involved in inflammatory diseases, tumorigenesis, and also with the micro vascular damage associated with aging. The aim of our study was to determine the hypoxia/re-oxygenation induced response in vitro, using human umbilical vein endothelial cells (HUVEC) cultures, at different time points with focus on cell viability, apoptosis oxidative stress and angiogenesis stimulation.

MATERIALS AND METHODS

Cells were exposed to 10%, 5% or 0% O₂ for 6h, 12h, and 24h. Viability was measured through colorimetry, apoptosis - annexin V-FITC staining, DNA lesions (γH₂AX), endothelial activation (sICAM1), angiogenesis (HIF1α), oxidative stress (malondialdehyde, superoxidismutase and NFκB activation) were determined by ELISA, Western Blot and spectrophotometry.

RESULTS AND DISCUSSION

Hypoxia decreased viability, increased apoptosis, oxidative stress, endothelial activation and angiogenesis, depending on O₂ concentration and time exposure. Short exposures to 5% and 10% O₂, efficiently activated anti-apoptotic mechanisms through NFκB activation, HIF1α and γH₂AX related DNA damage repair pathways. However, severe hypoxia and longer exposures to mild hypoxia induced high oxidative stress related damage and eventually led to apoptosis, through strong increases of HIF1α and accumulating DNA lesions.

A microfluidic renal proximal tubule with active reabsorptive function

In the kidney, the renal proximal tubule (PT) reabsorbs solutes into the peritubular capillaries through active transport. Here, we replicate this reabsorptive function in vitro by engineering a microfluidic PT. The microfluidic PT architecture comprises a porous membrane with user-defined submicron surface topography separating two microchannels representing a PT filtrate lumen and a peritubular capillary lumen. Human PT epithelial cells and microvascular endothelial cells in respective microchannels created a PT-like reabsorptive barrier. Co-culturing epithelial and endothelial cells in the microfluidic architecture enhanced viability, metabolic activity, and compactness of the epithelial layer. The resulting tissue expressed tight junctions, kidney-specific morphology, and polarized expression of kidney markers. The microfluidic PT actively performed sodium-coupled glucose transport, which could be modulated by administration of a sodium-transport inhibiting drug. The microfluidic PT reproduces human physiology at the cellular and tissue levels, and measurable tissue function which can quantify kidney pharmaceutical efficacy and toxicity.

Biological Interaction Between Human Gingival Fibroblasts and Vascular Endothelial Cells for Angiogenesis: A Co-culture Perspective

Advancement in cell culture protocols, multidisciplinary research approach, and the need of clinical implication to reconstruct damaged or diseased tissues has led to the establishment of three-dimensional (3D) test systems for regeneration and repair. Regenerative therapies, including dental tissue engineering, have been pursued as a new prospect to repair and rebuild the diseased/lost oral tissues. Interactions between the different cell types, growth factors, and extracellular matrix components involved in angiogenesis are vital in the mechanisms of new vessel formation for tissue regeneration. In vitro pre-vascularization is one of the leading scopes in the tissue-engineering field. Vascularization strategies that are associated with co-culture systems have proved that there is communication between different cell types with mutual beneficial effects in vascularization and tissue regeneration in two-dimensional or 3D cultures. Endothelial cells with different cell populations, including osteoblasts, smooth muscle cells, and fibroblasts in a co-culture have shown their ability to advocate pre-vascularization. In this review, a co-culture perspective of human gingival fibroblasts and vascular endothelial cells is discussed with the main focus on vascularization and future perspective of this model in regeneration and repair.

A Critical Analysis of the Available In Vitro and Ex Vivo Methods to Study Retinal Angiogenesis

Angiogenesis is a biological process with a central role in retinal diseases. The choice of the ideal method to study angiogenesis, particularly in the retina, remains a problem. Angiogenesis can be assessed through in vitro and in vivo studies. In spite of inherent limitations, in vitro studies are faster, easier to perform and quantify, and typically less expensive and allow the study of isolated angiogenesis steps. We performed a systematic review of PubMed searching for original articles that applied in vitro or ex vivo angiogenic retinal assays until May 2017, presenting the available assays and discussing their applicability, advantages, and disadvantages. Most of the studies evaluated migration, proliferation, and tube formation of endothelial cells in response to inhibitory or stimulatory compounds. Other aspects of angiogenesis were studied by assessing cell permeability, adhesion, or apoptosis, as well as by implementing organotypic models of the retina. Emphasis is placed on how the methods are applied and how they can contribute to retinal angiogenesis comprehension. We also discuss how to choose the best cell culture to implement these methods. When applied together, in vitro and ex vivo studies constitute a powerful tool to improve retinal angiogenesis knowledge. This review provides support for researchers to better select the most suitable protocols in this field.

Microfluidic co-cultures of retinal pigment epithelial cells and vascular endothelial cells to investigate choroidal angiogenesis

Angiogenesis plays a critical role in many diseases, including macular degeneration. At present, the pathological mechanisms remain unclear while appropriate models dissecting regulation of angiogenic processes are lacking. We propose an in vitro angiogenesis process and test it by examining the co-culture of human retinal pigmental epithelial cells (ARPE-19) and human umbilical vein endothelial cells (HUVEC) inside a microfluidic device. From characterisation of the APRE-19 monoculture, the tight junction protein (ZO-1) was found on the cells cultured in the microfluidic device but changes in the medium conditions did not affect the integrity of monolayers found in the permeability tests. Vascular endothelial growth factor (VEGF) secretion was elevated under low glucose and hypoxia conditions compared to the control. After confirming the angiogenic ability of HUVEC, the cell-cell interactions were analyzed under lowered glucose medium and chemical hypoxia by exposing ARPE-19 cells to cobalt (II) chloride (CoCl₂). Heterotypic interactions between ARPE-19 and HUVEC were observed, but proliferation of HUVEC was hindered once the monolayer of ARPE-19 started breaking down. The above characterisations showed that alterations in glucose concentration and/or oxygen level as induced by chemical hypoxia causes elevations in VEGF produced in ARPE-19 which in turn affected directional growth of HUVEC.

Bridging the gap: microfluidic devices for short and long distance cell-cell communication

Cell-cell communication is a crucial component of many biological functions. For example, understanding how immune cells and cancer cells interact, both at the immunological synapse and through cytokine secretion, can help us understand and improve cancer immunotherapy. The study of how cells communicate and form synaptic connections is important in neuroscience, ophthalmology, and cancer research. But in order to increase our understanding of these cellular phenomena, better tools need to be developed that allow us to study cell-cell communication in a highly controlled manner. Some technical requirements for better communication studies include manipulating cells spatiotemporally, high resolution imaging, and integrating sensors. Microfluidics is a powerful platform that has the ability to address these requirements and other current limitations. In this review, we describe some new advances in microfluidic technologies that have provided researchers with novel methods to study intercellular communication. The advantages of microfluidics have allowed for new capabilities in both single cell-cell communication and population-based communication. This review highlights microfluidic communication devices categorized as "short distance", or primarily at the single cell level, and "long distance", which mostly encompasses population level studies. Future directions and translation/commercialization will also be discussed.

Combined regimen of photodynamic therapy mediated by Gallium phthalocyanine chloride and Metformin enhances anti-melanoma efficacy

BACKGROUND

Melanoma therapy is challenging, especially in advanced cases, due to multiple developed tumor defense mechanisms. Photodynamic therapy (PDT) might represent an adjuvant treatment, because of its bimodal action: tumor destruction and immune system awakening. In this study, a combination of PDT mediated by a metal substituted phthalocyanine-Gallium phthalocyanine chloride (GaPc) and Metformin was used against melanoma. The study aimed to: (1) find the anti-melanoma efficacy of GaPc-PDT, (2) assess possible beneficial effects of Metformin addition to PDT, (3) uncover some of the mechanisms underlining cell killing and anti-angiogenic effects.

METHODS

Two human lightly pigmented melanoma cell lines: WM35 and M1/15 subjected to previous Metformin exposure were treated by GaPc-PDT. Cell viability, death mechanism, cytoskeleton alterations, oxidative damage, were assessed by means of colorimetry, flowcytometry, confocal microscopy, spectrophotometry, ELISA, Western Blotting.

RESULTS

GaPc proved an efficient photosensitizer. Metformin addition enhanced cell killing by mechanisms dependent on the cell line, namely apoptosis in the metastatic M1/15 and necrosis in the radial growth phase, WM35. Cell death mechanism relied on the inhibition of nuclear transcription factor (NF)-κB activation and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) sensitization, leading to TRAIL and TNF-α induced apoptosis. Metformin diminished the anti-angiogenic effect of PDT.

CONCLUSIONS

Metformin addition to GaPc-PDT increased tumor cell killing through enhanced oxidative damage and induction of proapoptotic mechanisms, but altered PDT anti-angiogenic effects.

GENERAL SIGNIFICANCE

Combination of Metformin and PDT might represent a solution to enhance the efficacy, leading to a potential adjuvant role of PDT in melanoma therapy.

Embryonic stem cell-derived neural progenitors transplanted to the hippocampus migrate on host vasculature

This study describes the migration of transplanted ESNPs either injected directly into the hippocampus of a mouse, seeded onto hippocampal slices, or under in vitro culture conditions. We show that transplanted mouse ESNPs associate with, and appear to migrate on the surface of the vasculature, and that human ESNPs also associate with blood vessels when seeded on hippocampal slices, and migrate towards BECs in vitro using a Boyden chamber assay. This initial adhesion to vessels is mediated, at least in part, via the integrin α6β1, as observed for SVZ neural progenitor cells. Our data are consistent with CXCL12, expressed by the astroglial-vasculature niche, playing an important role in the migration of transplanted neural progenitors within and outside of the hippocampus.

In vitro anti-angiogenic effects of Hemidesmus indicus in hypoxic and normoxic conditions

ETHNOPHARMACOLOGICAL RELEVANCE

The decoction of the roots of Hemidesmus indicus is widely used in the Indian traditional medicine for many purposes and poly-herbal preparations containing Hemidesmus are often used by traditional medical practitioners for the treatment of cancer. In the context of anticancer pharmacology, anti-angiogenic therapy has become an effective strategy for inhibiting new vessel formation and contrast tumor growth. These considerations are supported by the evidence that most tumors originate in hypoxic conditions and limitation of oxygen diffusion stimulates the formation of tumor abnormal microvasculature. Aim of this study was to evaluate the in vitro anti-angiogenic potential of Hemidesmus indicus (0.31-0.93 mg/mL) on human umbilical vein endothelial cells and delineate the main molecular mechanisms involved in its anti-angiogenic activity both in normoxia and hypoxia.

MATERIALS AND METHODS

The decoction of Hemidesmus indicus was subjected to an extensive HPLC phytochemical characterization. Its in vitro anti-angiogenic potential was investigated in normoxia and hypoxia. Cell proliferation, apoptosis induction, and inhibition of endothelial cell migration and invasion were analyzed by flow cytometry. The endothelial tube formation assay was evaluated in matrix gel. The capillary tube branch points formed were counted using a Motic AE21 microscope and a VisiCam videocamera. The regulation of key factors of the neovascularization process such as VEGF, HIF-1α and VEGFR-2 was explored at mRNA and protein level by real time PCR and flow cytometry, respectively.

RESULTS

Treatment with Hemidesmus resulted in a significant inhibition of cell proliferation and tube formation in both normoxia and hypoxia. Hemidesmus differently regulated multiple molecular targets related to angiogenesis according to oxygen availability. In normoxia, the inhibition of VEGF was the main responsible for its anti-angiogenic effect; the angiogenesis inhibition induced in hypoxia was regulated by a more complex mechanism involving firstly HIF-1α inhibition, and then VEGF and VEGFR-2 down-regulation. Additionally, the inhibition of endothelial cell migration and invasion by Hemidesmus was more pronounced in normoxia than in hypoxia, possibly due to the physiological enhanced induction of invasion characteristic of hypoxia.

CONCLUSIONS

Our results indicate that Hemidesmus might represent a promising therapeutic strategy for diseases in which the inhibition of angiogenesis could be beneficial, such as cancer. The antiangiogenic activity of Hemidesmus is based on multiple interactions with critical steps in the angiogenic cascade. VEGF expression stimulated by HIF-1α as well as endothelial cell migration and differentiation represent important targets of Hemidesmus action and might contribute to its cancer therapeutic efficacy that is presently emerging and offer a scientific basis for its use in traditional medicine.

Reconstruction of vascular structure with multicellular components using cell transfer printing methods

Natural vessel has three types of concentric cell layers that perform their specific functions. Here, the fabrication of vascular structure is reported by transfer printing of three different cell layers using thermosensitive hydrogels. Tetronic-tyramine and RGD peptide are co-crosslinked to prepare cell adhesive and thermosensitive hydrogels. The hydrogel increases its diameter by 1.26 times when the temperature reduces from 37 °C to 4 °C. At optimized seeding density, three types of cells form monolayers on the hydrogel, which is then transferred to the target surface within 3 min. Three monolayers are simultaneously transferred on one substrate with controlled shape and arrangement. The same approach is applied onto nanofiber scaffolds that are cultured for more than 5 d. Every type of monolayer shows proliferation and migration on nanofiber scaffolds, and the formation of robust cell-cell contact is revealed by CD31 staining in endothelial cell layer. A vascular structure with multicellular components is fabricated by transfer of three monolayers on nanofibers that are manually rolled with the diameter and length of the tube being approximately 3 mm and 12 mm, respectively. Collectively, it is concluded that the tissue transfer printing is a useful tool for constructing a vascular structure and mimicking natural structure of different types of tissues.

NG2 proteoglycan promotes tumor vascularization via integrin-dependent effects on pericyte function

The NG2 proteoglycan stimulates the proliferation and migration of various immature cell types, including pericytes. However, the role of NG2 in mediating pericyte/endothelial cell interaction has been less clear. In this study, we show that pericyte-specific NG2 ablation causes several structural deficits in blood vessels in intracranial B16F10 melanomas, including decreased pericyte ensheathment of endothelial cells, diminished formation of endothelial junctions, and reduced assembly of the vascular basal lamina. These deficits result in decreased tumor vessel patency, increased vessel leakiness, and increased intratumoral hypoxia. NG2-dependent mechanisms of pericyte interaction with endothelial cells are further explored in pericyte/endothelial cell co-cultures. siRNA-mediated NG2 knockdown in pericytes leads to reduced formation of pericyte/endothelial networks, reduced formation of ZO-1 positive endothelial cell junctions, and increased permeability of endothelial cell monolayers. We also show that NG2 knockdown results in loss of β1 integrin activation in endothelial cells, revealing a mechanism for NG2-dependent cross talk between pericytes and endothelial cells.