Primary Adhesion Research Articles

Enhancement of Zyxin Promotes Skin Fibrosis by Regulating FAK/PI3K/AKT and TGF-β Signaling Pathways via Integrins.

Skin fibrosis is a common pathological manifestation in systemic sclerosis (SSc), keloid, and localized scleroderma (LS) characterized by fibroblast activation and excessive extracellular matrix (ECM) deposition. However, few effective drugs are available to treat skin fibrosis due to its unclear mechanisms. In our study, we reanalyzed skin RNA-sequencing data of Caucasian, African, and Hispanic SSc patients from the Gene Expression Omnibus (GEO) database. We found that the focal adhesion pathway was up-regulated and Zyxin appeared to be the primary focal adhesion protein involved in skin fibrosis, and we further verified its expression in Chinese skin tissues of several fibrotic diseases, including SSc, keloid, and LS. Moreover, we found Zyxin inhibition could significantly alleviate skin fibrosis using Zyxin knock-down and knock-out mice, nude mouse model and skin explants of human keloid. Double immunofluorescence staining showed that Zyxin was highly expressed in fibroblasts. Further analysis revealed pro-fibrotic gene expression and collagen production increased in Zyxin over-expressed fibroblasts, and decreased in Zyxin interfered SSc fibroblasts. In addition, transcriptome and cell culture analyses revealed Zyxin inhibition could effectively attenuate skin fibrosis by regulating the FAK/PI3K/AKT and TGF-β signaling pathways via integrins. These results suggest Zyxin appears a potential new therapeutic target for skin fibrosis.

ANALYSIS OF PERMANENT MAGNETIC-BASED CLIMBING ROBOT DESIGN FOR SHIP HULL AND OIL TANK SERVICES

Servicing operations in the marine and oilfield industries cover a wide range of tasks, including the removal of biofoulings from ship surfaces, re-painting, and inspection of ship and oil tank surfaces, as both are exposed to the environment. With the rate at which technology has advanced, a modern solution to this challenge may be attainable in assisting manual labour. This paper outlines the development of a robot that climbs a wall at an angle adopting a permanent magnet as the primary adhesion mechanism. Attachable and detachable permanent magnets are used in the robot design to demonstrate how the increments of magnet number affect the climbing of the robot at an angle. The analysis of this experiment includes static and dynamic movement of the robot and a discussion related to the experiment is included in the paper.

Multifaceted polymeric nerve guidance conduits with distinctive double-layered architecture and plasma-induced inner chemistry gradient for the repair of critical-sized defects

Despite tissue engineering advances, current nerve guidance conduits (NGCs) are still failing in repairing critical-sized defects. This study aims, therefore, at tackling large nerve gaps (2 cm) by designing NGCs possessing refined physicochemical properties enhancing the activity of Schwann cells (SCs) that support nerve regeneration over long distances. As such, a combinatorial strategy adopting novel plasma-induced surface chemistry and architectural heterogeneity was considered. A mechanically suitable copolymer (Polyactive®) was electrospun to produce nanofibrous NGCs mimicking the extracellular matrix. An innovative seamless double-layered architecture consisting of an inner wall comprised of bundles of aligned fibers with intercalated random fibers and an outer wall fully composed of random fibers was conceived to synergistically provide cell guidance cues and sufficient nutrient inflow. NGCs were subjected to argon plasma treatments using a dielectric barrier discharge (DBD) and a plasma jet (PJ). Surface chemical changes were examined by advanced X-ray photoelectron spectroscopy (XPS) micro-mappings. The DBD homogeneously increased the surface oxygen content from 17 % to 28 % on the inner wall. The PJ created a gradient chemistry throughout the inner wall with an oxygen content gradually increasing from 21 % to 30 %. In vitro studies revealed enhanced primary SC adhesion, elongation and proliferation on plasma-treated NGCs. A cell gradient was observed on the PJ-treated NGCs thus underlining the favorable oxygen gradient in promoting cell chemotaxis. A gradual change from circular to highly elongated SC morphologies mimicking the bands of Büngner was visualized along the gradient. Overall, plasma-treated NGCs are promising candidates paving the way towards critical nerve gap repair.

A Core-Shell Approach for Systematically Coarsening Nanoparticle-Membrane Interactions: Application to Silver Nanoparticles.

The continuous release of engineered nanomaterial (ENM) into the environment may bring about health concerns following human exposure. One important source of ENMs are silver nanoparticles (NPs) that are extensively used as anti-bacterial additives. The introduction of ENMs into the human body can occur via ingestion, skin uptake or the respiratory system. Therefore, evaluating how NPs translocate over bio-membranes is essential in assessing their primary toxicity. Unfortunately, data regarding membrane-NP interaction is still scarce, as is theoretical and in silico insight into what governs adhesion and translocation for the most relevant NPs and membranes. Coarse-grained (CG) molecular descriptions have the potential to alleviate this situation, but are hampered by the absence of a direct link to NP materials and membrane adhesion mechanisms. Here, we interrogate the relationship between the most common NP representation at the CG level and the adhesion characteristics of a model lung membrane. We find that this representation for silver NPs is non-transferable, meaning that a proper CG representation for one size is not suited for other sizes. We also identify two basic types of primary adhesion-(partial) NPs wrapping by the membrane and NP insertion into the membrane-that closely relate to the overall NP hydrophobicity and significantly differ in terms of lipid coatings. The proven non-transferability of the standard CG representation with size forms an inspiration for introducing a core-shell model even for bare NPs that are uniform in composition. Using existing all-atom molecular dynamics (MD) data as a reference, we show that this extension does allow us to reproduce size-dependent NP adhesion properties and lipid responses to NP binding at the CG level. The subsequent CGMD evaluation for 10 nm Ag NPs provides new insight into membrane binding for relevant NP sizes and into the role of water in trapping NPs into defected mixed monolayer-bilayer states. This development will be instrumental for simulating NP-membrane adhesion towards more experimentally relevant length and time scales for particular NP materials.

Adhesion-Deformation-Hydrodynamic model of friction and wear

The proposed Adhesion-Deformation-Hydrodynamic model of friction and wear is based on the relationship of elastic-deformation processes in the surfaces of curvilinear contacts with hydrodynamic regular processes of extrusion and rarefaction in lubricating layers in tribocontacts, as well as with the processes of primary adhesion of friction surfaces and subsequent acts of adhesive wear. The proposed Adhesion-Deformation-Hydrodynamic model of friction and wear and its main provisions on the relationship between extrusion, rarefaction in lubricating layers and primary adhesion of friction surfaces of curvilinear contacts cover the entire load-speed range and all modes of lubrication of friction surfaces

Silk Fibroin-Based Bioengineered Scaffold for Enabling Hemostasis and Skin Regeneration of Critical-Size Full-Thickness Heat-Induced Burn Wounds.

Millions of people around the globe are affected by full-thickness skin injuries. A delay in the healing of such injuries can lead to the formation of chronic wounds, posing several clinical and economic challenges. Current strategies for wound care aim for skin regeneration and not merely skin repair or faster wound closure. The present study aimed to develop a bioactive wound-healing matrix comprising natural biomaterial silk fibroin (SF), clinical-grade human fibrin (FIB), and human hyaluronic acid (HA), resulting in SFFIBHA for regeneration of full-thickness burn wounds. A porous, hemostatic, self-adhesive, moisture-retentive, and biomimetic scaffold that promotes healing was the expected outcome. The study validated a terminal sterilization method, suggesting the stability and translational potential of the novel scaffold. Also, the study demonstrated the regenerative abilities of scaffolds using in vitro cell culture experiments and in vivo full-thickness burn wounds of critical size (4 cm × 4 cm) in a rabbit model. Under in vitro conditions, the scaffold enhanced primary dermal fibroblast adhesion and cell proliferation with regulated extracellular matrix (ECM) synthesis. In vivo, the scaffolds promoted healing with mature epithelium coverage involving intact basal cells, superficial keratinocytes, multilayers of keratohyalin, dermal regeneration with angiogenesis, and deposition of remodeled ECM in 28 days. The relative gene expression of the IL6 marker indicated transitions from inflammation to proliferation stage. In addition, we observed skin appendages and rete peg development in the SFFIBHA-treated wound tissues. Although wound closure was observed, neither negative (untreated/sham) nor positive (commercially available product; NeuSkin) control wounds developed skin appendages/rete pegs or native skin architecture. After 56 days, healing with organized ECM production enabled the recovery of mechanical properties of skin with higher tissue maturity in SFFIBHA-treated wounds. Thus, in a single application, the SFFIBHA scaffold proved to be an efficient biomimetic matrix that can guide burn wound regeneration. The developed matrix is a suture-less, hemostatic, off-the-shelf product for potential wound regenerative applications.

The Role of Nanoscale Distribution of Fibronectin in the Adhesion of Staphylococcus aureus Studied by Protein Patterning and DNA-PAINT.

Staphylococcus aureus is a widespread and highly virulent pathogen that can cause superficial and invasive infections. Interactions between S. aureus surface receptors and the extracellular matrix protein fibronectin mediate the bacterial invasion of host cells and is implicated in the colonization of medical implant surfaces. In this study, we investigate the role of distribution of both fibronectin and cellular receptors on the adhesion of S. aureus to interfaces as a model for primary adhesion at tissue interfaces or biomaterials. We present fibronectin in patches of systematically varied size (100–1000 nm) in a background of protein and bacteria rejecting chemistry based on PLL-g-PEG and studied S. aureus adhesion under flow. We developed a single molecule imaging assay for localizing fibronectin binding receptors on the surface of S. aureus via the super-resolution DNA points accumulation for imaging in nanoscale topography (DNA-PAINT) technique. Our results indicate that S. aureus adhesion to fibronectin biointerfaces is regulated by the size of available ligand patterns, with an adhesion threshold of 300 nm and larger. DNA-PAINT was used to visualize fibronectin binding receptor organization in situ at ∼7 nm localization precision and with a surface density of 38–46 μm–2, revealing that the engagement of two or more receptors is required for strong S. aureus adhesion to fibronectin biointerfaces.

Sustainable preparation of spherical amphoteric organics:Isoelectric point-spherical agglomeration technology

This work developed a sustainable and highly-efficient isoelectric point-spherical agglomeration (IPSA) technology for preparing spherical particles of amphoteric organics. The IPSA technology couples isoelectric point crystallization and spherical agglomeration (SA), eliminating the most polluting part in SA technology, i.e. the use of solvents and anti-solvents, and also achieving multiple recycling of mother liquor for the first time. It thereby reducing the amount of organic solvents by approximately 60% compared with SA technology. The mechanism of the IPSA technology was studied by in-situ process analysis tools, which included phase separation, crystallization, wetting, primary adhesion, secondary adhesion and consolidation. Then, the mother liquor recycling experiments of IPSA process were designed based on three model substances of L-tryptophan, L-leucine and L-methionine respectively, which verified the sustainability of IPSA technology. In addition, the effects of the BSR (bridging liquid/solute volume ratio), agitation rate and alkali dropping rate were investigated to determine the optimal parameters.

Functional composite microbeads for cell-based meat culture: effect of animal gelatin coating on cell proliferation and differentiation

Hydrogel microbeads are promising matrices for cell-based meat culture because they can be conveniently fabricated from food-grade materials. In this study, food-grade sodium alginate was successfully applied to fabricate edible microbeads with the desired diameters (∼200 µm) using electrospray technology. Pure alginate microbeads have poor cytoaffinity. To enhance the cytoaffinity of alginate microbeads for meat culture, we applied different gelatin coatings, namely porcine gelatin, bovine gelatin, and fish gelatin, onto alginate beads. The modification is non-toxic and environmentally friendly with the use of plant-derived crosslinkers and under mild reaction conditions. As all ingredients are food grade, the modified microbeads are edible and biodegradable, with the mean diameters of 142.96 ± 35.49 μm (porcine gelatin-coated beads), 105.12 ± 80.46 μm (bovine gelatin-coated beads), and 94.81 ± 67.38 μm (bovine gelatin-coated beads). These modified microbeads have self-fluorescence and can be easily distinguished under a fluorescent microscope. The hydrogel core enables the microbeads to have a density of 1.04 g cm−3 for suspension culture. Bovine gelatin-coated microbeads have the best primary porcine myoblast and C2C12 cell adhesion, and can achieve between 16- to 18-fold proliferation of different muscle cells. With the successful differentiation of C2C12 and proliferation of 3T3-L1 adipocytes on bovine gelatin-coated microbeads, cells and microbeads can form clusters, illustrating that our edible microbeads are promising microcarriers for mammalian cell culture for cell-based meat production.

Biliverdin reductase bridges focal adhesion kinase to Src to modulate synaptic signaling.

Synapses connect discrete neurons into vast networks that send, receive, and encode diverse forms of information. Synaptic function and plasticity, the neuronal process of adapting to diverse and variable inputs, depend on the dynamic nature of synaptic molecular components, which is mediated in part by cell adhesion signaling pathways. Here, we found that the enzyme biliverdin reductase (BVR) physically links together key focal adhesion signaling molecules at the synapse. BVR-null (BVR-/-) mice exhibited substantial deficits in learning and memory on neurocognitive tests, and hippocampal slices in which BVR was postsynaptically depleted showed deficits in electrophysiological responses to stimuli. RNA sequencing, biochemistry, and pathway analyses suggested that these deficits were mediated through the loss of focal adhesion signaling at both the transcriptional and biochemical level in the hippocampus. Independently of its catalytic function, BVR acted as a bridge between the primary focal adhesion signaling kinases FAK and Pyk2 and the effector kinase Src. Without BVR, FAK and Pyk2 did not bind to and stimulate Src, which then did not phosphorylate the N-methyl-d-aspartate (NMDA) receptor, a critical posttranslational modification for synaptic plasticity. Src itself is a molecular hub on which many signaling pathways converge to stimulate NMDAR-mediated neurotransmission, thus positioning BVR at a prominent intersection of synaptic signaling.

Poly-l-lysine/Laminin Surface Coating Reverses Glial Cell Mechanosensitivity on Stiffness-Patterned Hydrogels.

Brain tissues demonstrate heterogeneous mechanical properties, which evolve with aging and pathologies. The observation in these tissues of smooth to sharp rigidity gradients raises the question of brain cell responses to both different values of rigidity and their spatial variations, in dependence on the surface chemistry they are exposed to. Here, we used recent techniques of hydrogel photopolymerization to achieve stiffness texturing down to micrometer resolution in polyacrylamide hydrogels. We investigated primary neuron adhesion and orientation as well as glial cell proliferative properties on these rigidity-textured hydrogels for two adhesive coatings: fibronectin or poly-l-lysine/laminin. Our main observation is that glial cell adhesion and proliferation is favored on the stiffer regions when the adhesive coating is fibronectin and on the softer ones when it consists of poly-l-lysine/laminin. This behavior was unchanged by the presence or the absence of neuronal cells. In addition, glial cells were not confined by sharp, micron-scaled gradients of rigidity. Our observations suggest that rigidity sensing could involve adhesion-related pathways that profoundly depend on surface chemistry.

Insight into the Structure, Functions, and Dynamics of the Leptospira Outer Membrane Proteins with the Pathogenicity.

Leptospirosis is a widespread zoonosis that frequently occurs in tropical and subtropical countries. Leptospira enters the host through wounds or mucous membranes and spreads to the whole body through the blood, causing systemic infection. Kidneys are the preferential site where Leptospira accumulates, especially in the renal interstitium and renal tubule epithelial cells. Clinical symptoms in humans include high fever, jaundice, renal failure, and severe multiple-organ failure (Weil’s syndrome). Surface-exposed antigens are located at the outermost layer of Leptospira and these potential virulence factors are likely involved in primary host-pathogen interactions, adhesion, and/or invasion. Using the knockout/knockdown techniques to the evaluation of pathogenicity in the virulence factor are the most direct and effective methods and many virulence factors are evaluated including lipopolysaccharides (LPS), Leptospira lipoprotein 32 (LipL32), Leptospira ompA domain protein 22 (Loa22), LipL41, LipL71, Leptospira immunoglobulin-like repeat A (LigA), LigB, and LipL21. In this review, we will discuss the structure, functions, and dynamics of these virulence factors and the roles of these virulence factors in Leptospira pathogenicity. In addition, a protein family with special Leucine-rich repeat (LRR) will also be discussed for their vital role in Leptospira pathogenicity. Finally, these surface-exposed antigens are discussed in the application of the diagnosis target for leptospirosis and compared with the serum microscope agglutination test (MAT), the gold standard for leptospirosis.

Antiplatelet Agents Affecting GPCR Signaling Implicated in Tumor Metastasis.

Metastasis requires that cancer cells survive in the circulation, colonize distant organs, and grow. Despite platelets being central contributors to hemostasis, leukocyte trafficking during inflammation, and vessel stability maintenance, there is significant evidence to support their essential role in supporting metastasis through different mechanisms. In addition to their direct interaction with cancer cells, thus forming heteroaggregates such as leukocytes, platelets release molecules that are necessary to promote a disseminating phenotype in cancer cells via the induction of an epithelial–mesenchymal-like transition. Therefore, agents that affect platelet activation can potentially restrain these prometastatic mechanisms. Although the primary adhesion of platelets to cancer cells is mainly independent of G protein-mediated signaling, soluble mediators released from platelets, such as ADP, thromboxane (TX) A2, and prostaglandin (PG) E2, act through G protein-coupled receptors (GPCRs) to cause the activation of more additional platelets and drive metastatic signaling pathways in cancer cells. In this review, we examine the contribution of the GPCRs of platelets and cancer cells in the development of cancer metastasis. Finally, the possible use of agents affecting GPCR signaling pathways as antimetastatic agents is discussed.

3D-printed porous Ti6Al4V alloys with silver coating combine osteocompatibility and antimicrobial properties

Additive manufacturing allows for the production of porous metallic implants for use in orthopaedics, providing excellent mechanical stability and osseointegration. However, the increased surface area of such porous implants also renders them susceptible to bacterial colonization. In this work, two trabecular porous Ti6Al4V alloys produced by electron beam melting were investigated for their osteocompatibility and antimicrobial effects, comparing samples with a silver-coated surface to uncoated samples. Dense grit-blasted Ti samples were used for comparison. The porous samples had pore sizes of 500–600 μm and 5 to 10 μm surface roughness, the silver-coated samples contained 7 at.% Ag, resulting in a cumulative Ag release of 3.5 ppm up to 28 days. Silver reduced the adhesion of Staphylococcus aureus to porous samples and inhibited 72 h biofilm formation by Staphylococcus epidermidis but not that of S. aureus. Primary human osteoblast adhesion, proliferation and differentiation were not impaired in the presence of silver, and expression of osteogenic genes as well as production of mineralized matrix were similar on silver-coated and uncoated samples. Our findings indicate that silver coating of porous titanium implants can achieve antimicrobial effects without compromising osteocompatibility, but higher silver contents may be needed to yield a sustained protection against fast-growing bacteria.

Removal effect and mechanism of amphiphilic chitosan modified microbubbles on microcystis aeruginosa

Algal blooms in lake and reservoir water lead to water quality problems, including water odors, algal toxins, and disinfection byproducts. A novel dissolved air flotation process that incorporates positively charged bubbles (PosiDAF) can effectively remove algae in lakes and reservoirs. Chitosan, as a modified bubble agent in the PosiDAF process, has attracted extensive attention due to its natural nontoxicity and good flocculation properties. In this paper, three types of amphiphilic chitosan with different lengths of carbon chains were prepared via amphiphilic modification and were used as bubble modifiers to remove microcystis aeruginosa in the PosiDAF process. The effects of algae removal under different dosage of modifiers were compared, and the role of algal organic matter was investigated. Results showed that the water solubility of chitosan was markedly enhanced after amphiphilic modification, while thermal stability were decreased. When using butyl-N-2 hydroxypropyl trimethyl chitosan ammonium chloride (C4-HTCC), the effect of modified air flotation was the best, and the removal ratio of algae was 93.47% when the C4-HTCC dosage was 1.0 mg/L. The presence of AOM enhanced the overall effect of algae removal, and electrostatic attraction was the primary adhesion mechanism of the microbubble-amphiphilic chitosan-algal organic matter-algal cell system. In addition, adsorption bridging and net trapping also have positive effects on algae removal.

Baicalin inhibits biofilm formation by influencing primary adhesion and aggregation phases in Staphylococcus saprophyticus

The ability to form biofilms on surfaces makes Staphylococcus saprophyticus (S. saprophyticus) becomes the main pathogenic factor in nosocomial infections. Previously, we demonstrated that baicalin (Bac) inhibited azithromycin-resistant S. saprophyticus (ARSS) biofilm formation. This investigation aims to explore the influence of baicalin on primary adhesion and aggregation phases of biofilm formation, and the treatment effect of baicalin and azithromycin on ARSS biofilm-associated infection. Crystal violet (CV) staining and scanning electron microscope (SEM) observations clearly showed that sub-inhibitory concentration baicalin inhibited ARSS biofilm formation when baicalin was added before the adhesion and aggregation phases. Baicalin significantly increased the relative adhesion inhibition rate and decreased the rate of bacteria aggregation in a dose-dependent manner. Moreover, CLSM and cell lysis assays revealed that baicalin inhibited the production of surface proteins and cell autolysis in bacteria adhesion and aggregation phases of biofilm formation. Meanwhile, the relative expressions of adhesion-related and autolysis-related genes were down-regulated by baicalin. In vivo, the combination of baicalin and azithromycin succeeded in eradicating ARSS from the mouse cutaneous infection model and decreasing the pathological injuries, the expressions of cytokines in infected tissue, and the number of inflammatory cells in the blood. Simultaneously, baicalin decreased the bacterial burdens in tubes, the level of TNF-α, and the number of monocytes and neutrophils compared with that of the SS and azithromycin groups. Based on these results, baicalin inhibited the adhesion and aggregation phases of biofilm formation by influenced the production of surface proteins and cell autolysis. Baicalin and azithromycin synergetically treated ARSS biofilm-associated infection.

To Bleed or Not to Bleed: MCS-Related Shear Stress Promotes Redistribution of GPIb and αIIbβ3 from Platelets to Microparticles Thus Impairing Platelet Hemostatic Function

Purpose Bleeding is a leading cause of readmission and 1-year mortality for mechanical circulatory support (MCS) patients. Mechanical damage of platelets and coagulation proteins induced by MCS-generated high shear stress is the main driver of bleeding. We previously demonstrated that hypershear promotes platelet pro-apoptotic behavior resulting in membrane reorganization and generation of platelet-derived microparticles (PDMP). Here, we test the hypothesis that hypershear alters surface expression and shedding of adhesion receptors GPIb and αIIbβ3 from platelets and PDMPs thus affecting platelet aggregability - all potential bleeding contributors. Methods Human platelets were exposed to shear stress in a hemodynamic shearing device (30-70 dyn/cm2, 10 min). Integrin GPIb and αIIbβ3 surface expression and PDMP generation were quantified by flow cytometry. Single platelets and PDMPs were distinguished by FS/SS characteristics. Shedding of soluble GPIb and αIIbβ3 fragments was quantified by ELISA. Platelet aggregation was measured by optical aggregometry. Results Platelet exposure to hypershear led to a reduction of platelet GPIb surface expression, with a significant drop of GPIb+ platelet number and fluorescence (73.5 ± 2.9% and 953.1 ± 101.0 AU vs. 94.3 ± 0.7% and 1620 ± 72.4 AU for intact platelets; M ± SEM, ANOVA, p ≤ 0.05). Yet, no shear-mediated shedding of soluble GPIb fragment or β3 subunit was found. Downregulation of platelet GPIb expression coincided with a progressive increase of GPIb- & αIIbβ3-positive PDMPs after shear (up to 3.3 ± 0.6% & 12.5 ± 2.8%, correspondingly). Surface density of GPIb and αIIbβ3 on PDMPs was 2-4x higher than on platelets, post-shear. Platelet aggregation to increasing concentrations of ADP and TRAP-6 was significantly impaired by 70 dyn/cm2 shear stress. Conclusion MCS-mediated hypershear and platelet stress accumulation 1) induces downregulation of platelet adhesion receptors via ejection of receptor-enriched PDMPs; 2) does not induce shedding of soluble fragments of GPIb and β3, and; 3) mechanistically limits platelet aggregatory and hemostatic responses. Shear-mediated redistribution of primary adhesion receptors from platelets to PDMPs coupled with impaired aggregability may mechanistically contribute to MCS-related bleeding.

Platelet Dysfunction During Mechanical Circulatory Support: Elevated Shear Stress Promotes Downregulation of αIIbβ3 and GPIb via Microparticle Shedding Decreasing Platelet Aggregability.

[Figure: see text].

Surface Modification of PDMS-Based Microfluidic Devices with Collagen Using Polydopamine as a Spacer to Enhance Primary Human Bronchial Epithelial Cell Adhesion.

Polydimethylsiloxane (PDMS) is a silicone-based synthetic material used in various biomedical applications due to its properties, including transparency, flexibility, permeability to gases, and ease of use. Though PDMS facilitates and assists the fabrication of complicated geometries at micro- and nano-scales, it does not optimally interact with cells for adherence and proliferation. Various strategies have been proposed to render PDMS to enhance cell attachment. The majority of these surface modification techniques have been offered for a static cell culture system. However, dynamic cell culture systems such as organ-on-a-chip devices are demanding platforms that recapitulate a living tissue microenvironment’s complexity. In organ-on-a-chip platforms, PDMS surfaces are usually coated by extracellular matrix (ECM) proteins, which occur as a result of a physical and weak bonding between PDMS and ECM proteins, and this binding can be degraded when it is exposed to shear stresses. This work reports static and dynamic coating methods to covalently bind collagen within a PDMS-based microfluidic device using polydopamine (PDA). These coating methods were evaluated using water contact angle measurement and atomic force microscopy (AFM) to optimize coating conditions. The biocompatibility of collagen-coated PDMS devices was assessed by culturing primary human bronchial epithelial cells (HBECs) in microfluidic devices. It was shown that both PDA coating methods could be used to bind collagen, thereby improving cell adhesion (approximately three times higher) without showing any discernible difference in cell attachment between these two methods. These results suggested that such a surface modification can help coat extracellular matrix protein onto PDMS-based microfluidic devices.

Ovariopexy-Before and after Endometriosis Surgery.

Endometriosis surgery is often very challenging. Key to complete resection of endometriosis is access to the retroperitoneum. Endometriosis can involve the ureter and uterine vessels, and ovary on the lateral pelvic wall makes retroperitoneal access difficult. Primary and post-surgical adhesions prevalence in endometriosis is very high. Ovariopexy, transposition of ovaries temporarily, is done for better surgical access and to reduce postoperative adhesions. We concluded that although limited evidence, ovariopexy is an excellent tool to aid endometriosis surgery and prevent postoperative adhesions. It is cost effective, simple and complication rate almost nil. More robust trials are required to substantiate evidence for its impact on preventing postoperative adhesions and its effect on fertility. In this review, we describe our technique of ovariopexy supplemented with a video, with the aim to put light on this useful and important technique, which is beneficial both for surgeons and patients.