Interactions between whole blood and hydrophilic or hydrophobic glass surfaces: kinetics of cell adhesion

Design of buffer property for the new enrichment method of circulating tumor cell based on immunomagnetic-negative separation

Metastasis is a significant contributor to cancer-related mortality and a critical issue in cancer. Monitoring the changes in circulating tumor cells (CTCs) with metastatic potential is a valuable prognostic and predictive biomarker. CTCs are a rare population in the peripheral blood of patients with cancer. The enrichment process is extremely important for the isolation of clinically significant CTC subpopulations, which can then be used for further analysis. The present study postulates that the buffer serves as an essential field for immunomagnetic separation, thereby enhancing the efficacy of CTC enrichment in peripheral blood. This, in turn, facilitates CTC detection. Here, we describe the design of buffers for developing a novel immunomagnetic-negative separation method for CTC enrichment. During the design process, the buffer properties of the floating and cell coatings had a synergistic effect on the efficiency of cell enrichment in blood samples. The efficacy of the method was evaluated using peripheral blood samples from patients with non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). The developed method enriched clinically relevant CTC subpopulations that expressed the epithelial-mesenchymal transition (EMT)-related molecule vimentin and/or the cancer immune checkpoint marker programmed death ligand 1 (PD-L1). Furthermore, it was applicable as a part of the enrichment process in a TelomeScan® (OBP-401)-based CTC detection assay with high sensitivity and specificity. From the perspective of methodological approaches, the design of buffer properties can be useful for developing a highly versatile enrichment method for handling CTC heterogeneity.

Fabrication and Characterization of Drug-Loaded Conductive Poly(glycerol sebacate)/Nanoparticle-Based Composite Patch for Myocardial Infarction Applications

Heart tissue engineering is critical in the treatment of myocardial infarction, which may benefit from drug-releasing smart materials. In this study, we load a small molecule (3i-1000) in new biodegradable and conductive patches for application in infarcted myocardium. The composite patches consist of a biocompatible elastomer, poly(glycerol sebacate) (PGS), coupled with collagen type I, used to promote cell attachment. In addition, polypyrrole is incorporated because of its electrical conductivity and to induce cell signaling. Results from the in vitro experiments indicate a high density of cardiac myoblast cells attached on the patches, which stay viable for at least 1 month. The degradation of the patches does not show any cytotoxic effect, while 3i-1000 delivery induces cell proliferation. Conductive patches show high blood wettability and drug release, correlating with the rate of degradation of the PGS matrix. Together with the electrical conductivity and elongation characteristics, the developed biomaterial fits the mechanical, conductive, and biological demands required for cardiac treatment.

Construction of cytokine reservoirs based on sulfated chitosan hydrogels for the capturing of VEGF in situ

Nutrients and oxygen are delivered mainly by blood vessels to nourish the cells and tissues in the body. Thus, biomaterials are processed by loading cytokines, such as vascular endothelial growth factors (VEGF), to facilitate angiogenesis in order to accelerate tissue regeneration. Nevertheless, the unpredictable biosecurity of exogenous cytokines is still a controversial issue for its clinical application. In this study, we constructed a kind of cytokine reservoir utilizing the binding affinity between heparin-like sulfate polysaccharide and endogenous growth factors. Two types of sulfated chitosan hydrogels, namely 6-O-sulfated chitosan (6-O-SCS) and 2-N,6-O-sulfated chitosan (2-N,6-O-SCS) hydrogels, were formed on the surface of the gelatin sponge matrix. The microstructure of the SCS-coated scaffolds is porous and interconnected, which is beneficial for cellular infiltration. Besides, human umbilical vein endothelial cells (HUVECs) can adhere and proliferate well on the surface of the scaffolds. Notably, sulfated chitosan-coated scaffolds exhibit an ability to capture VEGF in vitro & vivo, especially for the 2-N,6-O-SCS-coated scaffold. It is also verified by mice models that sulfated chitosan-coated scaffolds result in a concentrated VEGF microenvironment in specific domains as cytokine reservoirs and induce mass microvessels after implantation into subcutaneous tissues. As such, the sulfated chitosan-coated scaffolds served as VEGF reservoirs to accelerate angiogenesis and wound healing. This beneficial strategy may be applicable to in situ tissue regeneration by capturing more cytokines and promoting healing.

Medical device-induced thrombosis: what causes it and how can we prevent it?

Blood-contacting medical devices, such as vascular grafts, stents, heart valves, and catheters, are often used to treat cardiovascular diseases. Thrombus formation is a common cause of failure of these devices. This study (i) examines the interface between devices and blood, (ii) reviews the pathogenesis of clotting on blood-contacting medical devices, (iii) describes contemporary methods to prevent thrombosis on blood-contacting medical devices, (iv) explains why some anticoagulants are better than others for prevention of thrombosis on medical devices, and (v) identifies future directions in biomaterial research for prevention of thrombosis on blood-contacting medical devices.

The morphology, proliferation rate, and population doubling time factor of adipose-derived mesenchymal stem cells cultured on to non-aqueous SiO2, TiO2, and hybrid sol-gel-derived oxide coatings

In recent years, much attention has been paid to the development of tissue engineering and regenerative medicine, especially when stem cells of various sources are concerned. In addition to the interest in mesenchymal stem cells isolated from bone marrow, recently more consideration has been given to stem cells isolated from adipose tissue (AdMSCs), due to their less invasive method of collection as well as their ease of isolation and culture. However, the development of regenerative medicine requires both the application of biocompatible material and the stem cells to accelerate the regeneration. In this study, we investigated the morphology, proliferation rate index (PRi), and population doubling time factor of adipose-derived mesenchymal stem cells cultured on non-aqueous sol-gel-derived SiO2, TiO2, and SiO2/TiO2 oxide coatings. The results indicated an increase in PRi of AdMSCs when cultured on to titanium dioxide, suggesting its high attractiveness for AdMSCs. In addition, the proper morphology and the shortest doubling time of AdMSCs were observed when cultured on titanium dioxide coating.

Simple method of fabrication of hydrophobic coatings for polyurethanes

The aim of this study was to develop a method of manufacturing versatile hydrophobic coatings for polymers. Authors present a simple technique of polyurethane (PU) surface modification with covalently attached silicones (PDMS) or fluorocarbons (PFC). Diisocyanates were applied as linker molecules. The obtained coatings were characterized using spectroscopic analysis (FTIR), scanning acoustic microscopy (SAM) and water contact angle measurements. FTIR analysis revealed high efficiency of grafting reaction. The results of contact angle measurement indicated significant increase of hydrophobicity — from 66° (unmodified PU) to 113° (PU grafted with PDMS) and 118° (PU grafted with PFC). Acoustic microscopy analysis confirmed satisfactory homogeneity and smoothness of the fabricated layers. In vitro cell tests revealed non-adherent properties of the surfaces. Both, MTT assay and fluorescence staining confirmed non-cytotoxicity of the coatings, which makes them potential candidates for use in biomedical applications.

Synthesis and characterization of polyurethane-block-poly(2-hydroxyethyl methacrylate) hydrogels and their surface modification to promote cell affinity

Physically crosslinked hydrogels based on poly(2-hydroxyethyl methacrylate) (PHEMA) and polyurethane macroiniferter (PUMI) were prepared. The synthesis of polyurethane- block-poly(2-hydroxyethyl methacrylate) (PU-b-PHEMA) was verified by spectroscopic analyses. Due to the low fibronectin adsorption from culture media, cell attachment on PU-b-PHEMA surface was poor compared with the PUMI control. To improve the cell affinity of PU-b-PHEMA, fibronectin was conjugated via surface hydroxyl groups. These biomimetic PU-b-PHEMA hydrogel surfaces were tested for tissue engineering applications. A short-term cell culture study revealed that, compared with the unmodified PU-b-PHEMA, fibronectin-conjugated PU-b-PHEMA hydrogel showed more uniform and dense cell attachment and spreading, indicating a potential use for tissue engineering applications.

Imaging of Membrane Lipids in Single Cells by Imprint-Imaging Time-of-Flight Secondary Ion Mass Spectrometry

A new method for identification and localization of organic molecules in biological samples is described. The method involves making an imprint of a biological sample on a silver (Ag) surface and subsequent analysis of the imprint by imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS). Using this method, detection of unfragmented, Ag cationized molecules at a spatial resolution of <0.5 microm is possible. We have used the method to study the spatial distribution of phosphatidylcholine and cholesterol in blood cells adhering to a glass surface. The TOF-SIMS images show that cholesterol is preferentially located in the plasma membrane, whereas the phosphocholine shows highest concentration in the nuclear membrane. Scanning electron microscopy and fluorescence microscopy images show that the amount of transferred material during the imprinting process can be controlled by varying the imprinting pressure and pretreatment of the cell substrate prior to imprinting.

Platelet adhesion and activation on a shielded plasma gradient prepared on polyethylene

Contact of blood with foreign materials evokes thrombogenic effects to an extent determined partly by the wettability of the biomaterials surface. Tools to study blood response towards a variation in materials wettability with minimal variation in chemistry are "gradient surfaces". However, most gradients have been prepared by diffusion or density immersion techniques, which results in a limited gradient range. Through glow discharge with partial shielding, gradients on polymers were prepared over a length of 5 cm, which facilitated studies to platelet adhesion on separate gradient sections. On polyethylene, advancing water contact angles varied from 90 degrees to 40 degrees, with a hysteresis of 30 degrees. ESCA indicated an increasing incorporation of oxygen towards the hydrophilic end. To examine the role of materials wettability on the activation of adhering platelets, sections of shielded plasma gradients were incubated in anticoagulated whole human blood. Fewer platelets adhered to the hydrophobic end, but those platelets were more activated than those on the hydrophilic end, as judged from their morphology and exposure of GpIIb-IIIa complex. However, partly related to the increased binding of platelets, the clotting activation after platelet deposition was highest on the hydrophilic end. Concluding, this new technique results in a large gradient range, which facilitates studies of formed blood elements in relation to the wettability. Platelets are more activated on hydrophobic polyethylene, while on moderate hydrophilic polyethylene more platelet adhesion and activation of the clotting system occurs.