Topological polymeric glucosyl nanoaggregates in scaffold enable high-density piscine muscle tissue.

Upon the pressure of conventional land agriculture and marine environment facing the future of human beings, the emerging of alternative proteins represented by cultured meat is expected with a breakthrough of efficient, safe and sustainable production. However, the cell proliferation efficiency and final myofiber density in current animal-derived scaffolds are still limited. Here, we incorporated five plant-derived edible polymeric glucosyl nanoparticles (GNPs) into gelatin/alginate hydrogels to spontaneously form nanoaggregates where nanotopographies were observed inside. The nanoscale topological morphology significantly enhances the adhesion and proliferation efficiencies of piscine satellite cells (PSCs) in the tailored extracellular matrix of as-prepared scaffold. Physically, the presence of GNP-induced nanoaggregate increases the interaction between ITG-A1 (membrane protein of PSCs) and hydrogel microenvironment, which activates the focal adhesion-integrin-cytoskeleton mechanotransduction signaling to promote cell proliferation. With a controlled diameter of hydrogel filament, these inner topological GNP nanoaggregates can also improve the density, alignment and differentiation efficiency of PSCs. When cultured in vitro for 15 days, the cell density, size and orientation of muscle fibers in the GNP-stimulated cultured fish fillet are very similar to the total cell mass in native fish muscle tissue.

A comparison of endothelial cell growth on commercial coronary stents with and without laser surface texturing.

Complete endothelialisation of coronary stents is an important determinant of future thrombotic complications following coronary stenting. Stent surface texture is an important factor that influences endothelial cell growth. With the emergence of second and third generation coronary stents, is limited comparative data describing endothelial cell growth in contemporary stent platforms, and limited data available on approaches used to rapidly modify the surfaces of commercial coronary stents to improve endothelialisation. In this study we have determined the in vitro proliferation of the primary human coronary artery endothelial cells on the commonly used 4 types of commercial coronary stents and found that the inner surface of BioMatrix drug-eluting stents (DES), after eliminating of the polymer and drug coating, had significantly higher endothelial cell proliferation compared to that of other bare metal stents (BMS): Multi-Link8, Integrity and Omega. The surfaces of the 3 types of BMS which are smooth, displayed similar endothelial cell proliferation, suggesting the importance of surface features in manipulating endothelial cell growth. Laser surface texturing was used to create micro/nano patterns on the stents. The laser treatment has significantly increased endothelial proliferation on the inner surfaces of all 4 types of stents, and Multi-Link8 stents displayed the highest (>100%) improvement. The laser textured BioMatrix stents had the highest absolute number of endothelial cells growth. Our results provided useful information in the endothelialisation potential for the commonly used commercial coronary stents and suggested a potential future application of laser surface bioengineering to coronary stents for better biocompatibility of the device.

Polyhydroxybutyrate (PHB) in nanoparticulate form improves physical and biological performance of scaffolds.

Polyhydroxyalkanoates (PHAs) are natural polyesters produced by microorganisms as a source of intracellular energy reserves. Due to their desirable material characteristics, these polymers have been thoroughly investigated for tissue engineering and drug delivery applications. A tissue engineering scaffold serves as a substitute of the native extracellular matrix (ECM) and plays a crucial role in tissue regeneration by providing temporary support for cells during natural ECM formation. In this study, porous, biodegradable scaffolds were prepared using native polyhydroxybutyrate (PHB) and PHB in nanoparticulate form using salt leaching method, to investigate the differences in the physicochemical properties such as crystallinity, hydrophobicity, surface morphology, roughness, and surface area and biological properties of the prepared scaffolds. As per the BET analysis, PHB nanoparticles-based (PHBN) scaffolds presented a significant difference in the surface area as compare to PHB scaffolds. PHBN scaffolds showed decreased crystallinity and improved mechanical strength as compared to PHB scaffolds. Thermogravimetry analysis shows delayed degradation of PHBN scaffolds. An examination of Vero cell lines' cell viability and adhesion over time revealed enhanced performance of PHBN scaffolds. Our research suggests that scaffold made of PHB nanoparticles could serve as a superior material for tissue engineering applications than its native form.

Superhydrophilic and topography-regulatable surface grafting on PEEK to improve cellular affinity.

Polyetheretherketone (PEEK) has been widely used in the preparation of orthopedic implants due to its biological inertness and similar mechanical modulus to natural bone. However, the affinity between biological tissue (bone and soft tissue) and PEEK surface is weak, leading to low osseointegration and an increased risk of inflammation. The situation could be improved by modifying PEEK surface. Surfaces with good hydrophilicity and proper microtopography would promote cellular adhesion and proliferation. This work presented a two-step surface modification method to achieve the effect. Polyacrylic acid (PAA) chains were grafted on PEEK surface by UV irradiation. Then, ethylenediamine (EDA) was added to introduce amino groups and promote the cross-linking of PAA chains. Furthermore, a mathematical model was built to describe and regulate the surface topography growth process semi-quantitatively. The model fits experimental data quite well (adjusted R2 = 0.779). Results showed that the modified PEEK surface obtained superhydrophilicity. It significantly improved the adhesion and proliferation of BMSCs and MFBs by activating the FAK pathway and Rho family GTPase. The cellular affinity performed better when the surface topography was in network structure with holes in about 25 µm depth and 20-50 µm diameter. Good hydrophilicity seems necessary for the FAK pathway activation, but simply improving surface hydrophilicity might not be enough for cellular affinity improvement. Surface topography at micron scale should be a more important cue. This simple surface modification method could be contributed to further study of cell-microtopography interaction and have potential applications in clinical PEEK orthopedic implants.

Fabricated polyhydroxyalkanoates blend scaffolds enhance cell viability and cell proliferation.

For tissue engineering applications, cell adhesion and proliferation are crucial factors, and blending polymers is one of the most effective ways to create a biocompatible scaffold with desired properties. In order to create new potential porous, biodegradable scaffolds using salt leaching technique, poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were blended in different ratios. SEM, BET, FTIR, and water contact angle measurements were used to analyze the scaffolds' porous surface, surface area, and roughness, chemical interaction, and hydrophilicity. Additionally, a hemolysis assay revealed that the mixtures were hemocompatible and had no impact on red blood cells. Different cells- Vero, Hela and MDBK cell lines cultured on the porous mats of these biopolymeric scaffolds exhibited significant increase in cell viability and attachment over time. The overall finding was that blended scaffolds exhibited reduced crystallinity, diverse porosity, higher surface area and hydrophilicity, and better cell viability, proliferation and adhesion. Our findings imply that a blended scaffold could be more suitable for use in tissue engineering applications.

Effects of Titanium Implant Surface Topology on Bone Cell Attachment and Proliferation in vitro.

Purpose: Titanium is commonly used for implants because of its corrosion resistance and osseointegration capability. It is well known that surface topology affects the response of bone tissue towards implants. In vivo studies have shown that in weeks or months, bone tissue bonds more efficiently to titanium implants with rough surfaces compared to smooth surfaces. In addition, stimulating early endosseous integration increases the long-term stability of bone-implants and hence their clinical outcome. Here, we evaluated the response of human MG-63 osteoblast-like cells to flat and solid, compared to rough and porous surface topologies in vitro 1-6 days post seeding. We compared the morphology, proliferation, and attachment of cells onto three smooth surfaces: tissue culture (TC) plastic or microscope cover glasses, machined polyether-ether-ketone (PEEK), and machined solid titanium, to cells on a highly porous (average Ra 22.94 µm) plasma-sprayed titanium surface (composite Ti-PEEK spine implants). Methods: We used immuno-fluorescence (IF) and scanning electron microscopy (SEM), as well as Live/Dead and WST-1 cell proliferation assays. Results: SEM analyses confirmed the rough topology of the titanium implant surface, compared to the smooth surface of PEEK, solid titanium, TC plastic and cover glasses. In addition, SEM analyses revealed that MG-63 cells seeded onto smooth surfaces (solid titanium, PEEK) adopted a flat, planar morphology, while cells on the rough titanium surface adopted an elongated morphology with numerous filopodial and lamellipodial extensions interacting with the substrate. Finally, IF analyses of focal adhesions (vinculin, focal adhesion kinase), as well as proliferation assays indicate that MG-63 cells adhere less and proliferate at a slower rate on the rough than on a smooth titanium surface. Conclusion: These observations suggest that bone-forming osteoblasts adhere less strongly and proliferate slower on rough compared to smooth titanium surfaces, likely promoting cell differentiation, which is in agreement with other porous implant materials.

Simple ultrasonic-assisted approach to prepare polysaccharide-based aerogel for cell research and histocompatibility study.

Salecan, a water-soluble microbial polysaccharide with attractive biocompatible characteristics, is very suitable for aerogel fabrication. However, the practical application of salecan-based aerogels for cell culture was limited by complicated preparation method, lack of cell anchorage signals, and the ability to modulate this properly. Here, a smart aerogel was designed by ultrasonic-assisted self-assembly of salecan and cationic starch (CAS) without any organic and toxic crosslinkers. The ultrasound waves generated a marked impact on self-assemble process by means of ultrasonic cavitation. Aerogel network was produced by strong electrostatic attractions between the polysaccharides. Especially, salecan/CAS ratio can be precisely modulated to tailor the hydrophilicity, mechanical stiffness, and morphologic property. The specific surface area of the aerogels gradually increased with the increase in salecan/CAS ratio. These aerogels were non-cytotoxic, and the incorporation of salecan into them promoted cell-matrix interactions by directionally supporting cell adhesion and proliferation. Most strikingly, in vivo experiment revealed that the histological features in the main organs of the mice were similar to those observed in the PBS-treated control group, and no sign of the histopathological abnormality or tissue destruction was observed, indicating the excellent histocompatibility of the aerogels. This study offered a new and powerful avenue to fabricate functional biomaterial.

Porous Zirconia/Magnesia Ceramics Support Osteogenic Potential In Vitro.

Porous zirconia (ZrO2), magnesia (MgO) and zirconia/magnesia (ZrO2/MgO) ceramics were synthesised by sintering and designated as ZrO2(100), ZrO2(75)MgO(25), ZrO2(50)MgO(50), ZrO2(25)MgO(75), MgO(100) based on their composition. The ceramic samples were characterised by means of scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and atomic absorption spectrometry to explore the incorporation of Mg atoms into the zirconia lattice. The resulting porosity of the samples was calculated based on the composition and density. The final porosity of the cylinder-shaped ceramic samples ranged between 30 and 37%. The mechanical analysis exhibited that the Young modulus increased and the microstress decreased with increasing magnesia amount, with values ranging from 175 GPa for zirconia to 301 GPa for magnesia. The adhesion, viability, proliferation and osteogenic activity of MC3T3-E1 pre-osteoblastic cells cultured on the zirconia/magnesia ceramics was found to increase, with the magnesia-containing ceramics exhibiting higher values of calcium mineralisation. The results from the mechanical analysis, the ALP activity, the calcium and collagen production demonstrate that the zirconia/magnesia ceramics possess robust osteoinductive capacity, therefore holding great potential for bone tissue engineering.

Nano-micrometer surface roughness gradients reveal topographical influences on differentiating responses of vascular cells on biodegradable magnesium.

Distinctively directing endothelial cells (ECs) and smooth muscle cells (SMCs), potentially by surface topography cue, is of central importance for enhancing bioefficacy of vascular implants. For the first time, surface gradients with a broad range of nano-micrometer roughness are developed on Mg, a promising next-generation biodegradable metal, to carry out a systematic study on the response of ECs and SMCs. Cell adhesion, spreading, and proliferation are quantified along gradients by high-throughput imaging, illustrating drastic divergence between ECs and SMCs, especially in highly rough regions. The profound role of surface topography overcoming the biochemical cue of released Mg2+ is unraveled at different roughness ranges for ECs and SMCs. Further insights into the underlying regulatory mechanism are gained at subcellular and gene levels. Our work enables high-efficient exploration of optimized surface morphology for modulating favored cell selectivity of promoting ECs and suppressing SMCs, providing a potential strategy to achieve rapid endothelialization for Mg.

Distribution of the Degree of Deacetylation of Surface-Deacetylated Chitin Nanofibers: Effects on Crystalline Structure and Cell Adhesion and Proliferation.

The degree of deacetylation (DD) of chitinous nanofibers (NFs) has been shown to significantly influence their bioactivity. However, the relationship between the cell affinity of NFs and the detailed structural features within NFs remains unclear and provides the focus of this study. Commercially available chitin nanofiber (ChNF) was deacetylated by high-concentration alkaline treatment in the nanofibrous state. For the ChNF and its deacetylated product (dChNF), it was possible to determine the overall DD as well as its distribution by 1H NMR in a series of LiOD/urea-d4/D2O solvents. In particular, the surface-to-internal DD distribution of the chitinous NFs was evaluated for the first time to the knowledge of the authors. Wide-angle X-ray diffraction showed that the crystallinity associated with hydrophilicity/hydrophobicity was altered by the DD. Mouse fibroblast L929 adhesion tests indicated that the surface and internal structures of dChNF contributed to an increase in cell adhesion initially and proliferation after the extended culture time, respectively. The comprehensive mechanistic data obtained will allow the potential of chitinous NFs to be maximized for biomedical applications.

Electrospun biodegradable chitosan based-poly(urethane urea) scaffolds for soft tissue engineering.

The composition and architecture of a scaffold determine its supportive role in tissue regeneration. In this work, we demonstrate the feasibility of obtaining a porous electrospun fibrous structure from biodegradable polyurethanes (Pus) synthesized using polycaprolactone-diol as soft segment and, as chain extenders, chitosan (CS) and/or dimethylol propionic acid. Fourier transform infrared spectroscopy and proton nuclear magnetic resonance confirmed the syntheses. Fibre mats' properties were analysed and compared with those of solvent cast films. Scanning electron microscopy images of the electrospun scaffolds revealed fibres with diameters around 1 µm. From tensile tests, we found that Young's modulus increases with CS content and is higher for films (2.5 MPa to 6.5 MPa) than for the corresponding fibre mats (0.8 MPa to 3.2 MPa). The use of CS as the only chain extender improves recovery ratio and resilience. From X-ray diffraction, a higher crystalline degree was identified in fibre mats than in the corresponding films. Films' wettability was enhanced by the presence of CS as shown by the decrease of water contact angle. X-ray photoelectron spectroscopy revealed that while ester groups are predominant at the films' surface, ester and urethanes are present in similar concentrations at fibres' surface, favouring the interaction with water molecules. Both films and fibres undergo hydrolytic degradation. In vitro evaluation was performed with human dermal fibroblasts. No PU sample revealed cytotoxicity. Cells adhered to fibre mats better than to films and proliferation was observed only for samples of CS-containing PUs. Results suggest that electrospun fibres of CS-based polyurethanes are good candidate scaffolds for soft tissue engineering.

Effects of Zn and Ag Ratio on Cell Adhesion and Antibacterial Properties of Zn/Ag Coimplanted TiN.

Titanium alloy (Ti-6Al-4 V) has good biocompatibility and mechanical properties, but its biologically inert and poor antibacterial property limit its application in the field of medical implants. In this study, titanium nitride (TiN) is first deposited on the surface of titanium alloy to wrap toxic elements (for example, vanadium). Then Zn and Ag ions with different ratios are simultaneously implanted into TiN via a plasma immersion ion implantation (PIII) system. X-ray photoelectron spectrometer proves the presence of Zn, Ag, and TiN on the surface of Zn/Ag-TiN. Protein adsorption suggests that, with the increase of Zn ratio, the adsorption ability is enhanced. Biological assays indicate that Zn/Ag(1/0.3)-TiN has the best cell proliferation and adhesion, because it has a larger ratio of Zn. Zn/Ag(1/2)-TiN has the best antibacterial effect and followed by Zn/Ag(1/0.3)-TiN, since Ag plays a major role in antibacterial activity and Zn is auxiliary. But a large ratio of Ag not only impairs cells but also has a negative effect on antibacterial activity. In conclusion, Zn/Ag(1/0.3)-TiN offers both excellent cytocompatibility and antibacterial activity and has great potential in orthopedic implants.

Design of a novel polysaccharide-based cryogel using triallyl cyanurate as crosslinker for cell adhesion and proliferation.

Salecan, a water-soluble extracellular ß-glucan, is considered as an attractive alternative for hydrogel preparation due to its good physicochemical and biological properties. Herein, a novel cryogel was prepared by cryopolymerization of salecan and acryloyloxyethyltrimethyl ammonium chloride using triallyl cyanurate (TAC) as a crosslinker. FT-IR spectroscopy and XRD analysis confirmed the structure of cryogels. The addition of more hydrophilic salecan inside the cryogels significantly increased their water uptake. More importantly, the compressive and storage moduli were significantly improved by the introduction of TAC as crosslinker, probably due to the multiplication of potential crosslinking points when TAC was used in the polymerization process and subsequent the formation of a stiffer polymer network. In vitro cytotoxicity assay confirmed the non-cytotoxic nature of the cryogels. They were biocompatible and supported adhesion, proliferation and viability of L929 and 3 T3-L1 cells as shown by cell proliferation and Live/Dead assay. Altogether, this work opens a door to the design and development of mechanically strong salecan-based cryogel for cell adhesion and proliferation, and further soft tissue engineering application.

Tailoring Polyelectrolyte Architecture To Promote Cell Growth and Inhibit Bacterial Adhesion.

An important challenge facing the application of implanted biomaterials for tissue engineering is the need to facilitate desirable tissue interactions with the implant while simultaneously inhibiting bacterial colonization, which can lead to implant-associated infection. In this study, we explore the relevance of the physical parameters of polyelectrolyte multilayers, such as surface charge, wettability, and stiffness, in tissue cell/surface and bacteria/surface interactions, and investigate the tuning of the multilayer architecture to differentially control such interactions. Polyions with different side-chain chemical structures were paired with polyethylenimine to assemble multilayers with parallel control over surface charge and wettability under controlled conditions. The multilayers can be successfully cross-linked to yield stiffer (the apparent Young's modulus was increased more than three times its original value) and more stable films while maintaining parallel control over surface charge and wettability. The initial adhesion and proliferation of 3T3 fibroblast cells were found to be strongly affected by surface charge and wettability on the non-cross-linked multilayers. On the other hand, these cells adhered and proliferated in a manner similar to those on the cross-linked multilayers (apparent Young's modulus ∼2 MPa), regardless of surface charge and wettability. In contrast, Staphylococcus aureus ( S. aureus) and Escherichia coli ( E. coli) adhesion was primarily controlled by surface charge and wettability on both cross-linked and non-cross-linked multilayers. In both cases, negative charge and hydrophilicity inhibited their adhesion. Thus, a surface coating with a relatively high degree of stiffness from covalent cross-linking coupled with negative surface charge and high wettability can serve as an efficient strategy to enhance host cell growth while resisting bacterial colonization.

Synergistic Effect of Cold Plasma Treatment and RGD Peptide Coating on Cell Proliferation over Titanium Surfaces.

The aim of this study was to investigate the synergistic effect of cold atmospheric plasma (CAP) treatment and RGD peptide coating for enhancing cellular attachment and proliferation over titanium (Ti) surfaces. The surface structure of CAP-treated and RGD peptide-coated Ti discs were characterized by contact angle goniometer and atomic force microscopy. The effect of such surface modification on human bone marrow derived mesenchymal stem cells (hMSCs) adhesion and proliferation was assessed by cell proliferation and DNA content assays. Besides, hMSCs' adhesion and morphology on surface modified Ti discs were observed via fluorescent and scanning electron microscopy. RGD peptide coating following CAP treatment significantly enhanced cellular adhesion and proliferation among untreated, CAP-treated and RGD peptide-coated Ti discs. The treatment of Ti surfaces with CAP may contribute to improved RGD peptide coating, which enables increased cellular integrations with the Ti surfaces.

Mitigated reactive oxygen species generation leads to an improvement of cell proliferation on poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] functionalized polydimethylsiloxane surfaces.

In vitro cell-based analysis is strongly affected by material's surface chemical properties. The cell spreading, migration, and proliferation on a substrate surface are initiated and controlled by successful adhesion, particularly for anchor-dependent cells. Unfortunately, polydimethylsiloxane (PDMS), one of the most used polymeric materials for construction of microfluidic and miniaturized biomedical analytic devices, is not a cell-friendly surface because of its inherent hydrophobic property. Herein, a poly[glycidyl methacrylate-co-poly(ethylene glycol) methacrylate] (poly(GMA-co-pEGMA)) polymer brush was synthesized on a PDMS surface through a surface-initiated atom-transfer radical polymerization method. Contact angle and Fourier transform infrared characterization show that the poly (GMA-co-pEGMA) polymer brush functionalization can increase wettability of PDMS and introduce epoxy, hydroxyl, and ether groups into PDMS surface. In vitro cell growth assay demonstrates that cell adhesion and proliferation on poly(GMA-co-pEGMA) polymer brush-functionalized PDMS (poly(GMA-co-pEGMA)@PDMS) are better than on pristine PDMS. Additionally, immobilization of collagen type I (CI) and fibronectin (FN) on poly(GMA-co-pEGMA)@PDMS is better than direct coating of CI and FN on pristine PDMS to promote cell adhesion. Furthermore, increased intracellular reactive oxygen species and cell mitochondrial membrane depolarization, two indicators of cell oxidative stress, are observed from cells growing on pristine PDMS, but not from those on poly(GMA-co-pEGMA)@PDMS. Collectively, we demonstrate that poly(GMA-co-pEGMA) functionalization can enhance cell adhesion and proliferation on PDMS, and thus can be potentially used for microfluidic cell assay devices for cellular physiology study or drug screening.

Adhesion and growth of human bone marrow mesenchymal stem cells on precise-geometry 3D organic-inorganic composite scaffolds for bone repair.

Engineering biomaterial scaffolds that promote attachment and growth of mesenchymal stem cells in three dimensions is a crucial parameter for successful bone tissue engineering. Towards this direction, a lot of research effort has focused recently into the development of three-dimensional porous scaffolds, aiming to elicit positive cellular behavior. However, the fabrication of three-dimensional tissue scaffolds with a precise geometry and complex micro- and nano-features, supporting cell in-growth remains a challenge. In this study we report on a positive cellular response of human bone marrow-derived (BM) mesenchymal stem cells (MSCs) onto hybrid material scaffolds consisting of methacryloxypropyl trimethoxysilane, zirconium propoxide, and 2-(dimethylamino)ethyl methacrylate (DMAEMA). First, we use Direct fs Laser Writing, a 3D scaffolding technology to fabricate the complex structures. Subsequently, we investigate the morphology, viability and proliferation of BM-MSCs onto the hybrid scaffolds and examine the cellular response from different donors. Finally, we explore the effect of the materials' chemical composition on cell proliferation, employing three different material surfaces: (i) a hybrid consisting of methacryloxypropyl trimethoxysilane, zirconium propoxide and 50mol% DMAEMA, (ii) a hybrid material comprising methacryloxypropyl trimethoxysilane and zirconium propoxide, and (iii) a purely organic polyDMAEMA. Our results show a strong adhesion of BM-MSCs onto the hybrid material containing 50% DMAEMA from the first 2h after seeding, and up to several days, and a proliferation increase after 14 and 21days, similar to the polystyrene control, independent of cell donor. These findings support the potential use of our proposed cell-material combination in bone tissue engineering.

Dose-dependent surface endothelialization and biocompatibility of polyurethane noble metal nanocomposites.

Surface pre-endothelialization is a promising approach to improve the hemocompatibility of implants, medical devices, and artificial organs. To promote the adhesive property of thermoplastic polyurethane (TPU) for endothelial cells (ECs), up to 1 wt % of gold (Au) or platinum (Pt) nanoparticles, fabricated by pulsed laser ablation in polymer solution, were embedded into the polymer matrix. The analysis of these nanocomposites showed a homogenous dispersion of the nanoparticles, with average diameters of 7 nm for Au or 9 nm for Pt. A dose-dependent effect was found when ECs were seeded onto nanocomposites comprising different nanoparticle concentrations, resulting in a fivefold improvement of proliferation at 0.1 wt % nanoparticle load. This effect was associated with a nanoparticle concentration-dependent hydrophilicity and negative charge of the nanocomposite. In dynamic flow tests, nanocomposites containing 0.1 wt % Au or Pt nanoparticles allowed for the generation of a confluent and resistant EC layer. Real-time polymerase chain reaction quantification of specific markers for EC activation indicated that ECs cultivated on nanocomposites remain in an inactivated, nonthrombogenic and noninflammatory state; however, maintain the ability to trigger an inflammatory response upon stimulation. These findings were confirmed by a platelet and leukocyte adhesion assay. The results of this study suggest the possible applicability of TPU nanocomposites, containing 0.1 wt % Au or Pt nanoparticles, for the generation of pre-endothelialized surfaces of medical devices.

Enhancement of endothelialisation of coronary stents by laser surface engineering.

BACKGROUND AND OBJECTIVE: Coronary stents have been widely used in the treatment of coronary heart disease. However, complications have hampered the long-term success of the device. Bare-metal stents (BMS) have a high rate of restenosis and poor endothelialisation. The drug-eluting stents (DES), although dramatically reduce restenosis, significantly prevent endothelialisation leading to late thrombosis and behave the same way as BMS after drug releasing. Rapid adhesion and growth of endothelial cells on the stent surface is a key process for early vascular healing after coronary stenting which contributes to the reduction of major complications. Surface properties manipulate cell growth and directly determine the success and life-span of the implants. However, the ideal surface properties of coronary stents are not yet fully understood. The objective of this research is to understand how surface micro/nano textures and associated material chemistry changes generated by a laser beam affect the behavior of endothelial cells on bare metal 316L stents. MATERIALS AND METHODS: A high power laser beam was applied to modifying the surface properties of 316L coronary stent material and the commercial coronary stents, followed by examination of the adhesion and proliferation of human coronary endothelial cells that were growing on the surfaces. Surface properties were examined by scanning electron microscopy, contact angle measurement, and X-ray photoelectron spectroscopy. RESULTS: A novel surface with combined micro/nano features was created on stent material 316L and coronary stent with a specific surface chemistry. This surface gives rise to a threefold increase in the adhesion and eightfold increase in the proliferation of endothelial cells. Interestingly, such effects were only observed when the surface texture was produced in the nitrogen atmosphere suggesting the importance of the surface chemistry, including the dramatic increase of chromium nitride, for the interaction of endothelial cells with the material surface. This novel surface is also super-hydrophilic with close to zero water/cell culture fluid contact angles and low cytotoxicity. CONCLUSIONS: A novel surface created by laser surface-engineering with a combination of defined surface texture and surface chemistry was found beneficial for the improvement of coronary stent endothelialisation. The technology presented here could work with both DES and BMS with added benefit for the improvement of the biocompatibility of current coronary stents.