γ-Cyclodextrin hydrogel for the sustained release of josamycin for potential ocular application.

Glaucoma is the leading cause of blindness worldwide. However, its surgical treatment, in particular via trabeculectomy, can be complicated by fibrosis. In current clinical practice, application of the drug, Mitomycin C, prevents or delays fibrosis, but can lead to additional side effects, such as bleb leakage and hypotony. Previous in silico drug screening and in vitro testing has identified the known antibiotic, josamycin, as a possible alternative antifibrotic medication with potentially fewer side effects. However, a suitable ocular delivery mechanism for the hydrophobic drug to the surgical site does not yet exist. Therefore, the focus of this paper is the development of an implantable drug delivery system for sustained delivery of josamycin after glaucoma surgery based on crosslinked γ-cyclodextrin. γ-Cyclodextrin is a commonly used solubilizer which was shown to complex with josamycin, drastically increasing the drug's solubility in aqueous solutions. A simple γ-cyclodextrin crosslinking method produced biocompatible hydrogels well-suited for implantation. The crosslinked γ - cyclodextrin retained the ability to form complexes with josamycin, resulting in a 4-fold higher drug loading efficiency when compared to linear dextran hydrogels, and prolonged drug release over 4 days.

Fetuin A functionalisation of biodegradable PLLA-co-PEG nonwovens towards enhanced biomineralisation and osteoblastic growth behaviour.

Therapy for large-scale bone defects remains a major challenge in regenerative medicine. In this context, biodegradable electrospun nonwovens are a promising material to be applied as a temporary implantable scaffold as their fibre diameters are in the micro- and nanometre range and possess a high surface-to-volume ratio paired with high porosity. In this work, in vitro assessment of biodegradable PLLA-co-PEG nonwovens with fetuin A covalently anchored to the surface has been performed in terms of biomineralisation and the influence on MG-63 osteoblast cell metabolic activity, biosynthesis of type I collagen propeptide and inflammatory potential. Our finding was that covalent fetuin A funtionalisation of the nonwoven material leads to a distinct increase in calcium affinity, thus enhancing biomineralisation while maintaining the distinct fibre morphology of the nonwoven. The cell seeding experiments showed that the fetuin A functionalised and subsequently in vitro biomineralised PLLA-co-PEG nonwovens did not show negative effects on MG-63 growth. Fetuin A funtionalisation and enhanced biomineralisation supported cell attachment, leading to improved cell morphology, spreading and infiltration into the material. Furthermore, no signs of increase in the inflammatory potential of the material have been detected by flow cytometry experiments. Overall, this study provides a contribution towards the development of artificial scaffolds for guided bone regeneration with the potential to enhance osteoinduction and osteogenesis.

Accelerated Endothelialization of Nanofibrous Scaffolds for Biomimetic Cardiovascular Implants.

Nanofiber nonwovens are highly promising to serve as biomimetic scaffolds for pioneering cardiac implants such as drug-eluting stent systems or heart valve prosthetics. For successful implant integration, rapid and homogeneous endothelialization is of utmost importance as it forms a hemocompatible surface. This study aims at physicochemical and biological evaluation of various electrospun polymer scaffolds, made of FDA approved medical-grade plastics. Human endothelial cells (EA.hy926) were examined for cell attachment, morphology, viability, as well as actin and PECAM 1 expression. The appraisal of the untreated poly-L-lactide (PLLA L210), poly-ε-caprolactone (PCL) and polyamide-6 (PA-6) nonwovens shows that the hydrophilicity (water contact angle > 80°) and surface free energy (<60 mN/m) is mostly insufficient for rapid cell colonization. Therefore, modification of the surface tension of nonpolar polymer scaffolds by plasma energy was initiated, leading to more than 60% increased wettability and improved colonization. Additionally, NH3-plasma surface functionalization resulted in a more physiological localization of cell−cell contact markers, promoting endothelialization on all polymeric surfaces, while fiber diameter remained unaltered. Our data indicates that hydrophobic nonwovens are often insufficient to mimic the native extracellular matrix but also that they can be easily adapted by targeted post-processing steps such as plasma treatment. The results achieved increase the understanding of cell−implant interactions of nanostructured polymer-based biomaterial surfaces in blood contact while also advocating for plasma technology to increase the surface energy of nonpolar biostable, as well as biodegradable polymer scaffolds. Thus, we highlight the potential of plasma-activated electrospun polymer scaffolds for the development of advanced cardiac implants.

Effect of Collagen Nanofibers and Silanization on the Interaction of HaCaT Keratinocytes and 3T3 Fibroblasts with Alumina Nanopores.

During wound healing, a complex cascade of cellular and molecular events occurs, which is governed by topographical and biochemical cues. Therefore, optimal tissue repair requires scaffold materials with versatile structural and biochemical features. Nanoporous anodic aluminum oxide (AAO) membranes exhibit good biocompatibility along with customizable nanotopography and antimicrobial properties, which has brought them into the focus of wound treatment. However, despite their good permeability, such bioinert ceramic nanopores cannot actively promote cell growth as they lack biochemical cues to support specific ligand-receptor interactions. Therefore, we modified AAO nanopores with the biochemical features of collagen nanofibers or amino groups provided by silanization with (3-aminopropyl)triethoxysilane (APTES) to design a permeable scaffold material that can additionally promote cell adhesion. Viability assays revealed that the metabolic activity of both 3T3 fibroblasts and HaCaT keratinocytes on bare and silanized AAO pores was comparable to glass controls until 72 h. Interestingly, both cell types showed a reduced proliferation on AAO with collagen nanofibers. Nevertheless, scanning electron and fluorescence microscopy revealed that 3T3 fibroblasts exhibited a well-spread morphology with filopodia attached to the nanoporous surface of the underlying AAO membranes or nanofibrous collagen networks, thus indicating a close interaction with the composites. Keratinocytes, although growing in clusters on bare and APTES-modified AAO, also adhered well on collagen-modified AAO membranes. When in contact with Escherichia coli suspensions for 20 h, the AAO membranes successfully prevented bacteria penetration irrespective of the biochemical functionalization. In summary, both functionalization strategies have high potential to specifically control molecular signaling and cell migration to further develop alumina nanopores for wound healing.

Comparison of different cell culture plates for the enrichment of non-adherent human mononuclear cells.

While tissue-resident monocytes and macrophages are considered to be vital players in the in vivo interaction between biomaterials and surrounding tissue, their isolation is limited. In order to establish in vitro models elucidating implant and tissue interactions, peripheral blood mononuclear cells (PBMCs) represent a viable source for bone marrow-derived monocytes and an alternative to tissue-resident cells. The aim of present study was to analyse different adhesion-preventing tissue culture plates for their potential to facilitate the culture of monocytes without differentiation into macrophages. Freshly isolated PBMCs were seeded into four commercially available tissue culture plates with different adhesive properties and were tested for surface CD14 and CD68 expression using flow cytometry following 7 days in culture. When PBMCs were cultivated in RPMI on Cellstar® Cell culture plates with Cell-Repellent Surface, a significant increase in CD14-positive cells was observed compared with cultivation in standard tissue culture-treated plates. This was accompanied by elevated cytokine production of interleukin-6 (IL6) and interleukin-8 (IL8); however, overall cell growth was not affected. When PBMCs were pre-cultured in cell-repellent plates, there was a higher yield of adherent cells after subsequent transfer into standard tissue culture-treated plates. Cultivation of PBMCs on cell-repellent culture plates favoured a monocytic phenotype and thus, represents an alternative to increase the fraction of monocytes yielded from PBMCs.

Influence of analyzed lubricant volumes on the amount and characteristics of generated wear particles from three different types of polyethylene liner materials.

The articulating components of artificial joints consist mainly of metals, ceramics, or polymers. Resulting abrasive wear particles can promote osteolysis and aseptic loosening of the endo-prosthetic implants. Ultra-high-molecular-weight-polyethylene is the material used most for bearing couples in total hip replacement. In the present study, three types of polyethylene (PE) liners varying in material composition, i.e., (1) conventional PE (C-PE), (2) sequentially cross-linked PE (SX-PE), (3) cross-linked PE blended with vitamin E (EX-PE) articulating with two types of femoral heads were used. After ultrasound treatment of each simulator lubricant, different concentrations (0.1/0.25/0.5/1.0 mL) were taken and dissolved in hydrochloric acid (37%) in a similar manner. The aim was to analyze the characteristics of wear particles generated in a hip simulator, with respect to different volumes of the lubricant. Within the scope of particle analysis, distinct alterations for particle characteristics were determined in the lubricant volumes and types of PE material used. A significant decrease in particle number for SX-PE liners, compared to the C-PE inserts and even more for EX-PE inserts, was detected at each lubricant volume. Particle morphologies varied depending on PE material. Alterations in particle size and other morphologic parameters between the four tested volumes, could be proven for each PE type. In general, particle sizes and parameters (e.g., length and width) increased with increasing serum volumes. In conclusion, the chosen volume of the simulator lubricant used for particle analysis has a crucial influence on detected particle number, size distribution, and morphologic parameters. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1299-1306, 2018.

Biocompatibility and Inflammatory Potential of Titanium Alloys Cultivated with Human Osteoblasts, Fibroblasts and Macrophages.

The biomaterials used to maintain or replace functions in the human body consist mainly of metals, ceramics or polymers. In orthopedic surgery, metallic materials, especially titanium and its alloys, are the most common, due to their excellent mechanical properties, corrosion resistance, and biocompatibility. Aside from the established Ti6Al4V alloy, shape memory materials such as nickel-titanium (NiTi) have risen in importance, but are also discussed because of the adverse effects of nickel ions. These might be reduced by specific surface modifications. In the present in vitro study, the osteoblastic cell line MG-63 as well as primary human osteoblasts, fibroblasts, and macrophages were cultured on titanium alloys (forged Ti6Al4V, additive manufactured Ti6Al4V, NiTi, and Diamond-Like-Carbon (DLC)-coated NiTi) to verify their specific biocompatibility and inflammatory potential. Additive manufactured Ti6Al4V and NiTi revealed the highest levels of metabolic cell activity. DLC-coated NiTi appeared as a suitable surface for cell growth, showing the highest collagen production. None of the implant materials caused a strong inflammatory response. In general, no distinct cell-specific response could be observed for the materials and surface coating used. In summary, all tested titanium alloys seem to be biologically appropriate for application in orthopedic surgery.

Direct influence of titanium and zirconia particles on the morphology and functionality of mature human osteoclasts.

Within the last ten years of biomedical implants, the focus is increasingly on bioceramics, specifically on zirconia (ZrO2 ). Hence, we analyzed the impact of ZrO2 particles in comparison to titanium particles on mature human osteoclasts (OCs) as little is known about the direct effect of wear particles on mature OCs and their role in the osteolytic process during aseptic endoprosthesis loosening. Changes in cell morphology and functionality of OCs incubated with particles in different concentrations were investigated in vitro. OCs tend to be enlarged after three days of cultivation with both types of particles, especially with high concentrations of ZrO2 , suggesting increased cell fusion. Further, we identified significantly increased expression of OC specific and bone matrix related genes: VNR, RANK, TRAP, and CTSK pointing on a direct stimulatory particle effect on the functionality of mature OCs. In completion, we quantified the bone resorption activity of particle treated mature OCs but could not detect a significant difference in bone resorption compared to OCs cultivated without particles. However, we could identify significantly higher gene expression of MMP-1 in particle treated OCs compared to untreated control OCs after three days of incubation. We also detected an impaired production of the tissue inhibitor of metalloproteinase, especially for OCs treated with high ZrO2 concentrations. In conclusion, our in vitro data show that abrasion particles could have a direct influence on mature OCs and therefore could promote increased OC-mediated bone resorption during aseptic loosening of total joint replacements. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2608-2615, 2017.

Influence of different grained powders and pellets made of Niobium and Ti-42Nb on human cell viability.

Nowadays, biomaterials can be used to maintain or replace several functions of the human body if necessary. Titanium and its alloys, i.e. Ti6Al4V are the most common materials (70 to 80%) used for structural orthopedic implants due to their unique combination of good mechanical properties, corrosion resistance and biocompatibility. Addition of ß-stabilizers, e.g. niobium, can improve the mechanical properties of such titanium alloys further, simultaneously offering excellent biocompatibility. In this in vitro study, human osteoblasts and fibroblasts were cultured on different niobium specimens (Nb Amperit, Nb Ampertec), Nb sheets and Ti-42Nb (sintered and 3D-printed by selective laser melting, SLM) and compared with forged Ti6Al4V specimens. Furthermore, human osteoblasts were incubated with particulates of the Nb and Ti-42Nb specimens in three concentrations over four and seven days to imitate influence of wear debris. Thereby, the specimens with the roughest surfaces, i.e. Ti-42Nb and Nb Ampertec, revealed excellent and similar results for both cell types concerning cell viability and collagen synthesis superior to forged Ti6Al4V. Examinations with particulate debris disclosed a dose-dependent influence of all powders with Nb Ampertec showing the highest decrease of cell viability and collagen synthesis. Furthermore, interleukin synthesis was only slightly increased for all powders. In summary, Nb Ampertec (sintered Nb) and Ti-42Nb materials seem to be promising alternatives for medical applications compared to common materials like forged or melted Ti6Al4V.

Influence of Different Three-Dimensional Open Porous Titanium Scaffold Designs on Human Osteoblasts Behavior in Static and Dynamic Cell Investigations.

In the treatment of osseous defects micro-structured three-dimensional materials for bone replacement serve as leading structure for cell migration, proliferation and bone formation. The scaffold design and culture conditions are crucial for the limited diffusion distance of nutrients and oxygen. In static culture, decreased cell activity and irregular distribution occur within the scaffold. Dynamic conditions entail physical stimulation and constant medium perfusion imitating physiological nutrient supply and metabolite disposal. Therefore, we investigated the influence of different scaffold configurations and cultivation methods on human osteoblasts. Cells were seeded on three-dimensional porous Ti-6Al-4V scaffolds manufactured with selective laser melting (SLM) or electron beam melting (EBM) varying in porosity, pore size and basic structure (cubic, diagonal, pyramidal) and cultured under static and dynamic conditions. Cell viability, migration and matrix production were examined via mitochondrial activity assay, fluorescence staining and ELISA. All scaffolds showed an increasing cell activity and matrix production under static conditions over time. Expectations about the dynamic culture were only partially fulfilled, since it enabled proliferation alike the static one and enhanced cell migration. Overall, the SLM manufactured scaffold with the highest porosity, small pore size and pyramidal basic structure proved to be the most suitable structure for cell proliferation and migration.

Surface modifications of dental ceramic implants with different glass solder matrices: in vitro analyses with human primary osteoblasts and epithelial cells.

Ceramic materials show excellent esthetic behavior, along with an absence of hypersensitivity, making them a possible alternative implant material in dental surgery. However, their surface properties enable only limited osseointegration compared to titanium implants. Within this study, a novel surface coating technique for enhanced osseointegration was investigated biologically and mechanically. Specimens of tetragonal zirconia polycrystal (TZP) and aluminum toughened zirconia (ATZ) were modified with glass solder matrices in two configurations which mainly consisted of SiO2, Al2O3, K2O, and Na2O. The influence on human osteoblastic and epithelial cell viability was examined by means of a WST-1 assay as well as live/dead staining. A C1CP-ELISA was carried out to verify procollagen type I production. Uncoated/sandblasted ceramic specimens and sandblasted titanium surfaces were investigated as a reference. Furthermore, mechanical investigations of bilaterally coated pellets were conducted with respect to surface roughness and adhesive strength of the different coatings. These tests could demonstrate a mechanically stable implant coating with glass solder matrices. The coated ceramic specimens show enhanced osteoblastic and partly epithelial viability and matrix production compared to the titanium control. Hence, the new glass solder matrix coating could improve bone cell growth as a prerequisite for enhanced osseointegration of ceramic implants.

New Coating Technique of Ceramic Implants with Different Glass Solder Matrices for Improved Osseointegration-Mechanical Investigations.

Ceramics are a very popular material in dental implant technology due to their tribological properties, their biocompatibility and their esthetic appearance. However, their natural surface structure lacks the ability of proper osseointegration, which constitutes a crucial process for the stability and, thus, the functionality of a bone implant. We investigated the application of a glass solder matrix in three configurations-consisting mainly of SiO2, Al2O3, K2O and Na2O to TZP-A ceramic specimens. The corresponding adhesive strength and surface roughness of the coatings on ceramic specimens have been analyzed. Thereby, high adhesive strength (70.3 ± 7.9 MPa) was found for the three different coatings. The obtained roughness (Rz) amounted to 18.24 ± 2.48 µm in average, with significant differences between the glass solder configurations. Furthermore, one configuration was also tested after additional etching which did not lead to significant increase of surface roughness (19.37 ± 1.04 µm) or adhesive strength (57.2 ± 5.8 MPa). In conclusion, coating with glass solder matrix seems to be a promising surface modification technique that may enable direct insertion of ceramic implants in dental and orthopaedic surgery.