Development of a biodegradable microstent for minimally invasive treatment of Fallopian tube occlusions

Obstructions of the Fallopian tube represent one of the most common reasons for an unfulfilled desire to have children. Microstent technology opens up new therapeutic possibilities to restore the natural lumen of the Fallopian tube within a single treatment. Within the current work we developed a self-expandable biodegradable microstent for gynecological applications. Based on a novel microstent design, prototypes were manufactured from poly-L-lactide tubing by means of fs-laser cutting. Microstent prototypes were characterized morphologically by means of scanning electron microscopy and biaxial laser scanning. As manufactured, a microstents outside diameter of about 2.3 mm and a strut thickness / width of about 114 μm / 103 μm was measured. Mechanical characterization of microstents included bending as well as crimping and release behavior. After crimping to a minimum diameter of 0.8 mm and consecutive release, a microstent recovery to a diameter of 1.8 mm was found. Therefore, proof-of-concept for the self-expandable microstent could be successfully provided.

Application of 3R principles in small animal GLP testing of biomaterials

On the protection of animals used for scientific purposes, the EU Parliament adopted Directive 2010/63/EU. The essential factor is the 3R principle: Replacement, Reduction and Refinement. In 2013, the third amendment to the German Animal Welfare Act was revised and adapted to the European Directive. The majority of animals in science are used in basic research, as well as in translational and applied research. In medical research, animal experimentation is conducted to clarify previously unknown life processes and basic biological relationships, in order to improve diagnostics and treatment of human diseases. Before an animal experiment can be performed, it must be reported to and approved by the responsible authorities. The planned research project must be justified scientifically, and it must be demonstrated that the personnel and spatial/ technical prerequisites are in place to successfully complete the project. If all conditions are met, the approval can be granted, but may be subject to conditions. The guiding principle of essentiality also affects the procedure of the experiments: The number of animals used and the pain, suffering and damage caused to these animals must be limited to what is absolutely necessary. In this context, the 3R principle has to be applied. To obtain reliable results, it is essential that the laboratory animals are in normal physiological conditions and free of pain and fear. Scientific interest and animal welfare are therefore not in opposition, but rather mutually dependent. In our GLP (Good Laboratory Practice) laboratory we test new drug release systems for different biomedical applications in rabbits after careful selection of the animal model. Stress during animal experiments must be avoided as far as possible. Providing pain-killers and ensuring the best possible husbandry and care conditions are crucial for the animal’s wellbeing and absence of pain and anxiety. In the present work we report our different experience in a GLPcertified biomaterial test laboratory.

Actinomycin D for fibrosis management in ophthalmic implant surgery

Implants that feature a drug delivery system loaded with antifibrotic active drugs provide a promising approach to address postoperative complications caused by fibrosis. This study is intended to clarify whether Actinomycin D has an impact specifically on components of the extracellular matrix (ECM) and its formation in human primary fibroblasts of the Tenon capsule (hTF). Furthermore, the suitability of this agent in poly(N-vinylpyrrolidone)- poly(methylmethacrylate)(PVP-co-PMMA) as a drug delivery model is evaluated in drug incorporation and release studies. RT-qPCR revealed a significant downregulation of the fibrotic marker genes ACTA2, COL1A1 and FN1 in cells stimulated with TGF- β1 and additionally treated with Actinomycin D. However, these findings could only be confirmed on α- SMA protein level. collagen I and Fibronectin synthesis stayed unaffected. The diffusion based incorporation of Actinomycin D into the polymer model proved to be very effective. The release of the agent was retarded with a slightly prolonged kinetic. These findings make Actinomycin D a promising antifibrotic agent in ophthalmic implant surgery.

Safety evaluation of resveratrol as an active compound for drug-eluting cardiovascular implants

Resveratrol is a member of stilbenoids with promising anti-atherosclerotic properties. This hallmark makes it an extremely interesting candidate for local drug delivery to damaged tissue adjacent to the implant in order to reduce implant-related complications. For the regulatory approval drug-eluting medical devices have to be thoroughly tested for safety, efficacy and interactions with the surrounding tissue, including tests for sensitization among others. Studies for sensitization help to estimate the risk for an allergic reaction upon prolonged exposure to a chemical compound. Due to increased social and regulatory demand for replacement of animal experiments by in vitro approaches a number of reliable predictive non-animal tests have been developed. Here, we assessed the skin sensitization potential of resveratrol by the direct peptide reactivity assay (DPRA), one of the first non-animal tests adopted by the OECD.

Biocompatibility of magnetic iron oxide nanoparticles for biomedical applications

Magnetic nanoparticles are highly promising for the usage in various biomedical applications including magnetic particle imaging (MPI), cancer hyperthermia treatment or as drug carriers. The present study aims at assessing in vitro biocompatibility of two commercially available magnetic iron oxide nanoparticle formulations: dextran-based magnetic nanoparticle synomag-D and bionized nanoferrite BNF-starch. Biological performance of both nanoparticle formulations were studied in human endothelial cells by analyzing cell viability and nanoparticle internalization in order to judge their suitability as theranostics.

The blood compatibility challenge. Part 4: Surface modification for hemocompatible materials: Passive and active approaches to guide blood-material interactions

Biomedical devices in the blood flow disturb the fine-tuned balance of pro- and anti-coagulant factors in blood and vessel wall. Numerous technologies have been suggested to reduce coagulant and inflammatory responses of the body towards the device material, ranging from camouflage effects to permanent activity and further to a responsive interaction with the host systems. However, not all types of modification are suitable for all types of medical products. This review has a focus on application-oriented considerations of hemocompatible surface fittings. Thus, passive versus bioactive modifications are discussed along with the control of protein adsorption, stability of the immobilization, and the type of bioactive substance, biological or synthetic. Further considerations are related to the target system, whether enzymes or cells should be addressed in arterial or venous system, or whether the blood vessel wall is addressed. Recent developments like feedback controlled or self-renewing systems for drug release or addressing cellular regulation pathways of blood platelets and endothelial cells are paradigms for a generation of blood contacting devices, which are hemocompatible by cooperation with the host system. STATEMENT OF SIGNIFICANCE: This paper is part 4 of a series of 4 reviews discussing the problem of biomaterial associated thrombogenicity. The objective was to highlight features of broad agreement and provide commentary on those aspects of the problem that were subject to dispute. We hope that future investigators will update these reviews as new scholarship resolves the uncertainties of today.

Mutual influence of incorporated drugs in a dual drug delivery coating for cardiovascular applications

For a long-term efficient drug-eluting stent for vascular applications, the development of drug-loaded coating, combining the effective inhibition of smooth muscle cell proliferation while promoting the re-endothelialization, is a promising concept. However the mostly required simultaneous incorporation of drugs can influence decisively the stability, efficacy and release of the respective drug. Therefore, the mutual influence of a dual local drug delivery coatings based on poly(L-lactide-co-ε-caprolactone) (PLLA-co-CL) containing vascular endothelial growth factor (VEGF165) coupled to the surface and an embedded drug, such as fluorescein diacetate (FDAc) instead of Paclitaxel (PTX) on the in vitro drug release was investigated. Surprisingly, for the investigated coating the immobilized VEGF loading was enhanced and the release profile was accelerated by FDAc incorporation. Even a manifold increase for the in vitro released amounts of VEGF was detected. In contrast, the immobilization of VEGF seems to have a negligible influence on the in vitro FDAc release profiles.

Cell adhesion and viability of human endothelial cells on electrospun polymer scaffolds

The usage of electrospun polymer scaffolds is a promising approach for artificial heart valve design. This study aims at the evaluation of biological performance of nanofibrous polymer scaffolds poly(L-lactide) PLLA L210, PLLA L214 and polyamide-6 fabricated by electrospinning via analyzing viability, adhesion and morphology of human umbilical vein endothelial cells (EA.hy926). Nanofibrous surface topography was shown to influence cell phenotype and cell viability according to the observation of diminished cell spreading accompanied with reduced cell viability on nonwovens. Among those, highest biocompatibility was assessed for PLLA L214, although being generally low when compared to the planar control surface. Electrospinning was demonstrated as an innovative technique for the fabrication of advanced biomaterials aiming at guided cellular behavior as well as the design of novel implant platforms. A better understanding of cell–biomaterial interactions is desired to further improve implant development.

Quantitative trait loci controlling leaf appearance and curd initiation of cauliflower in relation to temperature

QTL regions on chromosomes C06 and C09 are involved in temperature dependent time to curd induction in cauliflower. Temperature is the main environmental factor influencing curding time of cauliflower (Brassica oleracea var. botrytis). Temperatures above 20-22 °C inhibit development towards curding even in many summer cultivars. To identify quantitative trait loci (QTL) controlling curding time and its related traits in a wide range of different temperature regimes from 12 to 27 °C, a doubled haploid (DH) mapping population segregating for curding time was developed and days to curd initiation (DCI), leaf appearance rate (LAR), and final leaf number (FLN) were measured. The population was genotyped with 176 single nucleotide polymorphism (SNP) markers. Composite interval mapping (CIM) revealed repeatedly detected QTL for DCI on C06 and C09. The estimated additive effect increased at high temperatures. Significant QTL × environment interactions (Q × E) for FLN and DCI on C06 and C09 suggest that these hotspot regions have major influences on temperature mediated curd induction. 25 % of the DH lines did not induce curds at temperatures higher than 22 °C. Applying a binary model revealed a QTL with LOD >15 on C06. Nearly all lines carrying the allele of the reliable early maturing parental line (PL) on that locus induced curds at high temperatures while only half of the DH lines carrying the allele of the unreliable PL reached the generative phase during the experiment. Large variation in LAR was observed. QTL for LAR were detected repeatedly in several environments on C01, C04 and C06. Negative correlations between LAR and DCI and QTL co-localizations on C04 and C06 suggest that LAR has also effects on development towards curd induction.

Osteoblasts with impaired spreading capacity benefit from the positive charges of plasma polymerised allylamine

Bone diseases such as osteoporosis, osteoarthritis and rheumatoid arthritis, impinge on the performance of orthopaedic implants by impairing bone regeneration. For this reason, the development of effective surface modifications supporting the ingrowth of implants in morbid bone tissue is essential. Our study is designed to elucidate if cells with restricted cell-function limiting adhesion processes benefit from plasma polymer deposition on titanium. We used the actin filament disrupting agent cytochalasin D (CD) as an experimental model for cells with impaired actin cytoskeleton. Indeed, the cell's capacity to adhere and spread was drastically reduced due to shortened actin filaments and vinculin contacts that were smaller. The coating of titanium with a positively charged nanolayer of plasma polymerised allylamine (PPAAm) abrogated these disadvantages in cell adhesion and the CD-treated osteoblasts were able to spread significantly. Interestingly, PPAAm increased spreading by causing enhanced vinculin number and contact length, but without significantly reorganising actin filaments. PPAAm with the monomer allylamine was deposited in a microwave-excited low-pressure plasma-processing reactor. Cell physiology was monitored by flow cytometry and confocal laser scanning microscopy, and the length and number of actin filaments was quantified by mathematical image processing. We showed that biomaterial surface modification with PPAAm could be beneficial even for osteoblasts with impaired cytoskeleton components. These insights into in vitro conditions may be used for the evaluation of future strategies to design implants for morbid bone tissue.

Genetic variation of temperature-regulated curd induction in cauliflower: elucidation of floral transition by genome-wide association mapping and gene expression analysis

Cauliflower (Brassica oleracea var. botrytis) is a vernalization-responsive crop. High ambient temperatures delay harvest time. The elucidation of the genetic regulation of floral transition is highly interesting for a precise harvest scheduling and to ensure stable market supply. This study aims at genetic dissection of temperature-dependent curd induction in cauliflower by genome-wide association studies and gene expression analysis. To assess temperature-dependent curd induction, two greenhouse trials under distinct temperature regimes were conducted on a diversity panel consisting of 111 cauliflower commercial parent lines, genotyped with 14,385 SNPs. Broad phenotypic variation and high heritability (0.93) were observed for temperature-related curd induction within the cauliflower population. GWA mapping identified a total of 18 QTL localized on chromosomes O1, O2, O3, O4, O6, O8, and O9 for curding time under two distinct temperature regimes. Among those, several QTL are localized within regions of promising candidate flowering genes. Inferring population structure and genetic relatedness among the diversity set assigned three main genetic clusters. Linkage disequilibrium (LD) patterns estimated global LD extent of r(2) = 0.06 and a maximum physical distance of 400 kb for genetic linkage. Transcriptional profiling of flowering genes FLOWERING LOCUS C (BoFLC) and VERNALIZATION 2 (BoVRN2) was performed, showing increased expression levels of BoVRN2 in genotypes with faster curding. However, functional relevance of BoVRN2 and BoFLC2 could not consistently be supported, which probably suggests to act facultative and/or might evidence for BoVRN2/BoFLC-independent mechanisms in temperature-regulated floral transition in cauliflower. Genetic insights in temperature-regulated curd induction can underpin genetically informed phenology models and benefit molecular breeding strategies toward the development of thermo-tolerant cultivars.

Membrane related dynamics and the formation of actin in cells growing on micro-topographies: a spatial computational model

Background

Intra-cellular processes of cells at the interface to an implant surface are influenced significantly by their extra-cellular surrounding. Specifically, when growing osteoblasts on titanium surfaces with regular micro-ranged geometry, filaments are shorter, less aligned and they concentrate at the top of the geometric structures. Changes to the cytoskeleton network, i. e., its localization, alignment, orientation, and lengths of the filaments, as well as the overall concentration and distribution of key-actors are induced. For example, integrin is distributed homogeneously, whereas integrin in activated state and vinculin, both components of focal adhesions, have been found clustered on the micro-ranged geometries. Also, the concentration of Rho, an intracellular signaling protein related to focal adhesion regulation, was significantly lower.

Results

To explore whether regulations associated with the focal adhesion complex can be responsible for the changed actin filament patterns, a spatial computational model has been developed using ML-Space, a rule-based model description language, and its associated Brownian-motion-based simulator. The focus has been on the deactivation of cofilin in the vicinity of the focal adhesion complex. The results underline the importance of sensing mechanisms to support a clustering of actin filament nucleations on the micro-ranged geometries, and of intracellular diffusion processes, which lead to spatially heterogeneous distributions of active (dephosphorylated) cofilin, which in turn influences the organization of the actin network. We find, for example, that the spatial heterogeneity of key molecular actors can explain the difference in filament lengths in cells on different micro-geometries partly, but to explain the full extent, further model assumptions need to be added and experimentally validated. In particular, our findings and hypothesis referring to the role, distribution, and amount of active cofilin have still to be verified in wet-lab experiments.

Conclusion

Letting cells grow on surface structures is a possibility to shed new light on the intricate mechanisms that relate membrane and actin related dynamics in the cell. Our results demonstrate the need for declarative expressive spatial modeling approaches that allow probing different hypotheses, and the central role of the focal adhesion complex not only for nucleating actin filaments, but also for regulating possible severing agents locally.

Automatic Actin Filament Quantification of Osteoblasts and Their Morphometric Analysis on Microtextured Silicon-Titanium Arrays

Microtexturing of implant surfaces is of major relevance in the endeavor to improve biorelevant implant designs. In order to elucidate the role of biomaterial’s topography on cell physiology, obtaining quantitative correlations between cellular behavior and distinct microarchitectural properties is in great demand. Until now, the microscopically observed reorganization of the cytoskeleton on structured biomaterials has been difficult to convert into data. We used geometrically microtextured silicon-titanium arrays as a model system. Samples were prepared by deep reactive-ion etching of silicon wafers, resulting in rectangular grooves (width and height: 2 µm) and cubic pillars (pillar dimensions: 2 × 2 × 5 and 5 × 5 × 5 µm); finally sputter-coated with 100 nm titanium. We focused on the morphometric analysis of MG-63 osteoblasts, including a quantification of the actin cytoskeleton. By means of our novel software FilaQuant, especially developed for automatic actin filament recognition, we were first able to quantify the alterations of the actin network dependent on the microtexture of a material surface. The cells’ actin fibers were significantly reduced in length on the pillared surfaces versus the grooved array (4–5 fold) and completely reorganized on the micropillars, but without altering the orientation of cells. Our morpho-functional approach opens new possibilities for the data correlation of cell-material interactions.

Mutational analysis of 9 different tumour-associated genes in human malignant mesothelioma cell lines

Seven tumour suppressor genes (Chk1, Chk2, Apaf1, Rb1, p53, p16(INK4a) and p14(ARF)) and two oncogenes (N-ras and BRAF) were screened in nine human malignant melanoma (HMM) cell lines for point mutations or small deletions/insertions by DGGE, TGGE and SCCP analysis. For the first time in human mesothelioma, Chk1 gene mutations were detected in two of the nine investigated HMM cell lines. P53 gene mutations were found in three cell lines and p16(INK4a) mutations in 5. Mutation of the Chk1 gene implies a novel disruption mechanism of the p53 pathway in HMM, without affecting p53 itself. According to our knowledge, this is the first mutation screening of Chk1, Chk2, Apaf1 and Rb1 in human malignant mesothelioma.