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Contains fulltext : 306388.pdf (Publisher’s version ) (Open Access), Despite the immense need for effective treatment of spinal cord injury (SCI), no successful repair strategy has yet been clinically implemented. Multifunctional biomaterials, based on porcine adipose tissue-derived extracellular matrix (adECM) and reduced graphene oxide (rGO), were recently shown to stimulate in vitro neural stem cell growth and differentiation. Nevertheless, their functional performance in clinically more relevant in vivo conditions remains largely unknown. Before clinical application of these adECM-rGO nanocomposites can be considered, a rigorous assessment of the cytotoxicity and biocompatibility of these biomaterials is required. For instance, xenogeneic adECM scaffolds could still harbour potential immunogenicity following decellularization. In addition, the toxicity of rGO has been studied before, yet often in experimental settings that do not bear relevance to regenerative medicine. Therefore, the present study aimed to assess both the in vitro as well as in vivo safety of adECM and adECM-rGO scaffolds. First, pulmonary, renal and hepato-cytotoxicity as well as macrophage polarization studies showed that scaffolds were benign invitro. Then, a laminectomy was performed at the 10th thoracic vertebra, and scaffolds were implanted directly contacting the spinal cord. For a total duration of 6 weeks, animal welfare was not negatively affected. Histological analysis demonstrated the degradation of adECM scaffolds and subsequent tissue remodeling. Graphene-based scaffolds showed a very limited fibrous encapsulation, while rGO sheets were engulfed by foreign body giant cells. Furthermore, all scaffolds were infiltrated by macrophages, which were largely polarized towards a pro-regenerative phenotype. Lastly, organ-specific histopathology and biochemical analysis of blood did not reveal any adverse effects. In summary, both adECM and adECM-rGO implants were biocompatible upon laminectomy while establishing a pro-regenerative microenvironment, which ju, 01 juni 2024

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Item does not contain fulltext, The large number of animal models used in spinal cord injury (SCI) research complicates the objective selection of the most appropriate model to investigate the efficacy of biomaterial-based therapies. This systematic review aims to identify a list of relevant animal models of SCI by evaluating the confirmation of SCI and animal survival in all published SCI models used in biomaterials research up until April 2021. A search in PubMed and Embase based on "spinal cord injury," "animal models," and "biomaterials" yielded 4606 papers, 393 of which were further evaluated. A total of 404 individual animal experiments were identified based on type of SCI, level of SCI, and the sex, species, and strain of the animals used. Finally, a total of 149 unique animal models were comparatively evaluated, which led to the generation of an evidence-based list of well-documented mid-thoracic rat models of SCI. These models were used most often, clearly confirmed SCI, and had relatively high survival rates, and therefore could serve as a future starting point for studying novel biomaterial-based therapies for SCI. Furthermore, the review discusses (1) the possible risk of bias in SCI animal models, (2) the difficulty in replication of such experiments due to frequent poor reporting of the methods and results, and (3) the clinical relevance of the currently utilized models. Systematic review registration: The study was prospectively registered in PROSPERO, registration number CRD42019141162. Impact statement Studies on biomaterial-based therapies within the field of spinal cord injury (SCI) research show a large inconsistency concerning the selection of animal models. This review goes beyond summarizing the existing gaps between experimental and clinical SCI by systematically evaluating all animal models used within this field. The models identified by this work were used most often, clearly confirmed SCI, and had a relatively high survival rate. This evidence-based list of well-documen

Item does not contain fulltext, The large number of animal models used in spinal cord injury (SCI) research complicates the objective selection of the most appropriate model to investigate the efficacy of biomaterial-based therapies. This systematic review aims to identify a list of relevant animal models of SCI by evaluating the confirmation of SCI and animal survival in all published SCI models used in biomaterials research up until April 2021. A search in PubMed and Embase based on "spinal cord injury," "animal models," and "biomaterials" yielded 4606 papers, 393 of which were further evaluated. A total of 404 individual animal experiments were identified based on type of SCI, level of SCI, and the sex, species, and strain of the animals used. Finally, a total of 149 unique animal models were comparatively evaluated, which led to the generation of an evidence-based list of well-documented mid-thoracic rat models of SCI. These models were used most often, clearly confirmed SCI, and had relatively high survival rates, and therefore could serve as a future starting point for studying novel biomaterial-based therapies for SCI. Furthermore, the review discusses (1) the possible risk of bias in SCI animal models, (2) the difficulty in replication of such experiments due to frequent poor reporting of the methods and results, and (3) the clinical relevance of the currently utilized models. Systematic review registration: The study was prospectively registered in PROSPERO, registration number CRD42019141162. Impact statement Studies on biomaterial-based therapies within the field of spinal cord injury (SCI) research show a large inconsistency concerning the selection of animal models. This review goes beyond summarizing the existing gaps between experimental and clinical SCI by systematically evaluating all animal models used within this field. The models identified by this work were used most often, clearly confirmed SCI, and had a relatively high survival rate. This evidence-based list of well-documen

Contains fulltext : 195862.pdf (publisher's version ) (Open Access)

An analysis of improving efficiency of aircraft engine turbines by means of improvement of composition of sealing coatings used in labyrinth seals was made. It was established that a number of contradictory requirements to properties of such coatings are imposed at the initial stage of engine running-in and during further operation. Main types of damage of above coatings used in the design of labyrinth seals during operation of gas turbine engines were shown. In connection with the necessity of raising temperature of gases in turbines of aircraft engines, it was proposed to additionally dope the serial nickel-based coatings with yttrium-containing master alloys. The results of study of influence of doping of the wearing-in sealing coatings on operating properties in conditions of action of a high-temperature gas flow were presented. It was found that doping of the KNA-82 serial coating with a multicomponent Co-Ni-Cr-Al-Y master alloy is the most rational solution.It was established that the use of the developed coating in a temperature range of 1,100...1,200 °C makes it possible to reduce specific consumption of fuel by aircraft engines by improving turbine efficiency and prevent wear of the end faces of ridges of the rotor labyrinth seal. Based on simulation of flow in the labyrinth seal clearance by numerical method, it was shown that the use of the developed coating materials in seals of the compressor turbine and the free turbine makes it possible to reduce amount of cooling air leakage into the turbine air-gas channel by reducing wear of tops of the labyrinth rotor seal ridge, Виконано аналіз підвищення ефективності турбін авіаційних двигунів шляхом вдосконалення складу ущільнювальних покриттів, що застосовуються в лабіринтних ущільненнях. Встановлено, що до таких покриттів висувається ряд суперечливих вимог, щодо їх властивостей на початковому етапі обкатки двигуна і при подальшій експлуатації. Показано основні види пошкоджень зазначених покриттів застосовуваних у конструкції лабіринтних ущільнень в процесі експлуатації газотурбінних двигунів. В зв’язку з необхідністю підвищення температури газів в турбіні авіаційних двигунів запропоновано додатково легувати серійні покриття на нікелевій основі ітрійвміщуючими лігатурами.Наведено результати дослідження впливу легування ущільнювальних покриттів, що прироблюються, на експлуатаційні властивості в умовах впливу високотемпературного газового потоку. Визначено, що найбільш раціональним є легування серійного покриття КНА-82 багатокомпонентною лігатурою Co-Ni-Cr-Al-Y.Встановлено, що застосування розробленого покриття в діапазоні температур 1100...1200 °С дозволяє знизити питомі витрати палива авіаційних двигунів за рахунок підвищення коефіцієнта корисної дії турбіни, а також запобігти зношуванню торцевих поверхонь гребінців лабіринтного ущільнення ротора. На підставі моделювання плину потоку в зазорі лабіринтного ущільнення чисельним методом показано, що застосування розроблених матеріалів покриттів в конструкції ущільнень турбіни компресора і вільної турбіни дозволяє знизити величину витоку охолоджуючого повітря в проточну частину турбіни за рахунок зменшення зносу гребінців лабіринтних ущільнень ротора, Выполнен анализ повышения эффективности турбин авиационных двигателей путем совершенствования состава уплотнительных покрытий, применяемых в лабиринтных уплотнениях. Установлено, что к таким покрытиям выдвигается ряд противоречивых требований к свойствам на начальном этапе обкатки двигателя и при дальнейшей эксплуатации. Показаны основные виды повреждений указанных покрытий, применяемых в конструкции лабиринтных уплотнений в процессе эксплуатации газотурбинных двигателей. В связи с необходимостью повышения температуры газов в турбине авиационных двигателей предложено дополнительно легировать серийные покрытия на никелевой основе иттрийсодержащими лигатурами. Приведены результаты исследования влияния легирования прирабатываемых уплотнительных покрытий на эксплуатационные свойства в условиях воздействия высокотемпературного газового потока. Определено, что наиболее рациональным является легирование серийного покрытия КНА-82 многокомпонентной лигатурой Co-Ni-Cr-Al-Y.Установлено, что применение разработанного покрытия в диапазоне температур 1100 ... 1200 °С позволяет снизить удельный расход топлива авиационных двигателей за счет повышения коэффициента полезного действия турбины, а также предотвратить износ торцевых поверхностей гребешков лабиринтного уплотнения ротора. На основании моделирования течения потока в зазоре лабиринтного уплотнения численным методом показано, что применение разработанных материалов покрытий в конструкции уплотнений турбины компрессора и свободной турбины позволяет снизить величину утечки охлаждающего воздуха в проточную часть турбины за счет уменьшения износа гребней лабиринтных уплотнений ротора

Xiaolin Zhang,1,2,* Jiankang Song,3,* Alexey Klymov,3,* Yang Zhang,3 Leonie de Boer,1 John A Jansen,3 Jeroen JJP van den Beucken,3 Fang Yang,3 Sebastian AJ Zaat,1,* Sander CG Leeuwenburgh3,* 1Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; 2Department of Biomaterials Science and Technology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, the Netherlands; 3Department of Biomaterials, Radboud University Medical Centre, Nijmegen, the Netherlands *These authors contributed equally to this work Background: Infections such as biomaterial-associated infection and osteomyelitis are often associated with intracellular survival of bacteria (eg, Staphylococcus aureus). Treatment of these infections remains a major challenge due to the low intracellular efficacy of many antibiotics. Therefore, local delivery systems are urgently required to improve the therapeutic efficacy of antibiotics by enabling their intracellular delivery. Purpose: To assess the potential of gelatin nanospheres as carriers for local delivery of vancomycin into macrophages of zebrafish larvae in vivo and into THP-1-derived macrophages in vitro using fluorescence microscopy. Materials and methods: Fluorescently labeled gelatin nanospheres were prepared and injected into transgenic zebrafish larvae with fluorescent macrophages. Both the biodistribution of gelatin nanospheres in zebrafish larvae and the co-localization of vancomycin-loaded gelatin nanospheres with zebrafish macrophages in vivo and uptake by THP-1-derived macrophages in vitro were studied. In addition, the effect of treatment with vancomycin-loaded gelatin nanospheres on survival of S. aureus-infected zebrafish larvae was investigated. Results: Internalization of vancomycin-loaded gelatin nanospheres by macrophages was observed qualitatively both in vivo and in vitro. Systemically delive

Contains fulltext : 195862.pdf (publisher's version ) (Open Access)

Contains fulltext : 195862.pdf (publisher's version ) (Open Access)

Xiaolin Zhang,1,2,* Jiankang Song,3,* Alexey Klymov,3,* Yang Zhang,3 Leonie de Boer,1 John A Jansen,3 Jeroen JJP van den Beucken,3 Fang Yang,3 Sebastian AJ Zaat,1,* Sander CG Leeuwenburgh3,* 1Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; 2Department of Biomaterials Science and Technology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, the Netherlands; 3Department of Biomaterials, Radboud University Medical Centre, Nijmegen, the Netherlands *These authors contributed equally to this work Background: Infections such as biomaterial-associated infection and osteomyelitis are often associated with intracellular survival of bacteria (eg, Staphylococcus aureus). Treatment of these infections remains a major challenge due to the low intracellular efficacy of many antibiotics. Therefore, local delivery systems are urgently required to improve the therapeutic efficacy of antibiotics by enabling their intracellular delivery. Purpose: To assess the potential of gelatin nanospheres as carriers for local delivery of vancomycin into macrophages of zebrafish larvae in vivo and into THP-1-derived macrophages in vitro using fluorescence microscopy. Materials and methods: Fluorescently labeled gelatin nanospheres were prepared and injected into transgenic zebrafish larvae with fluorescent macrophages. Both the biodistribution of gelatin nanospheres in zebrafish larvae and the co-localization of vancomycin-loaded gelatin nanospheres with zebrafish macrophages in vivo and uptake by THP-1-derived macrophages in vitro were studied. In addition, the effect of treatment with vancomycin-loaded gelatin nanospheres on survival of S. aureus-infected zebrafish larvae was investigated. Results: Internalization of vancomycin-loaded gelatin nanospheres by macrophages was observed qualitatively both in vivo and in vitro. Systemically delive

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Contains fulltext : 177168.pdf (publisher's version ) (Closed access), Multicompartment particles, which are particles composed of smaller building units, have gained considerable interest during the past decade to facilitate simultaneous and differential delivery of several biomolecules in various applications. Supercritical carbon dioxide (CO2) processing is an industrial technology widely used for large-scale synthesis and processing of materials. However, the application of this technology for production of multicompartment particles from colloidal particles has not yet been explored. Here, we report the formation of raspberry-like gelatin (RLG) microparticles composed of gelatin nanoparticles as colloidal building blocks through supercritical CO2 processing. We show that these RLG microparticles exhibit a high stability upon dispersion in aqueous media without requiring chemical cross-linking. We further demonstrate that these microparticles are cytocompatible and facilitate differential release of two different model compounds. The strategy presented here can be utilized as a cost-effective route for production of various types of multicompartment particles using colloidal particles with suitable interparticle interactions. STATEMENT OF SIGNIFICANCE: Multicompartment particles have gained considerable interest during the past decade to facilitate simultaneous and differential delivery of multiple biomolecules in various biomedical applications. Nevertheless, common methods employed for the production of such particles are often complex and only offer small-scale production. Here, we report the formation of raspberry-like gelatin (RLG) microparticles composed of gelatin nanoparticles as colloidal building blocks through supercritical CO2 processing. We show that these microparticles are cytocompatible and facilitate differential release of two model compounds with different molecular sizes, promising successful applications in various biomedical areas. Summarizing, this paper presents a novel strategy that can be utilized as a cos

Injectable composite colloidal gels are developed for regeneration of osteoporotic bone defects through a bottom-up assembly from bisphosphonate-functionalized gelatin and bioactive glass particles. Upon bisphosphonate functionalization, gelatin nanoparticles show superior adhesion toward bioactive glass particles, resulting in elastic composite gels. By tuning their composition, these composite colloidal gels combine mechanical robustness with self-healing ability. The composite colloidal gels support cell proliferation and differentiation in vitro without requiring any osteogenic supplement. In vivo evaluation of the composite colloidal gels reveals their capacity to support the regeneration of osteoporotic bone defects. Furthermore, the bisphosphonate modification of gelatin induces a therapeutic effect on the peri-implantation region by enhancing the bone density of the osteoporotic bone tissue. Consequently, these composite colloidal gels offer new therapeutic opportunities for treatment of osteoporotic bone defects.

Item does not contain fulltext, Development of novel and effective drug delivery systems for controlled release of bioactive molecules is of critical importance in the field of regenerative medicine. Here, oppositely charged gelatin nanospheres are incorporated into silk fibroin nanofibers through a colloidal electrospinning technique. A novel fibrous nano-in-nano drug delivery system is fabricated without the use of any organic solvent. The distribution of fluorescently labeled gelatin A and B nanospheres inside the nanofibers can be fine-tuned by simple adjustment of the weight ratio between the nanospheres and the relative feeding rate of core and shell solutions containing nanospheres by using single and coaxial nozzle electrospinning, respectively. Incorporation of vancomycin-loaded gelatin B nanospheres into the silk fibroin nanofibrous membranes results in a more sustained release of vancomycin, compared to the gelatin nanospheres free membranes. In addition, these membranes exhibit excellent and prolonged antibacterial effects against Staphylococcus aureus. Moreover, these membranes support the attachment, spreading, and proliferation of periodontal ligament cells. These results suggest that the beneficial properties of gelatin nanospheres can be exploited to improve the biological functionality of electrospun nanofibrous silk fibroin membranes.

Item does not contain fulltext

Contains fulltext : 177168.pdf (publisher's version ) (Closed access), Multicompartment particles, which are particles composed of smaller building units, have gained considerable interest during the past decade to facilitate simultaneous and differential delivery of several biomolecules in various applications. Supercritical carbon dioxide (CO2) processing is an industrial technology widely used for large-scale synthesis and processing of materials. However, the application of this technology for production of multicompartment particles from colloidal particles has not yet been explored. Here, we report the formation of raspberry-like gelatin (RLG) microparticles composed of gelatin nanoparticles as colloidal building blocks through supercritical CO2 processing. We show that these RLG microparticles exhibit a high stability upon dispersion in aqueous media without requiring chemical cross-linking. We further demonstrate that these microparticles are cytocompatible and facilitate differential release of two different model compounds. The strategy presented here can be utilized as a cost-effective route for production of various types of multicompartment particles using colloidal particles with suitable interparticle interactions. STATEMENT OF SIGNIFICANCE: Multicompartment particles have gained considerable interest during the past decade to facilitate simultaneous and differential delivery of multiple biomolecules in various biomedical applications. Nevertheless, common methods employed for the production of such particles are often complex and only offer small-scale production. Here, we report the formation of raspberry-like gelatin (RLG) microparticles composed of gelatin nanoparticles as colloidal building blocks through supercritical CO2 processing. We show that these microparticles are cytocompatible and facilitate differential release of two model compounds with different molecular sizes, promising successful applications in various biomedical areas. Summarizing, this paper presents a novel strategy that can be utilized as a cos

Item does not contain fulltext, Development of novel and effective drug delivery systems for controlled release of bioactive molecules is of critical importance in the field of regenerative medicine. Here, oppositely charged gelatin nanospheres are incorporated into silk fibroin nanofibers through a colloidal electrospinning technique. A novel fibrous nano-in-nano drug delivery system is fabricated without the use of any organic solvent. The distribution of fluorescently labeled gelatin A and B nanospheres inside the nanofibers can be fine-tuned by simple adjustment of the weight ratio between the nanospheres and the relative feeding rate of core and shell solutions containing nanospheres by using single and coaxial nozzle electrospinning, respectively. Incorporation of vancomycin-loaded gelatin B nanospheres into the silk fibroin nanofibrous membranes results in a more sustained release of vancomycin, compared to the gelatin nanospheres free membranes. In addition, these membranes exhibit excellent and prolonged antibacterial effects against Staphylococcus aureus. Moreover, these membranes support the attachment, spreading, and proliferation of periodontal ligament cells. These results suggest that the beneficial properties of gelatin nanospheres can be exploited to improve the biological functionality of electrospun nanofibrous silk fibroin membranes.

Contains fulltext : 177168.pdf (publisher's version ) (Closed access), Multicompartment particles, which are particles composed of smaller building units, have gained considerable interest during the past decade to facilitate simultaneous and differential delivery of several biomolecules in various applications. Supercritical carbon dioxide (CO2) processing is an industrial technology widely used for large-scale synthesis and processing of materials. However, the application of this technology for production of multicompartment particles from colloidal particles has not yet been explored. Here, we report the formation of raspberry-like gelatin (RLG) microparticles composed of gelatin nanoparticles as colloidal building blocks through supercritical CO2 processing. We show that these RLG microparticles exhibit a high stability upon dispersion in aqueous media without requiring chemical cross-linking. We further demonstrate that these microparticles are cytocompatible and facilitate differential release of two different model compounds. The strategy presented here can be utilized as a cost-effective route for production of various types of multicompartment particles using colloidal particles with suitable interparticle interactions. STATEMENT OF SIGNIFICANCE: Multicompartment particles have gained considerable interest during the past decade to facilitate simultaneous and differential delivery of multiple biomolecules in various biomedical applications. Nevertheless, common methods employed for the production of such particles are often complex and only offer small-scale production. Here, we report the formation of raspberry-like gelatin (RLG) microparticles composed of gelatin nanoparticles as colloidal building blocks through supercritical CO2 processing. We show that these microparticles are cytocompatible and facilitate differential release of two model compounds with different molecular sizes, promising successful applications in various biomedical areas. Summarizing, this paper presents a novel strategy that can be utilized as a cos

Injectable composite colloidal gels are developed for regeneration of osteoporotic bone defects through a bottom-up assembly from bisphosphonate-functionalized gelatin and bioactive glass particles. Upon bisphosphonate functionalization, gelatin nanoparticles show superior adhesion toward bioactive glass particles, resulting in elastic composite gels. By tuning their composition, these composite colloidal gels combine mechanical robustness with self-healing ability. The composite colloidal gels support cell proliferation and differentiation in vitro without requiring any osteogenic supplement. In vivo evaluation of the composite colloidal gels reveals their capacity to support the regeneration of osteoporotic bone defects. Furthermore, the bisphosphonate modification of gelatin induces a therapeutic effect on the peri-implantation region by enhancing the bone density of the osteoporotic bone tissue. Consequently, these composite colloidal gels offer new therapeutic opportunities for treatment of osteoporotic bone defects.

Contains fulltext : 167419.pdf (publisher's version ) (Closed access), In the present study, a method was developed to reproduce two nanogrooved patterns (groove width/ridge width/depth: 150/150/50 nm and 200/800/70 nm) into cylindrical epoxy resin implants, which were subsequently coated with 20 nm of titanium. Also, implants with a conventional surface roughness (Rq=1.6 mum) were produced. After cytocompatibility analysis of the produced surfaces, implants were installed into the femoral condyle of rats for 4 and 8 weeks. The histomorphometrical analysis of bone volume in a 100 mum wide zone close to the implant surface showed that only for the 200/800 grooves the amount of bone increased significantly between 4 and 8 weeks of implantation. In addition, at the late time point only implants with the 200/800 pattern revealed a significantly higher bone volume compared to the rough controls. In conclusion, the 200/800 grooved pattern can positively influence bone volume adjacent to the implant surface, and should be evaluated and optimized in further (pre-)clinical studies.

Radboud Universiteit Nijmegen, 26 januari 2016, Promotor : Jansen, J.A. Co-promotor : Walboomers, X.F., Contains fulltext : 150213.pdf (publisher's version ) (Open Access)

Item does not contain fulltext, Micro- and nanotextured biomaterial surfaces have been widely studied for their capacity to drive the regeneration of organized tissues. Nanotopographical features in the shape of groove-ridge patterns aim at mimicking the extracellular matrix organization. However, to date, a wide array of groove and ridge sizes has been described. In this work, we therefore tested a device composed of a multipatterned array consisting of six patterns of radially arranged parallel nanogrooves, with a pitch ranging from 0 to 1000 nm and a depth ranging from 0 to 170 nm, to be used as a tool for the expeditious and simultaneous screening of surface topographies aiming the regeneration of anisotropically organized tissues such as ligament. The topographies were reproduced in (1) epoxy resin or (2) membranes produced by the crosslinking of platelet lysate (PL) with genipin (gPL). Both materials were seeded with periodontal ligament cells (PDLCs) and the proliferation, migration, as well as cell alignment were assessed. The effect of topography in PDLCs was only evident in terms of cell organization, resulting in a highly anisotropic organization of the cells for the 1000 and 600 nm patterns, and in an increased isotropic organization for shallower topographies. Overall, our results suggest that this multipatterned system can be a valuable diagnostic tool for biomaterials aiming at the regeneration of anisotropically organized tissues, such as periodontal ligament.

Item does not contain fulltext, The composition of calcium phosphate (CaP) ceramics in combination with surface features have been shown to influence biological performance, and micro- and nano-scale topography is known to stimulate osteogenic differentiation of mesenchymal stromal cells (MSCs). In view of this, adipose tissue derived MSCs were cultured on CaP disks featuring hemispherical concavities of various sizes (440, 800 or 1800 mum diameter). It was hypothesized that (i) surface concavities would promote cell proliferation, cellular organization within the concavities, and osteogenic differentiation, as a result of a more pronounced 3D micro-environment and CaP nucleation in concavities, and (ii) MSC proliferation and osteogenic differentiation would increase with smaller concavity size due to more rapidly occurring 3D cell-cell interactions. We found that concavities indeed affect cell proliferation, with 440 mum concavities increasing cell proliferation to a larger extent compared to 800 and 1800 mum concavities as well as planar surfaces. Additionally, concavity size influenced 3D cellular organization within the concavity volume. Interestingly, concavity size promoted osteogenic differentiation of cells, as evidenced by increased osteocalcin gene expression in 440 mum concavities, and osteocalcin staining predominantly for 440 and 800 mum concavities, but not for 1800 mum concavities and only slightly for planar surface controls.

1 februari 2016, Item does not contain fulltext, The current work evaluated the influence of nanoscale surface-topographies in combination with a calcium phosphate (CaP) coating on acellular and cellular surface mineralization. Four groups of substrates were produced, including smooth, grooved (940nm pitch, 430nm groove width, 185nm depth), smooth coated, and grooved coated. The substrates were characterized by scanning/transmission electron microscopy and atomic force microscopy. Osteoblast-like MC3T3 cells were cultured on the substrates for a period up to 35days under osteogenic conditions. Differentiation was observed by alkaline phosphatase assay and PCR of collagen I (COLI), osteopontin (OPN), osteocalcin (OC), bone-morphogenic protein 2 (BMP2), and bone sialoprotein (BSP). Mineralization was quantified by a calcium assay and Alizarin Red staining. In addition, acellular mineralization was determined after incubation of substrates in just cell culture medium without cells. Results showed that a reproducible nano-metric ( approximately 50nm) CaP-layer could be applied on the substrates, without losing the integrity of the topographical features. While no relevant differences were found for cell viability, cells on smooth surfaces proliferated for a longer period than cells on grooved substrates. In addition, differentiation was affected by topographies, as indicated by an increased expression of OC, OPN and ALP activity. Deposition of a CaP coating significantly increased the acellular mineralization of smooth as well grooved substrate-surfaces. However, this mineralizing effect was strongly reduced in the presence of cells. In the cell seeded situation, mineralization was significantly increased by the substrate topography, while only a minor additive effect of the coating was observed. In conclusion, the model presented herein can be exploited for experimental evaluation of cell-surface interaction processes and optimization of bone-anchoring capability of implants. The model showed that substrates modified

Contains fulltext : 167419.pdf (publisher's version ) (Closed access), In the present study, a method was developed to reproduce two nanogrooved patterns (groove width/ridge width/depth: 150/150/50 nm and 200/800/70 nm) into cylindrical epoxy resin implants, which were subsequently coated with 20 nm of titanium. Also, implants with a conventional surface roughness (Rq=1.6 mum) were produced. After cytocompatibility analysis of the produced surfaces, implants were installed into the femoral condyle of rats for 4 and 8 weeks. The histomorphometrical analysis of bone volume in a 100 mum wide zone close to the implant surface showed that only for the 200/800 grooves the amount of bone increased significantly between 4 and 8 weeks of implantation. In addition, at the late time point only implants with the 200/800 pattern revealed a significantly higher bone volume compared to the rough controls. In conclusion, the 200/800 grooved pattern can positively influence bone volume adjacent to the implant surface, and should be evaluated and optimized in further (pre-)clinical studies.

Radboud Universiteit Nijmegen, 26 januari 2016, Promotor : Jansen, J.A. Co-promotor : Walboomers, X.F., Contains fulltext : 150213.pdf (publisher's version ) (Open Access)

Item does not contain fulltext, Micro- and nanotextured biomaterial surfaces have been widely studied for their capacity to drive the regeneration of organized tissues. Nanotopographical features in the shape of groove-ridge patterns aim at mimicking the extracellular matrix organization. However, to date, a wide array of groove and ridge sizes has been described. In this work, we therefore tested a device composed of a multipatterned array consisting of six patterns of radially arranged parallel nanogrooves, with a pitch ranging from 0 to 1000 nm and a depth ranging from 0 to 170 nm, to be used as a tool for the expeditious and simultaneous screening of surface topographies aiming the regeneration of anisotropically organized tissues such as ligament. The topographies were reproduced in (1) epoxy resin or (2) membranes produced by the crosslinking of platelet lysate (PL) with genipin (gPL). Both materials were seeded with periodontal ligament cells (PDLCs) and the proliferation, migration, as well as cell alignment were assessed. The effect of topography in PDLCs was only evident in terms of cell organization, resulting in a highly anisotropic organization of the cells for the 1000 and 600 nm patterns, and in an increased isotropic organization for shallower topographies. Overall, our results suggest that this multipatterned system can be a valuable diagnostic tool for biomaterials aiming at the regeneration of anisotropically organized tissues, such as periodontal ligament.

Item does not contain fulltext, The composition of calcium phosphate (CaP) ceramics in combination with surface features have been shown to influence biological performance, and micro- and nano-scale topography is known to stimulate osteogenic differentiation of mesenchymal stromal cells (MSCs). In view of this, adipose tissue derived MSCs were cultured on CaP disks featuring hemispherical concavities of various sizes (440, 800 or 1800 mum diameter). It was hypothesized that (i) surface concavities would promote cell proliferation, cellular organization within the concavities, and osteogenic differentiation, as a result of a more pronounced 3D micro-environment and CaP nucleation in concavities, and (ii) MSC proliferation and osteogenic differentiation would increase with smaller concavity size due to more rapidly occurring 3D cell-cell interactions. We found that concavities indeed affect cell proliferation, with 440 mum concavities increasing cell proliferation to a larger extent compared to 800 and 1800 mum concavities as well as planar surfaces. Additionally, concavity size influenced 3D cellular organization within the concavity volume. Interestingly, concavity size promoted osteogenic differentiation of cells, as evidenced by increased osteocalcin gene expression in 440 mum concavities, and osteocalcin staining predominantly for 440 and 800 mum concavities, but not for 1800 mum concavities and only slightly for planar surface controls.

01 februari 2016, Item does not contain fulltext, The current work evaluated the influence of nanoscale surface-topographies in combination with a calcium phosphate (CaP) coating on acellular and cellular surface mineralization. Four groups of substrates were produced, including smooth, grooved (940nm pitch, 430nm groove width, 185nm depth), smooth coated, and grooved coated. The substrates were characterized by scanning/transmission electron microscopy and atomic force microscopy. Osteoblast-like MC3T3 cells were cultured on the substrates for a period up to 35days under osteogenic conditions. Differentiation was observed by alkaline phosphatase assay and PCR of collagen I (COLI), osteopontin (OPN), osteocalcin (OC), bone-morphogenic protein 2 (BMP2), and bone sialoprotein (BSP). Mineralization was quantified by a calcium assay and Alizarin Red staining. In addition, acellular mineralization was determined after incubation of substrates in just cell culture medium without cells. Results showed that a reproducible nano-metric ( approximately 50nm) CaP-layer could be applied on the substrates, without losing the integrity of the topographical features. While no relevant differences were found for cell viability, cells on smooth surfaces proliferated for a longer period than cells on grooved substrates. In addition, differentiation was affected by topographies, as indicated by an increased expression of OC, OPN and ALP activity. Deposition of a CaP coating significantly increased the acellular mineralization of smooth as well grooved substrate-surfaces. However, this mineralizing effect was strongly reduced in the presence of cells. In the cell seeded situation, mineralization was significantly increased by the substrate topography, while only a minor additive effect of the coating was observed. In conclusion, the model presented herein can be exploited for experimental evaluation of cell-surface interaction processes and optimization of bone-anchoring capability of implants. The model showed that substrates modified

Item does not contain fulltext, Micro- and nanotextured biomaterial surfaces have been widely studied for their capacity to drive the regeneration of organized tissues. Nanotopographical features in the shape of groove-ridge patterns aim at mimicking the extracellular matrix organization. However, to date, a wide array of groove and ridge sizes has been described. In this work, we therefore tested a device composed of a multipatterned array consisting of six patterns of radially arranged parallel nanogrooves, with a pitch ranging from 0 to 1000 nm and a depth ranging from 0 to 170 nm, to be used as a tool for the expeditious and simultaneous screening of surface topographies aiming the regeneration of anisotropically organized tissues such as ligament. The topographies were reproduced in (1) epoxy resin or (2) membranes produced by the crosslinking of platelet lysate (PL) with genipin (gPL). Both materials were seeded with periodontal ligament cells (PDLCs) and the proliferation, migration, as well as cell alignment were assessed. The effect of topography in PDLCs was only evident in terms of cell organization, resulting in a highly anisotropic organization of the cells for the 1000 and 600 nm patterns, and in an increased isotropic organization for shallower topographies. Overall, our results suggest that this multipatterned system can be a valuable diagnostic tool for biomaterials aiming at the regeneration of anisotropically organized tissues, such as periodontal ligament.

Item does not contain fulltext, The composition of calcium phosphate (CaP) ceramics in combination with surface features have been shown to influence biological performance, and micro- and nano-scale topography is known to stimulate osteogenic differentiation of mesenchymal stromal cells (MSCs). In view of this, adipose tissue derived MSCs were cultured on CaP disks featuring hemispherical concavities of various sizes (440, 800 or 1800 mum diameter). It was hypothesized that (i) surface concavities would promote cell proliferation, cellular organization within the concavities, and osteogenic differentiation, as a result of a more pronounced 3D micro-environment and CaP nucleation in concavities, and (ii) MSC proliferation and osteogenic differentiation would increase with smaller concavity size due to more rapidly occurring 3D cell-cell interactions. We found that concavities indeed affect cell proliferation, with 440 mum concavities increasing cell proliferation to a larger extent compared to 800 and 1800 mum concavities as well as planar surfaces. Additionally, concavity size influenced 3D cellular organization within the concavity volume. Interestingly, concavity size promoted osteogenic differentiation of cells, as evidenced by increased osteocalcin gene expression in 440 mum concavities, and osteocalcin staining predominantly for 440 and 800 mum concavities, but not for 1800 mum concavities and only slightly for planar surface controls.

01 februari 2016, Item does not contain fulltext, The current work evaluated the influence of nanoscale surface-topographies in combination with a calcium phosphate (CaP) coating on acellular and cellular surface mineralization. Four groups of substrates were produced, including smooth, grooved (940nm pitch, 430nm groove width, 185nm depth), smooth coated, and grooved coated. The substrates were characterized by scanning/transmission electron microscopy and atomic force microscopy. Osteoblast-like MC3T3 cells were cultured on the substrates for a period up to 35days under osteogenic conditions. Differentiation was observed by alkaline phosphatase assay and PCR of collagen I (COLI), osteopontin (OPN), osteocalcin (OC), bone-morphogenic protein 2 (BMP2), and bone sialoprotein (BSP). Mineralization was quantified by a calcium assay and Alizarin Red staining. In addition, acellular mineralization was determined after incubation of substrates in just cell culture medium without cells. Results showed that a reproducible nano-metric ( approximately 50nm) CaP-layer could be applied on the substrates, without losing the integrity of the topographical features. While no relevant differences were found for cell viability, cells on smooth surfaces proliferated for a longer period than cells on grooved substrates. In addition, differentiation was affected by topographies, as indicated by an increased expression of OC, OPN and ALP activity. Deposition of a CaP coating significantly increased the acellular mineralization of smooth as well grooved substrate-surfaces. However, this mineralizing effect was strongly reduced in the presence of cells. In the cell seeded situation, mineralization was significantly increased by the substrate topography, while only a minor additive effect of the coating was observed. In conclusion, the model presented herein can be exploited for experimental evaluation of cell-surface interaction processes and optimization of bone-anchoring capability of implants. The model showed that substrates modified

Contains fulltext : 167419.pdf (publisher's version ) (Closed access), In the present study, a method was developed to reproduce two nanogrooved patterns (groove width/ridge width/depth: 150/150/50 nm and 200/800/70 nm) into cylindrical epoxy resin implants, which were subsequently coated with 20 nm of titanium. Also, implants with a conventional surface roughness (Rq=1.6 mum) were produced. After cytocompatibility analysis of the produced surfaces, implants were installed into the femoral condyle of rats for 4 and 8 weeks. The histomorphometrical analysis of bone volume in a 100 mum wide zone close to the implant surface showed that only for the 200/800 grooves the amount of bone increased significantly between 4 and 8 weeks of implantation. In addition, at the late time point only implants with the 200/800 pattern revealed a significantly higher bone volume compared to the rough controls. In conclusion, the 200/800 grooved pattern can positively influence bone volume adjacent to the implant surface, and should be evaluated and optimized in further (pre-)clinical studies.

Radboud Universiteit Nijmegen, 26 januari 2016, Promotor : Jansen, J.A. Co-promotor : Walboomers, X.F., Contains fulltext : 150213.pdf (publisher's version ) (Open Access)

Item does not contain fulltext

Item does not contain fulltext, This study investigated whether cells have an intrinsic ability to recognize nanopatterns, which could lead to their accumulation or diminution on a biomaterial. A multi-patterned "biochip" was made, containing 36 differently designed surfaces, including squares and grooves varying in feature sizes between 10 and 1000nm. The grooved patterns could additionally be subdivided into three groups having ridge to groove ratios of 1:1, 1:3 and 3:1. These substrates were used for culture of rat bone marrow derived mesenchymal cells. In time cells should accumulate on patterns of preference, while migrating away from patterns of disfavor. A regression analysis model was designed for the analysis of the obtained data. Results showed that strong differences existed between the tested patterns regarding the cellular affinity. All sizes of squares showed strong cell-repelling capacity, with the biggest sized squares displaying up to 40% less cells compared to the smooth surface. Among the nano-grooved patterns cell repelling was seen for the grooves with the ridge to groove ratio of 1:3, while grooves with the ridge to groove ratio of 3:1 partially showed cell attraction. Such effects were shown to be based on selective migration rather than proliferation. In conclusion, the use of a multi-patterned biochip setup allows for enhanced evaluation of cell behavior, as compared to uniformly patterned setups. Cells exhibit the ability to actively avoid or migrate to surfaces featuring certain topographies on nanometric scale. Such phenomena may be utilized for the development of biomaterials in regenerative medicine.

В России во второй половине XIX в. сформировались школы исследователей, разрабатывавших сибиреязвенные вакцины для нужд сельского хозяйства. По своему уровню они не уступали западным аналогичным школам. В конце 1930-х гг. советские военные ученые впервые в мире создали сибиреязвенную вакцину на основе спор живых бескапсульных штаммов Bacillus anthracis, предназначенную для медицинского применения. Выбранные в 1940–1960-е гг. отечественными учеными направления разработки сибиреязвенных вакцин позволили избежать неудач, с которыми столкнулись западные исследователи, при разработке вакцин, способных защитить население от биологического оружия, использующего в качестве поражающего агента споры возбудителя сибирской язвы. Благодаря усилиям российских военных ученых в 1990-е гг. удалось сохранить вакцинные штаммы сибиреязвенного микроба и восстановить технологические мощности по их производству, что позволяет защитить население Российской Федерации от природных вспышек сибирской язвы и возможных актов биологического терроризма. В условиях, когда необходимо создать у человека иммунитет к ингаляционному заражению спорами возбудителя сибирской язвы, в ближайшие десятилетия наиболее оптимальным будет применение отечественной комбинированной вакцины, сочетающей споры живых бескапсульных штаммов B.anthracis и протективный антиген сибиреязвенного токсина., У Росії у другій половині XIX ст. сформувалися школи дослідників, що розробляють сибіровиразкові вакцини для потреб сільського господарства. За своїм рівнем вони не поступалися західним аналогічним школам. Наприкінці ­1930-х рр. радянські військові вчені вперше у світі створили сибіровиразкову вакцину на основі спор живих безкапсульних штамів Bacillus anthracis, призначену для медичного застосування. Обрані в 1940–1960-ті рр. вітчизняними вченими напрямки розробки сибіровиразкових вакцин дозволили уникнути невдач, з якими зіткнулися західні дослідники, при розробці вакцин, здатних захистити населення від біологічної зброї, що використовує як вражаючий агент спори збудника сибірської виразки. Завдяки зусиллям російських військових вчених в 1990-ті рр. вдалося зберегти вакцинні штами сибіровиразкового мікроба і відновити технологічні потужності щодо їх виробництва, що дозволяє захистити населення Російської Федерації від природних спалахів сибірської виразки і можливих актів біологічного тероризму. В умовах, коли необхідно створити у людини імунітет до інгаляційного зараження спорами збудника сибірської виразки, у найближчі десятиліття найбільш оптимальним буде застосування вітчизняної комбінованої вакцини, яка поєднувала спори живих безкапсульних штамів B.anthracis і протективний антиген сибіровиразкового токсину., In Russia in the second half of the XIX century, research schools developing anthrax vaccines for agriculture were formed. According to their level, they are not inferior to similar Western schools. At the end of the 1930s, Soviet military scientists were the first in the world to create the anthrax vaccine on the basis of the spores of unencapsulated live strains of Bacillus anthracis for medical use. In the 1940–1960s, domestic scientists determined the principles of the development of anthrax vaccines, which enabled to avoid failures of their Western colleagues, when developing the vaccines capable of protecting the population from biological weapons with anthrax spores as the harmful agent. Russian military scientists in the 1990s managed to keep the vaccine strains of anthrax bacteria and to restore the technological capability for their manufacture, which helps to protect the population of the Russian Federation from natural anthrax outbreaks and from biological terror. At a time when there is a need in creating immunity in humans against infection caused by inhalation of anthrax spores, the most reasonable decision for the upcoming decades is to use the domestic combined vaccine that combines unencapsulated live strains of B.anthracis and anthrax toxin protective antigen.

Item does not contain fulltext, Modulation of a materials surface topography can be used to steer various aspects of adherent cell behaviour, such as cell directional organization. Especially nanometric sized topographies, featuring sizes similar to for instance the axons of the spiral ganglion cells, are interesting for such purpose. Here, we utilized nanosized grooves in the range of 75-500 nm, depth of 30-150 nm, and pitches between 150 nm and 1000 nm for cell culture of neuron-like PC12 cells. The organizational behaviour was evaluated after 7 days of culture by bright field and scanning electron microscopy. Nanotopographies were shown to induce aligned cell-body/axon orientation and an increased axonal outgrowth. Our findings suggest that a threshold for cell body alignment of neuronal cells exists on grooved topographies with a groove width of 130 nm, depth of 70 nm and pitch of 300 nm, while axon alignment can already be induced by grooves with 135 nm width, 52 nm depth and 200 nm pitch. However, no threshold has been found for axonal outgrowth, as all of the used patterns increased outgrowth of PC12-axons. In conclusion, surface nanopatterns have the potential to be utilized as an electrode modification for a stronger separation of cells, and can be used to direct cells towards the electrode contacts of cochlear implants.

Item does not contain fulltext

Item does not contain fulltext, This study investigated whether cells have an intrinsic ability to recognize nanopatterns, which could lead to their accumulation or diminution on a biomaterial. A multi-patterned "biochip" was made, containing 36 differently designed surfaces, including squares and grooves varying in feature sizes between 10 and 1000nm. The grooved patterns could additionally be subdivided into three groups having ridge to groove ratios of 1:1, 1:3 and 3:1. These substrates were used for culture of rat bone marrow derived mesenchymal cells. In time cells should accumulate on patterns of preference, while migrating away from patterns of disfavor. A regression analysis model was designed for the analysis of the obtained data. Results showed that strong differences existed between the tested patterns regarding the cellular affinity. All sizes of squares showed strong cell-repelling capacity, with the biggest sized squares displaying up to 40% less cells compared to the smooth surface. Among the nano-grooved patterns cell repelling was seen for the grooves with the ridge to groove ratio of 1:3, while grooves with the ridge to groove ratio of 3:1 partially showed cell attraction. Such effects were shown to be based on selective migration rather than proliferation. In conclusion, the use of a multi-patterned biochip setup allows for enhanced evaluation of cell behavior, as compared to uniformly patterned setups. Cells exhibit the ability to actively avoid or migrate to surfaces featuring certain topographies on nanometric scale. Such phenomena may be utilized for the development of biomaterials in regenerative medicine.

Item does not contain fulltext, Modulation of a materials surface topography can be used to steer various aspects of adherent cell behaviour, such as cell directional organization. Especially nanometric sized topographies, featuring sizes similar to for instance the axons of the spiral ganglion cells, are interesting for such purpose. Here, we utilized nanosized grooves in the range of 75-500 nm, depth of 30-150 nm, and pitches between 150 nm and 1000 nm for cell culture of neuron-like PC12 cells. The organizational behaviour was evaluated after 7 days of culture by bright field and scanning electron microscopy. Nanotopographies were shown to induce aligned cell-body/axon orientation and an increased axonal outgrowth. Our findings suggest that a threshold for cell body alignment of neuronal cells exists on grooved topographies with a groove width of 130 nm, depth of 70 nm and pitch of 300 nm, while axon alignment can already be induced by grooves with 135 nm width, 52 nm depth and 200 nm pitch. However, no threshold has been found for axonal outgrowth, as all of the used patterns increased outgrowth of PC12-axons. In conclusion, surface nanopatterns have the potential to be utilized as an electrode modification for a stronger separation of cells, and can be used to direct cells towards the electrode contacts of cochlear implants.

Item does not contain fulltext, Modulation of a materials surface topography can be used to steer various aspects of adherent cell behaviour, such as cell directional organization. Especially nanometric sized topographies, featuring sizes similar to for instance the axons of the spiral ganglion cells, are interesting for such purpose. Here, we utilized nanosized grooves in the range of 75-500 nm, depth of 30-150 nm, and pitches between 150 nm and 1000 nm for cell culture of neuron-like PC12 cells. The organizational behaviour was evaluated after 7 days of culture by bright field and scanning electron microscopy. Nanotopographies were shown to induce aligned cell-body/axon orientation and an increased axonal outgrowth. Our findings suggest that a threshold for cell body alignment of neuronal cells exists on grooved topographies with a groove width of 130 nm, depth of 70 nm and pitch of 300 nm, while axon alignment can already be induced by grooves with 135 nm width, 52 nm depth and 200 nm pitch. However, no threshold has been found for axonal outgrowth, as all of the used patterns increased outgrowth of PC12-axons. In conclusion, surface nanopatterns have the potential to be utilized as an electrode modification for a stronger separation of cells, and can be used to direct cells towards the electrode contacts of cochlear implants.

Item does not contain fulltext

Item does not contain fulltext, The search for alternative therapies to improve bone regeneration continues to be a major challenge for the medical community. Here we report on the enhanced mineralization, osteogenesis, and in vivo bone regeneration properties of a bioactive elastin-like recombinamer (ELR) membrane. Three bioactive ELRs exhibiting epitopes designed to promote mesenchymal stem cell adhesion (RGDS), mineralization (DDDEEKFLRRIGRFG), and both cell adhesion and mineralization were synthesized using standard recombinant protein techniques. The ELR materials were then used to fabricate membranes comprising either a smooth surface (Smooth) or channel microtopographies (Channels). Mineralization and osteoblastic differentiation of primary rat mesenchymal stem cells (rMSCs) were analyzed in both static and dynamic (uniaxial strain of 8% at 1 Hz frequency) conditions. Smooth mineralization membranes in static condition exhibited the highest quantity of calcium phosphate (Ca/P of 1.78) deposition with and without the presence of cells, the highest Young's modulus, and the highest production of alkaline phosphatase on day 10 in the presence of cells growing in non-osteogenic differentiation medium. These membranes were tested in a 5 mm-diameter critical-size rat calvarial defect model and analyzed for bone formation on day 36 after implantation. Animals treated with the mineralization membranes exhibited the highest bone volume within the defect as measured by micro-computed tomography and histology with no significant increase in inflammation. This study demonstrates the possibility of using bioactive ELR membranes for bone regeneration applications.

Contains fulltext : 136701.pdf (publisher's version ) (Open Access), Mitochondrial DNA (mtDNA) is organized in discrete protein-DNA complexes, nucleoids, that are usually considered to be mitochondrial-inner-membrane associated. Here we addressed the association of replication factors with nucleoids and show that endogenous mtDNA helicase Twinkle and single-stranded DNA-binding protein, mtSSB, co-localize only with a subset of nucleoids. Using nucleotide analogs to identify replicating mtDNA in situ, the fraction of label-positive nucleoids that is Twinkle/mtSSB positive, is highest with the shortest labeling-pulse. In addition, the recruitment of mtSSB is shown to be Twinkle dependent. These proteins thus transiently associate with mtDNA in an ordered manner to facilitate replication. To understand the nature of mtDNA replication complexes, we examined nucleoid protein membrane association and show that endogenous Twinkle is firmly membrane associated even in the absence of mtDNA, whereas mtSSB and other nucleoid-associated proteins are found in both membrane-bound and soluble fractions. Likewise, a substantial amount of mtDNA is found as soluble or loosely membrane bound. We show that, by manipulation of Twinkle levels, mtDNA membrane association is partially dependent on Twinkle. Our results thus show that Twinkle recruits or is assembled with mtDNA at the inner membrane to form a replication platform and amount to the first clear demonstration that nucleoids are dynamic both in composition and concurrent activity.

Producción Científica, In the field of tissue engineering, the properties of the scaffolds are of crucial importance for the success of the application. Hybrid materials combine properties of the different components that constitute them. In this study hybrid gels of elastin-like recombinamer (ELR) and fibrin were prepared with a range on polymer concentrations and ELR-to-fibrin ratios. The correlation between SEM micrographs, porosity, swelling ratio and rheological properties was discussed and a poroelastic mechanism was suggested to explain the mechanical behavior of the hybrid gels. Applicability as scaffold material for cardiovascular tissue engineering was shown by the realization of cell-laden matrixes which supported the synthesis of collagens as revealed by immunohistochemical analysis. As a proof of concept, a tissue-engineered heart valve was fabricated by injection moulding and cultivated in a bioreactor for 3 weeks under dynamic conditions. Tissue analysis revealed production of collagen I and III, fundamental proteins for cardiovascular constructs., Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA244U13)

Contains fulltext : 136701.pdf (publisher's version ) (Open Access), Mitochondrial DNA (mtDNA) is organized in discrete protein-DNA complexes, nucleoids, that are usually considered to be mitochondrial-inner-membrane associated. Here we addressed the association of replication factors with nucleoids and show that endogenous mtDNA helicase Twinkle and single-stranded DNA-binding protein, mtSSB, co-localize only with a subset of nucleoids. Using nucleotide analogs to identify replicating mtDNA in situ, the fraction of label-positive nucleoids that is Twinkle/mtSSB positive, is highest with the shortest labeling-pulse. In addition, the recruitment of mtSSB is shown to be Twinkle dependent. These proteins thus transiently associate with mtDNA in an ordered manner to facilitate replication. To understand the nature of mtDNA replication complexes, we examined nucleoid protein membrane association and show that endogenous Twinkle is firmly membrane associated even in the absence of mtDNA, whereas mtSSB and other nucleoid-associated proteins are found in both membrane-bound and soluble fractions. Likewise, a substantial amount of mtDNA is found as soluble or loosely membrane bound. We show that, by manipulation of Twinkle levels, mtDNA membrane association is partially dependent on Twinkle. Our results thus show that Twinkle recruits or is assembled with mtDNA at the inner membrane to form a replication platform and amount to the first clear demonstration that nucleoids are dynamic both in composition and concurrent activity.

Item does not contain fulltext, The search for alternative therapies to improve bone regeneration continues to be a major challenge for the medical community. Here we report on the enhanced mineralization, osteogenesis, and in vivo bone regeneration properties of a bioactive elastin-like recombinamer (ELR) membrane. Three bioactive ELRs exhibiting epitopes designed to promote mesenchymal stem cell adhesion (RGDS), mineralization (DDDEEKFLRRIGRFG), and both cell adhesion and mineralization were synthesized using standard recombinant protein techniques. The ELR materials were then used to fabricate membranes comprising either a smooth surface (Smooth) or channel microtopographies (Channels). Mineralization and osteoblastic differentiation of primary rat mesenchymal stem cells (rMSCs) were analyzed in both static and dynamic (uniaxial strain of 8% at 1 Hz frequency) conditions. Smooth mineralization membranes in static condition exhibited the highest quantity of calcium phosphate (Ca/P of 1.78) deposition with and without the presence of cells, the highest Young's modulus, and the highest production of alkaline phosphatase on day 10 in the presence of cells growing in non-osteogenic differentiation medium. These membranes were tested in a 5 mm-diameter critical-size rat calvarial defect model and analyzed for bone formation on day 36 after implantation. Animals treated with the mineralization membranes exhibited the highest bone volume within the defect as measured by micro-computed tomography and histology with no significant increase in inflammation. This study demonstrates the possibility of using bioactive ELR membranes for bone regeneration applications.

Producción Científica, In the field of tissue engineering, the properties of the scaffolds are of crucial importance for the success of the application. Hybrid materials combine properties of the different components that constitute them. In this study hybrid gels of elastin-like recombinamer (ELR) and fibrin were prepared with a range on polymer concentrations and ELR-to-fibrin ratios. The correlation between SEM micrographs, porosity, swelling ratio and rheological properties was discussed and a poroelastic mechanism was suggested to explain the mechanical behavior of the hybrid gels. Applicability as scaffold material for cardiovascular tissue engineering was shown by the realization of cell-laden matrixes which supported the synthesis of collagens as revealed by immunohistochemical analysis. As a proof of concept, a tissue-engineered heart valve was fabricated by injection moulding and cultivated in a bioreactor for 3 weeks under dynamic conditions. Tissue analysis revealed production of collagen I and III, fundamental proteins for cardiovascular constructs., Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA244U13)