1. Uporaba nanotomografijev biomedicinski znanosti in mediciniJernej Vajda, Marko Milojević, Uroš Maver, Boštjan Vihar, 2025, review article Keywords: Computed tomography, CT, Microtomography, Micro-CT, Nanotomography, Nano-CT, Biomedical imaging
Published in DKUM: 30.07.2025; Views: 0; Downloads: 7
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2. Substrate-dependent variability in viability and angiogenicmarker expression among three endothelial cell subtypes : insights for artificial tissue vascularizationJernej Vajda, Boštjan Vihar, Marko Milojević, Dragana Bjelić, Amadeja Brečko, Uroš Maver, 2025, original scientific article Abstract: issue engineering faces the challenge of achieving effective vascularization within tissue constructs for sustained viability andoptimal function. The success of tissue-engineered constructs depends on selecting an optimal angiogenesis-stimulating ECMsubstitute material. This study compares four substrates made from three different biomacromolecules—fibrin, fibronectin,non-crosslinked, and crosslinked gelatin, and their effect on endothelial cells. Acknowledging the diverse range of endothelialcells that play a role in (micro)vascularization, human endothelial primary cells, human umbilical vein endothelial cells, andhuman microvascular endothelial cells are subjected to these materials for evaluation. Biocompatibility is assessed by measuringcell viability (Live/Dead assay), metabolic activity (alamarBlue assay), morphology (actin staining), phenotype expression(immunocytochemistry), and the production of von Willebrand factor, which promotes angiogenesis by promoting cell adhesionand migration. The results show that the use of biomaterials as culturing substrates significantly impacts the viability andmorphology of the cells. While the expression of angiogenic markers is shown to rely more on the cell lineage, the use of differentsubstrates has an impact on the expression timeline. Thus, combining cells and biomaterials in a favorable manner can be usedas a powerful tool for controlled vascularization in vitro, which requires the systematic assembly of different stimuli.
Keywords: biomacromolecules, endothelial cell types, materials, microvascularization, vascularization
Published in DKUM: 22.07.2025; Views: 0; Downloads: 3
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3. Razvoj novih metod izdelave in karakterizacije mikrožilja v in vitro modelihJernej Vajda, 2025, doctoral dissertation Abstract: Doktorska disertacija obravnava optimizacijo postopkov, materialov in analiznih metod v tkivnem inženirstvu mikrožilja z multidisciplinarnim pristopom, ki poleg uveljavljenih bioloških in kemijskih metod vključuje tudi računalniške simulacije, mehanske teste in nanotomografijo. V okviru raziskovalnega dela smo optimizirali linearnost ekstruzije mehanskih ekstruzijskih 3D tiskalnikov, s čimer smo dosegli boljše in bolj ponovljive rezultate 3D (bio)tiska vzorcev. Pri natisnjenih vzorcih smo primerjali uporabo CaCl2 in SrCl₂ kot ionskih zamreževalcev, pri čemer se je izkazalo, da je uporaba SrCl2 ob primerljivi celični metabolni aktivnosti izboljšala mehanske lastnosti materialov, kombinacija Sr²⁺ in Ca²⁺ pa bi lahko omogočala dodatno prilagoditev mehanskih lastnosti materialov. Uporaba Sr²⁺ hkrati zmanjša tudi vpliv kalcijevih ionov na signalizacijo celic, kar je ključno za simuliranje biološkega okolja. Na drugi strani smo s simulacijami računalniške dinamike tekočin določili mejne pogoje za razvoj peristaltične črpalke,
s katero smo eksperimentalno ovrednotili vpliv strižnih napetosti na endotelijske celice in validirali simulirane rezultate. Ločeno smo na endotelijskih celicah iz različnih virov in na podpornih celicah – kožnih fibroblastih – preiskovali lastnosti materialov in njihov vpliv na viabilnost, ohranitev celičnega fenotipa in funkcionalnosti ter celokupno metabolno aktivnost. Rezultati študij potrjujejo, da je z natančno optimizacijo procesov in materialov mogoče izboljšati funkcionalnost tkivnih in vitro modelov, kar odpira nove možnosti za napredek v tkivnem inženirstvu in regenerativni medicini.
Keywords: mikrožilje, in vitro model, 3D tisk, računalniška dinamika tekočin, nanotomografija
Published in DKUM: 04.07.2025; Views: 0; Downloads: 25
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4. Quasi-static and impact behaviour of polymer-metal interpenetrating phase TPMS compositesNejc Novak, Oraib Al-Ketan, Anja Mauko, Lovre Krstulović-Opara, Shigeru Tanaka, Matej Borovinšek, Boštjan Vihar, Uroš Maver, Kazuyuki Hokamoto, Matej Vesenjak, Zoran Ren, 2025, original scientific article Abstract: Interpenetrating phase composites (IPC) are materials with two or more mutually continuous, interconnected phases. This structure allows each phase to retain its properties, while together they exhibit enhanced synergistic properties. In this work, polymer-metal IPCs with Triply Periodical Minimal Surface (TPMS) structures were fabricated and tested for their mechanical properties at different impact velocities (ranging from 0.1 mm/s to 250 m/s). Samples. The samples comprise a stainless steel reinforcement phase and two polymeric matrices (silicone and epoxy). Computed tomography was used to evaluate the internal structure and the fabrication quality. The results showed that the samples were thoroughly infiltrated with polymeric filler, achieving a high degree of homogeneity in the composite. The compression tests of silicone-filled IPCs showed an increase in stiffness. Still, the Specific Energy Absorption (SEA) was not improved due to the non-optimal stiffness ratio between the polymeric matrix and the metallic reinforcement phase. However, using epoxy as the matrix resulted in the SEA enhancement of 38 %. This is attributed to the interlocking mechanism between the two phases, which improved the macroscopic mechanical properties. The compression tests showed significant strain rate hardening due to the base material’s strain rate sensitivity and the inertia effects.
Keywords: TPMS, interpenetrating phase composite, polymer filler, hybrid structure, experimental testing, mechanical properties, strain rate effect
Published in DKUM: 26.05.2025; Views: 0; Downloads: 14
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5. Solidification of gelatine hydrogels by using a cryoplatform and its validation through CFD approachesYasir Beeran Potta Thara, Miha Jordan, Timi Gomboc, Blaž Kamenik, Boštjan Vihar, Vanja Kokol, Matej Zadravec, 2022, original scientific article Abstract: In this work, we developed a numerical approach based on an experimental platform
to determine the working conditions on a cryoplatform and to predict and evaluate the cryogenic
printing of hydrogels. Although hydrogels have good biocompatibility, their material properties
make it difficult to print them with high precision and shape fidelity. To overcome these problems, a
cryogenic cooling platform was introduced to accelerate the physical stabilisation of each deposited
layer during the printing process. By precisely controlling solidification (crystallisation), each printed
material can withstand its own weight to maintain shape fidelity, and the porosity of the scaffolds
can also be controlled more selectively. The thermophysical properties of gelatine hydrogels were
investigated to gain a better understanding of the phase change upon freezing. The corresponding
material properties and experimental observations of gelatine solidification served as the basis for
developing a computational fluid model (CFD) to mimic the solidification of gelatine hydrogels
using a cryoplatform at different process conditions and extruder speeds. The goal was to develop a
tool simple enough to predict acceptable process conditions for printing gelatine hydrogels using
a cryoplatform.
Keywords: gelatine, hydrogel, cryoprinting, CFD simulation, solidification modelling
Published in DKUM: 20.03.2025; Views: 0; Downloads: 12
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6. Nanodelci hitozana kot potencialni protimikrobni premazZdenka Peršin Fratnik, Uroš Maver, Metod Kolar, Olivera Šauperl, Lidija Fras Zemljič, Boštjan Vihar, 2024, original scientific article Abstract: Namen študije je bil ugotoviti protimikrobno učinkovitost hitozanskih nanodelcev v primerjavi s hitozansko raztopino in sled temu njihovo učinkovito rabo na medicinskih tekstilnih materialih.
Keywords: chitosan, nanoparticles, antimicrobial activity, coatings, medical textile materials
Published in DKUM: 07.01.2025; Views: 0; Downloads: 25
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7. Kratek pregled platform za ADME testiranjeTina Maver, Boštjan Vihar, Uroš Maver, 2024, original scientific article Abstract: V zadnjem času je bil dosežen pomemben napredek pri razvoju ADME (absorpcija, distribucija, metabolizem, ekskrecija) modelov, vendar izziv ostaja vzpostaviti platforme, ki bi zmanjšale testiranje na živalih in stroške raziskav. Naraščajoča pomembnost farmakokinetičnih interakcij poudarja potrebo po zanesljivih in
ponovljivih ADME modelih, ki so vse bolj ključni za razvoj zdravil in zagotavljanje varnosti z željo po preprečevanju
resnih kliničnih zapletov in hospitalizacije.
Keywords: ADME, drug interaction studies, in vitro models, pharmacokinetics, multi-organ models
Published in DKUM: 07.01.2025; Views: 0; Downloads: 26
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8. Mesenchymal stem cells isolated from paediatric paravertebral adipose tissue show strong osteogenic potentialJan Rožanc, Lidija Gradišnik, Tomaž Velnar, Minja Gregorič, Marko Milojević, Boštjan Vihar, Boris Gole, Uroš Maver, 2022, original scientific article Abstract: Mesenchymal stem cells (MSCs) represent the basis of novel clinical concepts in cellular therapy and tissue regeneration. Therefore, the isolation of MSCs from various tissues has become an important endeavour for stem cell biobanking and the development of regenerative therapies. Paravertebral adipose tissue is readily exposed during spinal procedures in children and could be a viable source of stem cells for therapeutic applications. Here, we describe the first case of MSCs isolated from paravertebral adipose tissue (PV-ADMSCs), obtained during a routine spinal surgery on a child. Using quantitative real-time PCR and flow cytometry, we show that PV-ADMSCs have different levels of stem marker expression compared to the MSCs from other sources while having the highest proliferation rate. Furthermore, we evaluate the multipotency of PV-ADMSCs by the three-lineage (adipogenic, osteogenic and chondrogenic) differentiation and compare it to the multipotency of MSCs from other sources. It was found that the PV-ADMSCs have a strong osteogenic potential in particular. Taken together, our data indicate that PV-ADMSCs meet the criteria for successful cell therapy, defined by the International Society for Cellular Therapy (ISCT), and thus, could provide a source of MSCs that is relatively easy to isolate and expand in culture. Due to their strong osteogenic potential, these cells provide a promising basis, especially for orthopaedic applications.
Keywords: mesenchymal stem cells, paediatric surgery, paravertebral adipose tissue, regenerative medicine, stem marker expression, osteogenic potential, differentiation
Published in DKUM: 16.12.2024; Views: 0; Downloads: 13
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9. Investigating the viability of epithelial cells on polymer based thin-filmsBoštjan Vihar, Jan Rožanc, Boštjan Krajnc, Lidija Gradišnik, Marko Milojević, Laura Činč Ćurić, Uroš Maver, 2021, original scientific article Abstract: The development of novel polymer-based materials opens up possibilities for several novel applications, such as advanced wound dressings, bioinks for 3D biofabrication, drug delivery systems, etc. The aim of this study was to evaluate the viability of vascular and intestinal epithelial cells on different polymers as a selection procedure for more advanced cell-polymer applications. In addition, possible correlations between increased cell viability and material properties were investigated. Twelve polymers were selected, and thin films were prepared by dissolution and spin coating on silicon wafers. The prepared thin films were structurally characterized by Fourier transform infrared spectroscopy, atomic force microscopy, and goniometry. Their biocompatibility was determined using two epithelial cell lines (human umbilical vein endothelial cells and human intestinal epithelial cells), assessing the metabolic activity, cell density, and morphology. The tested cell lines showed different preferences regarding the culture substrate. No clear correlation was found between viability and individual substrate characteristics, suggesting that complex synergistic effects may play an important role in substrate design. These results show that a systematic approach is required to compare the biocompatibility of simple cell culture substrates as well as more complex applications (e.g., bioinks).
Keywords: HUIEC, HUVEC, morphology, polymers, thin films, viability
Published in DKUM: 18.10.2024; Views: 0; Downloads: 9
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10. Microvascular tissue engineering : a reviewJernej Vajda, Marko Milojević, Uroš Maver, Boštjan Vihar, 2021, review article Abstract: Tissue engineering and regenerative medicine have come a long way in recent decades, but the lack of functioning vasculature is still a major obstacle preventing the development of thicker, physiologically relevant tissue constructs. A large part of this obstacle lies in the development of the vessels on a microscale%the microvasculature%that are crucial for oxygen and nutrient delivery. In this review, we present the state of the art in the field of microvascular tissue engineering and demonstrate the challenges for future research in various sections of the field. Finally, we illustrate the potential strategies for addressing some of those challenges.
Keywords: regenerative medicine, tissue engineering, vascularization, biomaterials, microvascularization, coculture, gradients
Published in DKUM: 18.10.2024; Views: 0; Downloads: 13
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