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TERMIS 2023 – European Chapter Manchester Central Conference Centre Manchester, UK March 28–31, 2023

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10.1089/ten.tea.2023.29043.abstracts

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Diabetic Foot Ulcer Assessment and Management

Tissue Engineering Part AAhead of Print AbstractsFree AccessTERMIS 2023 – European Chapter Manchester Central Conference Centre Manchester, UK March 28–31, 2023Published Online:30 Jun 2023https://doi.org/10.1089/ten.tea.2023.29043.abstractsAboutSectionsPDF/EPUB Permissions & CitationsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail ORAL PRESENTATIONs' ABSTRACTSOP‐001 Sustainable Biomaterials of bacterial origin and their use in Biomedical ApplicationsIpsita RoyDepartment of Materials Science and Engineering, Faculty of Engineering, University of Sheffield, Sheffield, UKINTRODUCTION: There is a huge need to find replacements for petrochemical‐derived plastics which are not sustainable, degradable and lead to high concentrations of recalcitrant plastics in the soil and the sea. In the medical arena, there is not much attention paid to the sustainability of the materials used. In this work we have focused on the production and use of bacteria‐derived sustainable biomaterials for use in biomedical applications.Two main types of biomaterials have been focused on, including polyhydroxyalkanoates, PHAs,(1) and bacterial cellulose, BC, (2). PHAs are polyesters produced by a range of bacteria that are biodegradable in the soil and sea and are also resorbable in the human body and highly biocompatible. BC is also be produced by a range of bacteria, is a sustainable green polymer, degradable in the soil, highly biocompatible. Hence, both PHAs and BC can be used for biomedical applications.METHODS: Poly(3‐hydroxybutyrate), P(3HB), a stiff scl‐PHA was produced using Burkholderia sp and an elastomeric mcl‐PHA was produced using Pseudomonas sp., at 30L scale using the fed batch mode. The polymers were characterised with respect to mechanical and thermal properties and processed using gyro spinning, electrospinning and Fused deposition modelling (FDM), melt electrowriting and dip moulding. The constructs were subjected to in vitro and in vivo biocompatibility analysis. Bacterial cellulose was produced under static culture conditions using G. xylinus.RESULTS: P(3HB), its blends and composites were used for bone tissue engineering, drug delivery, coronary artery stents and nerve tissue repair. The mcl‐PHA was used for the development of cardiac patches, nerve guidance conduits, wound healing patch, bioartificial pancreas and bioartificial kidney. In all cases the results were extremely positive both from a mechanical and functional context, in vitro and in vivo.The BC was a highly nano‐fibrillated and was surface modified to create antibacterial bacterial cellulose. BC was also used as a filler for P(3HB) based composites.DISCUSSION & CONCLUSIONS: In conclusion, we successfully produced and used bacteria‐derived sustainable biomaterials for a variety of biomedical applications, including hard and soft tissue engineering. Both PHAs and bacterial cellulose have a lot of potential in the future as sustainable materials of choice.ACKNOWLEDGEMENTS: The author acknowledges funding from the EPSRC, EU (FP7, Horizon 2020), Marie Curie EID scheme, BHF and British Council ICRG‐2020 grant,Project No 105.REFERENCES: 1. Basnett et al., 2021, ACS Applied Materials Interfaces, 13, 28, 32624–32639,2. Gregory et al., 2022 Materials Science and Engineering R, 145(2017):100623Keywords: Biomaterials, Composite materialsOP‐002 Fibrin and silk fibroin as complementary materials of biocomposites for tissue engineeringIkram El Maachi1, Stavroula Kyriakou1, Stephan Rütten2, Alexander Alexander Kopp3, Stefan Jockenhoevel1, Alicia Fernández‐Colino11Department of Biohybrid & Medical Textiles (BioTex), AME‐Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, D‐52074 Aachen, Germany2Electron Microscopy Facility, Uniklinik RWTH Aachen, D‐52074 Aachen, Germany3Fibrothelium GmbH, D‐52068 Aachen, GermanyINTRODUCTION: In the context of tissue engineering, a single material often fall short of meeting all the necessary requirements to obtain a fully functional substitute for native tissue [1]. For instance, fibrin is known as a natural polymer with an excellent bioactivity, versatility and processability [2], but restricted in the biomedical applications by its cell‐mediated contraction and insufficient mechanical strength [3]. In this work, we overcome these drawbacks by combining fibrin with another extraordinary natural polymer, silk fibroin, with a simple and reproducible biofabrication approach [4].METHODS: The fabrication of fibrin and silk fibroin composites was carried out by injection‐molding. The internal structure of the resulting scaffolds was investigated by scanning electron microscopy. The mechanical properties were characterized by rheology and burst strength. The fibrin/silk fibroin scaffolds were seeded with primary cells, such as human venous endothelial cells (HUVECs) and human arterial smooth muscle cells (HUASMCs), to test respectively the bioactivity and the resistance to the cell‐mediated contraction. Confocal microscopy was used to analyze the cell adhesion and morphology. The feasibility to fabricate composite scaffolds of a tubular shape was also explored.RESULTS: Homogenous, porous and reproducible composite scaffolds of fibrin/ silk fibroin were obtained by adopting injection‐molding approach. The developed composites featured significantly higher mechanical properties than those made of only fibrin. The cellular studies showed a formation of confluent and adherent endothelial cell layer and minimal cell‐mediated contraction. We demonstrate the feasibility to fabricate composite scaffold with a tubular shape, which could be bended 180 ° without kinking, speaking for outstanding flexibility.DISCUSSION & CONCLUSIONS: With a simple and scalable biofabrication approach, we obtained composite scaffolds, characterized by synergy between complementary components, i.e., fibrin's exceptional bioactivity was combined with the mechanical stability offered by silk fibroin. The flexibility together with the versatility to mold into different shapes make the developed composite scaffolds promising candidates for cardiovascular tissue engineering applications.ACKNOWLEDGEMENTS: The authors acknowledge the NanoMatFutur Program of the German Ministry of Education and Research (BMBF, grant number 13XP5136).REFERENCES: 1. Sell, S.A.; et al. Polymers, 2010.2. Brown, A.C.; et al. Acta Biomaterialia, 2014.3. Jockenhoevel, S.; et al. European journal of cardio‐thoracic surgery: official journal of the European Association for Cardio‐thoracic Surgery, 2001.4. El Maachi, I.; et al. Polymers (Basel), 2022.Keywords: Composite materials,OP‐003 Growth Factor delivery through electrospun microfibres for tendon regenerationVera Citro1, Aldo R. Boccaccini2, Nicholas R. Forsyth11School of Pharmacy & Bioengineering, Keele University, Stoke on Trent, England2Institute of Biomaterials, University of Erlangen‐Nuremberg FAU, Erlangen, GermanyINTRODUCTION: Proliferation and differentiation towards particular lineages can be regulated by signalling from cells and the niche they inhabit. For example, Mesenchymal Stromal Cell (MSCs) fate is influenced by soluble biochemical factors, including growth factors, and also by biophysical cues provided by co‐localised extracellular matrix arrangement and surrounding mechanical forces. To address the inherent limitations of supra‐physiological dosage administration to drive specific phenotypes and derive optimal release kinetics, biomaterial‐based approaches have emerged as a powerful tool. These approaches can be tailored to modulate proliferation, self‐renewal, and tenogenesis of MSCs, drawing on the synergy between stimuli that incorporate a combination of molecules, such as growth factors, released in a controlled manner in a three‐dimensional mechanically supportive scaffold.METHODS: Three different growth factors (GDF5/6/7) have been analysed individually to assess their tenoinductive potential on MSCs. The synergic effect of growth factors and physoxia are investigated as major factors that recapitulate the tendon developmental processes. Tenomodulin immunofluorescence and RT‐qPCR techniques have been performed in parallel on hBM‐MSCs and TSCs, to assess the expression of tendon‐linked transcripts Scx, Tnmd, Tnc‐C and Thromb4. To recreate the level of complexity stemming from biophysical, biochemical, and biological cues of native tendon niches, hierarchical anisotropic structure directing 3D cellular orientation were produced. PCL micro and nano electrospun fibres have been evaluated to explore their role in TSCs differentiation in growth factor supplemented media.RESULTS: We demonstrated that MSCs tenomodulin expression was improved by GDF7 up to 134% with respect to control in 21%O2 and up to 78% in 2%O2. In TSCs, instead, we noticed that physoxia, independently from any other exogenous stimuli, can preserve the tenocyte's phenotypic profile. ‘Green’ electrospun scaffolds with micron range fibres maintained tenocytes phenotype, alignment and elongation. Further, TSCs seeded on 1 ± 0.4 μm fibres displayed increased extracellular matrix deposition.DISCUSSION & CONCLUSIONS: Tendon tissue engineering aims to provide autograft alternatives in providing a biocompatible scaffold for cell and tissue remodelling in vivo. Implementing three dimensional scaffolds aids in guiding and controlling cell orientation, ultimately enabling anisotropic tissues in vitro. Engineering artificial platforms intended to sustain tissue production in vitro must take into account the dynamic structural and compositional changes of the system. The array of signal embossed on the material surface constitutes the initial condition from which cell‐cell and cell‐matrix interactions establish and guide the evolution of the entire array of signals.Keywords: Biomechanics / biophysical stimuli and mechanotransduction, Drug deliveryOP‐004 Proteomic analysis of doped sol‐gel coatings: correlation betweenin vitroandin vivobiological responsesIñaki García Arnáez1, Francisco Romero Gavilán2, Andreia Cerqueira2, Felix Elortza3, Mikel Azkargorta3, Fernando Muñoz4, Manuel Mata5, José Javier Martín De Llano5, Julio Suay2, Mariló Gurruchaga1, Isabel Goñi11Department of Polymers and Advanced Materials: Physics, Chemistry and Technology, University of the Basque Country (UPV/EHU), San Sebastián, Spain2Department of Industrial Systems Engineering and Design, Universitat Jaume I, Castellón de la Plana, Spain3Proteomics Platform, CIC bioGUNE, Derio, Spain4Department of Veterinary Clinical Sciences. Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain & iBoneLab SL, Lugo, Spain5Department of Pathology Medicine and Odontology, Medicine Faculty, University of Valencia, Valencia, Spain & Research Institute of the University Clinical Hospital of Valencia (INCLIVA), Valencia, SpainINTRODUCTION: Poor correlation between the results of in vitro testing and the subsequent in vivo experiments hinders the design of biomaterials. Thus, new characterisation methods are needed. This study used proteomic and histological techniques to analyse the effects of Ca‐doped biomaterials in vitro and in vivo and verify the correlation between the two systems.METHODS: The acid catalysis sol‐gel route was employed to synthetise the different coatings, from the combination of MTMOS and TEOS alkoxysilane precursors. This material was functionalised with 0.5 and 5 wt% of CaCl2. Ti discs and custom‐made implants were coated with prepared materials by dip‐coating. Morphology of the coatings was examined using SEM; the Ca2+ ion release from the materials was analysed by means of ICP‐AES spectroscopy. The osteogenic and inflammatory responses were inspected in vitro inhuman osteoblasts (HOb) and TPH‐1 monocytes. The in vivo experiments used a rabbit model. The nLC‐MS/MS‐based proteomic methods were utilised to analyse the proteins adhering to the material samples incubated with human serum or examine protein expression in the tissues close to the implants.RESULTS: Ca‐doped biomaterials caused a remarkable increase in the adsorption of coagulation‐related proteins, both in vitro (PLMN, THRB, FIBA and VTNC) and in vivo (FBLN1, G1U978). Enhanced affinity to these materials was also observed for proteins involved in inflammation (CO5, C4BPA, IGHM and KV302 in vitro; CARD6, DDOST and CD14 in vivo) and osteogenic functions (TETN, PEDF in vitro; FBN1, AHSG, MYOC in vivo).DISCUSSION & CONCLUSIONS: The results obtained using different techniques were well matched, with a good correlation between the in vitro and in vivo experiments. Thus, the proteomic analysis of biological responses to biomaterials in vitro is a useful tool for predicting their impact in vivo.ACKNOWLEDGEMENTS: This work was supported by Ministerio de Ciencia e Innovación (PID2020‐113092RB‐C21), University of the Basque Country UPV/EHU (MARSA21/07), Basque Government (PRE_2016_1_0141), Universitat Jaume I (UJI‐B2021‐25) and Generalitat Valenciana (APOSTD/2020/036, PROMETEO/2020/069). The authors would like to thank for technical and staff support provided by SGIker (UPV/EHU/ ERDF, EU), and the company GMI Dental Implantology SL for producing the titanium discs and implants.Keywords: Bone and bone disorders (osteoporosis etc), Omics / bioinformatics and systems biologyOP‐005 Endotoxin Removal from Chitosan Produces Biocompatible Chitosan‐Genipin HydrogelsEmma Jackson1, Sophie Reay2, Dan Salthouse2, Ana Ferreira Duarte2, Katarina Novakovic2, Catharien Hilkens11Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK2School of Engineering, Newcastle University, Newcastle upon Tyne, UKINTRODUCTION: Chitosan‐based biomaterials are becoming increasingly popular for biomedical applications including wound healing, drug delivery and tissue regeneration. As chitosan is naturally derived, it is susceptible to endotoxin contamination. Bacterial endotoxins elicit potent proinflammatory responses in vivo, therefore, it is critical that endotoxin is quantified and removed from any biomaterial intended for in vivo use. In the presented work, heat‐treatment (180°C for 1.5 hours) and sodium hydroxide‐treatment (1M for 2 hours) are investigated as two endotoxin removal methods from chitosan. While endotoxin removal is the prime task, it is important to note that preservation of chitosan structure is vital for synthesis and in vivo lysozyme degradation of chitosan‐based hydrogels.METHODS: The limulus amebocyte lysate (LAL) assay was used to quantify the endotoxin content of chitosan samples. Endotoxin removal was also assessed by measuring TNF‐alpha production from PBMCs cultured with treated or native chitosan. FTIR was employed to determine the effect of endotoxin removal methods on chitosan structure. Chitosan‐genipin hydrogels were synthesized and lysozyme degradation was investigated gravimetrically. Hydrogels were co‐cultured separately with immature monocyte‐derived DCs (moDCs) and cell viability and expression of maturation markers (CD83, CD86 and PDL‐1) expression was assessed by flow cytometry.RESULTS: Both heat and NaOH treatment significantly reduced the endotoxin level compared to native chitosan, to concentrations below the FDA limit for medical devices (0.5 EU/ml). NaOH‐treatment significantly reduced TNF‐alpha secretion by PBMCs compared to native chitosan; however, the difference was non‐significant for the heat‐treated chitosan, which was excluded from further testing. Although the FTIR spectra of native and NaOH‐treated chitosan were extremely similar, NaOH treatment reduced the degree of acetylation of native chitosan by 6%. As lysozyme only interacts with the acetylated units of chitosan, it was important to determine if NaOH‐treated chitosan is susceptible to lysozyme degradation. Chitosan‐genipin hydrogels were synthesized and gravimetric degradation studies using lysozyme showed that hydrogels composed of native and NaOH‐treated chitosan had comparable degradation rates. NaOH‐treated chitosan did not negatively affect viability of immature DCs, furthermore the expression of maturation markers was non‐significant between NaOH chitosan‐genipin hydrogel condition and the immature DC control.DISCUSSION & CONCLUSIONS: NaOH treatment is a cheap, effective endotoxin removal method that preserves chitosan structure. Resultant chitosan‐genipin hydrogels synthesised with NaOH‐treated chitosan are biocompatible with moDCs, as they do not induce cell death or maturation.Keywords: Biomaterials, Hydrogels and injectable systemsOP‐006 CELL GUIDING FIBROIN/CHITOSAN FILMS MADE by ATMOSPHERIC PLASMA DEPOSITIONDevid Maniglio1, Alberto Quaranta2, Antonella Motta1, Artem Arkhangelskiy11University of Trento, BIOtech center for Biomedical Technologies, Trento, 38123, Italy2University of Trento, Department of Industrial Engineering, Trento, 38123, ItalyINTRODUCTION: Natural polymers are largely proposed as bioactive coatings but their application to surfaces are limited by several factors, such as limited control on the mechanical and chemical stability and weak adhesion to the underlying surface. [1]Plasma process provides unique features, such as surface activation, functionalization or assisted polymerization, which can be obtained using mild conditions. Plasma modification can enhance the adhesion via covalent bonding between functional the groups forming at the interface between the substrate and the coating. On the other side, commonly adopted cold plasma processes imply limited coating thickness and topography control.In this research, we present a new methodology to obtain spatially controlled deposition of natural biopolymers (silk fibroin and chitosan) using an atmospheric plasma torch feeded by an aerosol aqueous solution containing the polymers to be deposited [2].METHODS: The resulting coatings were characterized by electron and atomic force microscopy and ATR‐FTIR. The stability of the films were tested in phosphate‐buffered saline (PBS) solution (pH 7.4) for 2 weeks at 37 °C, followed by treatment in sonication bath for 10 min. Adhesion strength was evaluated by peeling test.RESULTS: The presented plasma process provides unique features in one step, such as surface activation, functionalization or assisted polymerization. Coatings can be obtained using extreme low power (10 W) and room temperature, resulting having excellent adhesion and stability on a large variety of materials, even with complex shape geometries: a soda‐lime glass, a metal alloy (Ti4Al6V), a thermoplastic polymer (polyethylene terephthalate), a silicone rubber (poly‐dimethylsiloxane), without any need of surface pretreatment.The developed method was also successfully optimized for multiple layer deposition of fibroin‐on‐chitosan and chitosan‐on‐fibroin, with the aim to realize patterned surfaces.The biological response of these patterned surfaces were then tested for protein adsorption and cell culture experiments, evidencing their capacity to guide cell adhesion and control cell proliferation.DISCUSSION & CONCLUSIONS: This method allows to achieve spatially controlled deposition, even on complex shaped substrates, together with deposition of different biomaterials in mild condition. This versatility can represent a powerful method for obtaining instructive biosubstrates with optimized tissue interaction, suitable for application in biomedical implants and bioelectronics devices.ACKNOWLEDGEMENTS: This project has received funding from the Italian Ministry for Education, University, and Research (MIUR) thought the “Department of Excellence” program.REFERENCES: [1] Song, Jian et al., Adv. Mater. Interfaces (2020): 2000850.[2] Arkhangelskiy, Artem et al., Adv. Mater. Interfaces (2021): 2100324.Keywords: Biomaterials, Interfaces ‐ engineeredOP‐007 Therapeutically targeting cell function using organosolv lignin – an abundant and emerging sustainable biomass source of raw material for tissue engineering strategiesMelanie L Hart, Mischa Selig, Kathrin Walz, Saman Azizi, Jasmin C Lauer, Bernd RolauffsG.E.R.N. Center for Tissue Replacement, Regeneration & Neogenesis, Department of Orthopedics and Trauma Surgery, Faculty of Medicine, Medical Center—Albert‐Ludwigs‐University of Freiburg, Freiburg im Breisgau, GermanyINTRODUCTION: Lignin biomass is an emerging sustainable source of raw material. It can be used as an eco‐friendly precursor for innovative biomaterials and its utilization in the biomedical tissue engineering field is exponentially growing due to interest in the conversion of abundant biogenic waste with chemical value into valuable materials. We investigated whether lignin could be used to control the phenotype of dedifferentiating and diseased chondrocytes for its use in cartilage tissue engineering applications. Lignins have diverse therapeutic properties but these properties depend on the biomass source and method of extraction, which can affect the physical and chemical properties of lignin. Organosolv lignins (OL) are extracted via a green‐processing approach to obtain high yields of pure lignin that resemble its native molecular structure. We recently characterized fractionated OL from hardwood and showed that the low molecular weight (MW) fraction of OL had more numerous aliphatic hydroxyl functionalities and condensed phenolic structures, a less branched conformation and an increased hydrogen bonding capacity vs. a high MW fraction and was biocompatible with several cell types commonly used in tissue engineering. Due to these characteristics, we hypothesized that low MW OL could promote intermolecular interactions with chondrocytes and thereby modify the phenotype of diseased chondrocytes by changing the cell morphology and phenotype into a healthier phenotype.METHODS: Diseased chondrocytes were isolated from osteoarthritic (OA) cartilage tissue. Passage 1 chondrocytes from n = 4‐8 different donors were treated with low MW OL.RESULTS: In already diseased OA chondrocytes, low MW OL significantly decreased the gene expression levels of COL1A2, an unhealthy phenotypic marker of OA and showed a trend in increasing COL2A1, a healthy phenotypic marker. Thus, low MW OL significantly modified multi‐factorial aspects of chondrocyte cell morphology and induced a less fibroblastic cell morphology and therefore healthier cell shape, which correlated with positive changes in the gene expression. Incorporation of low MW OL into hydrogels significantly increased scaffold stiffness and viscosity as well as chondrocyte attachment, demonstrating biocompatibility of low MW OL in a tissue engineering scaffold.DISCUSSION & CONCLUSIONS: This can open up new possibilities for using OL in tissue engineering strategies for therapeutically targeting cell function.Keywords: Cartilage / joint and arthritic conditions, Biologics and growth factorsOP‐008 Extracellular Vesicles for bone repair/regeneration: modulating the cross‐talk between immune cells and Mesenchymal Stem/Stromal CellsSusana G Santos1, Andreia M Silva2, Joana Oliveira2, José H Teixeira2, Maria Inês Almeida2, Nuno Neves3, Carla Cunha1, Mario A Barbosa21INEB ‐ Instituto de Engenharia Biomédica, and i3S ‐ Instituto de Investigação e Inovação em Sauúde, da Universidade do Porto, Portugal2INEB ‐ Instituto de Engenharia Biomédica, and i3S ‐ Instituto de Investigação e Inovação em Sauúde, da Universidade do Porto, Portugal; ICBAS ‐ Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Portugal.3Serviço de Ortopedia, Hospital CUF, Porto, Portugal; INEB ‐ Instituto de Engenharia Biomédica, and i3S ‐ Instituto de Investigação e Inovação em Sauúde, da Universidade do Porto, PortugalINTRODUCTION: Bone defects and fractures caused by injury or trauma require hospital treatment and often temporary loss of mobility, representing an important economic burden for societies and health systems worldwide. Non‐union or delayed union occur in 5‐10% of fractures, these are worsened by ageing and chronic inflammation, and current therapies cannot overcome this challenge. New cell‐based therapies for bone regeneration are being researched at pre‐clinical and clinical levels, mostly involving Mesenchymal Stem/Stromal Cell (MSC) transplantation. Yet, clinical use of MSC involves important risks, and MSC positive impact in tissue repair, including their immunomodulatory role, are ascribed to paracrine factors, particularly their secreted Extracellular Vesicles (EV)[1]. We previously showed that Dendritic Cell (DC)‐EV can recruit MSC[2], but their role in inflammation to repair transition remains unknown. Herein we aimed to study the impact of bone injury microenvironment on immune cell produced EV and their cross‐talk with MSC.METHODS: Bone Marrow DC and macrophages were obtained from a rat bone defect model, 3 and 14 days after injury. Rat MSC and skin fibroblasts were isolated and characterised. EV were produced in media containing EV‐depleted FBS, isolated by differential (ultra)‐centrifugation, and characterised by transmission electron microscopy, nanoparticle tracking analysis and Western blot. Cell recruitment was investigated by transwell migration assays.RESULTS: The results obtained show that the ability of DC‐EV to recruit MSC changes significantly with time after bone injury. EV secreted by DC obtained 3 days after bone injury impaired MSC migration, while those from DC obtained 14 days after bone injury significantly promoted MSC recruitment. DC‐EV were more efficient in recruiting MSC than macrophage‐EV. Moreover DC‐EV did not impact MSC proliferation or differentiation and did not promote fibroblast recruitment.DISCUSSION & CONCLUSIONS: These results support that EV act specifically, and confirm our previous report on DC‐EV ability to recruit MSC[2].This work contributes to the development of new EV‐based therapies, to accelerate the transition between inflammation and repair, thus improving bone healing in ageing and disease.ACKNOWLEDGEMENTS: Work funded by “Fundo Europeu de Desenvolvimento Regional” (FEDER), through “Programa Operacional Competitividade e Internacionalização e Programa Operacional Regional de Lisboa”, Portugal 2020, Incentive scheme to support research and technological development (SII&DT) ‐ company I&D ‐ “Projetos Em Copromoção” (RESET_BONE_AGEING: POCI‐01‐0247‐FEDER‐069790, LISBOA‐01‐0247‐FEDER‐069790).REFERENCES: 1.Santos, S.G., et al., CHAPTER 10 in Extracellular Vesicles: Applications to Regenerative Medicine, Therapeutics and Diagnostics. 2022, The Royal Society of Chemistry. p. 246‐270.2.Silva, A.M., et al., Sci Rep, 2017. 7(1): p. 1667.Keywords: Bone and bone disorders (osteoporosis etc), Immunity / immunomodulation / macrophageOP‐009 Uniaxial compression promotes osteogenic response of hBM‐MSCs and suppresses osteoclastogenic response of hPBMCs in co‐culture within composite scaffoldsMaria Chatzinikolaidou1, Georgia Ioanna Kontogianni1, Konstantinos Loukelis1, Amedeo Franco Bonatti2, Elisa Batoni2, Carmelo De Maria2, Raasti Naseem3, Giovanni Vozzi2, Kenneth Dalgarno3, Nicholas Dunne4, Chiara Vitale Brovarone51Department of Materials Science and Technology, University of Crete, Heraklion, Greece2Research Center E. Piaggio and Dpt. of Information Engineering, University of Pisa, Pisa, Italy3School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom4School of Mechanical & Manufacturing Engineering, Dublin City University, Ireland5Department of Applied Science and Technology, Politecnico di Torino, Turin, ItalyINTRODUCTION: Bone is a highly dynamic tissue that undergoes continuous remodeling through lifetime regulated by bone forming osteoblasts and bone resorbing osteoclasts. Mechanical stimuli applied on bone tissue can shift the balance between these two cell populations [1]. In this study, the application of uniaxial compression in a 3D co‐culture comprising human bone marrow mesenchymal stem cells (hBM‐MSCs) and human peripheral blood mononuclear cells (hPBMCs) was evaluated [2]. The two cell populations were seeded onto 3D scaffolds produced by fused deposition modeling. The scaffolds composition was 90/5/5 %wt of poly‐L‐lactic acid, polycaprolactone and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) substituted with 2.5% wt strontium‐nano‐hydroxyapatite.METHODS: hBM‐MSCs (7x104 cells/scaffold) were seeded and cultured under static and dynamic culture conditions for 13 days, followed by the addition of hPBMCs (50x104 cells/scaffold) and application of mechanical stimulation every other day for 25 min at a frequency of 1 Hz and a strain at 8% of the scaffold side (400 μm of displacement). Cell proliferation and morphology were monitored via a reduction‐based cell viability assay, scanning electron microscopy (SEM) and confocal microscopy. Measurements of the alkaline phosphatase (ALP) and tartrate acid phosphatase (TRAP) activity were conducted to determine the effect of the scaffolds on the osteogenesis and osteoclastogenesis. Quantitative polymerase chain reaction was applied to quantify gene expression changes of osteogenesis‐related markers (osteonectin, osteoprotegerin and osteocalcin), and osteoclastogenesis‐related markers (TRAP, dendritic cell‐specific transmembrane protein and nuclear factor of activated T cells 1).RESULTS: The cell viability assessment displays excellent biocompatibility, while SEM and confocal microscopy images display well‐spread cells. After 14 and 28 days, the ALP activity is higher in the dynamic co‐culture compared to the static one and the corresponding hBM‐MSCs mono‐culture. The TRAP activity results showed a significantly lower TRAP activity in the dynamic co‐culture than in the static co‐culture and the hPBMCs mono‐culture after 14 days. Gene expression of osteogenesis related markers was significantly higher in the dynamic co‐culture than in the static and mono‐cultures of hBM‐MSCs.DIS