Bioreactors in tissue engineering: mimicking the microenvironment

One of the main challenges that have kept tissue-engineered constructs from being widely adopted to clinics is poor cell survival due to limited mass transfer of oxygen and nutrients in thick, clinically relevant sizes of constructs. Tissue engineering bioreactors have been developed to overcome this mass transfer problem, introducing convection as well as diffusion in three-dimensional culture systems. They also provide highly controlled microenvironments for viability, repeatability, and standardization. This microenvironment can mimic the physiological niche, so that functional tissue maturation can be achieved. In this chapter the properties of different types of bioreactors that are commonly used for tissue engineering (TE) applications are examined. This chapter summarizes the main types of bioreactors used for TE, focusing on their design parameters and comparing their main prominences for particular applications. © 2020 Elsevier Ltd. All rights reserved

Mechanobiology of cells and cell systems, such as organoids

Organoids are in vitro 3D self-organizing tissues that mimic embryogenesis. Organoid research is advancing at a tremendous pace, since it offers great opportunities for disease modeling, drug development and screening, personalized medicine, as well as understanding organogenesis. Mechanobiology of organoids is an unexplored area, which can shed light to several unexplained aspects of self-organization behavior in organogenesis. It is becoming evident that collective cell behavior is distinctly different from individual cells’ conduct against certain stimulants. Inherently consisting of higher number of degrees of freedom for cell motility and more complex cell-to-cell and cell-to-extracellular matrix behavior, understanding mechanotransduction in organoids is even more challenging compared with cell communities in 2D culture conditions. Yet, deciphering mechanobiology of organoids can help us understand effects of mechanical cues in health and disease, and translate findings of basic research toward clinical diagnosis and therapy. © 2019, International Union for Pure and Applied Biophysics (IUPAB) and Springer-Verlag GmbH Germany, part of Springer Nature.2010K120810, 16217 European Cooperation in Science and Technology, COST: 16122The authors acknowledge COST Action 16122 (BIONECA) for financing Prof. Dr. Yannis F. Missirlis for an STSM to visit and collaborate with the rest of the authors at Ege University; COST Action 16217 (ENIUS) for designating him as a disseminator to ?promote? the Action at 4th international Symposium on Nanoengineering for Mechanobiology (N4M), where some of the ideas presented in this review were discussed; and Republic of Turkey Ministry of Development [EGEMATAL;2010K120810] for financing Dr. Ece Bayir

The squatting facets on the tibia of Byzantine (13th) skeletons

Squatting is a resting postural complex that involves hyper-flexion at the hip and knee joints, and hyper-dorsiflexion at the ankle and subtalar joints. The effects of squatting stress may induce bone remodeling. Different incidences of these modifications reflect the life style of a population. Stress-induced bone remodeling may be the result of physical and sports performance, especially that of women. We investigated 125 tibia from adult male skeletons from the late Byzantine period (13th century) to see if they had squatting facets or not. Thirty-one tali pairing tibia were also investigated concerning their relationship with the squatting facets of these bones. There were 64 right (51.2%) and 61 left (48.8%) tibia and squatting facets were observed on 30 right (46.9%) and 30 left (49.2%) tibia. Among the 25 paired tibia investigated, squatting facets were seen on 9 (36%) pairs and there was no evidence of side predilection. On the right side, squatting facets occurred on 3 (20%) tibia-tali; on the left side they were present on 7 (43.7%) tibia-tali, and only one tibia had the squatting facet and tali had none. The occurrence of squatting facets in this Byzantine population was greater than that reported for modern Europeans, but less than for Australians and Indians. Therefore, different factors can play a role in the modifications of the distal tibia surface, articulating with the talus

Production of hydroxyapatite–bacterial cellulose composite scaffolds with enhanced pore diameters for bone tissue engineering applications

2-s2.0-85074012252Abstract: Bone tissue engineering scaffolds used for the treatment of bone defects are required to be osteoconductive, osteoinductive, osteogenic, biocompatible, and have enough porosity to allow osteointegration, as well as vascularization. It is known that addition of the hydroxyapatite (HAp) to bone tissue scaffolds promotes bone formation by increasing osteoconductivity. Bacterial cellulose (BC) is a highly biocompatible material, and its mechanical properties and fibrous structure allow that it can be used as a bone tissue scaffold; yet, the nano-porous structure of BC (50–200 nm) prevents or limits cell migration and vascularization. In this study, it is intended to take advantage of the porous structure and mechanical strength of BC and osteoconductive properties of HAp for the production of tissue engineering scaffolds. Pore sizes of BC were enhanced to 275 ?m by a novel shredded agar technique, and SaOs-2 cells were shown to migrate between the fibers of the modified BC. It was observed that mineralization of SaOs-2 cells was enhanced on in situ produced HAp-BC nano-composites compared to BC scaffolds. Graphic abstract: [Figure not available: see fulltext.] © 2019, Springer Nature B.V.13FBE008, 2010K120810 113M243 Türkiye Bilimsel ve Teknolojik Araştirma Kurumu, TÜBITAKThis work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) through COST project (113M243) and TUBITAK 2211-C Domestic Graduate Scholarship Program and Ege University Scientific Research Projects Council (13FBE008) and Republic of Turkey Ministry of Development [EGE MATAL; 2010K120810]. The authors thank Ko? University Research Center for Translational Medicine (KUTTAM) and Assist. Prof. Ser?in Karah?seyino?lu for the use of the confocal microscopy.This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) through COST project (113M243) and TUBITAK 2211-C Domestic Graduate Scholarship Program and Ege University Scientific Research Projects Council (13FBE008) and Republic of Turkey Ministry of Development [EGE MATAL; 2010K120810]. The authors thank Koç University Research Center for Translational Medicine (KUTTAM) and Assist. Prof. Serçin Karahüseyinoğlu for the use of the confocal microscopy

Novel keratin modified bacterial cellulose nanocomposite production and characterization for skin tissue engineering

WOS: 000400720800131PubMed ID: 28415399As it is known that bacterial cellulose (BC) is a biocompatible and natural biopolymer due to which it has a large set of biomedical applications. But still it lacks some desired properties, which limits its uses in many other applications. Therefore, the properties of BC need to be boosted up to an acceptable level. Here in this study for the first time, a new natural nanocomposite was produced by the incorporating keratin (isolated from human hair) to the BC (produced by Acetobacter xylinum) to enhance dermal fibroblast cells' attachment. Two different approaches were used in BC based nanocomposite production: in situ and post modifications. BC/keratin nanocomposites were characterized using SEM, FTIR, EDX, XRD, DSC and XPS analyses. Both production methods have yielded successful results for production of BC based nanocomposite-containing keratin. In vitro cell culture experiments performed with human skin keratinocytes and human skin fibroblast cells indicate the potential of the novel BC/keratin nanocomposites for use in skin tissue engineering. (C) 2017 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114M082]; Ege University Science and Technology Centre - Scientific Research Projects Council [15BIL022]This study was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) grant number 114M082, Ege University Science and Technology Centre - Scientific Research Projects Council grant number 15BIL022. The authors would like to thank Prof. Figen Zihnioglu (Department of Biochemistry at Ege University) and Asst. Prof. Dr. Mehmet Sarikanat for their valuable contributions

Protective Effects of Astragaloside IV and Cycloastragenol in 6-hydroxydopamin (6-OHDA)-Induced Neurotoxicity in PC12 Cells

59th International Congress and Annual Meeting of the Society-for-Medicinal-Plant-and-Natural-Product-Research -- SEP 04-09, 2011 -- Antalya, TURKEYWOS: 000294139000858Soc Med Plant & Nat Prod Re

The effects of different intensities, frequencies and exposure times of extremely low-frequency electromagnetic fields on the growth of Staphylococcus aureus and Escherichia coli O157:H7

PubMed ID: 24279632The impact of different types of extremely low-frequency electromagnetic fields (ELF-EMF) on the growth of Staphylococcus aureus and Escherichia coli O157:H7 was investigated. The cultures of bacteria in broth media were exposed to sinusoidal homogenous ELF-EMF with 2 and 4mT magnetic intensities. Each intensity for each bacteria was combined with three different frequencies (20, 40 and 50 Hz), and four different exposure times (1, 2, 4 and 6 h). A cell suspension of each experiment was diluted for the appropriate range and inoculated to Mueller-Hinton Agar (MHA) plates after exposure to ELF-EMF. The number of colony forming units (CFU) of both strains was obtained after incubation at 37°C for 24 h. Data were statistically evaluated by one-way analysis of variance (ANOVA), statistical significance was described at p<0.05 and data were compared with their non-exposed controls. Magnetic intensity, frequency and exposure time of ELF-EMFs changed the characteristic responses for both microorganisms. Samples exposed to ELF-EMF showed a statistically significant decrease compared to their controls in colony forming capability, especially at long exposure times. An exposure to 4mT-20 Hz ELF-EMF of 6 h produced maximum inhibition of CFU compared to their controls for both microorganisms (95.2% for S. aureus and 85% for E. coli). © 2015 Informa Healthcare USA, Inc.This work supported by The Scientific and Technological Research Council of Turkey (TUBITAK) within the funding programme 2209. The authors declare no conflict of interests. The authors alone are responsible for the content and writing of the article. -

Optimization of bacterial cellulose production by Gluconacetobacter xylinus using carob and haricot bean

International Biomedical Engineering Congress -- 2015 -- Near E Univ, North Nicosia, CYPRUSWOS: 000380626900002PubMed ID: 26906562Bacterial cellulose (BC) can be used in medical, biomedical, electronic, food, and paper industries because of its unique properties distinguishing it from plant cellulose. BC production was statistically optimized by Gluconacetobacter xylinus strain using carob and haricot bean (CHb) medium. Eight parameters were evaluated by Plackett-Burman Design and significant three parameters were optimized by Central Composite Design. Optimal conditions for production of BC in static culture were found as: 2.5 carbon source, 2.75 g/L protein source, 9.3% inoculum ratio, 1.15 g/L. citric acid, 2.7 g/L Na2HPO4, 30 degrees C incubation temperature, 5.5 initial pH, and 9 days of incubation. This study reveals that BC production can be carried out using carob and haricot bean extracts as carbon and nitrogen sources, and CHb medium has higher buffering capacity compared to Hestrin and Schramm media. Model obtained from this study is used to predict and optimize BC production yield using CHb medium. (C) 2016 Elsevier B.V. All rights reserved