Browsing by Author "Gokalp, S"

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    Therapeutic and protective effects of autologous serum in amikacin-induced ototoxicity
    Arslan, IB; Aslan, GG; Mercan, GC; Vatansever, S; Cukurova, I; Gokalp, S; Aslan, A
    Objective: Possible therapeutic and protective benefits of intratympanic autologous serum application in amikacin-induced ototoxicity were investigated. Methods: Twenty-four guinea pigs were separated equally into two groups: therapeutic (group A) and protective (group B). Transient evoked otoacoustic emissions were recorded before and after autologous serum application. Apoptotic cells were identified in the organ of Corti, spiral limbus and spiral ganglion by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling ('TUNEL') method. Results: Transient evoked otoacoustic emission responses at 1, 1.4 and 2.8 kHz improved without significance after autologous serum application in group A (p > 0.05). A significantly protective effect of autologous serum was determined at 4 kHz in group B (p < 0.05). There were significantly fewer apoptotic cells at the spiral limbus in the therapeutic and protective groups compared to the control group (p < 0.05). Conclusion: Autologous serum may offer protection against ototoxicity-induced hearing loss, but it cannot restore hearing. Immunohistochemically, autologous serum significantly decreases activation of the intrinsic pathway of pro-apoptotic signalling in mesenchymal cells compared to neurons and neurosensory cells.
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    The importance of miRNA expressions in Infertilty
    Gokalp, S; Akgul, B; Ozcakir, T; Vatansever, HS
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    Synergistic role of three dimensional niche and hypoxia on conservation of cancer stern cell phenotype
    Gorgun, C; Ozturk, S; Gokalp, S; Vatansever, S; Gurhan, SID; Urkmez, AS
    Hypoxia is a pathalogical condition in which tissues are deprived of adequate oxygen supply. The hypoxia effect on tumors has a critically important role on maintenance of cancer stem cell phenotype. The aim of this study is to investigate the effects of hypoxia on cancer stem cells on three dimensional (3D) in vitro culture models. Osteosarcoma stem cells characterized by CD133 surface protein were isolated from osteosarcoma cell line (SaOS-2) by magnetic-activated cell sorting (MACS) technique. Isolated CD133(+) and CD133(-) cells were cultivated under hypoxic (1% O-2) and normoxic conditions (21% O-2) for 3 days. For the 3D model, bacterial cellulose scaffold was used as the culture substrate. 3D morphologies of cells were examined by scanning electron microscopy (SEM); RT-PCR and immunocytochemistry staining were used to demonstrate conservation of the cancer stem cell phenotype in 3D environment under hypoxic conditions. Cell viability was shown by MTT assay on 3. and 7. culture days. This study is seen as an introduction to develop a 3D hypoxic cancer stem cell based tumor model to study CSC behavior and tumor genesis in vitro. (C) 2016 Published by Elsevier B.V.
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    Development and characterization of cancer stem cell-based tumoroids as an osteosarcoma model
    Ozturk, S; Gorgun, C; Gokalp, S; Vatansever, S; Sendemir, A
    Three-dimensional (3D) cancer tumor models are becoming vital approaches for high-throughput drug screening, drug targeting, development of novel theranostic systems, and personalized medicine. Yet, it is becoming more evident that the tumor progression and metastasis is fueled by a subpopulation of stem-like cells within the tumor that are also called cancer stem cells (CSCs). This study aimed to develop a tumoroid model using CSCs. For this purpose CD133(+) cells were isolated from SaOS-2 osteosarcoma cell line with magnetic-activated cell sorting. To evaluate tumoroid formation ability, the cells were incubated in different cell numbers in agar gels produced by 3D Petri Dish (R) method. Subsequently, CD133(+) cells and CD133(-) cells were co-cultured to investigate CD133(+) cell localization in tumoroids. The characterization of tumoroids was performed using Live&Dead staining, immunohistochemistry, and quantitative polymerase chain reaction analysis. The results showed that, CD133(+), CD133(-) and SaOS-2 cells were all able to form 3D tumoroids regardless of the initial cell number, but, while 72 hr were needed for CD133(+) cells to self-assemble, 24 hr were enough for CD133(-) and SaOS-2 cells. CD133(+) cells were located within tumoroids randomly with high cell viability. Finally, when compared to two-dimensional (2D) cultures, there were 5.88, 4.14, 6.95, and 1.68-fold higher messenger RNA expressions for Sox2, OCT3/4, Nanog, and Nestin, respectively, in CD133(+) cells that were cultured within 3D tumoroids, showing longer maintenance of stem cell phenotype in 3D, that can allow more relevant screening and targeting efficiency in pharmaceutical testing. It was concluded that CSC-based tumoroids are propitious as 3D tumor models to fill the gap between conventional 2D in vitro culture and in vivo animal experiments for cancer research.