Browsing by Subject "Mesenchymal stem cell"

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Open Access
Administration of bone marrow derived mesenchymal stem cells modulate tlr expression during liver regeneration
(Trakya Üniversitesi, 2019) Koçak, H.; Tokçaer Keskin, Z.; İnsal, B.; Gürsel, İhsan; Akçalı, K. C.
Liver cell transplantation is a powerful alternative to orthotopic cell transplantation in the treatment of liver failures. Recently, considerable effort is being channeled to understand the nature and kinetics of directing stem cells to effectively accumulate at the regenerating liver site. Mesenchymal stem cells are one of the promising cell sources modulating liver regeneration process. The present was designed to study how mesenchymal stem cells might modulate liver immune behaviors by changing Toll-like receptor (TLR) expression and increase regenerative potential during liver regeneration in rats. Normal and partially hepatectomized rats were treated with mesenchymal stem cells isolated and expanded from rat bone marrows. Accumulation of mesenchymal stem cells was confirmed by Real Time-Polymerase Chain Reaction (RT-PCR), Fluorescence-Activated Cell Sorting (FACS), and Immunofluorescence Staining (IFS). Student's t-test analysis was used to evaluate the significance of differences between sham and partially hepatectomized rat groups. Our results showed that mesenchymal stem cells expressed several TLRs, and their accumulation during regeneration was depended on the timing of injury. Mesenchymal stem cells isolated from bone marrow of normal rats were observed at the injured liver 3 days after the injection. There were no labeled mesenchymal stem cells in the liver sections of the uninjured animals. Mesenchymal stem cell administration significantly altered the expression of TLR2, 3 and 9 while retaining their migration potential to regenerating liver. Our findings implicated that mesenchymal stem cell administration during liver regeneration modulate the immune response through changing the expression of the TLRs in the remaining liver parts into which the cells are recruited or infused. This alteration may contribute to the regeneration process following partial hepatectomy.
Open Access
Bioactive glycopeptide nanofibers for tissue regeneration applications
(2016-05) Çalışkan, Özüm Şehnaz.
Natural extracellular matrix (ECM) is rich in glycopeptides and glycosaminoglycans, which function in controlling cellular processes. In this thesis, glycopeptide molecules that mimic natural glycopeptides and glycosaminoglycans were designed and synthesized and it was demonstrated that they induce directed differentiation of mesenchymal stem cells into chondrogenic and adipogenic lineages. In the first part of the study, hyaluronic acid (HA)-mimicking glycopeptide amphiphile molecules were synthesized to induce chondrogenic differentiation of mesenchymal stem cells (MSC). HA is the most abundant glycosaminoglycan (GAG) found in hyaline cartilage ECM. Peptide amphiphiles were synthesized by solid phase peptide synthesis method and used to form self-assembled bioactive glycopeptide nanofibers which mimic fibrous morphology of the ECM. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and circular dichroism (CD) were used for morphology and secondary structure analyses of the obtained nanofibers. It was demonstrated that glycopeptide amphiphiles create fibrous structure formed by nanofibers. Morphological changes, GAG production (Safranin-O staining and DMMB analysis), and chondrogenic gene marker expressions (qRT-PCR) of MSCs cultured on HA-mimetic nanofibers were analyzed. It was shown that HA-mimetic glycopeptide nanofibers induce early differentiation of MSCs into hyaline like chondrocytes. In the second part of the study, it was demonstrated that minor changes on glycopeptide backbone can create specific glycopeptides which induce differentiation of MSCs into brown adipocytes. Brown fat adipocytes do not store chemical energy as fat but dissipates it as heat and so they have emerged as promising anti-obesity agents. Lipid droplet accumulation (Oil Red-O staining) and adipogenic gene marker expression analyses (qRT-PCR) showed that the new glycopeptide nanofiber scaffold is a specific inducer of differentiation of MSCs into brown fat adipocytes.
Open Access
Bioactive peptide nanofibers for bone tissue regeneration
(2017-06) Tansık, Gülistan
Replacement and repair of bone tissue that is lost due to fractures, tumor resection, degenerative diseases and infections still remain major clinical challenges. Autografting, allografting and xenografting are the current strategies for the treatment of bone defects. However, these strategies cause problems such as immunological response and disease transmission in clinical applications. To overcome these limitations, regeneration of new bone can be induced by the use of synthetic bioactive materials. One of the most promising strategies is to develop synthetic scaffolds mimicking the functional components of the extracellular matrix (ECM). Biomineralization is mineralization carried out by living organisms. Glycosaminoglycans have crucial roles in biomineralization and enhance the functions of growth factors involved in biomineralization. Success in bone regeneration studies requires a thorough understanding of the necessary conditions for triggering biomineralization during the bone tissue formation process. In this study, the effect of bioactive and biocompatible peptide nanofibers on osteogenic differentiation, biomineralization and bone tissue regeneration are investigated under in vitro and in vivo conditions. In the first chapter, bone tissue composition, the clinical need for bone regeneration and general principles in bone tissue engineering are discussed. Bone tissue regeneration strategies are also highlighted in this part, with emphasis on peptide amphiphiles and self-assembly behavior. In the second chapter, a fully synthetic, extracellular matrix-mimetic peptide nanofiber system is described for enhancing the biomineralization and regeneration of bone tissue. This nanostructural environment forms artificial intracellular networks and supports biomineralization by providing cell-material and protein-material interactions. In the third chapter, effect of osteoinductive peptide nanofibers on osteogenic differentiation of rat mesenchymal stem cells (MSCs) were investigated. In the fourth chapter, the natural biomineralization process in bone tissue was mimicked on peptide nanofibers and the effect of this system on the osteogenic differentiation of osteoblast-like cells was investigated. In the fifth chapter, a dentin-mimetic peptide amphiphile (SpDSp-PA) molecule that is capable of emulating the structure and function of dentin phosphoprotein was designed and its capacity to support the deposition of hydroxyapatite and survival and biomineralization of osteoblast-like cells was evaluated.
Open Access
Biological properties of extracellular vesicles and their physiological functions
(Taylor & Francis, 2015) Yáñez-Mó, M.; Siljander, P. R. M.; Andreu, Z.; Zavec, A. B.; Borràs, F. E.; Buzas, E. I.; Buzas, K.; Casal, E.; Cappello, F.; Carvalho, J.; Colás, E.; Cordeiro-Da, S. A.; Fais, S.; Falcon-Perez, J. M.; Ghobrial, I. M.; Giebel, B.; Gimona, M.; Graner, M.; Gursel, I.; Gursel, M.; Heegaard, N. H. H.; Hendrix, A.; Kierulf, P.; Kokubun, K.; Kosanovic, M.; Kralj-Iglic, V.; Krämer-Albers, E. M.; Laitinen, S.; Lässer, C.; Lener, T.; Ligeti, E.; Line, A.; Lipps, G.; Llorente, A.; Lötvall, J.; Manček-Keber, M.; Marcilla, A.; Mittelbrunn, M.; Nazarenko, I.; Nolte-'t Hoen, E. N. M.; Nyman, T. A.; O'Driscoll, L.; Olivan, M.; Oliveira, C.; Pállinger, E.; Del Portillo, H. A.; Reventós, J.; Rigau, M.; Rohde, E.; Sammar, M.; Sánchez-Madrid, F.; Santarém, N.; Schallmoser, K.; Ostenfeld, M. S.; Stoorvogel, W.; Stukelj, R.; Grein V. D. S.G.; Helena,ü V. M.; Wauben, M. H. M.; De Wever, O.
In the past decade, extracellular vesicles (EVs) have been recognized as potent vehicles of intercellular communication, both in prokaryotes and eukaryotes. This is due to their capacity to transfer proteins, lipids and nucleic acids, thereby influencing various physiological and pathological functions of both recipient and parent cells.While intensive investigation has targeted the role of EVs in different pathological processes, for example, in cancer and autoimmune diseases, the EV-mediated maintenance of homeostasis and the regulation of physiological functions have remained less explored. Here, we provide a comprehensive overview of the current understanding of the physiological roles of EVs, which has been written by crowd-sourcing, drawing on the unique EV expertise of academia-based scientists, clinicians and industry based in 27 European countries, the United States and Australia. This review is intended to be of relevance to both researchers already working on EV biology and to newcomers who will encounter this universal cell biological system. Therefore, here we address the molecular contents and functions of EVs in various tissues and body fluids from cell systems to organs. We also review the physiological mechanisms of EVs in bacteria, lower eukaryotes and plants to highlight the functional uniformity of this emerging communication system.
Open Access
Chondrogenic differentiation of mesenchymal stem cells on glycosaminoglycan-mimetic peptide nanofibers
(American Chemical Society, 2016) Yaylaci, S .U.; Sen, M.; Bulut, O.; Arslan, E.; Güler, Mustafa O.; Tekinay, A. B.
Glycosaminoglycans (GAGs) are important extracellular matrix components of cartilage tissue and provide biological signals to stem cells and chondrocytes for development and functional regeneration of cartilage. Among their many functions, particularly sulfated glycosaminoglycans bind to growth factors and enhance their functionality through enabling growth factor-receptor interactions. Growth factor binding ability of the native sulfated glycosaminoglycans can be incorporated into the synthetic scaffold matrix through functionalization with specific chemical moieties. In this study, we used peptide amphiphile nanofibers functionalized with the chemical groups of native glycosaminoglycan molecules such as sulfonate, carboxylate and hydroxyl to induce the chondrogenic differentiation of rat mesenchymal stem cells (MSCs). The MSCs cultured on GAG-mimetic peptide nanofibers formed cartilage-like nodules and deposited cartilage-specific matrix components by day 7, suggesting that the GAG-mimetic peptide nanofibers effectively facilitated their commitment into the chondrogenic lineage. Interestingly, the chondrogenic differentiation degree was manipulated with the sulfonation degree of the nanofiber system. The GAG-mimetic peptide nanofibers network presented here serve as a tailorable bioactive and bioinductive platform for stem-cell-based cartilage regeneration studies.
Open Access
Design and development of ecm-inspired peptidebased nanostructures for bioengineering and biomedicine
(2017-08) Arslan, Elif
Advances in understanding of cell-matrix interactions and the regulation of cellular behaviors through nanobiotechnological tools have presented new perspectives for regenerative medicine. Peptide amphiphiles have been used as building blocks for development of bioactive synthetic nanofiber scaffolds for regenerative medicine applications. Biocompatibility, tailorable characteristics, and mechanical stability as well as bioactivitiy of these peptide nanostructures make them ideal candidates for biomedical applications. To guide natural cellular activities, biomaterials should provide a microenvironment similar to that experienced by cells under natural conditions. The native extracellular matrix (ECM) not only provides a suitable physical environment but also incorporates the necessary set of biochemical and mechanical signals to ensure the normal function of cells, as well as mediating their differentiation, morphogenesis and homeostasis by providing biological, physical, and chemical recognition signals that can trigger specific interactions with cell surface receptors. In this thesis, different ECM-mimetic peptide nanofiber formulations were designed and developed, which were shown to have superior chondrogenic and therapeutic effect on stem cell differentiation in vitro and cartilage regeneration in vivo. Hence, the synthetic peptide nanomaterials harbor great promise in mimicking specific ECM molecules as therapeutic agents and model systems.
Open Access
A glycosaminoglycan mimetic peptide nanofiber gel as an osteoinductive scaffold
(Royal Society of Chemistry, 2016) Tansik, G.; Kilic, E.; Beter, M.; Demiralp, B.; K.Sendur, G.; Can, N.; Ozkan, H.; Ergul, E.; Güler, Mustafa O.; Tekinay, A. B.
Biomineralization of the extracellular matrix (ECM) plays a crucial role in bone formation. Functional and structural biomimetic native bone ECM components can therefore be used to change the fate of stem cells and induce bone regeneration and mineralization. Glycosaminoglycan (GAG) mimetic peptide nanofibers can interact with several growth factors. These nanostructures are capable of enhancing the osteogenic activity and mineral deposition of osteoblastic cells, which is indicative of their potential application in bone tissue regeneration. In this study, we investigated the potential of GAG-mimetic peptide nanofibers to promote the osteogenic differentiation of rat mesenchymal stem cells (rMSCs) in vitro and enhance the bone regeneration and biomineralization process in vivo in a rabbit tibial bone defect model. Alkaline phosphatase (ALP) activity and Alizarin red staining results suggested that osteogenic differentiation is enhanced when rMSCs are cultured on GAG-mimetic peptide nanofibers. Moreover, osteogenic marker genes were shown to be upregulated in the presence of the peptide nanofiber system. Histological and micro-computed tomography (Micro-CT) observations of regenerated bone defects in rabbit tibia bone also suggested that the injection of a GAG-mimetic nanofiber gel supports cortical bone deposition by enhancing the secretion of an inorganic mineral matrix. The volume of the repaired cortical bone was higher in GAG-PA gel injected animals. The overall results indicate that GAG-mimetic peptide nanofibers can be utilized effectively as a new bioactive platform for bone regeneration. © 2016 The Royal Society of Chemistry.
Open Access
Glycosaminoglycan-Mimetic Signals Direct the Osteo/Chondrogenic Differentiation of Mesenchymal Stem Cells in a Three-Dimensional Peptide Nanofiber Extracellular Matrix Mimetic Environment
(American Chemical Society, 2016-02) Arslan, E.; Güler, Mustafa O.; Tekinay, A. B.
Recent efforts in bioactive scaffold development focus strongly on the elucidation of complex cellular responses through the use of synthetic systems. Designing synthetic extracellular matrix (ECM) materials must be based on understanding of cellular behaviors upon interaction with natural and artificial scaffolds. Hence, due to their ability to mimic both the biochemical and mechanical properties of the native tissue environment, supramolecular assemblies of bioactive peptide nanostructures are especially promising for development of bioactive ECM-mimetic scaffolds. In this study, we used glycosaminoglycan (GAG) mimetic peptide nanofiber gel as a three-dimensional (3D) platform to investigate how cell lineage commitment is altered by external factors. We observed that amount of fetal bovine serum (FBS) presented in the cell media had synergistic effects on the ability of GAG-mimetic nanofiber gel to mediate the differentiation of mesenchymal stem cells into osteogenic and chondrogenic lineages. In particular, lower FBS concentration in the culture medium was observed to enhance osteogenic differentiation while higher amount FBS promotes chondrogenic differentiation in tandem with the effects of the GAG-mimetic 3D peptide nanofiber network, even in the absence of externally administered growth factors. We therefore demonstrate that mesenchymal stem cell differentiation can be specifically controlled by the combined influence of growth medium components and a 3D peptide nanofiber environment.
Open Access
Presentation of functional groups on self-assembled supramolecular peptide nanofibers mimicking glycosaminoglycans for directed mesenchymal stem cell differentiation
(Royal Society of Chemistry, 2017) Yasa, Oncay; Uysal, Ozge; Ekiz, Melis Sardan; Güler, Mustafa O.; Tekinay, Ayse B.
Organizational complexity and functional diversity of the extracellular matrix regulate cellular behaviors. The extracellular matrix is composed of various proteins in the form of proteoglycans, glycoproteins, and nanofibers whose types and combinations change depending on the tissue type. Proteoglycans, which are proteins that are covalently attached to glycosaminoglycans, contribute to the complexity of the microenvironment of the cells. The sulfation degree of the glycosaminoglycans is an important and distinct feature at specific developmental stages and tissue types. Peptide amphiphile nanofibers can mimic natural glycosaminoglycans and/or proteoglycans, and they form a synthetic nanofibrous microenvironment where cells can proliferate and differentiate towards different lineages. In this study, peptide nanofibers were used to provide varying degrees of sulfonation mimicking the natural glycosaminoglycans by forming a microenvironment for the survival and differentiation of stem cells. The effects of glucose, carboxylate, and sulfonate groups on the peptide nanofibers were investigated by considering the changes in the differentiation profiles of rat mesenchymal stem cells in the absence of any specific differentiation inducers in the culture medium. The results showed that a higher sulfonate-to-glucose ratio is associated with adipogenic differentiation and a higher carboxylate-to-glucose ratio is associated with osteochondrogenic differentiation of the rat mesenchymal stem cells. Overall, these results demonstrate that supramolecular peptide nanosystems can be used to understand the fine-tunings of the extracellular matrix such as sulfation profile on specific cell types. © 2017 The Royal Society of Chemistry.
Open Access
Spatial organization of functional groups on bioactive supramolecular glycopeptide nanofibers for differentiation of mesenchymal stem cells (MSCs) to brown adipogenesis
(American Chemical Society, 2016-12) Caliskan, O. S.; Sardan, Ekiz M.; Tekinay, A. B.; Güler, Mustafa O.
Spatial organization of bioactive moieties in biological materials has significant impact on the function and efficiency of these systems. Here, we demonstrate the effect of spatial organization of functional groups including carboxylate, amine, and glucose functionalities by using self-assembled peptide amphiphile (PA) nanofibers as a bioactive scaffold. We show that presentation of bioactive groups on glycopeptide nanofibers affects mesenchymal stem cells (MSCs) in a distinct manner by means of adhesion, proliferation, and differentiation. Strikingly, when the glutamic acid is present in the glycopeptide backbone, the PA nanofibers specifically induced differentiation of MSCs into brown adipocytes in the absence of any differentiation medium as shown by lipid droplet accumulation and adipogenic gene marker expression analyses. This effect was not evident in the other glycopeptide nanofibers, which displayed the same functional groups but with different spatial organization. Brown adipocytes are attractive targets for obesity treatment and are found in trace amounts in adults, which also makes this specific glycopeptide nanofiber system an attractive tool to study molecular pathways of brown adipocyte formation.
Open Access
Supramolecular GAG-like self-assembled glycopeptide nanofibers Induce chondrogenesis and cartilage regeneration
(American Chemical Society, 2016) Yaylaci, U. S.; Ekiz, M. S.; Arslan, E.; Can, N.; Kilic, E.; Ozkan, H.; Orujalipoor, I.; Ide, S.; Tekinay, A. B.; Güler, Mustafa O.
Glycosaminoglycans (GAGs) and glycoproteins are vital components of the extracellular matrix, directing cell proliferation, differentiation, and migration and tissue homeostasis. Here, we demonstrate supramolecular GAG-like glycopeptide nanofibers mimicking bioactive functions of natural hyaluronic acid molecules. Self-assembly of the glycopeptide amphiphile molecules enable organization of glucose residues in close proximity on a nanoscale structure forming a supramolecular GAG-like system. Our in vitro culture results indicated that the glycopeptide nanofibers are recognized through CD44 receptors, and promote chondrogenic differentiation of mesenchymal stem cells. We analyzed the bioactivity of GAG-like glycopeptide nanofibers in chondrogenic differentiation and injury models because hyaluronic acid is a major component of articular cartilage. Capacity of glycopeptide nanofibers on in vivo cartilage regeneration was demonstrated in microfracture treated osteochondral defect healing. The glycopeptide nanofibers act as a cell-instructive synthetic counterpart of hyaluronic acid, and they can be used in stem cell-based cartilage regeneration therapies.
Open Access
Three dimensional glycosaminoglycan mimetic peptide amphiphile hydrogels for regenerative medicine applications
(2015-05) Tümtaş, Yasin
Defects and impairments of tissues or organs affect millions of people, resulting in considerable losses in workforce and life quality. The treatment of major tissue injuries requires the development of advanced medical techniques that enhance the natural repair processes of the human body. Novel biomaterials can modulate the repair of organs and tissues by providing a suitable environment for the recruitment, proliferation and differentiation of stem and progenitor cells, allowing the recovery of degenerated or otherwise nonfunctional tissues. Peptide amphiphiles (PAs) serve as model biomaterials due to their capacity for self-assembly, which allows peptide monomers to form complex networks that approximate the structure and function of the natural extracellular matrix. Peptide networks can be further modified by the attachment of various epitopes and functional groups, allowing these materials to present bioactive signals to surrounding cells. Glycosaminoglycans (GAGs) are negatively charged, unbranched polysaccharides that constitute a substantial part of the ECM in various tissues and play an important role in maintaining tissue integrity. Therefore, mimicking GAGs presents a suitable means for modulating cell behavior and especially lineage commitment in stem cells. In this work, I describe the design and synthesis of several bioactive, three dimensional (3D) GAG-mimetic peptide amphiphile hydrogels for in vitro stem cell differentiation and in vivo pancreatic islet transplantation. In Chapter 1, I detail the extracellular environment of tissues and the importance of GAGs in maintaining cell and tissue function. In Chapter 2, I describe the in vitro experiments involving the effects of sulfonation and the presence of glucose units on the differentiation of mesenchymal stem cells. In Chapter 3, I utilize a heparin-mimetic PA to increase the survival of pancreatic islets transplanted into the rat omentum, and demonstrate that increased angiogenesis results in enhanced survival. Lastly, in Chapter 4, I summarize my results and describe the course of future experiments for the artificial regeneration of tissues through peptide amphiphile networks.
Open Access
Wavelet merged multi-resolution super-pixels and their applications on fluorescent MSC images
(IEEE, 2015) Yorulmaz, Onur; Oğuz, Oğuzhan; Akhan, Ece; Tuncel, Dönüş; Atalay, R. Ç.; Çetin, A. Enis
A new multi-resolution super-pixel based algorithm is proposed to track cell size, count and motion in Mesenchymal Stem Cells (MSCs) images. Multi-resolution super-pixels are obtained by placing varying density seeds on the image. The density of the seeds are determined according to the local high frequency components of the MSCs image. In this way a multi-resolution super-pixels decomposition of the image is obtained. A second contribution of the paper is novel decision rule for merging similar neighboring super-pixels. An algorithm based on well known wavelet decomposition is developed and applied to the histograms of neighboring super pixels to exploit similarity. The proposed algorithm is experimentally shown to be successful in segmenting and tracking cells in MSCs images.