Papers by Author: B. Obradović

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Authors: B. Obradović, A. Osmokrović, B. Bugarski, D. Bugarski, G. Vunjak-Novaković
Abstract: Alginate was shown to be a suitable support for entrapment and cultivation of chondrocytes and bone marrow stromal cells, which under appropriate in vitro conditions synthesized cartilaginous components. The main limitation in these cultures may be low rates of mass transport through the alginate matrix governed by diffusion. In this study, we have designed and utilized a bioreactor system based on a packed bed of alginate beads with immobilized chondrogenic cells. Continuous medium perfusion provided convective mass transport through the packed bed, while small diameters of beads (2.5 mm and down to 500 μm) ensured short diffusion distances to the immobilized cells. During up to 5 weeks of cultivation, the cells synthesized extracellular matrix components merging beads together and indicating potentials of this system for precise regulation of the cellular microenvironment in cartilage tissue engineering.
Authors: D. Bugarski, B. Obradović, M. Petakov, G. Jovčić, N. Stojanović, B. Bugarski
Abstract: Alginate is currently being employed and explored for a broad range of biomedical and biotechnology applications, due to its biodegradability and simple procedure for cell immobilization. However, cell immobilization was mostly aimed for immunoisolatory and biochemical processing applications and far less is known about potentials of alginate as a substrate for tissue formation. In the present work, isolation, immobilization and cultivation procedures of murine bone marrow stromal cells (BMSC) were studied and standardized in order to establish the alginate-bioreactor culture system for chondrogenic and/or hematopoiesis-supportive tissue progression. Two techniques for cell immobilization based on alginate were investigated: entrapment within gel matrix using electrostatic droplet generation and simple cell adsorption onto gel surfaces. Alginate gels in forms of microbeads and discs with immobilized culture expanded BMSC were cultivated for up to 30 days and analyzed for surface properties, cell concentration, viability, and differentiation.
Authors: B. Obradović, D. Bugarski, M. Petakov, G. Jovčić, N. Stojanović, B. Bugarski, G. Vunjak-Novaković
Authors: B. Obradović, B. Bugarski, Z. Todosijević, V. Nedović, D. Bugarski, G. Vunjak-Novaković
Abstract: Alginate is one of the mostly used hydrogels for cell entrapment aimed for applications in food industry, environmental engineering, pharmacy and biomedicine. One of the major parameters affecting cell viability and activity is cell distribution inside the immobilization matrix. In addition, changes in cell distribution over the cultivation time could indicate mass transfer limitations, favorable local environments or cell differentiation. In this study, immobilization and distribution of brewing yeast in alginate microbeads were investigated as a model system of colony forming cell growth. Cell distributions were attained by image analysis of histological cross sections of microbeads used in beer fermentation. A mathematical model based on cellular automata approach was developed for three-dimensional simulations of cell arrangement over the fermentation time.
Authors: B. Obradović, I. Martin, L.E. Freed, G. Vunjak-Novaković
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