Development of a dual growth factor loaded biodegradable hydrogel and its evaluation on osteoblast differentiation in vi
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Development of a dual growth factor loaded biodegradable hydrogel and its evaluation on osteoblast differentiation in vitro Deepti Dyondi 1,2, Thomas J Webster 2 and Rinti Banerjee 1 1
Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay,
Mumbai 400076, Maharashtra, India. 2
School of Engineering and Department of Orthopedics, Brown University, Providence 02906,
RI, United States. ABSTRACT Hydrogels with their tunable properties are attractive candidates for developing tissue engineering scaffolds for various applications (including bone and cartilage). The current work involved studying the synergistic effect of basic fibroblast growth factor (bFGF) and platelet derived growth factor BB (PDGF-BB) entrapped within injectable porous gels for bone regeneration applications. An in situ gelling system was developed using bacterial polysaccharides gellan and xanthan gum by temperature and ionic gelation with Ca+2. After the initial characterization of the hydrogels, a dual growth factor release system was developed wherein growth factors were encapsulated within chitosan nanoparticles embedded in the gels as well as directly within the gel. The hydrogel structure was characterized by SEM and TEM and in vitro growth factor release studies showed a slow release profile in PBS. Further, human fetal osteoblasts were entrapped within the hydrogel and a 21 day osteoblast differentiation study was conducted. An improvement in osteoblast total protein synthesis and collagen content was observed by day 21 compared to control gels without growth factors. Although further evaluation regarding mechanical properties and expression of osteogenic differentiation marker genes will be necessary, the present study suggests that injectable scaffolds can be used for the delivery of multiple growth promoting agents to support osteoblast differentiation. INTRODUCTION With its ability to deliver osteoconductive as well as osteoinductive (such as growth factors and cytokines) materials to the defect site [1], bone tissue engineering has emerged as a promising alternative to the currently available bone restoration methods (autografts, allografts etc) that offer several complications of undesirable tissue response and increased risk of infection at the implant site. The use of biodegradable polymers (such as hydrogels) allows for a great deal of flexibility with respect to their tunable mechanical properties and natural degradation times within the body. The polymer system could be tuned to gel within the body thus entrapping molecules for delivery to the bone defect site including stem cells, growth factors, drug molecules and recombinant proteins [2, 3].
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The current study explores natural polymers namely gellan and xanthan for developing a nanoparticulate in situ gelling system which along with cells and growth factors may be delivered at the defect site. Gellan gum, an anionic exocellular polysaccharide derived from the bacteria Sphingomonas elodea, in combination with hyaluronic acid, in the presence
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