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Shin Y.M.,Hanyang University | Park H.,Chung - Ang University | Shin H.,Hanyang University | Shin H.,Institute for Bioengineering and Biopharmaceutical Research
Macromolecular Research

A variety of surface modification techniques have been proposed to improve the cell-biomaterial interactions. On the other hand, these processes may cleave long-chained polymers, and compromise their mechanical properties. In this study, dopamine was used as a bridge molecule to immobilize gelatin on the poly(L-lactide-co-ω- caprolactone) (PLCL) fibrous matrices, which may then be used as a cell delivery carrier. The PLCL fibrous matrices coated with polydopamine by dipping (D-PLCL) can subsequently immobilize gelatin (GD-PLCL). The D-PLCL matrices showed minimal changes in the mechanical properties with a tensile strain of 251.0±33.4% and 247.8±32.1% before and after the coating process, respectively. The cellular activities on the fibrous matrices increased in the order of PLCL Source

Lee J.-H.,Hanyang University | Lee Y.-B.,Hanyang University | Rim N.-G.,Hanyang University | Jo S.-Y.,Korea Atomic Energy Research Institute | And 3 more authors.
Macromolecular Research

Poly(lactic-co-glycolic acid)(PLGA)/biphasic calcium phosphate (BCP) composite nanofibers with different BCP to PLGA ratios were fabricated using the electrospinning technique. The scanning electron microscopy (SEM) images showed a similar morphology and fibers in all groups. The incorporated BCP was dispersed homogenously throughout the nanofibers, and the surface roughness was affected by the input amount of BCP. The increase in amount of BCP incorporated was confirmed by several methods. BCP incorporation into the PLGA nanofibers did not affect the initial adhesion of osteoblasts and their adherent morphology. However, the proliferation of the cells cultured on the composite nanofibers for 10 days with larger amounts of BCP was delayed, suggesting that incorporated BCP may facilitate the switch from proliferation to differentiation of the osteoblasts. The incorporation of BCP enhanced the expression of osteogenic genes, as well as induced calcium deposition by the osteoblasts in the extracellular matrix(ECM) after 21 days of culture on the PLGA/BCP composite nanofibers. Overall, these results can provide evidence of the potential of BCP incorporation into the biomaterials for effective bone regeneration. © 2011 The Polymer Society of Korea and Springer Netherlands. Source

Rim N.G.,Hanyang University | Shin C.S.,Sogang University | Shin H.,Hanyang University | Shin H.,Institute for Bioengineering and Biopharmaceutical Research
Biomedical Materials (Bristol)

The ultimate goal of tissue engineering is to replace damaged tissues by applying engineering technology and the principles of life sciences. To successfully engineer a desirable tissue, three main elements of cells, scaffolds and growth factors need to be harmonized. Biomaterial-based scaffolds serve as a critical platform both to support cell adhesion and to deliver growth factors. Various methods of fabricating scaffolds have been investigated. One recently developed method that is growing in popularity is called electrospinning. Electrospinning is known for its capacity to make fibrous and porous structures that are similar to natural extracellular matrix (ECM). Other advantages to electrospinning include its ability to create relatively large surface to volume ratios, its ability to control fiber size from micro- to nano-scales and its versatility in material choice. Although early work with electrospun fibers has shown promise in the regeneration of certain types of tissues, further modification of their chemical, biological and mechanical properties would permit future advancements. In this paper, current approaches to the development of modular electrospun fibers as scaffolds for tissue engineering are discussed. Their chemical and physical characteristics can be tuned for the regeneration of specific target tissues by co-spinning of multiple materials and by post-modification of the surface of electrospun fibers. In addition, topology or structure can also be controlled to elicit specific responses from cells and tissues. The selection of proper polymers, suitable surface modification techniques and the control of the dimension and arrangement of the fibrous structure of electrospun fibers can offer versatility and tissue specificity, and therefore provide a blueprint for specific tissue engineering applications. © 2013 IOP Publishing Ltd. Source

Park J.-B.,Seoul National University of Science and Technology | Jeong J.-H.,Seoul National University | Lee M.,Institute for Bioengineering and Biopharmaceutical Research | Lee D.Y.,Institute for Bioengineering and Biopharmaceutical Research | And 2 more authors.
Journal of Biomaterials Science, Polymer Edition

This study proposed that microencapsulation of exendin-4 gene transduced islets using alginate, poly-L-lysine, and polyethylene glycol could lead to increased viability and functionality of islets in a rat to mouse xenograft model. The stability of the microcapsules was determined using an osmotic pressure test and a rotational stress test. Exendin-4 gene was transduced into pancreatic islets using lenti-viral vectors and the transduced islets were encapsulated using multi-component microcapsules mentioned above. Both viability and functionality of microencapsulated islets were evaluated in both in vitro and in vivo xenograft model. The viabilities of the unmodified islets (control) and the exendin-4 transduced islets (test) on 14th day were 18.6 ± 11.1 and 49.2 ± 13.4%, respectively (p < 0.05). The stimulation index of the control and the test groups was 2.3 ± 1.7 and 3.0 ± 1.6, respectively. The mean survival times (MST) of the control and the test groups were 20.2 ± 8.0 and 35.2 ± 10.0 days, respectively (p < 0.05). Significant differences in MST suggested that transduction of exendin-4 gene had a great potential to increase the function of encapsulated islets. In conclusion, exendin-4 gene transduced islets encapsulated by poly(ethylene glycol) conjugated alginate/PLL microcapsules significantly improved both viability and functionality of encapsulated islets. © 2013 © 2013 Taylor & Francis. Source

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