Controlled Release of Oxygen from PLGA-Alginate Layered Matrix and its In Vitro Characterization on the Viability of Muscle Cells under Hypoxic Environment

Syed Izhar Haider Abdi,최정연,Hui Chong Lau,임정옥 한국조직공학과 재생의학회 2013 조직공학과 재생의학 Vol.10 No.3

Coagulative necrosis often occurs under hypoxic conditions, causing major limitation in the field of tissue engineering especially those dealing with larger tissues and organs. In this study, a comprehensive work has been performed in developing a tailor made design of a dual layered matrix that can produce oxygen to be utilized in tissue engineering application. Optimizations of protocol, ingredient and condition of the system were carried out specifically based on the responses observed from in vitro studies using L6 rat skeletal muscle cell as a candidate. Oxygen was generated from decomposition of encapsulated hydrogen peroxide. Poly (D,L)-lactide-co-glycolide (PLGA)with molecular weights of 90,000 and 110,000 gmol-1 managed to secure good encapsulation of hydrogen peroxide for this application, while the best stirring time during the encapsulation was found to be 8 hours. The PLGA microspheres were coated with a secondary layer of alginate that was pre-grafted with calatase to form the dual layer system. This dual layered architecture has successfully controlled the release rate of oxygen at an optimum level for the survival of muscle cells under hypoxia condition. It was found that muscle cells have low tolerance limit towards the direct contact with hydrogen peroxide, however the cells maintained high viability within encapsulated hydrogen peroxide in the matrix system. It was observed that 4% of encapsulated hydrogen peroxide in the matrix system can produce efficient amount of oxygen at a controlled release manner to sustain the survival of muscle cells under hypoxic condition.

Size-controlled Microbeads through the Influence of the Coalescence Effect in the Emulsification Solvent Evaporation Method

Syed Izhar Haider Abdi,Sing Muk Ng,최정연,서지민,임정옥 한국고분자학회 2010 Macromolecular Research Vol.18 No.7

This paper reports a novel, simple, repeatable and cost-effective protocol for producing Ca-alginate beads with controlled sizes ranging from 50-250 μm with a narrow size distribution. The characteristics of the beads depend on the emulsion droplets formed, and the size of the beads can be controlled by manipulating the coalescence factor and the applied mechanical energy, which will also reduce the cost and overall time of the procedure. These results suggest that beads with diameters of 58±5, 69±7, 80±8, 145±11, 195±12 and 225±15 μm (mean diameter ±standard deviation) were easily produced. This was achieved simply by adding a minor amount of Pluronic F-127(i.e., 0.03%) and controlling the coalescence effect to reduce the stabilization of the emulsion. Therefore, the method has strong potential for mass production on an industrial scale. Furthermore, the solvent evaporation technique successfully evaporated the volatile organic solvent used for emulsification. The beads were proven to be safe via a cell culture study and might be suitable for use in the medical, pharmaceutical and bioengineering field.

In Vivo Study of a Blended Hydrogel Composed of Pluronic F-127-Alginate-Hyaluronic Acid for its Cell Injection Application

Syed Izhar Haider Abdi,최정연,이지선,임현주,이창호,김지현,정호윤,임정옥 한국조직공학과 재생의학회 2012 조직공학과 재생의학 Vol.9 No.1

The epitome that cell carrier serves solely as passive vehicles has become outdated. It is now evident that the carrier microenvironment also contributes in the regeneration process. In this study, a combination of alginate,pluronic F127 and extracellular matrix (ECM) component, hyaluronic acid (HA) based scaffold has been prepared for in situ gelling vehicles for muscle cells. ECM incorporated blended hydrogel showed enhanced uniform distribution of muscle cells in a nude mouse model forming the scaffold in situ allowed the muscle cells to proliferate efficiently, indicating that a pluronic F127/alginate/HA matrix provided a beneficial environment for cellular growth and expansion. The formation of gel beneath the skin of nude mice was confirmed using optical coherence tomography (OCT). OCT has been used to visualize the in situ localization of cells as well. This in situ gelation is found to be advantageous for regenerative applications due to the absence of toxic solvents or co-polymerization agents;besides the handling process is simple. This study demonstrates that an in situ blended hydrogels enables the favorable settlement of cells and satisfactory cell delivery for muscle regeneration applications.

pH-Sensitive nanocargo based on smart polymer functionalized graphene oxide for site-specific drug delivery

Kavitha, Thangavelu,Haider Abdi, Syed Izhar,Park, Soo-Young The Royal Society of Chemistry 2013 Physical chemistry chemical physics Vol.15 No.14

<P>Graphene oxide (GO) was functionalized covalently with pH-sensitive poly(2-(diethylamino) ethyl methacrylate) (PDEA) by surface-initiated <I>in situ</I> atom transfer radical polymerization. The structure of the PDEA-grafted GO (GO-PDEA) were examined by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and atomic force microscopy. The grafted PDEA endowed the GO sheets with good solubility and stability in physiological solutions. Simple physisorption by π–π stacking and hydrophobic interactions on GO-PDEA can be used to load camptothecin (CPT), a widely used water-insoluble cancer drug. The loaded CPT was released only at the lower (acidic) pH normally found in a tumor environment but not in basic and neutral pH. GO-PDEA did not show practical toxicity to N2a cancer cells but the GO-PDEA-CPT complex exhibited high potency in killing N2a cancer cells <I>in vitro</I>. These results suggest that the GO-PDEA nanocargo carrier might be a promising material for site-specific anticancer drug delivery and controlled release.</P> <P>Graphic Abstract</P><P>PDEA-grafted graphene oxide is a promising material for site-specific anticancer drug delivery and controlled release. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cp00008g'> </P>

In Vitro 주사형 Poly (ε-caprolactone)-Pluronic F127 (PCL-Pluronic) 하이드로젤의 생체적합성 평가

최정연,임현주,Syed Izhar Haider Abdi,정호윤,임정옥 한국조직공학과 재생의학회 2011 조직공학과 재생의학 Vol.8 No.1s

Thermosensitive hydrogels based on synthetic block copolymers have gained increasing attention due to their in-situ forming characteristics for various applications including controlled drug delivery, cell encapsulation and tissue regeneration. In this study, a series of biodegradable hydrogels which are the block Poly (ε-caprolactone)-Pluronic F127(PCL-Pluronic) copolymers were synthesized by ring-opening polymerization, and were characterized by 1H NMR, FTIR,GPC, and TA-DSC. Sol-gel phase transition diagrams were recorded using test tube inverting method. Temperature dependent sol-gel phase transition depended on hydrophilic/hydrophobic balance in macromolecular structure. The biocompatibility of these hydrogels was evaluated using cytotoxicity assays with human amniotic fluid stem cells. The properties of the PCL-Pluronic hydrogels demonstrated to be thermosensitive, biodegradable and biocompatible, which would enable the application of cell therapy and tissue regeneration.

Fabrication and Characterization of Epithelial Scaffolds for Hair Follicle Regeneration

( Ji Won Oh ),( Jeong Yeon Choi ),( Min Ji Kim ),( Syed Izhar Haider Abdi ),( Hui Chong Lau ),( Moon Kyu Kim ),( Jeong Ok Lim ) 한국조직공학·재생의학회 2012 조직공학과 재생의학 Vol.9 No.3

The field of hair follicle regeneration is advancing rapidly, and there have been a number of major achievements over the last decade. Nonetheless, most of the current technologies are still unable to maintain their in vivo characteristics in vitro. The formation of new hair follicles for the treatment of alopecia using tissue engineering technology is promising; however, little or no work has been attempted in this area so far. In order to enhance the hair inducing ability of epithelial cells and to form the functional epithelial structure, we attempted to fabricate threedimensional scaffolds by using bladder submucosal membrane (BSM), keratin, hyaluronic acid (HA), and mouse newborn epithelial skin scaffold (NESS). We characterized their properties with respect to the formation of the epithelial structure. The BSM sponge demonstrated the intrinsic activation of melanocytes once we inserted the inductive dermal papilla sphere. We found that the fiber sheet made of keratin enhanced cell spreading and adhesion better than the sheet with HA. The human outer root sheath keratinocytes formed a cluster on the NESS. These scaffolds would be used for the follicular epithelial cell physiology and study for property of them in vitro. This study demonstrated the potential of epithelial cell scaffolds for effective hair regeneration.