Sung-Jun An

The effect of bacterial cellulose membrane compared with collagen membrane on guided bone regeneration

PURPOSE This study was to evaluate the effects of bacterial cellulose (BC) membranes as a barrier membrane on guided bone regeneration (GBR) in comparison with those of the resorbable collagen membranes. MATERIALS AND METHODS BC membranes were fabricated using biomimetic technology. Surface properties were analyzed, Mechanical properties were measured, in vitro cell proliferation test were performed with NIH3T3 cells and in vivo study were performed with rat calvarial defect and histomorphometric analysis was done. The Mann-Whitney U test and the Wilcoxon signed rank test was used (α<.05). RESULTS BC membrane showed significantly higher mechanical properties such as wet tensile strength than collagen membrane and represented a three-dimensional multilayered structure cross-linked by nano-fibers with 60 % porosity. In vitro study, cell adhesion and proliferation were observed on BC membrane. However, morphology of the cells was found to be less differentiated, and the cell proliferation rate was lower than those of the cells on collagen membrane. In vivo study, the grafted BC membrane did not induce inflammatory response, and maintained adequate space for bone regeneration. An amount of new bone formation in defect region loaded with BC membrane was significantly similar to that of collagen membrane application. CONCLUSION BC membrane has potential to be used as a barrier membrane, and efficacy of the membrane on GBR is comparable to that of collagen membrane.

Promotion of human mesenchymal stem cell differentiation on bioresorbable polycaprolactone/biphasic calcium phosphate composite scaffolds for bone tissue engineering

An artificial construct mimicking the intrinsic properties of the natural extracellular matrix in bones has been considered an ideal platform for bone tissue engineering, as it can present an appropriate microenvironment and regulate cell behaviours. In this report, we introduce biodegradable composite scaffolds consisting of polycaprolactone (PCL) and biphasic calcium phosphate (BCP). The scaffolds were fabricated by a salt-leaching process, and the ability of the scaffolds to facilitate osteogenic differentiation was investigated using human mesenchymal stem cells (hMSCs). The scaffolds had an inter-connected porous structure with quadrilateral pores of approximately 200 ∼ 500 μm in width. The mechanical properties of the scaffolds changed as the BCP content was increased in the starting mixture. In the hMSC experiment, although we found that hMSCs adhered to the surface, as well as the inside, of the scaffolds, the incorporated BCP did not increase the proliferation of the hMSCs over 7 days in culture. Interestingly, the alkaline phosphatase (ALP) activity was 4 times higher on the PCL/BCP composite scaffold (0.12 ± 0.03 nmol/min/μg protein) thanon the PCL scaffold (0.03 ± 0.01 nmol/min/μg protein), suggesting that BCP can aid in generating a local environment that promotes bone regeneration. Therefore, a strategy combining polymers and ceramics can be considered a useful platform for bone tissue engineering.

The Effect of Thickness of Resorbable Bacterial Cellulose Membrane on Guided Bone Regeneration

This study introduces the effect of the thickness of a bacterial cellulose membrane by comparing the bone regeneration effect on rat skulls when using a collagen membrane and different thicknesses of resorbable bacterial cellulose membranes for guided bone regeneration. Barrier membranes of 0.10 mm, 0.15 mm, and 0.20 mm in thickness were made using bacterial cellulose produced as microbial fermentation metabolites. Mechanical strength was investigated, and new bone formation was evaluated through animal experimental studies. Experimental animals were sacrificed after having 2 weeks and 8 weeks of recovery, and specimens were processed for histologic and histomorphometric analyses measuring the area of bone regeneration (%) using an image analysis program. In 2 weeks, bone-like materials and fibrous connective tissues were observed in histologic analysis. In 8 weeks, all experimental groups showed the arrangement of osteoblasts surrounding the supporting body on the margin and center of the bone defect region. However, the amount of new bone formation was significantly higher (p < 0.05) in bacterial cellulose membrane with 0.10 mm in thickness compared to the other experimental groups. Within the limitations of this study, a bacterial cellulose membrane with 0.10 mm thickness induced the most effective bone regeneration.

The Efficacy of Electron Beam Irradiated Bacterial Cellulose Membranes as Compared with Collagen Membranes on Guided Bone Regeneration in Peri-Implant Bone Defects

Bacterial cellulose (BC) is a natural polysaccharide produced by some bacteria, and consists of a linear polymer linked by β-(1,4) glycosidic bonds. BC has been developed as a material for tissue regeneration purposes. This study was conducted to evaluate the efficacy of resorbable electron beam irradiated BC membranes (EI-BCMs) for guided bone regeneration (GBR). The electron beam irradiation (EI) was introduced to control the biodegradability of BC for dental applications. EI-BCMs had higher porosity than collagen membranes (CMs), and had similar wet tensile strengths to CMs. NIH3T3 cell adhesion and proliferation on EI-BCMs were not significantly different from those on CMs (p > 0.05). Micro-computed tomography (μCT) and histometric analysis in peri-implant dehiscence defects of beagle dogs showed that EI-BCMs were non-significantly different from CMs in terms of new bone area (NBA; %), remaining bone substitute volume (RBA; %) and bone-to-implant contact (BIC; %) (p > 0.05). These results suggest resorbable EI-BCMs can be used as an alternative biomaterial for bone tissue regeneration.

Physicochemical characterization of gelatin-immobilized, acrylic acid-bacterial cellulose nanofibers as cell scaffolds using gamma-irradiation

Bacterial cellulose (BC) has been shown to have a high-burst pressure, high-water contact, and ultrafine highly nanofibrous structure similar with that in a natural extracellular matrix (ECM). In the present study, we developed a BC-based functional scaffold for tissue engineering using radiation technology. BC was generated by Gluconacetobacter hansenii TL-2C. Acrylic acid (AAc) was grafted onto BC surfaces under aqueous conditions using gamma-ray irradiation. The characterization of the scaffold was performed by scanning electron microscopy, ATR-FTIR spectroscopy, a toluidine blue O assay, and 2,4,6,-trinitro-benzensulfonic acid assay. AAc was grafted on the BC under gamma-ray irradiation. Gelatin was chemically conjugated on the AAc-BC scaffolds through EDC chemistry. The morphology of the modified BC nanofibers did not change, while representative features of AAc and gelatin were maintained. The adhesion and spreading of human mesenchymal stem cells was improved on the gelatin-AAc-BC nanofibers compared to unmodified BC and AAc-BC nanofibers. Our results suggest that gelatin-immobilized BC nanofiber scaffolds can be a promising way to fabricate three-dimentional, nanofibrous scaffolds that accelerate cell behavior for biomedical applications.

Chestnut Honey Impregnated Carboxymethyl Cellulose Hydrogel for Diabetic Ulcer Healing

Honey-based wound dressings have attracted a lot of attention from modern scientists owing to their anti-inflammatory and antibacterial effects without antibiotic resistance. Such dressings also promote moist wound healing, and have been considered natural, abundant, and cheap materials for folk marketing. This study investigated the various behaviors and characteristics of chestnut honey-impregnated carboxymethyl cellulose sodium hydrogel paste (CH–CMC) as a therapeutic dressing, such as its moist retention, antibacterial activity for inhibiting the growth of Staphylococcus aureus and Escherichia coli, and the rate of wound healing in db/db mice. The results provide good evidence, suggesting that CH–CMC has potential as a competitive candidate for diabetic ulcer wound healing.

Preparation and Characterization of Resorbable Bacterial Cellulose Membranes Treated by Electron Beam Irradiation for Guided Bone Regeneration

Bacterial cellulose (BC) is an excellent biomaterial with many medical applications. In this study, resorbable BC membranes were prepared for guided bone regeneration (GBR) using an irradiation technique for applications in the dental field. Electron beam irradiation (EI) increases biodegradation by severing the glucose bonds of BC. BC membranes irradiated at 100 kGy or 300 kGy were used to determine optimal electron beam doses. Electron beam irradiated BC membranes (EI-BCMs) were evaluated by scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, thermal gravimetric analysis (TGA), and using wet tensile strength measurements. In addition, in vitro cell studies were conducted in order to confirm the cytocompatibility of EI-BCMs. Cell viabilities of NIH3T3 cells on 100k and 300k EI-BCMs (100 kGy and 300 kGy irradiated BC membranes) were significantly greater than on NI-BCMs after 3 and 7 days (p < 0.05). Bone regeneration by EI-BCMs and their biodegradabilities were also evaluated using in vivo rat calvarial defect models for 4 and 8 weeks. Histometric results showed 100k EI-BCMs exhibited significantly larger new bone area (NBA; %) than 300k EI-BCMs at 8 weeks after implantation (p < 0.05). Mechanical, chemical, and biological analyses showed EI-BCMs effectively interacted with cells and promoted bone regeneration.

Preparation and evaluation of β -glucan hydrogel prepared by the radiation technique for drug carrier applications

β-Glucan can provide excellent environment to apply to drug carrier due to its immunological and anti-inflammatory effect. Minocycline hydrochloride (MH) has excellent oral bioavailability pharmacological properties. Specifically, MH is effectively absorbed into the gingiva for periodontal disease treatment. In this study, we attempt to develop MH loaded β-glucan hydrogel for periodontal disease treatment through radiation-crosslinking technique. In addition, MH loaded β-glucan hydrogels were tested for their cytotoxicity and antibacterial activity. Finally, we conducted an in vivo study to demonstrate the potential to prevent the invasion of bacteria to treat periodontal disease. The gel content and compressive strength of the β-glucan hydrogels increased as the β-glucan content and the absorbed dose (up to 7 kGy) increased. For a radiation dose of 7 kGy, the gelation and the compressive strength of a 6 wt% β-glucan hydrogel were approximately 92% and 270 kPa, respectively. As a drug, MH was consistently released from β-glucan hydrogels, reaching 80% at approximately 90 min. Furthermore, the MH loaded β-glucan hydrogels showed no cytotoxicity. The MH loaded β-glucan hydrogels exhibited good antibacterial activity against Porphyromonas gingivalis. In addition, MH loaded β-glucan hydrogel demonstrated the potential of a good capability to prevent the invasion of bacteria and to treat wounds.