Kyu Sik Shim

Fabrication of a BMP-2-immobilized porous microsphere modified by heparin for bone tissue engineering.

The purpose of this study was to fabricate BMP-2-immobilized porous poly(lactide-co-glycolide) (PLGA) microspheres (PMS) modified with heparin for bone regeneration. A fluidic device was used to fabricate PMS and the fabricated PMS was modified with heparin-dopamine (Hep-DOPA). Bone morphogenic protein-2 (BMP-2) was immobilized on the heparinized PMS (Hep-PMS) via electrostatic interactions. Both PMS and modified PMS were characterized using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). MG-63 cell activity on PMS and modified PMS were assessed via alkaline phosphatase (ALP) activity, calcium deposition, and osteocalcin and osteopontin mRNA expression. Immobilized Hep-DOPA and BMP-2 on PMS were demonstrated by XPS analysis. BMP-2-immobilized Hep-PMS provided significantly higher ALP activity, calcium deposition, and osteocalcin and osteopontin mRNA expression compared to PMS alone. These results suggest that BMP-2-immobilized Hep-PMS effectively improves MG-63 cell activity. In conclusion, BMP-2-immobilized Hep-PMS can be used to effectively regenerate bone defects.

Effect of lactoferrin-impregnated porous poly(lactide-co-glycolide) (PLGA) microspheres on osteogenic differentiation of rabbit adipose-derived stem cells (rADSCs).

The aim of this study was to develop lactoferrin (LF)-impregnated porous poly(lactide-co-glycolide) (PLGA) microspheres (PMs) to induce osteogenic differentiation of rabbit adipose-derived stem cells (rADSCs). Porous PLGA PMs were fabricated by a fluidic device and their surfaces were modified with heparin-dopamine (Hep-DOPA). Then, LF (100μg, 500μg, and 1000μg) was impregnated on the surface of heparinized PMs (Hep-PMs) via electrostatic interactions to yield LF-impregnated PMs. PMs and modified PMs were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Osteogenic differentiation of rADSCs on PMs and modified PMs was demonstrated by alkaline phosphatase (ALP) activity, calcium deposition, and mRNA expression of osteocalcin and osteopontin. Successful immobilization of Hep-DOPA and LF on the surface of PMs was confirmed by XPS analysis. LF-impregnated PMs generated significantly greater ALP activity, calcium deposition, and mRNA expression of osteocalcin and osteopontin compared with PMs. These results suggested that LF-impregnated PMs effectively induced osteogenic differentiation of rADSCs.

3D printed alendronate-releasing poly(caprolactone) porous scaffolds enhance osteogenic differentiation and bone formation in rat tibial defects.

The aim of this study was to evaluate the in vitro osteogenic effects and in vivo new bone formation of three-dimensional (3D) printed alendronate (Aln)-releasing poly(caprolactone) (PCL) (Aln/PCL) scaffolds in rat tibial defect models. 3D printed Aln/PCL scaffolds were fabricated via layer-by-layer deposition. The fabricated Aln/PCL scaffolds had high porosity and an interconnected pore structure and showed sustained Aln release. In vitro studies showed that MG-63 cells seeded on the Aln/PCL scaffolds displayed increased alkaline phosphatase (ALP) activity and calcium content in a dose-dependent manner when compared with cell cultures in PCL scaffolds. In addition, in vivo animal studies and histologic evaluation showed that Aln/PCL scaffolds implanted in a rat tibial defect model markedly increased new bone formation and mineralized bone tissues in a dose-dependent manner compared to PCL-only scaffolds. Our results show that 3D printed Aln/PCL scaffolds are promising templates for bone tissue engineering applications.

Heparin-immobilized hydroxyapatite nanoparticles as a lactoferrin delivery system for improving osteogenic differentiation of adipose-derived stem cells

The aim of this study is to fabricate lactoferrin (LF)-carrying hydroxyapatite nanoparticles (HAp NPs) to enhance osteogenic differentiation of rabbit adipose-derived stem cells (rADSCs). HAp NPs were modified with heparin-dopamine (Hep-DOPA) (Hep-HAp) and further immobilized with LF (LF/Hep-HAp). Heparin immobilization on HAp NPs prevented aggregation of HAp NPs in aqueous solution and prolonged the release of LF from LF/Hep-HAp NPs. In vitro studies of rADSCs have demonstrated that LF-Hep/HAp NPs significantly increase alkaline phosphatase (ALP) activity, calcium deposition, and both mRNA expression of osteocalcin (OCN) and osteopontin (OPN) in comparison with HAp and Hep-HAp NPs. These results suggest that LF/Hep-HAp NPs can effectively induce osteogenic differentiation of rADSCs.

Exploring the In Vivo Anti-Inflammatory Actions of Simvastatin-Loaded Porous Microspheres on Inflamed Tenocytes in a Collagenase-Induced Animal Model of Achilles Tendinitis

Tendon rupture induces an inflammatory response characterized by release of pro-inflammatory cytokines and impaired tendon performance. This study sought to investigate the therapeutic effects of simvastatin-loaded porous microspheres (SIM/PMSs) on inflamed tenocytes in vitro and collagenase-induced Achilles tendinitis in vivo. The treatment of SIM/PMSs in lipopolysaccharide (LPS)-treated tenocytes reduced the mRNA expressions of pro-inflammatory cytokines (Matrix metalloproteinase-3 (MMP-3), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α)). In addition, the local injection of SIM/PMSs into the tendons of collagenase-induced Achilles tendinitis rat models suppressed pro-inflammatory cytokines (MMP-3, COX-2, IL-6, TNF-α, and MMP-13). This local treatment also upregulated anti-inflammatory cytokines (IL-4, IL-10, and IL-13). Furthermore, treatment with SIM/PMSs also improved the alignment of collagen fibrils and effectively prevented collagen disruption in a dose-dependent manner. Therefore, SIM/PMSs treatment resulted in an incremental increase in the collagen content, stiffness, and tensile strength in tendons. This study suggests that SIM/PMSs have great potential for tendon healing and restoration in Achilles tendinitis.

Attenuation of inflammation and cartilage degradation by sulfasalazine-containing hyaluronic acid on osteoarthritis rat model

The aim of this study was to investigate the effects of a sulfasalazine-containing hyaluronic acid (SASP/HA) systems on in vitro anti-inflammation and the alleviation of cartilage degradation in both lipopolysaccharide (LPS)-stimulated synoviocytes and a rat model of monosodium iodoacetate (MIA)-induced osteoarthritis (OA). The SASP/HA resulted in long-term release of SASP from the SASP/HA for up to 60 days in a sustained manner. In vitro studies performed using real-time polymerase chain reaction (PCR) assay revealed that the SASP/HA was able to effectively and dose-dependently inhibit the mRNA expression levels of pro-inflammatory cytokines such as matrix metalloproteinases-3 (MMP-3), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in LPS-stimulated synoviocytes. In vivo studies showed that intra articular injection of SASP/HA greatly reduced the MIA-stimulated mRNA expression of MMP-3, COX-2, IL-6, and TNF-α in blood. Furthermore, these significant anti-inflammatory effects of SASP/HA contributed markedly to the alleviation of progression of MIA-induced OA and cartilage degradation, as demonstrated by X-ray, micro-computed tomography (micro-CT), gross findings, and histological evaluations. Therefore, our findings indicated that the long-term and sustained delivery of SASP using HA can play a therapeutic role in alleviating inflammation as well as protecting against cartilage damage in OA.

Biphasic Calcium Phosphate (BCP)-Immobilized Porous Poly (d,l-Lactic-co-Glycolic Acid) Microspheres Enhance Osteogenic Activities of Osteoblasts

The purpose of this study was to evaluate the potential of porous poly (d,l-lactic-co-glycolic acid) (PLGA) microspheres (PMSs) immobilized on biphasic calcium phosphate nanoparticles (BCP NPs) (BCP-IM-PMSs) to enhance osteogenic activity. PMSs were fabricated using a fluidic device, and their surfaces were modified with l-lysine (aminated-PMSs), whereas the BCP NPs were modified with heparin–dopamine (Hep-DOPA) to obtain heparinized–BCP (Hep-BCP) NPs. BCP-IM-PMSs were fabricated via electrostatic interactions between the Hep-BCP NPs and aminated-PMSs. The fabricated BCP-IM-PMSs showed an interconnected pore structure. In vitro studies showed that MG-63 cells cultured on BCP-IM-PMSs had increased alkaline phosphatase activity, calcium content, and mRNA expression of osteocalcin (OCN) and osteopontin (OPN) compared with cells cultured on PMSs. These data suggest that BCP NP-immobilized PMSs have the potential to enhance osteogenic activity.