Biomedical subjects

Min Sun Park

Publications and source records attributed to Min Sun Park.

4 recordsLinked to original sources

PubMed2007

A poly(lactide-co-glycolide)/hydroxyapatite composite scaffold with enhanced osteoconductivity.

Biodegradable polymer/ceramic scaffolds can overcome the limitations of conventional ceramic bone substitutes. However, the conventional methods of polymer/ceramic scaffold fabrication often use organic solvents, which might be harmful to cells or tissues. Moreover, scaffolds fabricated with the conventional methods have limited ceramic exposure on the scaffold surface since the polymer solution envelopes the ceramic particles during the fabrication process. In this study, we developed a novel fabrication method for the efficient exposure of ceramic onto the scaffold surface, which would enhance the osteoconductivity and wettability of the scaffold. Poly(D,L-lactide-co-glycolide)/nanohydroxyapatite (PLGA/HA) scaffolds were fabricated by the gas foaming and particulate leaching (GF/PL) method without the use of organic solvents. Selective staining of ceramic particles indicated that HA nanoparticles exposed to the scaffold surface were observed more abundantly in the GF/PL scaffold than in the conventional solvent casting and particulate leaching (SC/PL) scaffold. Both types of scaffolds were implanted to critical size defects in rat skulls for 8 weeks. The GF/PL scaffolds exhibited significantly enhanced bone regeneration when compared with the SC/PL scaffolds. Histological analyses and microcomputed tomography of the regenerated tissues showed that bone formation was more extensive on the GF/PL scaffolds than on the SC/PL scaffolds. Compared with the SC/PL scaffolds, the enhanced bone formation on the GF/PL scaffolds may result from the higher exposure of HA nanoparticles to the scaffold surface. These results show that the biodegradable polymer/ceramic composite scaffolds fabricated with the novel GF/PL method can enhance bone regeneration compared with those fabricated with the conventional SC/PL method.

Absorbable Implants↗

PubMed2006

Enhancement of the osteogenic efficacy of osteoblast transplantation by the sustained delivery of basic fibroblast growth factor.

Previously, the sustained delivery of basic fibroblast growth factor (bFGF) has been demonstrated to promote bone regeneration in bone defects that had not been treated with osteogenic cell transplantation. In this study, we tested the hypothesis that the sustained delivery of bFGF could enhance osteoblast transplantation-mediated ectopic bone formation. Rat osteoblasts and bFGF were mixed with an injectable fibrin matrix and subcutaneously transplanted to rats (cell + bFGF group). The fibrin matrix played roles in both the cell transplantation matrix and the bFGF sustained delivery matrix. The transplantation of osteoblasts suspended in a fibrin matrix without bFGF served as a control. Twelve weeks after transplantation, histological analyses of retrieved transplants showed that new bone formation was more abundant and mature in the cell + bFGF group than in the control group. The bone formation area and the calcium content in the cell + bFGF group were two- and nine-fold higher, respectively, than those in the control group. Enhanced bone formation by the sustained delivery of bFGF may be attributed to the enhanced osteogenic gene expression of the transplanted cells and neovascularization of the transplants, as both mRNA expression of various osteogenic markers and arteriole density in the cell + bFGF group were significantly higher than those in the control group. This study demonstrates that the sustained delivery of bFGF can potentiate ectopic bone regeneration by osteoblast transplantation. This combination therapy may have effective implications for bone regeneration in large bone defects in which extensive osteogenic cell migration and angiogenesis are required.

Animals↗

PubMed2005

Poly(lactide-co-glycolide)/hydroxyapatite composite scaffolds for bone tissue engineering.

Biodegradable polymer/bioceramic composite scaffolds can overcome the limitations of conventional ceramic bone substitutes such as brittleness and difficulty in shaping. However, conventional methods for fabricating polymer/bioceramic composite scaffolds often use organic solvents (e.g., the solvent casting and particulate leaching (SC/PL) method), which might be harmful to cells or tissues. Furthermore, the polymer solutions may coat the ceramics and hinder their exposure to the scaffold surface, which may decrease the likelihood that the seeded osteogenic cells will make contact with the bioactive ceramics. In this study, a novel method for fabricating a polymer/nano-bioceramic composite scaffold with high exposure of the bioceramics to the scaffold surface was developed for efficient bone tissue engineering. Poly(D,L-lactic-co-glycolic acid)/nano-hydroxyapatite (PLGA/HA) composite scaffolds were fabricated by the gas forming and particulate leaching (GF/PL) method without the use of organic solvents. The GF/PL method exposed HA nanoparticles at the scaffold surface significantly more than the conventional SC/PL method does. The GF/PL scaffolds showed interconnected porous structures without a skin layer and exhibited superior enhanced mechanical properties to those of scaffolds fabricated by the SC/PL method. Both types of scaffolds were seeded with rat calvarial osteoblasts and cultured in vitro or were subcutaneously implanted into athymic mice for eight weeks. The GF/PL scaffolds exhibited significantly higher cell growth, alkaline phosphatase activity, and mineralization compared to the SC/PL scaffolds in vitro. Histological analyses and calcium content quantification of the regenerated tissues five and eight weeks after implantation showed that bone formation was more extensive on the GF/PL scaffolds than on the SC/PL scaffolds. Compared to the SC/PL scaffolds, the enhanced bone formation on the GF/PL scaffolds may have resulted from the higher exposure of HA nanoparticles at the scaffold surface, which allowed for direct contact with the transplanted cells and stimulated the cell proliferation and osteogenic differentiation. These results show that the biodegradable polymer/bioceramic composite scaffolds fabricated by the novel GF/PL method enhance bone regeneration compared with those fabricated by the conventional SC/PL method.

Alkaline Phosphatase↗

PubMedDate not supplied

Peritoneal ultrafiltration and serum icodextrin concentration during dialysis with 7.5% icodextrin solution in Japanese patients.

OBJECTIVES: To assess the efficacy and safety of icodextrin in Japanese patients and to investigate the relationship between net ultrafiltration (UF) during the long dwell and plasma oligosaccharides. DESIGN: Open-labeled clinical trial involving patients on continuous ambulatory peritoneal dialysis (CAPD) receiving icodextrin during the 12-hour long dwell for 6 weeks, preceded by and followed by a 2-week baseline period and a follow-up period during which 1.36% glucose was used for the 8-hour long dwell. SETTING: A prospective, randomized multicenter study done in tertiary medical centers. PATIENTS: 18 stable patients on CAPD for 3 months or longer. MAIN OUTCOMES MEASURES: Net UF (in milliliters), UF rate (in milliliters per hour), plasma oligosaccharides, serum osmolarity (in milliosmoles per liter), peritoneal absorption of icodextrin, and peritoneal clearances of icodextrin, creatinine, and urea were assessed. Adverse events, laboratory findings, and vital signs were also monitored. RESULTS: Long-dwell net UF (544.4 +/- 96.7 mL at day 3, p < 0.001; 309.4 +/- 60.7 mL at week 4, p < 0.001; and 391.7 +/- 61.1 mL at week 6, p < 0.001) and UF rate (48.2 +/- 38.8 mL/ hour at day 3, p < 0.001; 26.9 +/- 22.1 mL/hr at week 4, p < 0.002; and 35.3 +/- 22.9 mL/hr at week 6, p = 0.0002) were significantly greater during the icodextrin period than at baseline (-25.9 +/- 46.0 mL and -2.2 +/- 22.1 mL/hr, respectively). Plasma oligosaccharides reached steady state within 2 weeks, remained stable during the treatment period, and returned to baseline level 2 weeks after discontinuation of icodextrin. Serum osmolarity increased during the use of icodextrin by approximately 5 mOsm/L. No statistically significant relationship was found between plasma oligosaccharides and net UF. Peritoneal absorption of icodextrin (36.3% +/- 5.1% at day 3, 42.2% +/- 5.9% at week 4, and 38.0% +/- 6.3% at week 6) and peritoneal clearance of icodextrin (10.1 mL/minute at day 3, 10.1 mL/min at week 4, and 10.3 mL/min at week 6) showed no major change over time. Serum sodium and serum chloride both decreased by 5 mEq/L with icodextrin but remained within the normal range during the treatment period and returned to baseline levels immediately after discontinuation. No serious adverse events were observed during the study. CONCLUSION: The results of this study do not support the hypothesis that an increased blood oligosaccharide level and the concomitant elevation in serum osmolarity have a negative impact on peritoneal UF. Therefore, the increase in plasma oligosaccharides appears to be too small to be of clinical significance.

Dialysis Solutions↗