[Show abstract][Hide abstract] ABSTRACT: There has been a tremendous amount of research in the past decade to optimize the mechanical properties and degradation behavior of the biodegradable Mg alloy for orthopedic implant. Despite the feasibility of degrading implant, the lack of fundamental understanding about biocompatibility and underlying bone formation mechanism is currently limiting the use in clinical applications. Herein, we report the result of long-term clinical study and systematic investigation of bone formation mechanism of the biodegradable Mg-5wt%Ca-1wt%Zn alloy implant through simultaneous observation of changes in element composition and crystallinity within degrading interface at hierarchical levels. Controlled degradation of Mg-5wt%Ca-1wt%Zn alloy results in the formation of biomimicking calcification matrix at the degrading interface to initiate the bone formation process. This process facilitates early bone healing and allows the complete replacement of biodegradable Mg implant by the new bone within 1 y of implantation, as demonstrated in 53 cases of successful long-term clinical study.
Full-text · Article · Jan 2016 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: The aims of the present study were to determine the exact role of osteoclasts in the biodegradation of calcium phosphate ceramics of different solubilities, and to investigate the relationship between osteoclastic activity and extracellular Ca2+ concentration. Hydroxyapatite
(HA) and β-tricalcium phosphate (β-TCP) disks were incubated in culture medium, without cells, to evaluate chemical dissolution. On other disks, osteoclasts were cultured to analyze cell-mediated resorption. After 5 days, the area fraction resorbed by chemical dissolution
of β-TCP disks (54.3%) was significantly greater than that of HA disks (4.0%, p
No preview · Article · Oct 2014 · Journal of Applied Statistics
[Show abstract][Hide abstract] ABSTRACT: Crystalline Mg-based alloys with a distinct reduction in hydrogen evolution were prepared through both electrochemical and microstructural engineering of the constituent phases. The addition of Zn to Mg-Ca alloy modified the corrosion potentials of two constituent phases (Mg + Mg2Ca), which prevented the formation of a galvanic circuit and achieved a comparable corrosion rate to high purity Mg. Furthermore, effective grain refinement induced by the extrusion allowed the achievement of much lower corrosion rate than high purity Mg. Animal studies confirmed the large reduction in hydrogen evolution and revealed good tissue compatibility with increased bone deposition around the newly developed Mg alloy implants. Thus, high strength Mg-Ca-Zn alloys with medically acceptable corrosion rate were developed and showed great potential for use in a new generation of biodegradable implants.
Full-text · Article · Aug 2013 · Scientific Reports
[Show abstract][Hide abstract] ABSTRACT: This study was undertaken to generate and characterize human induced pluripotent stem cells (PSCs) from patients with osteoarthritis (OA) and to examine whether these cells can be developed into disease-relevant cell types for use in disease modeling and drug discovery.
Human synovial cells isolated from two 71-year-old women with advanced OA were characterized and reprogrammed into induced PSCs by ectopic expression of 4 transcription factors (Oct-4, SOX2, Klf4, and c-Myc). The pluripotency status of each induced PSC line was validated by comparison with human embryonic stem cells (ESCs).
We found that OA patient-derived human synovial cells had human mesenchymal stem cell (MSC)-like characteristics, as indicated by the expression of specific markers, including CD14-, CD19-, CD34-, CD45-, CD44+, CD51+, CD90+, CD105+, and CD147+. Microarray analysis of human MSCs and human synovial cells further determined their unique and overlapping gene expression patterns. The pluripotency of established human induced PSCs was confirmed by their human ESC-like morphology, expression of pluripotency markers, gene expression profiles, epigenetic status, normal karyotype, and in vitro and in vivo differentiation potential. The potential of human induced PSCs to differentiate into distinct mesenchymal cell lineages, such as osteoblasts, adipocytes, and chondrocytes, was further confirmed by positive expression of markers for respective cell types and positive staining with alizarin red S (osteoblasts), oil red O (adipocytes), or Alcian blue (chondrocytes). Functional chondrocyte differentiation of induced PSCs in pellet culture and 3-dimensional polycaprolactone scaffold culture was assessed by chondrocyte self-assembly and histology.
Our findings indicate that patient-derived synovial cells are an attractive source of MSCs as well as induced PSCs and have the potential to advance cartilage tissue engineering and cell-based models of cartilage defects.
Full-text · Article · Oct 2011 · Arthritis & Rheumatology
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study is to evaluate the change of mechanical properties and the effect of antibacterial reactions in calcium phosphate cement (CPC) mixed with cefazolin.
Preview · Article · Jan 2011 · The Journal of the Korean Orthopaedic Association
[Show abstract][Hide abstract] ABSTRACT: To elucidate the relation between fracture healing and angiogenesis, we checked expression of Hypoxia-inducible factor (HIF) and Vascular endothelial growth factor (VEGF) in hypoxic cell cultures and the callus from a rat femur fracture model.
Preview · Article · Jan 2008 · The Journal of the Korean Orthopaedic Association