Comparative Evaluation of Fibrin for Bone Regeneration in Critical Size Calvarial Defects

Natural biopolymers such as collagen and fibrin have been widely used in bone regenerative applications. Despite the frequent use, their comparative biological propertiesis are largely unknown. In a previous study, we found the superiority of fibrin to collagen in the adsorption of serum proteins and the proliferation and differentiation of cultured osteoblasts. In this study, we used an in vivo model to evaluate how effectively fibrin supports bone regeneration, as compared with collagen. Collagen and fibrin were placed in critical size defects made on rat calvarial bones. Compared with collagen, fibrin supported substantially more new bone tissue formation, which was confirmed by micro-CT measurement and histological analyses. The cells in the regenerative tissues of the fibrin-filled defects were immunostained strongly for Runx2, while collagen-placed defects were stained weakly. These in vivo results demonstrate that fibrin is superior to collagen in supporting bone regeneration.

Osteoblast differentiation of human bone marrow stromal cells (hBMSC) according to age for bone tissue engineering

Tissue engineered bone (TEB) can replace an autogenous bone graft requiring an secondary operation site as well as avoid complications like inflammation or infection from xenogenic or synthetic bone graft. Adult mesenchymal stem cells (MSC) for TEB are considered to have various ranges of differentiation capacity or multipotency by the donor site and age. This study examined the effect of age on proliferation capacity, differentiation capacity and bone morphogenetic protein-2 (BMP-2) responsiveness of human bone marrow stromal cells (hBMSC) according to the age. In addition, to evaluate the effect on enhancement for osteoblast differentiation, the hBMSC were treated with Trichostatin A (TSA) and 5-Azacitidine (5-AZC) which was HDAC inhibitors and methyltransferase inhibitors respectively affecting chromatin remodeling temporarily and reversibly. The young and old group of hBMSC obtained from the iliac crest from total 9 healthy patients, showed similar proliferation capacity. Cell surface markers such as CD34, CD45, CD90 and CD105 showed uniform expression regardless of age. However, the young group showed more prominent transdifferentiation capacity with adipogenic differentiation. The osteoblast differentiation capacity or BMP responsiveness was low and similar between young and old group. TSA and 5-AZC showed potential for enhancing the BMP effect on osteoblast differentiation by increasing the expression level of osteogenic master gene, such as DLX5, ALP. More study will be needed to determine the positive effect of the reversible function of HDAC inhibitors or methyltransferase inhibitors on enhancing the low osteoblast differentiation capacity of hBMSC.

Gorham-Stout Disease of the Mandible: A Case Report

The study on the development of relative value in medical treatment of the oral and maxillofacial surgery

The aim of this study is to evaluate the reasonableness of the medical fee on oral and maxillofacial surgery field according to surgeon's opinions and actual conditions. The medical fee has significant influence on hospital income, the supply and distribution of medical manpower, quality and facilities of medical services. Questionnaire survey was sent to 86 oral and maxillofacial surgeons who worked more than 3 years in general hospital. Among them, 25 doctors replied the 109 answers survey and the average of treatment time and physician work relative value on each category was calculated. And the health insurance cost (that has been applied since 2003) was compared with the questionnaire results. And finally we investigated items that health insurance system did not include in oral and maxillofacial field but actually performed in oral and maxillofacial surgery clinic. The result was that the medical fee did not properly reflect physician work relative value of actual treatments. In case of complicated extraction, work relative value needed 3.5 times enhancement of present value. For simple impacted tooth extraction 1.8 times, for impacted tooth extraction including odontomy 1.7 times, and for fully impacted tooth more than 2/3 of it located into the alveolar bone, 1.8 times enhancement needed. In respect of the present physician work relative value, hemimandibulectomy with neck lymph node dissection for the malignancy is appropriated as 3.3 times of open reduction and internal fixation for the mandibular fracture, but the questionnaire result showed 25 times discrepancy. In conclusion, this research shows the need for intervention that health insurance included items and legal relative medical value must act in union with treatment in clinic to reduce the imbalance between them.

Effects of bFGF and PDGF-BB on osteoblast differentiation of bone marrow-derived mesenchymal stem cell in rat

In this study we evaluate the effects of bFGF-BB and PDGF on in vitro proliferation, differentiation and mineralization of mesenchymal stem cells (MSCs) from rat. MSCs were prepared from the bone marrow of 6 or 7-week-old male rats with a technique previously described by Maniatopoulos et al. in 1988. Lineage differentiation to osteogenesis, chondrogenesis and adipogenesis were performed. At first, we characterized the cultured cell on passage 1, 3, 5, 7 with immunocytochemical staining using CD29, 44, 34, 45, alpha-SMA and type I collagen. And to study the effects of bFGF and PDGF-BB on proliferation, differentiation and mineralization, we seeded the expanded cell at a density of 6 x 10(3) cells/cm2 to 100-mm dish for evaluation of cell proliferation and MTT assay was carried out on day 2, 4, 7, 9. We also resuspended the cells with same density (6 x 10(3) cells/cm2) to 24 well plates for subculture. On the following day, the attached cells were exposed to 2.5ng/ml bFGF and/or 25ng/ml PDGF-BB daily during 5 days. The osteocalcin (OC) level was assessed and mineral contents were evaluated with alizarin red S staining on subculture day 2, 7, 14, 21. We identified the mesenchymal stem cell from the bone marrow derived cells of rat through their successful multi-differentiation and stable display of its phenotype. And bFGF and PDGF-BB showed the effect that inhibited osteoblastic differentiation and mineralization mildly in above concentration at in vitro culture.