Efficacy of electrical polarization on a rat femoral bone defect model with a custom-made external fixator.

BACKGROUND: We have developed a technology to electrically polarize living bone. OBJECTIVE: The effects of stored electrical charge in electrical polarized bone on the facilitation of new bone formation were assayed. METHODS: Stimulated depolarized current measurement was performed in electrically polarized and nonpolarized femora of SD rats. These bone specimens were implanted into bone defects of the rat femora and fixed with a custom-made external fixator. X-ray imaging of the implant was performed every week. After 3 weeks, micro-CT scanning was performed to evaluate the displacement rate. Histological observation was performed, and the occupancy ratio of the newly formed bone was calculated from tissue specimens stained with Villanueva's Goldner method. RESULTS: There was a tendency for the displacement rate of the implant to be smaller and the occupancy ratio of the newly formed bone to be larger, especially at the distal end, in the polarized group compared with the nonpolarized group. The time of callus appearance was significantly earlier in the polarized group than in the nonpolarized group, and bridging callus grew from the distal to the proximal end. CONCLUSIONS: Bone specimens can be electrically polarized, and the stored electrical charge can work effectively to facilitate new bone formation.

Antitumor effects of pristimerin on human osteosarcoma cells in vitro and in vivo.

There are very few treatments for musculoskeletal tumors, compared to other cancers; thus, novel therapeutic drugs are needed. Pristimerin (PM) is a triterpene compound isolated from plant extracts that reportedly has antitumor effects on various cancers, such as of the breast and prostate. The purpose of this study was to evaluate the antitumor effects of PM on human osteosarcoma cells. Treatment of the human osteosarcoma cell lines, MNNG and 143B, with PM led to a dose-dependent decrease in cell viability. The effects of PM on apoptosis were evaluated with the Annexin V/propidium iodide assay and analysis of caspases 3, 8, and 9 activities. Western blot analysis showed that PM caused a decrease in the expression of Akt, mTOR, and NF-κB. The volumes and weights of human osteosarcoma xenografts decreased significantly with PM treatment. The results of this study revealed that PM can inhibit human osteosarcoma growth in vitro and in vivo, and may be a novel therapeutic agent for the disease.

Hepatocyte growth factor/c-met promotes proliferation, suppresses apoptosis, and improves matrix metabolism in rabbit nucleus pulposus cells in vitro.

The etiology of intervertebral disc (IVD) degeneration is closely related to apoptosis and extracellular matrix degradation in nucleus pulposus (NP) cells. These defects in NP cells are induced by excessive external stressors such as reactive oxygen species (ROS) and inflammatory cytokines. Recently, hepatocyte growth factor (HGF) has been shown to repair damage in various diseases through anti-apoptotic and anti-inflammatory activity. In this study, we investigated the effects of HGF on NP cell abnormality caused by ROS and inflammatory cytokines by using primary NP cells isolated from rabbit IVD. HGF significantly enhanced the proliferation of NP cells. Apoptosis of NP cells induced by H2 O2 or TNF-α was significantly inhibited by HGF. Induction of mRNA expression of the inflammation mediators cyclooxygenase-2 and matrix metalloproteinase-3 and -9 by TNF-α was significantly suppressed by HGF treatment. Expression of c-Met, a specific receptor for HGF, was confirmed in NP cells and was increased by TNF-α, suggesting that inflammatory cytokines increase sensitivity to HGF. These findings demonstrate that activation of HGF/c-Met signaling suppresses damage caused by ROS and inflammation in NP cells through multiple pathways. We further suggest the clinical potential of HGF for counteracting IVD degradation involved in NP cell abnormalities.

Femoral perfusion after pulsed electromagnetic field stimulation in a steroid-induced osteonecrosis model.

This study was designed to evaluate femoral perfusion after pulsed electromagnetic field (PEMF) stimulation in a steroid-induced osteonecrosis rabbit model by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Steroid-induced osteonecrosis was produced by single intramuscular injection of methylprednisolone in 15 rabbits. Eight rabbits underwent PEMF stimulation (PEMF group) and seven did not (control group). DCE-MRI was performed before PEMF stimulation, immediately before steroid administration, and 1, 5, 10, and 14 days after steroid administration. Regions of interest were set in the bilateral proximal femora. Enhancement ratio (ER), initial slope (IS), and area under the curve (AUC) were analyzed. ER, IS, and AUC in the control group significantly decreased after steroid administration compared with before administration (P<0.05). In PEMF group, IS significantly decreased; however, ER and AUC showed no significant differences after steroid administration compared with before. ER and IS in PEMF group were higher than in control group until 10th day, and AUC was higher until 5th day after steroid administration (P<0.05). PEMF stimulation restrains the decrease in blood flow after steroid administration.

Effect of light-emitting diode (LED) therapy on the development of osteoarthritis (OA) in a rabbit model.

OBJECTIVE: The objective of this study was to evaluate whether light-emitting diodes (LEDs) could be effective in a noninvasive, therapeutic device for the treatment of osteoarthritic (OA) knee joints. DESIGN: Five weeks following the anterior cruciate ligament transection (ACLT) of mature New Zealand White rabbits, the animal knees were exposed to LED stimulation at intervals of 10 min/day, 5 days/week for 5 weeks in the experimental group (n=7). The device used high intensity red and infrared (IR) LEDs with a total amount of energy delivered to the skin of 2.4 J/cm(2). Animals were sacrificed at 9 weeks postoperatively. Femoral surface gross morphology was evaluated with a modified Outerbridge classification and mRNA expression of catabolic and anabolic markers from femoral condyle cartilage and synovial tissue was assessed using RT-PCR. A control group was harvested 9 weeks following untreated ACLT. RESULTS: Gross morphometry of the control group showed four Grade II, two Grade III and one Grade IV (average 2.6) condyles macroscopically. The experimental group showed two Grade I and five Grade II (average 1.7) (Table 1). mRNA expression of aggrecan in the cartilage showed no difference between the groups, however type II collagen expression increased in the experimental group compared with control. TNF-α expression was significantly decreased in the experimental group compared to control. CONCLUSIONS: There was general preservation of the articular surface and decreased levels of inflammation in the osteoarthritic joints with the application of LED therapy. This may provide potential application as a noninvasive treatment.

Noninvasive up-regulation of angiopoietin-2 and fibroblast growth factor-2 in bone marrow by pulsed electromagnetic field therapy.

BACKGROUND: Pulsed electromagnetic field (PEMF) therapy has been widely used in clinical practice for bone fracture healing. However, the mechanism of its action remains to be elucidated. Our object was to investigate the mechanism by which PEMF accelerates bone fracture healing. METHODS: We used 20 mice in this study. Ten mice received PEMF for 10 h/day for 1 week via the coils of a PEMF stimulation device (PEMF group), while the remaining 10 mice did not (control group). The femurs were harvested immediately after euthanasia to examine the proteins included in the bone marrow. The proteins examined by Western blotting were growth factors with angiogenetic activities, including tunica interna endothelial cell kinase-2, angiopoietin-1, angiopoietin-2, fibroblast growth factor-2, and vascular endothelial growth factor. The expression levels of angiogenesis-related proteins extracted from the bone marrow of each mouse were compared. RESULTS: The expression levels of angiopoietin-2 and fibroblast growth factor-2 were significantly higher in the PEMF group than in the control group. This difference suggests that PEMF may induce an angiogenesis-prone environment in the bone marrow. Such angiogenesis acceleration represents one possible mechanism for the acceleration of bone fracture healing by PEMF. There were no significant differences between the two groups for the expression levels of tunica interna endothelial cell kinase-2, angiopoietin-1, and vascular endothelial growth factor. The lack of increase in tunica interna endothelial cell kinase-2 expression may indicate that PEMF does not unnecessarily increase blood vessels in normal bone marrow. The lack of an increase in the expression level of vascular endothelial growth factor suggests that PEMF does not have invasive effects including the induction of hypoxic conditions and inflammation on the bone marrow. CONCLUSION: The angiogenesis-promoting function of PEMF may contribute to its mechanism to noninvasively accelerate bone fracture healing.

A novel MEK1/2 inhibitor induces G1/S cell cycle arrest in human fibrosarcoma cells.

Blockade of the ERK pathway has antitumor effects against malignant tumor cells. In this study, we investigated the antitumor activity of JTP-70902, a novel specific MEK inhibitor, against human fibrosarcoma cells in which the ERK pathway is constitutively activated. JTP-70902 was synthesized at Japan Tabacco. Human fibrosarcoma HT1080 cells were cultured. JTP-70902 was added at various concentrations. The number of viable cells was counted employing a trypan blue dye exclusion test. Unsynchronized cells were exposed to JTP-70902 for 24 h. The nuclei were stained with propidium iodide. The DNA content was measured using a FACSCalibur flow cytometer. Protein extraction and Western blot analysis were performed. (1) A dose-dependent inhibition of cell growth was observed at concentrations of 10 nM or more. Forty-eight hours after the treatment, the growth of HT1080 cells was completely inhibited by 200 nM JTP-70902. (2) FACS analysis revealed that a 24-h exposure to JTP-70902 increased the population of G1/S phase cells in a dose-dependent manner. (3) The phosphorylation of ERK was inhibited by JTP-70902. Furthermore, after the treatment with JTP-70902, p21WAF1/CIP1 and p27KIP1 protein expression increased and the phosphorylation of RB was reduced. Our results showed that JTP-70902 inhibits cell growth and induces cell cycle arrest in human Ras mutant fibrosarcoma cells. These results indicate that JTP-70902 might be an attractive compound for molecular-targeting chemotherapy for malignant soft tissue tumors with the activation of the Ras-MEK-ERK pathway.

Zoledronic acid inhibits proliferation of human fibrosarcoma cells with induction of apoptosis, and shows combined effects with other anticancer agents.

Third-generation bisphosphonates are known to inhibit bone resorption and also appear to exhibit direct anti-tumour activity. We previously reported that third-generation bisphosphonates such as zoledronic acid (ZOL) have a direct antitumour effect, and synergistically augment the effects of antitumor agents in osteosarcoma cells. There has been no report on the antitumor effect of ZOL against soft tissue sarcoma. The aim of this study was to evaluate the antitumor effect of this drug on a human fibrosarcoma cell line, in terms of proliferation and apoptosis, and, moreover, to evaluate the combined effects of ZOL with other antitumor drugs against the human fibrosarcoma cell line. HT1080 cells were treated with ZOL at various concentrations up to 10 microM, and then cell proliferation, cell cycle, nuclear morphology, and Western blot analyses were performed to study the antitumor effects of ZOL alone, and, moreover, HT1080 cells were treated with ZOL and other anticancer drugs such as paclitaxel, docetaxel, doxorubicin, etoposide, 5-fluorouracil, gemcitabine, cisplatin, or methotrexate to investigate the combined effects using proliferation and cell cycle analyses. We found that ZOL strongly inhibited in vitro proliferation, arrested the cell cycle between S and G2/M phases, and induced the apoptosis of human fibrosarcoma cells. Moreover, ZOL augmented the effect of antitumor agents when administered concurrently with paclitaxel, docetaxel, doxorubicin, etoposide, 5-fluorouracil, gemcitabine, and cisplatin in human fibrosarcoma cells. The treatment of fibrosarcoma with ordinary antitumor drugs is not fully effective. These findings suggest that ZOL directly affects the proliferation and survival of fibrosarcoma cells, and that the combined administration of ZOL with other antitumor agents may improve the efficacy of fibrosarcoma treatment. These results support the possibility that their combined use could be beneficial in the treatment of patients not only with various types of cancer or osteosarcoma, but also with soft tissue sarcoma.

Vitamin E prevents steroid-induced osteonecrosis in rabbits.

BACKGROUND AND PURPOSE: Prevention of osteonecrosis after corticosteroid administration would be important. We examined the potential of vitamin E (alpha-tocopherol) to reduce the incidence of corticosteroid-induced osteonecrosis in an animal model. METHODS: Japanese white rabbits were divided into 2 groups; the control group was fed a normal diet and the experimental group was fed alpha-tocopherol-supplemented diet in which alpha-tocopherol (600 mg/kg diet) was added to the normal diet. To induce osteonecrosis, high-dose methylprednisolone acetate (MPSL) (20 mg/kg body weight) was injected once into the right gluteus medius muscle of all rabbits. 4 weeks after the injection of MPSL, the presence or absence of osteonecrosis of bilateral femurs was examined histopathologically. The tocopherol/cholesterol ratios were calculated. The plasma levels of thiobarbituric acid-reactive substances (TBARS) were measured. RESULTS: Alpha-tocopherol-supplemented diet reduced the incidence of osteonecrosis, which developed in 14 of 20 rabbits in the control group and 5 of 21 rabbits in the experimental group (p = 0.004). The tocopherol/cholesterol ratio was higher in the experimental group than in the control group after the alpha-tocopherol administration. The plasma TBARS level was lower in the experimental group than in the control group at 4 weeks after the MPSL administration. INTERPRETATION: Our findings may offer a new approach for the prevention of corticosteroid-induced osteonecrosis.

MDR1a/1b gene silencing enhances drug sensitivity in rat fibroblast-like synoviocytes.

BACKGROUND: Drug resistance mediated by P-glycoprotein (P-gp) is one of the major reasons for the failure of rheumatoid arthritis (RA) therapy with disease modifying anti-rheumatic drugs and glucocorticoids. In the present study, we aimed to investigate the in vitro effectiveness of small interfering RNA (siRNA) to render rat fibroblast-like synoviocytes (FLS) susceptible to drugs. We also attempted the electroporation-mediated transfer of siRNA against multidrug resistance (MDR) genes into rat knee joints. METHODS: FLS were transfected with siRNAs corresponding to MDR1a and MDR1b genes. FLS were treated with dexamethasone (DEX) and lipopolysaccharide. The mRNA and protein levels of tumor necrosis factor-alpha, interleukin (IL)-6 and IL-1beta were measured. Both siRNAs were co-transduced into rat knee joints by an electroporation method and evaluated the target gene expressions in the synovium. RESULTS: Each siRNA could sequence-specifically reduce the target gene expression by over 70% and effectively suppressed P-gp expression and function in the FLS. Both gene expression and protein production of the inflammatory cytokines in the cells transfected with siRNA were reduced by a greater amount compared to in control cells. The in vivo electroporation-mediated transduction of siRNA could significantly inhibit the target gene expressions. CONCLUSIONS: MDR1a/1b gene silencing by siRNA could effectively inhibit P-gp in rat FLS, resulting in a significant enhancement of the anti-inflammatory effects of DEX. The in vivo siRNA transduction could successfully silence MDR gene expression in the rat synovium. These findings indicate that the siRNA targeting MDR gene could be a useful tool for treating refractory arthritis in RA.

Hyperthermia for the treatment of articular cartilage with osteoarthritis.

Osteoarthritis (OA) is one of the most frequent musculoskeletal disorders in the elderly population. OA is characterised by a gradual loss of extracellular matrix in the articular cartilage of joints. OA can only be managed by artificial joint replacement when joint destruction becomes severe. Therefore, it is preferable to administer conservative therapy that is easy, simple and effective in inhibiting OA progression at the early stage. Heat shock protein 70 (Hsp70) has a protective effect on the cartilage and inhibits the apoptosis of chondrocytes. Heat stimulation by microwave to the joints can increase Hsp70 expression in chondrocytes, and at the same time, Hsp70 expression partially enhances matrix metabolism of the cartilage. These findings suggest that hyperthermia can be positively applied to the treatment of OA. Hyperthermia is therefore expected to be an inexpensive and less-invasive conservative therapy for OA.

[Bone fracture and the healing mechanisms. Fracture treatment using electrical stimulation].

In 1953, Iwao Yasuda reported on the piezoelectricity of bone and the electrical stimulation of callus formation. Subsequently, various methods of electrical stimulation have been investigated, and the enhancement of callus formation by electrical stimulation is likely to have broad clinical applications for not only the repair of fractures, but also for nonunion and pseudoarthrosis. Recently, these outcomes have been validated by significant double blind clinical trials, and the electrical currents in bone were investigated at the molecular level. Moreover, the application of impedance measurements obtained upon electrical stimulation as a means to evaluate bone maturation was examined. This paper reports on the current methods of electrical stimulation, the fundamental effects on bone formation, and further clinical applications.

Low-energy laser irradiation promotes synovial fibroblast proliferation by modulating p15 subcellular localization.

BACKGROUND AND OBJECTIVE: Low-energy laser irradiation (low-level laser therapy) (LELI/LLLT/photobiomodulation) has been found to modulate various biological effects, especially those involved in promoting cell proliferation. Synovial fibroblasts are important in maintaining the homeostasis of articular joints and have strong chondrogenetic capacity. Here, we investigated the effect and molecular basis of LELI on synovial fibroblast proliferation. STUDY DESIGN/MATERIALS AND METHODS: HIG-82 rabbit synovial fibroblasts were cultured, and laser irradiation (660 nm) was applied at the power density of 40 mW/cm(2) for 2 minutes, corresponding to laser fluence of 4.8 J/cm(2). The effect of LELI on cell proliferation, cell cycle progression, and expression of cyclin-dependent kinase inhibitors (CKIs) were investigated. We also examined whether the effects of LELI on HIG-82 cell proliferation were affected by cAMP content, which is known to influence the cell cycle via inducing CKIs. RESULTS: LELI promoted HIG-82 synovial fibroblast proliferation and induced cytoplasmic localization of cyclin-dependent kinase inhibitor p15 (INK4B/CDKN2B). Moreover, the proliferation of HIG-82 synovial fibroblasts was reduced by cAMP, while cAMP inhibitor, SQ22536, induced p15 cytoplasmic localization and as a result, elevated synovial fibroblast proliferation was observed. In addition, the promotive effect of LELI-induced HIG-82 synovial fibroblast proliferation was abolished by cAMP treatment. Our findings suggest that cAMP may be involved in the effect of LELI on synovial fibroblast proliferation. CONCLUSION: We revealed the effect and molecular link involved in synovial fibroblast proliferation induced by 660-nm LELI. Our study provides new insights into the mechanisms by which LELI has biological effects on synovial fibroblast proliferation. These insights may contribute to further investigation on biological effects and application of LELI in regenerative medicine.

Electromagnetic fields: a novel prophylaxis for steroid-induced osteonecrosis.

Establishing a means to prevent osteonecrosis after corticosteroid administration is an important theme. We asked whether pulsed electromagnetic field stimulation, a noninvasive treatment, could prevent osteonecrosis. Ninety rabbits were divided into four treatment groups: (1) exposure of 10 hours per day to electromagnetic stimulation for 1 week, followed by injection of methylprednisolone (20 mg/kg), and exposure of 10 hours per day to electromagnetism for a further 4 weeks (n = 40); (2) methylprednisolone injection only (n = 40); (3) no treatment (n = 5); and (4) exposure of 10 hours per day to electromagnetism for 5 weeks (n = 5). After 5 weeks, we harvested and histologically examined femurs bilaterally. The frequency of osteonecrosis was lower in the steroid-electromagnetism group (15/40) than in the steroid-only group (26/40). No necrotic lesions were found in the two control groups. We observed no clear effects of electromagnetism on the number, location, extent, and repair of necrotic lesions and intramedullary fat cell size in affected rabbits. Pulsed electromagnetic field stimulation reportedly augments angiogenesis factors and dilates blood vessels; these effects may lower the frequency of osteonecrosis. Exposure to pulsed electromagnetic field stimulation before corticosteroid administration could be an effective means to reduce the risk of osteonecrosis.

The plant alkaloid cryptolepine induces p21WAF1/CIP1 and cell cycle arrest in a human osteosarcoma cell line.

We previously established a bioassay method to screen for compounds that activate the promoter activity of p21(WAF1/CIP1), a potent inhibitor of cyclin-dependent kinases, in a p53-independent manner. As an activator of p21(WAF1/CIP1) promoter activity, we isolated cryptolepine (CLP: 5-methyl indolo (2,3b)-quiniine), an indoloquinoline alkaloid, from the traditional Ayurvedic medicinal plant Sida cordifolia. We show here that CLP induces the expression of p21(WAF1/CIP1) with growth arrest in p53-mutated human osteosarcoma MG63 cells. Four micromolar of CLP completely inhibited the growth of MG63 cells and caused G2/M-phase arrest. CLP up-regulated the expression of p21(WAF1/CIP1) at both mRNA and protein levels in a dose-dependent manner. Using several mutant p21(WAF1/CIP1) promoter constructs, we found that the CLP-responsive element is an Sp1 site at -82 relative to the transcription start site of the p21(WAF1/CIP1) promoter. These findings suggest that CLP arrests the growth of MG63 cells by activating the p21(WAF1/CIP1) promoter through the specific Sp1 site in a p53-independent manner. In addition, CLP-mediated cell cycle arrest was reduced by the knockout of the p21(WAF1/CIP1) gene in human colon cancer HCT116 cells, suggesting that the cell cycle arrest by CLP was at least partially mediated through the induction of p21(WAF1/CIP1) expression. Although we need further study of chemotherapeutic effect in vivo, these results raise the possibility that CLP might be a suitable chemotherapeutic agent for treatment of osteosarcoma.

The effect of apoptosis signal-regulating kinase 1 gene transfer on rat collagen induced arthritis.

OBJECTIVE: To examine the apoptosis-inducing effect of apoptosis signal-regulating kinase 1 (ASK1) gene transfer into synovial cells in vitro and in vivo. METHODS: An adenovirus vector was constructed so that a constitutively active form of ASK1 gene (ASK1DeltaN) was expressed in the presence of the Cre recombinase. The ASK1DeltaN and Cre adenovirus vectors were cotransduced into cultured synoviocytes derived from patients with rheumatoid arthritis (RA), and apoptosis was evaluated by TUNEL and Hoechst staining. Collagen induced arthritis (CIA) was induced in 8-week-old male DA rats, and 10 days later the 2 adenovirus vectors were coadministered into the ankle joints of the animals. As indicators of severity of arthritis, swelling of the ankle and articular index (AI) scores were evaluated, while histopathological observation of articular tissue was also performed. RESULTS: In the cultured human RA synoviocytes, overexpression of the ASK1DeltaN significantly reduced cell viability and induced apoptosis. In the CIA rats transduced with the ASK1DeltaN gene, arthritis was significantly promoted in terms of the swelling of the ankle joints and elevation of the AI scores. Histopathological observation also revealed that the constitutively active ASK1 induced massive infiltration of inflammatory cells into the synovial membrane as well as proliferation of synovial fibroblasts. Degeneration of the synovial membrane was not evident. CONCLUSION: Adenoviral transduction of ASK1DeltaN induced apoptosis in RA synoviocytes in vitro, but not in CIA synovium in vivo.

Effect of heat stimulation on viability and proteoglycan metabolism of cultured chondrocytes: preliminary report.

Thermotherapy has been applied to various joint diseases and injuries, but its direct effects on articular cartilage have remained unclear. The present study examined the effects on cell viability and metabolism by using the chondrocyte-like cell line HCS-2/8. The temperatures and durations of heat stimulation were 39 degrees, 41 degrees, 43 degrees, and 45 degrees C for 15 or 30 min. After heat stimulation of 41 degrees C or lower for 15 or 30 min, cell viability increased and proteoglycan metabolism was accelerated, whereas after stimulation at 43 degrees C or higher for 30 min the viability and metabolism decreased. These results indicate that appropriate heat stimulation positively affects cell viability and the proteoglycan metabolism of articular cartilage, whereas too much heat stimulation produces negative effects. Clinical efficacy is therefore determined by the overall thermal dose. When the appropriate combination of temperature and duration is found, thermotherapy for diseases and injury of articular cartilage can be highly useful in clinical practice.