Therapeutic effects of intra-articular ultra-purified low endotoxin alginate administration on an experimental canine osteoarthritis model.

OBJECTIVE: This study aimed to elucidate the therapeutic effects of intra-articular administration of ultra-purified low endotoxin alginate (UPLE-alginate) on osteoarthritis (OA) using a canine anterior cruciate ligament transection (ACLT) model. DESIGN: We used 20 beagle dogs. ACLT was performed on the left knee of each dog and a sham operation was performed on the right knee as a control. All animals were randomly divided into the control (saline) and therapeutic (UPLE-alginate) groups. Animals in the control and therapeutic groups received weekly injections with 0.7 mL normal saline or 0.7 mL 0.5% UPLE-alginate, respectively, from 0 to 3 weeks after ACLT or sham operation. At 9 weeks after ACLT, the knee joints of all animals were observed using arthroscopy. All animals were euthanized at 14 weeks after ACLT and evaluated using morphologic assessment, histologic assessment, and biomechanical testing. RESULTS: Arthroscopic findings showed intact cartilage surface in both groups. Morphologic findings in the therapeutic group showed milder degeneration compared with those of the control group, but there were no significant differences between groups. Histologic scores of the medial femoral condyle (MFC) and lateral femoral condyle (LFC) were better in the therapeutic group than the control group (MFC: p = 0.009, LFC: p = 0.009). Joint lubrication did not differ significantly between groups. CONCLUSION: Intra-articular administration of UPLE-alginate in the early stage of OA slowed disease progression in canines. UPLE-alginate may have potential as a therapeutic agent for OA patients and reduce the number of patients who need to undergo total joint arthroplasty.

Studies on the metabolic fate of M17055, a novel diuretic (4): species difference in metabolic pathway and identification of human CYP isoform responsible for the metabolism of M17055.

The metabolic profile of M17055, a novel diuretic, after administration to experimental animals and after incubation with human liver microsomes was investigated. 1. Extensive metabolism was observed in rats and monkeys and the structures of six metabolites (RU1, RU2, and RU3 from rat urine or liver perfusate; MU1, MU2 and MU3 from monkey urine) were assumed or identified. The clear species difference of metabolism was revealed between rats and a monkey with different structures of the isolated metabolites. 2. When these metabolites were quantified using radioactive material, RU3, RU1 and MU3 were considered to be major metabolites in rat urine, rat bile and monkey urine respectively, while in a dog, unchanged drug was observed as the major component indicating only little metabolism occurred in dog, when administered intravenously. 3. RU1 and RU2 were also generated from [(14)C]M17055 after incubation with human liver microsomes, suggesting that the metabolic pathway of M17055 in humans involves that observed in rats. 4. [(14)C]M17055 metabolism in human liver microsomes was inhibited by CYP2C8/9 and CYP3A4/5 inhibitors, and also by the antibodies that recognize CYP2C8/9/19 and CYP3A4. Significant correlations were observed between the rate of [(14)C]M17055 metabolism and the activity of testosterone 6beta-hydroxylation or tolbutamide methyl-hydroxylation. cDNA-expressed CYP3A4 and CYP2C9 could catalyze the metabolism of [(14)C]M17055. These results suggest that the metabolism of M17055 in human liver microsomes is catalyzed mainly by CYP3A4 and CYP2C9.

Studies on the metabolic fate of m17055, a novel diuretic (5): pharmacokinetics and pharmacodynamics of unchanged drug in rat and dog after intravenous administration of M17055.

The pharmacokinetics and pharamacodynamics of M17055, a novel diuretic were studied after a single intravenous administration to rats and dogs, the two species used in the pharmacological and toxicological studies. No gender dependent response to systemic exposure was observed at the high dose level in rats, in agreement with the determined LD(50). A gender difference in urinary excretion of M17055, however, was clearly observed in rats. The slower elimination and the lower total body clearance (CLtot) values of M17055 in dogs reflect the difference of the no-effect level (NOEL) between rats (0.1 mg/kg) and dogs (0.03 mg/kg) well. The diuretic response was well correlated with the urinary M17055 excretion rate by fitting to a sigmoid E(max) model in both rats and dogs. The derived ER(50) value of M17055 in dogs was approximately 10 times less than that reported for furosemide, suggesting that the intrinsic potency of M17055 is equal to or higher than those of other powerful loop diuretics. Although diuretic sensitivity was considered to be lower in dogs than in rats, the higher amount of M17055 reaching the dog kidney is likely to compensate for this. The diuretic response in female rats was predictable by using the pharmacodynamic parameters derived from male rats. These results show that the apparent high diuretic potency and the other pivotal observations for M17055 found in the pharmacological and toxicological studies can be rationalized by the pharmacokinetic and pharmacodynamic properties of the unchanged compound.

Repair of articular cartilage defects with a novel injectable in situ forming material in a canine model.

We developed an ultra-purified in situ forming gel as an injectable delivery vehicle of bone marrow stromal cells (BMSCs). Our objective was to assess reparative tissues treated with autologous BMSCs implanted using the injectable implantation system into osteochondral defects in a canine model. Forty-eight osteochondral defects in the patella groove of the knee joint were created in 12 adult beagle dogs (two defects in each knee). The defects were divided into a defect group (n = 16), an acellular novel material implantation (material) group (n = 16), and a BMSCs implantation using the current vehicle system (material with BMSCs) group (n = 16). The reparative tissues at 16 weeks postoperatively were assessed through gross, histological, and mechanical analyses. The reparative tissues of the material with BMSCs group were substituted with firm and smooth hyaline-like cartilage tissue that was perfectly integrated into the host tissues. This treatment group obviously enhanced the subchondral bone reconstruction. The compressive modulus of the reparative tissues was significantly higher in the material with BMSCs group than the other groups. This study demonstrated that the implantation of BMSCs using our novel in situ forming material induced a mature hyaline-like cartilage repair of osteochondral defects in a canine model.