Pentosan reduces osteonecrosis of femoral head in SHRSP

Increased oxidative stress is considered one of the main causes of steroid-induced osteonecrosis of the femoral head (ONFH). The aim of this study was to evaluate the effects of a steroid hormone and pentosan polysulfate sodium (pentosan), a heparin analog, in stroke-prone spontaneously hypertensive rats (SHRSP) as a model of ONFH. One hundred twenty-three 13-week-old male SHRSP/Izm rats were divided into four groups: a control group (group C), pentosan-administered group (group P), steroid-administered group (group S), and group administered pentosan plus steroid (group PS). Methylprednisolone acetate, as the steroid hormone, at a dose of 4 mg (15 mg/kg) was administered at 15 weeks of age. Pentosan at a dose of 3 mg/day/kg was continuously administered intraperitoneally from 13 weeks of age for 4 weeks. Rats were sacrificed at 17 weeks of age, and heart blood and both femora were collected. Triglyceride levels were significantly lower in group PS than in group S, indicating that pentosan improves lipid metabolism. The incidence of histologic ONFH was significantly lower in group P, at 14.8% (10/71 femoral heads), than in group C, at 30.4% (17/56 femoral heads), and significantly lower in group PS, at 40.8% (29/71 femoral heads), than in group S, at 91.3% (42/46 femoral heads), indicating that pentosan markedly inhibits ONFH. Immunohistochemical staining for oxidative stress showed that the stainability was significantly lower in group PS than in group S. Pentosan seems to reduce the incidence of ONFH in SHRSP by improving lipid metabolism and decreasing oxidative stress.