[Effects of HS 6101 and rhG-CSF on Hematopoiesis Recovery of ICR Mice Injured by Cyclophosphamide].

OBJECTIVE: To investigate the effects of HS 6101 and recombinant human granulocyte colony stimulating factor (rhG-CSF) on hematopoiesis recovery of ICR mice injured by cyclophosphamide (CTX). METHODS: A total of 103 ICR mice were divided into 4 groups, including CTX control (46 mice), HS 6101 (21 mice), rhG-CSF (18 mice) and HS 6101+rhG-CSF (18 mice), respectively. The mouse model of chemotherapy-induced haematopoietic injury was established by CTX intraperitoneal injection at a dose of 100 mg/kg once a day for 3 consecutive days. Single dose of HS 6101 (27 µg/mouse) was injected subcutaneously at 1 hour before the first administration of CTX. One day after the last CTX treatment, 2 µg/mouse of rhG-CSF was injected subcutaneously once a day for 5 consecutive days. The peripheral blood cell counts of the mice were observed once every 2 days. Hematopoietic progenitor cell colony counting and histopathological assessment of bone marrow cells were evaluated in the mice at days 4 and 9 after the first administration of CTX. RESULTS: Both HS 6101 and rhG-CSF alone or in combination, significantly elevated the nadirs of peripheral blood leukocytes and neutrophils, increased the number of bone marrow hematopoietic progenitor cells, and stimulated the hematopoietic cell hyperplasia of bone marrow in the mice treated with CTX. The effect of HS 6101 combined with rhG-CSF was better than that of the drugs used alone. CONCLUSION: The HS 6101 at 27 µg/mouse can significantly promote the recovery of hematopoiesis in ICR mice treated with CTX chemotherapy, and its combination with rhG-CSF shows synergistic effects.

[Protective effect of HS-6101 on rhesus monkeys with severe hematopoietic acute radiation sickness].

This study was purposed to investigate the protective effects of lipoprotein HS-6101(6101) on rhesus monkey total body irradiated with 7.0 Gy 6°Coγ-ray. A total of 30 health adult rhesus monkeys were randomly divided into symptomatic therapy (ST), WR2721 and HS-6101 30, 90 and 270 mg/kg groups (n = 6), the rhesus monkeys of each groups were injected with physiological saline 0.3 ml/kg, WR-2721 30 mg/kg, or HS-6101 30, 90 and 270 µg/kg, respectively. All agents were once intramuscularly injected at 1 hr prior irradiation. General observation, peripheral blood cell counts, colony forming unite assay of bone marrow hemopoietic progenitor cells, and histopathological examination were performed. The results showed that animals in symptomatic therapy group begin to die on the 13(th) day and 4 animals died within 24 days, the average survival time was 18.2 ± 4.3 days; 2 animals in WR-2717 groups died on day 15.8 and day 18.5 post irradiation respectively. 1 animal in HS-6101 270 mg/kg group died on day 35.8, all other animals survived. Nadirs of peripheral blood white blood cells, neutrophils and platelets of animals in HS-6101 treatment groups were significantly higher than those in other 2 groups including ST and WR-2721 groups, and the hemopoietic recovery were also significantly speeding up(P < 0.05 and 0.01). In vitro results showed that HS-6101 obviously promoted 7.0 Gy 6°Coγ irradiated monkey's bone marrow mononuclear cells to form various hematopoietic progenitor cell colonies (P < 0.05 and 0.01) . Compared with symptomatic therapy and WR-2717 groups, bone marrow histopathological changes in HS-6101 treatment groups showed more active hemopoietic cell proliferation and higher density structure. It is concluded that HS-6101 90 µg/kg treatment can promote the bone marrow recovery of 7.0 Gy 6°Coγ irradiated monkey, alleviate their animal symptom, simplify the treatment measures and improve the animal survival rate. The HS-6101 shows remarkable radioprotective effects as compared with the currently internationally acknowledged radioprotectant of WR-2721.

Determination of HS270, a new histone deacetylase inhibitor, in rat plasma by LC-MS/MS--application to a preclinical pharmacokinetic study.

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) method has been developed and fully validated to determine HS270, a new histone deacetylase (HDAC) inhibitor, in rat plasma using SAHA as the internal standard (IS). After a single step liquid-liquid extraction with acetoacetate, analytes were subjected to LC-MS/MS analysis using positive electro-spray ionization (ESI(+)) under selected reaction monitoring mode (SRM). The chromatographic separation was achieved on a Hypurity C(18) column (50 mm × 2.1 mm, i.d., 5 µm). The MS/MS detection was conducted by monitoring the fragmentation of m/z 392.3→100.1 for HS270, m/z 265.1→232.1 for IS. The method had a chromatographic running time of 2.5 min and linear calibration curves over the concentrations of 0.5-1000 ng/mL. The recovery of the method was 70.8-82.5% and the lower limit of quantification (LLOQ) was 0.5 ng/mL. The intra- and inter-batch precisions were less than 15% for all quality control samples at concentrations of 1.0, 100.0, and 750.0 ng/mL. The validated LC-MS/MS method has successfully applied to a HS270 pharmacokinetic study after oral doses of 25, 50, 100, 200 mg/kg, and i.v. dose of 5 mg/kg to rats.