The effects of a single intravenous injection of novel activin A/BMP-2 (AB204) on toxicity and the respiratory and central nervous systems.

The purpose of this study was to determine the effects of a single intravenous injection of a novel osteoinductive material, activin A/BMP-2 (AB204), to rodents on toxicity and their respiratory functions and central nervous system (CNS). A single intravenous injection of AB204 was given to Sprague-Dawley (SD) rats in doses of 0, 0.625, 2.5 and 10 mg/kg to observe the mortality rate, the general symptoms for 14 days. The experimental groups were also given 0.2, 0.4 and 0.8 mg/kg of AB204, respectively, and the respiration rate, the tidal volume and the minute volume were measured for 240 min. The experimental groups of imprinting control region (ICR) mice were given a single intravenous injection of 0.2, 0.4 and 0.8 mg/kg of AB204, respectively. Their body temperature was taken and general behaviors were observed to evaluate the effect of AB204 on the CNS for 240 min. The study on toxicity of a single intravenous injection found no death or abnormal symptoms, abnormal findings from autopsy, or abnormal body weight gain or loss in all the experimental groups. No abnormal variation associated with the test substance was observed in the respiration rate, the tidal volume, the minute volume, body temperature or the general behaviors. On the basis of these results, the approximate lethal dose of AB204 for a single intravenous injection exceeds 10 mg/kg for SD rats and a single intravenous injection of ≤0.8 mg/kg AB204 has no effect on their respiratory system for SD rat and no effect on their CNS for ICR mice.

Characterization of Activin/BMP2 chimera, AB204, formulated for preclinical studies.

AB204 is an Activin/BMP2 chimera, which has been found to exhibit a higher activity than Bone Morphogenetic Protein 2 (BMP2) in osteogenic activity. To prepare AB204 for its preclinical studies, AB204 has been characterized in various formulation buffers. We observed that AB204 purified by ion-exchange chromatography has low water solubility (2.0 mg/ml), whereas it has high water solubility (higher than 10.0 mg/ml) when purified by reverse-phase chromatography. Analysis of the purification procedures reveals that the buffer composition at the lyophilization step determines the solubility. Lyophilization from sodium acetate buffer at pH 4.5 resulted in formation of sodium hydroxide, which caused low solubility of AB204 by pH increase upon reconstitution in water. However, lyophilization from buffers, containing acetic acid or trifluoroacetic acid (TFA) rendered AB204 to be highly soluble. During the course of these analyses, we found a simple procedure to further reduce residual amount of TFA in the purified AB204.