ABSTRACT
Activin receptor-like kinase (ALK) 1 is a transforming growth factor-β/bone morphogenetic pro-teins superfamily type Ⅰ receptor, predominantly expressed in active endothelial cells. ALK1 has been shown to play a piv-otal role in regulating angiogenesis, which is involved in vascular formation during embryonic and early postnatal develop-ment and angiogenesis-related diseases, such as cardiovascular disorders and tumor. Understanding the exact function of ALK1 in angiogenesis will provide theoretical basis for anti-angiogenic strategy of ALK1 inhibition. In the present study, we briefly recapitulate ALK1 signaling pathway and its role in blood vessel formation and pathological neovascularization.
ABSTRACT
OBJECTIVE To determine the characterization, anti-tumor efficacy and pharmacokinetics of bufalin- loaded PEGylated liposomes compared with bufalin entity. METHODS Bufalin- loaded PEGylated liposomes and bufalin- loaded liposomes were prepared reproducibly with homogeneous particle size by the combination of thin film evaporation method and high pressure homogenization method. The particle size and zeta potential of the liposomes were determined by dynamic light scattering technique. The direct imaging of morphology of liposomes was charactered by transmission electron microscope. The content of bufalin in liposomes was analysed by HPLC method. The entrapment efficiency and the particle size was applied to assess the stability profile, after storage at 4℃ on day 0, 7, 15, 30 and 90. The in-vitro release behaviours of bufalin from liposomes were conducted using dialysis bag technique at 37℃. In-vitro cytotoxicity studies were carried out using MTT〔3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide〕assay on several kinds of tumor cell lines including SW620, PC-3, MDA-MB-231, A549, U251, U87 and HepG2. In-vivo pharmacokinetic study of bufalin liposomes was evaluated by HPLC method. RESULTS Their mean particle sizes were 127.6 nm and 155.0 nm, mean zeta potentials were 2.24 mV and - 18.5 mV, entrapment efficiencies were 76.31% and 78.40% , respectively. In- vitro release profile revealed that the release of bufalin in bufalin- loaded PEGylated liposomes was slower than that of bufalin-loaded liposomes. The cytotoxicity of blank liposomes has been found within acceptable range, whereas bufalin-loaded PEGylated liposomes showed enhanced cytotoxicity to U251 cells compared with bufalin entity. In-vivo pharmacokinetics indicated that bufalin-loaded PEGylated liposomes could extend eliminate half-life time of bufalin in plasma in rats. CONCLUSION The results suggested that bufalin-loaded PEGylated liposomes improved the solubility and increased the drug concentration in plasma.