Loading Psoralen into liposomes to enhance its stimulatory effect on the proliferation and differentiation of mouse calvarias osteoblasts

Psoralen (PSR), a well-known traditional Chinese medicine has been claimed for the treatment of osteoporosis. However, its hydrophobicity and the first-pass metabolism restrict the potential application of PSR. Thus, the development of PSR-loaded liposome was done to improve the solubility and bioavailability of PSR. The PSR/liposomes exhibited a particle size of approximately 110 nm and were quite stable during 30 days of storage. The entrapment efficiency (EE), drug loading (DL) and zeta potentials of PSR/liposome were 85.0 ± 1.6%, 5.0 ± 1.6% and -36 mV, respectively. Small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements suggested that PSR/liposomes are the mixture of unilamellar and multilamellar vesicles. The in vitro drug release profile of PSR/liposome exhibited a gradual behavior. Both pure PSR and PSR/liposome promoted osteoblast proliferation in a dose-dependent manner. The proliferation effect was firstly enhanced with drug concentration increased, and then decreased when the concentration was higher than 20 µM. But PSR/liposome could induce osteoblast proliferation in more gentle way through the sustained release of PSR. For the level of ALP activity, PSR/liposome was 1.2 times higher than pure PSR. Above all, it is expected that PSR/liposome could be used in osteoporosis treatment in the future.