Interaction of liposomal incorporated vitamin D3-analogues and human keratinocytes.

The influence of different liposomal qualities, loaded with a variety of vitamin D3-analogues, on the proliferation and interleucine 1 alpha-release (IL-1 alpha) of human keratinocytes was examined by fluorimetric and colorimetric measurements to optimize their use for psoriasis treatment. In comparison, the effects of the free drugs, as 25-hydroxyvitamin D3, calcipotriol, and calcitriol, as well as of empty liposomes have been studied. At the interaction between empty liposomes (< 200 nm) and HaCaT-cells has been looked by electron microscopy. Empty liposomes, made of DMPC as well as of egg-PC, can be used as drug carrier without any inhibiting effect on the proliferation of human keratinocytes at lipid concentrations of < 10(-4) M. Under the influence of the free drugs investigated an inhibition of cell growth as well as of the IL 1 alpha-release was measured at drug concentrations of > or = 10(-8) M. In comparison the related liposomal drug formulations didn't show any diminishing in the proliferation effects caused by the free drugs. A significant improvement, however, was only found in the action of DMPC-incorporated 25-hydroxyvitamin D3 at drug concentration of 10(-7) M. These results suggest that there is no remarkable improvement in the action of liposomal incorporated vitamin D3-analogues neither related to their proliferation nor their IL1 alpha-releasing effects. The influence of liposomal incorporated vitamin D3-analogues in keeping small their negative side effects has to be investigated at a more relevant model.