In liposomal delivery, a big question is how to release the loaded material into the correct place. Here, we will test the targeting and release abilities of our
sphingomyelin-consisting
liposome. A change in release parameters can be observed when
sphingomyelin-containing
liposome is treated with
sphingomyelinase enzyme.
Sphingomyelinase is known to be endogenously released from the different cells in stress situations. We assume the effective
enzyme treatment will weaken the
liposome making it also leakier. To test the release abilities of the SM-
liposome, we developed several fluorescence-based experiments. In in vitro studies, we used molecular quenching to study the
sphingomyelinase enzyme-based release from the
liposomes. We could show that the
enzyme treatment releases loaded fluorescent markers from
sphingomyelin-containing
liposomes. Moreover, the release correlated with used enzymatic activities. We studied whether the stress-related
enzyme expression is increased if the cells are treated with radiation as a stress inducer. It appeared that the radiation caused increased enzymatic activity. We studied our
liposomes' biodistribution in the animal
tumor model when the
tumor was under radiation stress. Increased targeting of the fluorescent marker loaded to our
liposomes could be found on the site of
cancer. The liposomal targeting in vivo could be improved by radiation. Based on our studies, we propose
sphingomyelin-containing
liposomes can be used as a controlled release system sensitive to cell stress.