Lysosomotropic carrier polymers

The first example is a so called lysosomotropic (5) carrier polymer(6). There are tumour cells which are resistant to metho-trexate (MTX), a folate antagonist widely used in tumour chemotherapy. It was assumed that these cells lack the appropriate transport system for MTX. If the drug is covalently bound to poly-L-or D-Lysin, it is readily internalized by resistant and non-resistant tumour cells via endocytosis (a process similar to engulfment of food by amoebae). Yet, only the L-polymer acts cytostatically. In contrast to the D-polymer, it can be degraded in the lysosomes of the cell - the place where endocytosed material goes. So the "lysosomotropic vector" poly-L-Lysin is a good example for the ability of many polymers to enter cells via endocytosis and for the importance of polymer stereochemistry. 

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