Zur direkten Zytotoxizität von Mistelpräparaten

Author(s): Fiebig, H., Kabelitz, D., Metelmann, H.

Abstract: In vitro as well as in vivo results of direct cytotoxic effects of mistletoe preparations (Viscum album L.) against tumour cell lines and tumour tissue are presented. We investigated mistletoe preparations* containing vesicles of genuine membrane systems in colloidal dispersion (Ø < 200 mm) [1]. The dose dependent cytotoxicity [2, 3, 4] was due to the induction of programmed cell death (apoptosis). Apoptosis was shown by characteristic oligonucleosomal fragmentation of DNA. The programmed cell death was induced by lectins of mistletoe extracts because 1. lectin depleted preparations were some orders of magnitude less effective, 2. the induction of apoptosis in the presence of anti mistletoelectin-1 -antibodies was reduced and 3. purified mistletoelectin 1 (ML1) was active in smallest concentrations (pico- to nano-g-value) [5]. After incubation of stimulated monocytes with mistletoe extracts we found enhanced production of II 1 and TNF *.In other experiments we determined the growth inhibiting effects of mistletoe extracts in 44 different human tumour xenografts using the colony assay. We found great differences between the investigated tumours. Relatively sensitive were lung, breast and testicular cancer xenografts as well as melanomas. But there were also individual differences [6].The in vitro effects of human tumour xenografts were not only due to the lectin content of the extracts, because1. effects of comparable mistletoe extracts, but of different host trees, did not correlate with the lectin content and2. in a direct comparison using 15 patient tumours of head and neck origin Viscum album L. Pini (1/40th of lectin content compared with Viscum album L. Quercus) showed a similar activity than Viscum album L. Quercus [7]).According to the results mentioned above mistletoe extracts were tested in nude mice in in vitro responsive tumours. Intratumoural daily injections (on day 1-3) of established human tumours in nude mice (1 breast-Ca, 1 small cell lung-Ca and 1 melanoma) with a dosage of 0,05 to 0,2 mg mistletoe extract per tumour (ca. 0,6 cm 0) resulted in complete remissions. Systemically treated tumours were not responsive [6]).These results unlock therapeutical prospects which should be proved in clinical studies according to the well documented experience in local treatment of pleuric malignancies [8]. In this case it is necessary to pay attention to the host tree of the used mistletoe on the one hand and to the individual sensibility of tumours on the other hand.

Keyword(s): Mistelpräparate

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