Viscum Album Preparations Research Articles

Vortex-like vs. turbulent mixing of a Viscum album preparation affects crystalline structures formed in dried droplets

Various types of motion introduced into a solution can affect, among other factors, the alignment and positioning of molecules, the agglomeration of large molecules, oxidation processes, and the production of microparticles and microbubbles. We employed turbulent mixing vs. laminar flow induced by a vortex vs. diffusion-based mixing during the production of Viscum album Quercus L. 10−3 following the guidelines for manufacturing homeopathic preparations. The differently mixed preparation variants were analyzed using the droplet evaporation method. The crystalline structures formed in dried droplets were photographed and analyzed using computer-supported image analysis and deep learning. Computer-supported evaluation and deep learning revealed that the patterns of the variant succussed under turbulence are characterized by lower complexity, whereas those obtained from the vortex-mixed variant are characterized by greater complexity compared to the diffusion-based mixed control variant. The droplet evaporation method could provide a relatively inexpensive means of testing the effects of liquid flow and serve as an alternative to currently used methods.

Unsupervised Deep Learning Approach for Characterizing Fractality in Dried Drop Patterns of Differently Mixed Viscum album Preparations

This paper presents a novel unsupervised deep learning methodology for the analysis of self-assembled structures formed in evaporating droplets. The proposed approach focuses on clustering these structures based on their texture similarity to characterize three different mixing procedures (turbulent, laminar, and diffusion-based) applied to produce Viscum album Quercus 10−3 according to the European Pharmacopoeia guidelines for the production of homeopathic remedies. Texture clustering departs from obtaining a comprehensive texture representation of the full texture patch database using a convolutional neural network. This representation is then dimensionally reduced to facilitate clustering through advanced machine learning techniques. Following this methodology, 13 clusters were found and their degree of fractality determined by means of Local Connected Fractal Dimension histograms, which allowed for characterization of the different production modalities. As a consequence, each image was represented as a vector in R13, enabling classification of mixing procedures via support vectors. As a main result, our study highlights the clear differences between turbulent and laminar mixing procedures based on their fractal characteristics, while also revealing the nuanced nature of the diffusion process, which incorporates aspects from both mixing types. Furthermore, our unsupervised clustering approach offers a scalable and automated solution for analyzing the databases of evaporated droplets.

In-Vitro Growth Kinetics of Mesenchymal Stem Cells in Cytotoxicity Tests Using Low-Diluted Viscum Album.

The use of mesenchymal stem cells (MSC) in cytotoxicity tests is an in-vitro alternative model for predicting initial doses. Homeopathic medicines may stimulate the immune system to combat a pathology effectively and have been used for over two centuries. Viscum album (VA) extracts are widely used in the treatment of cancer, due to their immunomodulatory, cytotoxic and pro-apoptotic properties. This study aimed to evaluate the in-vitro growth kinetics of canine MSC in relation to cytotoxicity, cell differentiation and expression of pluripotentiality markers, using a VA preparation at the D1D2 (1×10-1, 1×10-2 potency (VAD1D2). MSC were obtained from adipose tissue sampled from a healthy dog that was undergoing an elective veterinary procedure and with its owner's permission. The experiments were performed in three groups: MSC treated with VAD1D2 or diluent or untreated (control). The cytotoxicity was evaluated by MTT assay. The differentiation was induced in three lineages, and apoptotic cell labeling was performed by an Annexin-V test. At the concentration of 10 μL/mL of VA, the number of cells after in-vitro culture was maintained when compared with the control (untreated) group. A significant and gradual decrease in cell viability was recorded as VA concentrations increased. The apoptosis analysis showed that VA at 20 μL/mL presented absolute percentages of initial apoptosis twice as high as at 10 μL/mL, which was similar to the control (untreated group). The results suggest that the use of efficient methods to assess the in-vitro cytotoxicity of VA-based homeopathic medicines using MSC lineages may predict the potential action at different concentrations. These findings demonstrated that VAD1D2 interferes with canine MSC growth kinetics.

Antitumoral activity of homeopathic and anthroposophic Viscum album's preparations: an in vitro assay

Background: Viscum album (mistletoe) has been used for a variety of purposes and is widely used as an alternative treatment for cancer and other diseases. Preparations of fermented extracts from Viscum album (VA), a plant from the Loranthaceae family, have been used, mainly in European countries, with promising results as adjuvant therapies, especially in Anthroposophic Medicine.1,2,3. In vitro studies have demonstrated that various types of VA may have cytotoxic activity in carcinoma cells, being able to activate the apoptotic cascade or leading cells to necrosis. It is possible to prepare VA extracts using different procedures and solvents. The homeopathic preparations involve the use of ethanol as solvent4, while the antroposophic preparations are obtained in aqueous solvent5. 
 Aims: The present study aimed to verify the cytotoxic effects of homeopathic and anthroposophic Viscum album preparations in human leukaemic K562 cell line. 
 Methodology: The cytotoxic effects of anthroposophic (ISCADOR A - IA; ISCADOR P - IP; ISCADOR M - IM; ISCADOR U - IU; ISCADOR Qu - IQu) and homeopathic Viscum album extracts (VA) were evaluated in K562 cells. For this, ten independent experiments of Trypan blue assay and five independent MTT assay were carried out.6 Additionally, cell morphology was analysed by phase inverted contrast microscopy coupled to digital camera (Optika XDS-3).7 The results were expressed as mean±SD, and statistical comparisons were performed by one-way ANOVA. 
 Results: All samples tested were able to interfere with viability and mitochondrial activity, with important morphological damage, when compared to respective controls. Considering the ISCADOR samples all of them presented similar cytotoxic activity, with lower activity attribute to IP (around 25% of viable cells) in comparison to 90% of non-viable cells induced by other samples. The homeopathic preparation originated the best results compared to anthroposophic samples. Morphological analyses supported the MTT and trypan blue assays´ results. 
 Conclusion: The anticancer activity tested in K562 indicate that all Viscum album samples have anticancer activity, in a dose dependent manner. Further tests need to be done in order to contribute for the understanding of the Viscum album antitumoral mechanisms, as well as about differences between homeopathic and antroposophic procedures.

Viscum album : from high dilutions to phytotherapy

Background : Besides conventional anticancer therapy, cancer patients use complementary and alternative medicine like the medicinal herb mistletoe (Viscum album L.), used in oral form or injections.
 For this condition Viscum album (VA) is also used in high dilutions, in injections, as in Brazil.
 
 Aim:
 Our aim is to compare results of basic research about these two presentations: herbal medicine and high dilutions and to look for an eventual continuity of action between the molecular form (herbal medicine) and the informative one (high dilutions)
 
 Method:
 About VA in herbal medicine : a lot of references in immunology, in particular those published by the team of Srini Kaveri and Stephan Baumgartner.(1) (2) (3) (4) (5)
 About VA in high dilutions : the work in immunology of Aloiso Cunha de Carvalho and Leoni Bonamin published in a thesis. (6)
 And then to compare those results with our practice as veterinarian on dogs and cats .
 
 Results : 
 VA in herbal medecine: from basic research results, we know that in low concentration, 
 an immunostimulary action is observed while in higher doses it is a cytotoxic activity.
 These two properties are found in our practical use of VA in dogs or cats : stabilization of the size of tumors for the low concentrations, necrosis of tumors and abscess for the high concentrations. 
 VA in high dilutions (from D3 to D30) : from basic research, an immunostimutating effect is observed. More exactly, on a murin model of tumor of Ehrlich, it is observed an improvement of quality of life, a reduction of the tumor immunosuppressive effect, an enlargement of local inflammations (Oedema) for all concentrations, but only 3D reduces tumor growth, without modifying local necrosis and the immunological parameters.
 In our practice, on two cases of osteosarcoma on dogs, we verify those properties using VA both in herbal medicine and in high dilutions. 
 
 Conclusions:
 From these results, both in basic research and in the practice, we should estimate there is probably a continuity of action fom VA, in High Dynamised Dilutions ( no more molecule), to VA in herbal medicine (molecular activity). From immunostimation to cytotoxicity, from information to molecular activity.
 
 Does each Viscum album’s preparation touch
 the same level of the Immune System ? The same cells ? The same receptors ? A lot of questions remain…
 
 
 References 
 
 
 1) Duong Van Huyen JP and al. Variable sensitivity of lymphoblastoid cells to apoptosis induced by Viscum album Qu FrF, a therapeutic preparation of mistletoe lectin. Chemotherapy. (2001)
 
 2) Duong Van Huyen JP and al. Induction of apoptosis of endothelial cells by Viscum album: a role for anti-tumoral properties of mistletoe lectins. Mol Med. (2002)
 
 3)Duong Van Huyen JP and al Comparative study of the sensitivity of lymphoblastoid and transformed monocytic cell lines to the cytotoxic effects of Viscum album extracts of different origin.. Chemotherapy. (2003)
 
 4) Estko M and al. Tumour cell derived effects on monocyte/macrophage polarization and function and modulatory potential of Viscum album lipophilic extract in vitro.
 BMC Complement Altern Med. 2015
 
 
 5) Saha C, and al Differential Effects of Viscum album Preparations on the Maturation and Activation of Human Dendritic Cells and CD4⁺ T Cell Responses.
 Molecules. 2016 Jul 14;21(7)
 
 6) Aloisio Cunha de Carvalho , ATIVIDADE ANTI-NEOPLÁSICA DE Viscum album (L) EM TUMORES EXPERIMENTAIS: REVISÃO CRÍTICA E ESTUDO EXPERIMENTAL EM TUMOR DE EHRLICH, Thesis Sao Paulo

Homoeopathic Viscum album extract inhibits the growth of osteosarcoma cells

Objectives: This study is aimed to evaluate the cytotoxic action of two homoeopathic medicines that are derived from Viscum album (VA) extract. Materials and Methods: An osteosarcoma cell line was cultured in the presence of two homoeopathic VA preparations (VAD3 and VAD30) and cell viability was evaluated using MTT assay. The cell line U-2 OS was plated in two 96-well plates for 24 h with culture medium at 37 5°C and 5% CO2. Subsequently, this medium was replaced by another one containing VAD3 and VAD30 separately in concentrations ranging from 10 to 100 μL/mL, as well as a control group (culture medium only). These plates were kept in culture for 48 h. MTT assay was performed to evaluate the percentage of viable cells. Subsequently, concentrations ranging from 1 to 10 μL/mL were tested. Results were compared to those of the control group and the mean half maximal inhibitory concentration (IC50) was calculated. Results: The MTT assay showed that it is possible to reduce 50% of the osteosarcoma cell population with low concentrations of the homeopathic VAD3 and VAD30 with IC50 of 6 62 μL/mL and 5 82 μL/mL, respectively. Conclusion: This is a promising result that shows the action of VAD3 and VAD30 in the U-2 OS lineage of osteosarcoma cancer cells. This opens up the possibility of using this medicine in the treatment of these tumours; if not alone, at least in association with other medicines or techniques.

Antiproliferative potential from aqueous Viscum album L. preparations and their main constituents in comparison with ricin and purothionin on human cancer cells

Ethnopharmacological relevanceMistletoe has been used since ancient times in Europe mostly for medicinal purposes. Since 1917, mistletoe preparations have been applied in cancer therapy and today are the most frequently used complementary medicine in tumor treatment. The main cytotoxic constituents of Viscum album are lectins and viscotoxins. Aim of the studyThe aim of this in vitro study was to investigate the antiproliferative potential of Viscum album preparations from different host trees and to assess the impact of mistletoe lectin 1 (ML-1) and viscotoxin A (VT-A) in comparison to a structurally similar lectin and thionin. Materials and methodsBy means of widely accepted 2D Alamar Blue Assay, based on population counting of living cells using a fluorescent cell viability dye, the potential impact to inhibit tumor cell of the mistletoe preparations (Iscucin®) and their single compounds (ML-1 and VT-A) on the cell growth of six human cancer cell lines were evaluated. Also the mixture of ML-1 and VT-A corresponding to the contents in the specific mistletoe preparations were monitored. Ricin and purothionin were used as reference lectin and reference thionin, respectively. ResultsThe lung carcinoma cell line HCC827 was very sensitive to the Iscucin® preparations. Very strong antiproliferative effects were found with Iscucin®Salicis and Tiliae and a strong with Iscucin®Crataegi, Mali and Populi. The IC50 concentrations of the Iscucin® preparations correlated with their respective ML-1 contents, but the ML-1 levels were much lower than the IC50 concentration of isolated ML-1 (1 ng/ml – 56 ng/ml). ML-1 was much more effective than ricin. Iscucin® preparations, ML-1 and ricin showed antiproliferative activity on human tumor cells. VT-A and purothionin had no effect on cell viability in the concentration ranges tested. ConclusionThe complete mistletoe extract is more potent to inhibit tumor cell proliferation than isolated ML-1 at an equivalent concentration level. Phenolic compounds found in all Iscucin® preparations might contribute to uphold the cytotoxic activity of ML-1 by antioxidative action. However, further studies are necessary to evaluate the role of VT-A and possible synergistic actions to the antiproliferative effect of aqueous mistletoe extracts.

Differential Effects of Viscum album Preparations on the Maturation and Activation of Human Dendritic Cells and CD4⁺ T Cell Responses.

Extracts of Viscum album (VA); a semi-parasitic plant, are frequently used in the complementary therapy of cancer and other immunological disorders. Various reports show that VA modulates immune system and exerts immune-adjuvant activities that might influence tumor regression. Currently, several therapeutic preparations of VA are available and hence an insight into the mechanisms of action of different VA preparations is necessary. In the present study, we performed a comparative study of five different preparations of VA on maturation and activation of human dendritic cells (DCs) and ensuing CD4+ T cell responses. Monocyte-derived human DCs were treated with VA Qu Spez, VA Qu Frf, VA M Spez, VA P and VA A. Among the five VA preparations tested VA Qu Spez, a fermented extract with a high level of lectins, significantly induced DC maturation markers CD83, CD40, HLA-DR and CD86, and secretion of pro-inflammatory cytokines such as IL-6, IL-8, IL-12 and TNF-α. Furthermore, analysis of T cell cytokines in DC-T cell co-culture revealed that VA Qu Spez significantly stimulated IFN-γ secretion without modulating regulatory T cells and other CD4+ T cytokines IL-4, IL-13 and IL-17A. Our study thus delineates differential effects of VA preparations on DC maturation; function and T cell responses.

Pre-clinical and clinical investigations on Viscum album preparations

Pre-clinical and clinical investigations on Viscum album preparations

Investigation of the impact of Viscum album preparations on the proliferation of the equine sarcoid cell line E42/02

Investigation of the impact of Viscum album preparations on the proliferation of the equine sarcoid cell line E42/02

Viscum album-mediated COX-2 inhibition implicates destabilization of COX-2 mRNA.

Extensive use of Viscum album (VA) preparations in the complementary therapy of cancer and in several other human pathologies has led to an increasing number of cellular and molecular approaches to explore the mechanisms of action of VA. We have recently demonstrated that, VA preparations exert a potent anti-inflammatory effect by selectively down-regulating the COX-2-mediated cytokine-induced secretion of prostaglandin E2 (PGE2), one of the important molecular signatures of inflammatory reactions. In this study, we observed a significant down-regulation of COX-2 protein expression in VA-treated A549 cells however COX-2 mRNA levels were unaltered. Therefore, we hypothesized that VA induces destabilisation of COX-2 mRNA, thereby depleting the available functional COX-2 mRNA for the protein synthesis and for the subsequent secretion of PGE2. To address this question, we analyzed the molecular degradation of COX-2 protein and its corresponding mRNA in A549 cell line. Using cyclohexamide pulse chase experiment, we demonstrate that, COX-2 protein degradation is not affected by the treatment with VA whereas experiments on transcriptional blockade with actinomycin D, revealed a marked reduction in the half life of COX-2 mRNA due to its rapid degradation in the cells treated with VA compared to that in IL-1β-stimulated cells. These results thus demonstrate that VA-mediated inhibition of PGE2 implicates destabilization of COX-2 mRNA.

Effects of mistletoe extract on markers of platelet activation and aggregation

BACKGROUND: Viscum album preparations are extensively used as complementary therapy in cancer and are shown to exert antitumor activities which involve the cytotoxic properties, induction of apoptosis, inhibition of angiogenesis and several other immunomodulatory mechanisms. AIM: The aim of this study was to investigate the effects of mistletoe extract on platelet as well as monocyte functions, as an important factors in immunomodulation of cancers metastatic potencial and angiogenesis in tumors. METHODS: The effect of different concentrations of mistletoe extract on agonist-induced platelet activation markers and their aggregation with leukocytes was examined in the blood of healthy subjects (n=6) using flow cytometry. Effects on LPS -induced activation markers was determined in the blood of healthy subjects as well as on THP-1 cell line using an ELISA essays and flow cytometry. RESULTS: Mistletoe extract significantly inhibited agonist induced P selectin expression and platelet-monocytes aggregation. Additionally, mistletoe extract exerts anti-tumor effect through the stimulation of TNF-? production in LPS induced monocytes activation. CONCLUSION: Obtained data demonstrate that mistletoe extract was effective in modulating platelet and monocyte functions, as a part of pleiotropic anticancer effect.

Difficulties and perspectives of immunomodulatory therapy with mistletoe lectins and standardized mistletoe extracts in evidence based medicine

Viscum album preparations are aqueous mistletoe plant extracts used in complementary and alternative medicine as immunomodulators in cancer therapy. However, evidence of immunological efficacy of mistletoe extracts (MEs) used in clinical trials is often lacking. Mechanisms involved in anti-tumor properties of ME and mistletoe lectins (MLs) modify both innate and adaptive immune systems, according to animal model experiments. In the background of these effects, a selective binding of ML on CD75 ganglioside receptors of interleukin 12 (IL-12)-producing macrophages or dendritic cells can play an important role. Immunological effects of ME correlate with their lectin activity, showing a bell-shaped dose-response curve of efficacy. Therefore, a correct determination of MLs for the standardization of commercial ME is essential. However, plant MLs exhibit heterogeneity, which most likely results from post-translational processing. In addition, amino acid analysis of ML has revealed numerous conservative substitutions along their amino acid sequence. Consequently, ML research needs new perspectives, and the advantages and disadvantages of purified and biologically better defined ML preparations are also discussed in this article.

Viscum album Exerts Anti-Inflammatory Effect by Selectively Inhibiting Cytokine-Induced Expression of Cyclooxygenase-2

Viscum album (VA) preparations are extensively used as complementary therapy in cancer and are shown to exert anti-tumor activities which involve the cytotoxic properties, induction of apoptosis, inhibition of angiogenesis and several other immunomodulatory mechanisms. In addition to their application in cancer therapy, VA preparations have also been successfully utilized in the treatment of several inflammatory pathologies. Owing to the intricate association of inflammation and cancer and in view of the fact that several anti-tumor phytotherapeutics also exert a potent anti-inflammatory effect, we hypothesized that VA exerts an anti-inflammatory effect that is responsible for its therapeutic benefit. Since, inflammatory cytokine-induced cyclo-oxygenase-2 (COX-2) and prostaglandin E2 (PGE2) play a critical role in the pathogenesis of inflammatory diseases, we investigated the anti-inflammatory effect of VA on regulation of cyclo-oxygenase expression and PGE2 biosynthesis by using human lung adenocarcinoma cells (A549 cells) as a model. A549 cells were stimulated with IL-1β and treated with VA preparation (VA Qu Spez) for 18 hours. PGE2 was analysed in the culture supernatants by enzyme immunoassay. Expression of COX-2 and COX-1 proteins was analyzed by immunoblotting and the expression of COX-2 mRNA was assessed by semi-quantitative RT-PCR. We found that VA Qu Spez inhibit the secretion of IL-1β-induced PGE2 in a dose-dependent manner. Further, we also show that this inhibitory action was associated with a reduced expression of COX-2 without modulating the COX-1 expression. Together these results demonstrate a novel anti-inflammatory mechanism of action of VA preparations wherein VA exerts an anti-inflammatory effect by inhibiting cytokine-induced PGE2 via selective inhibition of COX-2.

Difficulties and Perspectives of Immunomodulatory Therapy with Mistletoe Lectins and Standardized Mistletoe Extracts in Evidence‐Based Medicine

Viscum album preparations are aqueous mistletoe plant extracts used in complementary and alternative medicine as immunomodulators in cancer therapy. However, evidence of immunological efficacy of mistletoe extracts (MEs) used in clinical trials is often lacking. Mechanisms involved in anti-tumor properties of ME and mistletoe lectins (MLs) modify both innate and adaptive immune systems, according to animal model experiments. In the background of these effects, a selective binding of ML on CD75 ganglioside receptors of interleukin 12 (IL-12)-producing macrophages or dendritic cells can play an important role. Immunological effects of ME correlate with their lectin activity, showing a bell-shaped dose-response curve of efficacy. Therefore, a correct determination of MLs for the standardization of commercial ME is essential. However, plant MLs exhibit heterogeneity, which most likely results from post-translational processing. In addition, amino acid analysis of ML has revealed numerous conservative substitutions along their amino acid sequence. Consequently, ML research needs new perspectives, and the advantages and disadvantages of purified and biologically better defined ML preparations are also discussed in this article.

Regulatory options for viscum album preparations

Regulatory options for viscum album preparations

Mistletoe lectin is not the only cytotoxic component in fermented preparations of Viscum album from white fir (Abies pectinata)

BackgroundPreparations of mistletoe (Viscum album) are the form of cancer treatment that is most frequently used in the complementary medicine. Previous work has shown that these preparations are able to exert cytotoxic effects on carcinoma cells, the extent of which might be influenced by the host tree species and by the content of mistletoe lectin.MethodsUsing colorimetric assays, we have now compared the cytotoxic effects of Viscum album preparations (VAPs) obtained from mistletoe growing on oak (Quercus robur and Q. petraea, VAP-Qu), apple tree (Malus domestica,, VAP-M), pine (Pinus sylvestris, VAP-P) or white fir (Abies pectinata, VAP-A), on the in vitro growth of breast and bladder carcinoma cell lines. While MFM-223, KPL-1, MCF-7 and HCC-1937 were the breast carcinoma cell lines chosen, the panel of tested bladder carcinoma cells comprised the T-24, TCC-SUP, UM-UC-3 and J-82 cell lines.ResultsEach of the VAPs inhibited cell growth, but the extent of this inhibition differed with the preparation and with the cell line. The concentrations of VAP-Qu, VAP-M and VAP-A which led to a 50 % reduction of cell growth (IC50) varied between 0.6 and 0.03 mg/ml. Higher concentrations of VAP-P were required to obtain a comparable effect. Purified mistletoe lectin I (MLI) led to an inhibition of breast carcinoma cell growth at concentrations lower than those of VAPs, but the sensitivity towards purified MLI did not parallel that towards VAPs. Bladder carcinoma cells were in most cases more sensitive to VAPs treatment than breast carcinoma cells. The total mistletoe lectin content was very high in VAP-Qu (54 ng/mg extract), intermediate in VAP-M (25 ng/mg extract), and very low in VAP-P (1.3 ng/mg extract) and in VAP-A (1 ng/mg extract). As to be expected from the low content of mistletoe lectin, VAP-P led to relatively weak cytotoxic effects. Most remarkably, however, the lectin-poor VAP-A revealed a cytotoxic effect comparable to, or even stronger than, that of the lectin-rich VAP-Qu, on all tested bladder and breast carcinoma cell lines.ConclusionThe results suggest the existence of cytotoxic components other than mistletoe lectin in VAP-A and reveal an unexpected potential of this preparation for the treatment of breast and bladder cancer.

Interleukin-12 is associated with the in vivo anti-tumor effect of mistletoe extracts in B16 mouse melanoma

Viscum album (VA) preparations consist of aqueous extracts of different types of lectins of mistletoe. VA exert cytotoxic and immunomodulatory properties that may be relevant for the inhibition of tumor growth. We addressed the effects of VA preparation VA Qu FrF on growth of B16F1 melanoma implanted in mice and on proliferation and cytokine synthesis of splenocytes. In C57BL6 mice, inhibition of tumor growth by VA was associated with an enhancement of splenocyte proliferation and with an up-regulation of IL-12 secretion. In IL-12-deficient strain of mice the inhibition of melanoma growth by VA and the splenocyte proliferation were abrogated. Results from the present study strongly suggest a crucial role of IL-12 in the anti-tumor properties of VA extracts.

Comparative Study of the Sensitivity of Lymphoblastoid and Transformed Monocytic Cell Lines to the Cytotoxic Effects of Viscum album Extracts of Different Origin

Viscum album (VA) preparations consist of aqueous extracts of V. album, the European mistletoe. VA extracts contain mistletoe lectins, which are members of the ribosome-inactivating protein type II family. VA preparations have cytotoxic and immunomodulatory properties. Cytotoxicity induced by VA extracts may differ greatly according to the origin of the preparation (host tree, fermented extract) and the cell type. This work was performed to assess the cytotoxicity of various VA preparations, i.e. VA Qu FrF, Qu Spez, M Spez and VA P, in lymphoblastoid and monocytic cell lines. VA Qu FrF, Qu Spez and M Spez induced dose-dependent cell death and inhibition of cell proliferation in lymphoblastoid T cell lines and in transformed monocytic lines. In contrast, the majority of B cell lines tested were resistant to cytotoxicity induced by VA extracts. While VA Qu FrF, Qu Spez and M Spez were potent inducers of cell death, extracts of VA P, derived from mistletoe plants growing on pine trees, failed to induce any cell death in any of the cell lines examined.

Induction of Apoptosis of Endothelial Cells by Viscum album: A Role for Anti-Tumoral Properties of Mistletoe Lectins

Viscum album (VA) preparations consist of aqueous extracts of different types of lectins of VA. Mistletoe lectins have both cytotoxic and immunomodulatory properties that support their study for the development for cancer therapy. However, the mechanisms of the anti- tumoral properties in vivo of mistletoe lectins are not fully understood. Because endothelial cells (EC) play a pivotal role in tumor angiogenesis, we tested the hypothesis that VA extracts induce endothelial cell death and apoptosis. We investigated the effect of various VA preparations on both human venous endothelial cell (HUVEC) and immortalized human venous endothelial cell line (IVEC) using morphologic assessment of EC, FACScan analysis after propidium iodine and annexin V labeling, and detection of cleavage of poly(A)DP-ribose polymerase (PARP). All tested VA preparations, except Iscador P, were cytotoxic in IVEC. Apoptosis, assessed by morphologic examination, annexin V labeling, and Western blot analysis for PARP cleavage, was involved in HUVEC cell death induced by VA preparations derived from plants that grow on oak trees (VA Qu FrF). Results from the present study suggest that VA extract-induced endothelial apoptosis may explain the tumor regression associated with the therapeutic use of VA preparations and support further investigations to develop novel anti-angiogenic compounds based on mistletoe compounds.