| Abstract |
Autologous bone marrow transplantation is a therapeutic modality that increases the survival rates for children with poor prognosis malignancies but relapse rates are high and attributed partially to the existence of residual malignant cells. The photodynamic treatment (PDT) has been developed among purging strategies. In this study we investigated the effect of the methanolic extract (ME) and its fraction (PMF) of Hypericum perforatum L. (St. Johns wort), as a new photosensitizer on the leukemic cell line HL-60 and cord blood hemopoietic progenitors. The subcellular localization of the photosensitizer was also investigated with non linear and confocal microscopy. Cells were incubated with the PMF or ME for one hour before irradiation with Laser at 532nm. The concentrations of PMF or ME used were 30, 40, 50 and 60 μg/ml. Each of them was tested at 3, 5, 7 minutes of irradiation (74.87, 124.79, 174.7 J/cm2 respectively). Laser photoirradiation in the presence of both PMF and ME induces the killing of HL-60 cells. This effect is dose dependent. At all the tested irradiation doses and photosensitizer concentrations a 99.9999% cell death was observed 24 hrs after irradiation but only concentrations of 50 and 60 μg/ml of PMF or ME resulted in cell killing at the end of the culture. No colony growth from cord blood mononuclear cells was observed under the tested experimental conditions. There was not cell death when cells were incubated only with PMF or ME without irradiation. The extracts were found to localize in the cytoplasm. PDT with both PMF and ME induces the killing of HL-60 leukemic cells and the optimal conditions of treatment were determined. This effect of PDT/ PMF was also exerted on cord blood progenitor cells indicative of the non selective uptake of the photosensitizer by malignant cells. Though this suggests that PDT/ PMF cannot be helpful in autologous bone marrow purging, PMF can however be beneficial in the PDT treatment of tumors.
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Φωτοδυναμική θεραπεία (PDT) παρουσία εκχυλίσματος του Hypericum Perforatum L ως φωτοευαισθητοποιητή για την επίτευξη θανάτωσης των κυττάρων της HL-60 λευχαιμικής σειράς
