The radiation-induced bystander effect (bystander effect) is the phenomenon in which unirradiated cells exhibit irradiated effects as a result of signals received from nearby irradiated cells. In November 1992, Hatsumi Nagasawa and John B. Little first reported this radiobiological phenomenon. [1]
There is evidence that targeted cytoplasmic irradiation results in mutation in the nucleus of the hit cells. [2] [3] Cells that are not directly hit by an alpha particle, but are in the vicinity of one that is hit, also contribute to the genotoxic response of the cell population. [4] [5] Similarly, when cells are irradiated, and the medium is transferred to unirradiated cells, these unirradiated cells show bystander responses when assayed for clonogenic survival and oncogenic transformation. [6] [7] This is also attributed to the bystander effect.
The demonstration of a bystander effect in 3D human tissues [8] and, more recently, in whole organisms [9] have clear implication of the potential relevance of the non-targeted response to human health.
This effect may also contribute to the final biological consequences of exposure to low doses of radiation. [10] [11] However, there is currently insufficient evidence to suggest that the bystander effect promotes carcinogenesis in humans at low doses. [12]
Note that the bystander effect is not the same as the abscopal effect. The abscopal effect is a phenomenon where the response to radiation is seen in an organ/site distant to the irradiated organ/area, that is, the responding cells are not juxtaposed with the irradiated cells. T-cells and dendritic cells have been implicated to be part of the mechanism. [13]
In suicide gene therapy, the "bystander effect" is the ability of the transfected cells to transfer death signals to neighboring tumor cells. [14]
The radiation-induced bystander effect (bystander effect) is the phenomenon in which unirradiated cells exhibit irradiated effects as a result of signals received from nearby irradiated cells. In November 1992, Hatsumi Nagasawa and John B. Little first reported this radiobiological phenomenon. [1]
There is evidence that targeted cytoplasmic irradiation results in mutation in the nucleus of the hit cells. [2] [3] Cells that are not directly hit by an alpha particle, but are in the vicinity of one that is hit, also contribute to the genotoxic response of the cell population. [4] [5] Similarly, when cells are irradiated, and the medium is transferred to unirradiated cells, these unirradiated cells show bystander responses when assayed for clonogenic survival and oncogenic transformation. [6] [7] This is also attributed to the bystander effect.
The demonstration of a bystander effect in 3D human tissues [8] and, more recently, in whole organisms [9] have clear implication of the potential relevance of the non-targeted response to human health.
This effect may also contribute to the final biological consequences of exposure to low doses of radiation. [10] [11] However, there is currently insufficient evidence to suggest that the bystander effect promotes carcinogenesis in humans at low doses. [12]
Note that the bystander effect is not the same as the abscopal effect. The abscopal effect is a phenomenon where the response to radiation is seen in an organ/site distant to the irradiated organ/area, that is, the responding cells are not juxtaposed with the irradiated cells. T-cells and dendritic cells have been implicated to be part of the mechanism. [13]
In suicide gene therapy, the "bystander effect" is the ability of the transfected cells to transfer death signals to neighboring tumor cells. [14]