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Low dose radiation induced senescence of human mesenchymal stromal cells and impaired the autophagy process.

Alessio N, Del Gaudio S, Capasso S, Di Bernardo G, Cappabianca S, Cipollaro M, Peluso G, Galderisi U - Oncotarget (2015)

Bottom Line: Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal.We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells.This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination).

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Naples 80138, Italy.

ABSTRACT
Low doses of radiation may have profound effects on cellular function. Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal. We also showed that low radiation affected the autophagic flux. We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells. This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination).

No MeSH data available.


Related in: MedlinePlus

Cell cycle analysis of irradiated MSCPanel (A) – The picture shows representative FACS analysis of irradiated (40 and 2000 mGy) and control MSC. The experiments were carried out six and 48 hours post-irradiation. Experiments were conducted in triplicate for each condition. Percentage of different cell populations (G1, S and G2/M) are indicated. Data are expressed with standard deviation (n = 3, *p < 0.05, **p < 0.01). Panels (B, C) – Representative microscopic field of Ki67 immunostaining (green) on MSC six and 48 hours post-irradiation with 40 and 2000 mGy. Nuclei were counterstained with Hoechst 33342 (blue). Arrows indicate Ki67-positive cells. The graph shows the percentage of Ki67-positive cells. Data are expressed with standard deviation (n = 3, *p < 0.05, **p < 0.01).
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Figure 1: Cell cycle analysis of irradiated MSCPanel (A) – The picture shows representative FACS analysis of irradiated (40 and 2000 mGy) and control MSC. The experiments were carried out six and 48 hours post-irradiation. Experiments were conducted in triplicate for each condition. Percentage of different cell populations (G1, S and G2/M) are indicated. Data are expressed with standard deviation (n = 3, *p < 0.05, **p < 0.01). Panels (B, C) – Representative microscopic field of Ki67 immunostaining (green) on MSC six and 48 hours post-irradiation with 40 and 2000 mGy. Nuclei were counterstained with Hoechst 33342 (blue). Arrows indicate Ki67-positive cells. The graph shows the percentage of Ki67-positive cells. Data are expressed with standard deviation (n = 3, *p < 0.05, **p < 0.01).

Mentions: The cell cycle analysis that we performed six and 48 hours post-irradiation showed that both low and high dose radiation induced a significant reduction of S-phase cells. In detail, 48 hours post-irradiation, we detected 2.6% and 1.9% cells in S-phase in 40 mGy and 2000 mGy treated cells, respectively, as compared to 9.7% in control cultures (Fig. 1A). These data are in good agreement with Ki67 immunostaining that evidenced a significant reduction of cycling cells in low dose irradiated cells compared with healthy cells (19.2% versus 27.1% 48 hours post-irradiation). The high-dose treatment generated a reduction in the number of cycling cells that was higher of that induced by low dose only at 48 hours (Fig. 1B, C). Concordantly, the proliferation rate of 40 and 2000 mGy treated cells was significantly lower than that of the control (Suppl. File 1).


Low dose radiation induced senescence of human mesenchymal stromal cells and impaired the autophagy process.

Alessio N, Del Gaudio S, Capasso S, Di Bernardo G, Cappabianca S, Cipollaro M, Peluso G, Galderisi U - Oncotarget (2015)

Cell cycle analysis of irradiated MSCPanel (A) – The picture shows representative FACS analysis of irradiated (40 and 2000 mGy) and control MSC. The experiments were carried out six and 48 hours post-irradiation. Experiments were conducted in triplicate for each condition. Percentage of different cell populations (G1, S and G2/M) are indicated. Data are expressed with standard deviation (n = 3, *p < 0.05, **p < 0.01). Panels (B, C) – Representative microscopic field of Ki67 immunostaining (green) on MSC six and 48 hours post-irradiation with 40 and 2000 mGy. Nuclei were counterstained with Hoechst 33342 (blue). Arrows indicate Ki67-positive cells. The graph shows the percentage of Ki67-positive cells. Data are expressed with standard deviation (n = 3, *p < 0.05, **p < 0.01).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4480742&req=5

Figure 1: Cell cycle analysis of irradiated MSCPanel (A) – The picture shows representative FACS analysis of irradiated (40 and 2000 mGy) and control MSC. The experiments were carried out six and 48 hours post-irradiation. Experiments were conducted in triplicate for each condition. Percentage of different cell populations (G1, S and G2/M) are indicated. Data are expressed with standard deviation (n = 3, *p < 0.05, **p < 0.01). Panels (B, C) – Representative microscopic field of Ki67 immunostaining (green) on MSC six and 48 hours post-irradiation with 40 and 2000 mGy. Nuclei were counterstained with Hoechst 33342 (blue). Arrows indicate Ki67-positive cells. The graph shows the percentage of Ki67-positive cells. Data are expressed with standard deviation (n = 3, *p < 0.05, **p < 0.01).
Mentions: The cell cycle analysis that we performed six and 48 hours post-irradiation showed that both low and high dose radiation induced a significant reduction of S-phase cells. In detail, 48 hours post-irradiation, we detected 2.6% and 1.9% cells in S-phase in 40 mGy and 2000 mGy treated cells, respectively, as compared to 9.7% in control cultures (Fig. 1A). These data are in good agreement with Ki67 immunostaining that evidenced a significant reduction of cycling cells in low dose irradiated cells compared with healthy cells (19.2% versus 27.1% 48 hours post-irradiation). The high-dose treatment generated a reduction in the number of cycling cells that was higher of that induced by low dose only at 48 hours (Fig. 1B, C). Concordantly, the proliferation rate of 40 and 2000 mGy treated cells was significantly lower than that of the control (Suppl. File 1).

Bottom Line: Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal.We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells.This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination).

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Medicine, Biotechnology and Molecular Biology Section, Second University of Naples, Naples 80138, Italy.

ABSTRACT
Low doses of radiation may have profound effects on cellular function. Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal. We also showed that low radiation affected the autophagic flux. We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells. This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination).

No MeSH data available.


Related in: MedlinePlus