Objective To establish a human intestinal organ-on-a-chip model using a multi-array chip array to simulate the microphysiological structure of the human intestine and to investigate the impact of ionizing radiation on radiation-induced damage to human intestinal cells.Methods Caco-2 and human umbilical vein endothelial cells(HUVECs)were co-cultured in an organ chip.The cells were subjected to fluid shear stress via a precision shaker.After 7 days of dynamic culture,the morphological structure of intestinal epithelial cells and venous endothelial cells within the intestinal organ chip was examined using phase contrast microscopy,immunofluorescence staining,and confocal microscopy for three-dimensional(3D)imaging.γ-H2AX and TUNEL immunofluorescence staining were employed to assess DNA damage and apoptosis in intestinal epithelial cells two days post-irradiation.Villin immunofluorescence staining was used to evaluate villus height three days post-irradiation.EdU incorporation assay and Ki67 immunofluorescence staining were conducted to observe the effects of ionizing radiation on the proliferation of intestinal epithelial cells.Results After 7 days of dynamic culture,phase contrast microscopy and immunofluorescence staining combined with confocal 3D imaging revealed that the upper intestinal epithelial cells in the middle compartment of the chip formed a 3D intestinal villus structure,while the vascular endothelial cells in the lower compartment developed a vascular network structure.The chip was subsequently irradiated by 10 Gy X-ray.Immunofluorescence staining results indicated that the mean fluorescence intensity of γ-H2AX and TUNEL in the irradiated group was significantly higher than in the non-irradiated group 2 days after irradiation(P＜0.01),and that the proportion of EDU+and Ki67+cells in the irradiated group was significantly lower than in the non-irradiated group three days after irradiation(P＜0.05).Conclusion Caco-2 cells and HUVECs co-culture on an organ chip can generate the biomimetic structure of human intestinal villus.Ionizing radiation has been found to shorten intestinal villus,increase DNA damage and apoptosis in intestinal epithelial cells,and inhibit the proliferation of these cells.

Objective To investigate the protective effect and mechanism of CDK4/6 inhibitor palbociclib against radiation-induced injury in rats'small intestinal crypt epithelial cell line(IEC-6).Methods(1)Using CCK-8 colorimetric assay,colony formation assay,the PI staining method,Annexin V-FITC/PI dual staining and Western blot,the impact of palbociclib on proliferation,cell cycle dynamics,apoptosis,DNA damage,as well as phosphorylation events at Rb-780 and 795 sites in irradiated IEC-6 cells was investigated.(2)An IEC-6 cell line overexpressing Rb was established,and the effects of Rb overexpression on proliferation,cell cycle,and apoptosis in the IEC-6 cell line were assessed using the CCK-8 colorimetric assay,PI staining method,Annexin V-PE/7-AAD dual staining and Western blot.Additionally,the impact of Rb overexpression on the protective effect of palbociclib against radiation damage was verified in the Rb-overexpressing IEC-6 cell line.Results(1)Administration of palbociclib was demonstrated to enhance the proliferative capacity of IEC-6 cells following exposure to 10 Gy X-ray irradiation,increase colony formation ability post 4-8 Gy X-ray exposure while concomitantly reducing the proportion of cells in the G2/M phase after 10 Gy irradiation and diminishing apoptosis in irradiated IEC-6 cells.Protein expression analysis revealed that palbociclib inhibited phosphorylation at Rb-780 and 795 sites and attenuated the production of γ-H2AX in IEC-6 cells following irradiation.(2)After transfection of IEC-6 cells with Rb overexpression lentivirus,there was a significant increase in the total protein expression of Rb.The phosphorylation levels at Rb-780 and 795 sites were markedly elevated.Consequently,cell proliferation was accelerated,the proportion of cells in the S phase of the cell cycle increased,and the apoptotic rate significantly rose after exposure to 10 Gy X-ray irradiation.(3)Treatment with a lower dose of palbociclib(0.05 μmol/L)was found to suppress the phosphorylation of Rb at 780 and 795 sites in IEC-6 cells overexpressing Rb.Additionally,it reduced apoptosis in IEC-6 cells overexpressing Rb following exposure to 10 Gy X-ray irradiation.However,this treatment did not inhibit the phosphorylation of Rb at 780 and 795 sites in IEC-6 cells transfected with the empty vector,nor did it exert a protective effect against radiation-induced damage in these cells.Conclusion The CDK4/6 inhibitor palbociclib demonstrates significant protective effects against radiation-induced damage in rats'intestinal crypt epithelial cell line(IEC-6),with the Rb protein potentially playing a crucial role in mediating this radioprotective response.

Acute radiation sickness(ARS)is a systemic syndrome caused by exposure to large doses of radiation in a single or short period of time.Hematopoietic tissue injury is the basic injury in case of acute radiation sickness.Romiplostim(RP)is a thrombopoietin receptor agonist that promotes platelet production by stimulating bone marrow megakaryocytes.In recent years,studies have shown that RP has a significant effect on acute radiation sickness,and has been approved by the United States Food and Drug Administration(FDA)for the treatment of bone marrow acute radiation sickness.In this paper,the recent research progress in the treatment of acute radiation sickness with romiplostim is reviewed.

OBJECTIVE To explore the role and mechanism of dental pulp stem cells(DPSCs)in repairing hypoxic injury to rats pulmonary microvascular endothelial cells(PMVECs).METHODS ①PMVECs were treated with cobalt chloride at 0,10,25,50 and 100 μmol·L-1 for 72 h.CCK-8 was used to detect the cell viability,and the protein levels of hypoxia-inducible factor 1α(HIF-1α),zona occludens small-band protein 1(ZO-1),and occludin(OCLN)were detected by Western blotting.②There was a cell control group,model group,and model+DPSCs group,and the levels of reactive oxygen species(ROS)was detected by immunofluorescence staining after at 24 and 48 h of action.The levels of ZO-1 and OCLN proteins were detected by Western blotting.③ A cell control group,model group,model+DPSC group and model+DPSC cell knockdown superoxide dismutase 1(SOD1)group were set up.The mRNA level of SOD1 was detected by real-time fluorescence quantitative PCR 24 and 48 h later,while the protein levels of ZO-1 and OCLN were detected by Western blotting.RESULTS ① Com-pared with the cell control group,72 h of cobalt chloride 100 μmol·L-1 treatment of PMVECs resulted in a cell survival rate above 80%,a significant increase in the level of HIF-1α protein(P<0.05),a signifi-cant decrease in the levels of ZO-1 and OCLN proteins(P<0.01),and establishment of a model of hypoxic injury in PMVECs.② Compared with the cell control group,the ROS level was significantly higher in the model group(P<0.01).Compared with the model group,the ROS level was significantly lower in the model+DPSCs group(P<0.01),while the levels of ZO-1 and OCLN proteins were signifi-cantly higher in the model+DPSCs group(P<0.05).③ Compared with the DPSC group,ZO-1 and OCLN expressions were significantly decreased after knockdown of SOD1 in DPSCs(P<0.05,P<0.01).CONCLUSIONS DPSCs can repair hypoxic injury to PMVECs,and the anti-oxidative stress capacity of DPSCs plays an important role in hypoxic injury repair of PMVECs.

Objective:To study the protective effect of Mongolian medicine Bateri-7 on radiation-induced intestinal injury in mice.Methods:C57BL/6J male mice were randomly divided into control group, irradiation group and irradiation plus drug administration group, with 10 or 15 mice in each group. For irradiation group, the mice were given a single dose of 12 Gy 60Co γ-rays with total body irradiation. For drug treatment, the mice were gavaged with Bateri-7 (530 mg/kg) 7 d before irradiation until 3 d after IR. At 6 h and 24 h after irradiation, the Tunel positive cells in intestine were detected immunohistochemically. At 3.5 d after irradiation, the structure of intestinal villi was observed by HE staining, and the BrdU and Ki67 positive cells were detected immunohistochemically. The expression levels of IL-6, TNF-α and Cxcl-5 were detected by qPCR. The FITC-dextran in peripheral blood was also determined. Results:The survival of irradiated mice was significantly increased by Bateri-7 ( χ2= 5.84, P < 0.05), but there was no significant difference in weight between two groups ( P > 0.05). The villi length of small intestine in the irradiation plus drug group was significantly longer than that in the irradiation group ( t = 20.24, P < 0.05), and there was no significant difference in the depth of intestinal crypt between two groups ( P > 0.05). At 6 and 24 h after irradiation, the number of Tunel positive cells in intestinal crypts in the irradiation plus drug group was significantly reduced in comparison with the irradiation group ( t = 3.52, 2.90, P < 0.05). At 3.5 d after irradiation, the level of FITC-dextran in serum and the expressions of IL-6, TNF-α and Cxcl-5 in small intestine of mice in the irradiation plus drug group were significantly lower than those in the irradiation group, respectively( t = 6.92, 7.01, 7.18, 13.16, P < 0.05). The number of BrdU and Ki67 positive cells in the crypt of mice in the irradiation plus drug group was higher than that of the irradiation group ( t = 3.91, 2.57, P < 0.05). Conclusions:Mongolian medicine Bateri-7 can effectively alleviate irradiation-induced intestinal injury of mice, which may have a good preventive and therapeutic effect on radiation enteritis.

Objective To understand the radiation protection effect of pre-irradiation administrations of nilestriol on the mice with bone marrow type of acute radiation syndrome after irradiation with 60Co γ-rays,along with its mechanisms for improvement of hematopoiesis.Methods The nilestriol administration protocols were prepared by analysis of peripheral blood cell counts and survival rate experiment on mice.The mechanisms by which the pre-irradiation twice administrations improved the post-irradiation recovery of bone marrow hematopoiesis were studied by the analysis of the surface marker of bone marrow hematopoietic stem/progenitor cells of mice and by the inspection of hematopoietic progenitor cell colony and by using histopathological assessment of bone marrow.Results Pre-irradiation administration of nilestriol at two-or three-day intervals had been shown to increase survival rates up to 100％ in mice exposed to 9.0 Gy γ-rays,which was superior to a single administration (20％,x2 =21.66,21.66,P ＜0.05).The pre-irradiation administration both at one-day or two-day intervals were capable of improving the recovery of peripheral blood counts,including white blood cell (WBC),red blood cell (RBC),and platelet in mice exposed to 6.5 Gy (F =21.33,100.9,49.34,19.19,P ＜ 0.05),showing the better effects than a single administration (F =17.11,63.38,21.89,14.37,P ＜ 0.05).The two-day-interval administration of nilestriol could significantly increase the numbers of bone marrow hematopoietic stem/progenitor cell counts (t =8.58,2.80,P ＜ 0.05) in mice on day 10 after 6.5 Gy irradiation.This also could be capable to significantly improve colony formation,with there being statistical difference compared with single administration(t =4.29,6.34,P ＜ 0.05).Also the administration at two-day-interval were also usefull in reconstruction of hematopoietic cell hyperplasia of bone marrow of irradiated mice.Conclusions As compared with conventional single admination,the pre-irradiation multiple administrations of nilestriol showed significantly improved radiation protection effects.Considering a nuclear medical emergency rescue,it is recommended to follow the pre-irradiation administration of nilestriol at two-day interval,which could obtain the best protection effects at minimum administration frequency.

Objective To evaluate the effect of rhIL-11 on radiation injury to the intestinal epithelium and cells cycle of intestinal epithelial cell in mice irradiated with 3.5 Gy neutron. Methods The morphology of the small intestinal epithelium, crypt cells necrosis, and cell proliferation were observed of the epithelial cells of the irradiated mice. Cell cycle of the epithelial cells of the small intestine of the mice was examined by flow cytometry. Results rhIL-11 pretreatment before and treatment after irradiation could accelerate the repair of small intestinal mucosa in irradiated mice. G 2/M block which occurred in the irradiated small intestinal epithelial cells and the rhIL-11 treatment might significantly increased the proportion of cells at S phase. Conclusion rhIL-11 could significantly exert a preventive effect on the small intestine against radiation injury in neutron irradiated mice, with an impact on cell cycle of the intestinal epithelial cells.