Functional Recovery Of Radiation-induced Damaged Salivary Gland With Hypoxia Preconditioning Human Amniotic Mesenchymal Stem Cells

Objective:To investigate Functional Recovery of Radiation-induced Damaged Salivary Gland with Hypoxia Preconditioning Human Amniotic Mesenchymal Stem Cells.Methods:(1)HAMSCs was isolated from human amniotic tissue by mechanical method and enzyme digestion method.The characteristics of stem cells were identified by immunocytochemical staining,differentiation of cells into lipid and osteogenic differentiation,and identification of cell immunophenotype.The cells were pretreated with hypoxia and normoxic 48h to prepare for animal experiments;(2)Six normal female mice and 18 female mice were treated with a single-use 15Gy electron beam to perform local head and neck irradiation to make salivary gland injury models,divided into 4 groups:control group,irradiation+PBS group(IR+PBS),and irradiation.+Normoxic treatment of human amnioticmesenchymalstemcell group[IR+Nor-hAMSCs(IR+Nor)],irradiation+hypoxic preconditioning of human amniotic mesenchymal stem cell group[IR+HP-hAMSCs(IR+HP)];(3)The concentration of the injected cells was adjusted to1×10~6/ml and the injection dose was 20μl.The mice were orthotopically transplanted into the submandibular gland,and the indexes were measured 2 months of the cell therapy;(4)Check indicators:After determining the body weight,salivary flow rate,and lag time of each group of mice,the mice were sacrificed and the submandibular glands were weighed for HE staining,TUNEL tissue apoptosis detection,andα-Amy immunohistochemistry for all data.analysis.Results:(1)The body weight of mice decreased after radiation injury alone,and then gradually recovered to the level before radiation injury.The salivary flow of mice after radiation injury was smaller than that of normal mice.Submandibular gland tissue HE staining showed that a large number of acinar tissues in the submandibular gland of mice disappeared,the structure of the tissue was disordered,and interstitial fibrosis occurred;(2)After 2 months of cell therapy,the salivary flow and gland weights of IR+Hor group and IR+Nor group were significantly better than that of IR+PBS group,but were less than that of control group(P<0.05).IR+HP group had more than IR+Nor group.A small increase(P<0.05);IR+PBS group lag time is longer than the control group(P<0.05),IR+Nor group and IR+HP group lag time is roughly the same,but still longer than the control group,the differences between the groups No statistical significance(P>0.05);(3)After 2months of cell therapy HE staining:The number of acinar cells in the IR+PBS group was greatly reduced,the remaining acinar cells were vacuolized,the mechanism changed dramatically,and the interstitial fibers appeared to be changed.In the IR+Nor group,compared with the IR+PBS group,the number of acinar cells increased,serous acini showed mild edema,and interstitial fibrosis decreased.Compared with IR+PBS group,IR+HP group significantly increased the number of acinar cells,and the cell structure was similar to normal cells;(4)The cell apoptosis rate after 2 months of cell therapy was higher in IR+PBS group than IR+HP group and IR+Nor group(P<0.05),IR+HP group was lower than IR+Nor group(P<0.05);(5)Immunohistochemical staining:α-Amy was expressed in all groups,IR+HP group and IR+Nor group were increased compared with IR+PBS group(P<0.05),and IR+HP group was more expression than IR+Nor group.(P<0.05).Conclusion:Hypoxic preconditioning of human amniotic mesenchymal stem cells was more effective than normoxic culture in the repair of radiation-damaged parotid glands.