| Objectives: To investigate the effect and mechanism of the role of epidermal growthfactor combined with bone marrow mesenchymal stem cells in promoting healing ofβ-ray irradiated skin inyury.Methods:1.3SD rats(6-8weeks old),clean grade, were killed using cervical dislocation method.We obtained the femur and tibia bone marrow under sterile conditions, isolated andcultured bone mesenchemal stem cells(BMSCs) by DiI when the passage grow intopassage3,and then we prepared the BMSCs suspension(1×106/ml in concentration).2.60female SD rats (age:3-months old),clean grade. We applied single dosage(45Gy)of β-ray irradiation by linear accelerator on buttock skin (40mm×40mm) in rats, andestablished acute deep II β-irradiated skin injury model of rats. Those60SD female ratswere randomly divided into4groups: EGF+BMSCs (Group A), EGF((Group B),BMSCs((Group C),normal saline control(Group D).In Group A,N=20,1ml BMSCssuspension(1×106/ml in concentration) were injected subcutaneously after the woundappeared, and EGF were sprayed to the wound regularly; In Group B, n=20, EGF wasmerely sprayed to the wound regularly, with the same method as the Group A; In GroupC,n=20, BMSCs was merely injected when the wound appeared, with the same methodas the Group A; In Group D, n=20,the control rats,normal saline was injected when thewound appeared with the same method as the Group A. We observed the wound healingevery week, and excised the wound tissue by5mm×5mm in size under sterile conditions inthe1st,3,and5th week after the treatment. The samples were examined with lightmicroscopy, and immunohistochemistry stained with EGF,TGF,PDGF,NGF antibodies. Results:1.Growth and observation of BMSCs: After24hours of primary cultures, there weremany cells adhering in the wall of the culture dishes, and the culture entered into theexponential growth phase6-8days later. After3times of subculture, we labeled the BMSCscells with DiI and checked them with fluorescence microscope, red fluorescence was found.After injecting these cells into the wound, red fluorescence still could be detected withfluorescence microscope.2. Wound observation: hair began to fall in2weeks after irradiation, redness appearedlocally on the skin, and blisters were formed in3weeks after irradiation, the woundappeared and then gradually increased in4weeks after irradiation, and the wound becamestable5weeks after irradiation.①Wound healing time: in group A. in group B. in group C.in group D.②Light microscope: the epidermal cells, vascular endothelial cells, andfibroblasts in group A were significantly more than the cells in group B、C and D. Thesecells in group B、C were significantly morethan in group D.③Immunohistochemistryshowed that: EGF,TGF,PDGF,NGF-optical density value of the group A in the1st,3rd,and5th week after BMSCs suspension injection combined with EGF was significantly morethan that of group B、C and D(P＜0,05)，these factors of group B、C were significantlymore than that of group D(P＜0,05).Conclusions:1. Application of β-ray linear accelerator in establishing animal model of skin damageis simple. The dose is accurate and reliable.2.EGF combined with BMSCs can promote the healing of β-ray skin injury irradiated,and reduce wound healing time.3.EGF combined with BMSCs can promote the healing of β-ray irradiated skininjury. The mechanism is that EGF can induce the differentiation of BMSCs into theepithelial cells, fibroblasts, vascular endothelial cells, and can enhance the viability ofepithelial cells and other tissue repair cells, increase the number of repair cells in localwound，regulate collagen metabolism and related enzyme，regulate the informationpathways of cell cycles and apoptosis, synergistic effect between EGF and BMSCs, andcan enhance the healing of β-ray irradiated skin injury. |
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