| Objectives: To investigate the effect and mechanism of the role of basic fibroblastgrowth factor combined with bone mesenchymal stem cells in promoting healing ofβ-rayirradiated skin injury.Methods:1.3SD rats （age:6-8weeks old）, clean grade, were killed using cervical dislocationmethod. We obtained the femur and tibia bone marrow under sterile conditions, isolatedand cultured bone mesenchymal stem cells （BMSCs） by density gradient centrifugationand adherent culture. These cells were labeled by DiI when the passage grown into passage3, 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×30mm） in rats, andestablished acute deep Ⅱ β-irradiated skin injury model of rats. Those60SD female ratswere randomly divided into3groups: bFGF+BMSCs （Group A）, BMSCs （Group B）,normal saline control （Group C）. In Group A, n=20,1ml BMSCs suspension (1*106/ml inconcentration) were injected subcutaneously after the wound appeared, and bFGF wassprayed to the wound regularly; In Group B, n=20, BMSCs was merely injected when thewound appeared, with the same method as the group A. In Group C, n=20, the control rats,normal saline was injected when the wound appeared with the same method as the group A.We observed the wound healing every week, and excised the wound tissue by5mm*5mmin size under sterile conditions in the1st,3rd, and5th week after the treatment. Thesamples were examined with light microscopy, and immunohistochemistry stained withbFGF and VEGF antibodies.Results:1. Growth and observation of BMSCs: After24hours of primary cultures, there weremany cells adhering on the wall of the culture dishes, and the culture entered into theexponential growth phase6-8days later. After3times of subculture, we labeled theBMSCs cells with DiI and checked them with fluorescence microscope, red fluorescence was found. After injecting these cells into the wound, red fluorescence still could bedetected with fluorescence 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:31.63±2.31days in group A.38.81±2.80days in group B.45.62±3.95days in group C. Compared with the group B andC, the time of wound healing in group A was significantly short （P<0.05）. The time ofwound healing in group B was significantly shorter than that of Group C （P<0.05）.②Light microscope: the epidermal cells, vascular endothelial cells, and fibroblasts in GroupA were significantly more than the cells in group B and C. These cells in group B weresignificantly more than in group C.③Immunohistochemistry showed that: bFGF,VEGF-optical density value of the group A in the1st,3rd, and5th week after BMSCs suspensioninjection combined with bFGF was significantly more than that of group B and C（P<0.05）, these factors of group B were significantly more than that of group C（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. BMSCs growth was stable in vitro, remained undifferentiated state after subculture.DiI labeled BMSCs were stable and reliable, which can be used in BMSCs tracing study.3. bFGF combined with BMSCs can promote the healing of β-ray skin injuryirradiated, and reduce wound healing time.4. bFGF combined with BMSCs can promote the healing of β-ray irradiated skininjury. The mechanism is that bFGF can induce the differentiation of BMSCs into thevessel endothelium cells, epidermal cells and fibroblasts，and increase the number ofrepaired cells in local wound. BMSCs can promote the secretion of bFGF and VEGF, andalso have a synergistic effect between bFGF and BMSCs, and hence promote the repair ofwounded skin. |
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