The Effects Of Recombinant Human Granulocyte-Macrophage Colony Stimulating Factor On Wound Healing Of Gingiva

Objective: Wound healing is an important medical research subject, whichinvolves various cells, growth factors and cytokines. Granulocyte Macrophagecolony stimulating factor (GM-CSF), as a hematopoietic growth factor, in recentyears, whose topical application had been proved to facilitate acute or chronic woundhealing of skin or intestinal mucosa either in animal experiments or clinical trials.The oral cavity is a complex bacteria place, periodontal tissue trauma, especiallygingiva trauma after periodontal surgery is very common, however, the introductionof GM-CSF to periodontal field, at home or abroad, have rarely been reported. Afterrecombinant human GM-CSF（rhGM-CSF） gene was cloned and expressed, itgradually come into clinical application. So the aim of this experiment is to study theeffect of rhGM-CSF to skin wound repair cells whether is equally applicable ingingiva by histomorphology.Methods: Sixteen four-month-old male white rabbits, with the probingdepth≥2mm by periodontal probe, were randomly divided into two groups:experimental and control group. The object of each sample is to study the upper andlower incisors’ gums.2mms labial gingival had been removed by scalpel. Aftersurgery, every morning at7:30, the rabbits had their food and water. At9:00, theresidual food and water were removed, for white rabbits in experimental group, weuse medical cotton swab dampened with rhGM-CSF gel equably applied to thesurface of the wound gums, while saline instead of drugs with the same treatment tothe control group. The procedure was repeated at12:00.When it came to15:00, thewhite rabbits could have their food and water again. Finally, at16:30, the residualfood and water were removed, we topically applied the drugs again just the same as before, then we call it a day. The procedure were repeated until the animals werekilled，at meantime, observe the wound healing with naked eyes.3、7、11、15daysafter the surgery, at each point-in-time, two animal were randomly selected andsacrificed from the two groups separately. The specimens with teeth, gums and partof the bones in the operating area were harvested and treated with4%paraformaldehyde. After conventional decalcification, embedding, labial-linguallysliced, HE stain and PCNA （Proliferating Cell Nuclear Antigen）stain, the preparedslices were observed with optical microscope of OLYMPUS camera. Besides thenumber of PCNA-positive cells in the fields of400times vision were measured inthree different areas, with the mean value being recorded. Adopt the statisticalmethods of two independent sample t-test. Then according to the results of the twokinds of stain，combined with the naked eye’s observations, evaluate the effect ofrhGM-CSF to the healing of the gingival wounds.Results:Naked eye observation results: On the third day, both the experimental groupand control group, gums in the operating area demonstrated swelling, covered bywhite pseudomembranous and probing of easy bleeding, no significant differencesbetween the two groups. On the seventh day and the eleventh day, inflammatoryconditions improved, but the experimental group produced thicker granulation thanthe control group. While on the fifteenth day, inflammation in both groups basicallysubsided, and granulation tissue had formed, there were not obvious differencesbetween two groups.HE staining results: Gums of the experimental group had a more pronouncedinflammatory cell infiltration on the third day, more significant vascularization onthe seventh day, wider range of fibroblast cell proliferation on the eleventh day. Butto the fifteenth day, both groups’trauma had returned to normal, the experimentalgroup had thicker collagen fibers than the control group, but no significant differencebetween the two groups.PCNA staining results: In experimental group, epithelial cells around the surface of the wound proliferated more significantly on the third day, newbornepithelial cells at the surface of the wound proliferated more obviously on theeleventh day, while on the eleventh day and the fifteenth day, fibroblasts proliferatedmore prominently, comparing to the controls.Conclusion: rhGM-CSF can promote the infiltration of inflammatory cells,angiogenesis, epithelial cells’ and fibroblasts’ proliferation in gingiva. The effects ofrhGM-CSF to the repair cells of gingiva are consistent with those in skin tissue inwound healing. RhGM-CSF is beneficial with wound healing on gingival tissue.