| Objective:To establish an animal model of oral keratinized mucosal wound with scientificity,reproducibility,similarity,reliability,and standardization.Platelet-rich fibrin(PRF)was used as an intervention method to study the effect of platelet-rich fibrin on inflammation,re-epithelialization and the expression of collagen and TGF-beta 1 in wound healing of rabbit hard palate mucosa.Methods:Twenty-seven male Japanese white rabbits were randomly divided into PRF experimental group(A group,n=12),blank control group(B group,n=12)and normal group(C group,n=3).Keratinized mucosa wounds were generated by using a punch-biopsy instrument(diameter 10mm)at the middle third of hard palate,respectively far from bilateral mucosal margin 2.5mm,and from maxillary teeth 10mm.In group C,PRF membranes and normal mucosal tissue blocks were prepared,PRF membranes were stained with HE,and normal mucosal tissue blocks were stained with HE,VG and TGF-?1.The PRF membrane was sutured at the wound in group A,and no treatment was performed in group B.The average thickness of the mucosal tissue blocks in each group was measured,and the errors due to their different thicknesses were excluded.The gross observation and wound healing rate analysis were performed on the 3rd,7th,14th,and21th day after surgery in group A and B,respectively.Gross observation and wound healing rate analysis were performed at 3,7,14 and 21 days.After being sacrificed,HE,VG and TGF-?1 staining was performed after collected the specimen on the surgery area.And the grades of inflammation,the average thickness of epithelium,collagen fiber OD values and TGF-beta 1 OD values were statistically analyzed.Results:1.PRF membrane HE staining:The homogenous red-stained fibrin ends have a large number of nuclear blue-stained leukocytes.2.The average thickness of mucosal tissue in each group was not statistically different(P>0.05).3.Gross observation:After 3 days,the inflammation was relatively mild and PRF membrane was firmly covered on the wound surface in group A,and the wound surface was red and swollen in group B;in the 7th day after surgery,the margins of group A were not swollen,and the PRF membrane was firmly associated with the surrounding mucosa.The margin was slightly swollen in group B;14 days after the operation,both groups were covered by mucosal epithelium,and group A had a smaller area of depression than that of group B.On the 21st day after surgery,the wound depression in the two groups continued to shrink.The wound in group A was smaller than that in group B.There was evidence of scar contracture in the wound in group B.4.Wound healing rate:There was statistical difference between grouping and time(P<0.01).A group was higher than group B at 7 days and 14 days postoperatively(P<0.01).There was no statistical difference between group A and group B(P>0.05)on postoperative days 3 and 21.5.HE staining results:3 days after the operation,both groups were basically necrotic tissue.Infiltration of inflammatory cells in group A was less than in group B;7days after operation,PRF membrane induced neo-epithelium in group A.Group B was partly necrotic tissue.The infiltration of inflammatory cells was obvious.And granulation tissue appeared in both groups.On the 14th and 21st days after operation,both groups showed a complete epithelial structure,inflammation was significantly reduced,and the connective tissue under the epidermis was obvious.6.Inflammation grades:There was respectively a statistically significant difference among the groups A and group B(P<0.01).There was a statistically difference between the two groups at 3 days postoperatively(P<0.05,B>A),and there was no statistical difference at other postoperative time points.(P>0.05);The two groups were higher than the C group on the 3rd and 7th days after operation(P<0.05),while there was no statistical difference between the two groups and the C group at the 14th and 21st days of the operation and(P>0.05).7.The average epithelial thickness:There was no significant difference between group A and group C at 14 days and 21 days postoperatively(P>0.05).Group B was less than group A at 14 days(P<0.01)and group C at 14 days(P<0.05).Group B was greater than Group A at 21 days after surgery(P<0.01)and was not statistically different from Group C(P>0.05).8.OD values of collagen fibers:There was statistical difference between grouping and time(P<0.01).Group A was statistically different from group B at 7 days,14 days and 21 days after operation(P<0.01 for 7 days,A>B;P<0.01 for 14 days,A>B;P<0.01for 21 days,A<B).There was no difference between group A and group B at 3 days after surgery(P>0.05).A group and B group were larger than group C at 21 days after surgery(P_A<0.05,P_B<0.01),but numerically,group A was closer to group C.Group A peaked at14 days after surgery,and group B peaked at 21 days after surgery.9.OD values of TGF-?1:There was statistical difference between grouping and time(P<0.01).The differences between group A and group B were statistically significant at days 3,7,and 21 after surgery(P<0.01 for 3 days,A<B;P<0.05 for 7 days,A>B P<0.01 for 21 days,A<B).There was no significant difference between group A and group B at days 14 days after surgery(P>0.05).A group and B group were larger than group C at 21 days after surgery(P_A<0.05,P_B<0.01),but numerically,group A was closer to group C.Both groups peaked at 3 days postoperatively.Conclusion:1.Successfully established an animal model of oral keratinized mucosal wounds,which laid the foundation for the follow-up study of methods,materials,and mechanisms for promoting keratinized mucosal wounds repair.2.PRF may promote the healing of keratinized mucosal wounds through early regulation of inflammatory response,guiding keratinized mucosal epithelium regeneration,the early increase of collagen fiber synthesis.3.PRF may regulate inflammatory reaction and scar contracture by down-regulating TGF-?1 expression and up-regulate TGF-?1 expression to promote collagen deposition and angiogenesis. |
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