The Healing Effect Of Heparin On The Traumatic Tympanic Membrane Perforation In Rats

Background: The traumatic tympanic membrane (TM) perforation is a common condition that most patients can be self-healing. But the healing time is uncertain and hearing loss or tinnitus can brought about psychological stress to patients during healing, once secondary infection can lead to permanent tympanic membrane perforation. These issues warrant investigation into non-surgical alternatives to conservative treatment. In recent years ,studies have focused on the materials that combined with atelocollagen membrane closing traumatic TM perforation . Heparin as an anticoagulant to enter the clinical more than 80 years ago, Recently, more and more biological activity of heparin was found, and its role in normal wound healing is well documented. The ability of heparin to promote healing of tympanic membrane perforations has rarely been shown in studies.Objective: To develop an animal model of traumatic TM perforation in the rat and to access the efficacy of heparin in the treatment of acute perforations in the animal model.Methods:①To develop an animal model of traumatic TM perforation in the rat:40 rats (200-300g) were used, All animals were anesthetized with Pentobarbital sodium (0.3ml/100g), then bilateral central perforations were created by excising (2㎜╳2㎜) of the tympanic membrane with a thermal needle. To discourage infection,intramuscular injections of ampicillin sodium (150 mg/kg) were given after the operation everyday for a total of five days.②40 rats were randomly divided into two groups: In the first group,right ear was treated by using heparin combined with Gelfoam pledget which was placed over the TM perforation in contact with both the TM remnant and medial ear canal wall,and left ear served as blank control.In the second group,the right ear was treated by using heparin combined with Gelfoam pledget,left ear was treated by using EGF combined with Gelfoam pledget. 5 rats were killed after 3,5,7,10 days in each group , then the temporal bones of every animals were fixed in 10%formalin, sectioned at 4μm,stained with hematoxylin-eosin and examined by immunohistochemical method using polyclonal antibodies of EGF. Immunohistochemical data were analyzed with Paired-Sample T Test.Results:1.one animal was lost because of anesthetization. 2 ears were included in the analysis.because of otitis media.2.In the healing TM using heparin combined with Gelfoam pledget , the wounded area was covered completely by outer squamous epithelium after 3 days, the fibrous lamina and lining flat epithelium of ear drum were regenerated. Histology of heparin -healed TM at 5 days is very similar to that of normal,both in their overall thickness and in the relative proportions of the three component layers.3. Statistical difference between treated and control ears in the expression of EGF was evident(p<0.05) on different times. Statistical difference between heparin and EGF ears in the expression of EGF was evident(p<0.05) on 3,5,7days .Conclusions:1. Heparin can enhance the expression of EGF in the healing TM perforation .2. These results suggest heparin is effective in enhancing closure of traumatic TM perforation and can shorten the healing time of TM in the rat model. Histology of heparin -healed TM is very similar to that of normal,both in their overall thickness and in the relative proportions of the three component layers.