Construction Of A Rabbit Ear Model Of Refractory Wounds Using Transfixion Ligation Combined Burn Methord

Objective:To establish a refractory wounds model for ischemia and congestion usingrabbit ears.Methods:（1）Eight New Zealand white rabbits were selected to pass the full—layerskin and cartilage of rabbit ears and to ligate all blood vessels except for thosefrom eaudate．The location of suture was exposed and sterilized by iodophorsthree times a day．The changes of temperature and color，as well as dropsy andinfection of suture part were observed，and the vein blood gas analysis for theears was performed on day1，7，14，21after ligation．（2）Atotal of12rabbits were divided into six groups. The djusting pressureand temperature and autocontrol scalding instrument was utilized as thescalding equipment.Two wounded areas，with the diameter of1cm，werecreated in middle area of the back of each rabbit ear symmetrically. Thescalding time lasted0.6,0.8，1.0,1.2，1.5and2.0seconds. The change of woundappearance and the hismpathlogical examination of the injured tissue were observed24hours after scald.（3）A total of30rabbits were divided into six groups:the punch merelygroup(group A)、 the suture ligature and punch group(group B)、 the burnmerely group(remove dead skin after24h,group C)、 the burn merelygroup(remove dead skin after48h,group D)the suture ligature and burn group（remove dead skin after24h，group E）、 the suture ligature and burn group（remove dead skin after48h，group F). The wounds were sterilized with0.5%iodophors three times a day. The change of wounds from rabbit ears and the timeof wounds healing were observed, and hematoxylin-eosin staining and basicfibroblast growth factor (bFGF).Immunohistochemical staining were made at7th,14th and21st day after punching and burning operation to observegranulation tissue growth, epidermidalization extent and bFGF expressionconditions of granulation tissue.Results:（1）The color turned tO deep violet—black immediately after stitch andlighter14days later still somewhat violet—black till21days．Dropsy appearedon the first day and was very obvious on the seventh day after ligation，thereafter the degree of dropsy gradually decreased and dropsy was notnoticeable on21Stday after ligation． The parameters we detected suchastemperature，oxygen partial pressure and carbon dioxide partial pressure ofvein blood were lower after ligation than before ligation.(P<0.01)(2) The wounds were round and clear．The scalding time tor0.6（0.8），1.0，1.2，1.5（2.0）seconds could result in superficial second，deep second，third，fourth degree of burn respectively．The injury depth was correspondentWith scalding time．(3) The color of rabbit ears in the group E、F and B showed immediately deep violet-black after ligating operation and continuously showed somewhatviolet-black, violet and somewhat violet at14th,21th and28th.day.(3)The timeof wound healing were recorded respectively about10.00±1.00d、14.67±0.58d、14.33±0.62d、17.67±1.15d，19.67±0.52d and25.66±0.73d.(4) After7days ofsurgery：In D、E and F groups, wounds were covered by a few of granulationtissue，a large number of inflammatory cells were infiltrated, tissue edema isobvious. In group B,wounds were covered by a mass of granulation tissue, alarge number of inflammatory cells were infiltrated, tissue edema is lesser thangroup D、E and F. The wounds of group A have healed. After14days ofsurgery：wounds were covered by a mass of granulation tissue and a largenumber of inflammatory cells were infiltrated in group E. In group F, woundswere covered by a few of granulation tissue，a large number of inflammatorycells were infiltrated. The wounds of group C have healed.In group D, woundswere still covered by a mass of granulation tissue and the number ofinflammatory cells are more than group C. The wounds of group B havehealed.The scar tissue was observed in group A. After21days of surgery：Thewounds of group E and D have healed. A large number of inflammatory cellswere still observed in group E. In group F,wounds were still covered by a massof granulation tissue, a large number of inflammatory cells were infiltrated. Afew of inflammatory cells were infiltrated in healing wounds of group C andB.The scar tissue have formed in group A.(5)Compared with the groupA、C、E、A、B, the time of granulation tissue growth, the time of wound healing (P<0.01)and epidermidalization in the groupB、D、F、C、E were delayed and bFGFexpression were lower(P<0.01or P<0.05).Conclusions:(1)The model we established is reliable and convenient to produce，which can be used in the study on the wound repair resulting from ischemia and bloodstasis．(2)In our work，the scalding equipment is simple，the operation isconvenient and safe。the shape and size of wounds are completely same，and thedepth of wounds is accurate and steady．The presented model can be used forbum wound repair research．(3)The model of the suture ligature and burn established is reliable as anideal animal study model of non-healing wound healing for ischemia andcongestion.