| Background and ObjectiveAs the development of social and the population ages, acute and chronic woundshave become more frequent and prevalent. Acute trauma, such as traffic accident ornatural disasters, often leads to skin soft tissue defects, tendon and (or) bone exposure.The repair work of these wounds is considered to be complex, and it is one of thechallenge for surgeons. The conventional treatment method used for these uncovered,open wounds is skin grafting or flap surgery after the formation of healthy granulationtissue by wound preparation. Wet dressings were always used to prepare the wound bed toimprove the acceptance of skin grafts. However, the simple wet dressing always prolongedthe duration of treatment and is difficult to form healthy granulation tissue. Adequategranulation tissue is conducive to the success of skin graft or flap surgery.Negative pressure wound therapy (NPWT), also known as vacuum-assisted closure(VAC)， is a new wound care method rising in recent years and widely used. The conceptof NPWT is using the medical poly foam dressing and semi-permeable film to coverer the wound, and then connecting the wound dressings to the negative pressure source by adrainage tube. Research suggests that NPWT increase wound blood flow, promote thegrowth of granulation tissue, reduce bacterial colonization and proliferation, and maintaina moist wound environment. Despite the widespread use of NPWT, little is known aboutthe mechanisms of action at the molecular level, and especially about of the mechanismsthat regulate neovascularization in the treated wounds. With the present study, we aimed atidentifying the functional and anatomical characteristics of newly formed vessels as wellas to investigate angiogenic factors expression profiles under the effect of differenttreatment patterns of NPWT.Methods1. Forty male SD rats were randomly divided into two groups, treatment group andcontrol group. A2cm×2cm full-thickness wounds were created on the dorsa of rats.The wound on the control group were covered with conventional dressing, thetreatment group wounds were covered with medical foam dressing and subjected tonegative120mmHg of continuous pressure (4hours/day) for7days.Wound perfusionwas measured by laser duplets1st,3rd,7thday post-surgery. Vasculature in the woundswas assessed by staining for CD34and H＆E staining at3rdand7thday post surgery.The factor expression of wound tissue was detected by PCR at1st,3rd,7thday postsurgery.2.2Sixty male SD rats the rats were randomized into two groups, the diabetic group (n=30) and control group (n=30). Diabetes was induced by intra-peritoneal injection ofstreptozotocin. After48h, blood glucose levels were assessed, and monitored eachweek till3weeks later; rats were included in the study if glucose concentrationswere>16.7mmol/L in heparinized tail vein blood. Two weeks later, full-thicknesswounds were created on the dorsa of rats. All of the wound were covered withconventional dressing. The rat of wound healing was compared at1stday,3rdday,7thdayand14thday. The wound perfusions were measured at indicated time(post-surgery1stday,3rdday,7thday).3. Sixty diabetic rats induced by streptozotocin were randomly divided into two groups, treatment group and control group. Full-thickness wounds were created on the dorsaof rats. The wound on the control group were covered with conventional dressing, thetreatment group wounds were covered with medical foam dressing and subjected tonegative120mmHg of continuous pressure (4hours/day) for7days. Wound perfusionwas measured by laser duple at1st,3rd,7th day post-surgery. Vasculature in thewounds was assessed by staining for CD34and HE staining at3rdand7thdaypost-surgery. The factor expression of wound tissue was detected by PCR at1st,3rd,7thand14thday post-surgery.Result1. Compared to the control group, NPWT significantly increased the wound perfusion atindicated times (post-surgery1st,3rd,7thday)（P＜0.05）. Wound vessel density washigher than control group at3rdday post-surgery. At7thday post-surgery, theneovascularof treatment group wound was arranged regular and with lager lumen,while the neovascular of control group was arranged disorderly and with tortuouslumen. The expression of VEGF and Ang1were both up regulated at3rddaypost-surgery（P＜0.05）.2. Compared with normal rats, diabetic rats showed polydipsia, polyuria and polyphagiasymptoms. Fur yellow, slow weight gain. The rate of wound healing at indicated timepoints (3rd,7thand14thdays post-surgery) was significantly lower than in normal rats（P＜0.05）. The wound perfusion was significantly lower in diabetic group comparedto than normal group（P＜0.05）.3. Compared to the control group, wound perfusion of treatment group were higher atindicated time point. At the3rd day post-surgery, wounds vascular density of thetreatment group was significantly higher than that in the control group（P＜0.05）.However, wound vascular density was no significant difference between the twogroups at the seventh day, but Histopathology showed the new blood vessels intreatment group were arranged regular and with the lager and patency lumen. At the7thand14thday, the expression of Ang2in the treatment group was significantly lowerthan the control group（P＜0.05）. Conclusion1. NPWT may increase wound blood flow perfusion of the normal rats, and is beneficialfor the angiogenesis. Its mechanism may be related to the up-regulation of expressionof angiogenic factors VEGF and Ang1.2. Blood supply of diabetic rats wound was poor. The wound angiogenesis dysfunctionmay be one of the reasons for its impaired wound healing.3. NPWT can improve diabetic wound blood perfusion and increase micro vessel density.It is helpful for new blood vessels mature. The impact on the Angs/TIE-2pathwaymay be its one of the possible mechanisms. |
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