| At present,the skin soft tissue expansion is widely used in plastic surgery.With inserting the expander and injecting water in it regularly,expanded skin can produce additional skin that is similar to the adjacent tissue's color for repair of tissue defect.However,there are still many problems on tissue expansion,such as long expansion cycle,low growth rate of tissues,and over-rapid expansion,which lead to disordered blood supply and higher immediate stretch-back rate.Additionaly,the extreme length and width ratio of skin flap often fail to meet the repairing requirements.So how to ensure the safety and efficiency of the skin expansion has attracted increasingly attentions and become significant research focus.The first part of our experiment used rat back skin expansion model,comparing the differences of the rate of skin expansion,the blood supply and the immediate stretch-back rate of expanded skin between the botulinum toxin A(BTX-A)group and control group.Through measuring the thickness of each layer of the skin,combined with Masson staining,?-SMA,CD34 immunohistochemical staining to observethe differences between two groups on the rate of skin expansion,immediate stretch-back rate and safety.Then find out a safe and effective way to accelerate skin expansion.In the second part of this article,we used the method of the first part to expand the skin to form a expansion flap(expanded random skin flap,ERSF)of certain length and width ratio,and observed the blood supply and survival rate of skin flap after 7 days.Based on the above results,we assessed the safety and reliability of expanded skin under the intervention of BTX-A for wound repair.Part 1 The effect of BTX-A on the rate of skin expansion in rat back skin expansion model Objective:To observe the effect of BTX-A on the rate of skin expansion,blood supply,immediate stretch-back rate and histology in rats with BTX-A intervention.Methods:Eighteen Sprague-Dawley rats were randomly divided into experimental group and control group.The size of the expander was intended to be embedded in the back of the rat and intradermally injected with BTX-A or saline.Water injection was started on 1week after surgery with the frequency of twice a week,The expanders were inflated to reach the intraexpander pressure of 8Kpa every time.The expansion volume,skin blood supply and tattoo area were recorded regularly.The thickness of epidermis,dermis and fibrous capsule were observed by HE staining.Masson staining was used to observe the deposition of fibrin collagen.?-SMA immunohistochemical staining was used to evaluate the content of myofibroblasts in fibrous capsule.CD34 immunohistochemical staining was used under an optical microscope to observe the diameter and density of blood vessels in the expanded skin.The images were measured with Image Pro Plus and Image J software.SPSS 13.0 software was used for statistical analysis.Results:From the first injection to the end of expansion,compared with the control group,BTX-A group had greater volume of expansion,larger tattoo area and better blood supply of expanded skin.There were thinner fibrous capsule,lower immediate stretch-back rate,fewer myofibroblasts,larger blood vessel diameter and density in the fibrous capsule of the BTX-A group.In BTX-A group,the collagen fibers in the fibrous capsule were sparse and arranged in disorder.In the control group,the collagen fibers in the fibrous capsulewere arranged densely and regularly.There was no significant difference between the two groups in the thickness of the epidermis and dermis.Conclusion: BTX-A can increase the volume of skin expansion,improve the rate of skin expansion and reduce the immediate stretch-back rate of the expanded skin,which may be related to its inhibition of fibrous capsule,reduction of collagen deposition in the fibrous capsule and transformation of myofibroblast.BTX-A has a protective effect on the blood supply of the skin during expansion,which may be related to the effect of BTX-A on dilation of blood vessels in the skin and promotion of angiogenesis.Part2 The effect of BTX-A on the blood supply and survival rate of expanded random flaps Objective: Using the method of the first part to expand the back skin of rats,we formed a certain length and width ratio of the expansion flap,then transfered and sutured it,and observed the blood circulation and survival rate of the skin flap.Compare the difference of flap survival rate of BTX-A intervention group and control group.Methods: Dissected the back skin of rat,and lift the skin from the shallow surface of the muscle.Observed vascular distribution in rat's back skin,and provided anatomical support for the formation of ERSF.We expanded the rat's back skin as described in Part 1 for 4weeks,and the expanded skin was formed a random flap which pedicle was on the caudal side.Use the Full-Field Laser Perfusion Imager to test the blood supply and take a photo to observe the survival situation of the ERSF.7 days after surgery,we ues the software Image J to measure the survival rate of ERSF,and take the terminal of ERSF as HE stain to observe the infiltration of inflammatory cell and tissue necrosis.Results: Compared with the control group,the BTX-A group showed better results of skin flap blood supply and flap survival rate from postoperation immediately to the postoperation day 7.HE stain showed that skin flap necrosis is mainly in epidermis with less swelling,the morphological characteristics of skin is clear and the infiltration of inflammatory cell is less.While the control group presented evidently swelling,and the morphological characteristics of skin is disordered,and with large number of inflammatory cells infiltrating.Conclusion: BTX-A can improve the blood supply and survival rate of the ERSF after flap transposition. |
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