S100 calcium-binding protein A9 promotes skin regeneration through toll-like receptor 4 during tissue expansion

Background:In plastic surgery,tissue expansion is widely used for repairing skin defects.However,low expansion efficiency and skin rupture caused by thin,expanded skin remain significant challenges in promoting skin regeneration during expansion.S100 calcium-binding protein A9(S100A9)is essential in promoting wound healing;however,its effects on skin regeneration during tissue expansion remain unclear.The aim of the present study was to explore the role of S100A9 in skin regeneration,particularly collagen production to investigate its importance in skin regeneration during tissue expansion.Methods:The expression and distribution of S100A9 and its receptors-toll-like receptor 4(TLR-4)and receptor for advanced glycation end products were studied in expanded skin.These character-istics were investigated in skin samples of rats and patients.Moreover,the expression of S100A9 was investigated in stretched keratinocytes in vitro.The effects of S100A9 on the proliferation and migration of skin fibroblasts were also observed.TAK-242 was used to inhibit the binding of S100A9 to TLR-4;the levels of collagen I(COL I),transforming growth factor beta(TGF-β),TLR-4 and phospho-extracellular signal-related kinase 1/2(p-ERK1/2)in fibroblasts were determined.Furthermore,fibroblasts were co-cultured with stretched S100A9-knockout keratinocytes by siRNA transfection and the levels of COL I,TGF-β,TLR-4 and p-ERK1/2 in fibroblasts were investigated.Additionally,the area of expanded skin,thickness of the dermis,and synthesis of COL I,TGF-β,TLR-4 and p-ERK1/2 were analysed to determine the effects of S100A9 on expanded skin.Results:Increased expression of S100A9 and TLR-4 was associated with decreased extracellular matrix(ECM)in the expanded dermis.Furthermore,S100A9 facilitated the proliferation and migration of human skin fibroblasts as well as the expression of COL I and TGF-βin fibroblasts via the TLR-4/ERK1/2 pathway.We found that mechanical stretch-induced S100A9 expression and secretion of keratinocytes stimulated COL I,TGF-β,TLR-4 and p-ERK1/2 expression in skin fibroblasts.Recombined S100A9 protein aided expanded skin regeneration and rescued dermal thinning in rats in vivo as well as increasing ECM deposition during expansion.Conclusions:These findings demonstrate that mechanical stretch promoted expanded skin regeneration by upregulating S100A9 expression.Our study laid the foundation for clinically improving tissue expansion using S100A9.

Efficacy and safety of external tissue expansion technique in the treatment of soft tissue defects:a systematic review and meta-analysis of outcomes and complication rates

Background:Currently,various external tissue expansion devices are becoming widely used.Considering the scarcity of relevant application standards,this systematic review was performed to explore the effectiveness and safety of external tissue expansion techniques for the reconstruction of soft tissue defects.Method:A systematic review and meta-analysis on the efficacy and safety of external tissue expansion technique was conducted.A comprehensive search was performed in the following electronic databases:PubMed/Medline,Embase,Cochrane Library(Wiley Online Library),andWeb of Science.Studies reporting patients with soft tissue defects under the treatment of external tissue expansion technique were included.Results:A total of 66 studies with 22 different types of external tissue expansion devices met the inclusion criteria.We performed a descriptive analysis of different kinds of devices.A single-arm meta-analysis was performed to evaluate the efficacy and safety of the external tissue expansion technique for different aetiologies.The pooled mean wound healing time among patients with defects after fasciotomy was 10.548 days[95%confidence interval(CI)=5.796-15.299].The pooled median wound healing times of patients with defects after excisional surgery,trauma,chronic ulcers and abdominal defects were 11.218 days(95%CI=6.183-16.253),11.561 days(95%CI=7.062-16.060),15.956 days(95%CI=11.916-19.996)and 12.853 days(95%CI=9.444-16.227),respectively.The pooled wound healing rates of patients with defects after fasciotomy,excisional surgery,trauma,chronic ulcers and abdominal defects were 93.8%(95%CI=87.1-98.2%),97.2%(95%CI=92.2-99.7%),97.0%(95%CI=91.2-99.8%),99.5%(95%CI=97.6-100%),and 96.8%(95%CI=79.2-100%),respectively.We performed a subgroup analysis in patients with diabetic ulcers and open abdominal wounds.The pooled median wound healing time of patients with diabetic ulcers was 11.730 days(95%CI=10.334-13.125).The pooled median wound healing time of patients with open abdomen defects was 48.810 days(95%CI=35.557-62.063)and the pooled successful healing rate was 68.8%(95%CI=45.9-88.1%).A total of 1686 patients were included,265(15.7%)of whom experienced complications.The most common complication was dehiscence(n=53,3.14%).Conclusions:Our systematic review is the first to demonstrate the efficacy and safety of external tissue expansion in the management of soft tissue defects.However,we must interpret the meta-analysis results with caution considering the limitations of this review.Large-scale randomized controlled trials and long-term follow-up studies are still needed to confirm the effectiveness and evaluate the quality of healing.

Fine-needle aspiration for periprosthetic fluid removal after implantation of a remote internal-port tissue expander

Background:Use of internal filling ports in tissue expander–based reconstructions are advantageous because of easier self-care,lower infection rates,and fewer instances of capsule formation.The appearance of periprosthetic fluid accumulation after internal-port tissue expander implantation is a common complication that warrants treatment.In this study,we introduced a noninvasive method using fine-needle aspiration(FNA)to remove fluids accumulated after implantation of a remote internal-port tissue expander.Methods:In this study,245 patients who underwent implantation of remote internal-port tissue expanders in our hospital from July 1,2012,to July 1,2019,were included and divided into two groups.In the control group,patients underwent tissue expander implantation before July 1,2016,and large quantities of fluids were removed with surgical aspiration procedures in most cases.In the FNA group,the patients underwent implantation after July 1,2016,and large quantities of fluids were removed first with the FNA procedure.Patients’demographic data,indications for FNA application,and related complications were collected and analyzed.Results:Overall,395 expanders were placed in 245 patients.Postoperative management was similar in both groups.Fluids were managed with 23 expanders in the control group and with 31 expanders in the FNA group.There was no difference in the fluid aspiration rate between the two groups.The surgical aspiration rate was 11.1%(23/208)in the control group.The success rate of FNA was 90.3%(28/31).In the FNA group,the surgical aspiration rate was 1.6%(3/187),which was significantly lower than that in the control group.There were no significant differences in complications between the two groups.Conclusion:FNA can be used for periprosthetic fluid removal after the implantation of a remote internal-port tissue expander in most cases.This method is more convenient and safer than surgical aspiration for the postoperative management of internal-port tissue expander implantation.

Analysis of techniques and complications of soft tissue expander in the treatment of facial and neck scars

Tissue expansion is a naturally-occurring phenomenon.Human skin will stretch and expand naturally under continuous pressure,resulting in extra skin,which is the theoretical basis of expander reconstruction and repair.Tissue expansion technique is of great value in the reconstruction of various parts of the human body,especially in the treatment of facial and neck scars.The related complications are as follows:infection,hematoma,seroma,exposure,necrosis,displacement,skin flap retraction and so on.Patient selection,surgical design and technical control are all indispensable for obtaining good aesthetic results and reducing the incidence of complications.

Expanded Forehead Stepped Flaps for Delayed Three-Stage Repair of Midface Skin Lesions

Background The forehead flap is the best flap for nasal defect repair and nasal reconstruction.It is also an ideal option for repairing skin lesions in the midface(including the nasal area,inner area of the cheek,and upper lip of the perioral area).However,the traditional frontal myocutaneous flap is relatively bulky for repairing pure skin lesions.In addition,the original forehead flap is generally not sufficient to cover a large wound area.If a large forehead flap is removed,the donor site cannot be sutured in one stage.In this study,an expanded forehead stepped flap was used to overcome the shortcomings of the traditional frontal myocutaneous flap.Methods In stage one surgery,a rectangular expander(80–100 mL)was implanted on the side of the forehead.The expansion pot was built-in,and the excess expansion amount was 160–200 mL.After 4 weeks of rest,stage two operation was performed to remove the skin lesions in the midface.The pulsation point of the supratrochlear artery on one side was used as the pedicle,and the flap was designed diagonally to the upper region of the opposite side.The flap was designed according to the size and shape of the wound.The distal portion of the flap was separated in the superficial layer of the frontalis muscle,approximately 1.7 cm above the superior orbital edge,and cut into the submuscle.The flap pedicle was cut from the superficial layer of the periosteum to form a stepped flap.Then,the flap was rotated downward to repair the wound in the midface.Five weeks later,stage three of the operation which involved flap pedicle division,was performed.Results Expanded forehead stepped flaps were used in 12 cases with 6–36 months of follow-up.In all cases,the blood supply to the flaps was good,and their color,texture,and thickness matched well with those of the surrounding skin.All patients were satisfied with the outcome of the repair.Conclusion Expanded forehead stepped flaps present an ideal option for repairing wounds after large skin lesion resections in the midface since they have multiple edges from a reliable blood supply,easiness to transfer,and well-matched color,texture,and thickness to those of the surrounding skin of the face to no need for many auxiliary incisions.

Risk factors for tissue expander infection in scar reconstruction:a retrospective cohort study of 2374 consecutive cases

Background:Tissue expansion is used for scar reconstruction owing to its excellent clinical outcomes;however,the complications that emerge from tissue expansion hinder repair.Infection is considered a major complication of tissue expansion.This study aimed to analyze the perioperative risk factors for expander infection.Methods:A large,retrospective,single-institution observational study was carried out over a 10-year period.The study enrolled consecutive patients who had undergone tissue expansion for scar reconstruction.Demographics,etiological data,expander-related characteristics and postoperative infection were assessed.Univariate and multivariate logistic regression analysis were performed to identify risk factors for expander infection.In addition,we conducted a sensitivity analysis for treatment failure caused by infection as an outcome.Results:A total of 2374 expanders and 148 cases of expander infection were assessed.Treatment failure caused by infection occurred in 14 expanders.Multivariate logistic regression analysis identified that disease duration of≤1 year(odds ratio(OR),2.07;p<0.001),larger volume of expander(200–400ml vs<200 ml;OR,1.74;p=0.032;>400ml vs<200 ml;OR,1.76;p=0.049),limb location(OR,2.22;p=0.023)and hematoma evacuation(OR,2.17;p=0.049)were associated with a high likelihood of expander infection.Disease duration of≤1 year(OR,3.88;p=0.015)and hematoma evacuation(OR,10.35;p=0.001)were so related to high risk of treatment failure.Conclusions:The rate of expander infection in patients undergoing scar reconstruction was 6.2%.Disease duration of<1 year,expander volume of>200 ml,limb location and postoperative hematoma evacuation were independent risk factors for expander infection.

Pre-expanded occipito-dorsal flap reconstruction for neck burns: A novel approach

Reconstruction of the neck following a burn injury poses a significant challenge to reconstructive burn surgeons. Here, we report a case of successful application of pre-expanded occipito-dorsal flaps in the reconstruction of postburn scars and contractures in the neck. The patient was a 10-year-old boy who sustained scars and contractures secondary to a burn injury 4 years ago. "Super-thin"flaps were obtained through pre-expansion in the occipito-dorsal area and then transferred to the recipient site. This approach resulted in an esthetic satisfaction and a significant functional improvement, thereby having significant clinical implications in the reconstruction of soft tissue damage secondary to burn injuries in the neck.