Surgical interventions for vitiligo / 中华皮肤科杂志

Vitiligo is a common depigmented disease, and currently there is no specific treatment. In clinical practice, common treatments include topical or oral drugs, phototherapy and surgery. Surgical interventions mainly include tissue and cellular grafting. Tissue grafting techniques include punch/mini grafting, split-thickness skin grafting, epidermal suction blister grafting, and cellular grafting techniques include cultured and non-cultured autologous melanocyte grafting. These surgical treatments are safe and effective for patients with stable, localized vitiligo or those irresponsive to other therapies.

Preliminary effect observation on the application of micro-negative pressure in children with small-area deep partial-thickness burn / 中华烧伤杂志

Objective@#To preliminarily observe the effects of application of micro-negative pressure in children with small-area deep partial-thickness burn.@*Methods@#From January 2016 to August 2018, 64 children with small-area deep partial-thickness burn who were admitted to the Department of Burn Surgery of the First Affiliated Hospital of Naval Medical University were recruited in this prospective randomized controlled study. According to the random number table, they were divided into negative pressure group [18 boys and 14 girls, aged (3.9±1.6) years with total burn area of (5.5±2.2)% total body surface area (TBSA)] and conventional group [20 boys and 12 girls, aged (3.8±1.7) years with total burn area of (5.8±1.6)% TBSA], with 32 patients in each group. After admission, simple debridement was performed in the patients of 2 groups. After that, the children in negative pressure group were treated with micro-negative pressure with negative pressure material replaced every 3 to 5 days. Children in conventional group were treated with silver sulfadiazine cream with dressing change every other day. On post injury day (PID) 14 and 21, general wound observation was performed, the wound healing rate was calculated, the exudates from the wounds were cultured and the positive detection rate was calculated. The number of patients requiring surgical skin grafting was recorded and the rate of surgical skin grafting was calculated, and the complete wound healing time was recorded in the patients of 2 groups. Scar formation was evaluated by the Vancouver Scar Scale (VSS) in 3, 6, and 12 months after wound healing. Data were processed with chi-square test, t test, Bonferroni correction, and analysis of variance for repeated measurement.@*Results@#(1) On PID 14, all the necrotic tissue in the wounds of patients in negative pressure group was removed, with few exudates, and most of the wounds had been epithelialized; most of necrotic tissue in the wounds of patients in conventional group was removed, with more exudates and smaller wound healing area than those in negative pressure group. On PID 21, most of the wounds of patients in negative pressure group were healed, and the exudates were rare, while the wound healing area of patients in conventional group was significantly smaller than that in negative pressure group with more exudates. (2) On PID 14 and 21, the wound healing rates [(49.8±3.3)% and (95.8±2.4)%] of patients in negative pressure group were significantly higher than those in conventional group [(40.0±3.2)% and (75.3±2.5)%, t=11.899, 33.461, P<0.01]. (3) On PID 14 and 21, the positive detection rates of wound bacteria of patients in negative pressure group were significantly lower than those in conventional group (χ2=6.275, 5.741, P<0.05). (4) The rate of surgical skin grafting of patients in negative pressure group was significantly lower than that in conventional group (χ2=5.333, P<0.05). (5) The complete wound healing time of patients in negative pressure group [(23.9±2.3) d] was significantly shorter than that in conventional group [(27.9±1.8) d, t=-7.806, P<0.01]. (6) In 3, 6, and 12 months after wound healing, the VSS scores [(6.9±1.8), (5.6±1.4), (3.4±1.5) points] of patients in negative pressure group were significantly lower than those in conventional group [(9.0±1.5), (7.4±2.0), (5.7±1.6) points, t=-4.987, -4.127, -5.988, P<0.01].@*Conclusions@#In comparison with routine dressing change, the treatment of application of micro-negative pressure in children with small-area deep partial-thickness burn can significantly improve the wound healing rate and rate of surgical skin grafting, decrease the wound infection rate, shorten the wound healing time, and improve the wound healing quality.

Interpretation of Chinese Expert Consensus Report on Clinical Prevention and Treatment of Scar / 中华整形外科杂志

A Chinese localization protocol on scar prevention and management is needed, due to the ethnic differences and complicated clinical environment. Therefore, the "Chinese Expert Consensus Report on Clinical Prevention and Treatment of Scar" was released in 2017, after two-year extensive discussions, among 12 independent experts in burn/trauma, plastic surgery and dermatology. A number of recommendations were put forward to keep pace with the times, and adapt to the current clinical situation in China. This review is focused on some sections of the Expert Consensus, including the classification, assessment, prevention and treatment of scar, and related novel techniques, along with a briefly introduction of the rationales and theoretical evidences underlying the consensus.

Comparison of machine learning method and logistic regression model in prediction of acute kidney injury in severely burned patients / 中华烧伤杂志

Objective@#To build risk prediction models for acute kidney injury (AKI) in severely burned patients, and to compare the prediction performance of machine learning method and logistic regression model.@*Methods@#The clinical data of 157 severely burned patients in August 2nd Kunshan factory aluminum dust explosion accident conforming to the inclusion criteria were collected. Patients suffering AKI within 90 days after admission were enrolled in group AKI, while the others were enrolled in non-AKI group. Single factor analysis was used to choose independent factors associated with AKI, including sex, age, admission time, features of basic injuries, initial score on admission, treatment condition, and mortality on post injury days 30, 60, and 90. Data were processed with Mann-Whitney U test, chi-square test, and Fisher′s exact test. Variables with P<0.1 in single factor analysis and those with possible clinical significance were brought into the establishment of prediction model. Logistic regression and XGBoost machine learning algorithm were used to build the prediction model of AKI. The area under receiver operating characteristic curve (AUC) was calculated, and the sensitivity and specificity for optimal threshold value were also calculated for each model. Nonparametric resampling test was used to compare the significance of difference of AUC of the two models.@*Results@#(1) Eighty-nine (56.7%) patients developed AKI within 90 days from admission. Compared with 68 patients in non-AKI group, 89 patients in group AKI were older (Z=-2.203, P<0.05), with larger total burn area and full-thickness burn area (Z=-5.200, -6.297, P<0.01), worse acute physical and chronic health evaluation (APACHE) Ⅱ score, abbreviated burn severity index score, and sequential organ failure assessment (SOFA) score on admission (Z=-7.485, -4.739, -4.590, P<0.01), higher occurrence rate of sepsis (χ2=33.087, P<0.01), higher rates of accepting tracheotomy, mechanical ventilation, and continuous renal replacement therapy (χ2=12.373, 17.201, 43.763, P<0.01), larger first excision area (Z=-2.191, P<0.05), and higher mortality on post injury days 30, 60, and 90 (χ2=7.483, 37.259, 45.533, P<0.01). There were no statistically significant differences in sex, open decompression, admission time, 24-hour fluid volume after admission, 48-hour fluid volume after admission, the first 24-hour urine volume, the second 24 hour urine volume, the first excision time, and inhalation injury (χ2=0.529, 3.318, Z=-1.746, -0.016, -1.199, -1.824, -0.625, -1.747, P>0.05). The rates of deep vein catheterization of patients in the two groups were both 100%. (2) There were twenty possible prediction variables for preliminary establishment of model according to the difference results of single factor analysis and clinical significance of variables. (3) The logistic regression prediction model had three variables: APACHE Ⅱ score [odds ratio (OR)=1.36, 95% confidence interval (CI)=1.20-1.53, P<0.001], sepsis (OR=2.63, 95% CI=0.90-7.66, P>0.05), and the first 24-hour urine volume (OR=0.71, 95% CI=0.50-1.01, P>0.05). The AUC of the logistic regression prediction model was 0.875 (95% CI=0.821-0.930), with the specificity and sensitivity of optimal threshold value 84.4% and 77.7%, respectively. (4) XGBoost machine learning model had seven main predictive variables: APACHE Ⅱ score, full-thickness burn area, 24-hour fluid volume after admission, sepsis, the first 24-hour urine volume, SOFA score, and 48-hour fluid volume after admission. The AUC of machine learning model was 0.920 (95% CI=0.879-0.962), higher than that of logistic regression model (P<0.001), with the specificity and sensitivity of optimal threshold value 89.7% and 82.0%, respectively.@*Conclusions@#Sepsis and fluid resuscitation are two important predictive variables that can be intervened for AKI in severely burned patients. Machine learning method has a better performance and can provide more accurate prediction for individuals than logistic regression prediction model, and therefore has good clinical application prospect.

Experience of wound treatment on extremely severe mass burn patients involved in August 2nd Kunshan factory aluminum dust explosion accident / 中华烧伤杂志

Objective@#To explore experience of wound treatment of extremely severe mass burn patients involved in August 2nd Kunshan factory aluminum dust explosion accident.@*Methods@#On August 2nd, 2014, 98 extremely severe burn mass patients involved in August 2nd Kunshan factory aluminum dust explosion accident were admitted to 20 hospitals in China. The patients with complete medical record were enrolled in the study and divided into microskin graft group with 56 patients and Meek skin graft group with 42 patients. Split-thickness skin in area of residual skin were resected to repair wounds of patients in microskin graft group and Meek skin graft group by microskin grafting and Meek miniature skin grafting, respectively. The residual wound size on 28 days post injury and wound infection after skin grafting of patients in the two groups, and position of donor site of all patients were retrospectively analyzed. Data were processed with t test and chi-square test.@*Results@#The size of residual wound of patients in Meek skin graft group on 28 days post injury was (59±13)% total body surface area (TBSA), which was obviously smaller than that in microskin graft group [(70±14)%TBSA, t=4.379, P<0.05]. Twenty-nine patients in microskin graft group and 11 patients in Meek skin graft group suffered from obvious wound infection after skin grafting. Wounds of patients in two groups were repaired with residual skin around wound in head, trunk, groin, armpit, and uncommon donor sites of scrotum (4 patients), vola (10 patients), and toe or finger web (8 patients).@*Conclusions@#Meek skin graft is the first choice for wound repair of extremely severe burn mass patients, with faster wound healing, less wound infection. Uncommon donor sites of scrotum, vola, and toe or finger web can also be used for wound repair in case of lack of skin.

Short- and long-term outcomes of small auto- and cryopreserved allograft skin grafting in those with >60%TBSA deep burn wounds.

BACKGROUND: The shortage of autologous skin sources not only adds difficulty to the repair of extremely large-area deep burn wounds but affects the healing quality. The aim of the present study is to explore an ideal method for repairing large-areas burn wounds with low scar formation. METHODS: Between 2002 and 2014, we used grafting of small auto- and cryopreserved allo-skin to repair large-area residual burn wounds in wounds after 21 days 21 patients, and after early excision in 17 patients. The wound healing rate and quality were observed. RESULTS: The skin expansion rate was 1:9-1:16, and the mean area of wounds repaired after three weeks was 64.8±7.3%TBSA, the wound healing rate was 91.8±3.7%. The mean area of the early excision group was 65.9±9.8 TBSA, where the healing rate was 94.5±5.6%. After small auto- and cryopreserved allograft skin grafting, the epidermis of the auto-skin gradually replaced the allo-epidermis, and the allo-dermis persisted for a prolonged period. The dermal collagen fibers at the allo-skin grafting sites were well arranged. At 1-2-year follow-up, observation showed that the Vancouver Scar Scale total score was 4·304±2·363, and we did not discern significant contracture and dysfunction in the large joints of the four extremities. CONCLUSIONS: Small auto- and cryopreserved allograft skin grafting of small auto- and allo-skin not only raised the graft expansion rate but offers a stable wound healing rate. This new technique may provide an option for repair of large-area deep burn wounds.

Effects of caspase-1 inhibitor VX765 on cold-restraint stress-induced acute gastric ulcer in mice / 中华烧伤杂志

Objective@#To investigate the protective effects of caspase-1 inhibitor VX765 on gastric mucosa of mice with cold-restraint stress-induced acute gastric ulcer.@*Methods@#Twenty-four specific pathogen free male C57BL/6J mice were divided into normal control group (NC), cold restrain group (CR), VX765 pre-treatment+ cold restrain group (VCR), and rabeprazole pre-treatment+ cold restrain group (RCR) according to the random number table, with 6 mice in each group. Mice in group NC were injected intraperitoneally with solution of 10 mL/kg dimethylsulfoxide (DMSO) and phosphate buffer solution (PBS). Mice in group CR were inflicted with acute gastric ulcer induced by cold-restraint stress 30 minutes after intraperitoneal injection of solution of DMSO and PBS. Mice in groups VCR and RCR were inflicted with acute gastric ulcer as above 30 minutes after intraperitoneal injection of solution of DMSO and PBS with dose of 12.5 μmol/kg containing 10 mg VX765 and 40 mg/kg containing 20 mg rabeprazole, respectively. Four hour after cold-restraint stress, serum content of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6)was determined by enzyme-linked immunosorbent assay. Gross condition of gastric tissue was observed. Ulcer index was evaluated. Pathological change of gastric tissue was observed with HE staining. The relative expression of IL-1β, IL-18, and cleaved-caspase-1 in gastric tissue were detected by Western blotting. Mice in group NC were detected as above at the same time point. Data were processed with one-way analysis of variance and Bonferroni test.@*Results@#The serum content of TNF-α and IL-6 and the relative expression of cleaved-caspase-1, IL-1β, and IL-18 in gastric tissue of mice in group NC were significantly lower than those in group CR (with P values below 0.01). The content of the above-mentioned inflammatory indexes in serum and gastric tissue of mice in group VCR was significantly lower than that in group CR (with P values below 0.01). There were no statistically significant differences in content of the above-mentioned inflammatory indexes in serum and gastric tissue of mice between groups RCR and CR (with P values above 0.05). The content of the above-mentioned inflammatory indexes in serum and gastric tissue of mice in group VCR was significantly lower than that in group RCR (with P values below 0.01). Surface of gastric mucosa was smooth and morphology of mucosal cells was normal with clear structure of mice in group NC. Multiple hemorrhage of gastric mucosa, disorderly arrangement of mucosal cells, and large number of inflammatory cell infiltration around necrotic tissue were observed in mice of group CR. Decreased number of gastric mucosa bleeding, intact mucosal structure, and small amount of inflammatory cell infiltration around necrotic tissue were observed in mice of groups VCR and RCR. The ulcer indexes of mice in groups NC, CR, VCR, and RCR were 0, 18.7±1.1, 6.3±1.5, and 8.2±1.3, respectively. The ulcer index of mice in group NC was significantly lower than that in the other 3 groups (with P values below 0.05). The ulcer indexes of mice in groups VCR and RCR were close (P>0.05), which were significantly lower than ulcer index of mice in group CR (with P values below 0.05).@*Conclusions@#VX765 can effectively inhibit the activation of caspase-1, reduce production of inflammatory factor, and alleviate inflammatory response, which have protective effects on gastric mucosa of mice with cold-restraint stress-induced acute gastric ulcer.

Advances in preparation and clinical application of amniotic membrane graft / 中华烧伤杂志

Amniotic membrane has been used as wound dressing for more than 100 years. With the development of the preservation and preparation techniques, amniotic membrane is widely used in ophthalmology, burns, plastic surgery, dentistry, and neurosurgery. In recent years, as more and more amniotic membrane is used in chronic wounds, it will be a new treatment method for wounds. This paper is a brief review about advances in preparation and clinical application of amniotic membrane graft.

[Significance of extravascular lung water index, pulmonary vascular permeability index, and in- trathoracic blood volume index in the differential diagnosis of burn-induced pulmonary edema].

OBJECTIVE: To appraise the significance of extravascular lung water index (EVLWI), pulmonary vascular permeability index (PVPI), and intrathoracic blood volume index (ITBVI) in the differential diagnosis of the type of burn-induced pulmonary edema. METHODS: The clinical data of 38 patients, with severe burn hospitalized in our burn ICU from December 2011 to September 2014 suffering from the complication of pulmonary edema within one week post burn and treated with mechanical ventilation accompanied by pulse contour cardiac output monitoring, were retrospectively analyzed. The patients were divided into lung injury group ( L, n = 17) and hydrostatic group (H, n = 21) according to the diagnosis of pulmonary edema. EVLWI, PVPI, ITBVI, oxygenation index, and lung injury score ( LIS) were compared between two groups, and the correlations among the former four indexes and the correlations between each of the former three indexes and types of pulmonary edema were analyzed. Data were processed with t test, chi-square test, Mann-Whitney U test, Pearson correlation test, and accuracy test [receiver operating characteristic (ROC) curve]. RESULTS: There was no statistically significant difference in EVLWI between group L and group H, respectively (12.9 ± 3.1) and (12.1 ± 2.1) mL/kg, U = 159.5, P > 0.05. The PVPI and LIS of patients in group L were respectively 2.6 ± 0.5 and (2.1 ± 0.6) points, and they were significantly higher than those in group H [1.4 ± 0.3 and (1.0 ± 0.6) points, with U values respectively 4.5 and 36.5, P values below 0.01]. The ITBVI and oxygenation index of patients in group L were respectively (911 197) mL/m2 and (136 ± 69) mmHg (1 mmHg = 0.133 kPa), which were significantly lower than those in group H [(1,305 ± 168) mL/m2 and (212 ± 60) mmHg, with U values respectively 21.5 and 70.5, P values below 0.01]. In group L, there was obviously positive correlation between EVLWI and PVPI, or EVLWI and ITBVI (with r values respectively 0.553 and 0.807, P < 0.05 or P < 0.01), and there was obviously negative correlation between oxygenation index and EVLWI, or oxygenation index and PVPI (with r values respectively -0.674 and -0.817, P values below 0.01). In group H, there was obviously positive correlation between EVLWI and ITBVI (r = 0.751, P < 0.01) but no obvious correlation between EVLWI and PVPI, oxygenation index and EVLWI, or oxygenation index and PVPI (with r values respectively -0.275, 0.197, and 0:062, P values above 0.05). The total area under ROC curve of PVPI value for differentiating the type of pulmonary edema was 0.987 [with 95% confidence interval (CI) 0.962-1.013, P < 0.01], and 1.9 was the cutoff value with sensitivity of 94.1% and specificity of 95.2% . The total area under ROC curve of ITBVI value for differentiating the type of pulmonary edema was 0.940 (with 95% CI 0.860-1.020, P < 0.01), and 1,077. 5 mL/m2 was the cutoff value with sensitivity of 95.2% and specificity of 88.2%. CONCLUSIONS: EVLWI, PVPI, and ITBVI have an important significance in the differential diagnosis of the type of burn-induced pulmonary edema, and they may be helpful in the early diagnosis and management of burn-induced pulmonary edema.

A Randomized,Multi-center and Parallel Control Clinical Trial for Acidic Fibroblast Growth Factor in the Treatment of Deep Second Degree Burn / 中国药师

Objective:To evaluate the efficacy and safety of recombinant human acidic fibroblast growth factor( rh-aFGF)and re-combinant human basic fibroblast growth factor( rh-bFGF)in the treatment of deep second degree burn. Methods:A multicenter,pro-spective,randomized and double-blind clinical trial was conducted. Totally 216 cases of deep second degree burn were selected from five research centers and given appropriate antibiotics and nutritional supplement therapy. The wound of 108 cases in the observation group were rinsing with rh-aFGF(one bottle / 5cm2)according to the wound area at the time of admission followed by rh-aFGF daily spraying,3-4 press/cm2 ,6-8 times a day. The 108 patients in the control group were treated with rh-bFGF with the same regimen as the observation group. After the 30-day follow-up,the wound healing was evaluated in the two groups. Results:The complete healing time,debridement time,complete healing rate in 12 days and 15 days in the observation group were all better than those in the control group(P<0. 05). After the 7-day treatment,the level of leukocyte and seepage score of the observation group were both lower than those of the control group(P<0. 01). The moderate rate showed significant difference between the two groups(P<0. 05). Conclu-sion:rh-aFGF shows better clinical efficacy than rh-bFGF in the treatment of deep second degree burn with the similar safety.

Advances in the research of clinical features and treatment of ammonia burns / 中华烧伤杂志

Ammonia is commonly used in industry and agriculture. It is also one of the most frequently accidentally spilled chemicals. Exposure to ammonia can cause severe cutaneous burn or freezing injury, ocular injury, and inhalation injury, among them inhalation injury is the most lethal one. Although the diagnosis and treatment of ammonia burns have been improved, the long-term prognosis is not satisfactory. In this article, we reviewed the literature concerning ammonia burns, in order to summarize the clinical features and treatment of such injury.

Analgesia effect of a fixed nitrous oxide/oxygen mixture on burn dressing pain: study protocol for a randomized controlled trial.

BACKGROUND: Procedural burn pain is the most intense acute pain and most likely type of burn injury pain to be undertreated due to the physician's fear of the adverse effect of analgesia and lack of anesthetist present. At our institution, in most of the cases, local burn detersion and debridement were performed at the ward level without any analgesics. This article describes a study designed to test the analgesia effect of a fixed nitrous oxide/oxygen mixture on burn dressing pain. METHODS/DESIGN: The experiment was carried out in three centers. The patients were given a number from 1 to 240. A randomization list was produced by a statistician according to our preliminary study. Due to the severity of the pain suffered, ethically it was decided to help as many as possible, so patients given the letters A, B or C were treated using a canister with the appropriate letter containing preprepared nitrous oxide/oxygen mixture (NOOM). Those with D were given oxygen only, from an identical-looking canister labeled D. Neither patients, nor doctors, nor nurses, nor data collector knew what was in each canister, thus they were all blind. The nursing officer who implemented the intervention handed the doctors envelopes containing the patients' name and allocation of A, B, C or D. Thus, patients receiving NOOM or oxygen were in the ratio 3:1. Parameters, including pain severity, blood pressure, heart rate, digital oxygen saturation and the Chinese version of the burn specific pain anxiety scale (C-BSPAS), were taken before, during and after dressing for each group. A video and audio record was taken individually for later communication coding and outcome analysis. Rescue analgesic was recorded. DISCUSSION: Based on the findings from our previous qualitative study that physician's reluctance to order narcotic analgesia is due to its adverse effect and from our pilot experiment, this study aims to test the hypothesis that a fixed nitrous oxide/oxygen mixture will promote better burn dressing pain alleviation and outcomes. Analyses will focus on the effects of the experimental intervention on pain severity during dressing (primary outcomes); physiological parameters, C-BSPAS and acceptance of both health care professionals and patients (secondary outcomes). If this model of analgesia for burn pain management implemented by nurses proves successful, it could potentially be implemented widely in hospital and prehospital settings and improve patients' satisfaction and quality of life. TRIAL REGISTRATION: (Clinical Trials Identifier: CHICTR-TRC11001690).

Application and comparative studies on problem-based learning and lecture-based learning of clinical teaching in burn surgery / 中华医学教育探索杂志

To improve the quality of clinical teaching in burn surgery,79 students of Grade 2005 were randomly divided to problem-based learning(PBL)group and lecture-based learning(LBL) group.The teaching quality of two teaching methods were compared.The results showed that the average score,the score of teaching effectiveness appraisal targets in PBL group were sig-nificant higher than that in LBL group.This indicated that the teaching effectiveness of PBL was better than that of LBL,PBL should be applied in clinical teaching in burn surgery.

Reconstruction and transplantation of composite skin containing keratinocytes and fibroblasts / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the role of fibroblasts in reconstruction of composite skin, and evaluate the effect of composite skin on full-thickness skin defect.</p><p><b>METHODS</b>Keratinocytes and fibroblasts were seeded on the surface of acellular dermal matrix and cultivated in vitro to reconstruct the composite skin. Adherence of keratinocytes to dermal matrix was observed. Then take rate and histological construction were investigated after the composite skin was used to cover full-thickness skin defect wound in nude mice (n = 16).</p><p><b>RESULTS</b>Keratinocytes grew and proliferated to reach tho confluence on the surface of the acellular dermal matrix. Keratinocytes adhered more stablely and could not be torn down from dermal matrix in operation when few fibroblasts were seeded on the epidermal surface of the dermal matrix. After grafting, the composite skin closed the full-thickness wound in nude mouse. The total survival was achived in 10 mice (62.5%). The newly generated skin was with intact histological construction of base membrance containing laminin and type IV collagen.</p><p><b>CONCLUSION</b>Composite skin could close the full-thickness wound, and fibroblasts could improve adherence of keratinocytes to dermal matrix, which should benefit the survival of composite skin.</p>

An experimental study on the dermal substitute of spongy collagen membrane / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the practicability of a spongy collagen membrane as a dermal substitute.</p><p><b>METHODS</b>Porcine skin collagen was harvested and mixed and precipitated with chondroitin-6-sulfate, and then lyophilized for 48 hours to form sheets of highly porous membrane. The collagen membrane was embedded subcutaneously in SD rat's skin. The histological compatibility, the vascularization degree and degradation status were determined periodically by means of tissue sampling.</p><p><b>RESULTS</b>The collagen membrane possessed some degree of strength and tenacity with a structure consisting of multidinous interconnecting pores. It was easy to manipulate. Experimental subcutaneous embedding in SD rats indicated that the membrane exhibited good tissue compatibility, strong tendency to vascularization, with no evidence of acute inflammatory reaction, and slow degradation rate.</p><p><b>CONCLUSION</b>Spongy collagen membrane might be an optimal dermal substitute for wound coverage.</p>

EXPERIMENTAL STUDY ON THE PREPARATION AND TRANSPLANTATION OF COMPOSITE SKIN COMPOSED OF ACELLULAR DERMIS AND KERATINOCYTES / 解放军医学杂志

To study the method of preparing the composite skin composed of keratinocytes and acellular dermis, and to investigate the efficacy as well as its histological changes after being grafted on wounds of athymic mice. Compared with keratinocyte sheet grafting, the wounds grafted with composite skin had better healing rate, appearance and less wound contraction rate. Moreover, histological examination revealed fully differentiated epidermis, organized proliferated collagen fibres, and distinct reconstruction of epidermis-dermis junction in composite skin group, with absence of acute immuno-rejection response. As a new kind of skin substitutes, the composite skin can improve the quality of wound healing.

CONSTRUCTION AND GROWTH ABILITY STUDY OF A COMPOSITE SKIN COMPOSED OF KERATINOCYTES AND ACELLULAR DERMAL MATRIX / 解放军医学杂志

To investigate the possibility of constructing composite skin, keratinocytes were cultivated in vitro on the epidermal surface of cell free dermis prepared from pig skin.Keratinocytes grown on the dermal matrix were released at selected time points, followed by determining the proliferative capacity with cell number quantity and cell proliferation test. Cells attaching to the dermal matrix after it were seeded for 1 and 2 weeks were observed with histological section HE staining and electron microscopy scanning. Results showed that the number of keratinocytes was markedly increased with culture time. They maintained their proliferative potential after they were seeded on acellular xeno dermal matrix and reached a confluent monolayer or 3 to 6 layers at the 1st and 2nd week after seeding. The data showed that a living composite skin combined with keratinocytes and acellular dermal matrix could be successfully prepared in vitro.

BIOACTIVITY AND TRANSPLANTATION OF EGF GENE TRANSFECTED KERATINOCYTE / 解放军医学杂志

To investigate the expression of epidermal growth factor (EGF) of EGF gene transfected keratinocytes in vivo and in vitro after grafting. EGF levels in the supernatant of the culture media of EGF gene transfected keratinocytes cultured for different lengths of time and different passages were determined with ELISA method. Then, the gene transfected keratinocytes were seeded on the surface of acellular dermal matrix, After culture, the composite skin substitutes were grafted onto the full thickness wounds in nude mice. Specimens were harvested at intervals after grafting and stained for EGF with immunohistochemistry. The results showed that keratinocytes transfected with EGF gene secreted EGF, which was detected in the supernatant of the culture, for 5 passages. Immunohistochemical staining method showed that EGF was expressed in the newly generated epidermis 1～3 weeks after grafting of the composite skin substitute. The data showed that gene transfected keratinocytes could express EGF stably in vivo and in vitro , which would be of benefit to the construction of the tissue engineering skin.

RECONSTRUCTION OF A COMPOSITE SKIN SUBSTITUTE WITH COLLAGEN SPONGE AS DERMAL SCAFFOLD / 解放军医学杂志

To reconstruct a composite skin substitute composed of keratinocytes and collagen sponge as dermal scaffold. Collagen was extracted from fresh porcine skin. After being mixed with chondroitin sulfate, it was frozen and dried under vacuum to form a spongy membrane. Keratinocytes were separated from the foreskin with the routine method, and they seeded on the collagen membrane. The keratocytes which were carried by the collagen sponge were cultured, and the growth and proliferation were observed. The result showed that keratinocytes could grow and proliferate to form a confluent layer after 2～3 weeks. It indicated the the collagen sponge membrane showed no toxicity to human epidermal cells, and it could be used as a dermal scaffold in the construction of a composite skin substitute.

EXPERIMENTAL STUDY OF TRANSPLANTATION AND THE FATE OF COMPOSITE SKIN COMPRISING MIXED KERATINOCYTES SEEDED ON ACELLULAR DERMAL MATRIX / 解放军医学杂志

To investigate the fate of composite skin comprising mixed keratinocytes seeded on acellular dermal matrix (ADM) after its transplantation to the wound. Newborn BALB/c and human keratinocytes were mixed in various ratios, seeded on the surface of ADM, and cocultured. The composite skin substitute were then grafted onto the full thickness skin wounds in BALB/c mice. The fate of human keratinocytes was observed. The results showed that the composite skin substitutes could close the full thickness wounds in BALB/c mice. Human keratinocytes were mainly located in the upper layer of the epidermis, and were gradually replaced by BALB/c keratinocytes. This indicated that the mixed culture of keratinocytes of two different species on ADM could close full thickness wounds, having the advantages such as saving the donor skin and shortening the culture time in vitro .