Objective To investigate the influence of gender differences on NF-kB activation in livers in septic rats. Methods Total 20 female and 20 male Wistar rats were randomly divided into four groups.Tissue samples of the livers were collected to measure NF-kB activation by EMSA.The level of plasma ALT,TNF-?and estrogen were measured also. Results NF-kB activation in normal male and female rats has no significant difference (P＞0.05).After stimulated by LPS,the level of NF-kB activation and ALT,TNF-?in plasma were markedly upregulated,and the index of female group lower than that in male group (P＜0.01).The level of NF-kB activation in livers and ALT,TNF-?in plasma both in male and female have significantly negative correlation with the level of estrogen in plasma (P＜0.05 ).Conclusion There are significantly gender differences on NF-kB activation in livers in septic rats.Estrogen may decrease the injury of livers in septic rats.

OBJECTIVETo study the effects of glucocorticoid on skeletal muscle protein metabolism in burn sepsis and its possible mechanism.

METHODSThe rats were randomly divided into four groups with 15 rats in each group. Group B, 30% TBSA full-thickness burn was produced on the back and endotoxin (6 mg/kg bw) was given intraperitoneally after the injury to simulate burn sepsis. Groups C and D, glucocorticoid receptor antagonist RU38486 (10 mg/kg bw) was given by gavage 2 hours before or 2 hours after burn with endotoxin, respectively. Group A, the rats received only normal saline in same volume as endotoxin. Plasma levels of cortisol were determined with standard procedure. Extensor digitorium longus muscles (EDL) were procured from both legs 12 hours after the injury. After weighing, the proteolytic rate was determined in vitro in an incubation system with oxygen rich environment by high performance liquid chromatography. The gene expressions of ubiquitin, E(2)-14kDa and C2 in the muscles were determined by Northern blot analysis.

RESULTSThe weight of EDL was significantly lower in group B than in group A (t = 9.03, P < 0.01). Although the weight of EDL muscles was also lower in groups C and D than in group A, it was significantly higher than in group B (t = 2.26, 6.42, P < 0.05 or P < 0.01). The concentrations of plasma cortisol were markedly higher in groups B, C and D than in group A (t = 9.03 - 22.94, P < 0.01). A 58.8% (210/357) of the total and 335.5% (4.16/1.24) of myofibrillar proteolytic rate in group B was higher than in group A (t = 36.99 and t = 46.19, P < 0.01), respectively. The total and myofibrillar proteolytic rate in group D was 28.3% (161/567) and 49.6% (2.68/5.40) and in group C 18.9% (108/567) and 23.2% (1.25/5.40), which were lower than those in group B (t = 5.34 approximately 34.68, P < 0.01), respectively. Although the expressions of ubiquitin mRNA (2.4 kb), E(2)-14 kDa mRNA (1.2 kb) and C2 mRNA in groups C and D were significantly higher than in group A, all the values were lower than those in group B (t = 3.22, 11.32, P < 0.01), especially in group C.

CONCLUSIONSThe proteolytic rate of skeletal muscle, especially the myofibrillar proteolytic rate, was enhanced during burn with sepsis. Hypersecretion of glucocorticoid could upgrade the gene expression of ubiquitin system, resulting in hyperdegradation of skeletal muscle protein during burn with sepsis. Glucocorticoid receptor antagonist RU38486 could decrease the hyperdegradation of skeletal muscle during burn with sepsis.

Animals ; Burns ; metabolism ; Gene Expression Regulation ; Glucocorticoids ; physiology ; Hydrocortisone ; blood ; Male ; Mifepristone ; pharmacology ; Muscle Proteins ; metabolism ; Muscle, Skeletal ; metabolism ; Rats ; Rats, Wistar ; Sepsis ; metabolism ; Ubiquitin ; metabolism

OBJECTIVETo investigate the suitable transfection condition of human epidermal cells (hECs) with human epidermal growth factor (EGF) gene by adenovirus vector (Ad-hEGF) and its effects on the biological characteristics of hECs.

METHODShECs were isolated from deprecated human fresh prepuce tissue of circumcision by enzyme digestion method and then sub-cultured. hECs of the third passage were used in the following experiments. (1) Cells were divided into non-transfection group and 5, 20, 50, 100, 150, and 200 fold transfection groups according to the random number table (the same grouping method below), with 3 wells in each group. Cells in non-transfection group were not transfected with Ad-hEGF gene, while cells in the latter six groups were transfected with Ad-hEGF gene in multiplicities of infection (MOI) of 5, 20, 50, 100, 150, and 200 respectively. The morphology of the cells was observed with inverted phase contrast microscope, and expression of green fluorescent protein of the cells was observed with inverted fluorescence microscope at transfection hour (TH) 24, 48, and 72. (2) Another three batches of cells were collected, grouped, and treated as above, respectively. Then the transfection rate of Ad-hEGF gene was detected by flow cytometer (n=3), the mass concentration of EGF in culture supernatant of cells was detected by enzyme-linked immunosorbent assay (n=6), and the proliferation activity of cells was detected by cell counting kit 8 (CCK8) and microplate reader (n=6) at TH 24, 48, and 72, respectively. (3) Cells were collected and divided into non-transfection group and transfection group, with 6 wells in each group. Cells in non-transfection group were cultured with culture supernatant of cells without transfection, while cells in transfection group were cultured with culture supernatant of cells which were transfected with Ad-hEGF gene in the optimum MOI (50). CCK8 and microplate reader were used to measure the biological activity of EGF secreted by cells on culture day 1, 3, and 5. (4) Cells were collected and divided into non-transfection group and transfection group, with 12 wells in each group. Cells in non-transfection group were not transfected with Ad-hEGF gene, while cells in transfection group were transfected with Ad-hEGF gene in the optimum MOI (50). The expression levels of cytokeratin 14 (CK14) and CK19 of cells were measured by immunofluorescence staining at TH 24. (5) Cells were collected, grouped, and treated as in (4), with 6 wells in each group. At post scratch hour (PSH) 0 (immediately after scratch), 12, 24, and 48, the migration distance of cells was observed and measured with inverted phase contrast microscope. Data were processed with analysis of variance of factorial design, analysis of variance for repeated measurement, and LSD test.

RESULTS(1) At TH 24 and 48, morphology of cells in each transfection group and non-transfection group were similar. Compared with that in non-transfection group, the cell debris increased significantly in 200 fold transfection group at TH 72. At TH 24, 48, and 72, the expression of green fluorescent protein was not seen in cells of non-transfection group, whereas it increased in cells of transfection group over transfection time. (2) The transfection rate of Ad-hEGF gene of cells in each transfection group increased gradually over transfection time. At TH 72, the transfection rates of Ad-hEGF gene of cells in 50-200 fold transfection groups were all above 90%, while the transfection rates of Ad-hEGF gene of cells in non-transfection group, 5, and 20 fold transfection groups were (0.51±0.20)%, (62.44±6.23)%, and (75.00±5.43)% respectively, which were obviously lower than the rate in 50 fold transfection group [(93.12±2.55)%, with P values below 0.01]. The mass concentration of EGF in culture supernatant of cells in each transfection group increased gradually over transfection time. At TH 72, the mass concentration of EGF in culture supernatant of cells in 50 fold transfection group was obviously higher than that in each of the other groups (with P values below 0.01). The proliferation activity of cells in each group at TH 24 and 48 was similar (with P values above 0.05). At TH 72, the proliferation activity of cells in 200 fold transfection group was obviously lower than that in other groups (with P values below 0.05). (3) On culture day 1, the biological activity of EGF secreted by cells in two groups was similar (P>0.05). On culture day 3 and 5, the biological activity of EGF secreted by cells in transfection group were obviously higher than that in non-transfection group (with P values below 0.01). (4) At TH 24, the expression levels of CK14 and CK19 of cells in transfection group were higher than those in non-transfection group. (5) The width of scratch in two groups was nearly the same at PSH 0. At PSH 12-48, the migration distance of cells in transfection group was obviously longer than that in non-transfection group (with P values below 0.01).

CONCLUSIONSThe suitable range of MOI of hECs transfected with Ad-hEGF gene is 50-150, and 50 is the optimum. hECs transfected with Ad-hEGF gene with MOI 50 can effectively express the EGF gene and keep its good abilities of proliferation, differentiation, and migration, as well.

Adenoviridae ; Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; EGF Family of Proteins ; genetics ; metabolism ; Epidermis ; cytology ; Genetic Vectors ; Humans ; Keratins ; metabolism ; Male ; Transfection

OBJECTIVESTo observe the effect of recombinant human growth hormone on metabolism in severely burned patients.

METHODSFrom January 1999 to January 2001, 50 patients, aged 12 to 50 years, with over 30% total body surface area (TBSA) and 10% full-thickness burns, were randomized in a double-blind study. In the control group normal saline was used as a placebo (control group), while 0.3 IU/kg(-1) /d(-1) recombinant human growth hormone was given from postoperative day 1 to day 10 in the rhGH group. The excised burn wounds were closed with microautograft and allograft skin. Blood samples were collected at 6:00 am for assaying of growth hormone, blood glucose, blood insulin, anti-insulin antibody, glucagon, cortisol, serum amino acid profile, transferring, proalbumin, total protein, dielectric, and resting energy expenditure (REE) was also measured.

RESULTSThe concentration of blood GH in both groups was lower (t = 2.806, P < 0.05) than that of physiological values before surgery. However, the concentration of GH on POD 3 in the rhGH group was significantly higher than that of normal values, but a higher level was observed on POD 7 in the rhGH group than that of the control group (t = 3.142, P < 0.05). Although the concentration of anti-insulin antibody was slightly increased, there was no significant difference between the two groups. The concentration of glucagons tended to decrease with an increase in the concentration of blood glucose, and it was marked in the rhGH group. There was no significant difference between the two groups. The concentration of cortisol was higher than normal values, but no significant difference was observed between the two groups. With the administration of rhGH, the plasma concentration of amino acids was lower than that of the control group (t = 2.714, P < 0.05), and the urinary output of 3-MH in the rhGH group was lower than that of the control group (t = 2.207, P < 0.05).

CONCLUSIONSAdministration of rhGH in patients with major burn after surgery could improve their metabolic status, namely, increased lipolysis energy, accelerated protein synthesis, accelerated gluconeogenesis, reduced muscle proteolytic rate, and reduced REE expenditure. There is no effect on stress hormone. rhGH exerts a beneficial effect on metabolism in severely burned patients, but hyperglycemia is apt to occur, and water, Na(+), Cl(-) retention are suggested.

Adolescent ; Adult ; Amino Acids ; blood ; Burns ; blood ; drug therapy ; surgery ; Child ; Female ; Growth Hormone ; therapeutic use ; Human Growth Hormone ; genetics ; therapeutic use ; Humans ; Insulin ; blood ; Male ; Middle Aged ; Recombinant Proteins ; therapeutic use ; Sodium Chloride ; blood

This paper summarizes the latest progress in studies on artificial airway management in patients with inhalation injury in China, including evaluation and identification of injury degrees, practice of choosing artificial airway, management of crucial links, and new models of airway management, and makes proposals for future research.

Sepsis is a severe life-threatening syndrome characterized by an abnormal host response to infection that can rapidly evolve into septic shock and multiple organ failure. Treatment of sepsis depends on early identification and diagnosis as well as adequate and timely anti-infection and multi-organ functional support. In recent years, pancreatic stone protein has been widely studied as a new biomarker for sepsis. Existing evidence shows that compared with the commonly used inflammatory markers in clinical practice, pancreatic stone protein has higher sensitivity and specificity in the diagnosis of sepsis. It enables the early diagnosis of sepsis and assessment of the severity of septic patients to a certain extent. This article reviews the characteristics, biological functions, diagnostic features, and clinical application of pancreatic stone protein.

Objective:To explore the clinical effects of partially de-epithelized local flaps in repairing tubercular chest wall defects.Methods:A retrospective observational study was conducted. From April 2010 to February 2021, twelve patients who met the inclusion criteria were admitted to the Department of Burns and Plastic Surgery of the Eighth Medical Center of PLA General Hospital, including 9 males and 3 females with age of (42±18) years. The sizes of tubercular chest wall defects of patients were ranged from 4 cm×3 cm×2 cm to 16 cm×8 cm×5 cm, which were all repaired with partial de-epithelized local flaps. The widths of flaps were equal to the widths of the defects, and the lengths of flaps were 2 cm longer than those of the defects. In one patient, the local flap was too large to close the donor site directly by suturing, so an autologous back free medium thickness skin graft was used for repair. In other patients, the collection areas of local flaps were small, and the donor areas of flaps were directly closed. The duration of operation, intraoperative bleeding, and postoperative drainage volume and indwelling time of drainage tube were observed and recorded. In two weeks after operation, the survival, color, and texture of flaps, the presence of subcutaneous hydrops and skin ulcer, and donor site healing including wound disruption, local infection, hematoma were observed. Chest X-ray, CT scan, or nuclear magnetic resonance imaging was performed in one month after operation to check whether new local hydrops and bone destruction occurred in the chest wall defects and the concomitant tuberculose focus of patients. All patients were followed up for more than 6 months to record whether the surgical incisions of the chest wall defects of the patients were complicated by hypertrophic scar, redness, swelling, and sinus.Results:In surgery, the patient had (104±18) min of operation duration, (119±53) mL of intraoperative bleeding, (134±49) mL of cumulative drainage of drainage tube, and (5.3±1.7) days of drainage tube indwelling time. In two weeks after operation, all the grafted local flaps survived, and the color and texture of flaps were similar to the surrounding normal skin. One patient had fluid leakage from the incision of chest wall defect area with the incision partially dehisced, which healed well after a phase Ⅱ operation; no wound infection, subcutaneous hydrops, or wound rupture occurred in other patients. The incisions of donor sites in all the patients healed well and no wound disruption, local infection, or hematoma occurred. One month after operation, no new bone destruction was observed in the operative region by chest imaging examination. Patients were followed up for 6 to 96 months, with one patient having wound swelling, ulceration, and sinus in the operative area of the chest wall defect in 12 months after surgery, which healed after phase Ⅱ operation; the incisions of chest wall defect wounds in other patients healed well and had no scar, redness and swelling, or sinus.Conclusions:Partially de-epithelized local flap could be used in repairing tubercular chest wall defect wounds, with the advantages of flexible flap design, minimal donor site injury, and good postoperative wound healing.

Objective:To explore the mechanism of early pancreatic exocrine function changes in severely scalded rats.Methods:The experimental research methods was used. Eighty male Sprague-Dawley rats aged 7-8 weeks were divided into simple sham injury group ( n=8), sham injury+cholecystokinin octapeptide (CCK8) group ( n=8), severe scald+CCK8 group ( n=32), and extremely severe scald+CCK8 group ( n=32) by the random number table, which were treated accordingly. Immediately after injury of rats in the 2 sham injury groups and 1, 2, 3, and 7 days after injury of rats in the 2 scald groups, the improved methods including pancreatic duct puncture and catheterization were used to dynamically collect the pancreatic-bile juice (PBJ) of rats. The PBJ secretory volume within 1 h was recorded, and the content of pancreatic lipase, α-amylase, and trypsin in PBJ was detected by enzyme-linked immunosorbent assay (ELISA), and the number of samples was 8. The femoral venous blood was collected, and the concentrations of pancreatic lipase and α-amylase in serum were detected by standard colorimetry to reflect their activity ( n=8). The pancreatic tissue was extracted, and the levels of interleukin-1β (IL-1β) and IL-6 in pancreatic tissue were detected by ELISA ( n=8), the expression of hypoxia-inducible factor 1α (HIF-1α) in pancreatic tissue was detected by immunofluorescence method, and the histopathological changes in pancreatic tissue were observed by hematoxylin-eosin staining, the severity of pancreatic tissue injury in the 2 scald groups was evaluated by modified Schmidt method ( n=6), and the ultrastructure of acinar cells in pancreatic tissue was observed by transmission electron microscopy. Data were statistically analyzed with analysis of variance for factorial design, Tukey test, independent sample t test, and least significant difference test. Results:Compared with the PBJ secretory volume (0.740±0.030) mL in the pancreatic tissue of rats in simple sham injury group within 1 h immediately after injury, the (0.823±0.033) mL in sham injury+CCK8 group was significantly increased ( t=4.92, P<0.05). Compared with that of rats in sham injury+CCK8 group immediately after injury, the PBJ secretory volume of rats within 1 h in severe scald+CCK8 group ((0.681±0.024), (0.608±0.056), (0.525±0.025), and (0.720±0.044) mL) and extremely severe scald+CCK8 group ((0.540±0.025), (0.406±0.021), (0.475±0.036), and (0.690±0.018) mL) was significantly decreased on 1, 2, 3, and 7 days after injury ( P<0.05). Compared with that in severe scald+CCK8 group, the PBJ secretory volume of rats within 1 h in extremely severe scald+CCK8 group was significantly decreased on 1 and 2 days after injury ( P<0.05). Compared with that of rats in simple sham injury group immediately after injury, the content of pancreatic lipase, α-amylase, and trypsin in PBJ of rats in sham injury+CCK8 group immediately after injury was significantly increased (with t values of 4.56, 3.30, and 4.99, respectively, P<0.05). Compared with that of rats in sham injury+CCK8 group immediately after injury, the content of pancreatic lipase and α-amylase in PBJ of rats in severe scald+CCK8 group and extremely severe scald+CCK8 group was significantly decreased on 1, 2, 3, and 7 days after injury ( P<0.05), the trypsin content in PBJ of rats in extremely severe scald+CCK8 group was significantly decreased on 2 days after injury ( P<0.05). Compared with that in severe scald+CCK8 group, the content of pancreatic lipase in PBJ of rats in extremely severe scald+CCK8 group was significantly decreased on 1, 2, and 3 days after injury ( P<0.05), and the content of α-amylase and trypsin in PBJ was significantly decreased on 1 and 2 days after injury ( P<0.05). There were no statistically significant differences in the activities of pancreatic lipase and α-amylase in serum of rats among the 4 groups at various time points after injury ( P>0.05). Compared with that of rats in sham injury+CCK8 group immediately after injury, the levels of IL-1β in pancreatic tissue of rats in severe scald+CCK8 group on 1, 2, and 3 days after injury and in extremely severe scald+CCK8 group on 1, 2, 3, and 7 days after injury were significantly increased ( P<0.05), and the levels of IL-6 in pancreatic tissue of rats in severe scald+CCK8 group and extremely severe scald+CCK8 group were significantly increased on 1, 2, 3, and 7 days after injury ( P<0.05). Compared with that in severe scald+CCK8 group, the IL-1β level in pancreatic tissue of rats in extremely severe scald+CCK8 group was significantly increased on 2 and 3 days after injury ( P<0.05), and IL-6 level in pancreatic tissue was significantly increased on 2 days after injury ( P<0.05). The expression levels of HIF-1α in pancreatic tissue of rats in simple sham injury group and sham injury+CCK8 group immediately after injury were lower; and compared with that in sham injury+CCK8 group immediately after injury, the expression levels of HIF-1α in pancreatic tissue of rats in the 2 scald groups increased to a certain extent at different time points after injury, and the expression position was transited from the edge of the pancreatic tissue to the whole pancreas, the expression levels of HIF-1α in pancreatic tissue of rats in the 2 scald groups tended to be normal on 7 days after injury. Compared with that in simple sham injury group immediately after injury, the proportion of acinar cell cytoplasm in pancreatic tissue of rats in sham injury+CCK8 group was increased; and with the increase of time after injury, edema, hemorrhage, necrosis, and inflammatory infiltration appeared in pancreatic tissue of rats in the 2 scald groups. Compared with that in severe scald+CCK8 group, the scores of edema, inflammatory cell infiltration, bleeding, and necrosis in pancreatic tissue of rats in extremely severe scald+CCK8 group were increased to varying degrees at various time points after injury, and the scores of pancreatic tissue of rats in the 2 scald groups basically recovered to normal on 7 days after injury. Compared with that in simple sham injury group immediately after injury, the number of enzyme granules in acinar cells of pancreatic tissue of rats in sham injury+CCK8 group was increased, and with the increase of time after injury, the enzyme granules in acinar cells of rats in the 2 scald groups were gradually reduced basically. Conclusions:The exocrine functions of pancreas, such as synthesis and secretion of pancreatic enzymes, are decreased in the early stage in severely scalded rats. And the greater the scalded area, the more significant the decline of pancreatic exocrine function. This change may be related to hypoxic injury and inflammation in pancreatic tissue after severe scald.

Objective:To investigate the effects of gelatin methacrylate anhydride (GelMA) hydrogel loaded with small extracellular vesicles derived from human umbilical cord mesenchymal stem cells (hUCMSCs-sEVs) in the treatment of full-thickness skin defect wounds in mice.Methods:This study was an experimental study. hUCMSCs-sEVs were extracted by ultracentrifugation, their morphology was observed through transmission electron microscope, and the expression of CD9, CD63, tumor susceptibility gene 101 (TSG101), and calnexin was detected by Western blotting. The human umbilical vein endothelial cells (HUVECs), the 3 rd and 4 th passages of human epidermal keratinocytes (HEKs) and human dermal fibroblasts (HDFs) were all divided into blank control group (routinely cultured) and hUCMSC-sEV group (cultured with the cell supernatant containing hUCMSCs-sEVs). The cell scratch test was performed and the cell migration rates at 6, 12, and 24 h after scratching were calculated, the cell Transwell assay was performed and the number of migration cells at 12 h after culture was calculated, and the proportion of proliferating cells was detected by 5-acetylidene-2'-deoxyuridine and Hoechst staining at 24 h after culture, with sample numbers being all 3. The simple GelMA hydrogel and the GelMA hydrogel loaded with hUCMSCs-sEVs (hereinafter referred to as hUCMSC-sEV/GelMA hydrogel) were prepared. Then the micromorphology of 2 kinds of hydrogels was observed under scanning electron microscope, the distribution of hUCMSCs-sEVs was observed by laser scanning confocal microscope, and the cumulative release rates of hUCMSCs-sEVs at 0 (immediately), 2, 4, 6, 8, 10, and 12 d after soaking hUCMSC-sEV/GelMA hydrogel in phosphate buffer solution (PBS) were measured and calculated by protein colorimetric quantification ( n=3). Twenty-four 6-week-old male C57BL/6J mice were divided into PBS group, hUCMSC-sEV alone group, GelMA hydrogel alone group, and hUCMSC-sEV/GelMA hydrogel group according to the random number table, with 6 mice in each group, and after the full-thickness skin defect wounds on the back of mice in each group were produced, the wounds were performed with PBS injection, hUCMSC-sEV suspenson injection, simple GelMA coverage, and hUCMSC-sEV/GelMA hydrogel coverage, respectively. Wound healing was observed on post injury day (PID) 0 (immediately), 4, 8, and 12, and the wound healing rates on PID 4, 8, and 12 were calculated, and the wound tissue was collected on PID 12 for hematoxylin-eosin staining to observe the structure of new tissue, with sample numbers being both 6. Results:The extracted hUCMSCs-sEVs showed a cup-shaped structure and expressed CD9, CD63, and TSG101, but barely expressed calnexin. At 6, 12, and 24 h after scratching, the migration rates of HEKs (with t values of 25.94, 20.98, and 20.04, respectively), HDFs (with t values of 3.18, 5.68, and 4.28, respectively), and HUVECs (with t values of 4.32, 19.33, and 4.00, respectively) in hUCMSC-sEV group were significantly higher than those in blank control group ( P<0.05). At 12 h after culture, the numbers of migrated HEKs, HDFs, and HUVECs in hUCMSC-sEV group were 550 ±23, 235 ±9, and 856 ±35, respectively, which were significantly higher than 188 ±14, 97 ±6, and 370 ±32 in blank control group (with t values of 22.95, 23.13, and 17.84, respectively , P<0.05). At 24 h after culture, the proportions of proliferating cells of HEKs, HDFs, and HUVECs in hUCMSC-sEV group were significantly higher than those in blank control group (with t values of 22.00, 13.82, and 32.32, respectively, P<0.05). The inside of simple GelMA hydrogel showed a loose and porous sponge-like structure, and hUCMSCs-sEVs was not observed in it. The hUCMSC-sEV/GelMA hydrogel had the same sponge-like structure, and hUCMSCs-sEVs were uniformly distributed in clumps. The cumulative release rate curve of hUCMSCs-sEVs from hUCMSC-sEV/GelMA hydrogel tended to plateau at 2 d after soaking, and the cumulative release rate of hUCMSCs-sEVs was (59.2±1.8)% at 12 d after soaking. From PID 0 to 12, the wound areas of mice in the 4 groups gradually decreased. On PID 4, 8, and 12, the wound healing rates of mice in hUCMSC-sEV/GelMA hydrogel group were significantly higher than those in the other 3 groups ( P<0.05); the wound healing rates of mice in GelMA hydrogel alone group and hUCMSC-sEV alone group were significantly higher than those in PBS group ( P<0.05). On PID 8 and 12, the wound healing rates of mice in hUCMSC-sEV alone group were significantly higher than those in GelMA hydrogel alone group ( P<0.05). On PID 12, the wounds of mice in hUCMSC-sEV/GelMA hydrogel group showed the best wound epithelization, loose and orderly arrangement of dermal collagen, and the least number of inflammatory cells, while the dense arrangement of dermal collagen and varying degrees of inflammatory cell infiltration were observed in the wounds of mice in the other 3 groups. Conclusions:hUCMSCs-sEVs can promote the migration and proliferation of HEKs, HDFs, and HUVECs which are related to skin wound healing, and slowly release in GelMA hydrogel. The hUCMSC-sEV/GelMA hydrogel as a wound dressing can significantly improve the healing speed of full-thickness skin defect wounds in mice.

Objective:To explore the changes in entero-insular axis function and its role in mice with severe burns.Methods:This study was an experimental study. Ninety C57BL/6J male mice aged 8-10 weeks were divided into sham injury group and burn group (with 45 mice in each group) according to the random number table. A full-thickness scald (hereinafter referred to as burn) wound of 30% of the total body surface area was created on the back of mice in burn group, and the mice in sham injury group were simulated to cause a sham injury. Twenty-four hours after injury, the fasting blood glucose was measured ( n=12), followed by intraperitoneal glucose tolerance test and oral glucose tolerance test; the curve of blood glucose concentration changes over time was plotted, and the area under the curve was calculated ( n=6); the blood was taken from the heart before intraperitoneal injection or gavage of glucose solution and at 30, 60, and 120 minutes after intraperitoneal injection or gavage of glucose solution for measuring the plasma insulin and glucagon like peptide-1 (GLP-1) levels using enzyme-linked immunosorbent assay (ELISA), with a sample number of 3; the ileal tissue was taken from 3 mice in each group for detecting the GLP-1 expression and apoptosis levels of intestinal L cells by immunofluorescence staining and TdT-mediated dUTP nick-end labeling staining; the pancreatic islets were collected from 6 mice in each group for glucose-stimulated insulin secretion experiments. After incubation with low glucose (2.8 mmol/L glucose) and high glucose (16.7 mmol/L glucose), the supernatant was taken and the insulin level was detected using ELISA. Thirty-six C57BL/6J male mice aged 8-10 weeks were divided into sham injury group, burn group, and burn+exendin-4 (Ex-4) group (with 12 mice in each group) according to the random number table. The mice in sham injury group and burn group were subjected to the same corresponding treatment as before. The mice in burn+Ex-4 group were injured in the same way as the burn group mice followed by treatment with GLP-1 receptor agonist Ex-4. Twenty-four hours after injury, mouse pancreatic islets were collected, the protein expressions of heavy-chain binding protein (BIP), protein kinase R-like endoplasmic reticulum kinase (PERK), phosphorylated PERK (p-PERK), eukaryotic translation initiation factor 2α (eIF2α), phosphorylated eIF2α (p-eIF2α), and CCAAT/enhancer-binding protein homologous protein (CHOP) were detected using Western blotting, and the p-PERK/PERK and p-eIF2α/eIF2α ratios were calculated ( n=3), the apoptosis rate of pancreatic islet cells was detected using flow cytometry ( n=3), the glucose stimulated insulin secretion experiment was conducted as before to detect insulin levels in the supernatant ( n=6). Results:Twenty-four hours after injury, the fasting blood glucose of mice in burn group was (7.3±1.0) mmol/L, which was significantly higher than (5.1±0.6) mmol/L in sham injury group ( t=6.36, P<0.05). Twenty-four hours after injury, in the intraperitoneal glucose tolerance test and oral glucose tolerance test, the areas under the curve of blood glucose concentration changes over time of mice in burn group were significantly larger than those in sham injury group (with t values of 4.32 and 6.03, respectively, P<0.05); compared with those in sham injury group, the plasma insulin levels of mice before intraperitoneal injection of glucose solution and the plasma GLP-1 levels of mice before intraperitoneal injection or gavage of glucose solution in burn group were significantly decreased ( P<0.05), and the plasma levels of insulin of mice at 30, 60, and 120 minutes after intraperitoneal injection or gavage of glucose solution, as well as the plasma levels of GLP-1 of mice at 30 and 60 minutes after gavage of glucose solution were significantly decreased in burn group ( P<0.05). Twenty-four hours after injury, compared with those in sham injury group, the GLP-1 expression level of intestinal L cells of mice in burn group was significantly decreased ( t=7.74, P<0.05), and the apoptosis level was significantly increased ( t=14.28, P<0.05). Twenty-four hours after injury, the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn group was (8.5±0.4) ng/mg, which was significantly lower than (15.7±0.3) ng/mg in sham injury group ( t=18.68, P<0.05). Twenty-four hours after injury, compared with those in sham injury group, the protein expression levels of BIP, p-PERK/PERK, p-eIF2α/eIF2α, and CHOP in the pancreatic islets of mice in burn group were significantly increased ( P<0.05); compared with those in burn group, the protein expression levels of BIP, p-PERK/PERK, p-eIF2α/eIF2α, and CHOP in the pancreatic islets of mice in burn+Ex-4 group were significantly decreased ( P<0.05). Twenty-four hours after injury, the apoptosis rate of pancreatic islet cells of mice in burn group was (32.0±3.0)%, which was significantly higher than (10.3±2.5)% in sham injury group ( P<0.05); the apoptosis rate of pancreatic islet cells of mice in burn+Ex-4 group was (20.0±3.6)%, which was significantly lower than that in burn group ( P<0.05). Twenty-four hours after injury, the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn group was significantly lower than that in sham injury group ( P<0.05), while the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn+Ex-4 group was significantly higher than that in burn group ( P<0.05). Conclusions:After severe burns, the mice display dysfunction of the entero-insular axis, increased apoptosis of intestinal L cells, decreased synthesis and secretion of GLP-1, endoplasmic reticulum stress and increased apoptosis in pancreatic islet cells and a decrease in glucose-stimulated insulin secretion. The GLP-1 receptor agonist Ex-4 can protect the function of pancreatic islet cells of mice with severe burns, reducing the apoptosis level of pancreatic islet cells and promoting insulin secretion possibly via the alleviation of endoplasmic reticulum stress.