Lipopolysaccharide pretreatment inhibits LPS-induced human umbilical cord mesenchymal stem cell apoptosis via upregulating the expression of cellular FLICE-inhibitory protein.

Mesenchymal stem cell (MSC)-based regenerative therapy is currently regarded as a novel approach with which to repair damaged tissues. However, the efficiency of MSC transplantation is limited due to the low survival rate of engrafted MSCs. Lipopolysaccharide (LPS) production is increased in numerous diseases and serves an essential function in the regulation of apoptosis in a variety of cell types. Previous studies have indicated that low-dose LPS pretreatment contributes to cytoprotection. In the current study, LPS was demonstrated to induce apoptosis in human umbilical cord mesenchymal stem cells (hUCMSCs) via the activation of caspase, in a dose-dependent manner. Low-dose LPS pretreatment may protect hUCMSCs against apoptosis induced by high-dose LPS, by upregulating the expression of cellular FADD-like IL-1ß-converting enzyme-inhibitory protein (c-FLIP). The results of the present study indicate that pretreatment with an appropriate concentration of LPS may alleviate high-dose LPS-induced apoptosis.

Development of an Animal Model for Burn-Blast Combined Injury and Cardiopulmonary System Changes in the Early Shock Stage.

The purposes of this study were to establish an animal model for burn-blast combined injury research and elaborate cardiopulmonary system changes in the early shock stage. In this study, royal demolition explosive or RDX (hexagon, ring trimethylene nitramine) was used as an explosive source, and the injury conditions of the canine test subjects at various distances to the explosion (30, 50, and 70 cm) were observed by gross anatomy and pathology to determine a larger animal model of moderate blast injury. The canines were then subjected to a 35 % total body surface area (TBSA) full-thickness flame injury using napalm, which completed the development of a burn-blast combined injury model. Based on this model, the hemodynamic changes and arterial blood gas analysis after the burn-blast combined injury were measured to identify the cardiopulmonary system characteristics. In this research, RDX explosion and flame injury were used to develop a severe burn-blast injury animal model that was stable, close to reality, and easily controllable. The hemodynamic and arterial blood gas changes in the canine subjects after burn-blast injury changed distinctly from the burn and blast injuries. Blood pressure and cardiac output fluctuated, and the preload was significantly reduced, whereas the afterload significantly increased. Meanwhile, the oxygen saturation (SO2) decreased markedly with carbon dioxide partial pressure (PCO2), and lactic acid (Lac) rose, and oxygen partial pressure (PO2) reduced. These changes suggested that immediate clinical treatment is important during burn-blast injury both to stabilize cardiac function and supply blood volume and to reduce the vascular permeability, thereby preventing acute pneumonedema or other complications.

[Comparison of different methods for the isolation of human umbilical cord mesenchymal stem cells].

OBJECTIVE: To explore the most appropriate method for the isolation of human umbilical cord mesenchymal stem cells (MSCs) through a comparison of different methods. METHODS: Fifteen umbilical cord specimens from full-term healthy fetus with caesarean birth were completely rinsed with phosphate buffer saline (PBS) and sliced into 1 mm(3) tissue blocks after removal of umbilical vessels and external membrane. These tissue blocks were averagely divided into 4 groups after washing and centrifuge. Then four methods for the isolation of human umbilical cord MSCs were compared: an explant culture and three enzymatic methods of collagenaseII, collagenaseII/trypsin and collagenaseII/hyaluronidase. The count of living cells was evaluated by trypan blue dye exclusion test. Cell morphology was observed under inverted microscope. The expressions of cell surface markers CD105, CD90, CD73, CD31, CD44, CD45, human leukocyte antigen-I (HLA-I) and human leukocyte antigen class IImolecules (HLA-DR) were detected by immunofluorescent staining. Cell proliferation was assayed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT). RESULTS: The human umbilical cord MSCs were successfully isolated by four isolated methods. However the isolation method used profoundly altered the cell number and proliferation capacity of isolated cells. Isolated cells using four methods were counted at (5.44 ± 0.21)×10(5), (4.03 ± 0.24)×10(5), (4.91 ± 0.33)×10(5) and (5.94 ± 0.40)×10(5) respectively. More cells were obtained with collagenaseII/hyaluronidase than other three methods (all P < 0.05). Cells out of tissue blocks were observed at Day 9-11 and cells were observed at Day 2 with three types of enzyme digestion. The fusion time of cells were (18.5 ± 3.5), (8.0 ± 1.0), (7.5 ± 1.5) and (3.5 ± 0.5) days respectively. The fusion time of cells obtained with collagenaseII/hyaluronidase was lower than other methods (all P < 0.05). Cell morphology: polygonal, irregular and of large volume for explant culture; relatively short and small for collagenaseII and collagenaseII/trypsin methods; thin spindle for collagenaseII/hyaluronidase method. Immunofluorescent staining revealed that CD105, CD73, CD90 and CD44 were expressed in all groups while there was no expression of CD31, CD45 or HLA-DR. And the cells obtained with collagenaseII/hyaluronidase method were in a higher cell proliferation rate and activity compared to other methods. CONCLUSION: The collagenaseII/hyaluronidase method is optimal for the isolation of human umbilical cord MSCs than other methods.

Basic fibroblast growth factor/vascular endothelial growth factor in the serum from severe burn patients stimulates the proliferation of cultured human umbilical cord mesenchymal stem cells via activation of Notch signaling pathways.

BACKGROUND: Mesenchymal stem cells (MSCs) are the leading cellular constituents used in regenerative medicine. MSCs repair and reconstruct wounds of acute traumata and radiation-induced burns through proliferation, differentiation, and trophic activity. However, repair effect of MSCs on severe burn wounds remain to be clarified because severe burns are much more complex traumata than radiation-induced burns. Survival and proliferation of MSCs in microenvironments affected by severe burns are very important for improving wound repair/regeneration. This study aimed to elucidate the survival and proliferation effects and the potential proliferation mechanism of serum from severe burn patients (BPS) on human umbilical cord MSCs (hUCMSCs) in vitro. METHODS: The hUCMSCs were isolated, cultured, and identified. Next, we evaluated the effects of BPS on cell numbers, cell cycle progression, cyclin D expression, and key proteins and genes of the Notch signaling pathway. Putative mechanisms underlying the proliferation of hUCMSCs were investigated. RESULTS: BPS markedly increased the number of hUCMSCs, and the results of the cell cycle studies indicated that BPS induced cell cycle progression into the M phase. Cyclin D expression was higher with BPS than in the control group. Moreover, Notch-1, a key determinant of hUCMSC activation and proliferation, and its target gene Hes-1 were overexpressed after BPS treatment. Proliferation numbers of hUCMSC, rate of proliferation period (G2/M+S), and the expression of cyclin D, Notch-1, and Hes-1 were markedly decreased by Notch signaling inhibitors (DAPT/GSI). In the case of BPS, basic fibroblast growth factor and vascular endothelial growth factor were the key factors that promoted hUCMSC proliferation. CONCLUSION: This study provides novel evidence for the role of BPS in the survival and rapid proliferation of hUCMSCs and suggests that these cells could be used for cell therapy-based clinical applications for treating severe burns. Furthermore, hUCMSC proliferation was induced by basic fibroblast growth factor/vascular endothelial growth factor in BPS through activation of Notch signal.

[Functions of exogenous application of connective tissue growth factor in stimulating human dermal papilla cells and human hair follicle outer root sheath cells for reconstructive tissue-engineering hair follicles].

OBJECTIVE: To explore the functions of connective tissue growth factor (CTGF) in the restoration of hair follicles with a mixture of human dermal papilla cells and human hair follicle outer root sheath cells in vitro in nude mice. METHODS: Human hair follicle outer root sheath cells (hfORS) and human hair dermal papilla cells (hDP) were cultured in vitro and mixed in a fixed ratio (hfORS: hDP = 5:1). Flow cytometry was used to detect the content of CD200(+) cells in human hair follicle outer root sheath cells.And 8 nude mice were divided randomly into 2 groups according to a random number table and back wounds produced. Group A was transplanted with cell mixture plus 20 µg/L CTGF. Group B was transplanted with cell mixture alone. After 8 weeks of transplantation, the development of hair follicle formation was observed histologically.PCR was used to detect the expression of human specific DNA and mice DNA in transplants. RESULTS: The portion of CD200(+) cells in cultured hfORS was 19.65%. At 8 weeks after implantation, hair follicle formation could be observed in Group A (268 ± 96) more than Group B (62 ± 20). The difference was statistically significant (P < 0.05). And PCR showed that there was human composition in transplant. CONCLUSION: CTGF can induce the formation of hair follicle by promoting the interference between hDP and hfORS.

[Voltage dependent anion channel 2 involved mitochondrial apoptosis and its possible regulatory signal pathway in hearts of rats with severe scalds].

OBJECTIVE: To explore the role of voltage dependent anion channel 2 (VDAC2) involved mitochondrial apoptosis in heart injury of rats with severe scald injury and elucidate its possible regulatory signal pathway. METHODS: A total of 60 Wistar rats were divided into sham scald group (n = 30) and scald group (n = 30) according to a random digital table. Blood and heart tissue samples were harvested at Day 1, 7, 14 post scalding. Myocardial injury was assessed with cardiac troponin I (cTnI) by enzyme-linked immunosorbent assay (ELISA). Mitochondrial apoptosis activation was evaluated by the expressions of Bax/Bcl-2 ratio, cytoplasmic cytochrome C and VDAC2. And the levels of phosphatidylinositol 3-kinase, p-Glycogen Synthase Kinase-3ß and hexokinase 2 protein were determined by Western blot. RESULTS: The serum levels of cTnI were significantly higher in scald group than those in sham scald group at Day 1, 7, 14 ((1.41 ± 0.25) vs (0.53 ± 0.23) µg/L, (1.93 ± 0.53) vs (0.43 ± 0.23) µg/L, (1.62 ± 0.34) vs (0.41 ± 0.22) µg/L respectively, all P < 0.05). Compared with sham scald group, Bax/Bcl-2 ratio increased significantly in scald group at Day 1, 7 day post-scalding (3.360 ± 0.173 vs 0.623 ± 0.044, 2.736 ± 0.341 vs 0.698 ± 0.064, 1.290 ± 0.234 vs 0.718 ± 0.063 respectively, all P < 0.05), VDAC2 protein level in scald group decreased significantly at Day 1, 7, 14 (0.070 ± 0.009 vs 0.328 ± 0.026, 0.007 ± 0.002 vs 0.291 ± 0.025, 0.009 ± 0.004 vs 0.302 ± 0.037 respectively, all P < 0.05), the cytoplasmic levels of cytochrome increased significantly in scald group at Day 1, 7, 14 (0.418 ± 0.030 vs 0.022 ± 0.007, 1.685 ± 0.169 vs 0.030 ± 0.011, 0.300 ± 0.037 vs 0.098 ± 0.014 respectively, all P < 0.05), the expression of PI3K was significantly lower in scald group at Day 14 post-scalding (0.083 ± 0.015 vs 0.328 ± 0.011, P < 0.05), the expressions of p-GSK3ß all reduced significantly at Day 1, 7, 14 (0.098 ± 0.014 vs 0.446 ± 0.031, 0.064 ± 0.002 vs 0.476 ± 0.054, 0.074 ± 0.010 vs 0.442 ± 0.041, respectively, all P < 0.05) and the expressions of HK2 were lower at Day 7, 14 post-scalding (0.390 ± 0.027 vs 0.611 ± 0.070, 0.267 ± 0.018 vs 0.490 ± 0.042, respectively, all P < 0.05). CONCLUSIONS: VDAC2 involved mitochondrial apoptosis is activated in myocardium after severe scalds. And it may be regulated by the pathway of PI3K-GSK-HK2.

[Changes in proliferative activity of myoblasts and expression of Akt in skeletal muscle of rats after severe burn injury].

OBJECTIVE: To investigate changes in proliferative activity of myoblasts in skeletal muscle and potential role of phosphorylated Akt on it, so that a better understanding in mechanisms of skeletal muscle atrophy after burn injury will be got. METHODS: One hundred and twenty Wistar rats were randomly divided into 2 groups: control and severe thermal injury group. Rats in severe thermal injury group were subjected to a 40% total body surface area full-thickness scald injury, and Tibialis Anterior (TA) muscles were collected on 0, 1, 4, 7, 10, 14 days post-injury. After muscle mass determined, immunohistochemical double staining was used for detection of Proliferative Cell Nuclear Antigen (PCNA) of myoblasts. Protein expression of total Akt and phosphorylated Akt was determined by Western Blot. RESULTS: Burn injury induced significant reduction of TA muscle mass and maximal reduction of it appeared by 4 days after injury (P < 0.01). Proliferative activity of myoblasts decreased significantly from the first day post-injury (P < 0.01) and increased slowly to basal level of controls after 7 days post-injury. The phosphorylated Akt was undetectable in both of controls and injured samples before 4 days but increased significantly after 7 days post-injury (P < 0.01), though total Akt expression had no significant alteration at any time points (P > 0.05). CONCLUSIONS: Decrease in proliferative activity of myoblasts may be one of the contributors of significant atrophy of skeletal muscle after burn injury. Effect of phosphorylated Akt on proliferation attenuated in early stage and increased significantly in later stage after burn injury may partly explain the changes in proliferative activity of myoblasts.

[Effect of intensive insulin therapy on apoptosis-related ligands in serum in rats with severe scald].

OBJECTIVE: To investigate changes in apoptosis-related ligands in serum in rats with severe scald and the effect of intensive insulin therapy on the changes. METHODS: One hundred and fifty Wistar rats were randomly divided into 3 groups: sham burn (SB), scald (S) and treatment (T) groups. Rats in S and T groups were inflicted with 40% TBSA full-thickness burn, followed by intraperitoneal injection with 40 mL/kg of isotonic saline for resuscitation. Rats in T group were subcutaneously injected insulin in a dose of 0.25 U/100 g 24 hours after burn injury, and every 12 hours for 5 days (0.25, 0.50, 0.75, 1.00, 1.25 U/100 g each day, respectively) to control the level of blood glucose between 3 and 6 mmol/L. Rats in SB group were sham scalded at 37 degrees C without resuscitation. Blood was drawn from abdominal aorta on 1, 4, 7, 10, 14 post burn day (PBD) for determination of serum levels of TNF-alpha, soluble Fas ligand (sFasL) and soluble Fas receptor (sFas) by enzyme-linked immunosorbent assay (ELISA), and insulin by radioimmunity assay (RIA). RESULTS: The serum level of TNF-alpha in S group peaked on 1 PBD (30.9 +/- 8.7) ng/L, which showed statistically significant difference when compared with that of SB and T groups (12.7 +/- 2.8) ng/L, (16.8 +/- 4.7) ng/L, respectively, P < 0.01), then lowered gradually to become similar to that of SB group on 7 PBD. The level of TNF-alpha in T group increased gradually, but was obviously lower than that of S group on 1, 4, 7 PBD (P < 0.01). The level of sFasL in S (on 7-14 PBD) and T (4-10 PBD) groups was significantly higher than that in SB group (P < 0.05), then lowered to normal level. The levels of sFas on 4-10 PBD in T group were obviously higher than that in S and SB group (P < 0.05). Ratio of sFasL to sFas in serum of S group was higher than that in SB group on 7, 10 PBD, which was higher than that in T group on 7 PBD (P < 0.05). There was significant decrease in serum level of insulin in S group compared with that of SB group on 4-10 PBD (P < 0.05). The level of insulin in T group increased on 1 PBD, peaked on 4 PBD (327 +/- 15 microU/mL), which was significantly higher than that in SB and S groups (42 +/- 15, 28 +/- 10 microU/mL, respectively, P < 0.01), then decreased gradually to normal level. CONCLUSIONS: Insulin may inhibit apoptosis after burn by down-regulating secretion of apoptotic ligands.

[Preliminary study of skeletal muscle apoptosis after severe thermal injury in rats].

OBJECTIVE: To investigate changes in skeletal muscle apoptosis after a severe thermal injury in rats. METHODS: One hundred Wistar rats were randomly divided into two groups: sham thermal injury group and severe thermal injury group. They were subdivided into 1, 4, 7, 10, 14 days post-injury with 10 rats in each subgroup. Rats in severe thermal injury group were subjected to a 40% total body surface area full-thickness scald injury. Both weight and tibialis anterior (TA) mass of rats were weighed on 1, 4, 7, 10, 14 days post-injury. Electron microscope was used for observing ultrastructural changes in skeletal muscle, including apoptosis. Tissues of tibialis anterior from burn and sham burn animals were then examined by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and immunohistochemistry. RESULTS: Compared with sham thermal injury group, body weight and TA mass of rats were decreased from first day on, and it dropped to the lowest level at 4 days (P<0.05 and P<0.01), and started to regain from 7 days on (all P<0.01). Electron micrographs showed condensation of chromatin around the periphery of the nucleus, blebbing of the sarcolemma, and free of myofibrils near myonuclei in a large area in skeletal muscle of thermally injured rats. Sporadic TUNEL positive myonuclei were also seen under light microscope in skeletal muscle in thermal injury group. There were no characteristic signs of apoptosis in skeletal muscle in rats of sham group. CONCLUSION: There are skeletal muscle apoptosis after severe thermal injury. It may contribute to atrophy of skeletal muscle after burn injury in rats.

[Investigation of p53 gene mutations in keloids using PCR-SSCP].

OBJECTIVE: To detect gene mutations of p53 gene (exon 4-6) in fibroblasts. METHODS: Samples of keloids were taken from 15 patients. The mutations of p53 gene were detected using polymerase chain reaction, the single-strand conformational polymorphism(SSCP) analysis and DNA sequencing. RESULTS: Gene mutations in p53 gene exon 4, 5, and 6 were identified in all the patients with keloids. CONCLUSION: Gene mutations resulted in keloid p53 protein losing its functions of suppressing cell processes and conducting apoptosis.

[Cell cycle analysis and P53 gene mutation detection of fibroblasts derived from the surrounding skin of keloids].

OBJECTIVE: To investigate whether there are abnormal fibroblasts in the surrounding skin of keloids for better understanding of the etiological feature of keloids. METHODS: Fresh samples were used for cell culture. Flow cytometry was used for analyzing cell cycles of fibroblasts derived from keloids and the surrounding skin. Proliferative cell proportions were compared between every two groups. P53 exon 4, 5 and 6 were amplified by PCR. DNA was sequenced to examine the structure of the destination gene. RESULTS: The proliferative cell proportion of the fibroblasts derived from the surrounding skin is not so high as that from the verge of keloids, but is higher than the normal skin fibroblasts derived from other part of the keloid patients or persons without keloids (P < 0.05). Mutations (point and frameshift mutations) of P53 exon 4 (6/6) and exon 5(2/6) in fibroblasts derived from the surrounding skin of keloids were identified. Fibroblasts derived from keloids have the same mutations as its surrounding skin. CONCLUSION: There are abnormal fibroblasts in the surrounding skin of keloids. It may be the consequence of keloid infiltrative growth and a reason of easy recurrence of keloid after therapy.

[Study on the injurious effect of a self designed micro-skin machine on the epithelia].

OBJECTIVE: To observe the injury on micro-skin induced by a self designed micro-skin machine. METHODS: Micro-skin was produced either with the machine or by hand. Cells at the edge of micro-skin were observed by transmission electron microscope. succinic dehydrogenase activity in supernatant of cultivated cells was analyzed, and the cell proliferation of micro-skin was assessed by (3)H-TdR. Twenty patients were enrolled in the study for the observation of the wound healing time between the two groups of micro-skin after being grafted. RESULTS: Transmission electron microscope examination revealed that the cellular injury at the edge of the micro-skin in machine-made group was mild compared with that in man-made group. (3)H-TdR rate was elevated but the activity of succinic dehydrogenase in the supernatant of cultured cells decreased in supernatant of cultured cells of machine produced micro-skin. Wound healing time was shortened in machine made group. (P < 0.05). CONCLUSION: The cellular injury at the edge of micro-skin in the machine made group was mild when compared with that in the man-made group with cell proliferation accelerated and wound healing time shortened.

[Detection and analysis of Fas gene (exon 1-6) mutations in keloids].

OBJECTIVE: To detect Fas DNA mutations (exon 1-6) in the fibroblasts of patients with keloids, thereby to understand the clinicopathological implications of altered structure of the keloids. METHODS: PCR followed by single-strand conformational polymorphism analysis and direct DNA sequencing were used to detect Fas gene mutations in 15 patients with keloids. RESULTS: Insertion and point mutations were identified on the boundary between intron 5 and exon 6 in two patients, while no Fas mutations were found in the fibroblasts derived from normal skin samples of any of the patients. CONCLUSION: Nonfunction of Fas protein may be related to aberrant gene structure that codes for the transmembrane domain.