Future application of hair follicle stem cells: capable in differentiation into sweat gland cells

BACKGROUND

Sweat glands (SGs) can not regenerate after complete destruction in the severe skin injury, so it is important to find a ideal stem cell source in order to regenerate functional SGs. Hair follicle stem cells (HFSCs) possess the obvious properties of the adult stem cells, which are multipotent and easily accessible. In this research, we attempted to direct the HFSCs suffered from the sweat gland cells (SGCs) special differentiation by a co-operative coculture system in vitro.

METHODS

The designed co-culture microenvironment in the transwell was consist of two critial factors: heat shocked SGCs and dermis-like mesenchymal tissue, which appeared independently in the two control groups; after induction, the purified induced SGC-like cells were transplanted into the full-thickness scalded wounds of the nude mice, after 4 weeks, the reconstructed SG-like structures were identified by immunohistochemical and immunofluorescence analysis.

RESULTS

A part of HFSCs in experimental group finally expressed SGCs phenotypes, by contrast, the control group 1 which just containing dermis-like mesenchymal tissue failed and the control group 2 consisted of heat shocked SGCs was in a poor efficiency; by immunofluorescence staining and flow cytometry analysis, the expression of HFSCs special biomarkers was down regulated, instead of the positive efficiency of SGCs special antigens increased; besides, the induced SGCs displayed a high expression of ectodysplasin A (EDA) and ectodysplasin A receptor (EDAR) genes and proteins; after cell transplantation, the youngest SG-like structures formed and be positive in SGCs special antigens, which never happened in untreated wounds (P < 0.05).

CONCLUSION

The HFSCs are multipotential and capable in differentiating into SGCs which promise a potential stem cells reservoir for future use; our special co-culture microenvironment is promising for HFSCs differentiating; the induced SGCs are functional and could work well in the regeneration of SGs.

[Identification and cell phenotype transdifferentiation of adipose-derived stem cells]

OBJECTIVE

To investigate the transdifferentiation of the ADSCs to epidermal cells.

METHODS

ADSCs were isolated and cultured from rat adipose tissue by digestion of enzyme. ADSCs was identified by immunocytochemistry and flow cytometry. ADSCs were divided into four groups in order to induce: the condition medium (containing 30% superior of homogenizing rat skin in 10% FBS/DMEM) group, 7 days; 10% FBS/DMEM with EGF (20 ng/ml) group, 7 days; the condition medium for 4 days and then 10% FBS/DEME instead of the condition medium for 3 days group; 10% FBS/DMEM for 7 days group (control group). Cytokeratin 19 and cytokeratin 10 expressions in ADSCs were detected by flow cytometry.

RESULTS

(1) The results of immunocytochemistry showed that ADSCs were positive for CD49d and negative for CD106, CD34, CD19, CD10. The results of flow cytometry showed ADSCs were positive for CD49d and CD44. (2) The CK19 expression of ADSCs was 45.32% in the condition medium group, 26.58% in the condition medium with EGF group, 23.37% in te condition medium for 4 days and then 10% FBS/DMEM instead of the condition medium for 3 days gropu and 18.53% in control group, P <0.01. The CK10 expression of ADSCs was 43.56% in the condition medium group, 25.54% in the condition medium with EGF group, 18.20% in the condition medium for 4 days and then 10% FBS/DMEM instead of the condition medium for 3 days group and 2.46% in control group, P < 0.01.

CONCLUSIONS

The superior of homogenizing rat skin can induce CK19 and CK10 expressing in ADSCs, and thereby demonstrating ADSCs can differentiate to epidermal cell phenotype in vitro.

Non-mitogenic acidic fibroblast growth factor reduces intestinal dysfunction induced by ischemia and reperfusion injury in rats

BACKGROUND

Acidic fibroblast growth factor (aFGF) has potentially therapeutic uses in some diseases, but the mitogenic activity of aFGF has been found to contribute to several human pathologies, so the extensive applications of wild-type aFGF have been limited. The purpose of the present study was to explore the effects and mechanisms of wild-type (aFGF) and non-mitogenic aFGF on gut ischemia-reperfusion injury in rats.

METHODS

Rat intestinal ischemia-reperfusion injury (I/R) was produced by clamping the superior mesenteric artery (SMA) for 45 min followed by reperfusion. One hundred and fourteen rats were randomly divided into four groups: sham operation (group C, n = 6), intestinal I/R + 0.1 mL saline (group S, n = 36), intestinal I/R + 4 microg/0.1 mL wild-type aFGF (group W, n = 36) and intestinal I/R + 4 microg/0.1 mL modified aFGF (i.e. non-mitogenic aFGF; group M, n = 36). According to different periods after reperfusion, groups S, W and M were further divided into 0.5-, 1-, 2-, 6-, 12- and 24-h subgroups. The contents of D-lactate and nitrite/nitrate were determined, the changes of intestinal histology were analyzed, the protein expressions of caspase-3, extracellular signal-regulated kinase (ERK)1/2, and p38 were detected by western blot, and apoptotic cells were examined by the terminal deoxynucleotidyl transferase (TdT)-mediated dUDP-biotin nick end labeling (TUNEL) assay at 0.5, 1, 2, 6, 12 and 24 h after I/R, respectively.

RESULTS

Compared with rats in group S, intestinal histological damage, apoptotic index, d-lactate content and nitrite/nitrate level all decreased significantly in group W and group M rats. However, there was no difference between rats treated with wild-type aFGF and those with non-mitogenic aFGF. The protein expression of caspase-3, ERK1/2, and p38 in saline-treated rats was higher than those in aFGF-treated rats.

CONCLUSIONS

Both types of aFGF had protective effects on gut I/R and there was no significant difference between the two aFGF. The protective effects of aFGF may come from the non-mitogenic activity rather than the mitogenic activity of aFGF in tissue repair, indicating a potentially clinical use for the non-mitogenic effects of aFGF in preventing visceral organ injury triggered by I/R injury in the future.

Recombinant human platelet-derived growth factor enhanced dermal wound healing by a pathway involving ERK and c-fos in diabetic rats

BACKGROUND

Platelet-derived growth factor (PDGF) has been shown to promote dermal wound healing, however, the molecular mechanisms responsible for are not fully understood.

OBJECTIVE

The present study was undertaken to investigate the possible signaling mechanisms by which PDGF improved healing of cutaneous wound in diabetic rats.

METHODS

Four full-thickness skin wounds were created on the dorsum of Wistar diabetic rats. Animals were treated with or without recombinant human PDGF (rhPDGF) at 7.0 microg/cm(2) wound or vehicle daily 1 day after wounding. The animals were then killed after various intervals of wounding, and the wounded skin tissues were used for histological evaluation, analysis of the phosphorylation of extracellular signal-regulated kinases (ERK) and the expression of c-fos protein, as well as the labeling indices of proliferative cell nuclear antigen (PCNA).

RESULTS

Topical application of rhPDGF significantly accelerated the rate of reepithelialization compared with vehicle-treated or untreated group at 7 days after wounding. At the histological level, the significant increases in the degree of reepithelialization, the thickness of granulation tissue and the density of capillary bud were observed in the wound sites in rhPDGF-treated group at 7 and 14 days after wounding. Moreover, treatment with rhPDGF increased PCNA labeling indices, c-fos protein expression and ERK phosphorylation in the wounded tissues at the indicated time after wounding.

CONCLUSION

These results suggest that application of rhPDGF increases cell proliferation, and enhances dermal tissue repair in diabetic skin lesion of rats, which might be partly mediated by ERK activation and c-fos protein expression.

Exogenous acid fibroblast growth factor inhibits ischemia-reperfusion-induced damage in intestinal epithelium via regulating P53 and P21WAF-1 expression

AIM

To detect the effect of acid fibroblast growth factor (aFGF) on P53 and P21WAF-1 expression in rat intestine after ischemia-reperfusion (I-R) injury in order to explore the protective mechanisms of aFGF.

METHODS

Male rats were randomly divided into four groups, namely intestinal ischemia-reperfusion group (R), aFGF treatment group (A), intestinal ischemia group (I), and sham-operated control group (C). In group I, the animals were killed after 45 min of superior mesenteric artery (SMA) occlusion. In groups R and A, the rats sustained for 45 min of SMA occlusion and were treated with normal saline (0.15 mL) and aFGF (20 mug/kg, 0.15 mL), then sustained at various times for up to 48 h after reperfusion. In group C, SMA was separated, but without occlusion. Apoptosis in intestinal villi was determined with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling technique (TUNEL). Intestinal tissue samples were taken not only for RT-PCR to detect P53 and P21WAF-1 gene expression, but also for immunohistochemical analysis to detect P53 and P21WAF-1 protein expression and distribution.

RESULTS

In histopathological study, ameliorated intestinal structures were observed at 2, 6, and 12 h after reperfusion in A group compared to R group. The apoptotic rates were (41.17+/-3.49)%, (42.83+/-5.23)%, and (53.33+/-6.92)% at 2, 6, and 12 h after reperfusion, respectively in A group, which were apparently lower than those in R group at their matched time points (50.67+/-6.95)%, (54.17+/-7.86)%, and (64.33+/-6.47)%, respectively, (P<0.05)). The protein contents of P53 and P21WAF-1 were both significantly decreased in A group compared to R group (P<0.05) at 2-12 h after reperfusion, while the mRNA levels of P53 and P21WAF-1 in A group were obviously lower than those in R group at 6-12 h after reperfusion (P<0.05).

CONCLUSION

P53 and P21WAF-1 protein accumulations are associated with intestinal barrier injury induced by I-R insult, while intravenous aFGF can alleviate apoptosis of rat intestinal cells by inhibiting P53 and P21WAF-1 protein expression.

Analysis of differentially expressed genes in fetal skin of scarless and scar-forming periods of gestational rats

OBJECTIVE

To study the differences of gene expression between earlier gestational skin and later gestational skin of rats with the aids of single primer amplification (SPA) and high-density oligonucleotide DNA array to understand the molecular mechanism of scarless healing.

METHODS

Total RNAs were isolated from fetal rat skin of the scarless (E15) and scar-forming (E18) periods of gestation (term = 21.5 days). The RNAs from earlier gestational skin (EGS) and later gestational skin (LGS) were both reversely transcribed to cDNAs, then labeled with the incorporation of fluorescent dCTP for preparing the hybridization probes by SPA method. The mixed probes were then hybridized to the oligonucleotide DNA arrays which contained 5,705 probes representing 5,705 rat genes. After highly stringent washing, these DNA arrays were scanned for fluorescent signals to display the differentially expressed genes between the 2 groups of skin.

RESULTS

Among 5,705 rat genes, there were 53 genes (0.93 percent) with differentially expressed levels between EGS and LGS groups, 27 genes, including fibroblast growth factor 2 (FGF2) and follistatin were up-regulated (0.47%) and 26 genes were down-regulated (0.46%) in fetal skin during scarless period versus scar-forming period. Higher expressions of FGF2 and follistatin in EGS than those in LGS were also revealed by RT-PCR method.

CONCLUSIONS

High-density oligonucleotide DNA array provided a powerful tool for investigating differential gene expression in earlier and later gestational fetal skins. This technology validates that the mechanism of fetal scarless healing is very complicate and the change of many gene expressions is associated with fetal scarless healing.

Ontogeny of expression of basic fibroblast growth factor and its receptors in human fetal skin

OBJECTIVE

To investigate the expression characteristics of basic fibroblast growth factor (bFGF) and its receptors, flg (FGFR1) and bek (FGFR2), in fetal skin at different gestational ages underlying the relevance of these 3 proteins to skin development and the mechanisms underlying the phenotypic transition from scarless to scar-forming healing.

METHODS

Eighteen specimens of fetal skin biopsies of human embryo were obtained from spontaneous abortions at different gestational ages of 13-32 weeks. Gene expression of bFGF, bek and flg was examined with reverse transcription-polymerase chain reaction (RT-PCR). The dynamic expression and distribution of these 3 proteins were detected with streptavidin peroxidase (SP) immunohistochemical staining method.

RESULTS

In the early gestational fetal skin, genes of bFGF and flg were strongly expressed and more protein contents of these 2 proteins were found as compared with the genes at late gestation fetal skin (2.446+/-0.116 and 2.066+/-0.152 versus 2.157+/-0.101 and 1.818+/-0.086, respectively, P<0.05). On the contrary, the levels of gene expression and protein content of bek were not differently expressed in the early gestational fetal skin versus the late ones. Protein particles of bFGF were mainly distributed in the epidermal cells and some fibroblasts. Bek was mainly located in the cell membrane and cytoplasm of epidermal cells while flg protein was principally located in the epidermal cells, endothelial cells and some fibroblasts.

CONCLUSIONS

The endogenous bFGF and their receptors might be involved in the cutaneous development at fetal stage. The differently expressing levels of bFGF and flg during gestation may be related to scarless or scar-forming repair during gestation.

Acid fibroblast growth factor reduces rat intestinal mucosal damage caused by ischemia-reperfusion insult

AIM: To detect the effects of acid fibroblast growth factor (aFGF) on apoptosis and proliferation of intestinal epithelial cells in differentiation or proliferation status to explore the protective mechanisms of aFGF.

METHODS: Wistar rats were randomly divided into sham-operated control group (C, n = 6), intestinal ischemia group (I, n = 6), aFGF treatment group (A, n = 48) and intestinal ischemia-reperfusion group (R, n = 48). Apoptosis of intestinal mucosal cells was determined with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) technique. Proliferating cell nuclear antigen (PCNA) protein expression and distribution were detected with immunohistochemical method. Plasma levels of D-lactate were determined with modified Brandts method.

RESULTS: In A group, administration of exogenous aFGF could improve intestinal histological structure and decrease plasma D-lactate levels at 2-12 h after the reperfusion compared with R group. The apoptotic rates and PCNA protein expressions were not increased until 2 h after reperfusion and were maximal at 12 h. After reperfusion for 2-12 h, the apoptotic rates were gradually augmented along the length of jejunal crypt-villus units. Administration of aFGF could significantly reduce the apoptotic response at 2-12 h after reperfusion (P<0.05). Apoptosis rates in villus and crypt epithelial cells in A group at 12 h after reperfusion were (62.5±5.5)% and (73.2±18.6)% of those in R group, respectively. Treatment of aFGF could apparently induce protein expression of PCNA in intestinal mucosal cells of A group compared with R group during 2-12 h after reperfusion (P<0.05). There were approximately 1.3- and 1.5-times increments of PCNA expression levels in villus and crypt cells in A group at 12 h after reperfusion compared with R group, respectively.

CONCLUSION: Intestinal I/R insult could lead to histological structure change and apoptotic rate increment. The protective effects of aFGF against ischemia/reperfusion in rat intestinal mucosa might be partially due to its ability to inhibit ischemia/reperfusion-induced apoptosis and to promote cell proliferation of crypt cells and villus epithelial cells.

Intravenous acid fibroblast growth factor protects intestinal mucosal cells against ischemia-reperfusion injury via regulating Bcl-2/Bax expression

AIM: To detect the effect of acid fibroblast growth factor (aFGF) on apoptosis and gene expression of bax and bcl-2 gene in rat intestine after ischemia/reperfusion (I/R) injury, and to explore the protective mechanisms of aFGF.

METHODS: One hundred and eight Wistar rats were randomly divided into sham-operated control group (C) (n = 6), intestinal ischemia group (I) (n = 6), aFGF treatment group (A) (n = 48) and intestinal ischemia-reperfusion group (R) (n = 48). In group I, the animals were killed after 45 min of superior mesenteric artery (SMA) occlusion, while in groups R and A, the rats sustained 45 min of SMA occlusion and were then treated with normal saline and aFGF, respectively, sustained 15 min, 30 min, 1, 2, 6, 12, 24, or 48 h of reperfusion, respectively. In group C, SMA was separated, but without occlusion. Apoptosis in intestinal villus was determined with terminal deoxynucleotidyl transferase mediated dUTP-biotin nick-end labeling technique (TUNEL). Intestinal tissue samples were taken not only for detection of bax and bcl-2 gene expression by RT-PCR, but also for detection of bax and bcl-2 protein expression and distribution by immunohistochemical analysis.

RESULTS: The rat survival rates in aFGF treated group were higher than group R (P<0.05) and the improvement of intestinal histological structures was observed at 2, 6, and 12 h after the reperfusion in group A compared with group R. The apoptotic rates were (41.17±3.49)%, (42.83±5.23)% and (53.33±6.92)% at 2, 6 and 12 h after reperfusion, respectively in group A, apparently less than those of group R at matched time points (50.67±6.95, 54.17±7.86, 64.33±6.47, respectively) (P<0.05). The bax gene transcription and translation were significantly decreased in group A vs group R, while mRNA and protein contents of Bcl-2 in group A were obviously higher than those in group R during 2-12 h period after reperfusion.

CONCLUSION: The changes in histological structure and the increment of apoptotic rate indicated that the intestinal barrier was damaged after intestinal I/R injury, whilst intravenous aFGF could alleviate apoptosis induced by ischemia and reperfusion in rat intestinal tissues, in which genes of bax and bcl-2 might play important roles.

Inhibition of p38 mitogen-activated protein kinase may decrease intestinal epithelial cell apoptosis and improve intestinal epithelial barrier function after ischemia- reperfusion injury

AIM: To investigate the role of p38 mitogen-activated protein kinase in rat small intestine after ischemia-reperfusion (I/R) insult and the relationship between activation of p38 MAPK and apoptotic cell death of intestine.

METHODS: Ninety Wistar rats were divided randomly into three groups, namely sham-operated group (C), I/R vehicle group (R) and SB203580 pre-treated group (S). In groups R and S, the superior mesenteric artery (SMA) was separated and occluded for 45 min, then released for reperfusion for 0.25, 0.5, 1, 2, 6, 12 and 24 h. In group C, SMA was separated without occlusion. Plasma D-lactate levels were examined and histological changes were observed under a light microscope. The activity of p38 MAPK was determined by Western immunoblotting and apoptotic cells were detected by the terminal deoxynucleotidyl transferase (TdT)-mediated dUDP-biotin nick end labeling (TUNEL).

RESULTS: Intestinal ischemia followed by reperfusion activated p38 MAPK, and the maximal level of activation (7.3-fold vs sham-operated group) was reached 30 min after I/R. Treatment with SB 203580, a p38 MAPK inhibitor, reduced intestinal apoptosis (26.72±3.39% vs 62.50±3.08% in I/R vehicle, P<0.01) and decreased plasma D-lactate level (0.78±0.15 mmol/L in I/R vehicle vs 0.42±0.17 mmol/L in SB-treated group) and improved post-ischemic intestinal histological damage.

CONCLUSION: p38 MAPK plays a crucial role in the signal transduction pathway mediating post-ischemic intestinal apoptosis, and inhibition of p38 MAPK may attenuate ischemia-reperfusion injury.

Morphological and distribution characteristics of sweat glands in hypertrophic scar and their possible effects on sweat gland regeneration

BACKGROUND

In hypertrophic scar tissue, no sweet gland and hair follicle exist usually because of the dermal and epidermal damage in extensive thermal skin injury, thus imparing regulation of body temperature. This study was designed to reveal the morphological and distributional characteristics of the sweat glands in normal skin and hypertrophic scar obtained from children and adults, and to study the possible interfering effects of the scar on regeneration of the sweat gland after burn injury.

METHODS

Biopsies of hypertrophic scar were taken from four children (4 - 10 years) and four adults (35 - 51 years). Normal, uninjured full-thickness skin adjacent to the scar of each patient was used as control. Keratin 19 (K19) was used as the marker for epidermal stem cells and secretory portion of the sweat glands, and keratin 14 (K14) for the tube portion, respectively. Immunohistochemical and histological evaluations were performed.

RESULTS

Histological and immunohistochemical staining of skin tissue sections from both the children and adults showed K19 positive cells in the basement membrane of epidermis of normal skin. These cells were seen only single layer and arranged regularly. The secretory or duct portion of the eccrine sweat glands was situated in the dermis and epidermal layer. However, in the scar tissue, K19 positive cells were scant in the basal layer, and the anatomic location of the secretory portion of sweat glands changed. They were located between the border of the scar and reticular layer of the dermis. These secretory portions of sweat glands were expanded and were organized irregularly. But a few K14 positive cells were scattered in the scar tissues in cyclic form.

CONCLUSIONS

There are some residual sweat glands in scar tissues, in which the regeneration process of active sweat glands is present. Possibly the sweat glands could regenerate from adult epidermal stem cells or residual sweat glands in the wound bed after burn injury.

Effects of extrogenous aFGF on bax and bcl-2 expression in intestinal cells after ischemia/reperfusion

AIM: To detect the effects of acid fibroblast growth factor (aFGF) on apoptosis and Bax and bcl-2 expression in rat intestine after I/R injury, and to explore the protective mechanisms of aFGF on intestinal villus.

METHODS: One hundred and eight Wistar rats were randomly divided into 4 groups, namely intestinal ischemia/reperfusion group (R, n = 48), intestinal ischemia group (I, n = 6), aFGF treatment group (A, n = 48) and sham-operated group (C, n = 6). The rats sustained 45 min of arteria mesenterica (SMA) occlusion to establish the ischemia model. At the beginning of reperfusion, rats in group R and A were treated with normal saline (0.15 mL) and aFGF (20 μg/kg, 0.15 mL) respectively. Then each six rats as a sub-group were reperfused for a duration of 0.25, 0.5, 1, 2, 6, 12, 24, 48 h respectively. Cell apoptotic rates in intestinal villus were determined with terminal deoxynucl-eotidy transferase mediated dUTP-biotin nick-end-labeling technique (TUNEL). RT-PCR was used to detect the expressions of bax and bcl-2 gene in intestinal villus. Immunohistochemical methods were adopted to detect bax and bcl-2 protein expressions and distributions.

RESULTS: The improvement of intestinal histological structures was observed at 2 h, 6 h and 12 h after the reperfusion in group A, compared with group R. The apoptotic rates were (41.17±3.49 %), (42.83±5.23 %) and (53.33±6.92 %) at 2, 6, 12 h after reperfusion respectively in group A, and these rates were significantly lower than those in group R (P < 0.05). The expressions of bax gene and bax protein in intestinal villus were gradually increased after ischemia/reperfusion, while the transcription of bcl-2 gene and expression of bcl-2 protein were decreased. During the 2-12 h of reperfusion, the transcription of bcl-2 gene and expression of bcl-2 protein were significantly increased in group A compared with those in group R (P < 0.05). However, the expressions of bax gene and bax protein were significantly higher than those in group R (P < 0.05).

CONCLUSION: Intravenous aFGF could alleviate I/R-induced injury, in which its effects on the facilitation of bcl-2 transcription and inhibition of bax expression may play an important role.

[Enhancing the repair quality of skin injury on porcine after autografting with the bone marrow mesenchymal stem cells]

OBJECTIVE

To explore the effects of bone marrow mesenchymal stem cells (MSCs) on the quality of healing of porcine skin wounds after burn injury so as to provide a new method for clinical skin repair in the future.

METHODS

Seventy-two deep-partial thickness burn wounds were produced on the back of 6 minipigs and then the pigs were randomly divided into 6 groups: saline control, MSCs treatment, MSCs plus basic fibroblast growth factor (bFGF) treatment, MSCs plus epidermal growth factor (EGF) treatment, bFGF treatment or EGF treatment only. MSCs were isolated from porcine marrow and cultured in vitro. After labeling with BrdU, MSCs were autografted onto the skin wounds. 7, 14, 21 and 42 days after the injury, the area of the wounds were measured and the histological examination was performed to evaluate the velocity and quality of wound healing.1, 2 and 4 weeks after transplantation, immunohistochemical examinations were carried out to detect the positive staining of BrdU, cytokeratin and S-100 to evaluate the wound healing quality.

RESULTS

The area of wounds was decreased at day 7 and most of these wounds were healed on day 21 after injury. Although there was no significant statistical difference in the contraction rate among these six groups, however, the reduced wound areas in the MSCs plus bFGF treatment group was 15% to 20% more than that in the other 5 groups. Histological examination and semi-quantitative analysis demonstrated that the number of vessels and the expression density of S-100 in the MSCs plus bFGF treatment wounds were significantly enhanced than that in the other groups.

CONCLUSION

MSCs autografting may benefit to enhance the wound healing quality in porcine skin, which may open a new way to reach a "perfect repair" after skin injury.

[Gene expression of angiogenesis-related factors in fetal skin at different developmental stages and childhood skin]

OBJECTIVE

To explore the change in gene expression of angiogenesis-related factors vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), acid fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF), in fetal skin at different developmental stages and children skin and their potential biological significances.

METHODS

Fetal skin samples of human embryo were obtained from spontaneous abortion at different gestational ages ranging from 13 to 32 weeks, and children skin specimens were collected from child patients (4-12 years) undergoing plastic surgery. After morphological characteristics of skin at different developmental stages were defined histologically gene expressions of VEGF, Ang-1, aFGF and bFGF were examined with reverse transcription-polymerase chain reaction analysis (RT-PCR).

RESULTS

The trend of changes in gene expression of VEGF, Ang-1, aFGF and bFGF was not same for different skin specimens at various developmental stages. In early gestational fetal skin, genes of VEGF and Ang-1 were strongly expressed, while in late gestational and childhood skins, gene expressions of VEGF and Ang-1 were apparently decreased. In skin of middle gestational stage, the level of aFGF gene expression was highest, and then it was progressively reduced. In childhood skin, this gene was weakly expressed. In marked contrast, the contents of transcripts of bFGF showed no substantial change in fetal skin at different developmental stages, whilst the mRNA content of bFGF was significantly decreased in childhood skin.

CONCLUSION

VEGF, Ang-1, aFGF and bFGF might be involved in regulating angiogenesis in skin from fetuses of different gestational stages and children. The relative increase in gene transcription of VEGF and Ang-1 in younger fetal skin might be one of the reasons why cutaneous cells proliferate rapidly and the wounds heal without scar.

Activation of phosphorylating-p38 mitogen-activated protein kinase and its relationship with localization of intestinal stem cells in rats after ischemia-reperfusion injury

AIM: To investigate the expression of phosphorylating p38 mitogen-activated protein kinase (MAPK) in rat small intestine after ischemia-reperfusion (I/R) insult and its relationship with the localization of intestinal stem cells.

METHODS: Forty-eight Wistar rats were divided randomly into three groups, namely intestinal ischemia-reperfusion group (R), intestinal ischemia group (I) and sham-operated control group (C). In group I, the animals were killed 45 minutes after superior mesenteric artery (SMA) occlusion, while in group R the rats sustained SMA occlusion for 45 minutes and reperfusion for 2, 6, 12 or 24 h respectively. In sham-operated control group, SMA was separated, but without occlusion. The activity of plasma diamine oxidase (DAO) was determined. Intestinal tissue samples were also taken for histological analysis and immunohistochemical analysis of MAPK p38 detection and intestinal stem cell localization.

RESULTS: The changes in histological structure and plasma DAO levels indicated that the intestinal barrier was damaged after intestinal I/R injury. In group C and I, each crypt contained 5-6 p38 MAPK positive cells, which were mainly located in the lower region of the crypts. This was consistent with the distribution of intestinal stem cells. The presence of positive cells in crypts increased with the time of reperfusion and reached its peak at 12 h after reperfusion (35.6%).

CONCLUSION: After intestinal I/R injury, the expression of phosphorylating-p38 MAPK in small intestine increased with the duration of reperfusion, and its distribution coincided with that of intestinal stem cells and their daughter cells, indicating that phosphorylating-p38 might be a possible marker of intestinal stem cells.

Rapid mitogen-activated protein kinase by basic fibroblast growth factor in rat intestine after ischemia/reperfusion injury

AIM: Previous studies showed that exogenous basic fibroblast growth factor (bFGF or FGF-2) could improve physiological dysfunction after intestinal ischemia/reperfusion (I/R) injury. However, the mechanisms of this protective effect of bFGF are still unclear. The present study was to detect the effect of bFGF on the activities of mitogen-activated protein kinase (MAPK) signaling pathway in rat intestine after I/R injury, and to investigate the protective mechanisms of bFGF on intestinal ischemia injury.

METHODS: Rat intestinal I/R injury was produced by clamping the superior mesenteric artery (SMA) for 45 min and followed by reperfusion for 48 h. Seventy-eight Wistar rats were used and divided randomly into sham-operated group (A), normal saline control group (B), bFGF antibody pre-treated group (C), and bFGF treated group (D). In group A, SMA was separated without occlusion. In groups B, C and D, SMA was separated and occluded for 45 min, then, released for reperfusion for 48 h. After the animals were sacrificed, blood and tissue samples were taken from the intestine 45 min after ischemia in group A and 2, 6, 24, and 48 h after reperfusion in the other groups. Phosphorylated forms of p42/p44 MAPK, p38 MAPK and stress activated protein kinase/C-Jun N-terminal kinase (SAPK/JNK) were measured by immunohistochemistry. Plasma levels of D-lactate were examined and histological changes were observed under the light microscope.

RESULTS: Intestinal I/R injury induced the expression of p42/p44 MAPK, p38 MAPK, and SAPK/JNK pathways and exogenous bFGF stimulated the early activation of p42/p44 MAPK and p38 MAPK pathways. The expression of phosphorylated forms of p42/p44 MAPK was primarily localized in the nuclei of crypt cells and in the cytoplasm and nuclei of villus cells. The positive expression of p38 MAPK was localized mainly in the nuclei of crypt cells, very few in villus cells. The activities of p42/p44 MAPK and p38 MAPK peaked 6 h after reperfusion in groups B and C, while SAPK/JNK peaked 24 h after reperfusion. The activities of p42/p44 MAPK and p38 MAPK peaked 2 h after reperfusion in group D and those of SAPK/JNK were not changed in group B. D-lactate levels and HE staining showed that the intestinal barrier was damaged severely 6 h after reperfusion; however, histological structures were much improved 48 h after reperfusion in group D than in the other groups.

CONCLUSION: The results indicate that intestinal I/R injury stimulates the activities of MAPK pathways, and that p42/p44 MAPK and p38MAPK activities are necessary for the protective effect of exogenous bFGF on intestinal I/R injury. The protective effect of bFGF on intestinal dysfunction may be mediated by the early activation of p42/p44 MAPK and p38 MAPK signaling pathways.

[An experimental study on the differentiation of bone marrow mesenchymal stem cells into vascular endothelial cells]

OBJECTIVE

To investigate the feasibility of differentiation of bone marrow mesenchymal stem cells (MSCs) into vascular endothelial cells and the mechanism of its involvement in wound healing.

METHODS

Porcine MSCs were harvested from porcine marrow, and they were isolated and purified by density gradient centrifugation. After being cultured and amplified in vitro, the MSCs were labelled with BrdU (5-bromodeoxy-uridine). Full skin loss wound was created on the back of the mini-swine whose bone marrow was obtained. The labelled MSCs with fibrin glue as the vector were regrafted back to the donor animal wound. The wound tissue specimens were harvested at 2, 4, 6, 8 and 12 post-operation weeks and were immunohistochemically stained by BrdU and factor VIII (FVIII) for comparative study.

RESULTS

Most BrdU positive cells aggregated around small blood vessels in the granulation tissue of the wounds. Only individual vascular endothelial cells were BrdU positive. There was FVIII expression in the cytoplasm of BrdU positive cells.

CONCLUSION

MSCs were closely correlated with the formation of small blood vessels in granulation tissue during wound healing process. The porcine MSCs possessed the potential to differentiate into vascular entoehelial cells and to participate in wound healing under the micro-enviroment of the wound.

[Study on the location and the expression characteristics of epidermal stem cells in normal adult skin and scar tissue]

OBJECTIVE

To investigate the different location and the expression characteristics of epidermal stem cells in normal adult skin and scar tissue.

METHODS

Skin tissue specimens were harvested from the corresponding sites from 6 healthy volunteers and from scar tissue of 6 patients 1 year after major deep burn. beta1 integrin and keratin 19 (K19) were employed as the biochemical markers for stem cells and transit amplifying cells identification and keratin 14 (K14) and keratin 10 (K10) as markers for post-mitotic cells and terminally differentiated cells respectively. Integrin and keratin were determined by Elivision two-step immunohistochemistry.

RESULTS

The expression of beta1 integrin and the K19 positive cell count in the epithelial basal layers of scar tissue were evidently decreased and weakened than those in normal adult healthy skin. Furthermore, the positive cells expressing K14 in epidermis of scar tissue were only located in 2 - 3 layers of basal epidermis, and their number was much less than that in normal adult skin. Whereas the cells positively expressing K10 were distributed wider in area than that in normal healthy skin. The epidermal stem cells and transit amplifying cells in scar epidermis were much less in number than that in normal skin. The differentiation process of scar epidermal stem cells was different from that of normal skin. And the proportions of post-mitotic cells and terminally differentiated cells were abnormal.

CONCLUSION

The results indicated that the self-renewal ability of the scar epidermis was decreased, and the differentiation process of it was in disorder, which may be a reason for the abnormality of structure and function of the epidermis in scar, and a reason for the decreased ability of wound healing of scar tissue.

[The expression characteristics and their biological significance of epidermal growth factor and basic fibroblast growth factor in rat skins at different development stages]

OBJECTIVE

To explore the localization and expression characteristics of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) in rat skins at different development stages (embryonic, newborn, adult).

METHODS

Skins from embryonic, newborn and adult rats were taken, and detected by immunohistochemical technique.

RESULTS

Positive immunohistochemical signal of EGF could be found in skins from embryonic, newborn and adult rats, mainly in the cytoplasm of the epidermal cells, fibroblasts, hair follicle epithelial cells, and endothelial cells. With the increase in age, the expression amount of EGF was increased. The positive signal of bFGF could be found in skins of newborn and adult rats, while the signal of bFGF in skin of embryonic rats was negative.

CONCLUSION

The results indicate that endogenous EGF plays important role in epidermal development in embryonic stage and wound healing in adult after injury. The negative expression of bFGF in skin of embryonic rat indicate that the absence of bFGF may be one of the reasons for the non-scar healing in embryonic stage.

The involvement of multiple protease-antiprotease systems and gut origin sepsis in zymosan-associated endothelial barrier injury and multiple organ dysfunction in rats

Multiple organ dysfunction syndrome is a dominant cause of mortality in the intensive care unit. Experimentally, a condition similar to the multiple organ dysfunction syndrome can be induced by the intraperitoneal injection of sterile zymosan. In the present study we investigate potential alterations in multiple organ functions, endothelial permeability, and antiproteinases after intraperitoneal injection of zymosan at various doses. Zymosan-induced generalized inflammation lead to endothelial barrier injury in multiple organs/tissues, a decrease in systemic arterial pressure, impaired organ function and gut defence function, and consumption of protease inhibitors, particularly the consumption of alpha2 antiplasmin. Endothelial barrier injury appears to present a dose- and organ-dependent pattern in multiple organs/tissues, and the increase in endothelial barrier permeability occurred prior to organ dysfunction. Zymosan induced the development of multiple organ dysfunction syndrome, probably initiating multiple protease-antiprotease systems, particularly the fibrinolytic system, leading to endothelial barrier injury, tissue edema, parenchymal cell damage, and eventual organ dysfunction, potentially augmented by a secondary bacterial infection.

[The stimulating effects of bFGF on fibroblast function and its C-fos gene expression]

OBJECTIVE

To study the stimulating effects of basic fibroblast growth factor(bFGF) on fibroblast function and its ability to expression of c-fos gene. Furthermore, to explore the possible network action between bFGF and oncogene in modulating wound healing.

METHODS

Cultured rat fibroblasts were divided into bFGF stimulating group and control group. Fibroblasts in bFGF stimulating group were treated with bFGF in a dosage of 40 ng/culture hole, while the control fibroblasts were treated with the same vehicle without bFGF. The morphology, cell vitality and their ability to express c-fos gene in the fibroblasts in both groups were studied with MTT and immunohistochemical methods.

RESULTS

All fibroblasts in bFGF treated groups were enlarged and showed increased vitality with MTT method. C-fos gene expression in bFGF stimulating group was increased, especially in nucleus when compared with those in control group.

CONCLUSION

The results show that the function and the ability to express c-fos gene in bFGF treated fibroblasts are enhanced. Combined with our previous studies, it may make a conclusion that there is a network regulation mechanism between growth factors and some oncogenes.

[Characteristics of bFGF and TGF-beta expression in dermal chronic ulcers and hypertrophic scars and their effects on tissue repair]

OBJECTIVE

To localize the distribution of basic fibroblast growth factor (bFGF) and transforming growth factor-beta(TGF-beta) in tissues from dermal chronic ulcer and hypertrophic scar and to explore their effects on tissue repair.

METHODS

Twenty-one cases were detected to localize the distribution of bFGF and TGF-beta, among them, there were 8 cases with dermal chronic ulcers, 8 cases with hypertrophic scars, and 5 cases of normal skin.

RESULTS

Positive signal of bFGF and TGF-beta could be found in normal skin, mainly in the keratinocytes. In dermal chronic ulcers, positive signal of bFGF and TGF-beta could be found in granulation tissues. bFGF was localized mainly in fibroblasts cells and endothelial cells and TGF-beta mainly in inflammatory cells. In hypertrophic scar, the localization and signal density of bFGF was similar with those in granulation tissues, but the staining of TGF-beta was negative.

CONCLUSION

The different distribution of bFGF and TGF-beta in dermal chronic ulcer and hypertrophic scar may be the reason of different results of tissue repair. The pathogenesis of wound healing delay in a condition of high concentration of growth factors may come from the binding disorder of growth factors and their receptors. bFGF may be involved in all process of formation of hypertrophic scar, but TGF-beta may only play roles in the early stage.

Effect of intestinal ischemia-reperfusion on expressions of endogenous basic fibroblast growth factor and transforming growth factor β in lung and its relation with lung repair

AIM: To study the changes of endogenous transforming growth factor β (TGF-β) and basic fibroblast growth factor (bFGF) in lung following intestinal ischemia and reperfusion injury and their effects on lung injury and repair.

METHODS: Sixty Wistar rats were divided into five groups, which underwent sham-operation, ischemia (45 min), and reperfusion (6, 24 and 48 h, respectively) after ischemia (45 min). Immunohistochemical method was used to observe the localization and amounts of both growth factors.

RESULTS: Positive signals of both growth factors could be found in normal lung, mainly in alveolar cells and endothelial cells of vein. After ischemia and reperfusion insult, expressions of both growth factors were increased and their amounts at 6 h were larger than those of normal control or of 24 and 48 h after insult.

CONCLUSION: The endogenous bFGF and TGF-βexpression appears to be up-regulated in the lung following intestinal ischemia and reperfusion, suggesting that both growth factors may be involved in the process of lung injury and repair.

[Transforming growth factor beta 1 and interleukin 6 mRNA expression in wound tissues of patients with diabetic ulcers]

OBJECTIVE

To study the relationship between the changes of mRNA expression in wound tissues of diabetic ulcers and tissue repair.

METHODS

The mRNA expression of TGF-beta 1 and IL-6 in eight bioptic samples of diabetic ulcers were detected by RT-PCR and pathologic methods, and the surrounding normal skins from the same patients were measured as control group.

RESULTS

The mRNA expression levels of TGF-beta 1 were markedly decreased in the diabetic ulcers compared with control group, while the mRNA expression levels of IL-6 were increased at the same reaction conditions.

CONCLUSION

The different changes of mRNA expression level of TGF-beta 1 and IL-6 in wound tissue result in low production and decreased activity of TGF-beta 1 and IL-6, which lower the reparative ability of wound tissue.

[Comparative study of epidermal growth factor and basic fibroblast growth factor on wound healing]

OBJECTIVE

The biological effects of recombinant human epidermal growth factor (rhEGF) and recombinant human fibroblast growth factor (rhFGF) were evaluated on the model of incised wounds in mini pigs.

METHODS

Total of 160 incised wounds in 16 mini pigs were divided into two groups (rhEGF group and rhFGF group), each containing 80 wounds. In rhEGF group, 60 incised wounds were treated with different dosages of rhEGF (50, 10 and 0.5 micrograms/wound), and another 20 wounds were treated with solvent as control group. In rhFGF group, all wounds were treated in the same way as described in rhEGF group, the dosages of rhFGF were 150, 90 and 30 U/cm2 respectively. The measurements of cavity volume and area in wound, histological examination were used to evaluate the results of wound healing.

RESULTS

The results showed that wound healing was accelerated in all wounds treated with rhEGF and rhFGF. In rhEGF group, the velocity of re-epithelialization was faster than that of rhFGF group, however, new granulation tissue in rhFGF was more than that of rhEGF group.

CONCLUSION

The results indicate that rhEGF and rhFGF can stimulate wound healing, however, the mechanisms and the biological effects involved in these processes are quite different. It suggests that it is better to use rhFGF in those wounds which need more granulation tissue formation and use rhEGF in the wounds which mainly need re-epithelialization.