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Objective To isolate the dedifferentiation-derived epidermal stem cells (DDESCs)to further investigate their phenotypic characteristics. Methods The sheets of human foreskin were digested overnight after removal of adipose tissues and then the epidermis was separated from the dermis.The epidermis sheets which eliminated basal stem cells by repeated adhesion to type Ⅳ collagen and flushing were transplanted onto the full-thickness skin wounds on the back of BALB/c nude mice. After five days, the sheets were collected and digested into single cells, after which the percentages of positive cells of CK10, CK19 and β1 integrin were detected by flow cytometric analysis. DDESCs were isolated by rapid adhesion to type Ⅳ collagen. The expressions of CK19, β1 integrin, Oct4 and Nanog in the cells were examined using immunofluorescence and quantitative real-time polymerase chain reaction (RTPCR). Results The percentages of positive cells of CK19 and 31 integrin were increased (P ＜0.01 )and those of CK10 in the transplanted sheets decreased ( P ＜0.01 ) five days after transplantation. Isolation of DDESCs by repeated adhesion to type Ⅳ collagen showed 4.56% adhering cells in the transplantation group within 10 minutes. The in vitro phenotypic assays showed that the expressions of CK19, β1 integrin, Oct4 and Nanog in DDESCs were similar to those of original epidermal stem cells ( P ＞0.05 ) but remarkably higher than those in the control group ( P ＜ 0.01 ). Conclusion The phenotypic characteristics of DDESCs cultured in vitro are similar to those of epidermal stem cells, indicating a new approach for wound repair and regeneration.
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Objective To investigate the correlation between human epidermal stem cell (hESCs) and hypertrophic scar or keloid. Methods Improved collagen Ⅳ-coated adhesion methods was used to isolate and culture the epidermal stem cells after neutral protease selectively digested the dermo-epidermal junctions. After the cells were cultured and expanded in vitro, and passage 3 hESCs were induced by different concentrations of TGF-β1 (0.1, 5.0, and 10.0 ng/ml). Morphological fea-tures and identification of these cells were meseasured by HE, Masson, immunohistochemical staining on the days 3 and 7, respectively. Results After induced by TGF-β1 for 3 and 7 days, the morpholo-gy of the epidermal stem cell (hESCs) was changed into fusiform shape, similar to fibroblasts. 70 % ofthe cell which was induced by TGF-β1 were blue stained in the cytoplasm by Masson stain, which is the distinctive method for collagen, suggesting collagen appeared or increased in the cells. The collagen concentrations in supernatants of hESCs were 0.4150±0.0014, 0.3380±0. 0020, and 0.3870±0.0020, much higher than that in control group (0.0780±0.0025) and normal skin fibro-blast group (0.15004±0.0051) (P<0.05). Immunohistochemical staining revealed that positive rates of these cells for anti-vimentin staining were more than (95.00±1.20)% in experiments and (5.70±0.20)% in control group. Conclusion The differentiantion of hESCs induced by TGF-β1 into fibro-blasts indicates that hESCs may play a role in the pathogenesis of hypetrophic scar and keloid.
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Objective To investigate the inductive role of traumatic microenvironment in dedifferentiation of epidermal cells and explore the potential role of Wnt signaling pathway in this biological process. Methods The sheets of human foreskin were digested overnight after removal of adipose tissue, and then the epidermis was separated from the dermis. The separated epidermis sheets were repeatedly adhered to type Ⅳ collagen and flushed to remove the epidermal stem cells. The obtained epidermis sheets were transplanted onto the full-thickness skin wounds on the back of BALB/c nude mice, five days after which the cell lineage was evaluated by immunohistochemistry and the expressions of Wnts and downstream components in the grafted epidermal sheets examined by RT-PCR and Western blot. Results The cells in the basal layer of full-thickness epidermal sheets were positive for CK19 and β1 integrin and negative for CK10. While the cells in uhrathin epidermal sheets treated with type Ⅳ collagen were fully positive for CK10. Five days after transplantation of the ultrathin epidermal sheets, cells negative for CK10 but positive for CK19 and β1 integrin emerged at the wound-neighboring side of the skin grafts. At the same time, the expressions of Wnt-10b, Wnt-4 and Wnt-7a mRNA were increased by about 3.1-fold, 2.2-fold and 1.4-fold independently after transplantation. Furthermore, the expressions of β-catenin and β-catenin target genes (cyclin D1 and c-myc) were elevated by about 3-fold, 1.5-fold and 2-fold respectively in the grafted epidermal sheets (P < 0.01). Conclusion Traumatic microenvironment can induce epidermal cell dedifferentiation, when the Wnt/β -catenin signaling pathway may play an important role.
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Objective To explore the effect of botulinum toxin type A(BTXA)in the treatment of early hypertrophic scars(HTS).Methods BTXA was injected into and around the eady HTS,and then the modal and histological changes of the scars as well as the clinical reaction were observed in the patient.BTXA was also injected into muscle around the incision and effect on the cicatrization observed.Results Injection of BTXA could obviously alleviate ache and pruritus of eady HTS and could impel the atrophy and inteneration of eady HTS.Changes were found in paraffin-embedded tissue section by the hemetoxylin and eosin(HE)staining.Injection of BTXA into muscle around the cut could can reduce occurrence of HTS.Conclusion BTXA can help prevent the early HTS to a certain extent.The mechanism underlying this effect may be related to the reducing the tension around scars and proliferative activity,interfering with the signal transduction of small nerves,affecting the proliferation and apoptosis of fibroblasts and subsequently decreasing the collagen synthesis.
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Objective To investigated the distribution of epidermal stem cells in rat full-thickness wound tissues during the wound healing process and to elucidate the roles of epidermal stem cells in wound repair in vivo. Methods Eighty circular full-thickness wounds were produced on both sides of the back in 20 male Wistar rats labeled with BrdU 60 days previously (4 wounds in each rat). BrdU, β1 integrin and keratin 19 (K19) were employed to determine the epidermal stem cells with SP immunohistochemical methods, and the epithelialization was determined with routine histological methods of HE staining on the 3rd, 7th, 14th, and 21st days after operation. Results No cells with positive immunostaining for β1 integrin, K19 and BrdU were found in granulation tissue of wound in both groups during the healing process. However, a few scattered β1 integrin and K19 positive cells were found within the stratum spinosum and stratum granulosum of the epidermis on the wound edges on the 3rd day post-injury. And these positive cells gradually became more and more in number, and mostly concentrated on the border of wound edges till the wounds healed. In addition, the number of positive cells for β1 integrin and K19 in the infected wounds was less than that in non-infected wounds. These positive cells for β1 integrin and K19 staining on the wound edge were also positively stained with BrdU in the cellular nuclei. Conclusion The above results indicate that ectopia of epidermal stem cells present a major function during wound epithelialization.
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Objective To investigate the possible signaling mechanisms by which recombinant human platelet-derived growth factor (rhPDGF) accelerated healing of cutaneous wound in diabetic rats. Methods Four full-thickness skin wounds were incised in the back of 26 male Wistar diabetic rats. The wounded rats were divided into 3 groups (7 or 8 rats each group). One group without treatment was used as a control, and the other 2 groups were treated with rhPDGF at a dose of 7.0 μg/cm2 wound or vehicle ( DMSO/0.9%NaCl, vol/vol 1:1) from 1 to 14 days. The wound healing was evaluated by the measurements of the wound volume and area. Immunofluorescent and immunohistochemical staining were used to examine the phosphorylation of extracellular signal-regulated kinase 1/2(ERK1/2) and the expression of proliferative cell nuclear antigen (PCNA), respectively. Results Granulation tissue appeared in the bed of wound after injury. The number of blood capillary buds and fibroblasts was greater in the rhPDGF-treated group than that in the other 2 groups. A lot of inflammatory cells infiltration and collagen deposition were observed in the wound. The wound-volume in the rhPDGF-treated group was smaller than that in control group ( P ＜ 0.05). The reepithelialization rate in rhPDGF-treated group was higher than that in the other 2 groups at 7 days after injury ( P ＜ 0.05). The expression of PCNA in reparative cells was higher in rhPDGF-treated group than in control group or vehicle-treated group at 3,7 days after injury( P ＜ 0.05). The phosphorylation of ERK1/2 was stronger in rhPDGF-treated group than that in control group or vehicle group at 7 and 14 days after injury( P ＜ 0.05). Conclusion These results suggest that rhPDGF accelerates wound healing and improves healing quality by increasing the phosphorylation of ERK1/2.
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To observe and assess the performance and effect of our self-made FD-1 freezing drier on biomaterials. R502 compressor and R502 refrigerating agent were adopted. In the experiment, FD-1 lyophilized collagen sponge, strain and defibrinogenase. The evaporating-condenser temperature reached -45 degrees C and the small icebox temperature reached -30 degrees C under the loading or free-loading circumstances in the lyophilizing box. The lyophilized collagen sponge had many pores in the structure, and the strain and the defibrinogenase were lyophilized and maintained satisfactorily. This freezing drier is suitable for lyophilizing some biomaterial samples in small or medium batches.
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Humans , Bacteria , Collagen , Freeze Drying , Methods , TemperatureABSTRACT
Objective To investigate the dedifferentiation of epidermal cells into their progenitor stem cells induced by basic fibroblasts growth factors(bFGF) in vitro.Methods HEKa cells obtained from Cascade were found flattening and formation of cell-to-cell contacts after 6 to 7 passages,which resembled differentiated epidermal cells in vivo.To examine the effect of growth factors on the cell proliferative alterations,bFGF(100 ng/ml) was added into the culture medium for different periods(6,12,24,48,or 72 h),then the cell proliferation was measured by MTT assay.Phenotypic changes and the cell-fate determination of HEKa cells after bFGF treatment were detected by immunocytochemical assays,flow cytometry and RT-PCR analysis.HEK cells with no intervention treatment were used as a control.Results MTT assay proved that the optimal culture condition to induce the dedifferentiation of epidermal cells into their progenitors was to culture HEKa cells for 36 to 48 h when the addition of bFGF was 100 ng/ml.After treatment with bFGF for 48 h,clusters of round-shaped cells appeared around differentiated epidermal cells,and expanded progressively thereafter.These cells were smaller in shape and with larger nuclear/cytoplasm ratio,and had not only clonogenicity but also ability to form a cutaneous ridge-like structure.Immunohistochemical staining revealed that the expression levels of ?1 integrin,CK19 and CK14 were up-regulated,while the expression of CK10 was significant down-regulated after bFGF treatment.Flow cytometry indicated that there were more CK19-positive and CK14-positive cells in the treatment group than in the control(74.77% vs 15.74%,and 87.14% vs 67.26%respectively),but much lesser CK10-positive cells(4.56% vs 98.56%).Additionally,the mRNA expression levels of ?1 integrin,CK19 and CK14 were up-regulated after bFGF treatment,but that of CK10 was down-regulated.Conclusion bFGF can reverse the differentiated process of epidermal cells and induce them to produce immature,stem-like cells,which can proliferate and be used in the wound repair and regeneration of skin tissues.
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<p><b>OBJECTIVE</b>To describe the methods which were used to develop collagen-based materials for wound dressing.</p><p><b>METHODS</b>Fresh frozen bovine tendon was treated with 0.05 mol/L acetic acid at pH 3.2 for 48-72 hours, homogenized, filtered, mixed with 8% chondroitin sulphate, for creating a deaerated 1.5%-2.5% collagen solution. The solution was lyophilized in either a pre-frozen or non-pre-frozen mould. The collagen sponge was then cross-linked with 0.25% glutaraldehyde for 24 hours. Three other types of wound dressings were developed using a similar method: collagen membrane with a polyurethane membrane onlay, polyurethane-coated collagen membrane and collagen membrane on gauze.</p><p><b>RESULTS</b>It was demonstrated that the use of frozen bovine tendon was stable, and that the prepared collagen sponge contained pores of 50-400 microm in diameter.</p><p><b>CONCLUSIONS</b>Collagen could be used as wound dressing.</p>
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Animals , Cattle , Amino Acids , Biological Dressings , Collagen , Chemistry , Freeze Drying , PolyurethanesABSTRACT
In this study the treatment effect of combined implantation of autologous skin on pig dermis in injured rats was observed. Twenty-one Wistar rats were used, and the wounds were formed by excising a piece of full thickness skin on the back. After the pig dermis was implanted, the autologous skin was grafted on the dermis at 0.7 and 10 days. In the group with perforated pig dermis, the autograft skin was implanted on the day when the pig dermis was implanted. The healing effect was evaluated by measuring wound area, and by observing the growth of the autograft skin. Two weeks after the autograft skin was implanted, the skin securely adhered to the dermis, and the edge of autograft skin expanded clearly. The wound of the autograft skin implanted in the perforation of the dermis healed completely after 3 weeks, but the other 3 groups had remnant small wound. The autograft skin merged with the dermis and its surrounding tissue, but a clear dividing line still existed between autograft skin and dermis after implantation. The area of the implanted dermis and autograft skin varied from 51.8% to 65.9% compared to its original size. The results suggested that the time and the way of autologous skin grafting on xenogenous dermis may influence wound contraction and healing time.
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Animals , Female , Male , Rats , Dermis , Transplantation , Graft Survival , Rats, Wistar , Skin Transplantation , Methods , Swine , Swine, Miniature , Transplantation, Autologous , Transplantation, HeterologousABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression sequence and distribution characteristics of the protooncogenes c-fos, c-myc and endogenous basic fibroblast growth factor (bFGF) genes in burned tissues, and to explore the possible effects of changes in these genes' functions on wound healing.</p><p><b>METHODS</b>Partial-thickness burns of 30% TBSA were established on backs of Wistar rats. In situ hybridization and histological methods were used to detect expression of c-fos, c-myc and bFGF genes in normal and burned tissue at 3 h, 6 h, 1 d, 3 d, 7 d and 14 d postburn.</p><p><b>RESULTS</b>Although expression of c-fos and c-myc genes and bFGF gene could be found in normal skin, the expression of all three were markedly induced by burn wounds and the expression models in sequence and distribution were quite different. Expression of c-fos gene increased and peaked at 6 h. Signals were mainly localized in both nuclei of dermal fibroblasts and monocytes. The expression of bFGF gene increased at 6 h and peaked at 1 d postburn, and was distributed in the cytoplasm of fibroblasts. C-myc gene peaked 3 d postburn and was also distributed in the cytoplasm of fibroblasts.</p><p><b>CONCLUSIONS</b>These results indicated that thermal injury could induce the expression of c-fos, c-myc and bFGF at gene level, showing phasic control and regional distribution. The phasic expression of these genes suggests that there is an interaction between protooncogenes and bFGF, which may play an important role in wound healing. The different expressions of c-fos and c-myc play an inducing role in regulating bFGF, and in turn affect wound healing.</p>
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Animals , Male , Rats , Burns , Metabolism , Fibroblast Growth Factor 2 , Genetics , Gene Expression Regulation , Genes, fos , Genes, myc , In Situ Hybridization , Rats, Wistar , Time FactorsABSTRACT
Objective To investigate the possible signal transduction pathway during the course of recombinant human platelet derived growth factor (rhPDGF) promoting cutaneous incisional wound healing in diabetic rats. Methods Four full thickness skin wounds were incised in the back of 26 Wistar rats with diabetes mellitus that were randomly divided into two groups, Group A (diabetic rats control) and Group B (treated with rhPDGF at 7.0 ?g/cm2 wound). The granulation, collagen sedimentation, the reepithelialization rate of rhPDGF as well as the inflammatory cell filtration were observed 3,7 and 14 days after wound. Immunofluorescence staining was used to observe the expression of ERKs either around the wound and in the wound center and immunohistochemical method applied to observe the changes of c-fos, proliferation cell nuclear antigen (PCNA) and focal adhesion kinase (FAK). Results The histological investigation showed a lot of granule tissues in the bed of wound, a large of inflammatory cells infiltration and collagen deposition, active growth of granule tissues and significant wound contraction. The number of blood capillary buds and fibroblasts in the Group B were more than that in the Group A. The immunohistochemistry showed that the expressions of ERK1 and c-fos increased significantly three days, strengthened seven days and went weak 14 days after rhPDGF application. In the Group B, at every time point, the expressions of PCNA and FAK were more significant than those in the Group A. Conclusions ERK1/2 signal pathway exerts function in rhPDGF accelerating wound healing of rats with diabetes mellitus and plays an important role in proliferation and migration of reparative cells.
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<p><b>OBJECTIVE</b>To explore the expression characteristic of fibronectin gene in hypertrophic scars and diabetic ulcer tissues.</p><p><b>METHODS</b>The biopsies from normal skins, hypertrophic scars and diabetic foot ulcers were taken. The technique of quantitative polymerase chain reaction (PCR) was used to evaluate the gene expression of fibronectin in the above biopsies.</p><p><b>RESULTS</b>Fibronectin gene expression was enhanced in hypertophic scars and decreased in diabetic foot ulcers compared with that in normal skins. Quantitative comparison showed about 2-fold increase of fibronectin mRNA level in hypertrophic scars and about 3-fold decrease of fibronectin mRNA level in diabetic ulcers as compared with that in normal skins.</p><p><b>CONCLUSIONS</b>Fibronectin gene expression is influenced by the tissue environment. Different expression and synthesis of fibronectin may cause different outcomes in wound healing.</p>
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Adolescent , Adult , Aged , Female , Humans , Male , Middle Aged , Cicatrix, Hypertrophic , Metabolism , Diabetic Foot , Metabolism , Fibronectins , Genetics , Gene Expression , RNA, Messenger , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To investigate the characteristics of PCNA expression in hypertrophic scars and chronic ulcers and to discuss its relation to their formation.</p><p><b>METHODS</b>The expressive quantity and sites of PCNA were detected with the immunohistochemical SP method.</p><p><b>RESULTS</b>PCNA was expressed in all samples. The expressive quantity in hypertrophic scars was higher than chronic ulcers(P < 0.01). The expressive sites of all samples were in the nucleus of fibroblasts and capillary endothelial cells.</p><p><b>CONCLUSIONS</b>The expressive quantity of PCNA was more in hypertrophic scars and less n chronic ulcers. The quantitative difference of expression between hypertrophic scars and chronic ulcers may be correlated to their formation.</p>
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Adult , Female , Humans , Male , Cicatrix, Hypertrophic , Metabolism , Pathology , Proliferating Cell Nuclear Antigen , Skin Ulcer , Metabolism , PathologyABSTRACT
<p><b>OBJECTIVE</b>To study the potential signal pathway involved in pathogenesis of hypertrophic scar formation.</p><p><b>METHODS</b>The samples of scar were obtained from patients with burn wound scars 6 - 28 months post-burn, while the samples of normal control skin came from the donor site of the same patients. Immunohistochemistry and light microscopy techniques were used to identify the expression of epidermal growth factor receptor (EGFR) and phosphotyrosine proteins (p-Tyr), as well as the phosphorylation of signal transducer and activator of transcription 3 (Stat3) in both hypertrophic scars (n = 6) and normal skin (n = 6).</p><p><b>RESULTS</b>Significant differences were observed in the p-Tyr and EGFR positive expression keratinocytes both in hypertrophic scars and normal skin. The expression of p-Tyr, EGFR and Stat3 protein was greater in hypertrophic scars than in normal skin. However, there was no significant difference in p-Stat3 expression between scar tissues and normal skin.</p><p><b>CONCLUSION</b>Different tyrosine kinase activity occurs in hypertrophic scars and normal cutaneous tissues. Initially, varied expression of EGFR is due to different ligand stimulations. However, phosphotyrosine protein and Stat3 are subsequently activated through phosphorylation. In scar tissues, although EGFR has an intrinsic tyrosine kinase activity when activated by EGFR correlated ligand, phosphorylation of Stat3 showed no significant changes. Therefore, cellular signal pathways are induced by EGFR, which might play a role in hypertrophic scar pathogenesis.</p>
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Adult , Female , Humans , Male , Cicatrix, Hypertrophic , Metabolism , DNA-Binding Proteins , Immunohistochemistry , Phosphorylation , Phosphotyrosine , ErbB Receptors , STAT3 Transcription Factor , Skin , Chemistry , Trans-Activators , Wound HealingABSTRACT
<p><b>OBJECTIVE</b>To explore the regulatory mechanisms of transforming growth factor-beta1 (TGF-beta1) and two transcriptional factors Smad 2, 3 on hypertrophic scar formation and fetal scarless healing.</p><p><b>METHODS</b>Thirty-two cases were detected to compare the gene expression of TGF-beta1, Smad 2 and Smad 3 with RT-PCR. Among those cases, there were 8 cases of hypertrophic scars, 8 cases of control skins, 8 cases of fetal skins and 8 cases of adult skins.</p><p><b>RESULTS</b>TGF-beta1, Smad 2 and Smad 3 gene expression could all be detected in hypertrophic scars, fetal and adult skins. Among 8 groups examinated in this experiment (each group comprised a hypertrophic scar and its corresponding normal skin), there were 5, 8 and 5 groups in which TGF-beta1, Smad 2 and Smad 3 gene expression were higher in hypertrophic scars than in normal skins respectively. The fetal skins showed significantly lower level of TGF-beta1 and Smad 3 gene expression compared with adult skins (t = 2.204, P < 0.05 and t = 4.269, P < 0.01 respectively), while mRNA contents of Smad 2 were obviously higher in fetal skins than in adult skins (t = 6.685, P < 0.01).</p><p><b>CONCLUSION</b>TGF-beta1 and its downstream signal molecules Smad 2, Smad 3 might be involved in hypertrophic scar formation. Higher gene expression of TGF-beta1, Smad 2 and Smad 3 in hypertrophic scars might lead to stimulating extracellular matrix deposition, inducing fibroblast proliferation and accelerating fibrogenesis. Lower mRNA contents of TGF-beta1 and Smad 3 in fetal skins compared with adult skins might be associated with fetal scarless healing.</p>
Subject(s)
Cicatrix, Hypertrophic , Metabolism , DNA-Binding Proteins , Genetics , Gene Expression Regulation , Reverse Transcriptase Polymerase Chain Reaction , Skin , Metabolism , Smad2 Protein , Smad3 Protein , Trans-Activators , Genetics , Transforming Growth Factor beta , Genetics , Transforming Growth Factor beta1ABSTRACT
The purpose of this study was to investigate the localization and expression characteristics of phosphorylated form of extracellular-signal regulated-protein kinasel/2 (p-ERKl/2), Ras and C-fos in skin at different development stages and to explore their potential biological significance. Immunohistochemistry and pathological methods were used to detect the expression intensity and distribution of p-ERKl/2, Ras and C-fos in skin of 8 fetuses with different gestational ages (13 to 31 weeks) and 8 adults. Positive immunohistochemical signals of p-ERK1/2, Ras and C-fos. could be found in fetal and postnatal skins. Along with the increment in gestational age, the positive cell rates of p-ERK1/2, Ras and C-fos in the skin elevated progressively. In skins derived from the fetus of late-trimester pregnancy and adult, the positive rates of these three proteins were significantly increased in comparison with skin from the early-trimester fetus (P
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To investigate the expression characteristics of fibroblast growth factor 10 (FGF10) and its receptor (Bek) underlying their effect on the formation of fetal skin appendages (SA). Expressions of FGF10, Bek, cytokeratin (CK19), Bcl-2 and proliferating cell nuclear antigen (PCNA) were detected with pathological and immunohistochemistry techniques in 130 skin specimens, which were obtained from 5 different sites (head, lower jaw, ear lobe, shoulder and presternal region) of 26 fetuses at different embryonic ages (E 8～31weeks). Results showed that FGF10, PCNA and Bcl-2 were over-expressed in interstitial cells distributed in clumps under the epidermis, and all proteins were strongly expressed in epidermal cells and pericytes at E 11weeks. In E 13weeks fetal skin, epidermal cells formed SA anlage through focal proliferation; then they developed, differentiated and migrated towards the dermis. In the skin of E 11～13weeks fetus, the expression of FGF-10, PCNA and Bcl-2 in interstitial cells in the dermis, and the expression of FGF10, Bek, PCNA, CK19, and Bcl-2 proteins in the epithelial cells in SA showed the expression characteristics of these proteins which were in accordance with growth and development of fetal SA. The results suggested that the specific binding of FGF10 from interstitial cells with Bek on the membrane of epithelial cells was the important signal to induce the proliferation and morphogenesis of embryonic SA epithelial \{cells.\ \ \ \}
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To study the location and expression characteristics of epidermal stem cells in normal skin and scar epidermis of children, and to explore the relationship between the differences of these two epidermal stem cells and wound healing after burn. ?1 integrin and keratin 19 (K19) were used as the biochemical markers to identify stem cells and transit amplifying cell, keratin 14 (K14) and keratin 10 (K10) were used as the markers for post-mitotic cells and terminally-differentiated cells, respectively. Normal skin and scar tissue were obtained from children of 4 to 12 years of age. Elivision two-step immunohistochemistry was used. The results showed that in the immunostained tissue sections, the positive ?1 integrin and K19 expression cells were observed in 2～3 layers above the basal layer, whereas K10 expression cells were observed in all epidermal cells except basal cell layer in the scar tissue. Observations revealed that the number of stem cells and transit amplifying cells were less in the scar tissue than that in the normal skin, the differentiation process of scar epidermal stem cells was different from that of normal skin, and the proportion between post-mitotic cells and terminally-differentiated cells was abnormal. The results indicated that the self-renewal ability of the scar epidermis was lowered, and the differentiation process of it was deranged, and this might be considered to be a reason of abnormality of structure and function of the epidermis of scar tissue, and its poorer ability in wound healing.
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AIM: To explore the localization and expression of transfo rming grow th factor-? 1,2 (TGF-? 1,2 ) and alpha-smooth muscle actin (?- ASMA) in fetal a nd adult skins. METHODS: Skins of 15 cases of fetuses with different gestational ages and 5 cases of adults were taken, embedded with paraffin wax, and sectione d. Immunohistochemistry method and pathological method were used to detect the e xpression intensity and distribution of TGF-? 1,2 and ?-ASMA. RESULTS: Positive immunohistochemical signals of TGF-? 1,2 and ?-A SMA were found in fetal and adult skins. In skins derived from young fet us, the positive signals of these three proteins were very weak. Along with the incr ement in gestational age, the positive cellular rates of TGF-? 1,2 and ?- ASMA were elevated pro gressively. In elder fetal and adult skins, TGF-? 1,2 were mostly distributed i n epidermal cells, endothelial cells and some fibroblasts, while ?-ASMA was mainly located in myofibroblasts and sweat gland epithelial cells. CONCLUSION: The endo genous TGF-? 1,2 might be involved in the cutaneous development at embryoni c stage, in the cutaneous structure maintenance at adult stage, and in the wound healing af ter injury.