Wounds on fetal skin can be repaired without leaving scars until the second trimester, but after this period, skin wounds leave scars as in adults. It's known that certain growth factors such as TGF-beta, and bFGF are present at a very low levels during wound repair in fetal skin. These low levels of growth factors minimize inflammatory response and fibroblast proliferation at the wound site, which in turn inhibit collagen synthesis, and thus, allows scarless wound healing. Recently bone morphogenetic proteins (BMPs), one of the TGF-beta superfamily members, have been studied in the wound healing process. According to several studies, BMPs are related to the differentiation and growth of epithelial and mesenchymal cells, but the precise functions of BMPs and of BMP receptors on skin wound healing have not been elucidated. In this study, we investigated the expression pattern of BMP receptors in fetal skin during the second trimester and in adult skin by immunohistochemical staining and RT-PCR. BMP receptors were detected on the suprabasal epithelial cells and in the hair follicles in adult skin, but were not defected in the fetal skin except for the hair follicles. This was confirmed by confirming mRNA levels of BMP receptors by RT-PCR in both adult and fetal skins. In conclusion, BMPs and BMP receptors seem to be related to fetal and adult wound healing, and low levels of BMPs and BMP receptors during the second trimester seem to contribute to scarless wound healing in the fetus, as is TGF-beta during the second trimester.
Fetus/metabolism ; Human ; Immunohistochemistry ; Receptors, Cell Surface/*metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Skin/*embryology/*metabolism

OBJECTIVETo investigate whether the suppression of Wnt10b by siRNA could prevent the development of hair follicle in the cultured rat embryonic skin.

METHODSsiRNA-Wnt10b was synthesized by chemosynthesis method. The dorsal skin of SD rat at embryos were cultured in DMEM in the presence of different percentage of interfering RNA targeting Wnt10b. Wnt10b/beta-catenin expression was analyzed by real-time PCR everyday and by Western blot on the third day. The cultured embryonic skin underwent paraffin embedding, section, HE staining on the third day,in which the number of de novo hair follicle was calculated and statistically analyzed.

RESULTSWnt10b gene in the cultured embryonic skin could be knocked down with the siRNA-based method. Beta-catenin mRNA was not greatly influenced by the downregulation of Wnt10b mRNA. The number of de novo hair follicle placode in cultured embryonic skin decreased, along with the downregulation of Wnt10b and beta-catenin proteins expression.

CONCLUSIONSThe downregulation of Wnt10b mRNA and protein by siRNA reduces the number of de novo hair follicle placode in the cultured rat embryonic skin. Wnt10b may control cytoplasm beta-catenin concentration at the protein level.

Animals ; Hair Follicle ; embryology ; metabolism ; RNA, Messenger ; genetics ; RNA, Small Interfering ; genetics ; Rats ; Skin ; embryology ; metabolism ; Tissue Culture Techniques ; Wnt Proteins ; genetics ; metabolism ; beta Catenin ; metabolism

OBJECTIVETo observe the expression of lefty in adult normal skin (ANS), human embryonic skin (HES) and hyperplastic scar (HS), and to explore the effect of lefty on HS and the relationship between lefty and scarless wound healing in embryo.

METHODSSamples of ANS, HES and HS were collected for frozen section for immunofluorescence staining. The morphology of fibroblast and the expression of the lefty were observed by laser confocal microscopy, and the positive cell rates were calculated.

RESULTSFibroblasts in ANS and HS were long and fusiform with regularity, their nuclei were fusiform or stellate and irregular. Fibroblasts in HES were fusiform, while nuclei were elliptic or fusiform and regular. Positive cell rates of lefty protein in HS (15.38%) were lower than that in NS (67.92%) and FS (81.67%, P < 0.01), and it was lower in ANS compared with HES (P <0.05).

CONCLUSIONLefty protein may inhibit the formation of scar, its high expression may be related to the embryo scarless wound healing.

Adult ; Cicatrix, Hypertrophic ; metabolism ; Female ; Fibroblasts ; cytology ; metabolism ; Humans ; Left-Right Determination Factors ; metabolism ; Male ; Middle Aged ; Skin ; embryology ; metabolism ; Wound Healing

OBJECTIVETo 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.

METHODSTotal 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.

RESULTSAmong 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.

CONCLUSIONSHigh-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.

Animals ; Cicatrix ; embryology ; genetics ; Epidermis ; embryology ; metabolism ; Fetus ; embryology ; Fibroblast Growth Factor 2 ; analysis ; Follistatin ; analysis ; Gene Amplification ; Gene Expression ; Gene Expression Regulation, Developmental ; Gestational Age ; Oligonucleotide Array Sequence Analysis ; RNA, Messenger ; isolation & purification ; metabolism ; Rats ; Skin ; metabolism ; Transforming Growth Factor beta ; analysis ; Transforming Growth Factor beta1 ; Wound Healing ; genetics

OBJECTIVETo investigate the expression of several homeobox genes during the wound healing in fetal and adult skin and their roles in fetal scarless wound healing.

METHODSThe expressions of PRX-2, HOXB13, HOX2.2 and HOX2.3 during wound healing in fetal and adult skin were determined with in situ hybridization.

RESULTS(1) PRX-2 positive expression could be identified in normal fetal and adult skin, especially in the fetus. But there was difference in location sites of the genes. The positive expression in normal fetal skin was mainly found in the peripheral cells at the hair shafts within dermal papilla layers and was also found in the epithelium. Nevertheless, weak positive expression of PRX-2 was found in the epithelial basal layer cells in normal adult skin but not in dermal tissue. There was strong positive expression of the PRX-2 in the tissue around the wound in fetus but not of that in adults except the epithelial basal layers. (2) Positive expression of HOXB13 could be identified in both normal fetal and adult skins. And the expression was concentrated mainly in hair follicle cells in the dermis and in the basal layer cells in the epithelium. Furthermore, the expression became weak after trauma, especially in fetal skin. (3) The positive expression of HOX2.2 and HOX2.3 in normal fetal skin was observed mainly in the whole layer of the epithelium and especially in the epithelial basal layers. Weak positive expression could be found in the dermis and strong expression found in the tissue near the wound. But there was no positive expression of the HOX genes in normal adult skin and wounds.

CONCLUSIONThe difference in the HOX expression in fetal and adult skin wound healing might be the key factor leading to different wound healing. Homeobox genes might be closely related with the developmental biology.

Adolescent ; Adult ; Animals ; Burns ; pathology ; Child ; Female ; Fetus ; Gene Expression ; Genes, Homeobox ; Homeodomain Proteins ; metabolism ; Humans ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Skin ; embryology ; Wound Healing ; genetics ; Young Adult

OBJECTIVETo explore the change of gene expression of extracellular-signal regulated protein kinase 5 (ERK5) and its upstream signaling molecule (MEK5) in fetal skin of differentially developmental stages and hypertrophic scars.

METHODSAfter morphological characteristics of skin of different developmental stages and hypertrophic scars were detected with pathological methods, gene expression of ERK5 and MEK5 was examined with reverse transcription-polymerase chain reaction analysis (RT-PCR).

RESULTSIn early gestational fetal skin, genes of ERK5 and MEK5 were strongly expressed, while in late gestational skin and children skin, the expression of ERK5 and MEK5 was apparently decreased (P < 0.05). In normal skin, the level of gene expression of ERK5 was lower. In proliferative hypertrophic scars, mRNA content of this gene was apparently increased. In mature scars, the content of this gene transcript was 3.2 times the normal skin. In contrast, the levels of MEK5 transcript in normal skin and hypertrophic scars of various phases showed no substantial changes (P > 0.05).

CONCLUSIONERKS medicating signaling pathway might be involved in regulating cutaneous development at the embryonic stage and determining cutaneous structure ad function. The increase of gene transcription of ERK5 and MEK5 in younger fetal skin might be a reason for rapid proliferation of the skin cells and scraless healing of skin. The activation of ERK5 gene expression in hypertrophic scars versus normal skin might be one of the mechanisms controlling the formation of hypertrophic scars, in which the role of MEK5 needed to be further studied.

Child ; Child, Preschool ; Cicatrix, Hypertrophic ; enzymology ; genetics ; Fetus ; Gene Expression Regulation, Developmental ; Gene Expression Regulation, Enzymologic ; Gestational Age ; Humans ; Mitogen-Activated Protein Kinase 7 ; genetics ; Mitogen-Activated Protein Kinase Kinases ; genetics ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Skin ; embryology ; metabolism ; pathology