Humans ; Reconstructive Surgical Procedures ; adverse effects ; Surgery, Plastic

The scar formation and chronic ulcer development are the iain sequelae faced by surgeons in the treatmemt of wounds. Therefore,the prevention and treatment of these sequelae are the main tasks for clinicians.In this paper,the current research concerning both sequelae is reviewed.The authors emphasize that the use of some high technologiesl, such as stem cell technology, clone technology and tissue engineering may bring the hope in improving the treatment and prevention of these sequelae.

The cytokine-receptor- heparin sulfate functional complex combined by cytokines, cytokine receptors, and heparin sulfate chains formed by concatenation of heparin sulfate proteoglycans (HSPG), an important component of extracellular matrix and modified by some relative enzymes, can regulate the density of cytokine receptors and their intracellular signal transduction. This article focused on the regulatory function of this complex. Many morphological abnormalities and diseases occur when the complex is dysfunctional.

To explore the change in gene expressions of p38 mitogen-activated protein kinase (p38MAPK) and its upstream signal-regulated molecule (mkk3 and mkk6) in normal skin versus hypertrophic scars underlying its potentially biological significance. Total RNAs were isolated from 8 specimens of hypertrophic scars and 8 specimens of normal skin, then they were purified to mRNAs, and the gene expression of mkk3, mkk6 and p38MAPK was examined with reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the intensities of gene expression of mkk6 and p38MAPK were weak in normal skins, while the expression of these 2 genes was significantly elevated in hypertrophic scars compared with normal skins (P0.05). In hypertrophic scar, the elevation of mkk6 and p38MAPK gene expression, which plays pilot roles in cell proliferation, may be one of the mechanisms controlling the formation of hypertrophic scars.

To explore the activities of signal transduction pathway involved in heat-stressed fibroblast in vitro. Human dermal fibroblasts were cultured in Dulbecco′s modified Eagle′s medium with 5% calf serum at 5%CO 2 in a water-saturated atmosphere. Cultured cells were heated to 45℃ for 10min. Western blotting was used to detect ERK1/2 and JNK expression, and the expression of caspase-3 protein was observed by immunoflurescence technique. The results showed that the MAPKs signal transduction pathway was activated in heat-stressed fibroblasts. The expression of JNK reached the peak at 60min, then maintained up to 180min. The expression of ERKs peaked at 30min, then lowered. The expression of caspase-3 was weak at 30min after heat-stress, and became evidently strong at 60min. The signal pathway of ERKs and JNK played important roles in the changes in biologic characteristics of fibroblasts after heat-stress.

To investigate the distribution of epidermal stem cells in regenerating wound tissues, and to elucidate the role of epidermal stem cells during wound repair. 80 circular full-thickness wounds were produced on both sides of the back in 20 male Wistar rats labeled 60 days previously with 5-Bromodeoxyuridine (BrdU) (4 wounds in each animal). Then these 80 wounds were randomly divided into 2 groups as follows: group A: with topical treatment of epidermal growth factor (n=40) and group B: no-treatment (n=40). BrdU, ? 1 integrin and keratin19 (K19) were employed to determine the epidermal stem cells with streptavidin-peroxidase (SP)immunohistochemical method, and the speed and quality of epithelialization were determined with routine histological methods with HE staining on the 3rd, 7th, 14th, and 21st day after the wounding. Results showed that the healing rate of wounds was 80% in group A (32/40) and 60% in group B (24/40). No cells with positive immunostaining for BrdU, ? 1 integrin, or K19 were found in the granulation tissue of all wounds in both groups during the healing process. However, a few BrdU, ? 1 integrin and K19 positive cells, bearing no anatomic relation with the epidermal stem cells in the basal layer, were found scattering in the stratum spinosum and stratum granulosum of the epidermis on the wound edges. The results suggested that epidermal stem cells appearing on the wound edges were the main source of re-epithelialization of granulating wounds.

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.

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.\ \ \ \}

The differentiation of cell is a very important biological process. In this paper, the current understanding and advances in research on dedifferentiation are reviewed. Giving more efforts to study this subject may help us disclose the mechanisms and treatment for some diseases.

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.