Scar, either hypertrophic scar or keloid, is one of the most common complications due to proliferative disorder of fibrosis in the process of wound healing after burn injuries, trauma, and surgical operations. To repair the cosmetic and functional impairments caused by scars poses a great challenge to all the burn surgery workers. With the advances in both basic research and clinical treatment, the understanding of scar formation and the therapeutic strategies of scar have been improved significantly. However, the remaining problems are still outstanding. In this discussion, the advances and problems in the scientific research in this field, including genetic predisposition, candidate gene, dysfunction of fibroblasts, interaction between fibroblasts and keratinocytes, as well as animal models for hypertrophic scar and keloid were summarized. In addition, the progresses in the clinical therapies are also discussed, including pressure treatment, silicone gel sheeting, corticosteroids, laser, and other emerging treatment strategies. The understanding and treatment of scar will improve in the future with further deepening basic research and clinical trials with stricter standard of assessment.
Burns ; pathology ; Cicatrix ; genetics ; pathology ; therapy ; Fibroblasts ; cytology ; Humans ; Keratinocytes ; cytology

The immortalization and transformation of cultured human cells has far-reaching implications for both cell and cancer biology. Human cell transformation studies will increase our understanding of the mechanisms underlying carcinogenesis and differentiation. The neoplastic process can now be studied in a model human cell culture system. The accompanying biochemical and genetic changes, once identified, will help define the relationship between malignancy and differentiation. The present studies indeed demonstrate that the neoplastic process can now be studied in a human cell model system. Primary human cells treated with various carcinogens became immortalized in culture but were not tumorigenic. Additional exposure to either retroviruses, chemical carcinogenes or X-ray irradiation to these cells induced morphological alterations associated with the acquisition of neoplastic properties. These findings demonstrate the malignant transformation of human primary cells in culture by the combined action of either a DNA transforming virus and a retrovirus or a DNA virus and a chemical or X-ray irradiation, and support an multistep process for neoplastic conversion. It has been known that normal human cells in culture are remarkably resistant to experimentally induced tumorigenicity. However, as shown above, normal human cells could now be transformed into tumorigenic cells.
*Cell Transformation, Neoplastic/genetics ; Cells, Cultured ; DNA, Viral ; Fibroblasts/pathology ; Human ; Keratinocytes/cytology/pathology ; Osteosarcoma/genetics/pathology

Skin wound healing is a complex event, and interrupted wound healing process could lead to scar formation. The aim of this study was to examine the morphological changes of scar tissue. Pathological staining (HE staining, Masson's trichrome staining, methenamine silver staining) was used to evaluate the morphological changes of regenerating epidermis in normal skin and scar tissue, and immunofluorescence staining to detect the expression of collagen IV, a component of basement membrane (BM), and the expression of integrinβ4, a receptor for BM laminins. Additionally, the expression of CK14, CK5, and CK10 was measured to evaluate the proliferation and differentiation of keratinocytes in normal skin and scar tissue. The results showed that the structure of the skin was histologically changed in scar tissue. Collagen IV, expressed under the epidermis of normal skin, was reduced distinctly in scar tissue. Integrinβ4, expressed in the basal layer of normal skin, was found absent in the basal layer of scar tissue. Additionally, it was found that keratinocytes in scarring epidermis were more proliferative than in normal skin. These results indicate that during the skin wound healing, altered formation of BM may affect the proliferation of keratinocytes, reepithelial and tissue remodeling, and then result in scar formation. Thus, remodeling BM structure during wound repair may be beneficial for improving healing in cutaneous wounds during clinical practice.
Adolescent ; Adult ; Cicatrix ; metabolism ; pathology ; Collagen Type IV ; metabolism ; Female ; Humans ; Integrin beta4 ; metabolism ; Keratinocytes ; cytology ; metabolism ; pathology ; Male ; Skin ; cytology ; metabolism ; pathology

OBJECTIVETo investigate the origin of myofibroblasts in oral submucous fibrosis.

METHODSThe oral keratinocytes and fibroblasts were isolated and cultured. The expression of the alpha-smooth muscle actin in the fibroblasts was examined by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTSNo difference was found in expression of alpha-smooth muscle actin between the fibroblasts that were directly stimulated by arecoline and the control. The expression of alpha-smooth muscle actin in the keratinocyte and fibroblast-cocultured group was higher than in the control group, and higher in fibroblasts cocultured with keratinocytes preprocessed by arecoline than in fibroblasts cocultured with keratinocytes without preprocessed by arecoline.

CONCLUSIONSThe differentiation of myofibroblasts from fibroblasts in oral submucous fibrosis might be induced by the interaction of arecoline and keratinocyte.

Actins ; metabolism ; Arecoline ; pharmacology ; Cell Differentiation ; drug effects ; Cells, Cultured ; Coculture Techniques ; Fibroblasts ; cytology ; metabolism ; Humans ; Keratinocytes ; cytology ; Mouth Mucosa ; cytology ; Oral Submucous Fibrosis ; metabolism ; pathology

Our objective is to determine the quality of tissue engineered human skin via immunostaining, RT-PCR and electron microscopy (SEM and TEM). Culture-expanded human keratinocytes and fibroblasts were used to construct bilayer tissue-engineered skin. The in vitro skin construct was cultured for 5 days and implanted on the dorsum of athymic mice for 30 days. Immunostaining of the in vivo skin construct appeared positive for monoclonal mouse anti-human cytokeratin, anti-human involucrin and anti-human collagen type I. RT-PCR analysis revealed loss of the expression for keratin type 1, 10 and 5 and re-expression of keratin type 14, the marker for basal keratinocytes cells in normal skin. SEM showed fibroblasts proliferating in the 5 days in vitro skin. TEM of the in vivo skin construct showed an active fibrocyte cell secreting dense collagen fibrils. We have successfully constructed bilayer tissue engineered human skin that has similar features to normal human skin.
Fibroblasts/*cytology ; Keratinocytes/*cytology ; Mice, Nude ; Microscopy, Electron ; Microscopy, Electron, Scanning ; Quality Control ; Regeneration/physiology ; Skin/pathology ; Skin Transplantation/pathology ; Skin Transplantation/*standards ; Tissue Engineering/*standards

In covering wounds, efforts should include utilization of the safest and least invasive methods with goals of achieving optimal functional and cosmetic outcome. The recent development of advanced wound healing technology has triggered the use of cells to improve wound healing conditions. The purpose of this review is to provide information on clinically available cell-based treatment options for healing of acute and chronic wounds. Compared with a variety of conventional methods, such as skin grafts and local flaps, the cell therapy technique is simple, less time-consuming, and reduces the surgical burden for patients in the repair of acute wounds. Cell therapy has also been developed for chronic wound healing. By transplanting cells with an excellent wound healing capacity profile to chronic wounds, in which wound healing cannot be achieved successfully, attempts are made to convert the wound bed into the environment where maximum wound healing can be achieved. Fibroblasts, keratinocytes, adipose-derived stromal vascular fraction cells, bone marrow stem cells, and platelets have been used for wound healing in clinical practice. Some formulations are commercially available. To establish the cell therapy as a standard treatment, however, further research is needed.
Blood Platelets/metabolism ; Cell- and Tissue-Based Therapy ; Diabetes Mellitus, Type 2/complications/pathology ; Fibroblasts/cytology/transplantation ; Humans ; Keratinocytes/cytology/transplantation ; Stromal Cells/cytology/transplantation ; Tissue Engineering ; Ulcer/etiology/therapy ; *Wound Healing

Stromal cells provide a crucial microenvironment for overlying epithelium. Here we investigated the expression and function of a stromal cell-specific protein, stromal cell-derived factor-1 (SDF-1), in normal human skin and in the tissues of diseased skin. Immunohistology and laser capture microdissection (LCM)-coupled quantitative real-time RT-PCR revealed that SDF-1 is constitutively and predominantly expressed in dermal stromal cells in normal human skin in vivo. To our surprise, an extremely high level of SDF-1 transcription was observed in the dermis of normal human skin in vivo, evidenced by much higher mRNA expression level than type I collagen, the most abundant and highly expressed protein in human skin. SDF-1 was also upregulated in the tissues of many human skin disorders including psoriasis, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). Double immunostaining for SDF-1 and HSP47 (heat shock protein 47), a marker of fibroblasts, revealed that fibroblasts were the major source of stroma-cell-derived SDF-1 in both normal and diseased skin. Functionally, SDF-1 activates the ERK (extracellular-signal-regulated kinases) pathway and functions as a mitogen to stimulate epidermal keratinocyte proliferation. Both overexpression of SDF-1 in dermal fibroblasts and treatment with rhSDF-1 to the skin equivalent cultures significantly increased the number of keratinocyte layers and epidermal thickness. Conversely, the stimulative function of SDF-1 on keratinocyte proliferation was nearly completely eliminated by interfering with CXCR4, a specific receptor of SDF-1, or by knock-down of SDF-1 in fibroblasts. Our data reveal that extremely high levels of SDF-1 provide a crucial microenvironment for epidermal keratinocyte proliferation in both physiologic and pathologic skin conditions.
Adult ; Cell Proliferation ; Chemokine CXCL12 ; genetics ; Epidermal Cells ; Epidermis ; pathology ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; Fibroblasts ; metabolism ; Gene Expression Regulation ; Humans ; Keratinocytes ; cytology ; pathology ; Signal Transduction ; Skin Diseases ; genetics ; pathology

OBJECTIVETo clarify expression and subcellular localization of XIAP and XAF1 protein in human normal oral keratinocytes (hNOK) and Tca8113 cells human tongue carcinoma cell line.

METHODSThe hNOKs and Tca8113 cells were cultured in vitro. Expression and subcellular localization of XIAP and XAF1 protein were examined by combination of indirect immunofluorescence and confocal laser scanning microscopy.

RESULTSXIAP expression was weak in the hNOKs and fluorescence staining localized chiefly in the cytoplasm and perinuclear areas. In the Tca8113 cells, high level of XIAP protein could be detected in both the cytoplasm and the nucleus. In the hNOKs, XAF1 distributed mostly in the nucleus. Homogeneous nuclear and cytoplasmic distribution of XAF1 could be visualized in the Tca8113 cells.

CONCLUSIONSIn cancerization of oral mucosa, XIAP protein could play an important antiapoptotic role by overexpression, while XAF1 protein does not appear to antagonize effectively the role of XIAP.

Apoptosis ; Cell Line, Tumor ; Cells, Cultured ; Humans ; Intracellular Signaling Peptides and Proteins ; Keratinocytes ; metabolism ; pathology ; Mouth Mucosa ; cytology ; metabolism ; Neoplasm Proteins ; metabolism ; Tongue Neoplasms ; metabolism ; pathology ; X-Linked Inhibitor of Apoptosis Protein ; metabolism

OBJECTIVETo investigate the effect of a novel retinoid CD437 and all-trans retinoic acid (ATRA) in inducing cell apoptosis and inhibiting the proliferation of human epidermoid carcinoma A431 cells and normal human epidermal keratinocytes.

METHODSMTT assay was used to determine the inhibitory effects of CD437 and ATRA on the growth of A431 cells and normal human epidermal keratinocytes, and the cell morphological changes were observed microscopically. Flow cytometry was used to investigate the effect of CD437 and ATRA on the cell cycle and apoptosis.

RESULTSCD437 was more effective than ATRA in inhibiting the proliferation of A431 cells and normal human epidermal keratinocytes. CD437 increased the percentage of sub-G1 populations in A431 cells and induced G1 arrest in normal human epidermal keratinocytes. ATRA appeared to be relatively ineffective for inducing apoptosis in A431 cells as compared to CD437. CD437 did not duce obvious apoptosis in normal human epidermal keratinocytes.

CONCLUSIONCD437 is more effective than ATRA in inhibiting the proliferation and inducing apoptosis in A431 cells and shows selective apoptosis-inducing effect against malignant keratinocytes, suggesting its potential in the prevention or treatment of cutaneous carcinoma.

Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Carcinoma, Squamous Cell ; pathology ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Cells, Cultured ; Epidermis ; drug effects ; pathology ; Flow Cytometry ; Humans ; Keratinocytes ; cytology ; drug effects ; Male ; Retinoids ; pharmacology ; Tretinoin ; pharmacology ; Young Adult

Despite the various responses of human skin to female sex hormones, cellular and subcellular targets and the mechanisms of action of estrogen and progesterone in human skin are not well understood. The detection of estrogen receptor (ER) and progesterone receptor (PR) in the skin is of great importance to understand the effect of estrogen and progesterone. In primary cultures of human keratinocytes, expression of ER and PR was monitored by immunocytochemistry and reverse transcriptase polymerase chain reaction (RT-PCR). Paraffin embedded skin tissues were stained with monoclonal antibodies to human ER and PR by immunohistochemistry. Cultured human keratinocytes expressed cytoplasmic PR protein and PR mRNA transcripts. By contrast, ER was detected only at the mRNA level. Suprabasal keratinocytes from samples of pruritic urticarial papules, plaques of pregnancy (PUPPP) and psoriasis were stained positively only for PR, while those from samples of erythema nodosum were negative for both ER and PR. Lesional epidermis of PUPPP showed positive PR immunoreactivity, while nonlesional epidermis did not. No other cells in the normal human skin were stained with ER and PR. The present study suggests that by expressing PR human keratinocytes act as targets for progesterone action.
Adolescence ; Adult ; Aged ; Cells, Cultured ; Female ; Gene Expression ; Human ; Immunoenzyme Techniques ; Infant ; Keratinocytes/metabolism* ; Keratinocytes/cytology ; Male ; Middle Age ; Receptors, Estrogen/genetics ; Receptors, Estrogen/biosynthesis ; Receptors, Progesterone/genetics* ; Receptors, Progesterone/biosynthesis ; Reverse Transcriptase Polymerase Chain Reaction ; Sequence Analysis, DNA/methods ; Skin/pathology ; Skin/metabolism ; Skin Diseases/metabolism