Aberrant Notch signalling contributes to hypertrophic scar formation by modulating the phenotype of keratinocytes.

Hypertrophic scar (HS) is characterized by fibroblast hyperproliferation and excessive matrix deposition. Aberrant keratinocyte differentiation and their abnormal cytokine secretion are said to contribute to HS by activating fibroblasts. However, the signalling pathway causing the aberrant keratinocytes in HS has remained unidentified thus far. Given that Notch signalling is crucial in initiating keratinocyte differentiation, we hypothesized that Notch signalling contributes to HS by modulating the phenotype of keratinocytes. We found that Notch1, Notch intracellular domain, Jagged1 and Hes-1 were overexpressed in the epidermis of patients with HS. Supernatants from recombinant-Jagged1-treated keratinocyte cultures could accelerate dermal fibroblast proliferation and collagen production. Furthermore, Jagged1 induced keratinocyte differentiation and upregulated the expression of fibrotic factors, including transforming growth factors ß1 and ß2 , insulin-like growth factor-1, connective tissue growth factor, vascular endothelial growth factor and epidermal growth factor, while DAPT (a Notch inhibitor) significantly suppressed these processes. In a rabbit ear model of HS, local application of DAPT downregulated the production of fibrotic factors in keratinocytes, together with ameliorated scar hyperplasia. Our findings suggest that Notch signalling contributes to HS by modulating keratinocyte phenotype. These results provide new insights into the pathogenesis of HS and indicate a potential therapeutic target.

Histone deacetylase inhibitor reduces hypertrophic scarring in a rabbit ear model.

BACKGROUND: Hypertrophic scars result from excessive collagen deposition at sites of healing dermal wounds and could be functionally and cosmetically problematic. The authors tested the ability of the histone deacetylase inhibitor trichostatin A to reduce hypertrophic scar formation in a rabbit ear model. METHODS: The authors have developed a reliable rabbit model that results in hypertrophic scarring. Four 1-cm, full-thickness, circular wounds were made on each ear. After the wounds reepithelialized, 0.02% trichostatin A was injected intradermally into the wounds in the treatment group. Expression of collagen I and fibronectin was detected by reverse transcription polymerase chain reaction and Western blot analysis at postoperative day 23. Scar hypertrophy was quantified by measurement of the scar elevation index at postoperative day 45. RESULTS: Compared with the control group, injection of trichostatin A led to much more normal-appearing scars in the rabbit ear. The scar elevation index at postoperative day 45 was significantly decreased after injection of trichostatin A compared with untreated scars. Furthermore, the authors confirmed the decreased expression of collagen I and fibronectin at postoperative day 23 (after the rabbits had been treated with trichostatin A for 1 week) in the treated scars compared with the control scars according to reverse transcription polymerase chain reaction and Western blot analysis. CONCLUSIONS: The introduction of trichostatin A can result in the decreased formation of hypertrophic scars in a rabbit ear model, which is corroborated by evidence of decreased collagen I and fibronectin synthesis.

Clinical application of full-face, whole, full-thickness skin grafting: a case report.

A considerable portion of burn patients suffers severe full-face burns. Even after they were treated, some severe abnormalities still stay with them such as upper- and lower-eyelid ectropions, upper- and lower-lip ectropions, microstomia and extensive facial scar hyperplasia accompanied with pruritus. Patients suffer a great deal physically, emotionally and socially. Here we conclude our treatment experience of full-face burns with the full-face, whole, full-thickness skin grafting, which has not yet reported in the literature. We transplanted a whole, full-thickness skin graft to cover the wound in the primary operation and then remedied eyelid ectropions and microstomia in the operation that followed. The results of a 4-year-follow-up suggest that the patient has recovered part of facial expression and sensation without any geographic scars. Full-face, whole, full-thickness skin grafting appears to be an effective and relatively simple method for full-face burns that do not respond well to facial composite tissue allotransplantation (CTA).

Trichostatin A inhibits collagen synthesis and induces apoptosis in keloid fibroblasts.

Keloid, a fibro-proliferative benign tumor of skin, is characterized by an enriched milieu of growth factors and an abundant accumulation of extracellular matrix (ECM). Transforming growth factor (TGF)-ß1 is well known as the crucial fibrogenic cytokine promoting ECM production and tissue fibrosis in keloid forming. Epigenetic modifications have been shown to play a role in the pathogenesis of cancer as well as autoimmune and inflammatory disorders. Recent publication reports epigenetic modifications in keloid fibroblasts that include an altered pattern of DNA methylation and histone acetylation. Therefore, the field of epigenetics may provide a new therapeutic idea for keloid treatment strategies. Currently, there is some evidence from experimental studies that histone deacetylase (HDAC) inhibitor Trichostatin A (TSA) causes abrogation of TGF-ß1 induced collagen synthesis in skin fibroblasts. Furthermore, TSA could suppress proliferation and induce apoptosis in a broad spectrum of tumor cells both in vitro and in vivo. These findings suggest that TSA could also cause abrogation of TGF-ß1 induced collagen synthesis and induce apoptosis of proliferating keloid fibroblasts.

Rolling autogenetic dermis up to form a tube may be used as scaffold in tissue-engineered blood vessels.

Coronary and peripheral artery bypass grafting are widely being used to deal with vascular deficiencies currently, and a man-made synthetic tube or autogenous arteries or veins are needed a lot. But one's autogenous arteries or veins are limited, and artificial graft substitute isn't yet available in clinical applications because of many disadvantages. Various polymeric materials have been used as scaffolds, but without satisfying results due to intimal hyperplasia and the rate of degradation. Autogenetic dermis, which has the advantages of resistance to immunogenicity, good biocompatibility, and appropriate mechanical and physiological properties, has gained our attention to use it as a scaffold for tissue-engineered blood vessels. What is more, autogenetic dermis can be harvested easily. So we postulate that autogenetic dermis rolled up to form a tube may be an ideal scaffold for tissue-engineered blood vessels.

[Blocking of Notch signaling decreased scar formation in rabbit ear hypertrophic scar model].

OBJECTIVE: To investigate the effects of Notch signaling on scars in a rabbit ear model of hypertrophic scarring. METHODS: The hypertrophic scar of rabbits' ears was reproduced. The left rabbit's ear wounds as the N-[N-(3,5-difluorophenacetyl-L-alanyl)]-(S)-phenylglycine t-butyl ester (DAPT) treated group were treated intradermally with the gamma-secretase inhibitor DAPT to inhibit the activation of Notch at 1, 3, 7 and 14 day time points. The right ears as the control group were treated with normal saline at the same time points. Experimental and control wounds were harvested on days 14, 21, 28 and 35 post wounding, and then examined histologically to quantify hypertrophic index and fibroblasts. The expression of epidermal differentiation markers-keratin 14 (K14), keratin 19 (K19), Involucrin and Notch downstream molecules-P21, P63 were examined and analyzed with immunohistochemistry staining. RESULTS: Both hypertrophic index (1.93 +/- 0.32, 1.82 +/- 0.36, 1.79 +/- 0.25) and number of fibroblasts [(4.08 +/- 0.88), (3.30 +/- 0.53), (3.19 +/- 0.73) x 10(3)/mm(2)] in the DAPT treated group were significantly reduced on days 21, 28 and 35, compared with the control group [2.56 +/- 0.29, 2.61 +/- 0.30, 2.58 +/- 0.39, and (5.45 +/- 0.99), (4.80 +/- 1.13), (4.43 +/- 1.17) x 10(3)/mm(2), all P < 0.01)]. The K19, K14 and P63 increased their expression in the DAPT treated group (28.6% +/- 5.7%, 53.1% +/- 4.5%, 57.0% +/- 5.8%) relative to the control group (10.1% +/- 2.8%, 30.8% +/- 4.9%, 16.5% +/- 2.2%, all P < 0.01) on day 14 post wounding, while the Involucrin and P21 decreased their expression in the DAPT treated group (12.3% +/- 1.9%, 11.0% +/- 1.7%) relative to the control group (29.3% +/- 4.6%, 44.3% +/- 3.5%, both P < 0.01). CONCLUSION: Inactivation of Notch signaling will inhibit scar epidermis to over-differentiation, and thereby inhibit proliferation of hypertrophic scars in the rabbit ears.

Wedge-shaped excision and modified vertical mattress suture fully buried in a multilayered and tensioned wound closure.

BACKGROUND: A successful deep multilayered wound suture should provide a firm tension-relieving closure, good wound-edge eversion, hemostasis, and minimal intradermal extraneous materials. However, this is not always achieved with a single standard technique. The authors describe their modification of a wound closure method that can rapidly and reliably achieve these results. METHODS: A wedge-shaped excision was adopted to obtain a trapezoid pattern transect, after which a modified fully buried vertical mattress suture technique was used to close the wound. These techniques were compared with the standard excision and suture techniques used for the same patient at different times after surgery. RESULTS: The wedge-shaped excision can facilitate good wound-edge eversion, and the modified fully buried vertical mattress suture can provide firm tension relief and optimal apposition. Compared with conventional excision and suture techniques, the described techniques brought about a better outcome in terms of hypertrophic scar prevention. CONCLUSION: The described modified technique seems to be more efficient than conventional procedures used to prevent hypertrophic scar formation.

Aberrant Notch signaling: a potential pathomechanism of vitiligo.

Vitiligo is characterized by a localized and progressive loss of melanocytes which are pigment cells responsible for the pigmentation of human. The etiopathogenetic mechanisms leading to melanocytes loss in vitiligo lesions are not yet fully understood and no effective treatment or cure exists. Notch signaling has been shown to control many cellular functions of melanocytes. Activation of Notch signaling occurs during the formation of melanocytic tumors and inactivation of Notch signaling causes a dramatic elimination of melanocytes precursors. So we postulate that inactivation of Notch signaling in the melanocytes may be a potential pathomechanism of vitiligo. If the hypothesis was proved to be practical, we could provide new understanding of the etiology of vitiligo and produce new therapeutic avenues.