Are the cesarean section skin scar characteristics associated with intraabdominal adhesions located at surgical and non-surgical sites

OBJECTIVE

To investigate whether skin scar characteristics are associated with the presence and severity of abdominal or pelvic adhesions in women who have undergone previous cesarean section.

METHODS

In this prospective study, 104 women who had undergone at least one previous cesarean section and were scheduled for laparoscopic surgery due to benign gynaecologic indications were included. Preoperative skin scar characteristics as well as intraoperative adhesions were evaluated using the modified Manchester Scar Scale and the Peritoneal Adhesion Index, respectively.

RESULTS

During laparoscopic surgery, adhesions were detected in the upper region of the abdominal cavity in 30 women, in the middle region in 46 women and in the lower region in 82 women. Total abdominal scar scores were significantly increased in women with adhesions in all three adbominal regions. Multiple cesarean section scars and palpable scars were more common in women with adhesions. Significant positive correlations were found between the skin scar and adhesion scores in all abdominal regions.

CONCLUSION

The skin scar characteristics of the previous caesarean section are associated with the presence and severity of pelvic and abdominal adhesions. Skin scarring especially with palpable texture may be an indicator of adhesion formation in the entire abdominopelvic cavity.

Connexin 43 regulates the expression of wound healing-related genes in human gingival and skin fibroblasts

Fibroblasts are the most abundant connective tissue cells and play an important role in wound healing. It is possible that faster and scarless wound healing in oral mucosal gingiva relative to skin may relate to the distinct phenotype of the fibroblasts residing in these tissues. Connexin 43 (Cx43) is the most ubiquitous Cx in skin (SFBLs) and gingival fibroblasts (GFBLs), and assembles into hemichannels (HCs) and gap junctions (GJs) on the cell membrane. We hypothesized that SFBLs and GFBLs display distinct expression or function of Cx43, and that this may partly underlie the different wound healing outcomes in skin and gingiva. Here we show that Cx43 distinctly formed Cx43 GJs and HCs in human skin and gingiva in vivo. However, in SFBLs, in contrast to GFBLs, only a small proportion of total Cx43 assembled into HC plaques. Using an in vivo-like 3D culture model, we further show that the GJ, HC, and channel-independent functions of Cx43 distinctly regulated wound healing-related gene expression in GFBLs and SFBLs. Therefore, the distinct wound healing outcomes in skin and gingiva may partly relate to the inherently different assembly and function of Cx43 in the resident fibroblasts.

Elevated CD26 Expression by Skin Fibroblasts Distinguishes a Profibrotic Phenotype Involved in Scar Formation Compared to Gingival Fibroblasts

Compared to skin, wound healing in oral mucosa is faster and produces less scarring, but the mechanisms involved are incompletely understood. Studies in mice have linked high expression of CD26 to a profibrotic fibroblast phenotype, but this has not been tested in models more relevant for humans. We hypothesized that CD26 is highly expressed by human skin fibroblasts (SFBLs), and this associates with a profibrotic phenotype distinct from gingival fibroblasts (GFBLs). We compared CD26 expression in human gingiva and skin and in gingival and hypertrophic-like scar-forming skin wound healing in a pig model, and used three-dimensional cultures of human GFBLs and SFBLs. In both humans and pigs, nonwounded skin contained abundantly CD26-positive fibroblasts, whereas in gingiva they were rare. During skin wound healing, CD26-positive cells accumulated over time and persisted in forming hypertrophic-like scars, whereas few CD26-positive cells were present in the regenerated gingival wounds. Cultured human SFBLs displayed significantly higher levels of CD26 than GFBLs. This was associated with an increased expression of profibrotic genes and transforming growth factor-β signaling in SFBLs. The profibrotic phenotype of SFBLs partially depended on expression of CD26, but was independent of its catalytic activity. Thus, a CD26-positive fibroblast population that is abundant in human skin but not in gingiva may drive the profibrotic response leading to excessive scarring.

TGF-beta-induced early gene-1 overexpression promotes oxidative stress protection and actin cytoskeleton rearrangement in human skin fibroblasts

BACKGROUND

Transforming growth factor beta inducible early gene-1 (TIEG-1), a member of the Krüppel-like factor, was identified as a primary response gene for TGF-β. The role of TIEG-1 in skin repair has been mainly addressed in vivo on TIEG-1 null mice model and the mechanism remains unexplored.

METHODS

We investigated the modulation of TIEG-1 expression in normal human skin fibroblasts by either down-expressing or overexpressing the gene. We evaluated reactive oxygen species production and the cell viability of treated cells. The effect of TIEG-1 overexpression was monitored by wound healing assay and immunofluorescence staining of actin fibers organization and alpha-smooth muscle actin (α-SMA). Western blots were carried out to identify the level of expression or phosphorylation of key proteins such as cofilin, Rho GTPases, and p38 mitogen-activated protein kinase (p38 MAPK).

RESULTS

TIEG-1 down-regulation had a deleterious effect on the cell viability. It was significantly reduced (65±5%) and exposure to ultraviolet further increased this effect (47±3%). By contrast, cells overexpressing TIEG-1 had a reduced reactive oxygen species production (75%) compared to control and mock-transfected cells. This overexpression also resulted in formation of actin stress fibers and increased α-SMA expression and an enhanced wound healing feature. RhoB GTPase was upregulated and phosphorylation of cofilin and p38 MAPK was observed.

CONCLUSION

TIEG-1 overexpression in normal human skin fibroblasts results in improved resistance to oxidative stress, myofibroblast-like conversion that involved RhoB signaling pathway with cofilin and p38 MAPK proteins activation.

GENERAL SIGNIFICANCE

This study enlightens the role of TIEG-1 role in skin biology.

Hairless descendants of Mexican hairless dogs: an experimental model for studying hypertrophic scars

BACKGROUND/OBJECTIVE

In previous studies, the author noticed hypertrophic scar formation in hairless dogs. The purpose of this study was to evaluate both grossly and histopathologically hypertrophic scars in hairless dogs to explore any similarities with hypertrophic scars in humans and to introduce these dogs as an appropriate model for further investigation on hypertrophic scarring.

METHODS

Full-thickness wounds were made on the dorsolumbar skin of hairless dogs. Hypertrophic scarring was examined with three methods: clinical observations, dihydroxyphenylalanine (DOPA)-positive melanocytes, and skin histopathology.

RESULTS

Hairless dogs clinically developed the formation of hyperpigmented and hypertrophic scars that did not extend beyond the original wound margins. In hypertrophic scars of hairless dogs, the split epidermal sheet showed an increased number of DOPA-positive melanocytes with well-developed dendrites exhibiting activated melanocytes. There were very few DOPA-positive melanocytes in the repaired skin of haired dogs. Histopathologic examinations demonstrated that hypertrophic scars were fully reepithelialized and granulation tissue formation was accompanied by inflammatory cell infiltration. There was remodeling of thick collagens and fine elastic fibers in the course of hypertrophic scar formation.

CONCLUSION

Experimental hypertrophic scars produced in hairless dogs have morphologic properties similar to those of human hypertrophic scars.

Expression of integrin alphavbeta6 and TGF-beta in scarless vs scar-forming wound healing

Oral mucosal wounds heal with reduced scar formation compared with skin. The epithelial integrin alphavbeta6 is induced during wound healing, and it can activate fibrogenic transforming growth factor beta1 (TGF-beta1) and anti-fibrogenic TGF-beta3 that play key roles in scar formation. In this study, expression of beta6 integrin and members of the TGF-beta pathway were studied in experimental wounds of human gingiva and both gingiva and skin of red Duroc pigs using real-time PCR, gene microarrays, and immunostaining. Similar to human wounds, the expression of beta6 integrin was induced in the pig wounds 7 days after wounding and remained upregulated >49 days. The alphavbeta6 integrin was colocalized with both TGF-beta isoforms in the wound epithelium. Significantly higher expression levels of beta6 integrin and TGF-beta1 were observed in the pig gingival wounds compared with skin. Early gingival wounds also expressed higher levels of TGF-beta3 compared with skin. The spatio-temporal colocalization of alphavbeta6 integrin with TGF-beta1 and TGF-beta3 in the wound epithelium suggests that alphavbeta6 integrin may activate both isoforms during wound healing. Prolonged expression of alphavbeta6 integrin along with TGF-beta3 in the gingival wound epithelium may be important in protection of gingiva from scar formation.

Expression of collagen genes in the cones of skin in the Duroc/Yorkshire porcine model of fibroproliferative scarring

During the past decades there has been minimal improvement in prevention and treatment of hypertrophic scarring. Reasons include the lack of a validated animal model, imprecise techniques to dissect scar into the histologic components, and limited methodology for measurement of gene expression. These problems have been addressed with the Duroc/Yorkshire model of healing, laser capture microdissection, and the Affymetrix Porcine GeneChip. Here we compared collagen gene expression in fibroproliferative healing in the Duroc breed to nonfibroproliferative healing in the Yorkshires. We made shallow and deep dorsal wounds, biopsied at 1, 2, 3, 12, and 20 weeks. We sampled the dermal cones by laser capture microdissection, extracted and amplified the RNA, and hybridized Affymetrix Porcine GeneChips. We also obtained samples of human hypertrophic scar approximately 20 weeks postinjury. Data were normalized and statistical analysis performed with mixed linear regression using the Bioconductor R/maanova package. Genes for further analysis were also restricted with four biologic criteria, including that the 20-week deep Duroc expression match the human samples. Eleven collagen genes and seven collagen types were differentially over expressed in deep Duroc wounds including 1a1, 1a2, 3a1, 4a1, 4a2, 5a1, 5a2, 5a3, 6a3 (transcript variant 5), 14a1 and 15a1. COL7a1 gene was differentially under expressed in deep Duroc wounds. The results suggest that collagens I, III, IV, V, VI, VII, XIV, and XV [corrected] are involved in the process of fibroproliferative scarring. With these clues, we will attempt to construct the regulatory pathway(s) of fibroproliferative healing.

Review of the female Duroc/Yorkshire pig model of human fibroproliferative scarring

Hypertrophic scarring after burns is an unsolved problem and remains as devastating today as it was in the 40s and it may be that the main reason for this is the lack of an accepted, useful animal model. The female, red Duroc pig was described as a model of hypertrophic scarring nearly 30 years ago but then vanished from the literature. This seemed strange since the authors reported that 12 of 12 pigs developed thick scar. In the mid 90s we explored the model and found that, indeed, the red Duroc pig does make thick scar. Other authors have established that the Yorkshire pig does not heal in this fashion so there is the possibility of a same species control. We have continued to explore the Duroc/Yorkshire model and herein describe our experiences. Is it a perfect model of hypertrophic scarring? No. Is it a useful model of hypertrophic scarring? Time will tell. We have now obtained gene expression data from the Duroc/Yorkshire model and analysis is underway.

The Microvasculature in Cutaneous Wound Healing in the Female Red Duroc Pig Is Similar to That in Human Hypertrophic Scars and Different From That in the Female Yorkshire Pig

The female red Duroc pig has been found to be a promising model of hypertrophic scarring. The female Yorkshire pig has been demonstrated to heal in a very different manner, more resembling human normotrophic scarring. Given these observations, we studied microvessel density, an important aspect of wound healing, in human hypertrophic scars and the scars of the female Duroc and Yorkshire pigs. We studied microvessel density in uninjured skin; hypertrophic scars at 6 months or less, 7 to 12, and longer than 12 months; female Duroc tissues at 3 weeks and 3 and 5 months; and similar Yorkshire tissue, including uninjured skin and shallow and deep wounds. Antifactor VIII-related antigen was used to mark the endothelial cells. Computed assessment of microvessel density was used to quantify the microvasculature. In human hypertrophic scars, the microvessels were increased dramatically, and microvessel density and area were significantly elevated. We found similar results in the Duroc tissues at 5 months after deep wounding. In contrast, we found far less microvasculature and, at 5 months, the values had returned to normal in the Yorkshire tissues. This quantitative study of microvessel density further validates the female Duroc pig as an animal model of hypertrophic scarring and the female Yorkshire pig as a control.