The effect of tissue expansion on the expression of collagen type I and type III mRNA in distinct areas of skin in the dog as an animal model

Modulation of cutaneous extracellular collagen contraction by phosphorylation status of p130Cas

Skin can respond to various types of internal and/or external mechanostimuli, such as excessive tension caused by body growth or decompression due to weight loss, which significantly affect skin morphology. Mechanosensors, including p130Cas, are reported to play a role in deformation and subsequent recovery of various tissues including skeletal muscles and blood vessels. However, the role of mechanotransduction via p130Cas in the regulation of skin size remains unclear. In this report, p130Cas activation was manipulated using a fibroblast-embedded collagen gel model or mouse skin contraction model. Inhibition or activation of Src family kinase-mediated phosphorylation of p130Cas significantly depressed and accelerated collagen gel contraction, respectively. The results also demonstrated age-dependent depression of cutaneous p130Cas activation in vivo. Inhibition of p130Cas signaling in our mouse model significantly suppressed recovery from cutaneous deformation. Taken together, our study highlighted the important role of p130Cas in cutaneous mechanotransduction for skin homeostasis.

Cellular and Molecular Responses to Mechanical Expansion of Tissue

The increased use of tissue expander in the past decades and its potential market values in near future give enough reasons to sum up the consequences of tissue expansion. Furthermore, the patients have the right to know underlying mechanisms of adaptation of inserted biomimetic, its bioinspired materials and probable complications. The mechanical strains during tissue expansion are related to several biological phenomena. Tissue remodeling during the expansion is highly regulated and depends on the signal transduction. Any alteration may lead to tumor formation, necrosis and/or apoptosis. In this review, stretch induced cell proliferation, apoptosis, the roles of growth factors, stretch induced ion channels, and roles of second messengers are organized. It is expected that readers from any background can understand and make a decision about tissue expansion.

Bilateral expanded cervico-pectoral "super-thin flap" for entire neck reconstruction

The anterior neck is a difficult area to reconstruct because the neck connects the head and body with multidirectional and complex motility. In this article, we demonstrate our cases of reconstruction with bilateral cervico-pectoral "Super-thin flaps," and discuss our reconstructive methods and results. In this study, we analyze 7 cases (male: 4, female: 3) entire anterior neck reconstruction. Fourteen expanded flaps were employed for their reconstruction. Flap size, flap viability, donor site closure method, esthetic and functional results, and follow up term were analyzed retrospectively. Flap sizes ranged from 8 x 6 cm to 17 x 10 cm. All flap donor sites were closed primarily. All cases achieved full range of motion of the neck after the operation by complete removal of contractured tissues. Natural cervical contour was achieved in 6 patients (86%). Esthetic outcomes were rated to be very good in 4 cases (57%) and good in 2 cases (29%). Expanded cervico-pector super-thin flaps combine the techniques of "flap thinning" and "flap expansion," and the study indicates that flaps are useful for the reconstruction of entire anterior neck.

Intraoperative acute tissue expansion revisited: a valuable tool for challenging skin defects

BACKGROUND

The efficacy of acute tissue expansion (ATE) in achieving skin closure has been strongly debated. Proponents maintain that ATE is efficacious, whereas critics have argued for lack of supporting scientific data and that ATE is no more effective than skin undermining in closure of surface defects.

OBJECTIVE

To compare and actually quantify gain in skin length after extensive undermining of skin edges alone or in combination with ATE in skin defects.

METHODS

Twenty-one consecutive patients undergoing excision and closure of wounds in certain anatomical areas where primary closure is difficult were studied. Actual measurements of the undermined skin before and after ATE were recorded. Immediate problems and long-term follow-up data were analyzed.

RESULTS

ATE, in addition to undermining, provides 1:1.61 +/- 0.23 more skin on each margin than undermining used alone. It is effective, easy to perform, inexpensive, and reproducible, with clearly quantifiable increments of skin stretch. Long-term morbidity is minimal with excellent cosmetic results.

CONCLUSION

ATE provides a useful tool for closure of skin defects that are resistant to simple primary closure even when deeply undermined. It is simple and easily performed in an office setting without much preparation or special equipment.

Smooth muscle-specific expression of SV40 large TAg induces SMC proliferation causing adaptive arterial remodeling

To study the effects of enhanced smooth muscle cell (SMC) proliferation on arterial vessel geometry in the absence of vessel trauma, we developed a transgenic mouse model expressing SV40 large T antigen under control of the 2.3-kb smooth muscle-myosin heavy chain promoter. Transgenic mice studied at ages from 3 to 13 wk showed a 3.2-fold increase in arterial wall SMC density, with 28% of SMC exhibiting proliferative cell nuclear antigen staining, confirming enhanced SMC proliferation, which was accompanied by two- to threefold increases in arterial wall areas (P < 0.05). Remarkably, despite increased vessel wall mass, the lumen area was not compromised, but rather was increased. A tightly conserved linear relationship was found between arterial circumference and wall thickness with slopes of 0.036 for both transgenics (r = 0.93, P < 0.01) and controls (r = 0.77, P < 0.01), suggesting the hypothesis that the conservation of wall stress functions as a primary determinant of adaptive arterial remodeling. This establishes a new model of adaptive vessel remodeling occurring in response to a proliferative input in the absence of mechanical injury or primary flow perturbation.