32 Does the Use of Silicone Gel Sheeting Impact the Overall Physiology of Hypertrophic Scar Development? A Feasibility Trial Using Laser Doppler Imaging to Assess Perfusion in Native Skin and Immature Burn Scar

Introduction The use of silicone gel sheeting (SGS) has long been observed clinically as an effective modality in reducing hypertrophic scar (HTS) formation. Although the use of SGS is widely accepted, the exact mechanism is not fully understood. Prevailing theory suggests silicone suppresses collagen production in immature active scar. Collagen production is enhanced as blood flow increases in areas of scar hyperemia. Reduction of blood perfusion to the immature scar may act as a potential mechanism in limiting excessive scar proliferation. Methods Laser Doppler Imaging (LDI) was used to assess 2 areas in 2 subjects (85% TBSA w/ CEA and native skin control): A control site and SGS testing site were traced on the skin of each subject and 5 LDI scans were performed on both subjects: 1) initial without SGS; 2) initial with SGS applied; 3) 4-hours post-SGS application with SGS on; 4) 4-hours post-SGS application immediately after removal; 5) 15-minutes post-SGS removal. The control and testing site for both subjects were then analyzed using the LDI software and the average perfusion units (PU) over the region of interest (ROI1: testing site; ROI2: control site) areas were calculated for each scan. Results Perfusion within both ROI had a marked increase in perfusion for HTS scans after 4-hours when compared to the initial scan. However, after initial SGS application to ROI1, the mean PU decreased by 23.1% while the perfusion to ROI2 remained relatively constant (-5.8%). Subsequently, the ROI2 increased in mean PU by 23.4% 4-hours after the initial scan while the ROI1 showed a blunted response in perfusion in comparison increasing by only 2.3%. Conclusions Perfusion for both NS and HTS were notably decreased when SGS was applied compared to the matched ROI without SGS. In addition, prolonged SGS application created a greater difference in perfusion between silicone (less perfusion) and non-silicone sites (greater perfusion) for both NS and HTS when compared to initial SGS application demonstrating a greater effect on perfusion the longer SGS was worn.

Electrospun Asymmetric Membranes as Promising Wound Dressings: A Review

Despite all the efforts that have been done up to now, the currently available wound dressings are still unable to fully re-establish all the structural and functional properties of the native skin. To overcome this situation, researchers from the tissue engineering area have been developing new wound dressings (hydrogels, films, sponges, membranes) aiming to mimic all the features of native skin. Among them, asymmetric membranes emerged as a promising solution since they reproduce both epidermal and dermal skin layers. Wet or dry/wet phase inversion, scCO2-assisted phase inversion, and electrospinning have been the most used techniques to produce such a type of membranes. Among them, the electrospinning technique, due to its versatility, allows the development of multifunctional dressings, using natural and/or synthetic polymers, which resemble the extracellular matrix of native skin as well as address the specific requirements of each skin layer. Moreover, various therapeutic or antimicrobial agents have been loaded within nanofibers to further improve the wound healing performance of these membranes. This review article provides an overview of the application of asymmetric electrospun membranes as wound dressings displaying antibacterial activity and as delivery systems of biomolecules that act as wound healing enhancers.

A multifunctional substance P-conjugated chitosan hydrochloride hydrogel accelerates full-thickness wound healing by enhancing synchronized vascularization, extracellular matrix deposition, and nerve regeneration

Due to the native skin limitations and the complexity of reconstructive microsurgery, advanced biomaterials are urgently required to promote wound healing for severe skin defects caused by accidents and disasters....

Programming electronic skin with diverse skin-like properties

Simulating the comprehensive functions of native skin—and not simply the perception of external physical stimuli—by electronic skin (e-skin) has gathered increasing attention in the development of wearable devices and human-interactive technology.

ELECTROSPUN GELATIN NANOFIBROUS SCAFFOLDS – APPLICATIONS IN TISSUE ENGINEERING

Electrospinning is highly used technique in the tissue engineering field, particularly in biomedical application [1]. The constricted concepts of this process are based on generate nonwoven nanofibers. The method involves high voltage electricity which is applied to the liquid solution and a collector, which lets the solution force out from a nozzle forming a jet. The jet formed fibers under influence of electrostatic forces concentrated and deposited these on the collector. Main objective of this study was to fabricate gelatin scaffolds with micro/nano-scale for successful wound dressing. Gelatin can mimic the chemical composition, physical structure and structure of the native skin extracellular matrix (ECM). However, the first and main principle in this study is the optimization of parameters of the electrospinning process. The used parameters have a crucial role in obtaining suitable fibers for further cell seeding and cell growth in vitro. With the use of series of various biocompatible polymers and solvents, solutions were tested in various electrospinning settings in order to produce microscale fibers. The scaffolds were analysed with scanning electron microscope images for fiber diameter measurement.

From Grafts to Human Bioengineered Vascularized Skin Substitutes

The skin plays an important role in the maintenance of the human’s body physiological homeostasis. It acts as a coverage that protects against infective microorganism or biomechanical impacts. Skin is also implied in thermal regulation and fluid balance. However, skin can suffer several damages that impede normal wound-healing responses and lead to chronic wounds. Since the use of autografts, allografts, and xenografts present source limitations and intense rejection associated problems, bioengineered artificial skin substitutes (BASS) have emerged as a promising solution to address these problems. Despite this, currently available skin substitutes have many drawbacks, and an ideal skin substitute has not been developed yet. The advances that have been produced on tissue engineering techniques have enabled improving and developing new arising skin substitutes. The aim of this review is to outline these advances, including commercially available skin substitutes, to finally focus on future tissue engineering perspectives leading to the creation of autologous prevascularized skin equivalents with a hypodermal-like layer to achieve an exemplary skin substitute that fulfills all the biological characteristics of native skin and contributes to wound healing.

Asymmetric Membranes: A Potential Scaffold for Wound Healing Applications

Currently, due to uprising concerns about wound infections, healing agents have been regarded as one of the major solutions in the treatment of different skin lesions. The usage of temporary barriers can be an effective way to protect wounds or ulcers from dangerous agents and, using these carriers can not only improve the healing process but also they can minimize the scarring and the pain suffered by the human. To cope with this demand, researchers struggled to develop wound dressing agents that could mimic the structural and properties of native skin with the capability to inhibit bacterial growth. Hence, asymmetric membranes that can impair bacterial penetration and avoid exudate accumulation as well as wound dehydration have been introduced. In general, synthetic implants and tissue grafts are expensive, hard to handle (due to their fragile nature and poor mechanical properties) and their production process is very time consuming, while the asymmetric membranes are affordable and their production process is easier than previous epidermal substitutes. Motivated by this, here we will cover different topics, first, the comprehensive research developments of asymmetric membranes are reviewed and second, general properties and different preparation methods of asymmetric membranes are summarized. In the two last parts, the role of chitosan based-asymmetric membranes and electrospun asymmetric membranes in hastening the healing process are mentioned respectively. The aforementioned membranes are inexpensive and possess high antibacterial and satisfactory mechanical properties. It is concluded that, despite the promising current investigations, much effort is still required to be done in asymmetric membranes.

Bioengineered Skin Intended for Skin Disease Modeling

Clinical use of bioengineered skin in reconstructive surgery has been established for more than 30 years. The limitations and ethical considerations regarding the use of animal models have expanded the application of bioengineered skin in the areas of disease modeling and drug screening. These skin models should represent the anatomical and physiological traits of native skin for the efficient replication of normal and pathological skin conditions. In addition, reliability of such models is essential for the conduction of faithful, rapid, and large-scale studies. Therefore, research efforts are focused on automated fabrication methods to replace the traditional manual approaches. This report presents an overview of the skin models applicable to skin disease modeling along with their fabrication methods, and discusses the potential of the currently available options to conform and satisfy the demands for disease modeling and drug screening.