Differences in collagen architecture between keloid, hypertrophic scar, normotrophic scar, and normal skin: An objective histopathological analysis

Normotrophic, hypertrophic, and keloidal scars are different types of scar formation, which all need a different approach in treatment. Therefore, it is important to differentiate between these types of scar, not only clinically but also histopathologically. Differences were explored for collagen orientation and bundle thickness in 25 normal skin, 57 normotrophic scar, 56 hypertrophic scar, and 56 keloid biopsies, which were selected on clinical diagnosis. Image analysis was performed by fast fourier transformation. The calculated collagen orientation index ranged from 0 (random orientation) to 1 (parallel orientation). The bundle distance was calculated by the average distance between the centers of the collagen bundles. The results showed that compared with all three types of scars, the collagen orientation index was significantly lower in normal skin, which indicates that scars are organized in a more parallel manner. No differences were found between the different scars. Secondly, compared with normal skin, normotrophic scar, and hypertrophic scar, the bundle distance was significantly larger in keloidal scar, which suggests that thicker collagen bundles are present in keloidal scar. This first extensive histological study showed objective differences between normal skin, normotrophic, hypertrophic, and keloidal sca

An overview of methods for the in vivo evaluation of tissue-engineered skin constructs

Item does not contain fulltextCutaneous wounding often leads to contraction and scarring, which may result in a range of functional, cosmetic, and psychological complications. Tissue-engineered skin substitutes are being developed to enhance restoration of the skin and improve the quality of wound healing. The aim of this review is to provide researchers in the field of tissue engineering an overview of the methods that are currently used to clinically evaluate skin wound healing, and methods that are used to evaluate tissue-engineered constructs in animal models. Clinically, the quality of wound healing is assessed by noninvasive subjective scar assessment scales and objective techniques to measure individual scar features. Alternatively, invasive technologies are used. In animal models, most tissue-engineered skin constructs studied are at least evaluated macroscopically and by using conventional histology (hematoxylin-eosin staining). Planimetry and immunohistochemistry are also often applied. An overview of antibodies used is provided. In addition, some studies used methods to assess gene expression levels and mRNA location, transillumination for blood vessel observation, in situ/in vivo imaging, electron microscopy, mechanical strength assessment, and microbiological sampling. A more systematic evaluation of tissue-engineered skin constructs in animal models is recommended to enhance the comparison of different constructs, thereby accelerating the trajectory to application in human patients. This would be further enhanced by the embracement of more clinically relevant objective evaluation methods. In addition, fundamental knowledge on construct-mediated wound healing may be increased by new developments in, for example, gene expression analysis and noninvasive imaging

Pines

Pinus is the most important genus within the Family Pinaceae and also within the gymnosperms by the number of species (109 species recognized by Farjon 2001) and by its contribution to forest ecosystems. All pine species are evergreen trees or shrubs. They are widely distributed in the northern hemisphere, from tropical areas to northern areas in America and Eurasia. Their natural range reaches the equator only in Southeast Asia. In Africa, natural occurrences are confined to the Mediterranean basin. Pines grow at various elevations from sea level (not usual in tropical areas) to highlands. Two main regions of diversity are recorded, the most important one in Central America (43 species found in Mexico) and a secondary one in China. Some species have a very wide natural range (e.g., P. ponderosa, P. sylvestris). Pines are adapted to a wide range of ecological conditions: from tropical (e.g., P. merkusii, P. kesiya, P. tropicalis), temperate (e.g., P. pungens, P. thunbergii), and subalpine (e.g., P. albicaulis, P. cembra) to boreal (e.g., P. pumila) climates (Richardson and Rundel 1998, Burdon 2002). They can grow in quite pure stands or in mixed forest with other conifers or broadleaved trees. Some species are especially adapted to forest fires, e.g., P. banksiana, in which fire is virtually essential for cone opening and seed dispersal. They can grow in arid conditions, on alluvial plain soils, on sandy soils, on rocky soils, or on marsh soils. Trees of some species can have a very long life as in P. longaeva (more than 3,000 years)