Microarray as a New Tool To Study Hypertrophic and Keloid Scarring
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Abstract: Background. Normal wound healing results from a complex set of reactions between blood cells, skin cells, and biochemical mediators including pro- and anti-inflammatory molecules, growth factors, cytokines, hormones, and vitamins. As this cascade of reactions is ultimately regulated by the coordinated expression and silencing of numerous genes, the gene expression analysis of hypertrophic and keloid scarring (HS and KS, respectively) should provide important information and improve our understanding of HS and KS pathophysiology. Microarray is a new tool that can shed light on the complex genetic background that regulates pathologic scarring. This review will describe basic principles of microarray technique for wound care professionals and explain how this technology is contributing to a better understanding of HS and KS biology. Methods. A brief review of the literature on microarray in HS and KS over the last 7 years was conducted. Results. The inter-experiment comparisons are somewhat difficult because of differences in the probes used, diverse source of samples, different time points of wound healing, and in-vivo or ex-vivo analysis. Wound healing gene expression must be studied in an environment where all cells and mediators could show how the regulatory network functions. Conclusion. All results confirmed previous findings about HS and KS related to over-expression of collagen or extracellular matrix (ECM) genes. One conclusion after this initial approach is that a standardized animal model, probe, and software for data analyses to compare results would increase the understanding of HS and KS pathophysiology.
Address correspondence to:
Prof. Alfredo Gragnani, PhD
Rua Napoleão dee Barros, 715-4˚ andar
São Paulo, Brazil 04024 002
Phone: 55 11 5576 4118
E-mail: alfredog@ig.com.br
Hypertrophic scarring (HS) and keloid scarring (KS) are pathologic responses to skin injury induced primarily by burns and deep dermal wounds.1 Both HS and KS share key pathophysiologic findings such as extracellular matrix (ECM) over deposition, deficit of collagen degradation, and decreased fibroblast apoptosis.2
Normal wound healing results from a complex set of reactions between blood cells, skin cells, and myriad biochemical mediators including pro- and anti-inflammatory molecules, growth factors, cytokines, hormones, and vitamins.2 Although abnormalities at different phases of the scarring process have been described in HS and KS, their significance is not completely understood.3 As this cascade of reactions is ultimately regulated by the coordinated expression and silencing of numerous genes, the gene expression analysis of HS and KS should provide important information and improve understanding of HS and KS pathophysiology.
Most HS and KS gene expression studies in the literature are based on polymerase chain reaction (PCR) technology4–7 and in-situ hybridization.8 While both processes accurately assess the gene expression of well known genes involved in wound healing, their application is limited by the small number of genes that can be studied at one time.9
The finalization of the Human Genome Project gave rise to a new and rapidly growing technology that enables researchers to determine the relative expression levels of thousands of genes simultaneously, comparing healthy and affected biological samples—the Deoxyribonucleic acid (DNA) microarray, also known as the gene chip or DNA chip.10
This review will describe basic principles of microarray technique for wound care professionals and explain how this technology is contributing to a better understanding of HS and KS biology.
Microarray Technique
RNA extraction, cDNA synthesis, and labeling.
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