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Background: The pathogenesis of keloid is poorly understood. Although vigorous investigations have attempted to elucidate the mechanisms or causative factors of keloid, there are little data on why keloids are very intractable and recur easily in each patient., Methods: In an attempt to analyze the possible interaction between human mesenchymal stem cells and keloid-derived fibroblasts, the dual-chamber cell-migration assay, cell proliferation, ultrastructural morphology, and Western blot analysis were used to investigate the production of the extracellular matrices of the coculture., Results: Cell proliferation was not significantly different between keloid-derived fibroblasts and normal dermal fibroblasts during a 4-day observation period. There was a significant cell migration of human mesenchymal stem cells when keloid-derived fibroblasts were placed in the bottom chamber, compared to when normal dermal fibroblasts were placed in the same way in 8-microm diameter pore membranes (190.6 +/- 51.45 and 32.0 +/- 6.20 cells/field, respectively, P < 0.01). With 3-microm diameter pores, the human mesenchymal stem cells migrated in the pores only when the keloid-derived fibroblasts were placed in the bottom chambers (6.4 +/- 3.84 cells/field). Monolayer coculture of human mesenchymal stem cells and keloid-derived fibroblasts demonstrated further functional differentiation, such as collagen secretion and abundant rough endoplasmic reticulum. Western blot analysis of the cells in the modified dual-chamber culture demonstrated most significantly abundant fibronectin expression when the human mesenchymal stem cells contained keloid fibroblasts., Conclusion: The results of this study may indicate that human mesenchymal stem cells participate and recruit in keloid pathogenesis by differentiating themselves toward keloid recalcitrant formation and progression.

Background: Lasers have been used in the treatment of hypertrophic scars and keloids for more than 20 years. Different laser systems have been examined; among them pulsed dye lasers are currently considered the laser of choice in these settings., Objectives: The purpose of this study is to review the pertinent literature and provide updated information on different laser therapies available for treatment of keloids and hypertrophic scars., Methods: A Medline literature search was performed for relevant publications., Results: In this review the results of published studies in the treatment and prevention of hypertrophic scars and keloids are presented. Suggested mechanisms of action are reviewed. A review of the optimal laser parameters to modulate treatment outcome will be discussed. Different lasers are effective in not only the treatment but also the prevention of hypertrophic scars and keloids, among them PDL is more promising. Most of the suggested theories are based on the selective photothermolysis in which the light energy emitted from a vascular laser is absorbed by hemoglobin, generating heat and leading to coagulation necrosis, neocollagenesis, collagen fiber heating with dissociation of disulfide bonds and subsequent collagen fiber realignment., Conclusion: The optimal laser is currently 585 nm PDL, although the recent results of Q-switched 532 nm frequency-doubled Nd:YAG are promising. Early use of lasers are beneficial, especially in those who are prone to develop these lesions.

The biology of wound healing is indeed a complex process. From phase 1 to phase 3, an orderly progression of events take place in the repair process. Various factors influence the rapidity and cosmetic appearance of this phenomenon. Physical, microbial, nutritional and environmental factors all have some role in the end result.