Keloid is a fibrotic disease characterized by abnormal accumulation of extracellular matrix in the dermis. The keloid matrix contains excess collagen and glycosaminoglycans (GAGs), but lacks elastic fiber. However, the roles of these matrix components in the pathogenesis of keloid are largely unknown. Here, we show that elastin and DANCE (also known as fibulin-5), a protein required for elastic fiber formation, are not deposited in the extracellular matrix of keloids, due to excess accumulation of chondoitin sulfate (CS), although the expression of elastin and DANCE is not affected. Amount of CS accumulated in the keloid legion was 6.9-fold higher than in normal skin. Fibrillin-1, a scaffold protein for elastic fiber assembly, was abnormally distributed in the keloid matrix. Addition of purified CS to keloid fibroblast culture resulted in abnormal deposition of fibrillin-1, concomitant with significantly decreased accumulation of elastin and DANCE in the extracellular matrix. We propose that CS plays a crucial role in the development of keloid lesions through inhibition of elastic fiber assembly. (C) 2009 Elsevier Inc. All rights reserved.