Equine lumican (LUM) cDNA sequence and spatio-temporal expression in an experimental model of normal and pathological wound healing.

The development of exuberant granulation tissue, a situation that in some ways resembles the human keloid, compromises both the aesthetic and functional outcomes of wound repair in horses. To help elucidate the underlying molecular mechanisms the spatio-temporal expression of lumican (LUM) mRNA and protein for their potential contributions to tissue remodelling of body and limb wounds, was examined in an established experimental model. Expression was studied in intact skin and in samples of 1-, 2-, 3-, 4- and 6-week-old wounds of the body and forelimb. Temporal gene expression was determined by reverse transcriptase polymerase chain reaction, and protein expression was mapped immunohistochemically. A significant increase in LUM mRNA expression was observed in response to wounding at both anatomical locations, and a significantly higher mRNA level was recorded in thoracic than in limb wounds at weeks 1, 3 and 6 of repair. The immunohistochemical observations partially corroborated the mRNA data. To the authors' knowledge this study is the first to document that the cDNA for LUM is expressed over the different phases of wound repair in horses and suggests that LUM might be involved in both inflammation and remodelling in response to dermal injury. Further studies are now required to verify and quantify the temporal expression of this protein to provide the basis for targeted therapies that might prevent the development of exuberant granulation tissue in horse wound repair.