Nucleotide structure and expression of equine pigment epithelium-derived factor during repair of experimentally induced wounds in horses

Objective-To clone full-length equine pigment epithelium-derived factor (PEDF) complementary DNA (cDNA) and to evaluate its temporal expression during repair of wounds in horses. Animals-4 clinically normal 2- to 3-year-old Standardbred mares Procedures-Full-length equine PEDF cDNA was cloned by screening size-selected cDNA libraries derived from biopsy specimens obtained from the wound edge 7 days after experimental creation of a 6.25-cm(2) full-thickness wound in the skin of the lateral thoracic wall. Expression was evaluated in normal skin and in biopsy specimens obtained weekly from experimentally induced wounds on the trunk and limbs of horses. Temporal gene expression was determined by use of reverse transcriptase PCR assay. Results-Equine PEDF shared 87% sequence and 88% peptide homology with human PEDF Wounding caused upregulation of PEDF mRNA, which did not return to baseline by the end of the study in either anatomic location. Relative overexpression was evident in wounds on the trunk, compared with expression for wounds on the limbs. Conclusions and Clinical Relevance-This study characterized full-length equine cDNA for PEDF and determined that the gene for PEDF appeared to be upregulated in response to dermal wounding. Although the cause of exuberant granulation tissue is probably multifactorial, these data suggested that PEDF, via its potent antiangiogenic capabilities, may contribute to superior healing in wounds on the trunks of horses by protecting such wounds from excessive formation of vascular granulation tissue that characterizes wounds on the limbs of this species. (Am J Vet Res 2009;70:112-117)