Vascular function and angiogenesis are regulated by vascular endothelial growth factor-A (VEGF). The purpose of this preliminary
study was to address the following questions: Is VEGF expression in the patellar tendon more prevalent in patients with patellar
tendinopathy than in individuals with normal, pain-free patellar tendons? Which cell populations express VEGF in normal and
tendinopathic tendon? Is there a difference in symptom duration between VEGF+ and VEGF− tendons? We collected patellar tendon
tissue from 22 patients undergoing open débridement of the patellar tendon and from 10 patients undergoing intramedullary
nailing of the tibia. VEGF expression was assessed immunohistochemically. Relevant inflammatory and repair cell types were
immunolabeled. VEGF expression was absent from control tendons, but was present in a subset of patients with histopathological
evidence of angiofibroblastic tendinosis. VEGF was expressed in the intimal layer of tendon vessels, but was absent in other
cell types. Patients demonstrating VEGF expression in the patellar tendon had a shorter symptom duration (12 ± 7.8 months)
than patients with no detectable VEGF (32.8 ± 23.5 months). VEGF may contribute to the vascular hyperplasia that is a cardinal
feature of symptomatic tendinosis, particularly in cases with more recent onset.
Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest,
patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
One of more of the authors received funding from the Canadian Institutes of Health Research (AS, DAH, VD), the Worker’s Compensation
Board of British Columbia (AS, VD), the Oslo Sports Trauma Research Center (OL, RB); one of the authors (AS) has received
funding through a CIHR Post-Doctoral Fellowship; one of the authors (DAH) is the Calgary Foundation-Grace Glaum Professor
in Arthritis Research and supported by IGH of CIHR; one of the authors (VD) receives funding through a Michael Smith Foundation
for Health Research Senior Scholar fellowship.
Each author certifies that his or her institution has approved the human protocol for this investigation and that all investigations
were conducted in conformity with ethical principles of research, and that informed consent for participation in the study
was obtained.