Tendinopathic supraspinatus tenocytes may have a neuroendocrine-like function, secreting CGRP, SP and VEGF: a pilot immunohistochemistry study

We wanted to observe and compare the appearance of neurovascular tissue from tendon ex vivo, in patients with and without painful rotator cuff tendinopathy. Supraspinatus tendons were biopsied from 5 participants with painful tendinopathy and normal tendon from a young male. Slides were stained with haematoxylin and eosin and toluidine blue for histological assessment. Immunohistochemical markers for general nerves (protein gene-product 9.5 and synaptophysin), sensory nerves (calcitonin gene-related peptide; substance-P) and vascularisation (vascular endothelial growth factor) were used. PGP9.5 and CGRP-immunoreactive fibres were associated with vessels in cases and control. Synaptophysinlabelled fibres were observed in close relation to vessels in tendinopathy. PGP9.5, CGRP, SP and VEGF-immunoreaction also labelled tenocyte-like cells in degenerative areas and fibres in regions of fat and collagen. Sensory innervation and vascularity are increased in tendinopathy. The evidence for innervation and vascularity of symptomatic rotator cuff tendon may aid the development of novel investigations and therapies in the management of patients with this ailment.