A pilot study of cells in human plantar fascia exposed to chronic ischemia due to atherosclerosis

Abstract

Objectives. The human plantar fascia (PF) is a tendon-like structure that some regard as a plantar aponeurosis. It provides attachment to muscles and supports the arch of the plantar side of the foot. In earlier studies on the histological structure of PF, chondrocytes were found within its dense connective tissue (CT), suggesting that the CT cells change in response to chronic conditions like diabetes mellitus (DM). This study aims to explore whether chronic ischemia of the CT, as seen in peripheral artery disease (PAD), results in chondrocyte differentiation from fibrocytes. Materials and methods. Forty-six paraffin-embedded blocks (2.0 x 0.5 cm) of the central part of the PF were obtained from amputated feet with PAD (N = 16), DM (N = 4), and acute conditions (AC, N = 3). Each sample was sectioned along the collagen fibers at a thickness of 3 µm and stained with H&E. Two visual fields per slide were examined using x10 objective lens of an OLYMPUS BX40F4 microscope, and images were captured with a digital camera. Measurements of the total count of cells and chondrocytes (if present) were taken, and the number of cells per mm² was calculated. Chondrocytes were identified by their round or oval nucleus, pale-stained cytoplasm, and basophilic territorial matrix. Results. The average area per investigated field was 315,235.8 µm². The average number of cells per mm² was 261.3 in the DM group, 218.7 in the PAD group, and 281.6 in the AC group (p > 0.05, Mann–Whitney U and t-test). Chondrocytes accounted for 28.5%, 14.5%, and 6.9% of cells in the DM, PAD, and AC groups, respectively. Significant differences were observed in chondrocyte percentage between the DM and AC groups (p < 0.05). Conclusions. A tendency that chronic ischemia causes chondrocyte differentiation from fibrocytes in PF was observed, statistically significant difference not achieved due to too few cases examined in the control group.