Evaluation of Villus Synovium From Unaffected Metacarpophalangeal Joints of Adult and Juvenile Horses

Simone Della Tommasa; Karsten Winter; Johannes Seeger; Ingo Spitzbarth; Walter Brehm; Antonia Troillet

doi:10.1016/j.jevs.2021.103637

Evaluation of Villus Synovium From Unaffected Metacarpophalangeal Joints of Adult and Juvenile Horses

J Equine Vet Sci. 2021 Jul:102:103637. doi: 10.1016/j.jevs.2021.103637. Epub 2021 Apr 29.

Authors

Simone Della Tommasa¹, Karsten Winter², Johannes Seeger³, Ingo Spitzbarth⁴, Walter Brehm⁵, Antonia Troillet⁵

Affiliations

¹ Deparment for horses, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany. Electronic address: della.tommasa@vetmed.uni-leipzig.de.
² Institute of Anatomy, Medical Faculty, Leipzig University, Leipzig, Germany.
³ Institute of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany.
⁴ Institute of Veterinary Pathology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany.
⁵ Deparment for horses, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany.

PMID: 34119205
DOI: 10.1016/j.jevs.2021.103637

Abstract

Horses are a widely accepted model for osteoarthritis (OA) research. Synovial tissue sampling is commonly used in studies to evaluate and grade the progress of OA or to assess treatment effects. Synovial explants play an important role in ex-vivo studies, increasingly replacing the use of living animals. To understand histomorphological changes in the process of joint-related diseases such as OA, detailed information about histomorphometric parameters of unaffected synovial villi is necessary. The objective of the present study was to evaluate the mean width of the intimal synovial lining and its cellularity as well as the vascularization of the subintimal layer in juvenile and adult horses not affected by a joint-related disease. One hundred synovial samples from both metacarpophalangeal joints from 25 horses (one day to 24 years old) were collected to evaluate the following parameters on digitalized hematoxylin-eosin stained samples: Width of intimal synovial lining measured by the distance from the inner joint surface to the subintimal layer; density of the cells making up the intimal synovial lining by counting cell nuclei; vascularization of the subintimal layer measured by the number and size of vessels in relation to the subintimal area. The median width of the intimal lining did not differ among juvenile (22.34 µm) and adult (23.34 µm) horses. The cellularity of the intimal lining was significantly lower in juvenile (one cell/143.8 µm²) than in adult (one cell /188.7µm²), (P < .001) horses as well as the density of blood vessels per mm² within the subintimal layer (juveniles 1/mm² vs. adults 0.05/mm²), (P < .001). This study provides morphometric data regarding synovial intimal width, intimal cellularity, and vascularization of equine synovial villi of unaffected horses. For future studies, age-related characteristics should be taken into consideration when synovial tissue samples are used for in-vivo and in-vitro studies.

Keywords: Histomorphology; Horse; Metacarpophalangeal joint; Synovial membrane; Synoviocytes.

MeSH terms

Animals
Duodenum
Horse Diseases*
Horses
Joint Diseases* / veterinary
Metacarpophalangeal Joint
Osteoarthritis* / veterinary
Synovial Membrane