J Orthop Res. 2018 Jul 23. doi: 10.1002/jor.24112. [Epub ahead of print]

Initial cell plating density affects properties of human primary synovial mesenchymal stem cells.

Nakamura K¹, Tsuji K², Mizuno M³, Koga H¹, Muneta T^1,4, Sekiya I³.

Abstract

Synovial mesenchymal stem cells (MSCs) appear to be an attractive cell source in cartilage and meniscus regeneration because of their high proliferative and chondrogenic potentials. Two methods are used to culture synovial nucleated cells in the preparation of primary synovial MSCs. In one method, the cells are plated at low density to make cell colonies. In the other method, the cells are plated at high density. We investigated the effects of initial cell density on proliferation, surface markers and multipotentiality, including chondrogenesis in primary synovial MSCs. Human synovium was obtained from the knee joints of patients with osteoarthritis after total knee arthroplasty. Immediately after enzyme digestion, the synovial nucleated cells were plated in densities of 10³ , 10⁴ , or 10⁵ cells/60-cm² dish and cultured for 14 days. Proliferation, surface markers, chondrogenesis, adipogenesis, and calcification were examined in three populations. The cell colonies were distinct in the 10³ cells/dish group, faint in the 10⁴ cells/dish group, and obscure in the 10⁵ cells/dish group. The total number of cells /dish was positively related to plating density, whereas the fold increase was negatively related to plating density (n = 13). Among 12 surface markers, a negative relation to plating density was distinct in CD105. The cartilage pellet weight was negatively related to the initial plating density. The oil red-o positive area and alizarin red positive area were positively related to the initial plating density. The initial cell plating density affected the properties of primary synovial MSCs. Synovial nucleated cells proliferated better when plated at low density, and the synovial MSCs obtained by this method contained a high chondrogenic potential. This article is protected by copyright. All rights reserved.