The knee menisci have important roles in the knee joint. Complete healing of the meniscus remains a challenge in the clinics. Cellularity is one of the most important biological parameters that must be taken into account in regenerative strategies. However, knowledge on the 3D cellularity of the human meniscus is lacking in the literature. The aim of this study was to quantify the 3D cellular density of human meniscus from the osteoarthritic knee in a segmental and regional manner with respect to laterality. Human lateral menisci were histologically processed and stained with Giemsa for histomorphometric analysis. The cells were counted in an in-depth fashion. 3D cellular density in the vascular region (27 199 cells/mm3) was significantly higher than in the avascular region (12 820 cells/mm3). The cells were observed to possess two distinct morphologies, roundish or flattened. The 3D density of cells with fibrochondrocyte morphology (14 705 cells/mm3) was significantly greater than the 3D density of the cells with fibroblast-like cell morphology (5539 cells/mm3). The best-fit equation for prediction of the 3D density of cells with fibrochondrocyte morphology was found to be:
Density of cells with fibrochondrocyte morphology = 1.22 × density of cells withfibroblast-like cell morphology + 7750.
The present study revealed the segmental and regional 3D cellular density of human lateral meniscus from osteoarthritic knee with respect to laterality. This crucial but so far missing information will empower cellular strategies aiming at meniscus tissue regeneration. Copyright © 2015 John Wiley & Sons, Ltd.