Segmental characterization of the cellular density of human knee meniscus

The meniscus is found between femoral condyles and tibial plateau in the knee, and it has crucial roles in the joint biomechanics. In the absence of meniscus, degenerative changes develop within the knee and for this reason it is important to preserve the meniscus. Since complete healing of meniscus is not fully achieved in the clinics yet, there is a need to develop advanced tissue engineering and regenerative medicine (TERM) strategies. Cellularity is one of the important parameters in the TERM strategies as cells are responsible for the extracellular matrix production and tissue regeneration. In the last few years there have been great achievements in meniscus tissue engineering, but still there is a poor knowledge on meniscus biology. The objective of this work is to characterize the 3D cell density throughout human meniscus in a regional and segmental manner. Six human lateral meniscus tissues were processed into Giemsa stained histological slices. The cells were counted in an in-depth fashion as either fibrochondrocytes or as fibroblast-like cells respectively based on their roundish or elongated morphology using Olympus BX51 Microscope and Stereo Investigator software from MBF Bioscience. 3D cell densities throughout the meniscus were obtained with the calculation of the number of the cells per unit volume in the vascular and avascular regions of the anterior, mid-body, and posterior segments. The density of fibrochondrocytes is 14,705 cells/mm3, which is more than the double of the density of fibroblast-like cells that is 5,539 cells/mm3. Vascular regions have the mean 3D cell density as 27,199 cells/mm3, and the avascular regions 12,820 cells/mm3. This study brought the knowledge on the density and distribution of cells in the meniscus in a segmental and regional manner, and the results are important for the development of advanced cell-based TERM strategies for meniscus.