Segmental characterization of the cellular density of human knee meniscus

Meniscus is a fibrocartilaginous tissue that has an important role in biomechanics
of the knee joint. Fibrochondrocytes and fibroblast-like cells
are the two main cell populations present in the meniscus. Meniscus is
distinguished into two regions: avascular and vascular region. Cellularity
varies within the human meniscus, specifically between avascular
and vascular regions of the meniscus, but also between anterior, medial
and posterior parts. Cellularity is one of the important characteristics
that should be considered in tissue engineering and regenerative medicine
strategies. The aim of this study is to calculate the 3D cell density
of human meniscus using histological slides. Meniscus tissues obtained
from donors are prepared into Giemsa stained histological slices with a
thickness of 30 lm. Slices are grouped by their anatomical location into
three parts: anterior, medial and posterior. Cells in the defined areas of
avascular and vascular regions are counted either as fibrochondrocytes
or as non-fibrochondrocytes using a stereomicroscope. 3D cell densities
of different region and parts of the meniscus are estimated by calculating
the number of the cells found in unit volume. The initial results
show that the 3D cell density is around 8000 cells/mm3 in vascular part
that is the almost double of the density in avascular part. Chondrocytes
take up more than the half of the total cell amount in avascular part,
and less than the half in the vascular part. This work aims to contribute
to the knowledge of cellularity of human meniscus and facilitates
the development of more efficient strategies for meniscus tissue
engineering. The authors thank the financial support of the MultiScale-
Human project (Contract number: MRTN-CT-2011-289897) in the
Marie Curie Actions—Initial Training Networks.