Mesenchymal Stem Cells (MSCs) have been recognized for their ability
to differentiate into cells of different tissues such as bone, cartilage or
adipose tissue, and therefore might be of interest for potential therapeutic
strategies. These cells are induced to differentiate by growth factors
supplementation in culture medium that will trigger differentiation
in the desired cell type. Chondrocytes are responsible for maintaining
the extracellular matrix (ECM) integrity of articular cartilage. Chondrocytes
have been shown to release growth factors that can ultimately
induce chondrogenic differentiation of undifferentiated cells, for example
MSCs. It is well known that chondrocytes tend to de-differentiate
when in 2D culture, losing their ability to produce a rich ECM. In this
process occurs a shift from collagen type II production to collagen type
I, among other factors, giving rise to a fibrocartilage tissue. In order to
overcome this problem, several tissue engineering strategies have been
proposed, involving different combinations of cells, including the use of
co-cultures. The present work presents a co-culture strategy using
human articular chondrocytes and stem cells (Wharton′s jelly stem
cells) for cartilage-like tissue production. We aimed at assessing the
paracrine effect that chondrocytes may have on stem cells by co-culturing
directly both cells on the two faces of NFM. The aim is to allow
communication of the two cells communities by soluble factors
released, but not having direct contact between them. Polycaprolactone
(PCL) nanofiber meshes (NFM) were produced by electrospinning. The
NFM were further placed into inserts (two in each insert) in order to
allow seeding each type of cells in opposite faces of the NFMs. Cells
were isolated from human samples collected at the local hospital, under
donors’ informed consent. After cells expansion, chondrocytes were
seeded on the top of the NFMs, whereas stem cells were seeded on the
bottom of the NFMs. Controls were performed by seeding chondrocytes
or stem cells in NFM. For evaluation of cell viability, proliferation and
distribution within the scaffolds, DNA, Alamar Blue and SEM methods
were used. Chondrogenic differentiation was evaluated using histological
staining, glycosaminoglycan quantification, qRT-PCR and immunolocalization.
Cells kept viable along the experiment. Stem cells were
able to over express cartilage related genes such as aggrecan, sox9 and
collagen type II when compared to the undifferentiated controls. Articular
chondrocytes induced the chondrogenic differentiation of stem
cells and ECM formation. The obtained results showed that this new
strategy enables the development of new therapies for cartilage repair.
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