Mesenchymal stem cells (MSCs) are proposed to be useful in cartilage regenerative
medicine, however, canine MSCs have been reported to show poor chondrogenic capacity.
Therefore, optimal conditions for chondrogenic differentiation should be determined by
mimicking the developmental process. We have previously established novel and superior
canine MSCs named bone marrow peri-adipocyte cells (BM-PACs) and the objective of this
study was to evaluate the effects of growth factors required for
in vivo
chondrogenesis using canine BM-PACs. Spheroids of BM-PACs were cultured in chondrogenic
medium containing 10
n
g/m
l
transforming growth factor-β1
(TGF-β1) with or without 100
n
g/m
l
bone morphogenetic
protein-2 (BMP-2), 100
n
g/m
l
growth differentiation
factor-5 (GDF-5) or 100
n
g/m
l
insulin-like growth
factor-1 (IGF-1). Chondrogenic differentiation was evaluated by the quantification of
glycosaminoglycan and Safranin O staining for proteoglycan production. The expression of
cartilage matrix or hypertrophic gene/protein was also evaluated by qPCR and
immunohistochemistry. Spheroids in all groups were strongly stained with Safranin O.
Although BMP-2 significantly increased glycosaminoglycan production, Safranin O-negative
outer layer was formed and the mRNA expression of COL10 relating to cartilage hypertrophy
was also significantly upregulated (
P
<0.05). GDF-5 promoted the
production of glycosaminoglycan and type II collagen without increasing COL10 mRNA
expression. The supplementation of IGF-1 did not significantly affect cartilaginous and
hypertrophic differentiation. Our results indicate that GDF-5 is a useful growth factor
for the generation of articular cartilage from canine MSCs.