Subsequently, two natural polymers (i.e., HA and alginate) can
be combined to form a desirable single system called the interpenetrating
polymer network (IPN) [33]. IPN is defined as the physically
or chemically cross-linked networks composed of two or more
polymers which can be fully or partially interlaced with each other
without any covalent bonds. In this network system, each polymer
can maintain its natural property, and synergistically enhance the
stability and mechanical strength of others [34–36]. In our previous
study [37], IPN composed of HA and sodium alginate (SA) was
prepared as a 3D chondrocyte delivery vehicle for cartilage repair.
It enhanced the mechanical properties, and promoted rabbit chondrocyte
attachment, proliferation and chondrogenic differentiation
in vitro. We found the most suitable ratio of HA/SA IPN for chondrocyte
delivery and delineated its physicochemical properties [37]. As
a continuous work, we have assessed the feasibility of applying the
optimized HA/SA composite scaffold for the proliferation and chondrogenic
differentiation of the hADSCs by performing in vitro and
in vivo studies.