Background: Although autogenous bone implantation is considered to be
the gold standard for the reconstruction of bone defects, this approach remains
challenging when treating extensive bone defects (EBDs). Therefore, artificial
materials (AMs) such as artificial bone and scaffolds are often used for treating
EBDs. Nevertheless, complications such as material failure, foreign body
reaction, and infection are common. To overcome these issues, we aimed to develop
a new treatment for an EBD using scaffold-free adipose-derived stromal cells
(ADSCs) to fabricate chondrogenic/osteogenic-induced constructs without AMs.
Methods: ADSCs were obtained from the subcutaneous adipose tissue of
8-week-old female Wistar rats (n = 3) and assessed to determine their potential
for multilineage differentiation into adipocytes (Oil Red O staining),
chondrocytes (hematoxylin and eosin, Alcian blue, and Safranin O staining), and
osteoblasts (Alizarin red and von Kossa staining). Spheroids (n = 320), each
containing 3.0 10 ADSCs, were then used to fabricate
scaffold-free cell constructs using a bio-3D printer with a needle array. The
spheroids and constructs were stimulated with induction medium to induce
chondrogenic and osteogenic differentiation. The induced cartilage- and bone-like
constructs were finally evaluated using micro-computed tomography (CT) and
histological analysis. Results: The collected ADSCs were capable of
trilineage differentiation, and were successfully used to produce scaffold-free
constructs. The fabricated constructs (n = 3) exhibited equivalent strength
(load, 195.3 6.1 mN; strength, 39.1 1.2 kPa; and stiffness, 0.09
0.01 N/mm) to that of soft tissues such as the muscles in the uninduced
condition. In chondrogenic induction experiments, Alcian blue and Safranin O
staining confirmed the differentiation of the constructs into cartilage, and
cartilage tissue-like structures were produced. In the osteogenic induction
experiment, Alizarin Red and von Kossa staining showed calcium salt deposition,
and CT images confirmed the same calcification level as that of the
cortical bone. Conclusions: Scaffold-free constructs consisting of ADSCs
without an AM were fabricated, and cartilage- and bone-like tissues were
successfully generated, demonstrating their potential for bone reconstruction.