Publicado em : J Tissue Eng Regen Med 2014; 8 (Suppl. 1)Introduction: Osteochondral defect (OCD) regeneration presents major
challenges in orthopedics. Since healing of cartilage and bone should
be simultaneously considered, ideal scaffolds should be those that can
mimic both tissues properties. In this study, bilayered silk and silk-nano
calcium phosphate (Silk/Silk-NanoCaP) scaffolds with tailored
mechanical properties were developed for OCD tissue engineering
application.
Materials and methods: Aqueous silk solution (16%) was prepared.1
Nano calcium phosphate particles (16%) were synthesized in the silk
solution (Silk-NanoCaP).2 The bony layer was prepared by addition of
NaCl particles (500–1000 lm) into the Silk-NanoCaP suspension. After
drying for 2 days and salt-leaching overnight, silk solution was added
on top of the bony layer using the same procedure to produce the chondral
layer. The !nal scaffolds were evaluated through in vitro culture of
rabbit bone marrow stromal cells (RBMSCs) for 2 weeks, and in vivo
implantation in a rabbit knee OCD for 4 weeks.
Results: The RBMSCs cultured in the scaffolds presented increasing
viability from day 1 to day 7 by MTS assay. Good adhesion and migration
of the RBMSCs in the scaffolds were achieved, as observed under
the scanning electron microscope. Cell proliferation was observed from
day 7 to day 14 as determined by DNA quanti!cation. The bony layer
induced higher alkaline phosphatase level as compared to the chondral
layer, in osteogenic condition. Histological analysis (H&E) showed that
the bilayered scaffolds integrated well with the host tissue, after
4 weeks of implantation in a critical size OC defect (Fig. 1). Abundant
new bone formation was detected in the Silk-NanoCaP layer. Cartilage
regeneration occurred in the silk layer.
Discussion and conclusions: The bilayered scaffolds favored the attachment,
proliferation, and differentiation of RBMSCs. The bony layer of
the bilayered scaffolds possessed osteoconductive properties. The bilayered
scaffolds were biocompatible in vitro and in vivo. These scaffolds
also induced both subchondral bone regeneration and supported cartilage
regeneration, thus showing great promise in OCD regeneration.
Acknowledgments: The authors thank FCT projects Tissue2Tissue and
OsteoCart, and the FP7 Programme POLARIS. Yan LP was awarded a
FCT PhD scholarship. Investigador FCT program (IF/00423/2012) and
(IF/00411/2013) are also greatly acknowledged.
Disclosure: The authors declare that there is no con"ict of interest
