Abstract:
Poly(L-lactide-co-ε-caprolactone) (poly(LLA-co-CL)) meets many of the requirements of a scaffolding
material for bone tissue engineering, such as adequate biocompatibility, degradability, and tunable
properties. However, poly(LLA-co-CL) scaffolding tends to be hydrophobic and does not favor cellular
attachment and differentiation. The overall purpose of this research project was to improve the physical
and chemical properties of poly(LLA-co-CL) scaffolds to enhance biological responses. The modifying
effects were evaluated and characterized in vitro and in vivo. The hydrophilicity of the surfaces of
poly(LLA-co-CL) scaffolding was increased, either by blending with Tween 80, or coating with nanodiamond
particles (nDPs). Compared with pristine scaffolds, the modified poly(LLA-co-CL) scaffolds exhibited
reduced albumin adsorption and significantly increased the seeding efficiency of bone marrow stromal
stem cells (BMSC). Poly(LLA-co-CL)/3% Tween 80 scaffolds implanted subcutaneously in rats exhibited
significantly increased mRNA expression of Runx2 and de novo bone formation. BMSC-seeded into
poly(LLA-co-CL)/nDPs scaffolds were implanted into rat calvarial defects and live imaging at 12 weeks
disclosed significantly increased osteogenic metabolic activity. Micro-computed tomography, confirmed
by histological data, revealed a substantial increase in bone volume. Modifying the surface of poly(LLA-co-
CL) scaffolds to improve hydrophilicity promotes osteoconductivity and bone regeneration. Further studies
are needed to understand the immunogenic responses, because implantation of a biomaterial always
initiates an inflammatory foreign body reaction. Moreover, the next generation scaffolding technique (3DF)
may customize bio-inspired artificial extracellular matrices, incorporating optimal physical and chemical
surface properties to improve stem cell support.
