Objective To explore the feasibility of a curcumin-loaded nanofilm using an encapsulation model to stabilize in
vivo chondrogenesis of stem cell-engineered cartilage. Methods Curcumin (CUR) with anti-angiogenic activities was loaded
into poly(L-lactide-co-caprolactone) (PLCL) and underwent electrospun process to produce a CUR/PLCL nanofilm, and a PLCL
nanofilm was identically prepared as a control group. The morphologies of PLCL and CUR/PLCL nanofilms were observed using
SLR camera and scanning electron microscope. The anti-angiogenic activity of CUR/PLCL nanofilm was evaluated through the
in vitro co-culture with human umbilical vein endothelial cells for 6 hours. In addition, rabbit-derived bone marrow stem cells
(BMSCs) were seeded into a porous gelatin scaffold and underwent chondrogenic culture for 3 weeks. The BMSC engineered cartilage was evaluated using SLR camera and histological staining. Finally, the BMSC engineered cartilage was embedded using
the CUR/PLCL nanofilm and implanted into nude mice subcutaneously for 6 weeks. The achieved samples were evaluated using
SLR camera, micro-CT, and histological staining examinations, aiming to distinguish chondrogenesis and ossification conditions.
Results In contrast to the white PLCL nanofilm, the CUR/PLCL nanofilm showed yellow color, whereas both nanofilms exhibited similar nano-scaled structure. The in vitro tube formation assay suggested that the CUR/PLCL nanofilm possessed enhanced
anti-angiogenic activity than PLCL nanofilm. A BMSC engineered cartilage tissue was successfully achieved via in vitro chon
drogenic culture of the BMSC-gelatin construct for 3 weeks, as evidenced by cartilage-like appearance in photograph, typical
lacunar structure and cartilage-specific extracellular matrix formation in HE staining, and positive stained glycosaminoglycan in
safranin-O staining. After subcutaneously implanted into nude mice for 6 weeks, the gross images indicated that the PLCL group
was obvious vascularized whereas the CUR/PLCL group was absent from vascular invasion. The micro-CT images suggested that
the PLCL group exhibited abundant bone trabecular structure but not in the CUR/PLCL group. The HE and saf-O/FG staining
further confirmed that the PLCL group showed typical bone trabecular structure and bone-specific matrix, and the CUR/PLCL
group displayed typical mature lacuna and cartilage-specific extracellular matrix. Conclusion CUR/PCL nanofilm could stabilize in vivo chondrogenesis of stem cell-engineered cartilage using an encapsulation model.
