Shell-core bi-layered scaffolds for engineering of vascularized osteon-like structures

Area of Science:

• Biomaterials Engineering
• Tissue Engineering
• Orthopedic Research

Background:

• Hierarchical cortical bone structure is crucial for bone function.
• Bottom-up assembly of osteon-like structures is a promising strategy for bone tissue engineering.
• Existing methods struggle to replicate the complex microarchitecture of natural bone.

Purpose of the Study:

• To develop a novel scaffold for creating vascularized osteon-like structures.
• To precisely control cell distribution for hierarchical bone formation.
• To mimic the Haversian canal function within engineered bone constructs.

Main Methods:

• Fabrication of a shell-core scaffold using a two-step approach: electrospinning and twin screw extrusion (TSE).
• Scaffold composition: helical outer shell of polycaprolactone (PCL) microfilaments and biphasic calcium phosphates (BCP), surrounding a hollow PCL nanofibrous core.
• In vitro culture of pre-osteoblasts (POBs) and endothelial cells (ECs) on the scaffold.

Main Results:

• Scaffolds with helical shell pitch >135 μm and BCP promoted POB proliferation and osteogenic differentiation.
• The nanofibrous core's luminal surface supported EC adhesion and formed a continuous endothelial lining.
• The engineered structures mimicked vascularized osteon-like units.

Conclusions:

• The developed shell-core bi-layered scaffolds offer a new technology for creating osteon analogs.
• This approach enables precise spatial control of bone and vascular cells.
• The findings contribute to advancing bone tissue engineering and regenerative medicine.