Three-dimensional nano-architected scaffolds with tunable stiffness for efficient bone tissue growth

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Cellular Mechanobiology

Background:

• Orthopedic implant failure mechanisms remain unclear, with the bone-implant interface's micromechanical environment being crucial for stability.
• Understanding 3D scaffold mechanics' effect on osteointegration is limited by fabrication and characterization challenges.
• Existing research highlights 2D substrate stiffness's role in cell behavior, but 3D interactions are less understood.

Purpose of the Study:

• To investigate how the 3D mechanical environment of nanolattices affects bone formation and osteoblast response during early osteointegration.
• To determine the relationship between scaffold stiffness and cellular mechanosensitivity, including mineral secretion and cytoskeletal organization.
• To identify optimal scaffold stiffness ranges for enhanced osteoblast function and bone regeneration.

Main Methods:

• Fabrication of 3D polymer nanolattices using two-photon lithography (TPL) with controlled strut and pore sizes.
• Coating nanolattices with Ti/W and TiO2 for biocompatibility, followed by nanomechanical testing to determine stiffness (0.7-100 MPa).
• Seeding osteoblast-like cells (SAOS-2) and culturing them in mineralization media to assess intracellular f-actin, vinculin, and mineral secretions (Ca, P) over 12 days.

Main Results:

• The most compliant nanolattices (0.7 MPa) showed approximately 20% higher intracellular f-actin and 40% greater Ca and P secretion compared to stiffer scaffolds.
• Cellular responses on stiffer nanolattices were significantly less pronounced.
• A phenomenological model correlated scaffold stiffness with f-actin concentration, predicting an optimal range for osteoblast activity.

Conclusions:

• Three-dimensional scaffolds with stiffness similar to cartilage (0.5-3 MPa) and titania-coated surfaces may provide an optimal microenvironment for osteoblast growth.
• Osteoblast mechanosensitivity is significantly influenced by scaffold stiffness in a 3D context.
• Findings suggest potential for developing more effective and safer bone prostheses by tuning scaffold mechanical properties.