Change in surface roughness by dynamic shape-memory acrylate networks enhances osteoblast differentiation
Erin M Lee1, Kathryn Smith2, Ken Gall3
1Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology, Atlanta, GA, USA.
Biomaterials
|October 7, 2016
Summary
Shape memory polymers dynamically change surface roughness, influencing osteoblast responses. This dynamic surface topography may enhance osseointegration of implants by mimicking natural bone healing processes.
Area of Science:
- Biomaterials Science
- Tissue Engineering
- Surface Chemistry
Background:
- Microscale surface roughness on titanium implants enhances osseointegration by promoting osteoblast differentiation.
- Osteoblast proliferation is generally higher on smooth titanium surfaces compared to rough ones.
- This study leverages these contrasting effects by developing a dynamic surface material.
Purpose of the Study:
- To develop and evaluate a shape memory polymer with time-dependent surface topography changes.
- To investigate the impact of dynamic surface roughness recovery on osteoblast response in vitro.
- To assess the potential of this dynamic material for improving implant osseointegration.
Main Methods:
- A shape memory (meth)acrylate copolymer was synthesized with thermomechanical properties enabling dynamic surface changes.
- Rough topographies mimicking clinical titanium surfaces (machined, acid-etched, grit-blasted) were created using soft lithography.
- Surfaces were compressed to smooth and allowed to recover roughness within 24 hours under cell culture conditions.
- Osteoblast responses including cell number, alkaline phosphatase specific activity (ALP), osteocalcin (OCN), osteoprotegerin (OPG), and vascular endothelial growth factor (VEGF) were analyzed under static and dynamic conditions.
Main Results:
- Under static conditions, polymer surface roughness did not affect osteoblast number, ALP, OPG, or VEGF, but increased OCN on the grit-blasted mimic.
- Under dynamic conditions, DNA content decreased, while OCN and OPG increased on the compressed grit-blasted polymer compared to static surfaces at 3 days.
- Osteoblast responses were sensitive to the time-dependent topographical changes of the polymer surface.
Conclusions:
- Shape memory polymers can create dynamic surface topographies that modulate osteoblast behavior.
- The time-dependent surface change from smooth to rough influences specific osteoblast responses like OCN and OPG production.
- Dynamic surface roughness using shape memory polymers presents a promising strategy for enhancing osseointegration of biomedical implants.
