ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

load of 0.5 N) resulted in a 55 kPa interfacial shear stress without teZCC. A teZCC
thickness of 0.5 mm resulted in a shear stress drop to 40 kPa at the teZZC-hydrogel
interface (Fig 2BC).
Figure 2: Push-off test model. Load-displacement curve (A). Maximum shear stress at
the teZCC-hydrogel interface (B) and at the scaffold-teZCC interface (C) for a 1 mm
displacement with different teZCC thicknesses.
4.2 In vitro engineering of a ZCC
As previously described [6], a teZCC could be obtained in a hydrogel inducing an
increase in the elastic modulus from 0.16 MPa in the hydrogel to 1.5 MPa at the teZCC
position. After creating a hydrogel-trabecular bone construct and calcifying the interface
(teZCC was about 0.2-0.5 mm in thickness), the push-off test (similar setup as figure
1.A) showed an increase in peak load from 0.4 N to 0.8 N.
Figure 3: Load-displacement curve for the non-calcified and calcified interface.
The peak load was then used to find the maximum shear stress the construct could
sustain before failure. According to our model (Fig 2AB), without the teZCC, a
maximum shear stress of 55 kPa was obtained with a 0.4 N load. With a teZCC of 0.5
mm in thickness, a maximum shear stress of 60 kPa was obtained at the teZZC-hydrogel
interface with a 0.8 N load.