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

growth observed in-vitro.
5. RESULTS
Besides resembling the patterns predicted by the curvature-driven growth model, the
tissue distribution obtained in vitro in circular pores and on semi-circular channels
reveals the importance of the boundary conditions for tissue deposition. Although
surfaces have the same curvature in both cases, tissue follows a homogeneous
concentric growth in the circles, whereas interfaces tend to flatten on the semi-circular
surfaces (Fig.2A).
To compare quantitatively growth kinetics, the PTA is normalized by the initial area of
the pore (PA). Tissue growth is linear during the first two weeks of culture in the
circular pores, as already observed for convex shaped pores 9 . However, as a result of
surface flattening, tissue deposition in the channel is significantly slower and non linear.
A general slowdown of growth is also observed after 2 or 3 weeks of culture (Fig.2B).
Tissue stained after culture reveals cells organisation (Fig.2C). Nuclei are
homogeneously distributed all over the tissue whereas actin fibres have a higher density
and degree of alignment along the interface. Actin pattern resembles the fibrous
network predicted by the geometrical construction (Fig.2B).
Fig.2: Experimental and computational tissue growth behaviour obtained in circular
pores and semi-circular channels agree both qualitatively (A) and quantitatively (B).
Actin (green) and nuclei (red) distributions support the chord representation that
explains the curvature-driven behaviour of tissue growth (C). Such patterns can also be
observed in vivo during bone remodelling in osteons (top) [picture from Ron Shahar] 12
and hemi-osteons (bottom) [reproduced from Ref 13 with permission of Springer].
6. DISCUSSION
The present experimental and computational results show that geometry is a
determining parameter in biological processes involving tissue production and