Stimulation of Aggrecan Synthesis in Cartilage Explants by Cyclic Loading Is Localized to Regions of High Interstitial Fluid Flow1

A cartilage growth mixture model for infinitesimal strains: solutions of boundary-value problems related to in vitro growth experiments

“…A homogeneous reference configuration may be reasonable for constructs grown from isolated chondrocytes or for explants harvested 15 from immature bovine joints, which are nearly uniform in tissue composition (Buschmann et al 1999). The governing equations presented in the appendix are linearized by assuming that the magnitudes of the solid matrix displacement vector, fluid density change, pore pressure, mass growth functions, and remodeling parameter to be order epsilon, and retaining only terms that are first order in epsilon (i.e., discarding all 20 higher order terms) in the governing equations.…”

“…The local continuity equations (A6) become 6 This follows the linearization approach of (Green and Naghdi 1970). 7 Eqn. (8) 1 is obtained after truncating the polynomial series representation of the exponential function in (A8).…”

“…It has been shown that for a dynamic unconfined compression protocol, nonhomogeneous proteoglycan mass deposition is best correlated with the spatial profile of relative fluid velocity, being least at the center of the specimen and increasing with 15 radial coordinate r (Buschmann et al 1999). Motivated by these findings, we consider a special case where the growth tensor components are zero at r=0 and linearly increasing with the radial coordinate r. Also, we restrict attention to the special case where the radial and circumferential growth tensor components are identical.…”

“…The type of nonhomogeneous growth that was chosen here was intended to 15 model the results of (Buschmann et al 1999) in which a dynamic compression loading protocol revealed that proteoglycan mass deposition was most closely correlated with the magnitude of diffusive velocity, increasing with radial position. The results predict that non-uniform growth leads to a nonhomogeneous specimen with a residually stressed solid matrix, in agreement with previous studies.…”

A multichamber fluidic device for 3D cultures under interstitial flow with live imaging: Development, characterization, and applications

“…In addition to promoting lymphatic capillary morphogenesis in vivo (Boardman and Swartz, 2003;Rutkowski et al, 2006), interstitial flow can stimulate blood and lymphatic endothelial cells (BECs and LECs) to organize into capillary-like structures containing lumen (Helm et al, 2005(Helm et al, , 2007Ng et al, 2004), at least partly due to the generation of morphogen gradients around the cells that lead to growth in the direction of flow (Helm et al, 2005). Interstitial flow also plays important roles in a variety of physiological and pathophysiological processes, including tumor cell invasion and metastasis (Fleury et al, 2006;Shields et al, 2007;Swartz et al, 2008), matrix remodeling and myofibroblast differentiation (Ng et al, 2005), and bone and cartilage remodeling (Buschmann et al, 1999;Evans and Quinn, 2006;Hayward and Morgan, 2009;Santos et al, 2009), to name a few. It is worth noting that physiological flows are generated by pressure gradients, even though cells may sense and respond to the actual flow velocities in terms of shear stresses.…”