hepatic transporter proteins can be increased with the addition of

perfusion, while key junctional proteins such as claudin 2 are

retained with specific membrane staining in perfusion (Fig. 5).

This demonstrates the potential benefits of using such a system

for the culture of HepG2 hepatic models.

The intestine represents another organ subjected to mechanical

cues in vivo. The intestinal mucosa is exposed to peristaltic move-

ment of food substances at the apical lumen as well as basolateral

vascularization. Intestine models perfused within the bioreactor

system exhibit physiological parameters that more accurately repre-

sent the in vivo microenvironment of the small intestine compared

to that of static culture. Under dynamic conditions, the epithelial

cells appear to form villus–crypt-like architecture. Longer-term

perfusion results in a greater degree of cellular projection, as

shown by the histological data (Fig. 6). Visualization of Ki67-

positive cells by immunofluorescence staining reveals proliferative

cells are restricted to the basal area of the villus-like structures like

that of the in vivo environment (Fig. 7). Epithelial polarization at

the surface of the villus-like structures is evident and junctional

complexes form, as demonstrated by E-cadherin expression

(Fig. 7). Fibroblasts within the Alvetex^® Scaffold adopt a myofi-

broblast phenotype as a result of perfusion, as shown by positive

alpha smooth muscle actin staining. Perfusion of intestine models

illustrates the potential of the bioreactor system in simulating an

improved growth environment enabling more physiologically rele-

vant tissue morphogenesis.

Fig. 5 Immunofluorescence staining of static and perfused 3D HepG2 models. The transporters MRP2 and

MRP3 show distinct membrane staining, with an increase in perfusion. The tight junction protein claudin

2 exhibits a uniform staining of the cell membranes in both 3D static and 3D perfused culture methods. Scale

bars: 50 μm

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Henry W. Hoyle et al.