Whole tissue
In order to incorporate the three main parts of the human
intestinal mucosa / enterocytes, mucus and the normal
microbiota / whole intestinal tissue can be used (63). Such
a model has been further developed to study adhesion to
resected human intestinal tissue (55), and can be used to
investigate the influences of intestinal diseases on the
adhesion of probiotics. Comparison with healthy tissue
may sometimes be difficult, since usually only small parts of
healthy tissue are resected together with the diseased tissue.
However, healthy material can be obtained when part of the
intestine is resected for reasons not directly related to
diseases, for example, extreme obesity. Because different
intestinal diseases have been shown to be associated with
differences in the composition of the normal microbiota
(64) and the composition of, for example, the mucus (65),
this may influence the adhesion to diseased intestinal
material as compared with the healthy intestine. At the
same time, however, it provides an opportunity to investigate
disease-dependent adhesion. Treatment of a patient
prior to surgery or biopsy sampling (e.g. prophylactic
antibiotic treatment and bowel cleansing) may also affect
adhesion. These practices differ between hospitals (55). The
use of ‘fresh’ material for adhesion studies is preferred, but
may not always be possible. It is therefore important to
validate the method of preservation; i.e. freezing in appropriate
buffer solutions.
This use of whole tissue for adhesion assays aims at
relatively short incubation times and does not investigate
any possible changes in the physiology or morphology
induced by the probiotic.