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Editorial
Endoscopic innovation through animal experiments: a new invitro platform
Department of Surgery, Institute of Digestive Disease, The Chinese University of Hong Kong
J Gastrointest Oncol 2011; 2: 59-60. DOI: 10.3978/j.issn.2078-6891.2011.017
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The development in endoscopy has been tremendous since
the conceptof inspecting inside human’s gastrointestinal
tractfirst introduced in 1806. Flexible video endoscope
became available with the advances in fiberoptics, image
processing and technologies in CCD. In 1970s, the
performance of sphincterotomy upon ERCP marked the
start of the era of therapeutic endoscopy (1). The concept
of en-bloc resection for early gastrointestinal cancers
withendoscopic submucosal dissection (ESD) adopted the
principles of surgery and applied through endoscopy using
innovative instruments (2,3). Natural Orifices Transluminal
Endoscopic Surgery (N.O.T.E.S.) became the next logical
step for the development of endoscopic surgery (4). The
concept of N.O.T.E.S. is to achieve surgical procedures
through the natural orifices of human body without skin
incisions. This revolutionary idea, however, cannot be
applied to human immediately as the feasibility, safety
and effectiveness of these procedures were not completely
understand. Animal model became a very important means
to establish the achievability of new endoscopic diagnostic
and therapeutic procedures (5). These in-vitro experiments,
however, were limited by the use of large scale animals
toaccommodate large diameter of an ordinary endoscope
which is at least 9mm. Establishment of a tumor model
in these large scale animal is extremely difficult when
compared to nude mice models.
Endoscopic diagnosis for gastrointestinal cancers had
evolved tremendously over the past decade. With the development of novel technologies including narrow band
imaging and autofluorescence imaging, the detection
of early gastrointestinal neoplasm is greatly enhanced
(6). Endoscopic diagnosis is evolving towards optical
histopathology, molecular and immunological imaging
(7,8). One of the important issues to enhance the advances
in these technologies is the effectiveness of visualizing
neoplastic or cellular changes. Animal model becomes
an essential tool forpreclinical investigations of these
technologies before its application in human patients.
Kiesslich et al observed the presence of epithelial gaps
between intestinal cells in a living mouse model and
correlated this finding to confocal observation of similar
gaps in human ileum (9). Though these gaps were identified
in living mouse small intestinal epithelium initially, these
were not observed in fixed and sectioned human small
intestine. This means that a living animal model is essential,
otherwise important features may not be detected even
using human cadaveric model.
In the current article, Anders et al reported the success of
using a new experimental model to allow the use of ordinary
clinical endoscopes to examine a small animal tumor model
(10). The tumor model was developed through injection
of cancer cell lines to 4 sites of cecal wall of rat through
laparotomy. A second laparotomy was then performed
23 days after the injection, and the growth of tumor
was confirmed upon opening of the cecum. Endoscopic
examination of the tumor was then performed while the
cecum was still perfused, hence confocal endomicroscopy
could be performed after intravenous administration
of 5% fluorescein. In previous mentioned animal model
examining gaps between small bowel mucosal cells, topical
spray of Acriflavine was used for staining. The current
model confirmed that intravenous contrast using fluoresein
is feasible and safe in animal.
The current model, however, cannot completely
simulate the clinical use of endoscopy to recognize gastrointestinal cancers. Normal endoscopy is performed
to differentiate neoplastic lesions from inside the
lumen of the gastrointestinal tract, while the current
model allows the endoscopic technologies to observe
tumors when the gastrointestinal tract is surgically
unbolted. Therefore, the effectiveness of screening and
recognition for early gastrointestinal neoplasia using novel
endoscopic technologies could not be fully simulated.
Moreover, the tumor utilized for this model is derived
fromrhabdomyosarcoma cell line. The feasibility of
using other gastrointestinal tract related cancer cell lines
necessitate further experiments.
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References
Cite this article as:
Chiu P. Endoscopic innovation through animal experiments: a new invitro platform. J Gastrointest Oncol. 2011;2(2):59-60. DOI:10.3978/j.issn.2078-6891.2011.017
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