161- Do frequent agitations of cell suspensions in the tube before
drawing up into the syringe for intraperitoneal injection. This
will make a homogeneous cell suspension, which is important
for injection of equal number of cells into each mouse. Injection
of equal number of cells into each mouse is very important for
reproducible results. - Frequent hair clipping every few days may be necessary for
SCID mouse depending on the growth of the hair.
Subcutaneous tumor xenografts can also be done in athymic
nude mice where hair clipping is not necessary. - Clean and sterilize the inoculation area of the mice with etha-
nol and/or iodine solutions before cell injection. Draw the
cells into a syringe without a needle. Using a needle causes a
strong negative pressure that can cause cell damage and lysis.
Try to create a single bubble of subcutaneous cells by slow
injection and avoid too much spread of cells. - During tumor measurements, take the greatest longitudinal
diameter (length) and the greatest transverse diameter (width). - Choosing an appropriate needle size (25 G × 5/8) for intra-
peritoneal cell injection will facilitate inserting the entire length
of the needle that may prevent leaking of cells outside or into
the abdominal wall. Leaking of the cells into the abdominal
wall may lead to the local tumor formation and will jeopardize
the whole experiment. Injecting large volume as 1 ml of cell
suspension may decrease the number of cells leaked into the
abdominal wall, which may decrease the rate of local tumor
growth. The number of cells required for having an optimum
time frame for mouse survival study may vary widely depend-
ing on the cell types and a pilot study should always be done
with different cell lines of varied origin before choosing ideal
cell lines for therapeutic interventions (see Table 2 ) [ 12 ]. - Do injections in the lower right quadrant of the abdomen to
avoid damage to the urinary bladder, the cecum, and other
abdominal organs. Appropriate restrain with head-down posi-
tion of the mouse during injection will also move the gut away
from the injection site and will prevent damage to the gut. - During intraperitoneal injection, it is helpful to turn the needle
so that the bevel points face up and the numbers on the syringe
barrel can be read. - Negative pressure ensures that the needle is in the peritoneal
cavity and not in a blood vessel. - Ascites, jaundice, loss of ability to ambulate and inability to
drink or feed are good indicators for euthanizing mice. - A good animal survival period (1–3 months) is necessary for
possible therapeutic interventions in an animal survival study.
Xenograft Models of Esophageal Adenocarcinoma