This study investigated alternative subcutaneous port placements for cerebrospinal fluid (CSF) sampling in chair-restrained cynomolgus monkeys. Three monkeys had intrathecal catheters implanted connecting to ports placed in different subcutaneous regions: under the shoulder blade (standard technique), in the thoracolumbar region, or in the sacral region. CSF collection was most successful from the sacral port placement, allowing for easier needle insertion and fixation while the monkey was restrained. The sacral port placement seems most promising for fast and easy CSF collection in restrained monkeys.

1. Introduction
Intrathecal infusion via the lumbar route represents an accepted while specialized
clinical route for drug delivery in humans (Tuner, 2003). Cerebrospinal fluid (CSF)
sampling from both the lumbar location and the ventricle system of the brain of
cynomolgus monkeys (Macaca fascicularis), the predominant nonhuman primate
(NHP) species in preclinical safety assessment, is frequently required during the
conduct of regulatory studies for assessment of inflammatory cerebral conditions.
The CSF can be used as a diagnostic aid in the assessment of inflammatory
conditions involving the brain, spinal cord, and meninges. However , for the majority
of these studies, CSF for bioanalysis, clinical chemistry (Deisenhammer, 2006;
Hambleton 1981) as well as cell counts needs to be collected at multiple time
points within few days. Sampling using spinal needle (Pencan Paed®: 25G, 50 or
25 mm, B. Braun Melsungen AG, Melsungen, Germany) on sedated animals is
limited to three occasions within the first 24 hours, hence limiting the ability for a
detailed evaluation. Therefore, port catheter systems are routinely implanted to
establish a constant access system either to the lumbar C SF or to the ventricle
system of the brain (Figure 1). This study was initiated to investigate alternative
subcutaneous (s.c.) port placements and their practical ability for easy C SF
withdrawal when using a chair-restrained monkey.
Materials and Methods
In this study, three female cynomolgus monkeys (~3.5 kg) were implanted (L2-L3)
using MID-LOVOL port (Solomon Scientific, USA), connected to a 3FR intrathecal
PU catheter. To compare our established technique of s.c. port placement under
the shoulder blade, the MID-LOVOL port was implanted in the est ablished way, in
the thoraco-lumbar region (animal B; Figure 2a) and in the region of the s acrum
(animal C; Figure 2b).
The animals were anesthetized using medetomidine and (S)-ketamine, shaved in
the region of the back and finally the skin was disinfected. Furthermore, the animal
received pain treatment and antibiotics. Surgical drapes were used to ensure a
sterile/aseptic environment. After localization of the intervertebral space L2/ L3 a
17G Tuohy needle was inserted until a positive C SF flow could be observed.
A 3Fr PU catheter was pushed through the needle until the catheter tip reac hed
the region of the thoraco-lumbar section. A small incision was made to prepare a
small pouch for the catheter, with the needle removed afterwards. The catheter was
secured using a Chinese-finger-trap suture and a small pocket was prepared in the
designated area for the port. After the catheter was tunneled to the poc ket, it was
connected to the port and secured using non-resorbable suture material. After all
wounds were closed the anesthesia was stopped using atipamezole. To ensure the
patency of the system it was flushed every three days in the first four weeks after
surgery with 0.5 mL artificial CSF, beginning on the day of surgery. On day 14, 17,
20, and 23 after surgery a Huber needle was used for C SF collection, while the
trained animals were placed in a restraint c hair.
Results
There were no adverse clinical signs, body weight c hanges, clinical pathology or
neurological findings directly after surgery in all three animals. Directly after surgery ,
successful CSF collection could only be performed in animal C. Overall C SF
collection was possible on single occasions for all animals for more than three
months, but in animal C the highest amount of C SF could be collected and the
highest flow of CSF was observed. The port position of this animal proved to be an
advantage for needle insertion/fixation, hence CSF collection in the restraint chair.
Conclusions
In conclusion, port implantation under the shoulder blade, in the thoraco-lumbar
region as well as in the region of the s acrum, is possible. Attention must be given
to the anticipated CSF sampling or dosing regimen, as chair restraint (bolus or
short-term infusion) and back-pack infusion over 24 hours require different s.c.
port positions.
Implantation of the port in the area of the s acrum seems to be the most promising
approach for fast and easy CSF collection.
Surgical Alternatives for Multiple CSF Sampling in Conscious Cynomolgus Monkeys:
A Novel Approach
J. Sternberg, S. Korte and C. Rose; Sponsor: G.F. Weinbauer
Covance Laboratories GmbH, Münster, Germany
#2044
Figure 1. X-ray scan from an intraventricular port implanted animal
showing the ventricle system of the brain via contrast medium.
1a
1
Figure 2a. MID-LOVOL port
implanted in the
thoraco-lumbar region (Animal B).
Figure 2b. MID-LOVOL port
implanted in the region
of the sacrum (Animal C).
2a 2b
References
Deisenhammer F., Bartos A., Egg R., Gilhus N.E., Giovannoni G., Rauer S., Sellebjerg F ., 2006:
Guidelines on routine cerebrospinal fluid analysis. Report from an E FNS task force.
Eur. J. Neurol. 13: 913-922.
Hambleton P., Baskerville A., Wade J.J., Bailey N.E., 1981: Some normal clinical chemistry
values for cerebrospinal fluid of the cynomolgus monkey, Lab. Animals 15:181-186.
Turner, MS, 2003: Intrathecal drug delivery 2002, Act a Neurochir, 87:29-35.

2. Presented at the
52nd Annual SOT
Meeting and ToxExpo™
San Antonio, Texas
10–14 March 2013
#2044
Surgical Alternatives for Multiple CSF
Sampling in Conscious Cynomolgus
Monkeys: A Novel Approach
J. Sternberg, S. Korte and C. Rose; Sponsor: G.F. Weinbauer
Covance Laboratories GmbH, Münster, Germany
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