annual report - O'Brien Institute

expression is increased following trauma, and in which
cells it is expressed. We found that, as in animals, LIF is
expressed within injured human nerves by a variety of
cells, including Schwann cells and inflammatory cells, and
that chronic neuromas continue to contain high levels of
LIF for several years. These data suggest further
examination is warranted to determine whether continued
expression of LIF in unhealed injured nerves promotes or
exacerbates the development of neuromas, or is simply a
response to continued ‘trauma’.
LIF and Schwann cell survival
Schwann cells are cells which line the nerve fibres and
play a major role in promoting nerve survival and
regeneration after injury. They are the major source of
LIF, and GDNF, at the injury site. Our own research has
shown that Schwann cells require LIF for survival in
culture, and that when we blocked LIF function within the
entubulation repair site the survival of Schwann cells was
markedly reduced. This suggests that one of the actions of
LIF following nerve trauma is to prevent injury-induced
cell death.
Role of NOS 2 in nerve regeneration
The nitric oxide producing protein NOS 2 is thought to
play a role in blood vessel formation. It is also thought to
be regulated in some tissues by LIF expression. We used
the NOS 2 inhibitor AET administered for one month
following nerve repair to determine whether NO-derived
from NOS 2 played a role in nerve regeneration in our
model, and whether the addition of LIF at the time of
repair could overcome the effects of NOS 2 inhibition.
When NOS 2 production is blocked with AET, in addition
to repairing the nerve stumps, re-vascularisation and nerve
regeneration are delayed within the silicone tube for up to
4 weeks. Addition of LIF to the tube at the time of repair
failed to overcome the effects of the AET. This series of
experiments suggest that nitric oxide is important to
angiogenesis and subsequent axon growth and may be
required for the action of LIF.
The treatment of pain resulting from a neuroma
Neuromas are bulbous swellings which occur at the cut
end of nerves, and these can become extremely painful,
resulting in neuropathic pain and sometimes loss of work
and, in extreme cases, suicidal tendencies. We are
investigating the characteristics of the neuron population
and local resident cells which contribute to the neuroma.
Once a nerve is injured or cut and not repaired, a neuroma
bulb forms at the cut end and persists for the life of the
nerve. We have now shown that many uninjured nerve
fibres grow into this end bulb neuroma, in addition to the
injured nerves. We have commenced a very detailed study
of motor nerves cells before injury, and after neuroma
formation and will compare the effects of this procedure
on the contralateral uninjured nerve cells.
Alternative nerve repair methods
In some circumstances it is not possible to repair an
injured nerve branch by using the parent nerve and so an
unrelated healthy nerve is used instead. Two methods of
joining the injured nerve to the healthy nerve are possible.
In the first, the healthy nerve is partially cut through and
the ends of the injured nerve fibres are sutured to the cut
ends of the healthy donor nerve fibres (end-end repair). In
the other method, the injured nerve is sutured to the side of
the uninjured nerve (end-side repair). We have shown that
both these techniques result in a significant return of
function to the denervated muscles. However, the end to
end repair results in decreased function of the donor
“muscles” whereas these muscles are spared by using end
to side repair. Using a nerve tracer method, we determined
that recovery of the denervated muscles is mediated by
regeneration from nerve cells in the donor nerve and not
from of the original nerve cells.
When the distal stump of a severed nerve branch is
rejoined to the parent nerve at a site distant to the point of
severence, the denervated muscle regains some of its
original function. We have shown that a number of nerve
fibres grow down the parent nerve in newly formed tracks
rather than joining the existing tracks of nerves. These
nerve tracks originate at the level of the branch nerve
injury and most likely include some of the original cut
branch nerves fibres.
Helen M Schutt Vascular Research
Laboratory
Senior Scientists: Geraldine Mitchell, Peter Vadiveloo.
Clinical Research Fellow: Tony Penington.
Members of the Laboratory:
Angela Arvanitis, Mirna Boujaude, Rob Donato, Tanya
Harkom, Peter Meagher, Wayne Morrison, Rosalind
Romeo, Arthur Smardencas, and Debra Zafiropoulos.
...and Major Collaborators:
Brain Cooke d , Alastair Stewart a
aDepartment of Pharmacology, University of Melbourne
dDepartment of Microbiology, Monash University,
Clayton, Vic.
Blood vessel biology
Successful outcomes for surgery depend upon a good
blood supply to nourish repaired and transplanted tissue.
In this laboratory we are trying to get a better idea of how
blood vessels work, and how to manipulate blood vessels.
The knowledge generated from this work will not only
impact in areas of surgery but will also be relevant to
diseases such as cancer, arthritis and atherosclerosis since
changes in blood vessel growth and shape are important
features of these diseases.
Angiogenesis
The process of new blood vessel formation is called
angiogenesis. Until recently there has not been a clinically
relevant experimental model. The scientists and surgeons
at BOBIM have now developed such a model in rats and
mice. This is an important step since we can now use the
Director’s Report
Bernard O’Brien Institute of Microsurgery
Director
Professor
Wayne Morrison,
MD, BS, FRACS
Reconstruction following injury, tumour
resection, burns or congenital deformity
involves the transfer of tissues from one
part of the body to another. Virtually every body
part or tissue is capable of being transferred, e.g.
skin, muscle, bone and joints, nerves, fat, or
composite structures such as toes, scalp, etc. At
the Bernard O’Brien Institute research was
originally directed towards the role of
microsurgery in this process of tissue transfer.
Many of these techniques are now in common
use throughout the world and for this reason our
research is moving into the new frontier of tissue
engineering. This is a natural progression in the
sophistication of reconstructive techniques and of
microsurgery where only miniscule amounts of
the patient’s tissues are required to manufacture
the derived product. Microsurgery plays an
integral role in the process, firstly by supplying
the core vascular pedicle on which the tissue is
grown and then, if need be, in transferring the
product to the desired site for reconstruction.
Tissue engineering demands collaborations with
experts in several fields, especially cell culture
including stem cells, matrix biology, vascular
biology and bioengineering. We are very
fortunate to have in Melbourne many experts in
these fields who are generously contributing their
ideas. Tissue engineering offers the potential to
repair defects without the need to sacrifice other
areas of the body. It is an alternative to free tissue
transfer, artificial prostheses and organ and tissue
transplants.
MICROSURGERY
FOUNDATION
The Institute also has a major interest in nerve
repair following injury and in parallel with the
pain management service under the direction of
Dr Andrew Muir is interested in nerve pain,
especially neuroma formation. Research
includes the development of neuroma models
and studies mapping the sources of nerve fibres
which migrate into developing neuromas.
Studies have shown in human neuromas that the
growth factor (leukaemia inhibitory factor) is
abundantly produced. The role of this growth
factor in nerve repair and in pathological
processes is being investigated. The Schwann
cell which forms a sheath around nerve fibres is
a major producer of this growth factor and other
factors involved in the maintenance of nerve
function and in repair processes following
injury. Much of our research is directed towards
understanding the behaviour of this cell.
Injury to tissues following interference with
blood supply (ischaemia) has particular
relevance to our clinical work which involves
reattachment of amputated parts and the
transferring of tissues from one part of the body
to another. Investigations understanding the
nature of this injury and methods to minimise
its effect have been a long time interest in our
laboratory.
Inflammation is a fundamental body response to
injury and is integral to the repair process.
Macrophage function is one of our special
interests and research continues into the
molecular mechanisms which activate
macrophages.
Scarring following injury is a major source of
morbidity and compromises the results of
operations, particularly in organs which require
movement for function, such as the hand. We
are investigating agents which prevent collagen
formation and are hopeful that these will have a
role in reducing the morbidity associated with
injury and surgery.
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