Orthopaedics - Veterinary Practice
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InFocus

Orthopaedics

HYPE or hope: which word will
best sum up the story of stem cell
therapies in veterinary medicine
over the coming years?

Leading veterinary orthopaedic
surgeon Professor John Innes gave a
guarded verdict of the future utility of
these much talked about techniques
in small animal patients in one of his
presentations at VetsNorth 2014.

In some respects, regenerative
medicine was progressing faster
and offered more promise in small
animals than in human patients, but
he had concerns about whether there
was sufficient understanding of the
underlying science to provide reliable
clinical results.

Moreover, he was worried that the
provision of veterinary services is
being driven too much by commercial
interests and that this might be so
damaging to the reputation of this
form of therapy that it never achieves
its potential.

Encouraging signs

Prof. Innes described a number of
studies carried out in university centres
around the world which have been
published in recent months.

Some have certainly shown
encouraging signs that stem cells,
usually harvested from bone marrow
or adipose tissue, can produce clinical benefits when delivered locally to
repair bone, cartilage or ligaments. Yet
other workers have experienced much
more disappointing results.

“That is because we don’t fully
understand the basic biology and I
would imagine that it may be decades
before we reach that stage. We have
to be careful about going straight into
the clinic and applying this technology
when it is poorly characterised, as that
way we might miss something,” he
said.

Certainly there is evidence that the
available techniques for harvesting,
purifying and applying stem cells can
be helpful in therapy in horses with
tendon injuries and in a few small-scale
studies in dogs.

Progress could be faster in small
animal than in human medicine as
there are fewer regulatory constraints
on the developing science. Dogs may
also provide a suitable model for
testing potential human therapies, he
noted.

But with current techniques, it
would seem unlikely that stem cell
therapies will enter routine use in
humans or animals. Prof. Innes pointed
out that using stem cells in treating
osteoarthritis, using autologous stem
cells derived from the patient’s own
cartilage, would require two separate
surgical procedures.

Together with the expense of
growing and purifying the cells, a
single treatment would probably
cost more than £20,000. Even if
cheaper methods can be developed for
veterinary use, the costs are still likely
to be prohibitive for most patients.

Not all the same

There was a widely-held belief that
all stem cells are the same but that is
far from the truth, he said. Different
cells from different organs vary in the
extent that they can undergo cycles of
development without differentiating
into a single form of adult cell. And
when the transformation does occur,
there are often limitations to the types
of cells that can be formed.

Disappointingly, those older patients
that are at greatest need of regenerative
medicine techniques will usually
produce smallest numbers and the least
vigorous stem cells, he said.

Prof. Innes believed that overly
optimistic and uncritical forecasts
of the potential value of stem cell
therapies have encouraged commercial
practices that he regards as suspect.
“There are companies that offer
parents the opportunity to bank the
stem cells contained in the dental pulp
of their child’s milk teeth for future
use. I think that is preying on people’s
fears and it is not something I would
choose to do if I was to have more
children.”

There was also the possibility that
stem cell treatment using either the
patient’s own cells or those from
donors could result in the development
of neoplasms or the transmission of infectious diseases. This was one
area that would have to be thoroughly investigated before these therapies are
offered for routine use, he said.

In questions, however, he said he
did not believe that there is a risk to
patients if lipoma cells are contained in
the adipose tissue extracted from their
own bodies and used as a source of
stem cells.

He believed that the processing
and purification process will remove
both normal fat cells and those from
normally benign fatty growths.

Amazing results

Prof. Innes accepted the findings of
Yorkshire practitioner Pred Prokic
who said he had witnessed “amazing
results” when treating a dog with
arthritic stifle joints with cells extracted
from its own fat deposits.

He said that in some of his
own patients treated with a similar
technique he had also seen impressive
clinical improvements. But there was
considerable variation in the results
achieved in different cases which
could not be easily explained and
histological samples showed that only
a small number of stem cells injected
into a joint migrated to the area of the
osteoarthritic lesion.

He wondered whether the clinical
benefits seen in such procedures were
a result of the cells having paracrine
effects – perhaps by releasing proteins
that mediate the inflammatory
process – rather than the physical
reconstruction of damaged tissue.

This would help explain the results
of earlier surgeons using injections of
whole blood into affected joints and
the more recent emergence of platelet
rich plasma as a treatment option in
osteoarthritis, he said.

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