assembly and disassembly. Preliminary research at the University of Zurich
has yielded promising results for alleviation of joint pain.
IRAP/ACS has also been suggested as a potentially effective biological
treatment for tendon and ligament injury with possible anabolic effects
mediated by growth factors. No clinical data are available to support these
data, but two experimental studies have cast doubt on these claims. Dahlgren
et al. (2007) found no differences for the levels of IGF-I, FGF-2 and TGF-b1
between normal serum and Orthokine (ACS). Although treatment of tendon
explants with both normal serum or Orthokine generally increased gene
expression compared to 10% FBS, there were no significant differences
between normal serum and Orthokine for expression of collagen type I, type,
III, COMP, or MMP13. Another study of equine superficial digital flexor tendon
explants exposed to IL-1beta stimulation found that IRAP/ACS was not able to
suppress PGE2 production by the explants, unlike traditional antiinflammatory agents like dexamethasone, phenylbutazone, indomethacin and
firocoxib (Smith et al. 2012 - unpublished data). In conclusion, not only are the
clinical data for use of IRAP in tendon injury lacking, but the experimental data
fail to show any beneficial effect.
Platelet-Rich Plasma (PRP)
Recently, platelet-rich plasma/concentrate has gained popularity in the
treatment of tendon, ligament and joint injuries. PRP contains high levels of
growth factors sequestered in platelets, most notably platelet-derived growth
factor (PDGF) and transforming growth factor beta (TGF-beta1) but also
vascular endothelial growth factor (VEGF) which promotes neovascularisation
in soft tissues. It is not known whether these growth factors are optimal for
ligament and joint healing but they have been demonstrated to have anabolic
effects in vitro on many cell and explant systems derived from tendon and
ligament and are therefore logical factors to consider for therapy. Results of
in vitro studies indicate that equine PRP has an increased concentration of
growth factors, compared with that of whole blood or plasma. When incubated
with superficial digital flexor tendon or suspensory ligament explants in vitro,
PRP increases expression of genes of various extracellular matrix
components, increases the ratio of type I collagen to type III collagen, and
decreases expression of genes of various enzymes that catabolize
extracellular matrix components.
PRP can be prepared by either centrifugation or filtration. Centrifugation
systems tend to concentrate platelets less efficiently compared to filtration but
are more efficient at eliminating white blood cells. Concern has been raised
about the presence of high levels of white blood cells in some PRP
preparations because of the possibility that these cells might induce further
inflammation through the release of inflammatory cytokines, a particular
concern with the use of PRP in joints. It is not clear whether this concern has
any relevance to the clinical use but freeze-thawing can be used to remove
leukocytes easily from the PRP although this process may also promote
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February
2016
East
London
Convention
Centre,
East
London,
South
Africa
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