Influence of cryopreservation and mechanical stimulation on equine Autologous Conditioned Plasma (ACP®).

This research examines how freezing and mechanical stimulation affect platelet concentration, growth factor levels, and platelet activation in horse blood plasma. The study found that freezing at -80 C reduces platelet concentration while mechanical stimulation did not enhance growth factor release in the plasma.

Experiment Design and Methods

• Initially, blood was collected from five horses to prepare Autologous Conditioned Plasma (ACP®). Following this, the concentration of platelets, growth factors (specifically, platelet derived growth factor BB and transforming growth factor β1), as well as mean platelet volume and mean platelet component were determined in both fresh and frozen ACP® samples. Samples were cryopreserved for 2 months at two different temperatures: -20 °C and -80 °C.
• In the second part of the research, ACP® was prepared from blood of another nine horses. Half of this ACP® was activated using a freeze-thaw-cycle at -20 °C, whereas the other half was vortexed. The concentrations of the two growth factors were then measured in these samples.

Results and Conclusions

• Results showed a significant decrease in the platelet concentration in the samples cryopreserved at -80 °C. However, the level of platelet derived growth factor BB significantly increased after cryopreservation at both -20 °C and -80 °C. In contrast, the concentration level of the transforming growth factor β1 did not change significantly after cryopreservation.
• The mean platelet volume showed a significant increase after cryopreservation at -20 °C, while both cryopreservation methods resulted in a significant decrease in the mean platelet component.
• The experiment also showed that there were no significant differences in the concentrations of growth factors in the samples that were vortexed compared to those that were not.
• The researchers concluded that while cryopreservation at both temperatures appeared to activate the platelets, storing at -80 °C seemed to damage the platelets without resulting in a higher release of growth factors than storing at -20 °C.
• The additional physical process of vortexing the ACP® did not result in enhanced release of growth factors from the platelets.
• The researchers suggest that cryopreservation of ACP® at -20 °C could be useful in horse veterinary practice, but note that more research is required before this can be recommended. They also suggest adjusting the technique of mechanical stimulation to enhance platelet activation.