The effect of short-term cryopreservation on the properties and functionality of platelet-rich plasma.

Platelet Rich Plasma (PRP) is a biological treatment which, thanks to its enhanced growth factors content, is widely used in the field of regenerative medicine for its reparative effects. Although it is usually used fresh immediately after preparation, its freezing for preservation for future usage could be key in increasing its versatility and new applications. To assess the suitability of freezing, after collecting PRP and platelet lysates (PL) from 6 patients, they were preserved for 1 or 3 months at temperatures of -20ºC and -80°C. Measurements were then made on platelet number and integrity, growth factor levels, biomechanical properties of the clot and its bioactivity on cultured cells. Fresh PRP and PL were used as controls. The results showed an increase in platelet size (p < .01) and clot elasticity (p < .01), as well as decrease in levels of PDGF (P < .05) and VEGF (p < .05), though the overall bioactivity was not affected as culture cells showed the same responsiveness to both frozen and fresh PRP and PL in terms of cell viability. Based on these results, it could be assumed that preservation of PRP by freezing is a feasible and suitable option for its further use.

What is the context? Platelet-Rich Plasma (PRP) is a biological treatment widely used in regenerative medicine as a result of its high content of growth factors.In its routine use, PRP has autologous character, since it is obtained from the same patient and its infiltration in the affected area takes place immediately after it is obtained.Its storability would give PRP versatility in use, which could enable a potential allogeneic use and even significantly reduce the number of blood draws for each patient.It is necessary to establish a PRP storage protocol where its properties are not affected.What is new? PRP was stored at two time points (1 and 3 months) and temperatures (−20ºC and −80ºC) in activated and unactivated states. Afterwards, platelet number, size and activation were measured. Furthermore, the biomechanical properties of the resulting clot, the growth factor content and PRP's impact on cell viability were analyzed.The limiting factor was not having used aggregometry or other techniques that measure other cellular processes, as well as the limited sample size.The results showed that freezing affected platelet size, the levels of platelet-derived GFs and the biomechanical properties of the clot. However, plasmatic levels of growth factors or its capacity to boost cellular proliferation were not affected.What is the impact?The clinical impact of this work is the ability to preserve PRP by freezing. This is especially relevant as it allows a possible use of PRP as an allogeneic treatment. Moreover, its preservation significantly reduces the number of blood draws for each patient, especially in those with puncture difficulties or with apprehension.

Action of Platelet-Rich Plasma on In Vitro Cellular Bioactivity: More than Platelets.

Platelet-rich plasma (PRP) is a biological therapy in which one of the mechanisms of action is the stimulation of biological processes such as cell proliferation. The size of PRP's effect depends on multiple factors, one of the most important being the composition of PRP. The aim of this study was to analyze the relationship between cell proliferation and the levels of certain growth factors (IGF-1, HGF, PDGF, TGF-ß and VEG) in PRP. First, the composition and effect on cell proliferation of PRP versus platelet-poor plasma (PPP) were compared. Subsequently, the correlation between each growth factor of PRP and cell proliferation was evaluated. Cell proliferation was higher in cells incubated with lysates derived from PRP compared to those cultured with lysates derived from PPP. In terms of composition, the levels of PDGF, TGF-ß, and VEGF were significantly higher in PRP. When analyzing the PRP growth factors, IGF-1 was the only factor that correlated significantly with cell proliferation. Of those analyzed, the level of IGF-1 was the only one that did not correlate with platelet levels. The magnitude of PRP's effect depends not only on platelet count but also on other platelet-independent molecules.