Fishman Comment: I have been very impressed with the use of serum tears in the treatment of neuropathic corneal pain. At FishmanVision, we use a subset of serum tears called Plasma Rich in Growth Factors (PRGF). PRGF is itself a subset of PRP. Compared to other modalities, patients appear to find a relief in pain from PRGF. In this paper, the authors suggest that the Endocannabinoid system may be involved. As a quick refresher, The endocannabinoid system is a complex biological regulatory system, conserved among vertebrates, which regulates both systemic and CNS functions that include immune response, pain, neuronal activity, in addition to metabolic and cardiovascular functions
“Platelet-rich Plasma Exerts Antinociceptive Activity by a Peripheral Endocannabinoid-Related Mechanism.” Tissue Eng Part A. 2013 Oct;19(19-20):2120-9.
Authors: Fiorella Descalzi 1, Valentina Ulivi, Ranieri Cancedda, Fabiana Piscitelli, Livio Luongo, Francesca Guida, Luisa Gatta, Sabatino Maione, Vincenzo Di Marzo
In regenerative medicine, platelet by-products containing factors physiologically involved in wound healing, have been successfully used in the form of platelet-rich plasma (PRP) for the topical therapy of various clinical conditions since it produces an improvement in tissue repair as well as analgesic effects. Measurement of endocannabinoids and related compounds in PRP revealed the presence of a significant amount of anandamide, 2-arachidonoylglycerol, palmitoylethanolamide, and oleoylethanolamide. Investigation of the activity of PRP on the keratinocyte cell line NCTC2544 in physiological and inflammatory conditions showed that, under inflammatory conditions, PRP induced in a statistically significant manner the production of these compounds by the cells suggesting that PRP might induce the production of these analgesic mediators particularly in the physiologically inflamed wounded tissue. Studies in a mouse model of acute inflammatory pain induced by formalin injection demonstrated a potent antinociceptive effect against both early and late nocifensive responses. This effect was observed following intrapaw injection of (1) total PRP; (2) lipids extracted from PRP; and (3) an endocannabinoid-enriched lipid fraction of PRP. In all conditions, antagonists of endocannabinoid CB1 and CB2 receptors, injected in the paw, abrogated the antinociceptive effects strongly suggesting for this preparation a peripheral mechanism of action. In conclusion, we showed that PRP and PRP lipid extract exert a potent antinociceptive activity linked, at least in part, to their endocannabinoids and related compound content, and to their capability of elevating the levels of these lipid mediators in cells.