Repeated PRP Injections Cause Hypersensitivity and Hyperalgesia in Rats

Platelet-Rich Plasma

A recent study in the October issue of the Aesthetic Surgery Journal revealed that multiple injections of both activated and nonactivated platelet-rich plasma (PRP) caused hyperalgesia in rats when compared to saline injections.

Ince Bilsev, MD, et al, shaved 2cm x 2cm areas on the backs of 10 experimental and 10 sham control rats. These areas were divided into four equal squares of 1cm x 1cm and numbered 1 (no treatment; only the needle was inserted), 2 (0.2 mL, saline), 3 (0.2 mL, nonactivated PRP), and 4 (0.2 mL, activated PRP). The researchers used Von Frey filaments to measure the animals’ response to painful stimuli immediately before application and four weeks after the last application. They also took skin biopsies to evaluate growth factors in the injected areas.

All four areas of the backs of the experimental rats developed hyperalgesia. However, areas 3 and 4 (PRP-treated areas) had smaller Von Frey g values than areas 1 and 2. There was no hyperalgesia in the sham group. The biopsies showed higher levels of nerve growth factor (NGF) in areas 3 and 4 than in areas 1 and 2 and the sham group.

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