Effects of platelet-rich plasma on recovery process following hindlimb unloading-induced atrophy of gastrocnemius muscle in mice

Platelet-rich plasma (PRP) is plasma with a high platelet concentration, prepared from whole blood. PRP can suppress disuse muscle atrophy, enhance muscle function, and promote muscle recovery. This study aimed to evaluate the effects of PRP on the recovery process following hindlimb unloading (HU)-induced muscle atrophy in mice. Fourteen-week-old male C57BL/6J mice (n = 18) underwent HU for two weeks. The mice were then randomly divided into three groups: HU (n = 5), saline (SA, n = 7), and PRP (n = 6). In the HU group, the gastrocnemius muscles were excised immediately after HU. In the SA and PRP groups, the gastrocnemius muscles were excised after a one-week recovery period following HU. Additionally, in the cage control (CON) group (n = 9), the gastrocnemius muscles were excised without HU procedure. After two weeks of HU, saline or PRP was injected into the gastrocnemius muscle of the right leg (treated side) in the SA or PRP groups, respectively, whereas a sham injection was administered into the left leg (sham side). Only the PRP group showed significantly higher muscle weights and larger cross-sectional areas of type IIA and IIX muscle fibers on the treated side than on the sham side after recovery. These findings suggest that a single injection of PRP can enhance the recovery of fast-twitch muscle fibers following HU-induced disuse atrophy.