Platelet high mobility group box 1 (HMGB1) in platelet-rich plasma (PRP) may play a role in promoting tendon wound healing, according to a mouse model published in PLoS One.

In both the occupational and athletic settings, injuries to the Achilles and patellar tendons are commonplace. These injuries are, furthermore, usually slow to heal and are linked with both a high rate of reinjury and a reduced quality of tendon tissue.

Autologous PRP has been used over the past several decades to help improve the rate of healing, though the efficacy of this method has not been firmly established. As platelets are a rich source of HMGB1, a nuclear protein released by cells when injury occurs, researchers created a mouse model to determine the effects of platelet HMGB1 in PRP on wounded tendon healing.

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The researchers created window defects in the patellar tendons in both platelet HMGB1-knockout (KO) and C57BL/6-Tg (UBC-GFP) mice (GFP mice), and subsequently treated the wounds with saline, PRP from platelet HMGB1-KO mice, or PRP from GFP mice. The animals were killed and analyzed 1 week after treatment.

Analysis suggested that PRP from GFP mice was linked with faster healing and improved tendon structure organization, compared with PRP from platelet HMGB1-KO, which was linked with large premature wound areas and low cell densities in tendon tissue. PRP from GFP mice was also linked with increased extracellular HMGB1, decreased CD68 levels, increased CD146 and CD73 levels, and increased collagen III protein expression levels.

PRP from platelet HMGB1-KO was, however, linked with improved healing when compared with saline treatment.

“These results provide the first evidence for the role of [platelet] HMGB1 within PRP as a therapeutic treatment to promote tendon wound healing,” the authors wrote. “Our findings suggest that the efficacy of PRP treatment for tendon injuries in clinics may depend on [platelet] HMGB1 within PRP preparations.”


Zhang J, Li F, Augi T, et al. Platelet HMGB1 in platelet-rich plasma (PRP) promotes tendon wound healing. PLoS One. 2021;16(9):e0251166. doi:10.1371/journal.pone.0251166