Exosomes Isolated From Platelet-Rich Plasma and Mesenchymal Stem Cells Promote Recovery of Function After Muscle Injury

Am J Sports Med. 2020 Jul;48(9):2277-2286. doi: 10.1177/0363546520926462. Epub 2020 Jun 16.


Background: Clinical use of platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) has gained momentum as treatment for muscle injuries. Exosomes, or small cell-derived vesicles, could be helpful if they could deliver the same or better physiological effect without cell transplantation into the muscle.

Hypothesis: Local delivery of exosomes derived from PRP (PRP-exos) or MSCs (MSC-exos) to injured muscles hastens recovery of contractile function.

Study design: Controlled laboratory study.

Methods: In a rat model, platelets were isolated from blood, and MSCs were isolated from bone marrow and expanded in culture; exosomes from both were isolated through ultracentrifugation. The tibialis anterior muscles were injured in vivo using maximal lengthening contractions. Muscles were injected with PRP-exos or MSC-exos (immediately after injury and 5 and 10 days after injury); controls received an equal volume of saline. Histological and biochemical analysis was performed on tissues for all groups.

Results: Injury resulted in a significant loss of maximal isometric torque (66% ± 3%) that gradually recovered over 2 weeks. Both PRP-exos and MSC-exos accelerated recovery, with similar faster recovery of contractile function over the saline-treated group at 5, 10, and 15 days after injury (P < .001). A significant increase in centrally nucleated fibers was seen with both types of exosome groups by day 15 (P < .01). Genes involved in skeletal muscle regeneration were modulated by different exosomes. Muscles treated with PRP-exos had increased expression of Myogenin gene (P < .05), whereas muscles treated with MSC-exos had reduced expression of TGF-β (P < .05) at 10 days after muscle injury.

Conclusion: Exosomes derived from PRP or MSCs can facilitate recovery after a muscle strain injury in a small-animal model likely because of factors that can modulate inflammation, fibrosis, and myogenesis.

Clinical relevance: Given their small size, low immunogenicity, and ease with which they can be obtained, exosomes could represent a novel therapy for many orthopaedic ailments.

Keywords: biological healing enhancement; muscle injury; muscle physiology.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Exosomes / transplantation*
  • Mesenchymal Stem Cells*
  • Muscle, Skeletal / injuries*
  • Platelet-Rich Plasma*
  • Rats
  • Recovery of Function
  • Regeneration