title: Effect of platelet-rich plasma on rat Achilles tendon healing is related to microbiota.
abstract: Background and purpose - In 3 papers in Acta Orthopaedica 10 years ago, we described that platelet-rich plasma (PRP) improves tendon healing in a rat Achilles transection model. Later, we found that microtrauma has similar effects, probably acting via inflammation. This raised the suspicion that the effect ascribed to growth factors within PRP could instead be due to unspecific influences on inflammation. While testing this hypothesis, we noted that the effect seemed to be related to the microbiota. Material and methods - We tried to reproduce our old findings with local injection of PRP 6 h after tendon transection, followed by mechanical testing after 11 days. This failed. After fruitless variations in PRP production protocols, leukocyte concentration, and physical activity, we finally tried rats carrying potentially pathogenic bacteria. In all, 242 rats were used. Results - In 4 consecutive experiments on pathogen-free rats, no effect of PRP on healing was found. In contrast, apparently healthy rats carrying Staphylococcus aureus showed increased strength of the healing tendon after PRP treatment. These rats had lower [corrected] levels of cytotoxic T-cells in their spleens. Interpretation - The failure to reproduce older experiments in clean rats was striking, and the difference in response between these and Staphylococcus-carrying rats suggests that the PRP effect is dependent on the immune status. PRP functions may be more complex than just the release of growth factors. Extrapolation from our previous findings with PRP to the situation in humans therefore becomes even more uncertain.
authors.affiliation: a Department of Clinical and Experimental Medicine, Orthopedics , Linköping University , Linköping , Sweden.|b CAPES Foundation, Ministry of Education of Brazil , Brasília.|c Laboratory of Medical Abilities and Surgical Research , Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) , Porto Alegre , Rio Grande do Sul , Brazil.
authors.forename: Franciele
authors.initials: F
authors.lastname: Dietrich
authors.affiliation: a Department of Clinical and Experimental Medicine, Orthopedics , Linköping University , Linköping , Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Hammerman
authors.affiliation: a Department of Clinical and Experimental Medicine, Orthopedics , Linköping University , Linköping , Sweden.
authors.forename: Parmis
authors.initials: P
authors.lastname: Blomgran
authors.affiliation: a Department of Clinical and Experimental Medicine, Orthopedics , Linköping University , Linköping , Sweden.
authors.forename: Love
authors.initials: L
authors.lastname: Tätting
authors.affiliation: c Laboratory of Medical Abilities and Surgical Research , Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) , Porto Alegre , Rio Grande do Sul , Brazil.
authors.forename: Vinicius Faccin
authors.initials: VF
authors.lastname: Bampi
authors.affiliation: c Laboratory of Medical Abilities and Surgical Research , Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS) , Porto Alegre , Rio Grande do Sul , Brazil.
authors.forename: Jefferson Braga
authors.initials: JB
authors.lastname: Silva
authors.affiliation: a Department of Clinical and Experimental Medicine, Orthopedics , Linköping University , Linköping , Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Aspenberg
mesh_terms: D000125:Achilles Tendon / Q000601:surgery*; D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D007958:Leukocyte Count; D010982:Platelet-Derived Growth Factor / Q000032:analysis; D053657:Platelet-Rich Plasma / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014945:Wound Healing / Q000502:physiology
chemical_list: D010982:Platelet-Derived Growth Factor; C095477:platelet-derived growth factor AB