Efficacy of platelets in bone healing: A systematic review on animal studies.

In presence of large bone defects, delayed bone union, non-union, fractures, and implant surgery, bone reconstruction may be necessary. Different strategies have been employed to enhance bone healing among which the use of autologous platelet concentrates. Due to the high content of platelets and platelet-derived bioactive molecules (e.g., growth factors, antimicrobial peptides), they are promising candidates to increase bone healing. However, a high heterogeneity of both preclinical and clinical studies resulted in contrasting results. Aim of the present systematic review was to evaluate the efficacy of platelet concentrates in animal models of bone regeneration, considering the possible factors which might affect the outcome. An electronic search was performed on MEDLINE and SCOPUS databases. Animal studies with a minimum follow up of 2 weeks and a sample size of five subjects per group, using platelet concentrates for bone regeneration, were included. Articles underwent risk of bias assessment and further quality evaluation was done. Sixty studies performed on six animal species (rat, rabbit, dog, sheep, goat, and mini-pig) were included. The present part of the review considers only studies performed on rats and rabbits (35 articles). The majority of the studies were considered at medium risk of bias. Animal species, healthy models, platelet, growth factors and leukocytes concentration, and type of bone defect seemed to influence the efficacy of platelet concentrates in bone healing. However, final conclusions were not be drawn, since only few included studies evaluated leukocyte, growth factor content, or presence of other bioactive molecules in platelet concentrates. Further studies with a standardized protocol including characterization of the final products will provide useful information for clinical application of platelet concentrates in bone surgery.