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Available from: Amy S Wasterlain, Mar 16, 2014
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    ABSTRACT: Growth hormone (GH) is widely used as a performance-enhancing drug. One of its best-characterized effects is increasing levels of circulating insulin-like growth factor I (IGF-I), which is primarily of hepatic origin. It also induces synthesis of IGF-I in most non-hepatic tissues. The effects of GH in promoting postnatal body growth are IGF-I dependent, but IGF-I-independent functions are beginning to be elucidated. Although benefits of GH administration have been reported for those who suffer from GH deficiency, there is currently very little evidence to support an anabolic role for supraphysiological levels of systemic GH or IGF-I in skeletal muscle of healthy individuals. There may be other performance-enhancing effects of GH. In contrast, the hypertrophic effects of muscle-specific IGF-I infusion are well documented in animal models and muscle cell culture systems. Studies examining the molecular responses to hypertrophic stimuli in animals and humans frequently cite upregulation of IGF-I messenger RNA or immunoreactivity. The circulatory/systemic (endocrine) and local (autocrine/paracrine) effects of GH and IGF-I may have distinct effects on muscle mass regulation.
    British Journal of Pharmacology 07/2008; 154(3):557-68. DOI:10.1038/bjp.2008.153 · 4.99 Impact Factor
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    ABSTRACT: BACKGROUND:Platelet-rich plasma (PRP) is an autologous blood product used to treat acute and chronic tendon, ligament, and muscle injuries in over 86,000 athletes in the United States annually. The World Anti-Doping Agency (WADA) banned intramuscular PRP injections in competitive athletes in 2010 because of concerns that it may increase performance-enhancing growth factors. The ban on PRP was removed in 2011 because of limited evidence for a systemic ergogenic effect of PRP, but the growth factors within PRP remain prohibited. PURPOSE:To quantify the effect of PRP injection on systemic growth factors with performance-enhancing effects and to identify molecular markers to detect treated athletes. STUDY DESIGN:Descriptive laboratory study. METHODS:Six ergogenic growth factors monitored by WADA-human growth hormone (hGH), insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), basic fibroblast growth factor (bFGF or FGF-2), vascular endothelial growth factor (VEGF), and platelet-derived growth factor-BB (PDGF-BB)-were measured in 25 patients before (baseline) and at 0.25, 3, 24, 48, 72, and 96 hours after intratendinous leukocyte-rich PRP injection. Eating and exercise were prohibited for 3 hours before testing. Growth factors were quantified by enzyme-linked immunosorbent assay, and the change relative to each patient's baseline was calculated. RESULTS:Relative to serum, PRP contained significantly more bFGF (226 vs 5 pg/mL), VEGF (1426 vs 236 pg/mL), and PDGF-BB (26,285 vs 392 pg/mL), but IGF-1 and hGH were not elevated. Serum levels increased significantly for IGF-1 at 24 and 48 hours, for bFGF at 72 and 96 hours, and for VEGF at 3, 24, 48, 72, and 96 hours after PRP injection. Additionally, VEGF was increased in all 25 patients after PRP treatment. CONCLUSION:Serum IGF-1, VEGF, and bFGF levels are significantly elevated after PRP injection, supporting a possible ergogenic effect of PRP. An indirect marker for hGH doping, the product of IGFBP-3 × IGF-1, also significantly increased after PRP. Platelet-rich plasma appears to trigger an increase in circulating growth factors through activating biological pathways rather than by serving as a vehicle for the direct delivery of presynthesized growth factors. Elevated VEGF was observed in all patients after PRP, and ≥88% of patients had elevated VEGF at each time point from 3 to 96 hours after PRP, suggesting that VEGF may be a sensitive molecular marker to detect athletes recently treated with PRP. CLINICAL RELEVANCE:This is the first and only adequately powered study of the systemic effects of PRP. We present evidence that PRP contains and may trigger systemic increases in substances currently banned in competitive athletes. Finally, we provide evidence that VEGF could serve as a useful molecular marker to detect athletes treated with PRP.
    The American Journal of Sports Medicine 12/2012; 41(1). DOI:10.1177/0363546512466383 · 4.70 Impact Factor
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    ABSTRACT: Platelet-rich plasma (PRP) has been employed to treat sports injuries to possibly accelerate healing and regeneration. This method offers some potential, especially for athletes. Growth factors are generally prohibited by the World Anti Doping Agency with exception to PRP which may induce adverse effects. The aim of this study was to evaluate any systemic increase of growth factors such as Insulin Like Growth Factor-1, Endothelial Growth Factors, Platelet-Derived Growth Factors, Fibroblast Growth Factors, Vascular-Endothelial Growth Factor and Transforming Growth Factors after local intramuscular administration of PRP in young, healthy male subjects keeping in mind adverse treatment effects. Enriched plasma from centrifuged blood samples was injected into the gluteus muscle. Venous blood was collected and serum prepared before as well as 0.5, 3 and 24 hours after PRP administration. Growth factors were analyzed using ELISA test kits. No significant systemic increase of growth factor levels was found after PRP injection except TGF-β2. For that reason the PRP method may be applied for muscle injury treatment in elite athletes although further studies are necessary to clarify the response to the unspecific increased TGF-β2 blood levels, which could increase the risk for local fibrosis. Key pointsMuscle injuryAutologous conditioned plasmaSystemic circulating growth factorsDoping.
    Journal of sports science & medicine 09/2012; 11(3):551-6. · 0.90 Impact Factor