**8. Antifibrotic agents**

Many reports indicate that the overproduction of transforming growth factor (TGF)–β in response to injury and disease is a major cause of tissue fibrosis both in animals and humans. It has been shown that anti-fibrotic agents (suramin which acts as a TGF-β1 inhibitor by competitively binding to the growth factor's receptor) inhibits fibroblast proliferation and neutralizes the stimulating effect of TGF-β1 on the proliferation of fibroblasts in vitro (ref). An in-vivo injection of suramin (5.0 mg) two weeks after strain injury reduced muscle fibrosis and enhanced muscle regeneration, thereby leading to improved muscle strength recovery (ref). The clinical use of suramin has already been approved by the Food and Drug Administration. Although suramin can lead to side effects when administered intravenously, local intramus‐ cular injection may not elicit the same deleterious effects and could be very useful in improving muscle healing. However, further studies are necessary in order to assess the safety and the effectiveness of this treatment [32].

popular media as a result of its purported ''natural'' properties, high level of efficacy, and lack

Medical Treatment of Muscle Lesion http://dx.doi.org/10.5772/56329 163

Limited risk of infection is linked to any injective technique but risk may be limited by the use of a correct sterile procedure, Moreover, the utilization of autologus blood guarantees the elimination of the risk of allergic reactions and the possibility to become in contact with infected blood. Previously, bovine derived drugs sometimes led to potentially lethal pathologies of

It seems that PRP does not have a systemic effect, but there is minimal research demonstrating this fact.. Nowadays, there is no evidence that PRP has a carcinogenetic effect. This is also supported by the mechanism of action as growth factors do not penetrate the cellular mem‐ brane; therefore they cannot generate DNA mutations. Actually, no other carcinogenetic

The risk of local complications linked to the use of the PRP technique seems to be more disputed. However, local tissue degeneration, muscular architecture alteration, increasing recurrence rate are all complications which have been taken into consideration in both basic

Different considerations regarding the risk of fibrosis are also of concern. TGF-β1 is the main regulating factor of fibrosis. Thus, it can be speculated that an incorrect use of growth factors may lead to an increase of fibrosis and a potential negative outcome in term of return to play. From an anti-doping perspective, the topical use of growth factors has been approved. This was probably due to the demonstrable absence of any systemic effect of growth factors.

However, despite its elevated public profile and theoretical benefits, there remains many unanswered questions surrounding the use of these techniques in the management of muscle injuries, and the burden of proof remains with scientists and practitioners to confirm or refute

One of the main issues seems to be determining the appropriate PRP concentration to use. Different products are present on the Orthopedics and Sport Medicine market.. However, each product presents different protocols and methods to concentrate the platelets resulting in products with different biological properties. Even if most of the products yield 10% (that means 2ml of PRP for every 20ml of blood withdrawn), their concentration of growth factors is different. It has been estimated that the growth factor concentration may vary from 3 to 27 times blood concentration. Considering that a low concentration of PRP may not give satis‐ factory clinical results and an excessively elevated concentration may start inhibitory proc‐ esses, it appears fundamental that the concentration should be carefully monitored and controlled. Some authors indicate that the ideal concentration of PRP is four to six times the

Another source of discussion is related to the presence (or absence) of White Blood Cells (WBC) in PRP. It is unclear whether the presence of white cells in PRP is an advantage or an obstacle to healing. In fact, if the anti-infective potentialities of WBC may be of benefit, their proin‐ flammatory nature may actually be counterproductive to healing. This premise is consistent

mechanisms are known, so in general, PRP technique seems to be safe in this respect.

coagulation and they have since been withdrawn from the market.

and clinical research. Currently, no studies support such complications.

the clinical utility of this technology.

normal platelet blood concentration.

of side effects.
