INTRODUCTION
A new tendency in dermatologic formulations is the use of bioactive proteins for wound healing and cutaneous restoration purposes. These bio-products are aimed at counterbalancing the skin aging exposome defined as “external and internal factors and their interactions, affecting a human individual from conception to death as well as the response of the human body to these factors that lead to biological and clinical signs of skin aging”.1 Skin is a barrier organ that is subjected to a lifelong exposure of a large variety of genetic and environmental factors including sun radiation, pollutants, and nutrition. As skin ages, mechanical, protective, and restorative properties decrease leading to multiple clinical conditions. In recent years growth factors and cytokines have emerged as intriguing therapeutic modalities with burgeoning interest in their potential to serve as actives for cutaneous regeneration.2 In line with these novel approaches, morphogens from human platelet origin are gaining the attention of scientists due to their safe and autologous profile.3Platelet derived autologous products are based on the withdrawal of a small volume of patients’ own blood in order to obtain a platelet rich plasma fraction. The latter has been shown to promote wound healing and tissue regeneration in response to a sustained release of bioactive proteins that act at the site of injury after platelet degranulation.4 The pharmaceutical products that are obtained using plasma rich in growth factors technology (PRGF) provide 100% autologous biological tools including a semi-solid fibrin clot, an injectable formulation, a suturable membrane, a liquid supernatant, eyedrops, and a long-lasting 3D scaffold.5-7 These formulations are in situ prepared and are applied over the affected area. They have proven to be clinically relevant in many medical fields such as dermatology, orthopedic surgery and sports medicine, oral and maxillofacial surgery, neurobiology, and ophthalmology.8-13Cutaneous surface disorders usually represent chronic diseases often establishing their treatment on a long-term basis. As a consequence, it is pivotal that therapies used for the management of these pathologies preserve their functional and biological stability for several weeks in order to be used on a daily dosage. Long-term storage-PRGF formulations such as autologous eye drops have been already tested for their stability. These formulations allow a sustained biologic therapy for ocular disorders such as dry eye without the inconvenience of repeated blood extractions.14 Recently, an autologous topical serum (ATS) based on the patient´s own blood has also been developed overcoming the need of daily regimen dermatological treatments. The latter has proved to contain a high load of key proteins in dermo/epidermal regeneration such as platelet derived growth factor-AB (PDGF-AB), transforming
