Compared to other domains, tissue engineering and esthetics have dramatically expanded in recent years, leading to both major biomedical advances and futuristic perspectives. The two share a common approach based on biomaterials, especially polymers. This paper illustrates this with the example of polycaprolactone (PCL), a polymer synthesized in the early 1930s, and one of its most recent applications, a PCL-based collagen stimulator, a filler used in esthetics. PCL is biocompatible and biodegradable. Its specific physicochemical and mechanical properties, viscoelasticity and ease of shaping led to the production of PCL-based products with various shapes and durations dependent on its biodegradation kinetics. PCL has been safely used in the biomedical field for more than 70 years, from sutures to tissue and organ replacement by 3D printing. The PCL-based collagen stimulator is composed of PCL microspheres suspended in a carboxymethyl-cellulose gel carrier providing immediate and sustained volumizing effects when injected; the morphology, the biocompatibility of the PCL microspheres embedded with the collagen fibers produced all contribute to the creation of a unique 3D scaffold for a sustained effect. Its safety has been investigated in clinical studies and vigilance surveys. Recently published experts' recommendations on injection modalities and techniques should help further optimize treatment outcome and safety. This paper also integrates reviews and recommendations on the prevention and management of adverse events related to dermal and subdermal fillers including the PCL-based collagen stimulator. In addition, in terms of efficacy and safety, this product benefits from its daily clinical use in esthetics worldwide and continuous extensive fundamental and clinical research, both on it and the PCL polymer. Forthcoming data from further investigations will reinforce knowledge of the product and procedures in the field.

Background: Combinations of minimally invasive procedures (MIPs) are often used in aesthetic treatments and are increasingly considered as the new standard of care. Three agents with specific properties are available in this perspective: a polycaprolactone (PCL)based collagen stimulator, a poly-L-lactic acid (PLLA)-and a poly-glycolic acid (PLGA)based resorbable suspension suture with a 3D-cone technology, and a cross-linked hyaluronic acid (HA). Objective: To develop the first practice guidelines on rejuvenation treatment of the face and the neck using combinations of these agents, whether associated or not with other widely used MIPs such as botulinum neurotoxins or energy-based devices. Methods: A multidisciplinary , multinational board of plastic surgeons and dermatologists convened to develop guidelines using a predefined consensus method. The consensus was defined as ≥83% agreement rate between participants. Results: Practice guidelines and algorithms, describing optimal procedure sequence and spacing, are proposed for the treatment of upper-, mid-, lower-face and neck, combining the PCL collagen stimulator, the PLLA/PLGA suspension sutures, and the cross-linked HA, whether associated or not with other MIPs. Conclusion: These new guidelines provide general support to optimal management strategies. Individual treatment plans should be adapted according to the physician's individual competence and the patient's preferences.

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