Aim: Over the last 15 years, hyaluronic acid (HA) fillers have become the most popular injectable biomaterial for soft tissue correction. With the increasing number of available HA fillers and the multiplication of facial treatments all over the world, there has been a need from physicians to better understand the HA fillers science. There is especially a growing interest in the science-based evaluation of rheological characteristics which represents an essential tool to guide physicians in the selection of the most appropriate HA fillers, administration techniques and depths of injection for their clinical applications. Methods: Four key rheological parameters (viscosity η, elasticity G', normal force F N and elasticity E') are measured and discussed on five HA fillers. Results: These four key rheological parameters are demonstrated to play a pivotal role, in combination with the cohesivity, for better predicting the clinical behavior of HA fillers at different stages of their lifetime. Conclusion: This article discusses the importance of four key rheological parameters during the main steps of the clinical HA fillers' lifetime, from the product injection to the loss of clinical effects. A better knowledge of these HA fillers' rheological parameters can help the physicians to optimize their aesthetic outcomes, safety and patient satisfaction.

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Injectable rejuvenation treatments used in Caucasians might not always suit Asians as the visible signs of aging manifest differently, underscoring a need for Asian-specific strategies that correct underlying structural deficiencies and cumulative age-related changes. The presented Target-Specific Sandwich Technique (TSST) aims to simultaneously restore, rejuvenate, and enhance faces through the distribution of minute amounts of different fillers with different rheologies, using a minimal number of entry points in strategic facial areas and different soft tissue layers in Asians.A total of 14 patients underwent the presented TSST and were subsequently assessed for satisfaction with the treatment and the outcome of the treatment.With 3 cc of fillers, patients experienced a rejuvenated appearance with brow support, brow ridge softening, less severe nasolabial folds, and corrected tear trough hollows. Fillers in the lateral canthal and mandibular angles lifted mouth corners, improved submandibular jowls, and defined the lower face. Although the prejowl sulcus received minimal filler, it appeared subtler, relaxed, and had fewer lines visible while smiling.Overall, patients appeared less tense, rejuvenated, and had improved light reflection and firmer skin. These were due to tissues being supported upward and laterally by fillers in areas of bone resorption-induced volume loss.

Aim: Hyaluronic acid (HA) injectables have gained rapid acceptance for the treatment of skin rejuvenation. A novel HA/sorbitol composition intended for skin quality improvement containing 2.6% of high molecular weight HA stabilized by sorbitol was recently designed to be injected subcutaneously. The aim of this study was to assess the expression of biological markers of skin quality after administration of the composition. Methods: The HA/sorbitol composition was evaluated after injection into the superficial adipose tissue with ex vivo cultured human skin explants versus a product comparator to study the general morphology of the skin tissues and the expression of HA, elastin, collagen type I, collagen type III, and fibrillin-1 in the dermal layer. Results: The results demonstrate that the HA/sorbitol composition is able to boost the production of HA, elastin, collagen type I, collagen type III, and fibrillin-1 in the dermis while providing a proper quality of skin morphology. Conclusion: The HA/sorbitol composition improved biological markers of skin quality in the dermis after product injection into the superficial adipose tissue. This novel composition can be considered as an attractive solution to treat skin aging by injecting a specific HA/sorbitol formulation to strategically target the subcutaneous tissue to improve the quality of the different layers of the skin.

Aim: Skin firmness is one of the key parameters to define skin quality and facial aging. Among the minimally invasive anti-aging strategies, hyaluronic acid (HA) injection is widely accepted to improve skin quality. While most of the available HA injectables are designed and intended for intradermal injection, a novel HA/sorbitol composition containing 2.6% high molecular weight hyaluronic acid stabilized by sorbitol was recently developed to be specifically injected into the adipose tissue to improve the quality of all skin layers, especially the skin firmness. Methods: The HA/sorbitol composition was investigated versus product comparators in terms of biophysical properties, tolerance in subcutaneous tissue with in vivo implantation study, and skin firmness assessment on human skin explants. Results: The HA/sorbitol composition was characterized by unique and differentiated biophysical properties, proper distribution and high tolerance of the gel composition into the adipose tissue, and the ability to efficiently improve skin firmness. Conclusion: The HA/sorbitol composition represents a new attractive solution to treat facial skin aging with an injection strategy specifically targeting the adipose tissue instead of the dermis, to improve the quality of the skin.