Skin chronological aging, also called intrinsic aging, has been characterized on a microscopic level by reductions in total collagen content, elastin synthesis1 and hyaluronic acid content. These reductions are due, in part, to the cells involved becoming senescent and losing their synthesis capabilities.2 Decreases in these skin components further lead to decreased skin thickness, modifications of skin anisotropy, and the loss of skin firmness and elasticity, which are visible at the macroscopic level.
Numerous skin treatments and dermatological procedures, ranging from noninvasive to invasive, are available to promote youthful skin. Such treatments include topical retinoids, glycolic acid, botulinum neurotoxin, soft tissue fillers,3 lasers,4 radio frequency, microneedle stimulation, surgical procedures, endocrine therapies and mesotherapy.5 Over the last decade, interest has increased for minimally invasive techniques, particularly for facial rejuvenation. For example, the injection of fillers6 such as collagen and hyaluronic acid into soft tissue has more frequently been performed.
The ideal dermal filler should offer long-lasting aesthetic improvement with good biocompatibility, and therefore cause minimal side effects. However, all dermal fillers induce transient adverse effects—including pain, discomfort, redness, bruising and swelling—and can sometimes even induce serious and potentially long-lasting adverse effects such as granuloma and infections.7–10 Currently, the major dermal fillers used are based on hyaluronic acid, but since their filling effects are transient, lasting for only six to nine months,3, 11, 12 patients must undergo multiple time-consuming and expensive injection sessions to maintain satisfactory effects.12, 13 On the other hand, collagen-based fillers last no longer in the skin than hyaluronic acid products, and also present drawbacks due to their animal origin—such as the risk of virus and/or bacterial contamination from animals to humans. They also can induce significant allergic reactions due to their protein content.14, 15