INTRODUCTION
The aging process is a complex phenomenon that is influenced by both internal (genetic) and external (environmental) factors. Bone resorption, fat pad repletion, ligament/muscle atrophy, and changes in skin tone, color, and texture all contribute to the loss of a youthful appearance. Injectable soft tissue fillers and neurotoxins are the gold standard in aesthetic medicine for correcting the facial changes associated with aging. These treatments can be used in conjunction with energy-based devices and a daily skincare regimen to achieve natural, long-lasting facial rejuvenation.1
Some fillers, such as hyaluronic acid, volumize the area of injection instantly. Others, such as poly-L-lactic acid (PLLA), are biostimulatory, meaning that they activate resident fibroblasts to produce autologous collagen over time. This leads to a more natural and long-lasting effect.2 The mechanism by which PLLA stimulates neocollagenesis is by triggering a foreign body reaction to the injected material demonstrated by neutrophil and macrophage infiltration from day 2 to day 10 after injection. This is followed by a cellular inflammatory response that leads to the formation of vascularized, connective tissue. PLLA is then hydrolyzed into lactate, converted to pyruvate, and oxidized into carbon dioxide. The inflammatory response subsides in 6 months, but the extracellular matrix production continues, leading to a gradual increase in dermal thickness that can last for at least 2 years.3
PLLA was approved by the US Food and Drug Administration (FDA) in 2004 for the treatment of HIV-associated lipoatrophy, and in 2009 for the correction of shallow to deep nasolabial folds and other facial wrinkles in healthy patients. In 2023, the FDA expanded the approval
Some fillers, such as hyaluronic acid, volumize the area of injection instantly. Others, such as poly-L-lactic acid (PLLA), are biostimulatory, meaning that they activate resident fibroblasts to produce autologous collagen over time. This leads to a more natural and long-lasting effect.2 The mechanism by which PLLA stimulates neocollagenesis is by triggering a foreign body reaction to the injected material demonstrated by neutrophil and macrophage infiltration from day 2 to day 10 after injection. This is followed by a cellular inflammatory response that leads to the formation of vascularized, connective tissue. PLLA is then hydrolyzed into lactate, converted to pyruvate, and oxidized into carbon dioxide. The inflammatory response subsides in 6 months, but the extracellular matrix production continues, leading to a gradual increase in dermal thickness that can last for at least 2 years.3
PLLA was approved by the US Food and Drug Administration (FDA) in 2004 for the treatment of HIV-associated lipoatrophy, and in 2009 for the correction of shallow to deep nasolabial folds and other facial wrinkles in healthy patients. In 2023, the FDA expanded the approval
