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Page 2 of 10 Lin et al. Plast Aesthet Res 2019;6:16 I http://dx.doi.org/10.20517/2347-9264.2019.23

Keywords: Poly-D,L-lactic acid, injectables, fillers, microspheres, biostimulation

INTRODUCTION
Polylactic acid (PLA) was originally synthesized from α-hydroxy acids by French chemists in 1954. This
polymer has been used safely in resorbable suture materials, plates, and screws in orthopedic, neurologic,
[1-6]
and craniofacial surgeries . PLA forms the chiral molecules of poly-L-lactic acid (PLLA), poly-D-lactic
[7]
acid, poly-D,L-lactic acid (PDLLA), and meso-PLA types . Only PLLA and PDLLA have been extensively
studied and have shown promising results [8-10] .
In 1999, injectable PLLA was approved for use in Europe (New-Fill; Biotech Industry SA, Luxembourg,
Luxembourg). PLLA is used to increase the volumes of depressed skin areas, particularly to correct
skin depressions such as creases, wrinkles, folds, scars, and eye rings . PLLA is also useful for treating
[11]
degenerative skin lesions due to aging. In August 2004, injectable PLLA (Sculptra; Dermik Laboratories,
Bridgewater, NJ) was approved for the treatment of HIV-associated facial lipoatrophy in the United
[13]
[12]
States . In 2009, this approval was expanded to include cosmetic applications .
Injectable PDLLA is a new subdermal stimulatory filler (AestheFill; REGEN Biotech, Seoul, South Korea),
and it has identical features as injectable PLLA. Injectable PDLLA is biocompatible, biodegradable,
biostimulatory and long lasting. But the difference is the microparticles of injectable PDLLA are
spongiform microspheres with multiple micropores. The aims of this study were to test the in vivo efficacy
and safety of the injectable PDLLA as a subdermal tissue filler. This biodegradable polymer was injected
into animals from September 1, 2009, to May 1, 2011. The effects and long-term utility of injected PDLLA
microspheres were then investigated in observations of the dorsal parts of 2-week-old Sprague Dawley (SD)
rats.

MATERIALS AND METHODS
Materials
Biodegradable PDLLA filler
The injectable PDLLA used in this study was produced by REGEN Biotech, and comprised 30 to 70 μm
PDLLA microspheres that were white, frozen, and dried solid. The microspheres were suspended in sodium
carboxymethylcellulose as a carrier for injection.

Experimental animals
All animal procedures were conducted in compliance with the relevant laws and regulations of the
Institutional Animal Care and Use Committee of Hallym University. A total of thirty 2-week old male SD
rats were fed sufficient water and food in the animal facility of Hallym University.

Methods
Filler injection
SD rats were anesthetized with ketamine and xylazine and received subdermal injections of 0.5 mL PDLLA
filler into their backs.

Macroscopic observations of the injection sites
On the 2nd, 4th, 8th, 12th, 16th, and 20th weeks after injection, five rats were randomly selected for clinical
observations, and the skin color and volume changes at the injection sites were recorded.