Back to overviewPLLA: a shift in aesthetic demands
Injectable biostimulators based on poly-L-lactic acid (PLLA) are increasingly being used to stimulate collagen production in the skin. These products must be designed to meet high safety standards, so aesthetic practitioners can feel confident with the injectable and focus on delivering optimal results for their patients. Recently, our dermal bio-activator JULÄINE™ was analyzed in an in vitro laboratory study to determine ease of reconstitution and solubility, as these factors are essential for product performance.1
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From dermal fillers to biostimulator injections
Among the general public, awareness is growing that the body's natural collagen production plays a key role in improving skin quality. This has paved the way for a growing field in aesthetic medicine centered on skin rejuvenation, to address common patient concerns such as skin laxity or sagging skin, skin texture, skin elasticity, or lost volume.
Stimulating collagen production in a low-inflammatory way
While hyaluronic acid based dermal fillers restore volume in target areas, biostimulator injections increase the natural production of collagen in the skin and hence increase skin quality.
JULÄINE™ is a new, scientifically validated PLLA-based injectable that is designed to bio-regenerate. It progressively delivers long-lasting, natural-looking results through collagen regeneration in a low-inflammatory way.2,3
Essential product characteristics of biostimulators
As with any injectable treatment, high standards must be placed on safety. The product needs to be stable and easy to handle, ensuring that administration itself does not lead to errors. Key factors for injectable biostimulators include the size, shape, and surface structure of the particles, as detailed below.
Size range, shape, and surface properties of particles
It has long been established that particle size is of paramount importance in minimizing inflammation in the skin after biostimulator treatments. Either overly small or excessively large particles have the potential to provoke a disproportional inflammatory reaction. Microspheres with diameters of 20-50 μm have been shown to the most suitable size range for treatments.4 Particles should also be below 100 μm to easily pass through a needle.5
Spherical particles have been shown to have the best tissue integration and least activation of inflammatory response.6 Also, particles with a smooth surface texture have a lower tendency to trigger inflammatory responses compared with uneven surfaces.7
Study design
The study evaluated the reconstitution and solubility of JULÄINE™ / LASYNPRO™, following the specifications in the instructions for use. Key focus areas included the ease of dissolution, the uniformity of particle shape and size, and the presence—or absence—of sediments or foam in the reconstituted product.1
Advanced high-resolution camera, digital microscope, and micrometric sieves were used for the analysis. Reconstitution was investigated repeatedly at specified time points over a period of 120 minutes.1
Study results
Reconstitution of the solution: The analysis confirmed that reconstitution occurred rapidly and uniformly. There was no foaming and the mixture did not adhere to the walls of the vial. The resulting solution was homogenous, with a milky-white appearance.1
Sediments and foaming: It took 40 minutes until the first signs of sedimentation of particles were observed. No foam formation was noted.1 This allows sufficient time to prepare and execute the treatment.
Size range and shape of the poly-L-lactic acid microspheres: The microscopic analysis revealed that the particles were generally small, round, and homogenous in shape with sizes ranging from 15-50 μm. The particles did not show any tendency to aggregate during the study period.1 In other words, all particles were close or within the optimal size range.
In summary, JULÄINE™ / LASYNPRO™ exhibited rapid, uniform reconstitution. A homogeneous solution was formed without foam formation and with minimal sedimentation. The particles were small, homogeneous, and spherical.1
Contact us
JULÄINE™ is a biocompatible and biodegradable injectable that activates the body's natural production of collagen.3 It is available in a growing number of markets. Please contact us for more information.
From dermal fillers to biostimulator injections
Among the general public, awareness is growing that the body's natural collagen production plays a key role in improving skin quality. This has paved the way for a growing field in aesthetic medicine centered on skin rejuvenation, to address common patient concerns such as skin laxity or sagging skin, skin texture, skin elasticity, or lost volume.
Stimulating collagen production in a low-inflammatory way
While hyaluronic acid based dermal fillers restore volume in target areas, biostimulator injections increase the natural production of collagen in the skin and hence increase skin quality.
JULÄINE™ is a new, scientifically validated PLLA-based injectable that is designed to bio-regenerate. It progressively delivers long-lasting, natural-looking results through collagen regeneration in a low-inflammatory way.2,3
Essential product characteristics of biostimulators
As with any injectable treatment, high standards must be placed on safety. The product needs to be stable and easy to handle, ensuring that administration itself does not lead to errors. Key factors for injectable biostimulators include the size, shape, and surface structure of the particles, as detailed below.
Size range, shape, and surface properties of particles
It has long been established that particle size is of paramount importance in minimizing inflammation in the skin after biostimulator treatments. Either overly small or excessively large particles have the potential to provoke a disproportional inflammatory reaction. Microspheres with diameters of 20-50 μm have been shown to the most suitable size range for treatments.4 Particles should also be below 100 μm to easily pass through a needle.5
Spherical particles have been shown to have the best tissue integration and least activation of inflammatory response.6 Also, particles with a smooth surface texture have a lower tendency to trigger inflammatory responses compared with uneven surfaces.7
Study design
The study evaluated the reconstitution and solubility of JULÄINE™ / LASYNPRO™, following the specifications in the instructions for use. Key focus areas included the ease of dissolution, the uniformity of particle shape and size, and the presence—or absence—of sediments or foam in the reconstituted product.1
Advanced high-resolution camera, digital microscope, and micrometric sieves were used for the analysis. Reconstitution was investigated repeatedly at specified time points over a period of 120 minutes.1
Study results
Reconstitution of the solution: The analysis confirmed that reconstitution occurred rapidly and uniformly. There was no foaming and the mixture did not adhere to the walls of the vial. The resulting solution was homogenous, with a milky-white appearance.1
Sediments and foaming: It took 40 minutes until the first signs of sedimentation of particles were observed. No foam formation was noted.1 This allows sufficient time to prepare and execute the treatment.
Size range and shape of the poly-L-lactic acid microspheres: The microscopic analysis revealed that the particles were generally small, round, and homogenous in shape with sizes ranging from 15-50 μm. The particles did not show any tendency to aggregate during the study period.1 In other words, all particles were close or within the optimal size range.
In summary, JULÄINE™ / LASYNPRO™ exhibited rapid, uniform reconstitution. A homogeneous solution was formed without foam formation and with minimal sedimentation. The particles were small, homogeneous, and spherical.1
Contact us
JULÄINE™ is a biocompatible and biodegradable injectable that activates the body's natural production of collagen.3 It is available in a growing number of markets. Please contact us for more information.
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References:
1. Comparative Analysis of Reconstitution and Solubility of Two Poly-L-Lactic Acid Fillers for Medical Applications Pawel Kubik , Wojciech Gruszczyński and Monika Filipowska, Polymers (Basel). 2025 Jun 27;17(13):1778.
2. 2024. PLLA medical device implantation study. Local Tissue Effects, Degradation and Performance Following Subcutaneous Injection in Rabbit. NAMSA Intermediate Audited Report. Data on file.
3. 2024. JULÄINE™ Instructions for Use: V4.
4. Guo J. et al., Injectable fillers: current status, physicochemical properties, function mechanism, and perspectives, RSC Adv. , 2023, 13, 23841-23858.
5. Sedush, N.G.; Kalinin, K.T.; Azarkevich, P.N.; Gorskaya, A.A. Physicochemical characteristics and hydrolytic degradation of polylactic acid dermal fillers: A comparative study. Cosmetics 2023, 10, 110.
6. B F Matlaga, L P Yasenchak, T N Salthouse, Tissue response to implanted polymers: the significance of sample shape, J Biomed Mater Res. 1976 May;10(3):391-7.
7. Vaine CA et al., Tuning innate immune activation by surface texturing of polymer microparticles: the role of shape in inflammasome activation, J Immunol. 2013 Apr 1;190(7):3525-32.
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