Preparation and properties of polydimethylsiloxane-regulated oriented microporous poly (L-lactic acid) biomimetic bone repair materials.

Despite the exceptional biocompatibility and degradability of Poly (L-lactic acid) (PLLA), its brittleness, low melting strength, and poor bone induction makes it challenging to utilize for bone repair. This study used a simple, efficient solid hot drawing (SHD) method to produce high-strength PLLA, using supercritical CO2 (SC-CO2) foaming technology to give PLLA a bionic microporous structure to enhance its toughness, while precisely controlling micropore homogeneity and improving the melt strength by using Polydimethylsiloxane (PDMS). This PDMS-regulated oriented microporous structure resembled that of natural bone, displaying a maximum tensile strength of 165.9 MPa and a maximum elongation at break of 164.2 %. Furthermore, this bionic structure promoted the polarization of mouse bone marrow macrophages (iBMDM), exhibiting a simultaneous pro- and anti-inflammatory effect. This structure also contributed to the adhesion and growth of mouse embryonic fibroblasts (NIH-3 T3), promoting osteogenic differentiation, which paved the way for developing degradable PLLA bone-repair load-bearing materials.

Safety and effectiveness results of an innovative injectable poly-L-lactic acid-based collagen stimulator (Lanluma®)-Clinical outcomes at 9 months in a post-market study.

BACKGROUND: Injectable fillers for soft tissue augmentation stand out as one of the most favored procedures in the field of aesthetic medicine, especially in addressing the clinical signs of skin aging. Among soft tissue fillers, non-permanent fillers have been safely used in numerous medical applications for several decades. AIMS: The aim of this post-market observational, open-label, uncontrolled, multicentered, prospective study (PMS) was to evaluate the effects of an injectable poly-L-lactic acid-based collagen stimulator (Lanluma®, the study product). PARTICIPANTS/METHODS: This analysis is based on the clinical outcomes data (safety and effectiveness) collected from investigators and participants between the first injection (T0, September 2022) and 9 months thereafter (T3, June 2023) in the treatment of five body-contouring areas. RESULTS: Overall, 70 participants had 99 treatment sessions of the neck (31%), upper arm (20%), hand (17%), thigh (16%) and décolleté (15%). Lumps (neck, upper arm, hand) and nodules (neck, hand, thigh) were the most frequent adverse events (AEs) reported by investigators. All were treatment related. None were serious, severe or fatal. No AEs were reported following treatment of the décolleté. Both investigators and participants reported high levels of satisfaction during the nine-month follow-up period with the treatments in five body areas. CONCLUSIONS: These positive clinical outcomes can be attributed to a proper implementation of best practices and recommendations, and the rheological properties of the study product. This 9-month follow-up analysis should be reconsidered in light of the study's objectives for the final analysis at the 25-month follow-up.

Heterogeneous porous hypoxia-mimicking scaffolds propel urethral reconstruction by promoting angiogenesis and regulating inflammation.

The nasty urine microenvironment (UME) impedes neourethral regeneration by inhibiting angiogenesis and inducing an excessive inflammatory response. Cellular adaptation to hypoxia improves regeneration in numerous tissues. In this study, heterogeneous porous hypoxia-mimicking scaffolds were fabricated for urethral reconstruction via promoting angiogenesis and modulating the inflammatory response based on sustained release of dimethyloxalylglycine (DMOG) to promote HIF-1α stabilization. Such scaffolds exhibit a two-layered structure: a dense layer composed of electrospun poly (l-lactic acid) (PLLA) nanofibrous mats and a loose layer composed of a porous gelatin matrix incorporated with DMOG-loaded mesoporous silica nanoparticles (DMSNs) and coated with poly(glycerol sebacate) (PGS). The modification of PGS could significantly increase rupture elongation, making the composite scaffolds more suitable for urethral tissue regeneration. Additionally, sustained release of DMOG from the scaffold facilitates proliferation, migration, tube formation, and angiogenetic gene expression in human umbilical vein endothelial cells (HUVECs), as well as stimulates M2 macrophage polarization and its regulation of HUVECs migration and smooth muscle cell (SMCs) contractile phenotype. These effects were downstream of the stabilization of HIF-1α in HUVECs and macrophages under hypoxia-mimicking conditions. Furthermore, the scaffold achieved better urethral reconstruction in a rabbit urethral stricture model, including an unobstructed urethra with a larger urethral diameter, increased regeneration of urothelial cells, SMCs, and neovascularization. Our results indicate that heterogeneous porous hypoxia-mimicking scaffolds could promote urethral reconstruction via facilitating angiogenesis and modulating inflammatory response.

Safety of the Immediate Reconstitution of Poly-l-Lactic Acid for Facial and Body Treatment-A Multicenter Retrospective Study.

BACKGROUND: Poly-l-lactic acid (PLLA-SCA; Sculptra) was approved in 1999 in Europe and 2004 in United States as a collagen biostimulator. It is a freeze-dried preparation containing 150 mg PLLA-SCA per vial and, since approval, has been recommended to be reconstituted 72 h before treatment, which can hinder its use in clinical practice. In 2021, the manufacturer authorized the reconstitution of PLLA-SCA immediately before use. OBJECTIVE: To evaluate adverse events in patients treated with immediately reconstituted PLLA-SCA on the face, body, and scars. METHOD: This was a retrospective analysis of medical records of patients treated with immediately reconstituted PLLA-SCA for aesthetic purposes from January 1, 2021, to December 31, 2021, at two medical centers. RESULTS: A total of 274 treatment sessions were conducted on 167 patients (ranging from 1 to 5 sessions per patient). Of these, 228 sessions (151 patients) targeted the face, 39 sessions (22 patients) addressed the body, and 7 sessions (5 patients) focused on scars. The mean final concentration of PLLA-SCA was 15.30 mg/mL for the face, 8.35 mg/mL for the body, and 10.53 mg/mL for scars. The majority of injections were administered with a blunt cannula (face: 87.3%, body: 100%, scars: 57%), and in 6 out of 7 scar treatments, PLLA-SCA was additionally applied topically after fractional treatment. One patient developed a PLLA-SCA nodule 30 days after facial treatment, which resolved after two saline injections. The most common adverse events were bruising (face: 6.57%, body: 7.69%) and mild pain (face: 3.07%). No events required further intervention. CONCLUSION: This study reports an adverse event profile with immediately reconstituted PLLA-SCA, used on the face, body, and scars, similar to that reported with PLLA-SCA reconstituted 72 h prior to use. TRIAL REGISTRATION: This was a retrospective study of medical records at two medical centers, and trial registration was not required.

Poly-d,l-Lactic Acid Via Transdermal Microjet Drug Delivery for Treating Rosacea in Asian Patients.

BACKGROUND: Rosacea, a chronic inflammatory skin condition, is marked by enduring redness, visible blood vessels, and inflammatory eruptions in facial areas. Managing rosacea remains a persistent challenge for dermatologists, especially in cases unresponsive to conventional treatments. Injectable poly-d,l-lactic acid (PDLLA) has shown promise in treating erythema and telangiectasia associated with rosacea in addition to age-related concerns. Employing Mirajet, a laser-induced microjet system, for administering PDLLA is a novel and promising treatment for rosacea. AIMS: We aimed to evaluate the efficacy and safety of injectable PDLLA delivered via a needle-free microjet system for managing rosacea. METHODS: Four Korean women with persistent and refractory rosacea received five monthly sessions of PDLLA needle-free injections. Clinical assessments were conducted using the Clinician's Erythema Assessment and Patient's Self-Assessment (PSA) at baseline, 4 weeks post-treatment, and 22 weeks post-final treatment. Adverse events were monitored throughout the study period. RESULTS: At 4 weeks post-treatment, both Clinician's Erythema Assessment and PSA scores indicated significant improvements in erythema that were sustained up to the 22-week follow-up. Patients reported high satisfaction with resolution of redness and improved skin texture. Mild swelling, redness, and petechiae were observed post-treatment but resolved spontaneously. No product-related adverse events were noted during the study period. CONCLUSION: Injectable PDLLA delivered via laser-induced microjet injection demonstrated promising efficacy in improving rosacea symptoms and skin quality for up to 22 weeks without significant adverse effects. Larger randomized controlled trials are needed to confirm these findings and evaluate long-term safety and sustainability of outcomes.

Efficacy and Safety of Poly-l-Lactic Acid in Facial Aesthetics: A Systematic Review.

The primary objective of this systematic review study was to investigate the effectiveness, durability, and adverse events of PLLA treatment for aesthetic indications. The search strategy was performed in MEDLINE (Ovid). The electronic literature search of five databases was performed, from the inception of the databases until the 12th of February 2024. This was to identify randomized clinical trials that assessed PLLA treatment in adult individuals exhibiting facial aging and/or facial lipoatrophy. Risk of bias was assessed using the Cochrane Risk-of-Bias Tool for Randomized Trials (RoB 2). Eleven RCTs out of 1467 identified citations were included. Four studies showed increased dermal thickness, significant improvement in facial lipoatrophy severity and aesthetic clinical scores, after PLLA treatment with its effects sustained for at least 25 months. Two studies demonstrated the superiority of PLLA over injectable human collagen. Also, three studies showed positive results favoring PLLA when compared with PH gel in lipoatrophy severity, transepidermal water loss, skin quality, elasticity, and patient satisfaction. All adverse events were mild-to-moderate in intensity, and the main ones worth noting were bruising, hematoma, tenderness, nodules, and edema. Five out of eleven studies were considered having high risk of bias. The evidence on the effectiveness and safety of PLLA for facial rejuvenation is of low quality; thus, the reported high effectiveness, safety, and long-lasting effects for this purpose should be further investigated.

Poly-d,l-lactic Acid (PDLLA) Application in Dermatology: A Literature Review.

Poly-d,l-lactic acid (PDLLA) is a biodegradable and biocompatible polymer that has garnered significant attention in dermatology due to its unique properties and versatile applications. This literature review offers a comprehensive analysis of PDLLA's roles in various dermatological conditions and wound-healing applications. PDLLA demonstrates significant benefits in enhancing skin elasticity and firmness, reducing wrinkles, and promoting tissue regeneration and scar remodeling. Its biodegradable properties render it highly suitable for soft tissue augmentation, including facial and breast reconstruction. We discuss the critical importance of understanding PDLLA's physical and chemical characteristics to optimize its performance and safety, with a focus on how nano- and micro-particulate systems can improve delivery and stability. While potential complications, such as granuloma formation and non-inflammatory nodules, are highlighted, effective monitoring and early intervention strategies are essential. PDLLA's applications extend beyond dermatology into orthopedics and drug delivery, owing to its superior mechanical stability and biocompatibility. This review underscores the need for ongoing research to fully elucidate the mechanisms of PDLLA and to maximize its therapeutic potential across diverse medical fields.

Urchin-like NiCo-based bimetallic hydroxide decorated with DOPO as highly hydrophobic flame retardant for remarkably reducing fire hazard of poly (L-lactic acid).

Designing high-performance flame retardants for poly (L-lactic acid) (PLA) materials and exploring a simple and scalable strategy have been hot topics in research. In this work, a novel and highly efficient flame retardant, that is, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) decorated urchin-like NiCo-based bimetallic hydroxide (NiCo-BH@DOPO), was synthesized and incorporated into PLA to prepare PLA and NiCo-BH@DOPO (PLA/NiCo-BH@DOPO) composite. Benefiting from the DOPO organic modification, NiCo-BH@DOPO had superb hydrophobicity and presented excellent dispersion in the PLA matrix. When 20 wt% NiCo-BH@DOPO was added, the LOI value of PLA/NiCo-BH@DOPO composites reached 33.2 %, passed the V-0 level of UL-94 grade, and its maximum peak heat release rate (PHRR) and total heat release (THR) were reduced by 13.2 % and 17.3 %, respectively, compared with PLA/NiCo-BH composites. Furthermore, the residue of PLA/NiCo-BH@DOPO at 800 °C reached 19.8 wt% and the T10% (temperature at 10 % weight loss) increased by 33 °C. More importantly, the residual PLA/NiCo-BH@DOPO char exhibits a significantly reduced presence of large cracks compared to PLA/NiCo-BH, indicating a more compact formation of residual char. NiCo-BH@DOPO endowed PLA with outstanding flame retardancy, thermal stability and carbonization properties, which were owing to the multi-coordinating effect transition metal (NiCo-BH) catalyzed the char formation to form a char layer barrier and DOPO free radicals captured to inhibit the combustion reaction chain. This investigation provided a facile strategy for the novel multi-function NiCo-based bimetallic hydroxide flame retardant, expanding NiCo-BH potential applications in PLA.

Combined Forehead and Temporal Lifting: An Innovative Approach to Lanluma V Treatment.

BACKGROUND: Excess skin laxity over the upper face can contribute to aging over the mid and lower face. We describe an innovative nonsurgical technique of facial rejuvenation by injecting Lanluma V over the scalp's vertex and parietal regions. Lanluma V is a poly-l-lactic acid (PLLA)-based collagen stimulator which contains 210 mg of PLLA, distributed by Sinclair Pharmaceutical. Lanluma V works by stimulating collagen regeneration to provide support for the treated area. METHOD: A retrospective review of 12 consecutive patients treated with Lanluma V over the vertex and parietal regions of the scalp to achieve nonsurgical rejuvenation of the upper, middle, and lower thirds of the face was conducted. The patients were treated over two sessions, 1 month apart. The treated patients were reviewed by a plastic surgeon and rated under the Global Aesthetic Improvement Scale (GAIS) 6 months after treatment. RESULTS: The patients achieved an overall average of 1.16 grade improvement in GAIS. The average follow-up period is 6 months following completion of treatment. There was no reported incidence of non-scarring alopecia, which has been reported in the use of other, more viscous fillers such as calcium hydroxyapatite or high G' hyaluronic acid. CONCLUSION: This innovative method of combined forehead and temporal lifting with Lanluma V allows for an average 1.16 grade improvement in GAIS. There is no reported incidence of non-scarring alopecia, which has been associated with other fillers.

Biodegradable polymers and platelet-rich plasma causing visual impairment: a literature review.

BACKGROUND: Dermal fillers are widely used for facial rejuvenation and esthetic enhancement, offering temporary solutions for aging and volume loss. Despite their general safety, a rare but severe complication associated with these fillers is visual impairment, including blindness. This underscores the need for a thorough understanding of risks associated with various filler materials. Historical cases of blindness following filler injections date back to 1963, with increasing reports linked to the expansion of the cosmetic filler industry. While hyaluronic acid (HA) and autologous fat have been extensively studied, other fillers such as calcium hydroxylapatite and poly-l-lactic acid (PLLA) are less understood. OBJECTIVE: This systematic review aims to address gaps in the literature by providing a comprehensive overview of visual impairment caused by fillers other than HA and autologous fat. We systematically examine the prevalence, causes, clinical features, and treatment outcomes associated with these less common fillers. MATERIALS AND METHODS: A comprehensive literature search was conducted across databases including PubMed, Scopus, and Google Scholar using terms related to visual impairment and dermal fillers. Studies published between 2014 and 2021, including observational studies and case reports, were included. Studies were selected based on predefined inclusion and exclusion criteria, and a PRISMA flow diagram was used to illustrate the study selection process. RESULTS: The review identifies and summarizes cases of visual impairment associated with calcium hydroxylapatite, poly-d,l-lactic acid (PDLLA), and PLLA fillers. Key findings reveal that visual impairment following these fillers is rare but can occur suddenly or within a few days of the procedure. Cases of delayed onset up to two weeks are also noted, emphasizing the need for extended post-procedure monitoring. DISCUSSION: The review highlights unique insights into the risks associated with non-HA fillers, such as the heightened risk in the periorbital region and other facial areas. It explores mechanisms of complications, including retrograde flow of emboli leading to retinal ischemia. The discussion also covers emergency protocols and preventative measures, providing valuable guidance for managing and mitigating risks. CONCLUSIONS: Visual impairment caused by fillers other than HA and autologous fat, while rare, represents a serious complication that requires careful attention. This review contributes new perspectives on the differential risks of various fillers, symptom onset variability, and anatomical risk factors. Emphasizing the importance of proper patient selection, technique, and monitoring, it calls for further research to better understand and prevent these complications, ultimately aiming for safer and more effective use of soft-tissue fillers.

Bimetallic Fe/Co-MOF dispersed in a PVA/chitosan multi-matrix hydrogel as a flexible sensor for the detection of lactic acid in sweat samples.

A novel bimetallic Fe/Co-metal-organic framework (MOF) hydrogel-based wearable sweat sensor was developed. Morphological and structural analysis of the hydrogel shows uniformly sized spines and spindle-shaped particles of the Fe/Co-MOF, and it has a high surface area (132.306 m2 g-1) and porosity (0.059 cm3 g-1) as confirmed by Brunauer-Emmett-Teller (BET) studies. The integration of the bimetallic MOF into a polyvinyl alcohol/chitosan (PVA/CS)-mixed matrix resulted in a multiple network hydrogel. The optimisation study investigated  the effects of different pH of the PBS electrolyte, scan rates, and accumulation time in voltammetry. The electrochemical methods such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) provided information on the redox behaviour, electrochemical stability, and catalytic activity of the hydrogel. The sensor demonstrates a wide linear detection range from 0.05 µM to 100 mM, a superior sensitivity of 0.02 mA mM-1 cm-2, and a lower limit of detection of 0.01 µM . Active sites distributed over the hydrogel surface, specifically Fe2+ and Co2+ within the MOF structure, catalyse the oxidation of L-lactic acid, resulting in electron transfer and the formation of pyruvic acid. Notably, the fabricated sensor exhibits high selectivity, effectively discriminating against interfering species such as uric acid, ascorbic acid, glucose, urea, dopamine, NaCl, and CaCl2. Real-time analysis conducted in a simulated sweat sample via the standard addition method resulted in good recovery percentages of a minimum of 98%. The work presented here is a versatile and simple platform for point-of-care testing, especially for athletes and military personnel.

Adaptive evolution of Paecilomyces variotii enhanced the biodetoxification of high-titer inhibitors in pretreated lignocellulosic feedstock.

High inhibitor concentrations in lignocellulose feedstock negatively affect the degradation rate of biodetoxification strains. This study designed two adaptive laboratory evolutions in solid substrate and liquid medium to boost the biodetoxification capacity of P. variotii to high titers of lignocellulose-derived inhibitors, resulting in two evolved strains AC70 and ZW70. The results showed that the evolutionary adaptation in liquid medium could better boost the acetic acid assimilation compared to that on solid substrate. Transcriptional analysis revealed that the evolved strains exhibited a significant upregulation of adh, acs, ach1, and ackA directly related to the initial steps of acetate and furan aldehydes metabolisms. ZW70 strain can effectively remove the high concentration inhibitors cocktail from the hydrolysates derived from pretreated wheat straw and furfural residues. The biodetoxified hydrolysates by ZW70 were successfully used for cellulose chiral L-lactic acid production with the titers of ∼110 g/L, which were over 20 % higher than that detoxified by parental strain.

MXene-coated piezoelectric poly-L-lactic acid membrane accelerates wound healing by biomimicking low-voltage electrical pulses.

Electrical stimulation therapy is effective in promoting wound healing by rescuing the decreased endogenous electrical field, where self-powered and miniaturized devices such as nanogenerators become the emerging trends. While high-voltage and unidirectional electric field may pose thermal effect and damage to the skin, nanogenerators with lower voltages, pulsed or bidirectional currents, and less invasive electrodes are preferred. Herein, we construct a polydopamine (PDA)-modified poly-L-lactic acid (PLLA) /MXene (PDMP/MXene) nanofibrous composite membrane that generates piezoelectric voltages matching the transepithelial potential (TEP) to accelerate wound healing. PDA coating not only enhances the piezoelectricity of PLLA by dipole attraction and alignment, but also increases its hydrophilicity and facilitates subsequent MXene adhesion for electrical conductivity and stability in physiological environment. When applied as wound dressings in mice, the PDMP/MXene membranes act as a nanogenerators with reduced internal resistances and satisfactory piezoelectric performances that resemble bioelectric potentials (~10 mV) responding to physical activities. The membrane significantly accelerates wound closure by facilitating fibroblast migration, collagen deposition and angiogenesis, and suppressing the expression of inflammatory responses. This piezoelectric fibrous membrane therefore provides a convenient solution for speeding up wound healing by sustained low voltage mimicking bioelectricity, better cell affinity.

Poly-L-lactic acid fillers for nasal alar retraction: safety and effectiveness in 13 cases.

OBJECTIVE: To assess the effectiveness and safety of poly-L-lactic acid (PLLA) fillers in treating nasal alar retraction. We conducted a series of case reports on 13 patients treated for nasal alar retraction at the Chengdu Ningyue FRESKIN Medicine Cosmology Clinic from September 2022 to July 2023. Patients ranged from 23 to 49 years, comprising 12 females and 1 male. Of these, 5 had no prior medical history, 7 had previously undergone rhinoplasty, and 1 had a history of nasal trauma. Treatment outcomes and adverse reactions were monitored following PLLA filler injections. The mean pre-treatment severity score was 1.62±0.65, improving to 0.54±0.66 post-treatment (t=4.19, df=23, P<0.001). All participants reported satisfaction with their results without adverse effects. PLLA facial fillers are a safe and effective treatment for nasal alar retraction, presenting no embolism risk. This treatment merits consideration for broader clinical application.

The AestheCode System: A Safe and Efficient Guide for AestheFill Injection.

AestheFill is a biostimulator based on poly-D,L-lactic acid. It is supplied as lyophilized powders and is referred to as a versatile biostimulator. According to the amount of water added, the suspensions can be vary in thickness which can be divided into four groups for different indications: the thickest suspension (D1.5-3) for nose or chin augmentation, thick suspension (D3-6) for deep wrinkle correction, thin suspension (D6-12) for shallow wrinkle correction, and super-thin suspension (D12-24) for skin rejuvenation. However, practitioners may be confused about which filler thickness, injection layer, method, and amount should be chosen for their patients. Biostimulators tend to form non-inflammatory nodules if technical mishaps occur during injection. Based on 10 years of AestheFill injection experience, the authors proposed the AestheCode system for the safe and effective injection of AestheFill.Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Biodegradable Poly (L-Lactic acid) Fibrous Membrane with Ribbon-Structured Fibers and Ultrafine Nanofibers Enhances Air Filtration Performance.

Here, the poly (l-lactic acid) (PLLA) membrane with multi-structured networks (MSN) is successfully prepared by electrospinning technology for the first time. It is composed of micron-sized ribbon-structured fibers and ultrafine nanofibers with a diameter of tens of nanometers, and they are connected to form the new network structure. Thanks to the special fiber morphology and structure, the interception and electrostatic adsorption ability for against atmospheric particulate matter (PM) are significantly enhanced, and the resistance to airflow is reduced due to the "slip effect" caused by ultrafine nanofibers. The PLLA MSN membrane shows excellent filtration performance with ultra-high filtration efficiency (>99.9% for PM2.5 and >99.5% for PM0.3) and ultra-low pressure drop (≈20 Pa). It has demonstrated filtration performance that even exceeds current non-biodegradable polymer materials, laying the foundation for future applications of biodegradable PLLA in the field of air filtration. In addition, this new structure also provides a new idea for optimizing the performance of other polymer materials.

Accelerated degradation testing impacts the degradation processes in 3D printed amorphous PLLA.

Additive manufacturing and electrospinning are widely used to create degradable biomedical components. This work presents important new data showing that the temperature used in accelerated tests has a significant impact on the degradation process in amorphous 3D printed poly-l-lactic acid (PLLA) fibres. Samples (c. 100 µ m diameter) were degraded in a fluid environment at 37 ° C, 50 ° C and 80 ° C over a period of 6 months. Our findings suggest that across all three fluid temperatures, the fibres underwent bulk homogeneous degradation. A three-stage degradation process was identified by measuring changes in fluid pH, PLLA fibre mass, molecular weight and polydispersity index. At 37 ° C, the fibres remained amorphous but, at elevated temperatures, the PLLA crystallised. A short-term hydration study revealed a reduction in glass transition (Tg), allowing the fibres to crystallise, even at temperatures below the dry Tg. The findings suggest that degradation testing of amorphous PLLA fibres at elevated temperatures changes the degradation pathway which, in turn, affects the sample crystallinity and microstructure. The implication is that, although higher temperatures might be suitable for testing bulk material, predictive testing of the degradation of amorphous PLLA fibres (such as those produced via 3D printing or electrospinning) should be conducted at 37 ° C.

Clinical applications of a novel poly-L-lactic acid microsphere and hyaluronic acid suspension for facial depression filling and rejuvenation.

BACKGROUND: Poly L-lactic acid (PLLA) can stimulate fibrous tissue regeneration to exert a filling effect. However, severe inflammatory reactions and unsatisfactory effects remain a concern. OBJECTIVE: Herein, we describe the mechanism of action, efficacy, and safety of PLLA microspheres in suspension (PLLA-b-PEG/HA) for facial contouring and soft tissue augmentation. METHODS: PLLA-b-PEG/HA, ssynthesized by copolymerization with ethylene glycol, were suspended in hyaluronic acid (HA). Physiological verification was performed using scanning electron microscopy and X-ray computed tomography. PLLA-b-PEG/HA were subcutaneously injected into the dorsal region of 4-month-old rabbits. Ultrasound assessed volumetric capacity at 3 days and 1, 2, 4, and 12 weeks. The inflammatory response, collagen production, and HA degradation were evaluated. A retrospective case series of 10 patients who received PLLA-b-PEG/HA injections was conducted to assess long-term efficacy and safety. RESULTS: PLLA-b-PEG exhibited a spherical structure with a smooth surface (20-45 µm diameter). In rabbits, implant site volume increased within 4 weeks, gradually decreasing thereafter. Fibrous capsules, microvessel density, and new collagen fiber formation progressively increased at 4, 12, and 26 weeks after injection. Clinical data demonstrated significant improvements in face contouring at months 3 and 12 after injection. All patients showed improved internal contours based on the Global Aesthetic Improvement Scale. After 12 months, 90% of the patients retained good shaping and support effects with minimal adverse reactions. CONCLUSIONS: PLLA-b-PEG/HA demonstrated superior biocompatibility and facial regeneration potential, with outstanding dual collagen-stimulating properties. The clinical efficacy and safety of PLLA-b-PEG/HA have been validated and established as a promising therapeutic option.

Poly-L-Lactic Acid Reduces the Volume of Dermal Adipose Tissue Through its Metabolite Lactate.

Poly-L-lactic acid (PLLA), a well-established biostimulator that induces collagenases, is widely used among clinical practice to treat skin aging. However, the precise regulatory effect of PLLA on different dermal cell subsets beyond fibroblast has not been fully elucidated. In this study, we constructed in vivo PLLA injection and in vitro PLLA-adipocyte co-culture models to analyze the regulatory effects of PLLA on the volume, differentiation, lipolysis, and thermogenic capacity of dermal adipocyte. We found that PLLA injection significantly reduced the thickness of dermal fat in mice. In co-culture assay, PLLA showed no effect on adipogenesis, but stimulated the lipolysis activity. Interestingly, PLLA also enhanced the differentiation of fat cells into beige fat cells, which possess higher thermogenic capacity. In mechanical study, we blocked adipocyte lactate uptake with a monocarboxylate transporter (MCT1/4) inhibitor and found that the regulatory effect of PLLA on dermal adipocyte relies on its metabolite lactate. In summary, our results suggest that PLLA has complex regulatory effects on the dermal cells, and its ability to improve skin aging is not fully attributed to stimulating collagen synthesis, but also partially involves adipocytes.No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .