Comparative Analyses of Inflammatory Response and Tissue Integration of 14 Hyaluronic Acid-Based Fillers in Mini Pigs

The Assessment, Strategy, and Treatment Protocol: Nasolabial Fold Assessment, Strategy, and Treatment With Hyaluronic Acid Fillers in Chinese Patients

Background

Causes contributing to nasolabial fold (NLF) appearance can be multifactorial, hence requiring distinct dermal filler strategies. We devised 4 assessment, strategy, and treatment (AST) injection protocols, incorporating NLF etiology and severity, patient expectations, and the selection of Belotero Balance Lidocaine (BBL) and Belotero Volume Lidocaine (BVL) hyaluronic acid fillers.

Methods

The underlying etiology and photonumeric assessments of NLF severity guided protocol selection. In protocol 1, the NLF was injected directly with BBL into the mid-to-deep dermis and/or immediate subdermal plane. In protocol 2, BVL was injected using dual-plane sandwich technique into the canine fossa and subcutaneous layers. Protocol 3 combined indirect injections of BVL into the deep medial cheek fat compartment and preauricular hollows to lift ptotic soft tissue, followed by direct NLF injections with protocols 1 and 2. In protocol 4, BVL was injected into the temple and/or jawline, in combination with midface augmentation (AST protocol 3) and direct NLF injections (AST protocols 1 and 2) to fully address all underlying etiologies contributing to NLF appearance.

Results

AST protocols facilitate treatment customization to each patient's NLF etiology and severity through direct and indirect approaches. At 30 days, NLF severity improved visibly and satisfactorily. Improvements varied from effacement of superficial nasolabial wrinkles to shallower NLF depth, improvement in cheek projection and nasojugal groove appearance, and smoother submalar contours.

Conclusions

The AST protocols provide a strategic reference for combining BBL and BVL in a personalized patient-centric approach for effective, holistic, and balanced NLF corrections and pan-facial aesthetic improvements.

Statistical optimization of hyaluronidase production by Ochrobactrum intermedium MEFS strain along with in vivo application in the treatment of aesthetic filler complications

This study aims to optimize the production of microbial hyaluronidase (hyase) from Ochrobactrum intermedium MEFS strain using a statistical model and assess its effectiveness in degrading dermal filler in hairless mice. Plackett-Burman design identified nicotinic acid and CaBr as the main factors affecting hyase activity, with optimal concentrations of 5.51 μg/mL for nicotinic acid and 99.76 mM for CaBr, resulting in hyase activity of 320 U/mL, as determined by a central compound design. The purified hyase was applied to hairless mice to reverse dermal filler complications. Complete degradation occurred after 48 h with 60 U/mL and 72 h with 30 U/mL treatments. Histological analysis showed a strong inflammatory response (neutrophiles accumulation) 24 h post-injection, which shifted to moderate inflammation (mononuclear cells) after 14 days. Hyase treatment reduced inflammation in a dose-dependent manner, with 30 U/mL resulting in mild inflammation and 60 U/mL promoting tissue repair. Histological analysis also revealed that the HA filler was completely eliminated when hyase was used at a dosage of 60 U/mL. This approach has proven more effective in completely eliminating the filler and supporting tissue regeneration. This is the first report of using microbial hyase in filler injections, offering potential for treating aesthetic filler complications.

Comparative analysis of in vivo bio-integration of three hyaluronic acid-based fillers for 26 weeks: a histological study

Stabilized hyaluronic acid (HA), produced through diverse cross-linking technology and formulated as an injectable gel, has found widespread utilization in aesthetic industry. Cross-linked HA essentially constitutes a gel particle composition formed by numerous viscoelastic particulates. Various product formulations yield HA gels with distinct properties, including particle size, viscoelasticity, and interaction forces between particles. While previous studies have primarily concentrated on the biological safety and macroscopic expression of fillers, limited research exists on the internal mechanisms governing their macro-performance. This study selected three common dermal fillers for analysis, establishing an animal model to assess their in vivo interaction with surrounding tissues and explore their internal mechanisms. The findings revealed that particle size plays a crucial role in tissue integration.

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.

Subcutaneous injection of hyaluronic acid leading to emboliom and recanalization process monitored in real time by three-dimensional photoacoustic imaging

This study describes a method for real-time examination of the microvascular system based on the three-dimensional photoacoustic imaging system to prevent arterial complications, especially vascular embolism, during hyaluronic acid (HA) injections. Chicken embryos were used to simulate the superficial blood vessels of human skin, and then the target area was imaged by the photoacoustic imaging system for three-dimensional vascular imaging, and then the syringe and blood vessels were monitored, and the syringe angle and penetration depth were adjusted in time using an injection device to avoid puncturing the arterial vasculature and clogging the blood vessels. HA was then injected into smaller vessels on the dorsum of the tongue in mice and into thicker vessels on the dorsal portion of the tongue in rats to mimic embolization, and the post-operative recovery was reflected by the changes in the pixel dots of the extracted part of the blocked blood vessels, and it was observed that the blood flow in the area of the fine vessels was restored in about 3 days, whereas blood flow in the area of the large vessels was restored in only about 1 h. The method presented in this paper allows precise guidance of injectable filler HA, which has good application prospects in improving the safety of injection micro-plastic surgery and reducing the experience requirements for medical personnel.

Comparison of 2 Fillers for Lip Injection-A Randomized-Controlled Clinical Trial Assessed by 3D Imaging

Background

Lip aging is a concern for many, and hyaluronic acid (HA) injections are a popular solution.

Objectives

This study compared 2 different HA gel technologies (OBT and NASHA) for lip augmentation in 20 volunteers.

Methods

Both groups received treatment from the same injector using the same method. Lip volume was measured with a 3D stereophotogrammetry device before, immediately after, and 30 days posttreatment. Patient satisfaction and adverse events were assessed through FACE-Q scales analysis.

Results

The NASHA group showed an immediate volume increase (P = .01), which decreased after 30 days. The OBT group did not show a significant immediate growth (P = .535) but did exhibit a significant increase after 30 days (P = .014). After 30 days, there were no significant volume differences between the groups (P = .802 and P = .999). FACE-Q analysis revealed no significant differences among groups after 30 days.

Conclusions

This study highlights that less cohesive gels may modify faster in dynamic lip areas, emphasizing the importance of selecting products based on their physicochemical and rheological properties. In the context of lip augmentation with HA, it is important not to consider immediate aesthetic changes as definitive results, as volume changes may persist and develop over time after the treatment.

Level of Evidence 2

Comparative In Vivo Study of Solid-Type Pure Hyaluronic Acid in Thread Form: Safety and Efficacy Compared to Hyaluronic Acid Filler and Polydioxanone Threads

INTRODUCTION

Although various products are commonly used for skin rejuvenation, solid-type hyaluronic acid (HA) as an injectable form has not been researched or utilized. This study aimed to demonstrate the safety and efficacy of solid-type HA in thread form, which differs from the conventional gel-type HA commonly used.

METHOD

Solid-type HA threads, conventional HA fillers, and polydioxanone (PDO) threads were inserted into the dorsal subcutaneous layer of mice. Photographs were taken on days 0, 1, 3, and 7, and on day 7, the samples were harvested for histological analysis. Inflammatory reactions and detection of collagen were confirmed through tissue staining, and real-time PCR was conducted to quantify collagen synthesis.

RESULTS

In the histological analysis, the PDO threads exhibited a greater inflammatory response compared to the HA threads. Masson's trichrome staining revealed a higher degree of collagen synthesis in the HA thread group compared to the HA filler group. While collagen type 1 expression was significantly higher in the PDO thread group than in the HA thread group, the HA thread group showed higher expression levels of collagen type 3. Furthermore, the PDO thread group demonstrated a statistically significant increase in TGF-β1 compared to the HA group.

CONCLUSION

This in vivo study demonstrated the stable application of solid-type pure HA threads and their potential for inducing collagen production, while also yielding a low inflammatory response. The findings highlight the promising applications of solid-type HA in the field of cosmetic dermatology.

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 .

Etiology of Delayed Inflammatory Reaction Induced by Hyaluronic Acid Filler

The etiology and pathophysiology of delayed inflammatory reactions caused by hyaluronic acid fillers have not yet been elucidated. Previous studies have suggested that the etiology can be attributed to the hyaluronic acid filler itself, patient's immunological status, infection, and injection technique. Hyaluronic acid fillers are composed of high-molecular weight hyaluronic acids that are chemically cross-linked using substances such as 1,4-butanediol diglycidyl ether (BDDE). The mechanism by which BDDE cross-links the two hyaluronic acid disaccharides is still unclear and it may exist as a fully reacted cross-linker, pendant cross-linker, deactivated cross-linker, and residual cross-linker. The hyaluronic acid filler also contains impurities such as silicone oil and aluminum during the manufacturing process. Impurities can induce a foreign body reaction when the hyaluronic acid filler is injected into the body. Aseptic hyaluronic acid filler injections should be performed while considering the possibility of biofilm formation or delayed inflammatory reaction. Delayed inflammatory reactions tend to occur when patients experience flu-like illnesses; thus, the patient's immunological status plays an important role in delayed inflammatory reactions. Large-bolus hyaluronic acid filler injections can induce foreign body reactions and carry a relatively high risk of granuloma formation.

Injectable Hyaluronan-Based Thermoresponsive Hydrogels for Dermatological Applications

Most marketed HA-based dermal fillers use chemical cross-linking to improve mechanical properties and extend their lifetime in vivo; however, stiffer products with higher elasticity require an increased extrusion force for injection in clinical practice. To balance longevity and injectability, we propose a thermosensitive dermal filler, injectable as a low viscosity fluid that undergoes gelation in situ upon injection. To this end, HA was conjugated via a linker to poly(N-isopropylacrylamide) (pNIPAM), a thermosensitive polymer using "green chemistry", with water as the solvent. HA-L-pNIPAM hydrogels showed a comparatively low viscosity (G' was 105.1 and 233 for Candidate1 and Belotero Volume^®, respectively) at room temperature and spontaneously formed a stiffer gel with submicron structure at body temperature. Hydrogel formulations exhibited superior resistance against enzymatic and oxidative degradation and could be administered using a comparatively lower injection force (49 N and >100 N for Candidate 1 and Belotero Volume^®, respectively) with a 32G needle. Formulations were biocompatible (viability of L929 mouse fibroblasts was >100% and ~85% for HA-L-pNIPAM hydrogel aqueous extract and their degradation product, respectively), and offered an extended residence time (up to 72 h) at the injection site. This property could potentially be exploited to develop sustained release drug delivery systems for the management of dermatologic and systemic disorders.

Sterile abscess due to hyaluronic acid: A new diagnosis and a proposal for treatment-A series of eight cases

BACKGROUND

In recent years, fillers procedures with hyaluronic acid (HA) have grown significantly. Despite HA relative safety, the number of cases of complications after injections has grown, and in many of which, we are not aware of or have little control over.

AIMS

In this article, the authors describe a new adverse reaction after filling with HA injection, the sterile abscess.

PATIENTS/METHODS

We present eight patients with similar clinical, laboratory, and ultrasound characteristics for sterile abscess and report a new therapeutic modality for it.

RESULTS

All cases were treated with "Munhoz-Cavallieri Lavage Protocol" procedure with complete resolution.

CONCLUSIONS

"Munhoz-Cavallieri Lavage Protocol" serves as a guideline in diagnosis and management of sterile abscess.

Insights on Skin Quality and Clinical Practice Trends in Asia Pacific and a Practical Guide to Good Skin Quality from the Inside Out

OBJECTIVE

We sought to examine the current skin quality trends and gaps in clinical practice in the Asia Pacific region and develop a practical guide to improve skin quality.

METHODS

Medical practitioners from 11 countries in the Asia Pacific region completed an online survey on current trends in skin quality treatment. A panel of 12 leading experts convened for a virtual meeting to develop a practical guide for skin quality improvement.

RESULTS

A total of 153 practitioners completed the survey. The four most common skin quality issues were uneven skin tone, skin surface unevenness, skin laxity, and sebaceous gland hyperactivity and enlarged pores. Most practitioners reported using a combination of treatment modalities for each skin quality issue. It was also observed that each treatment modality could be used to treat several skin quality issues. A multimodal approach targeting different interrelated issues across the tissue planes was recommended for balanced results. The panel developed a practical guide for the appropriate combinations and sequence of treatments, and created treatment protocols for specific skin quality outcome goals. The guide employed an "inside-out" approach, treating the deeper tissue planes prior to the superficial layers to achieve harmonious results.

LIMITATIONS

Future studies are needed to support the recommended treatment protocols for skin quality improvement.

CONCLUSION

These findings provide valuable insights on current skin quality trends and gaps in clinical practice. The practical guide provides a framework for practitioners to customize their treatment plan according to each patient's needs.