Rheologic and Physicochemical Characteristics of Hyaluronic Acid Fillers: Overview and Relationship to Product Performance

Male Rejuvenation: Injectables

The use of injectables can effectively treat the areas of greatest facial esthetic concern in males. Due to significant differences in the facial anatomy of men compared to women, treatment strategy, dosage, and technique differs. This article will review the pharmacology, preparation, pertinent anatomy, technique, risks, and adverse events associated with injectable agents emphasizing unique differences in male anatomy and esthetics.

Nonsurgical Rhinoplasty: Results from a Retrospective Study of Rino-4-Puntos Technique with Hyaluronic Acid

BACKGROUND

Nonsurgical rhinoplasty (NSR) utilizing hyaluronic acid (HA) filler injections is increasingly used to address nose shape issues. While refinements have been proposed, the technique lacks standardization.

OBJECTIVES

Our study aimed to evaluate the aesthetic outcome, longevity of results, safety, and patient satisfaction with the novel Rino-4-Puntos (R4P) NSR technique.

METHODS

This is a retrospective study of consecutive individuals treated with R4P between January 2021 and July 2023. All participants had one of the four indications: rectification of the dorsum (21%), triangulation of the tip (32%), projection (25%), and strengthening of the columella (22%). Each patient received two hyaluronic acid (HA) fillers: one with intermediate G prime (G') at Points 1-3 and another with high G' at Point 4, which is further divided into Points 4.1, 4.2, 4.3, and 4.4. The injection points were as follows: P1 (radix, 0.05-0.15 mL, supraperiosteal), P2 (supratip, 0.025 mL, suprachondrial), P3 (tip, 0.15 mL, deep fat), P4 (columella, 0.30 mL, supraperiosteal [4.1], or deep fat [4.2, 4.3, and 4.4]).

RESULTS

Four hundred individuals (n = 284 [71%] females) are included. The mean filler volume used was 0.65 ± 0.17 mL. Injecting small boluses (≤ 0.05 mL) in the midline at deep planes minimized the risk of adverse effects, as no vascular complications occurred. Ninety-three percent of participants considered the overall outcome at least satisfactory ("good," "very good," or "excellent"). The treatment effect was maintained for a median of 11 months.

CONCLUSIONS

The R4P technique refines NSR by combining enhanced aesthetic outcome, longevity, and safety.

LEVEL OF EVIDENCE IV

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 .

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.

Jawline Sharp Contouring With Hybrid Filler

BACKGROUND

Having a well-defined jawline is a sign of youth and attractiveness among both men and women. Soft tissue fillers, such as calcium hydroxylapatite (CaHA) and hyaluronic acid (HA) fillers, offer nonsurgical alternatives for rejuvenating the lower face and enhancing the jawline. The aim of this study was to investigate the use of a premixed combination of HA with cohesive polydensified matrix technology (CPM, Belotero Intense, CPM-I) and CaHA to create a sharply defined jawline.

METHODS

A total of 126 patients were enrolled in the study and treated with a premixed combination of CPM-I and CaHA using a retrograde fanning injection technique with cannulas. The injection volumes and product ratios were customized according to the patients' needs.

RESULTS

The cohort consisted of 75 females and 51 males. The average injected volume of premixed CaHA:CPM-I was 5.83 mL. In the majority of patients, a 1:1 syringe ratio of CaHA:CPM-I was applied (n = 81, 64.2%). No adverse events were reported during the 6-month follow-up period.

CONCLUSION

The hybrid filler approach investigated in this study shows promise for achieving well-defined, long-lasting jawline contours.

LEVEL OF EVIDENCE IV

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 .

In Vitro Cytocompatibility Analysis and Comparison of Different Hyaluronic Acid Fillers for Minimally Invasive Esthetics

BACKGROUND/AIM

To overcome the natural visual consequences of the physiological aging process, the use of biodegradable fillers made of hyaluronic acid or sodium carboxymethyl cellulose is increasingly popular in modern esthetic medicine. Clinicians can choose from a wide range of fillers with variable compositions and rheological properties, and therefore with different application areas and injection depths. The aim of this study was to analyze and compare the most commonly used fillers for facial augmentation regarding their in vitro biocompatibility and to find potential correlations to their rheological properties.

MATERIALS AND METHODS

In the present study, direct and indirect in vitro cytotoxicity analysis according to DIN EN ISO 10993-5 were performed on 39 different filler materials for facial augmentation.

RESULTS

All fillers analyzed in this study overall showed satisfactory results in the direct and indirect cytocompatibility tests. While no material was outside the threshold values in the 2,3-bis-(2-methoxy-4-nitro-5-sulphenyl)-(2H)-tetrazolium-5-carboxanilide (XTT) cell viability and bromodeoxyuridine (BrdU) cell proliferation assays or in the live-dead staining, only 7 out of the 39 fillers reached the required values in the lactate dehydrogenase assay.

CONCLUSION

All biodegradable fillers examined in this study were found to be sufficiently cytocompatible. Although the qualitative analysis of the test results showed differences between the fillers, no concrete correlation between test performance and composition or manufacturer of the fillers was found. Future efforts are required to provide clinicians with even better support in choosing the right filler for optimal outcome and patient satisfaction.

Role of Hyperbaric Oxygen in Filler-Induced Vascular Occlusion

INTRODUCTION

The rising incidence of filler-induced vascular complications in the context of aesthetic procedures necessitates a thorough assessment of therapeutic options. Hyperbaric oxygen therapy (HBOT) has emerged as a potential intervention for filler-induced vascular occlusion (FIVO), although optimal dosing and timing remain undefined.

METHODS

This review explores the pathophysiology of FIVO and elucidates HBOT's multifaceted role in salvaging ischemic tissue. The physical and biochemical mechanisms of HBOT, including its vasodilatory, anti-spasmodic, and anti-inflammatory effects, are examined.

RESULTS

HBOT serves as an adjunctive therapy in FIVO management, emphasizing timely intervention, adherence to specific pressures (two atmosphere absolute), and session durations (60 minutes) to optimize efficacy and minimize complications. While existing HBOT protocols for compromised grafts provide insights, standardized guidelines for FIVO are lacking.

CONCLUSION

HBOT enhances tissue oxygenation, modulates reactive oxygen species, and influences angiogenesis and hypoxia response. However, it does not replace key treatment protocols for filler vascular complications. Further research and standardized protocols are warranted to define HBOT's definitive role in mitigating filler-induced vascular complications. Level of Evidence IV 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 .

Efficacy and Safety of Type III Collagen Lyophilized Fibers Using Mid-to-Deep Dermal Facial Injections for the Correction of Dynamic Facial Wrinkles

BACKGROUND

This study aimed to evaluate the therapeutic efficacy and safety of injecting Type III collagen lyophilized fibers into the mid-to-deep layers of the facial dermis to ameliorate dynamic facial wrinkles.

METHODS

In this retrospective analysis, clinical data were collected from patients exhibiting dynamic facial wrinkles (encompassing frown lines, forehead lines, and crow's feet) with a wrinkle severity rating scale (WSRS) score of 3 or higher. In the control group, 75 participants received collagen implant injections into the mid-to-deep facial dermal layers, whereas 76 participants in the experimental group received injections of Type III collagen lyophilized fibers in similar layers. The study analyzed and compared clinical efficacy, WSRS score alterations, patient satisfaction, and safety profiles between the groups over the 30-day and 90-day treatment periods.

RESULTS

At the 30-day mark, the therapeutic efficacy was not significantly different between the two groups (P > 0.05). However, at 90 days, the treatment efficacy in the experimental group surpassed that in the control group, showing a statistically significant difference (P < 0.05). After 30 days of treatment, the WSRS score improvement in the experimental group was significantly superior to that in the control group (P < 0.05). Conversely, at the 90-day mark, the results revealed no significant variation in WSRS score improvements between the two groups (P > 0.05). Regarding treatment satisfaction among researchers and participants post-30 and 90-day treatment in both groups, no statistically significant differences were observed (P > 0.05). Similarly, the incidence of adverse reactions between the groups was not statistically significant (P > 0.05).

CONCLUSIONS

Injections of lyophilized type III collagen fibers into the mid-to-deep layers of the facial dermis have a definitive therapeutic effect on dynamic facial wrinkles. This treatment not only substantially diminishes wrinkle severity but also has a commendable safety profile.

LEVEL OF EVIDENCE I

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 .

Dual Functionalization of Hyaluronan Dermal Fillers with Vitamin B3: Efficient Combination of Bio-Stimulation Properties with Hydrogel System Resilience Enhancement

Hyaluronic acid (HA) hydrogels are commonly used for facial dermal filling and for alternative medical aesthetic purposes. High diversity exists in commercial formulations, notably for the optimization of finished product stability, functionality, and performance. Polyvalent ingredients such as calcium hydroxylapatite (CaHA) or vitamin B3 (niacinamide) are notably used as bio-stimulants to improve skin quality attributes at the administration site. The aim of the present study was to perform multi-parametric characterization of two novel cross-linked dermal filler formulas (HAR-1 "Instant Refine" and HAR-3 "Maxi Lift") for elucidation of the various functional impacts of vitamin B3 incorporation. Therefore, the HAR products were firstly comparatively characterized in terms of in vitro rheology, cohesivity, injectability, and resistance to chemical or enzymatic degradation (exposition to H2O2, AAPH, hyaluronidases, or xanthine oxidase). Then, the HAR products were assessed for cytocompatibility and in vitro bio-stimulation attributes in a primary dermal fibroblast model. The results showed enhanced resilience of the cohesive HAR hydrogels as compared to JUVÉDERM® VOLBELLA® and VOLUMA® reference products in a controlled degradation assay panel. Furthermore, significant induction of total collagen synthesis in primary dermal fibroblast cultures was recorded for HAR-1 and HAR-3, denoting intrinsic bio-stimulatory effects comparable or superior to those of the Radiesse® and Sculptra™ reference products. Original results of high translational relevance were generated herein using robust and orthogonal experimental methodologies (hydrogel degradation, functional benchmarking) and study designs. Overall, the reported results confirmed the dual functionalization role of vitamin B3 in cross-linked HA dermal fillers, with a significant enhancement of hydrogel system stability attributes and the deployment of potent bio-stimulatory capacities.

Resolve and dissolve-An ultrasound-guided investigation on the effects of hyaluronidase on different soft tissue fillers

BACKGROUND

Nonsurgical cosmetic procedures, particularly the use of hyaluronic acid (HA)-based soft tissue fillers, are becoming increasingly popular. This trend has catalyzed the development of a plethora of HA-based products differing in product characteristics, thereby catering to an ever-widening spectrum of aesthetic applications. However, complications rise concomitant with the increasing number of procedures. Among the strategies to manage such adverse events is the enzymatic breakdown with hyaluronidase.

OBJECTIVE

To analyze the response of different HA-based soft tissue filler materials to hyaluronidase injections.

METHODS

A total of 11 different HA-based soft tissue fillers were evaluated using noninvasive ultrasound imaging to assess their behavior in response to hyaluronidase injections. The HA-based soft tissue fillers were categorized according to their product characteristics into a structuring, volumizing, and lip volumizing group. Standardized injections of 0.2 cc were performed in chicken breast to simulate human tissue. Ultrasound measurements of width, height, and calculated volume were performed immediately after filler injection, 1 h and 24 h following hyaluronidase injection.

RESULTS

Regardless of the soft tissue filler analyzed, the most significant volume reduction occurred within the first h after applying hyaluronidase, with a 64.1% decrease from the initial volume. After 24 h, the total volume reduction reached 81.7%. No statistically significant differences were found when comparing the three groups at each follow-up time period, except for the height measurement after 1 h. While width was statistically significant in all groups between the investigated follow-up groups, the volume reduction was only statistically significant in the groups with the highest and second highest G' values (i.e., Group 1-structuring, Group 2-volumizing).

CONCLUSION

The effectiveness of hyaluronidase in dissolving HA-based fillers is initially independent of product characteristics of HA-based fillers such as G-prime, with increased efficacy in fillers with higher G-prime values, as evidenced by significant volume reductions in such groups.

Profiloplasty and facial contouring with injectables: A holistic, practical, and user-friendly approach

BACKGROUND

Expansion of the aesthetic treatment armamentarium with novel injectable products has greatly improved our ability to reshape and enhance the facial profile. However, full-face "profiloplasty" with injectables remain a nascent concept and is insufficiently considered in daily practice. While techniques have been widely published for treating the individual facial areas that constitute an attractive profile-including the forehead, nose, lips, jawline, and chin-the literature remains fragmented on more universal methods for profile improvement.

AIMS

To collate disparate knowledge on profile optimization with injectables, and define a holistic, practical, and user-friendly approach to profiloplasty and facial contouring.

METHODS

Consideration is given to key anatomical aspects and the changes that occur with age; patient assessment parameters for planning profiloplasty; and the technical specifications, product selection, and essential safety considerations for minimizing the risk of complications and optimizing the effectiveness of treatment.

RESULTS

Relevant case studies are presented.

CONCLUSIONS

Holistic approaches of this type are essential if we are to maximize the potential of full-face treatment with injectables-both now and in the future.

The rheology of injectable hyaluronic acid hydrogels used as facial fillers: A review

Injectable hyaluronic acid (HA) hydrogels have been popularized in facial aesthetics as they provide a long-lasting effect, low risk of complications, allergenicity tests are not required before application and can be easily removed by the action of hyaluronidases. On the other hand, the development of these systems requires in-depth studies of chemical mechanisms involved in hydrogel formation. Ideal dermal fillers should temporarily fluidize during extrusion through the needle and quickly recover their original shape after application. Hydrogels with more elastic properties, for example, are difficult to inject while viscous materials are too liquid. A balance between both properties should be achieved. Each region of the face requires products with distinct rheological properties. High G' dermal fillers are preferable for deeper wrinkles whereas the counterpart with lower values of G' is more indicated in superficial wrinkles or lip augmentation. Factors such as molecular weight and concentration of HA, pH, type and concentration of the crosslinking agent, particle size, crosslinking reaction time and crosslinking agent/polysaccharide ratio should be modulated to achieve specific rheological properties. In this review, the effect of each variable is discussed in detail to guide the rational development of new dermal fillers.

Comprehensive Evaluation of Injectability Attributes in OxiFree™ Dermal Fillers: MaiLi® Product Variants and Clinical Case Reports

Dermal filler injectability is a critical factor for commercial product adoption by medical aesthetic professionals and for successful clinical administration. We have previously reported (in vitro and ex vivo) cross-linked hyaluronic acid (HA)-based dermal filler benchmarking in terms of manual and automated injectability requirements. To further enhance the function-oriented product characterization workflows and the clinical relevance of dermal filler injectability assessments, the aim of this study was to perform in vivo evaluations. Therefore, several variants of the MaiLi® product range (OxiFree™ technology) were characterized in vitro and in vivo in terms of injectability attributes, with a focus on hydrogel system homogeneity and ease of injection. Firstly, standardized in vitro assays were performed in SimSkin® cutaneous equivalents, with variations of the clinical injector, injection site, and injection technique. Then, automated injections in SimSkin® cutaneous equivalents were comparatively performed in a texture analysis setup to obtain fine-granulometry injection force profile results. Finally, five female participants were recruited for the in vivo arm of the study (case reports), with variations of the clinical injector, injection site, and injection technique. Generally, the obtained quantitative force values and injection force profiles were critically appraised from a translational viewpoint, based on discussions around the OxiFree™ manufacturing technology and on in-use specialized clinician feedback. Overall, the present study outlined a notable level of homogeneity across the MaiLi® product range in terms of injectability attributes, as well as consistently high ease of administration by medical aesthetic clinicians.

Nonsurgical rhinoplasty using the hyaluronic acid filler VYC-25L: Safety and patient satisfaction in a retrospective analysis of 492 patients

BACKGROUND

Aesthetic treatment of the nose with hyaluronic acid (HA) fillers is increasingly popular but carries a small risk of major complications. Large patient cohorts are required to better understand this risk.

AIMS

To evaluate safety and patient satisfaction in a large series of nonsurgical rhinoplasty treatments with the HA filler, VYC-25L, in "real world" clinical practice.

METHODS

This was a retrospective analysis of consecutive adult patients undergoing nonsurgical rhinoplasty with VYC-25L by a single injector between January 2020 and July 2022. All patients received initial treatment (typically ~0.3-0.5 mL of filler) and touch-up at 4-6 weeks (~0.1-0.3 mL). Safety data were collected throughout a mean follow-up of 11.1 months. Patient satisfaction was assessed using the FACE-Q Satisfaction with Nose and Satisfaction with Outcome questionnaires.

RESULTS

A total of 492 patients were included (984 treatment sessions including touch-ups). Of these, 467 (94.9%) were female and the mean age was 30.0 years. All treatments were associated with early transient edema; other adverse events included bruising (n = 123; 25%), residual asymmetry (n = 18; 3.7%), and suspected localized vascular occlusion (n = 3; 0.6%). The latter cases were easily resolved with hyaluronidase injection plus oral steroid and aspirin. No patients experienced infection, necrosis, blindness, lumps, granuloma, or delayed-onset nodules. Mean Rasch-transformed FACE-Q scores were 90.2% for Satisfaction with Nose and 99.2% for Satisfaction with Outcome.

CONCLUSIONS

In a large cohort of patients treated in routine practice based on a systematic approach, nonsurgical rhinoplasty with VYC-25L was safe and effective.

A Retrospective Analysis of Safety in Participants Treated with a Hybrid Hyaluronic Acid and Calcium Hydroxyapatite Filler

Background

Limited long-term safety data are published on HA/CaHA/L, a hybrid dermal filler combining hyaluronic acid (HA), calcium hydroxyapatite (CaHA), and lidocaine (L).

Methods

This retrospective multicenter study assessed treatment-emergent adverse events (TEAEs) in adults treated with HA/CaHA/L. The full analysis set (FAS) included eligible consented adults (N = 403); the long-term safety analysis (LTSA) set included FAS participants with greater than or equal to 12-months HA/CaHA/L exposure (n = 243).

Results

Participants were majority female (94.0%), with Fitzpatrick skin phototypes II/III (80.1%) and a mean age of 50.1 years. Most participants (86.4%) received one HA/CaHA/L treatment. The median time between participants' first HA/CaHA/L treatment and chart review was 15.4 months. Participants received a mean of 2.2 mL (0.5-8.9 mL) filler per treatment. Treated areas were predominantly malar (71.2%) and mandible (69.7%) regions. Most participants (95.0%) had one or more aesthetic treatments other than HA/CaHA/L [eg, other dermal fillers (84.1%), botulinum toxin (63.3%)]. Nineteen (4.7%) FAS participants had 20 documented TEAEs; most (3.5%, n = 14 participants) were mild in severity. Twelve TEAEs in 11 participants (2.7%) were related to HA/CaHA/L: induration (three, 0.7%), edema (3, 0.7%), and implant site nodules (five, 1.2%), which were noninflammatory and likely related to product placement. Among the LTSA, 15 (6.2%) participants had 16 documented TEAEs (six edema, five implant site nodules, one inflammation, three skin induration, one hypersensitivity); most were mild in severity. Nine TEAEs in eight participants (3.3%) were HA/CaHA/L-related. No treatment-emergent serious AEs were reported.

Conclusion

The data from this noninterventional retrospective study support the favorable longer term (>12 month) safety profile of HA/CaHA/L.

The Efficacy and Safety of Hyaluronic Acid Injection in Tear Trough Deformity: A Systematic Review and Meta-analysis

BACKGROUND

Hyaluronic acid (HA) injection is an effective method to correct tear trough deformity. Nevertheless, the quantitative data of cosmetic results and complications of HA injection in tear troughs remained unemployed. The purpose of this meta-analysis was to synthesize the current quantitative data on the aesthetic outcomes and adverse effects of tear trough deformity correction with HA injection.

METHODS

This meta-analysis consulted PubMed, Embase, Web of Science, Scopus and Cochrane databases based on the search terms published before September 2022. Data extracted was analyzed to evaluate the satisfaction rates and complications of HA injection. Meta-analysis was performed using the random-effect model for overall and subgroup analysis.

RESULTS

This meta-analysis comprised 31 reports involving 2556 participants. The pooled overall satisfaction rate was 91.0% (95% CI 84.9-95.7%). The pooled rates of swelling/edema and bruising/ecchymosis were 19.2% (95% CI 10.4-29.9%) and 18.4% (95% CI 10.1-28.4%), respectively. The pooled rates of redness/erythema, contour irregularity/lump and blue discoloration/Tyndall effect were 7.1% (95% CI 1.5-15.6%), 5.3% (95% CI 1.8-10.2%) and 0.9% (95% CI 0.0-2.5%), respectively.

CONCLUSIONS

The present meta-analysis manifested a low risk of complication rate and a high satisfaction rate in tear trough rejuvenation with HA injection.

LEVEL OF EVIDENCE I

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 .

Clinical Perspectives on the Injectability of Cross-Linked Hyaluronic Acid Dermal Fillers: A Standardized Methodology for Commercial Product Benchmarking with Inter-Injector Assessments

The injectability of cross-linked hyaluronic acid (HA) dermal fillers is influenced by polymer concentration, polymer cross-linking type and degree, the presence of lidocaine or other functional excipients, types of syringes, and injection techniques. Finished product injectability constitutes a critical quality attribute for clinical injectors, as it strongly influences product applicability and ease of use in aesthetic medicine. While injectable product extrusion force specifications are provided by the respective device manufacturers, the qualitative informative value of such datasets is low for injectors wishing to compare product brands and technologies from an injectability standpoint. Therefore, the present study comparatively assessed 28 cross-linked HA dermal fillers (JUVÉDERM®, Restylane®, BELOTERO®, TEOSYAL RHA®, and STYLAGE® brands) using various injectability benchmarking setups for enhanced clinical-oriented relevance. Manual product injections were performed by three specialized and experienced clinicians, whereas automatic product extrusion was performed using a Texture Analyzer instrument. The various hydrogel products were injected into ex vivo human skin and into SimSkin® cutaneous equivalents to appropriately account for injection-related counterpressure. The injectability results revealed important variability between and within product brands, with a strong influence of the local anesthetic lidocaine, HA contents, and needle gauge size. Critical appraisals of the investigated products were performed, notably from manufacturing process-based and clinical ease of application-based standpoints, centered on respective experimental injectability quality levels. Generally, it was confirmed that each HA-based dermal filler product requires specific expertise for optimal injection, mainly due to differing viscoelastic characteristics and injectability attributes. Overall, the present study set forth evidence-based and clinical-oriented rationale elements confirming the importance for injectors to work with injectable products with which they are experienced and comfortable to optimize clinical results.

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

Evaluation of the Hydrophilic, Cohesive, and Physical Properties of Eight Hyaluronic Acid Fillers: Clinical Implications of Gel Differentiation

Background

Hyaluronic acid (HA) fillers are used to treat an array of aesthetic indications. Proper filler selection is paramount for successful patient outcomes. However, many important physiochemical and physical properties that impact HA gel behavior remain undefined.

Purpose

To evaluate the hydrophilicity, cohesivity and particle size of eight commercial HA fillers manufactured by either Non-Animal Stabilized Hyaluronic Acid (NASHA) or Optimal Balance Technology (OBT) techniques.

Methods and Materials

Three individual in vitro experiments were performed to assess HA swelling capacity, cohesion, and particle size. Image analyses, blinded evaluation using the Gavard-Sundaram Cohesivity Scale, and laser diffraction technology were utilized, respectively.

Results

Compared to fillers manufactured with NASHA technology, OBT products demonstrated greater swelling capacity, cohesion, and wider particle size distributions. Strong positive correlations between swelling factor, degree of cohesivity, and increasing widths of the particle size distributions were observed.

Conclusions

The hydrophilicity, cohesivity and particle size distributions vary among HA fillers manufactured with different techniques. The creation of new labels identifying products based on their unique combination of physiochemical and physical characteristics may help guide appropriate selection of HA fillers to optimize patient outcomes.

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 .

Choosing Juvéderm Volux™ to chin augmentation: Case report and flowchart for clinical evaluation

INTRODUCTION

The development of filler biomaterials with high hyaluronic acid concentrations, cohesiveness, and elastic modulus has become an option for chin augmentation, as the balance of these rheological properties promotes high lifting capacity, providing minimally invasive perceptible improvements in patient appearance.

PRESENTATION OF CASE

The present study reviewed clinical and anatomical aspects of patients referred for chin augmentation and created a flowchart to assertively diagnose patients with an indication of Juvéderm® Volux™ for defining the lower third of the face.

DISCUSSION

The chin is vital for facial proportions and attractiveness perception. Its relevance to facial appearance is noticed the most when chin size is less than ideal, making other facial areas seem larger or smaller. The adjacent soft tissues of the neck and jaw appear prematurely aged when chin projection or width is inadequate. Hyaluronic acid-based fillers have a confirmed history of safe and effective use for treating facial volume loss or deficiency.

CONCLUSION

Juvéderm® Volux™ is a safe, effective, and long-lasting alternative for restoring and creating facial volume and sculpting, shaping, and contouring the chin and jaw.

Response of 21 Hyaluronic Acid Fillers to Recombinant Human Hyaluronidase

Background

One benefit of hyaluronic acid fillers is the ability to dissolve them using hyaluronidase. With the increasing number of fillers entering the market, it is crucial to understand each of these fillers' responsiveness to hyaluronidase.

Methods

Twenty-one hyaluronic acid fillers of 0.2 mL aliquots each were placed on slides. Twenty units of recombinant human hyaluronidase were injected into the aliquots every 30 minutes for a total of 120 units recombinant human hyaluronidase injected over 3 hours. With each injection, videos and photographs were taken from bird's eye and lateral views to measure aliquot height. Stirring videos were graded by three oculoplastic surgeons, and these grades were used to categorize each filler's responsiveness.

Results

Restylane Lyft, Restylane-L/Eyelight, and Resilient Hyaluronic Acid (RHA) 1/Redensity were the least resistant. The moderately resistant group comprised of Restylane Silk, Juvéderm Volbella, Revanesse Versa/Lips, and Belotero Balance on the less resistant side to Juvéderm Vollure, RHA 2, Restylane Contour, Juvéderm Ultra, Restylane Refyne, Belotero Intense, Restylane Kysse, RHA 3, Juvéderm Ultra Plus, and Restylane Defyne on the more resistant side. The most resistant were RHA 4, Juvéderm Voluma, Belotero Volume, and Juvéderm Volux. The most resistant fillers required 120 units of hyaluronidase per 0.2 mL filler to dissolve.

Conclusions

With the increasing popularity of fillers comes the increasing need to dissolve them for both ischemic and nonischemic complications. The majority of hyaluronic acid fillers available on the market are very resistant to hyaluronidase, which must be considered when determining the amount of hyaluronidase to dissolve a particular filler.

Improved Patient Satisfaction With Skin After Treatment of Cheek Skin Roughness and Fine Lines With VYC-12L: Participant-Reported Outcomes From a Prospective, Randomized Study

BACKGROUND

VYC-12L is a hyaluronic acid filler to improve skin quality. A prospective study showed safety and effectiveness of VYC-12L for improving cheek skin smoothness and fine lines.

OBJECTIVES

To report participant-reported outcomes, subgroup analyses, and physician experience from the prospective study.

METHODS

Adults with moderate to severe Allergan Cheek Skin Smoothness (ACSS) scale scores were randomized 2:1 to VYC-12L or control (no treatment with optional treatment). Participant assessments included FACE-Q Satisfaction With Skin, FACE-Q Appraisal of Lines, natural look and feel, the Global Aesthetic Improvement Scale (GAIS), and safety. Subgroup analyses examined ACSS responder rate (≥1-grade improvement from baseline to 1 month).

RESULTS

FACE-Q Satisfaction With Skin overall mean scores improved from baseline to 1 month posttreatment by 32.0 and 1.4 in the VYC-12L and control groups, respectively. FACE-Q Appraisal of Lines overall mean scores improved from baseline to 1 month posttreatment by 23.3 and 0.4 in VYC-12L and control, respectively. Treated participants had high median scores (≥9.0) of natural look and feel of their cheek skin. GAIS responder rate was high at Month 1 (85.5%; 95% CI, 79.3%-91.7%) and through Month 6 (83.1%; 95% CI, 76.5%-89.7%). Mean participant-rated pain scores were low (<3). The most common injection site reactions were redness, swelling, and lumps/bumps; most resolved within 3 days. Subgroup analyses showed significant differences in ACSS responder rate between VYC-12L and control groups 1 month posttreatment. Physician injectors reported that VYC-12L was easily injected at the superficial skin and integrated quickly.

CONCLUSIONS

VYC-12L treatment produced significant improvements in satisfaction with skin and cheek skin smoothness, as measured by participant-reported outcome measures.

LEVEL OF EVIDENCE: 2

Investigation of Crosslinking Parameters and Characterization of Hyaluronic Acid Dermal Fillers: From Design to Product Performances

Despite process similarities, distinctive manufacturing technologies offer hyaluronic acid dermal fillers with different in vitro physicochemical and rheological properties due to peculiar crosslinked hydrogel networks. A better understanding of dermal filler properties could provide specific clinical indications and expectations with more accurate performance correlations. In this study, with an emphasis on the degree of modification, hyaluronic acid concentration and molecular weight, these process parameters were able to modulate dermal filler properties, especially rheology. Moreover, an extensive characterization of commercial hyaluronic acid injectables of the Hyal System line was described to present product properties and help to elucidate related clinical effects. Standardized methodologies were applied to correlate in vitro parameters with feasible clinical indications. In view of an optimized dermal filler design, the results of the extrudability measurements allowed the quantification of the effect of hydrogel composition, rheological properties and needle size on injectability. Composition, dynamic viscosity and needle size showed an impactful influence on hydrogel extrudability. Finally, the positive influence of 200 KDa hyaluronic acid in comparison to fragments of ether-crosslinked hyaluronic acid on fibroblast recognition were shown with a migration assay.

Skin Cell and Tissue Responses to Cross-Linked Hyaluronic Acid in Low-Grade Inflammatory Conditions

Hyaluronic acid (HA), used in a variety of medical applications, is associated in rare instances to long-term adverse effects. Although the aetiology of these events is unknown, a number of hypotheses have been proposed, including low molecular weight of HA (LMW-HA) in the filler products. We hypothesized that cross-linked HA and its degradation products, in a low-grade inflammatory microenvironment, could impact immune responses that could affect cell behaviours in the dermis. Using two different cross-linking technologies VYC-15L and HYC-24L+, and their hyaluronidase-induced degradation products, we observed for nondegraded HA, VYC-15L and HYC-24L+, a moderate and transient increase in IL-1β, TNF-α in M1 macrophages under low-grade inflammatory conditions. Endothelial cells and fibroblasts were preconditioned using inflammatory medium produced by M1 macrophages. 24 h after LMW-HA fragments and HA stimulation, no cytokine was released in these preconditioned cells. To further characterize HA responses, we used a novel in vivo murine model exhibiting a systemic low-grade inflammatory phenotype. The intradermal injection of VYC-15L and its degradation products induced an inflammation and cell infiltration into the skin that was more pronounced than those by HYC-24L+. This acute cutaneous inflammation was likely due to mechanical effects due to filler injection and tissue integration rather than its biological effects on inflammation. VYC-15L and its degradation product potentiated microvascular response to acetylcholine in the presence of a low-grade inflammation. The different responses with 2D cell models and mouse model using the two tested cross-linking HA technologies showed the importance to use integrative complex model to better understand the effects of HA products according to inflammatory state.

Hyaluronic Acid: A Powerful Biomolecule with Wide-Ranging Applications-A Comprehensive Review

Hyaluronic acid (HA) is a glycosaminoglycan widely distributed in the human body, especially in body fluids and the extracellular matrix of tissues. It plays a crucial role not only in maintaining tissue hydration but also in cellular processes such as proliferation, differentiation, and the inflammatory response. HA has demonstrated its efficacy as a powerful bioactive molecule not only for skin antiaging but also in atherosclerosis, cancer, and other pathological conditions. Due to its biocompatibility, biodegradability, non-toxicity, and non-immunogenicity, several HA-based biomedical products have been developed. There is an increasing focus on optimizing HA production processes to achieve high-quality, efficient, and cost-effective products. This review discusses HA's structure, properties, and production through microbial fermentation. Furthermore, it highlights the bioactive applications of HA in emerging sectors of biomedicine.

Filler-based correction of tear trough depressions and eye bags in Japanese patients: A classification system and treatment algorithm

BACKGROUND

Tear trough depressions are widely treated with fillers. However, it is questionable whether the same strategies can always be used for Caucasian and Japanese patients, owing to differences in bone and skin structures and epithelial thickness.

AIMS

To assess a novel classification system and treatment algorithm for correcting tear trough depressions and eye bags in Japanese patients.

METHODS

Tear trough depressions can be classified into three types according to the presence or absence of a "negative vector" based on retrusion of the maxilla relative to the anterior corneal surface, with or without eye-bag protrusion when smiling. Type 1 patients (without the negative vector) can be treated simply by filling the depression in the tear trough and the palpebromalar groove region. Type 2 patients (with a negative vector and no eye-bag protrusion on smiling) also require volume restoration in the mid-cheek (deep medial cheek fat, suborbicularis oculi fat, and pre-maxillary space); this not only enables volume recovery but also compensates for maxillary deficiency. Type 3 patients (with a negative vector and eye-bag protrusion on smiling) require an additional step, based on placing a filler in front of the eye bags and pushing orbital fat backward.

RESULTS

Case presentations demonstrate the utility of the techniques involved.

CONCLUSIONS

This system provides a simple and practical method for classifying and treating Japanese patients with tear trough depressions and eye bags. Further studies are warranted.

Bridging a Century-Old Problem: The Pathophysiology and Molecular Mechanisms of HA Filler-Induced Vascular Occlusion (FIVO)—Implications for Therapeutic Interventions

Biocompatible hyaluronic acid (HA, hyaluronan) gel implants have altered the therapeutic landscape of surgery and medicine, fostering an array of innovative products that include viscosurgical aids, synovial supplements, and drug-eluting nanomaterials. However, it is perhaps the explosive growth in the cosmetic applications of injectable dermal fillers that has captured the brightest spotlight, emerging as the dominant modality in plastic surgery and aesthetic medicine. The popularity surge with which injectable HA fillers have risen to in vogue status has also brought a concomitant increase in the incidence of once-rare iatrogenic vaso-occlusive injuries ranging from disfiguring facial skin necrosis to disabling neuro-ophthalmological sequelae. As our understanding of the pathophysiology of these injuries has evolved, supplemented by more than a century of astute observations, the formulation of novel therapeutic and preventative strategies has permitted the amelioration of this burdensome complication. In this special issue article, we review the relevant mechanisms underlying HA filler-induced vascular occlusion (FIVO), with particular emphasis on the rheo-mechanical aspects of vascular blockade; the thromboembolic potential of HA mixtures; and the tissue-specific ischemic susceptibility of microvascular networks, which leads to underperfusion, hypoxia, and ultimate injury. In addition, recent therapeutic advances and novel considerations on the prevention and management of muco-cutaneous and neuro-ophthalmological complications are examined.