Comparative study of hyaluronic acid fillers by in vitro and in vivo testing

Self-crossing hyaluronic acid filler with combination use of polydioxanone thread in minipig model

INTRODUCTION

The advances of self-crossing hyaluronic acid (SC-HA) fillers combination use with polydioxanone thread in minipigs were examined for compatibility, effectiveness, and immune response.

MATERIALS AND METHODS

A 12-week experiment was conducted using 6 minipigs (3 male and 3 female each) to evaluate the effects of SC-HA filler. The molecular weight of SC-HA filler was fixed at 200 kDa and alternative storage modulus of G80, G250, and G500 were examined. The procedure involved injecting SC-HA filler and polydioxanone threads into the skin tissue of anesthetized minipigs, and tissue sampling after 1 month (three minipigs), and 3 months (three minipigs) for histological staining and analysis. The immune reaction was observed during the experiment.

RESULTS

The practitioner reported it was easy to inject the SC-HA filler in combination with polydioxanone threads. All four storage modulus of SC-HA fillers were injectable within the polydioxanone thread containing cannula. Also, during the procedure, there were no immune responses at the treated sites. The results of the histological tissue examination confirmed that there was no chemical interaction between SC-HA filler and the existing polydioxanone thread, and it was observed that SC-HA filler was more uniformly distributed within the tissue with lower storage modulus, resulting in a higher production of collagen in the surrounding filler. When combined with scaffold polydioxanone thread, the scaffold polydioxanone thread helped spread the filler evenly, resulting in a more evenly distributed collagen around the filler.

CONCLUSION

Today, the combination therapy of filler and polydioxanone thread in one procedure is challenging due to the high viscosity of conventional fillers. However, this study confirmed that combination therapy of filler and polydioxanone thread is possible with SC-HA fillers. Additionally, it was found that polydioxanone thread does not seem to interfere with the crosslinking reaction of SC-HA filler, and if used with a higher pH of polydioxanone, it may enhance the cross-linking reaction and achieve a higher viscosity value. Finally, the study resulted in the idea of concrete as SC-HA filler and reinforcing rod for polydioxanone thread.

Combination of Machine Learning and Raman Spectroscopy for Determination of the Complex of Whey Protein Isolate with Hyaluronic Acid

Macromolecules and their complexes remain interesting topics in various fields, such as targeted drug delivery and tissue regeneration. The complex chemical structure of such substances can be studied with a combination of Raman spectroscopy and machine learning. The complex of whey protein isolate (WPI) and hyaluronic acid (HA) is beneficial in terms of drug delivery. It provides HA properties with the stability obtained from WPI. However, differences between WPI-HA and WPI solutions can be difficult to detect by Raman spectroscopy. Especially when the low HA (0.1, 0.25, 0.5% w/v) and the constant WPI (5% w/v) concentrations are used. Before applying the machine learning techniques, all the collected data were divided into training and test sets in a ratio of 3:1. The performances of two ensemble methods, random forest (RF) and gradient boosting (GB), were evaluated on the Raman data, depending on the type of problem (regression or classification). The impact of noise reduction using principal component analysis (PCA) on the performance of the two machine learning methods was assessed. This procedure allowed us to reduce the number of features while retaining 95% of the explained variance in the data. Another application of these machine learning methods was to identify the WPI Raman bands that changed the most with the addition of HA. Both the RF and GB could provide feature importance data that could be plotted in conjunction with the actual Raman spectra of the samples. The results show that the addition of HA to WPI led to changes mainly around 1003 cm-1 (correspond to ring breath of phenylalanine) and 1400 cm-1, as demonstrated by the regression and classification models. For selected Raman bands, where the feature importance was greater than 1%, a direct evaluation of the effect of the amount of HA on the Raman intensities was performed but was found not to be informative. Thus, applying the RF or GB estimators to the Raman data with feature importance evaluation could detect and highlight small differences in the spectra of substances that arose from changes in the chemical structure; using PCA to filter out noise in the Raman data could improve the performance of both the RF and GB. The demonstrated results will make it possible to analyze changes in chemical bonds during various processes, for example, conjugation, to study complex mixtures of substances, even with small additions of the components of interest.

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.

In Vitro Comparison Between Ovine and Human Recombinant Hyaluronidase on Hyaluronic Acid Fillers

Introduction: Injectable hyaluronic acid (HA) fillers are commonly used to provide tissue augmentation and combat the effects of facial aging. Ovine and human recombinant formulations of the enzyme hyaluronidase (HAse) are used interchangeably; however, it is unknown if there exists a difference in their ability to degrade HA. Objective: To compare rates at which ovine and human recombinant forms of HAse degrade various HA fillers in vitro. Methods: Increasing amounts of either ovine or human recombinant HAse were added to fixed amounts of nine unique HA filler products. Degradation rates were then analyzed using a colorimetric method by measuring absorbance levels of degraded product. Results: Human recombinant HAse degraded more HA when compared with ovine HAse overall (p = 0.014, confidence interval [-0.015 to -0.0018]). Conclusions: Human recombinant HAse was found to be more effective on average in degrading HA fillers when compared with ovine HAse in vitro.

Early ultrasound for diagnosis and treatment of vascular adverse events with hyaluronic acid fillers

BACKGROUND

Hyaluronic acid fillers are known for a reliable safety profile, but complications do occur, even serious vascular adverse events.

OBJECTIVE

To improve the treatment outcome after a vascular adverse event with use of hyaluronic acid filler treatments.

METHODS

Duplex ultrasonography is used to detect the hyaluronic acid filler causing the intra-arterial obstruction.

RESULTS

If treated in time, 1 single treatment of ultrasonographically guided injections of hyaluronidase into the filler deposit will prevent skin necrosis.

CONCLUSION

Because the use of duplex ultrasonography adds extra essential information, its use may become an integral part of the prevention and treatment of injection adverse events.

Transcriptomic Analysis in Human 3D Skin Model Injected with Resorbable Hyaluronic Acid Fillers Reveals Foreign Body Response

Usage of injectable dermal fillers applied for aesthetic purposes has extensively increased over the years. As such, the number of related adverse reactions has increased, including patients showing severe complications such as product migration, topical swelling and inflammatory reactions of the skin. In order to understand the underlying molecular events of these adverse reactions we performed a genome-wide gene expression study on the multi-cell type human Phenion® Full-Thickness Skin Model exposed to five experimental hyaluronic acid (HA) preparations with increasing cross-linking degree, four commercial fillers from Perfectha®, and non-resorbable filler Bio-Alcamid®. In addition, we evaluated whether cross-linking degree or particle size of the HA-based fillers could be associated with the occurrence of adverse effects. In all cases, exposure to different HA fillers resulted in a clearly elevated gene expression of cytokines and chemokines related to acute inflammation as part of the foreign body response. Furthermore, for one experimental filler genes of OXPHOS complexes I-V were significantly down-regulated (adjusted p-value < 0.05), resulting in mitochondrial dysfunction which can be linked to over-expression of pro-inflammatory cytokines TNFα and IL-1β and chemokine CCL2. Our hypothesis that cross-linking degree or particle size of the HA-based fillers is related to the biological responses induced by these fillers could only partially be confirmed for particle size. In conclusion, our innovative approach resulted in gene expression changes from a human 3D skin model exposed to dermal fillers that mechanistically substantiate aforementioned adverse reactions, and thereby adds to the weight of evidence that these fillers may induce inflammatory and fibrotic responses.

The Rheology and Physicochemical Characteristics of Hyaluronic Acid Fillers: Their Clinical Implications

Hyaluronic acid (HA) fillers have become the most popular material for facial volume augmentation and wrinkle correction. Several filler brands are currently on the market all around the world and their features are extremely variable; for this reason, most users are unaware of their differences. The study of filler rheology has become a wellspring of knowledge, differentiating HA fillers, although these properties are not described thoroughly by the manufacturers. The authors of this review describe the more useful rheological properties that can help clinicians understand filler characteristics and the likely correlation of these features with clinical outcomes.

Quantitative Evaluation of Volume Augmentation and Durational Changes in the Anteromedial Cheek with Hyaluronic Acid Fillers Using Three-Dimensional Measurement: 2-Year Results from a Comparative Split-Face Study

SUMMARY

Hyaluronic acid fillers are widely used for the augmentation of facial soft tissues. Hyaluronic acid fillers can be monophasic or biphasic and have different characteristics, especially regarding volumetric effects and maintenance potential. However, there is paucity of long-term quantitative and objective data on clinical outcomes following hyaluronic acid injection. In this study, the authors evaluated volumetric changes over 2 years and the maintenance potentials of both types of fillers on the anteromedial cheek using objective three-dimensional measurements. This comparative split-face study enrolled participants aged 30 to 50 years who received a midfacial injection of the test filler (Belotero Volume) on one side and a random control filler (Juvéderm, Restylane SubQ, or Yvoire Contour) on the contralateral side. The authors conducted three-dimensional scanning assessments at baseline and after 30 minutes; 3 days; 2, 4, 12, and 24 weeks; and 2 years. The volume augmentation effects for the anteromedial cheek of two monophasic fillers (Belotero Volume and Juvéderm Voluma) were maintained for at least 2 years (81 percent and 66 percent, respectively, compared to the volume at 4 weeks). Two biphasic fillers (Yvoire Contour and Restylane SubQ) maintained over 50 percent volume compared to the volume 4 weeks after injection. Monophasic fillers showed better outcomes than biphasic fillers; however, both types of hyaluronic acid fillers demonstrated superior efficacy, safety, and durability for volumetric augmentation in the anteromedial cheek. Objective data obtained using three-dimensional imaging analysis will enable dermatologists to better demonstrate the results of the procedure to patients, through the provision of visual aids.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Evaluation of Adverse Effects of Resorbable Hyaluronic Acid Fillers: Determination of Macrophage Responses

Resorbable tissue fillers for aesthetic purposes can induce severe complications including product migration, late swelling, and inflammatory reactions. The relation between product characteristics and adverse effects is not well understood. We hypothesized that the degree of cross-linking hyaluronic acid (HA) fillers was associated with the occurrence of adverse effects. Five experimental HA preparations similar to HA fillers were synthesized with an increasing degree of cross-linking. Furthermore, a series of commercial fillers (Perfectha^®) was obtained that differ in degradation time based on the size of their particulate HA components. Cytotoxic responses and cytokine production by human THP-1-derived macrophages exposed to extracts of the evaluated resorbable HA fillers were absent to minimal. Gene expression analysis of the HA-exposed macrophages revealed the responses related to cell cycle control and immune reactivity. Our results could not confirm the hypothesis that the level of cross-linking in our experimental HA fillers or the particulate size of commercial HA fillers is related to the induced biological responses. However, the evaluation of cytokine induction and gene expression in macrophages after biomaterial exposure presents promising opportunities for the development of methods to identify cellular processes that may be predictive for biomaterial-induced responses in patients.

A Comprehensive Review of Non-Energy-Based Treatments for Atrophic Acne Scarring

Scarring is a dire consequence of acne vulgaris. Particularly, atrophic acne scarring is highly prevalent among young adults, and its physical and psychological effects can persist throughout their lives if left untreated. This literature review will analyze various non-energy-based approaches to treating atrophic acne scarring, emphasizing recent advances within the last 5 to 10 years. To accomplish this, we performed a PubMed search for various acne scar treatments such as chemical peels, dermabrasion, microdermabrasion, subcision, microneedling, punch techniques, dermal fillers, and thread lifting. Our findings and analysis show that there is no panacean solution to treating atrophic acne scars, which explains the evolving trend towards developing unique combinatorial treatments. Although a fair comparison of each treatment approach is difficult to achieve due to the studies’ varying sample sizes, strength of evidence, treatment execution, etc, there still remains a level of consensus on what treatments are well suited for particular scar types.

Hyaluronic Acid Embolism Treated with Subcutaneous High and Low Hyaluronidase Doses: Efficacy and Surrounding Tissue Effect

BACKGROUND

The use of hyaluronidase in hyaluronic acid vascular occlusion has been evaluated; however, the models used do not accurately assimilate the facial morphologic characteristics or study the effects on adjacent tissues. The purpose of this study was to determine an effective concentration of subcutaneous hyaluronidase to dissolve a hyaluronic acid embolism and its effect on surrounding tissue.

METHODS

Fifteen rabbits were divided into six groups. An inguinal incision was performed on the femoral artery to create a hyaluronic acid embolism in the control and treatment groups (low-, medium-, and high-hyaluronidase groups). Hyaluronidase was injected subcutaneously. Photographic follow-up, histologic analysis, and quantification of hyaluronic acid were performed. Kruskal-Wallis test and post hoc with Bonferroni correction (p < 0.05) was used to compare the presence of hyaluronic acid in the arterial lumen between groups.

RESULTS

Despite the persistence of intravascular hyaluronic acid, macroscopic and microscopic differences were found between the embolism control group and embolism hyaluronidase high-dose group. Histologic analysis demonstrated thrombosis throughout groups. Skeletal muscle was least affected in the embolism hyaluronidase 500 IU group with less lysis and inflammatory infiltrate.

CONCLUSIONS

A 500 IU hyaluronidase dose partially prevents the damage caused by the embolism, and does not affect the surrounding tissue. The use of thrombolytic therapy combined with higher doses of hyaluronidase subcutaneously in this model is proposed.

Arterial Occlusion After Hyaluronic Acid Injection: Treatment With Hyaluronidase and Streptokinase

ABSTRACT

The most feared complication of the hyaluronic acid injections in the periorbital region is embolism of the central retinal artery. The present study aimed to compare the effectiveness of hyaluronidase administered intravenously (systemically) alone or in combination with streptokinase with that of intra-arterial revascularization. Thirty rats were divided into 5 groups. The bilateral oblique groin flap of the rats was raised; the right side was the experiment group, and the left side was the sham control. The right superficial epigastric artery was occluded with a hyaluronic acid injection. After occlusion, no additional procedures were performed in group 1, whereas group 2 received systemic hyaluronidase, group 3 received intra-arterial hyaluronidase, group 4 received systemic hyaluronidase and streptokinase, and group 5 received intra-arterial hyaluronidase and streptokinase. On the seventh day, the rats were killed, flap necrosis rate was calculated, and histological examination was performed. There was no significant difference in the necrosis rates of the rats in groups 2, 3, 4, and 5 (P > 0.05). In histological evaluation, the histological view closest to normal arterial structure was observed in group 4. Immunohistochemical analysis revealed that the ischemia scores of systemic therapy were significantly lower than those of intra-arterial therapy. These results have shown that hyaluronidase and streptokinase administered systemically is as effective as intra-arterial revascularization and does not cause arterial wall degeneration. It has been shown that systemic administration of hyaluronidase and streptokinase is as successful as intra-arterial revascularization in the treatment of arterial embolism with hyaluronic acid.

Toward Physicochemical and Rheological Characterization of Different Injectable Hyaluronic Acid Dermal Fillers Cross-Linked with Polyethylene Glycol Diglycidyl Ether

(1) Background: Injectable hyaluronic acid (HA) dermal fillers are used to restore volume, hydration and skin tone in aesthetic medicine. HA fillers differ from each other due to their cross-linking technologies, with the aim to increase mechanical and biological activities. One of the most recent and promising cross-linkers is polyethylene glycol diglycidyl ether (PEGDE), used by the company Matex Lab S.p.A., (Brindisi, Italy) to create the HA dermal filler PEGDE family. Over the last few years, several studies have been performed to investigate the biocompatibility and biodegradability of these formulations, but little information is available regarding their matrix structure, rheological and physicochemical properties related to their cross-linking technologies, the HA content or the degree of cross-linking. (2) Methods: Seven different injectable HA hydrogels were subjected to optical microscopic examination, cohesivity evaluation and rheological characterization in order to investigate their behavior. (3) Results: The analyzed cross-linked dermal fillers showed a fibrous "spiderweb-like" matrix structure, with each medical device presenting different and peculiar rheological features. Except for HA non cross-linked hydrogel 18 mg/mL, all showed an elastic and cohesive profile. (4) Conclusions: The comparative analysis with other literature works makes a preliminary characterization of these injectable medical devices possible.

Model-Based Prediction to Evaluate Residence Time of Hyaluronic Acid Based Dermal Fillers

Dermal fillers are gel-type substances for nonsurgical medical-device use to achieve facial rejuvenation. Currently, the most widely used skin fillers are hyaluronic-acid-based dermal fillers. This study aimed to explain the change in the volume of injected dermal fillers by developing a mathematical kinetic model for various dermal fillers. The kinetics of the injected fillers were separated by a biphasic phenomenon. We attributed an increase in filler volume to the hydration of hyaluronic acid molecules and injection-site reaction and a decrease in volume to enzyme-mediated degradation. To explain these in vivo characteristics of dermal fillers, we proposed a two-compartment model, divided into a depot compartment (where the filler was injected) and a subcutaneous compartment (an observation compartment where the fillers swell and degrade), assuming that the swelling and degradation occurred in accordance with the swelling and degradation rate constants, respectively. The model was developed using five hyaluronic-acid-based dermal fillers and NONMEM. We determined that the rate-limiting step for the complete degradation of the dermal fillers in vivo was the swelling phase, as described by the swelling rate constant (K_swell). This study could enable scientists developing novel dermal fillers to predict the in vivo behavior of fillers.

A comparison of the safety, efficacy, and longevity of two different hyaluronic acid fillers in filler rhinoplasty: A multicenter study

Filler rhinoplasty is a popular procedure in Asia, and it is of great importance to understand the clinical efficacy and durability of the different filler products that serve this purpose. Here, we aimed to evaluate and compare the safety, efficacy, and longevity of two different hyaluronic acid (HA) fillers in improving the nasal profile in Asians. A multicenter comparative trial was performed for 48 weeks after a single injection of a popular monophasic monodensified, and a newly developed biphasic HA filler. Assessments including patient satisfaction and three-dimensional (3D) imaging analysis were performed before, immediately after, 2 weeks, 12 weeks, 24 weeks, and 48 weeks after filler rhinoplasty. Twenty-eight Korean women underwent structured rhinoplasty were divided into monophasic monodensified (n = 14) and biphasic (n = 14) groups. There were significant changes in the facial profile following filler rhinoplasty throughout the study period. Overall, an increase of 1.75 mm in nose height, increase of 3.66° in the nasofrontal angle and 2.77° in the nasolabial angle, and radix elevation of 1.24 mm was noted at week 48 which was statistically different from the baseline values (P < .05). Between the different filler types, statistical difference was only noted in radix elevation (per milliliter of filler material) immediately after filler injection. No serious adverse event occurred during treatment or follow-up. Nonsurgical rhinoplasty with the specific HA filler products led to significant changes in the facial profile which persisted for 48 weeks. Overall, the clinical efficacy and safety were comparable between the two filler types except for radix elevation which was more prominent with C-C immediately after filler injection. J-V was superior to C-C in maintaining the radix elevation long term.

Ultrasound assessment of tissue integration of the crosslinked hyaluronic acid filler VYC-25L in facial lower-third aesthetic treatment: A prospective multicenter study

Background

Dermal fillers have become an integral part of any aesthetic physician's intervention.

Aims

To assess, by means of ultrasounds, the tissue integration of the hyaluronic acid (HA) dermal filler VYC‐25L in chin and jaw.

Methods

Prospective, noncomparative, open‐label, and multicenter study conducted on healthy subjects, with age comprised between 30 and 60 years old, who attended to the clinic to perform a facial rejuvenation treatment of the lower third of the face. VYC‐25L was injected using a 27G needle (supraperiosteal bolus, from 0.2 to 0.3 mL per bolus) in the chin and with canula (retrograde threads, from 0.4 to 0.6 mL) in the jaw. Ultrasound examinations (UE) were performed at each study center by the same experienced observer at baseline, immediately after injection, 48 hours, and 30 days after treatment.

Results

Thirty patients (10 per center) were included in the study. At baseline, UE found a characteristic heterogeneous pattern of subcutaneous cellular tissue, with alternation of soft anechoic and hyperechoic images. The UE, performed immediately after treatment, showed a poorly defined globular ultrasound pattern, with anechoic images indicative of liquid content. Forty‐eight hours after treatment, UE are still showing a globular pattern, with well‐defined anechoic areas. Thirty days after treatment, a thickening of the subcutaneous cellular tissue was observed in all the evaluated zones, with a total integration of the HA into the tissue.

Conclusion

VYC‐25L might represent a significant advance in volumization/restoration of the lower face. Its biointegration was total at day 30 and practically complete at 48 hours of treatment.

In Vitro Biocompatibility Evaluation of Nine Dermal Fillers on L929 Cell Line

Objective

Biomaterial research for soft tissue augmentation is an increasing topic in aesthetic medicine. Hyaluronic acid (HA) fillers are widely used for their low invasiveness and easy application to correct aesthetic defects or traumatic injuries. Some complications as acute or chronic inflammation can occur in patients following the injection. Biocompatibility assays are required for medical devices intended for human use, in order to prevent damages or injuries in the host. In this study, nine HA fillers were tested in order to evaluate their cytotoxicity and their effects on L929 cell line, according to the UNI EN ISO 10993 regulation.

Methods

Extracts were prepared from nine HA fillers, and MTS viability assay was performed after 24 h, 48 h, and 72 h of exposure of cells to extracts. Cells cultured with HA filler extracts were monitored for up to 72 h, counted, and stained with haematoxylin/eosin in order to evaluate the cell proliferation rate and morphology.

Results

None of the filler tested showed a cytotoxic effect. Two samples showed a higher vitality percentage and higher cell number while two samples showed a lower vitality percentage and lower cell number at 72 h.

Conclusion

Data obtained suggest that although examined fillers are not cytotoxic, they show different effects on the in vitro cell proliferation rate. In vitro studies of medical devices could lead to important implications since these could aid to predict effects about their in vivo application. These easy and rapid assays could be useful to test new materials intended for human use avoiding animal tests.

The Role of Hyaluronidase for the Skin Necrosis Caused by Hyaluronic Acid Injection-Induced Embolism: A Rabbit Auricular Model Study

BACKGROUND

Skin necrosis is considered the most serious complication of hyaluronic acid dermal filler injection procedures. To effectively treat skin necrosis, hyaluronidase injection is one of the essential preventative treatments, and yet optimal complication management remains an unmet need. Therefore, this paper investigates the effects of hyaluronidase injection timing on the treatment of skin necrosis.

METHODS

In an in vitro experiment, the carbazole method was used to determine the degradation time of hyaluronic acid gels in a large volume of hyaluronidase. In vivo experimental rabbit ear models were developed to simulate the skin necrosis caused by hyaluronic acid and the test animals distributed into five groups. Except one control group, the other four groups were injected with a large volume of hyaluronidase as treatment at 2 h, 4 h, 8 h and 16 h, respectively, after models were built. The necrosis degree of models was analyzed with necrotic area and histologic examination on the postoperative 7th day. Besides, temperatures of rabbit ears were observed to demonstrate the healing process of flap models.

RESULTS

The average necrotic area of flaps in the 2-h and 4-h injection groups showed a significant difference compared with that of the control group (p < 0.05; p < 0.05). The histologic examination showed that there were HA embolisms, vascular thrombolytic recanalization and arteriovenous thromboses in the survival area. In addition, the mean temperatures of the rabbit ear flaps fluctuated over time and showed clear differences between distal and proximal parts.

CONCLUSIONS

The area of flap necrosis positively correlates with injection timing of the large volume of hyaluronidase. More importantly, when injection timing is within 4 h, treatment effectiveness will be significantly improved.

NO LEVEL ASSIGNED

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 .

Treatments of Infra-Orbital Dark Circles by Various Etiologies

Dark circles refer to visible darkness of the infra-orbital areas. Dark circles are a cosmetic concern for many individuals, although not a medical concern. Moreover, clear definitions and possible causes of dark circles have not been elucidated. This study reviews the possible causes and treatment options for dark circles based on a review of the medical literature and the authors' clinical experience. Potential factors that contribute to dark circles include excessive pigmentation, shadowing due to tear troughs and infra-orbital fat herniation, shadowing due to infraorbital laxity and wrinkles, and thin, translucent skin overlying the orbicularis oculi muscle. Given the different possible causes for dark circles, therapeutic modalities must be individualized for each patient. Because various factors cause dark circles, it is useful to identify the underlying causes in order to select the appropriate treatment.

Ex vivo magnetic resonance imaging using hyaluronic acid fillers: Differences between monophasic and biphasic fillers

BACKGROUND/PURPOSE

Hyaluronic acid (HA) is an anionic, non-sulfated glycosaminoglycan distributed throughout the human skin and injectable HA fillers are the most commonly used in aesthetic field. This study aimed to determine if differences in physical characteristics of HA products (monophasic or biphasic fillers) affect the patterns of magnetic resonance imaging (MRI).

METHODS

Twenty biphasic fillers and nine monophasic fillers were obtained from a commercial source, and examined with a 3.0 Tesla MRI scanner. Visual assessments and measurements of signal intensity for region of interest (ROI) were performed. A non-parametric Wilcoxon rank sum test was used to compare the ROI values.

RESULTS

Visual assessments by a radiologist did not show significant differences between the two types of fillers. While the signal intensity between the two types of filler did not differ significantly for T1-weighted images, the signal intensity of the biphasic filler was lower than that of the monophasic filler for T2-weighted images (P<.01).

CONCLUSION

Monophasic and biphasic HA fillers exhibited different MRI properties. Our findings may provide better insights into the use of in vivo MRI to evaluate aesthetic, procedure-related complications.

Effect of molecular weight of hyaluronic acid (HA) on viscoelasticity and particle texturing feel of HA dermal biphasic fillers

Background

Hyaluronic acid (HA) dermal biphasic fillers are synthesized for their efficacy in correcting aesthetic defects such as wrinkles, scars and facial contouring defects. The fillers consist of crosslinked HA microspheres suspended in a noncrosslinked HA. To extend the duration of HAs within the dermis and obtain the particle texturing feel, HAs are crosslinked to obtain the suitable mechanical properties.

Results

Hyaluronic acid (HA) dermal biphasic fillers are prepared by mixing the crosslinked HA microspheres and the noncrosslinked HAs. The elastic modulus of the fillers increased with raising the volume fraction of the microspheres. The mechanical properties and the particle texturing feel of the fillers made from crosslinked HA (1058 kDa) microspheres suspended in noncrosslinked HA (1368 kDa) are successfully achieved, which are adequate for the fillers.

Conclusions

Dermal biphasic HA fillers made from 1058 kDa exhibit suitable elastic moduli (211 to 420 Pa) and particle texturing feel (scale 7 ~ 9).

The Myth of the "Biphasic" Hyaluronic Acid Filler

BACKGROUND

The terms "biphasic" and "monophasic" have been used frequently as a means of differentiating hyaluronic acid (HA) fillers. This type of categorization is based on misinterpretations of the term "phase" and provides no help to the practitioner when selecting the most appropriate product for each indication, patient, and injection technique.

OBJECTIVE

The purpose of this study was to analyze the properties of 2 HA filler families; Juvederm (JUV) (Allergan), often stated to be monophasic and Restylane (RES) (Galderma), often stated to be biphasic, and discuss what properties may have led to the use of the terms monophasic and biphasic.

MATERIALS AND METHODS

Three different methods were used for JUV and RES: determination of extractable HA; determination of water uptake; and microscopy.

RESULTS

The analyzed products were shown to contain both observable gel particles and extractable HA and have the ability to absorb added water.

CONCLUSION

The categorization of HA fillers as biphasic or monophasic was shown to be scientifically incorrect and should therefore be avoided. Further analytical measurement of the properties leading to this misinterpretation can provide information to discriminate and categorize HA fillers on a sounder scientific basis.

A Phase III, Randomized, Multi-Center, Double-Masked, Matched-Pairs, Active-Controlled Trial to Compare the Efficacy and Safety between Neuramis Deep and Restylane in the Correction of Nasolabial Folds

BACKGROUND

We conducted this clinical study to compare the efficacy and safety between Neuramis Deep and Restylane in the correction of nasolabial folds.

METHODS

In this phase III, randomized, multi-center, double-masked, matched-pairs, active-controlled trial (ClinicalTrials.gov Identifier: NCT01585220), we evaluated a total of 67 subjects (n=67). All the subjects underwent Neuramis Deep treatment on one side and Restylane on the contralateral side of the bilateral nasolabial folds at a ratio of 1:1. To compare the efficacy of Neuramis Deep and Restylane, we evaluated the Wrinkle Severity Rating Scale scores and those of the Global Aesthetic Improvement Scale. In addition, we compared the safety of Neuramis Deep and Restylane based on adverse events, physical examination, and clinical laboratory tests.

RESULTS

Neuramis Deep was not inferior in improving the nasolabial folds as compared with Restylane. In addition, there was no significant difference in the efficacy between Neuramis Deep and Restylane. There were no significant differences in safety parameters between Neuramis Deep and Restylane.

CONCLUSIONS

In conclusion, our results indicate that Neuramis Deep may be a safe, effective material for improving the nasolabial folds. However, further studies are warranted to compare the tolerability of Neuramis Deep and Restylane based on histopathologic findings.

The Surgical Lips Deformity Corrected with Hyaluronic Fillers: A Case Report

BACKGROUND:

Hyaluronic filler is a sterile, biodegradable, viscoelastic, isotonic, transparent injectable gel implant which was approved by Food and Drug Administration (FDA) 1996. It is used for face reconstruction and modelling.

CASE PRESENTATION:

We report the case of a 40-year-old Serbian woman who presented after surgery of cleft lip, primary and secondary palate. We performed a biphasic therapy; in the first stage in the zone semimucosis lips is initially carried incision scar tissue. The second stage is placed hyaluronan implant.

CONCLUSION:

This case illustrates that, although hyaluronic fillers used mainly for correction of healthy tissue can be successfully used in the treatment of postoperative scars.

New-generation filler based on cross-linked carboxymethylcellulose: study of 350 patients with 3-year follow-up

Purpose

In recent years there has been a growing interest in nonsurgical procedures for facial rejuvenation. Hyaluronic acid is currently the most widely used dermal filler for the treatment of facial wrinkles. However, new products with interesting features are being introduced into the market. Cross-linked carboxymethylcellulose is one of these and represents a new alternative for the correction of wrinkles and facial defects.

Patients and methods

The retrospective, multicenter, open-label study on nasolabial folds reported here was carried out between January 2010 and April 2014 on 350 subjects between 22 and 67 years of age for a 36-month follow-up period in order to consistently and extensively assess the safety and performance of this treatment.

Results

The study revealed effective and durable correction of nasolabial wrinkles for periods of 9–12 months. Product reapplication over a 36-month period did not lead to an increase in adverse effects, which always remained rare and of little clinical significance, usually consisting of bruising and redness.

Conclusion

Cross-linked carboxymethyl cellulose has been shown to be a safe and effective alternative to the resorbable products currently on the market.