HA-based dermal filler: downstream process comparison, impurity quantitation by validated HPLC-MS analysis, and in vivo residence time study

Safety and efficacy of hyaluronic acid injectable filler in the treatment of nasolabial fold wrinkle: a randomized, double-blind, self-controlled clinical trial

INTRODUCTION

The injectable skin fillers available for soft tissue augmentation are constantly growing, providing esthetic surgeons with more options in the treatment of scars, lines, and wrinkles. Hyaluronic acid (HA)-derived injectable fillers are ideal to reduce the appearance of nasolabial folding. This study investigated the efficacy and safety of the commercially available HA filler from Maxigen Biotech Inc. (MBI-FD) in the treatment of nasolabial folds (NLFs).

METHODS

We analyzed 1,4-butanediol diglycidyl ether (BDDE) residues and injection force test and observed the protein content in MBI-FD, and then was cultured in fibroblast L929 cells and examined for cytotoxicity. Finally, 95 healthy participants underwent dermal filler injection therapy to evaluate the efficacy and safety for 24 and 52 weeks, respectively.

RESULTS

BDDE residues in MBI-FD was <0.125 µg/mL. MBI-FD was fitted using 27- and 30-G injection needles with an average pushing force of 14.30 ± 2.07 and 36.43 ± 3.11 N, respectively. Sodium hyaluronate protein in MBI-FD was 7.19 µg/g. The cell viabilities of 1× and 0.5× MBI-FD were 83.25% ± 3.58% and 82.23% ± 1.85%, respectively, indicating MBI-FD had no cytotoxicity, and decreased NLF wrinkles with no serious adverse events.

CONCLUSION

MBI-FD is an effective filler for tissue augmentation of the NLFs and may be a suitable candidate as an injectable dermal filler for tissue augmentation in humans in the future.

Strengthening the Key Features of Volumizing Fillers: Projection Capacity and Long-Term Persistence

Volumizing fillers aim to create or restore facial volume in fat layers. To provide strong tissue lifting and long-term persistence, gels are generally designed with stiff properties, characterized by a high storage modulus (G'). However, clinical evidence shows a discrepancy between high G' and good lifting capacities, especially after skin tension has been exerted on the gel. To better explore the in vivo behavior of a gel, we first evaluated the elastic moduli of five commercial volumizers (RHA4, JUVVOL, RESVOL, RESLYFT, and BELVOL) in dynamic compression mode, E'. We further developed a Projection Index score based on the rheological assessment of creep in compression to mimic skin tension-induced stress relaxation (flattening). Finally, the ability of a gel to resist enzymatic degradation was analyzed with a multidose approach. Despite similar clinical indications, volumizers exhibited distinct behaviors. RHA4 and BELVOL showed the highest E' values (resistance to strain), RHA4, JUVVOL, and RESVOL exhibited the greatest projection capacities, while JUVVOL and RHA4 offered the largest persistence to enzymatic degradation. In this article, we introduce the use of the Projection Index to efficiently assess the ability of a gel to lift tissues, thus increasing preclinical models' efficiency and reducing the need for animal studies.

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.

Advances in Hyaluronic Acid for Biomedical Applications

Hyaluronic acid (HA) is a large non-sulfated glycosaminoglycan that is the main component of the extracellular matrix (ECM). Because of its strong and diversified functions applied in broad fields, HA has been widely studied and reported previously. The molecular properties of HA and its derivatives, including a wide range of molecular weights but distinct effects on cells, moisture retention and anti-aging, and CD44 targeting, promised its role as a popular participant in tissue engineering, wound healing, cancer treatment, ophthalmology, and cosmetics. In recent years, HA and its derivatives have played an increasingly important role in the aforementioned biomedical fields in the formulation of coatings, nanoparticles, and hydrogels. This article highlights recent efforts in converting HA to smart formulation, such as multifunctional coatings, targeted nanoparticles, or injectable hydrogels, which are used in advanced biomedical application.

Hyaluronan Hydrogels: Rheology and Stability in Relation to the Type/Level of Biopolymer Chemical Modification

BDDE (1,4-butanediol-diglycidylether)-crosslinked hyaluronan (HA) hydrogels are widely used for dermo-aesthetic purposes. The rheology and stability of the gels under physiological conditions greatly affect their clinical indications and outcomes. To date, no studies investigating how these features are related to the chemistry of the polymeric network have been reported. Here, four available HA-BDDE hydrogels were studied to determine how and to what extent their rheology and stability with respect to enzymatic hydrolysis relate to the type and degree of HA structural modification. ¹H-/¹³C-NMR analyses were associated for the quantification of the “true” HA chemical derivatization level, discriminating between HA that was effectively crosslinked by BDDE, and branched HA with BDDE that was anchored on one side. The rheology was measured conventionally and during hydration in a physiological medium. Sensitivity to bovine testicular hyaluronidase was quantified. The correlation between NMR data and gel rheology/stability was evaluated. The study indicated that (1) the gels greatly differed in the amounts of branched, crosslinked, and overall modified HA, with most of the HA being branched; (2) unexpectedly, the conventionally measured rheological properties did not correlate with the chemical data; (3) the gels’ ranking in terms of rheology was greatly affected by hydration; (4) the rheology of the hydrated gels was quantitatively correlated with the amount of crosslinked HA, whereas the correlations with the total HA modification level and with the degree of branched HA were less significant; (5) increasing HA derivatization/crosslinking over 9/3 mol% did not enhance the stability with respect to hyaluronidases. These results broaden our knowledge of these gels and provide valuable information for improving their design and characterization.

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.

Evaluation of the Rheologic and Physicochemical Properties of a Novel Hyaluronic Acid Filler Range with eXcellent Three-Dimensional Reticulation (XTR™) Technology

Soft-tissue fillers made of hyaluronic acid and combined with lidocaine have recently become a popular tool in aesthetic medicine. Several manufacturers have developed their own proprietary formulae with varying manufacturing tools, concentrations, crosslinked three-dimensional network structures, pore size distributions of the fibrous networks, as well as cohesivity levels and rheological properties, lending fillers and filler ranges their unique properties and degradability profiles. One such range of hyaluronic acid fillers manufactured using the novel eXcellent three-dimensional reticulation (XTR™) technology was evaluated in comparison with other HA fillers and filler ranges by an independent research laboratory. Fillers manufactured with the XTR™ technology were shown to have characteristic rheological, crosslinking and biophysical factors that support the suitability of this filler range for certain patient profiles.