Performance assessment of an injectable hyaluronic acid/polylactic acid complex hydrogel with enhanced biological properties as a dermal filler

Injectable hyaluronic acid (HA) hydrogel plays an important role in dermal filling. However, conventional HA dermal fillers mostly lack bio-functional diversity and frequently cause adverse reactions because of the chemical stiffness of highly modified degree and crosslinker residues. In this study, polylactic acid (PLA) was embedded into HA hydrogel as a bioactive substance and 1,4-butanediol diglycidyl ether was used as a crosslinker to prepare the HA/PLA composite hydrogel with enhanced biocompatibility and biological performance. We aimed to investigate the properties of HA/PLA composite hydrogels as dermal fillers by assessing the rheological properties, surface microstructure, enzymolysis stability, swelling ratio, degradation rate, cytotoxicity, and anti-wrinkle effect on photo-aged skin. The results showed that the stability and stiffness of the composite hydrogel decreased with an increasing amount of PLA, while the in vivo safety of the HA/PLA hydrogel was enhanced, showing no adverse reactions such as edema, redness, or swelling. Moreover, the composite hydrogel with 2 wt% PLA exhibited excellent anti-wrinkle effects, showing the highest collagen production. Thus, the PLA-embedded HA composite hydrogel showed potential as a dermal filler with high safety, easy injectability, and excellent anti-wrinkle effects.

Understanding Public Awareness and Practices of Nonsurgical Facial Dermal Fillers: A Cross-Sectional Study in Saudi Arabia

BACKGROUND

Dermal fillers augment soft tissues by replacing lost volume in the skin or subcutaneous fat. Dentists and other professionals utilize or recommend facial fillers for cosmetic and therapeutic purposes.

AIMS

This study aims to investigate public awareness regarding using nonsurgical facial dermal fillers in Saudi Arabia.

METHODS AND MATERIAL

A cross-sectional study was conducted using an online self-administered questionnaire distributed to a total of 400 males and females through social media platforms. The participants reside in Mecca, Saudi Arabia. Descriptive statistics and the Chi-square test were employed for data analysis.

RESULTS

A total of 256 participants completed the survey, including 204 females and 51 males, with a mean age of 33.86 (SD = 10.5) years. Among the participants, 88 (34.4%) reported using facial fillers. Among them, only 46 (18%) were frequent consumers. Knowledge regarding correctly using facial fillers was generally high, especially for the lips (240, 94%), chin augmentation (203, 79.3%), and face lifting (226, 88.3%). However, participants' knowledge needed improvement in other areas. Most participants were aware of the side effects, except for visual impairment (83, 32.4%) and blockage of the vessels (128, 50%).

CONCLUSIONS

The findings highlighted a remarkable level of knowledge among participants regarding the uses of fillers. However, participants demonstrated low awareness of all possible side effects associated with the treatment. Participants had valid reasons for undergoing facial treatments. However, constraints preventing them from pursuing fillers included fear of unexpected results and financial limitations.

Collagen type II-hyaluronan interactions - the effect of proline hydroxylation: a molecular dynamics study

Hyaluronan-collagen composites have been employed in numerous biomedical applications. Understanding the interactions between hyaluronan and collagen is particularly important in the context of joint cartilage function and the treatment of joint diseases. Many factors affect the affinity of collagen for hyaluronan. One of the important factors is the ratio of 3- or 4-hydroxy proline to proline residues. This article presents the results from molecular dynamics calculations of HA-collagen type II interactions with hyaluronan. The applied protocol employed docking and geometry optimization of complexes built using collagen structures with different numbers of hydroxyl groups attached to proline moieties. It was established that the hydroxyproline/proline ratio affects both structural and energetic features of the collagen-hyaluronan complex. Proline hydroxylation was found to significantly influence the number of all identified types of molecular forces, hydrophobic interactions, water bridges and hydrogen bonds, which can be formed between collagen and hyaluronan. Importantly, an increase in the hydroxyproline/proline ratio in the collagen chain increases the binding affinity for hyaluronan. This is illustrated by the linear correlation between the binding free energy and the hydroxylation degree. A comparison of the results obtained for 3 and 4 hydroxylation of proline indicates that the hydroxyl group attachment position plays a minor role in complex stabilization. However, a slightly stronger affinity was observed for 4 hydroxylation. In order to evaluate the effect of the aqueous environment on the collagen-hyaluronan complex stability, the enthalpic and entropic contributions to the free energy of solvation were analyzed.

Ultrasound Responsive Smart Implantable Hydrogels for Targeted Delivery of Drugs: Reviewing Current Practices

Over the last two decades, the process of delivering therapeutic drugs to a patient with a controlled release profile has been a significant focus of drug delivery research. Scientists have given tremendous attention to ultrasound-responsive hydrogels for several decades. These smart nanosystems are more applicable than other stimuli-responsive drug delivery vehicles (ie UV-, pH- and thermal-, responsive materials) because they enable more efficient targeted treatment via relatively non-invasive means. Ultrasound (US) is capable of safely transporting energy through opaque and complex media with minimal loss of energy. It is capable of being localized to smaller regions and coupled to systems operating at various time scales. However, the properties enabling the US to propagate effectively in materials also make it very difficult to transform acoustic energy into other forms that may be used. Recent research from a variety of domains has attempted to deal with this issue, proving that ultrasonic effects can be used to control chemical and physical systems with remarkable specificity. By obviating the need for multiple intravenous injections, implantable US responsive hydrogel systems can enhance the quality of life for patients who undergo treatment with a varied dosage regimen. Ideally, the ease of self-dosing in these systems would lead to increased patient compliance with a particular therapy as well. However, excessive literature has been reported based on implanted US responsive hydrogel in various fields, but there is no comprehensive review article showing the strategies to control drug delivery profile. So, this review was aimed at discussing the current strategies for controlling and targeting drug delivery profiles using implantable hydrogel systems.

Crosslinking Hyaluronic Acid Soft-Tissue Fillers: Current Status and Perspectives from an Industrial Point of View

INTRODUCTION

Hyaluronan (HA)-based soft-tissue fillers are injectable crosslinked hydrogels aimed to counteract facial skin aging signs via minimally invasive procedures. The crosslinking step is required to drastically improve HA residence time in vivo and provide the gel with specific viscoelastic properties matching the clinical indications. While HA as a raw material and HA fillers are widely studied, little is reported about crosslinkers themselves used in commercial fillers.

AREAS COVERED

This article introduces the specifications of the ideal crosslinker in HA fillers. The properties of commercially used crosslinkers are reviewed. An up-to-date review of innovative hydrogel fabrication alternatives is conducted, and advantages and drawbacks are discussed.

EXPERT OPINION

HA fillers are predominantly manufactured using 1,4-butanediol diglycidyl ether (BDDE) which is considered as the gold standard crosslinker worldwide due to its proven and unrivalled clinical track record of more than 20 years. Extensive studies have been published covering BDDE-crosslinked HA fillers' chemistry, gel properties, and clinical effectiveness and safety. However, new hydrogel fabrication strategies have emerged, paving the way for innovative alternatives potentially bringing novel features to HA fillers. Nevertheless, major efforts must still be implemented to assess their safety, efficacy, stability and suitability for industrialization.

The Potential Use of Novel Plant-Derived Recombinant Human Collagen in Aesthetic Medicine

SUMMARY

Recombinant human type I collagen, identical in structure and functionality to human type I collagen, was successfully expressed and extracted from genetically modified tobacco plants. Contrarily to tissue extracted protein, rhCollagen is not immunogenic and not allergenic and has an intact triple helix structure showing superior biological functionality. A photocurable rhCollagen was developed by chemically modifying the protein to allow cross-linking under illumination at various wavelengths, maintaining the protein structural and biological functions. The use of the photocurable rhCollagen in aesthetic medicine, especially as a dermal filler and as a bioink for 3D-printed breast implant is discussed in this article.

Investigation of an injectable gold nanoparticle extracellular matrix

Post-traumatic osteoarthritis (PTOA) is a progressive articular degenerative disease that degrades articular cartilage and stimulates apoptosis in chondrocyte cells. An injectable decellularized, extracellular matrix (ECM) scaffold, that might be able to combat the effects of PTOA, was developed where the ECM was conjugated with 20 nm gold nanoparticles (AuNP) and supplemented with curcumin and hyaluronic acid (HA). Porcine diaphragm ECM was decellularized and homogenized; AuNPs were conjugated using chemical crosslinking followed by mixing with curcumin and/or HA. Injection force testing and scanning electron microscopy with energy-dispersive X-ray spectroscopy were utilized to characterize the ECM scaffolds. In vitro testing with L929 murine fibroblasts, equine synovial fibroblasts, and Human Chondrocytes were used to determine biocompatibility, reactive oxygen species (ROS) reduction, and chondroprotective ability. The results demonstrated that conjugation of 20 nm AuNPs to the ECM was successful without significantly altering the physical properties as noted in the low injection force. In vitro work provided evidence of biocompatibility with a propensity to reduce intracellular ROS and an ability to mitigate apoptosis of chondrocyte cells stimulated with IL-1β, a known apoptosis inducing cytokine. It was concluded that an injectable AuNP-ECM may have the ability to mitigate inflammation and apoptosis.

Objective evaluation of biomaterial effects after injection laryngoplasty - Introduction of artificial intelligence-based ultrasonic image analysis

OBJECTIVE

Hyaluronic acid (HA) can be degraded over time. However, persistence of the effects after injection laryngoplasty (IL) for unilateral vocal fold paralysis (UVFP), longer than expected from HA longevity, has been observed. The purpose of the study was to develop a methodology with clinical utility for objective evaluation of the temporal change in HA volume after IL using artificial intelligence (AI)-based ultrasonic assessment.

DESIGN, SETTING AND PARTICIPANTS

Imaging phantoms simulating injected HA were built in different volumes for designing the algorithm for machine learning. Subsequently, five adult patients who had undergone IL with HA for UVFP were recruited for clinical evaluation.

MAIN OUTCOME MEASURES

Estimated volumes were evaluated for injected HA by the automatic algorithm as well as voice outcomes at 2 weeks, and 2 and 6 months after IL.

RESULTS

On imaging phantoms, contours on each frame were described well by the algorithm and the volume could be estimated accordingly. The error rates were 0%-9.2%. Moreover, the resultant contours of the HA area were captured in detail for all participants. The estimated volume decreased to an average of 65.76% remaining at 2 months and to a minimal amount at 6 months while glottal closure remained improved.

CONCLUSION

The volume change of the injected HA over time for an individual was estimated non-invasively by AI-based ultrasonic image analysis. The prolonged effect after treatment, longer than HA longevity, was demonstrated objectively for the first time. The information is beneficial to achieve optimal cost-effectiveness of IL and improve the life quality of the patients.

Injectable Hydrogels: From Laboratory to Industrialization

The transfer of some innovative technologies from the laboratory to industrial scale is many times not taken into account in the design and development of some functional materials such as hydrogels to be applied in the biomedical field. There is a lack of knowledge in the scientific field where many aspects of scaling to an industrial process are ignored, and products cannot reach the market. Injectable hydrogels are a good example that we have used in our research to show the different steps needed to follow to get a product in the market based on them. From synthesis and process validation to characterization techniques used and assays performed to ensure the safety and efficacy of the product, following regulation, several well-defined protocols must be adopted. Therefore, this paper summarized all these aspects due to the lack of knowledge that exists about the industrialization of injectable products with the great importance that it entails, and it is intended to serve as a guide on this area to non-initiated scientists. More concretely, in this work, the characteristics and requirements for the development of injectable hydrogels from the laboratory to industrial scale is presented in terms of (i) synthesis techniques employed to obtain injectable hydrogels with tunable desired properties, (ii) the most common characterization techniques to characterize hydrogels, and (iii) the necessary safety and efficacy assays and protocols to industrialize and commercialize injectable hydrogels from the regulatory point of view. Finally, this review also mentioned and explained a real example of the development of a natural hyaluronic acid hydrogel that reached the market as an injectable product.

Polyhedral Oligomeric Silsesquioxane /Platelets Rich Plasma/Gelrite-Based Hydrogel Scaffold for Bone Tissue Engineering

BACKGROUND

Polyhedral oligomeric silsesquioxane (POSS) is a monomer with silicon structure and an internal nanometric cage.

OBJECTIVE

The purpose of this study was to provide an injectable hydrogel that could be easily located in open or closed bone fractures and injuries, and also to reduce the possible risks of infections caused by bone graft either as an allograft or an autograft.

METHODS

Various formulations of temperature sensitive hydrogels containing hydroxyapatite, Gelrite, POSS and platelets rich plasma (PRP), such as the co-gelling agent and cell growth enhancer, were prepared. The hydrogels were characterized for their injectability, gelation time, phase transition temperature and viscosity. Other physical properties of the optimized formulation including compressive stress, compressive strain and Young's modulus as mechanical properties, as well as storage and loss modulus, swelling ratio, biodegradation behavior and cell toxicity as rheometrical parameters were studied on human osteoblast MG-63 cells. Alizarin red tests were conducted to study the qualitative and quantitative osteogenic capability of the designed scaffold, and the cell adhesion to the scaffold was visualized by scanning electron microscopy.

RESULTS

The results demonstrated that the hydrogel scaffold mechanical force and injectability were 3.34±0.44 Mpa and 12.57 N, respectively. Moreover, the scaffold showed higher calcium granules production in alizarin red staining compared to the control group. The proliferation of the cells in G4.5H1P0.03PRP10 formulation was significantly higher than in other formulations (p<0.05).

CONCLUSION

The optimized Gelrite/Hydroxyapatite/POSS/PRP hydrogel scaffold has useful impacts on osteoblasts activity, and may be beneficial for local drug delivery in complications including a break or bone loss.

Hyaluronic acid containing scaffolds ameliorate stem cell function for tissue repair and regeneration

Recent evidence based studies have proposed hyaluronic acid (HA) as an emerging biopolymer for various tissue engineering application. Meanwhile, stem cells (SCs) have also gained immense popularity for their tissue regenerative capacity. Thus, combining HA and stem cells for tissue engineering application have shown to foster tissue repair and regeneration process. HA possesses the ability to interact with SCs via cellular surface receptors along with the capacity to elicit the process of differentiation. The influence of HA on stem cells has been widely investigated in cartilage and bone repair but their properties of reducing inflammation has also been explored in various other tissue repair processes. In this review, we have provided an insight to the effect of crosslinked and non-crosslinked HA on various stem cells. Further, HA based scaffolds combined with stem cells have shown to have a synergistic effect in the regeneration capacity. Also, various chemically modified HA and biomolecules conjugated HA as a suitable carrier or matrix for stem cells delivery and the effect of HA in fine tuning the stem cells function is discussed.

Hyaluronic Acid as a Component of Natural Polymer Blends for Biomedical Applications: A Review

In this review, we provide a report on recent studies in the field of research on the blends of hyaluronic acid with other natural polymers, namely collagen and chitosan. Hyaluronic acid has attracted significant interest in biomedical and cosmetic applications due to its interesting properties. In recent years, blends of hyaluronic acid with other polymers have been studied for new materials development. New materials may show improved properties that are important in the biomedical applications and in cosmetic preparations. In this review paper, the structure, preparation, and properties of hyaluronic acid blends with collagen and chitosan have been discussed and examples of new materials based on such blends have been presented. A comparison of the currently available information in the field has been shown. Future aspects in the field of hyaluronic acid blends and their applications in the biomedical and cosmetic industry have also been mentioned.

Proteins and Peptides as Important Modifiers of the Polymer Scaffolds for Tissue Engineering Applications-A Review

Polymer scaffolds constitute a very interesting strategy for tissue engineering. Even though they are generally non-toxic, in some cases, they may not provide suitable support for cell adhesion, proliferation, and differentiation, which decelerates tissue regeneration. To improve biological properties, scaffolds are frequently enriched with bioactive molecules, inter alia extracellular matrix proteins, adhesive peptides, growth factors, hormones, and cytokines. Although there are many papers describing synthesis and properties of polymer scaffolds enriched with proteins or peptides, few reviews comprehensively summarize these bioactive molecules. Thus, this review presents the current knowledge about the most important proteins and peptides used for modification of polymer scaffolds for tissue engineering. This paper also describes the influence of addition of proteins and peptides on physicochemical, mechanical, and biological properties of polymer scaffolds. Moreover, this article sums up the major applications of some biodegradable natural and synthetic polymer scaffolds modified with proteins and peptides, which have been developed within the past five years.

Extracellular matrix-mimetic composite hydrogels of cross-linked hyaluronan and fibrillar collagen with tunable properties and ultrastructure

A platform of enzymatically-crosslinked Collagen/Tyramine hyaluronan derivative (Col/HA-Tyr) hydrogels with tunable compositions and gelation conditions was developed to evaluate the impact of the preparation conditions on their physical, chemical and biological properties. At low HA-Tyr content, hydrogels exhibited a fibrillar structure, with lower mechanical properties compared to pure Col hydrogels. At high HA-Tyr and Horse Radish Peroxydase (HRP) content, a microfibrillar network was formed beside the banded Col fibrils and a synergistic effect of the hybrid structure on mechanical properties was observed. These hydrogels were highly resistant against enzymatic degradation while keeping a high degree of hydration. Unlike HA-Tyr hydrogels, encapsulation of human dermal fibroblasts within Col/HA-Tyr hydrogels allowed for high cell viability. These results showed that high HA-Tyr and HRP concentrations are required to positively impact the physical properties of hydrogels while preserving collagen fibrils. Those Col/HA-Tyr hydrogels appear promising for novel tissue engineering applications following a biomimetic approach.

Hyaluronic Acid-Based Hybrid Hydrogel Microspheres with Enhanced Structural Stability and High Injectability

For hydrogel injection applications, it is important to improve the strength and biostability of the hydrogel as well as its injectability to pass easily through the needle. Making gel microspheres is one approach to achieve these improvements. Granulization of a bulk hydrogel is a common procedure used to form microsized particles; however, the nonuniform size and shape cause an uneven force during injection, damaging the surrounding tissue and causing pain to the patients. In this study, injectable hyaluronic acid (HA)-based hybrid hydrogel microspheres were fabricated using a water-in-oil emulsion process. The injectability was significantly enhanced because of the relatively uniform size and spherical shape of the hydrogel formulates. In addition, the biostability and mechanical strength were also increased owing to the increased cross-linking density compared with that of conventionally fabricated gel microparticles. This tendency was further improved after in situ calcium phosphate precipitation. Our findings demonstrate the great potential of HA-based hydrogel microspheres for various clinical demands requiring injectable biomaterials.

Dual-plane hyaluronic acid treatment for atrophic acne scars

BACKGROUND

Acne is a common condition that affects up to 80% of all adolescents. Scarring may affect some 95% as a function of severity and delay before treatment. The pathogenesis includes enzymatic degradation of collagen fibers and subcutaneous fat.

OBJECTIVE

This study aimed to treat atrophic acne scars using the Dual-Plane injection of Hyaluronic Acid.

METHODS

A total of 12 patients with moderate-to-severe atrophic acne scars were treated with a novel NAHYCO™ based Hyaluronic Acid filler, using a dual-plane technique for two treatment sessions at a 4-week interval. Results were objectively assessed by two blinded Dermatologists and subjectively evaluated by the patients themselves.

RESULTS

A total of 8 out of the 12 patients reported moderate improvement, two indicated marked improvement and two rated minimal improvement. Dermatologists' mean global evaluation score was 2.5 ± 0.43.

LIMITATIONS

The small sample size and regional nature of a single-center study. Nevertheless, both the expert dermatologists' and the patients' evaluations of standardized high-resolution medical photographs were consistent, suggesting that this inherent bias was negligible.

CONCLUSION

The treatment led to impressive improvement in the depth of the scars, suggesting that this technique can result in safe and rapid amelioration of atrophic acne scars in only two sessions.

Controlling methacryloyl substitution of chondroitin sulfate: injectable hydrogels with tunable long-term drug release profiles

Drug delivery systems capable of local sustained release of small molecule therapeutics remain a critical need in many fields, including oncology. Here, a system to create tunable hydrogels capable of modulating the loading and release of cationic small molecule therapeutics was developed. Chondroitin sulfate (CS) is a sulfated glycosaminoglycan that has many promising properties, including biocompatibility, biodegradation and chemically modifiable groups for both covalent and non-covalent bonding. CS was covalently modified with photocrosslinkable methacryloyl groups (CSMA) to develop an injectable hydrogel fabrication. Utilizing anionic groups, cationic drugs can be adsorbed and released from the hydrogels. This study demonstrates the synthesis of CSMA with a varying degree of substitution (DS) to generate hydrogels with varying swelling properties, maximum injection force, and drug release kinetics. The DS of the synthesized CSMA ranged from 0.05 ± 0.02 (2 h reaction) to 0.28 ± 0.02 (24 h reaction) with a DS of 1 representing 100% modification. The altered DS resulted in changes in hydrogel properties with the swelling of 20% CSMA hydrogels ranging from 42 (2 h reaction) to 13 (24 h reaction) and injection forces ranging from 18 N (2 h reaction) to 94 N (24 h reaction). The release of sunitinib, an oncology therapeutic that inhibits intracellular signaling by targeting multiple receptor tyrosine kinases, ranged from 18 μg per day (2 h reaction) to 9 μg per day (24 h reaction). While decreasing the DS increased the hydrogel swelling and rate of therapeutic release, it also limited the hydrogel fabrication range to only those containing 10% or higher CSMA. Blended polymer systems with poly(vinyl alcohol)-methacrylate (PVAMA) were fabricated to stabilize the resulting hydrogels via attenuating the swelling properties. Release profiles previously unattainable with the pure CSMA hydrogels were achieved with the blended hydrogel formulations. Overall, these studies identify a method to formulate tunable CSMA and blended CSMA/PVAMA hydrogels capable of sustained release of cationic therapeutics over six weeks with applications in oncology therapeutics.

Effect of Titanium Implants Coated with Radiation-Crosslinked Collagen on Stability and Osseointegration in Rat Tibia

This study aimed to evaluate the titanium (Ti) implants coated with collagen type Ⅰ crosslinked using gamma-irrigation or glutaraldehyde (GA). The in vitro surface observations, quantification assay, and cell studies using human mesenchymal stem cells (hMSCs) were conducted. For in vivo experiments, the implants were divided into three groups and inserted into the rat tibias: control group (non-treated Ti implant), GA group (Ti implants coated with GA-crosslinked collagen) and 25 kGy group (Ti implants coated with gamma-radiation-crosslinked collagen at dose of 25 kGy). The animals were sacrificed at 4 weeks after implantation and the tissue sections were obtained. New bone volume (mm³) and bone-to-implant contact (BIC, %) within the region of interest (ROI) was measured. The in vitro results showed the highest osteogenic differentiation and levels of osteogenesis-related gene expressions in the 25 kGy group without cytotoxicity. The new bone volume of GA group was significantly higher than the control (p < 0.05). In the result of the BIC, the 25 kGy group was significantly higher than the control (p < 0.05). However, there was no significant difference between the experimental groups. Within the limitations of this study, Ti implant coated with gamma-radiation-crosslinked collagen has potential utility without side effects from chemical agents.

An injectable and physical levan-based hydrogel as a dermal filler for soft tissue augmentation

A novel levan-based injectable hydrogel was developed as a dermal filler having better in vivo stability and efficacy compared to HA-based hydrogel.

Autologous Adipose-Derived Tissue Matrix Part II: Implantation Biology

BACKGROUND

In part 1 of this study it was shown that liposuctioned fat could be a sufficient source of autologous collagen for use as a filler or in reconstruction. The collagen composition in liposuctioned fat was shown to form a cross-linked helical matrix composed of types II, III, and IV. Additionally, viable adipocytes and fibroblasts among other cells were found.

OBJECTIVES

The purpose of this research was to study the biology of this matrix after subsequent implantation compared to Juvederm (Allergan, Parsippany, NJ) common soft tissue filler.

METHODS

Fat was obtained from individuals undergoing routine liposuction and was processed by a two-step process to obtain a connective tissue matrix. The matrix was then cryo-frozen for a minimum of 4 weeks after which it was thawed and implanted in 46 nude mice. Juvederm Ultra was used as the control article and the animals followed for one year.

RESULTS

Liposuctioned fat was obtained from 10 individuals and processed as previously described. Mice were harvested at 3, 6, 9, and 12 months and histology obtained. There were no adverse effects from either article and the bio-reactivity rating was 0. The implanted collagen compared favorably to Juvederm at all stages and was found to be replaced by new collagen and fat.

CONCLUSIONS

A collagen matrix with viable cells for autologous use can be obtained from liposuctioned fat which has been processed and cryo-frozen. The material lasts at least one year and is slowly replaced by new collagenand fat.

LEVEL OF EVIDENCE

5.

Autologous Adipose-Derived Tissue Matrix Part I: Biologic Characteristics

BACKGROUND

Autologous collagen is an ideal soft tissue filler and may serve as a matrix for stem cell implantation and growth. Procurement of autologous collagen has been limited, though, secondary to a sufficient source. Liposuction is a widely performed and could be a source of autologous collagen.

OBJECTIVES

The amount of collagen and its composition in liposuctioned fat remains unknown. The purpose of this research was to characterize an adipose-derived tissue-based product created using ultrasonic cavitation and cryo-grinding. This study evaluated the cellular and protein composition of the final product.

METHODS

Fat was obtained from individuals undergoing routine liposuction and was processed by a 2 step process to obtain only the connective tissue. The tissue was then evaluated by scanning electronic microscope, Western blot analysis, and flow cytometry.

RESULTS

Liposuctioned fat was obtained from 10 individuals with an average of 298 mL per subject. After processing an average of 1 mL of collagen matrix was obtained from each 100 mL of fat. Significant viable cell markers were present in descending order for adipocytes > CD90+ > CD105+ > CD45+ > CD19+ > CD144+ > CD34+. Western blot analysis showed collagen type II, III, IV, and other proteins. Scanning electronic microscope study showed a regular pattern of cross-linked, helical collagen. Additionally, vital staing demonstrated that the cells were still viable after processing.

CONCLUSIONS

Collagen and cells can be easily obtained from liposuctioned fat by ultrasonic separation without alteration of the overall cellular composition of the tissue. Implantation results in new collagen and cellular growth. Collagen matrix with viable cells for autologous use can be obtained from liposuctioned fat and may provide long term results.

LEVEL OF EVIDENCE

5.

Hyaluronan Hybrid Cooperative Complexes as a Novel Frontier for Cellular Bioprocesses Re-Activation

Hyaluronic Acid (HA)-based dermal formulations have rapidly gained a large consensus in aesthetic medicine and dermatology. HA, highly expressed in the Extracellular Matrix (ECM), acts as an activator of biological cascades, stimulating cell migration and proliferation, and operating as a regulator of the skin immune surveillance, through specific interactions with its receptors. HA may be used in topical formulations, as dermal inducer, for wound healing. Moreover, intradermal HA formulations (injectable HA) provide an attractive tool to counteract skin aging (e.g., facial wrinkles, dryness, and loss of elasticity) and restore normal dermal functions, through simple and minimally invasive procedures. Biological activity of a commercially available hyaluronic acid, Profhilo®, based on NAHYCO™ technology, was compared to H-HA or L-HA alone. The formation of hybrid cooperative complexes was confirmed by the sudden drop in η0 values in the rheological measurements. Besides, hybrid cooperative complexes proved stable to hyaluronidase (BTH) digestion. Using in vitro assays, based on keratinocytes, fibroblasts cells and on the Phenion® Full Thickness Skin Model 3D, hybrid cooperative complexes were compared to H-HA, widely used in biorevitalization procedures, and to L-HA, recently proposed as the most active fraction modulating the inflammatory response. Quantitative real-time PCR analyses were accomplished for the transcript quantification of collagens and elastin. Finally immunofluorescence staining permitted to evaluate the complete biosynthesis of all the molecules investigated. An increase in the expression levels of type I and type III collagen in fibroblasts and type IV and VII collagen in keratinocytes were found with the hybrid cooperative complexes, compared to untreated cells (CTR) and to the H-HA and L-HA treatments. The increase in elastin expression found in both cellular model and in the Phenion® Full Thickness Skin Model 3D also at longer time (up to 7 days), supports the clinically observed improvement of skin elasticity. The biomarkers analyzed suggest an increase of tissue remodeling in the presence of Profhilo®, probably due to the long lasting release and the concurrent action of the two HA components.

The Hyaluronic Acid Fillers: Current Understanding of the Tissue Device Interface

The article is a detailed update regarding cosmetic injectable fillers, specifically focusing on hyaluronic acid fillers. Hyaluronic acid-injectable fillers are used extensively for soft tissue volumizing and contouring. Many different hyaluronic acid-injectable fillers are available on the market and differ in terms of hyaluronic acid concentration, particle size, cross-linking density, requisite needle size, duration, stiffness, hydration, presence of lidocaine, type of cross-linking technology, and cost. Hyaluronic acid is a natural component of many soft tissues, is identical across species minimizing immunogenicity has been linked to wound healing and skin regeneration, and is currently actively being studied for tissue engineering purposes. The biomechanical and biochemical effects of HA on the local microenvironment of the injected site are key to its success as a soft tissue filler. Knowledge of the tissue-device interface will help guide the facial practitioner and lead to optimal outcomes for patients.

Long-lasting and bioactive hyaluronic acid-hydroxyapatite composite hydrogels for injectable dermal fillers: Physical properties and in vivo durability

Hyaluronic acid (HAc)–hydroxyapatite (HAp) composite hydrogels were developed to improve the biostability and bioactivity of HAc for dermal filler applications. Two kinds of HAc-HAp composite fillers were generated: HAcmicroHAp and HAc-nanoHAp composites. HAc-microHAp was fabricated by mixing HAp microspheres with HAc hydrogels, and HAc-nanoHAp was made by in situ precipitation of nano-sized HAp particles in HAc hydrogels. Emphasis was placed on the effect of HAp on the durability and bioactivity of the fillers. Compared with the pure HAc filler, all of the HAc-HAp composite fillers exhibited significant improvements in volumetric maintenance based on in vivo tests owing to their reduced water content and higher degree of biointegration between the filler and surrounding tissues. HAc-HAp composite fillers also showed noticeable enhancement in dermis recovery, promoting collagen and elastic fiber formation. Based on their long-lasting durability and bioactivity, HAc-HAp composite fillers have great potential for soft tissue augmentation with multifunctionality.

Hyaluronan viscosupplementation: state of the art and insight into the novel cooperative hybrid complexes based on high and low molecular weight HA of potential interest in osteoarthritis treatment

Osteoarthritis (OA) represents a group of chronic, painful, disabling conditions affecting synovial joints. It is characterized by degeneration of articular cartilage, alterations of peri-articular and subchondral bone, low-grade synovial inflammation (synovitis). Despite OA is commonly described as a non-inflammatory disease, it is known that its progression and the subsequent increment of symptoms correlate to the production of inflammatory factors that induce the secretion of enzymes responsible for cartilage degradation. In clinical practice, to alleviate pain and stiffness, not only during acute phases but also as maintenance therapy, intra-articular injections of corticosteroids or similar drugs are used, besides it is well diffused the viscosupplementation procedure based on hyaluronan gel. There are many different products containing high molecular weight linear HA or cross-linked derivatives, however the novelty in the field consist in the hybrid cooperative complexes derived from high and low molecular weight HA through a patented processing. This technique permit to double the amount of HA delivered to the injured site without increasing the injected volume, beside in vitro assay on human chondrocytes suggested hybrid complexes as effective in the modulation of several inflammatory cytokines in joints.

Strong and Biostable Hyaluronic Acid-Calcium Phosphate Nanocomposite Hydrogel via in Situ Precipitation Process

Hyaluronic acid (HAc) hydrogel exhibits excellent biocompatibility, but it has limited biomedical application due to its poor biomechanical properties as well as too-fast enzymatic degradation. In this study, we have developed an in situ precipitation process for the fabrication of a HAc-calcium phosphate nanocomposite hydrogel, after the formation of the glycidyl methacrylate-conjugated HAc (GMHA) hydrogels via photo-cross-linking, to improve the mechanical and biological properties under physiological conditions. In particular, our process facilitates the rapid incorporation of calcium phosphate (CaP) nanoparticles of uniform size and with minimal agglomeration into a polymer matrix, homogeneously. Compared with pure HAc, the nanocomposite hydrogels exhibit improved mechanical behavior. Specifically, the shear modulus is improved by a factor of 4. The biostability of the nanocomposite hydrogel was also significantly improved compared with that of pure HAc hydrogels under both in vitro and in vivo conditions.

Dual crosslinked hyaluronic acid nanofibrous membranes for prolonged prevention of post-surgical peritoneal adhesion

A HA NFM crosslinked with FeCl₃and BDDE shows prolonged degradation to prevent peritoneal adhesion.

Injectable gellan gum-based nanoparticles-loaded system for the local delivery of vancomycin in osteomyelitis treatment

Infection spreading in the skeletal system leading to osteomyelitis can be prevented by the prolonged administration of antibiotics in high doses. However systemic antibiotherapy, besides its inconvenience and often low efficacy, provokes numerous side effects. Thus, we formulated a new injectable nanoparticle-loaded system for the local delivery of vancomycin (Vanc) applied in a minimally-invasive way. Vanc was encapsulated in poly(L-lactide-co-glycolide) nanoparticles (NPs) by double-emulsification. The size (258 ± 11 nm), polydispersity index (0.240 ± 0.003) and surface potential (-25.9 ± 0.2 mV) of NPs were determined by dynamic light scattering and capillary electrophoresis measurements. They have a spherical morphology and a smooth topography as observed using atomic force microscopy. Vanc loading and encapsulation efficiencies were 8.8 ± 0.1 and 55.2 ± 0.5 %, respectively, based on fluorescence spectroscopy assays. In order to ensure injectability, NPs were suspended in gellan gum and cross-linked with Ca(2+); also a portion of dissolved antibiotic was added to the system. The resulting system was found to be injectable (extrusion force 11.3 ± 1.1 N), reassembled its structure after breaking as shown by rheology tests and ensured required burst release followed by sustained Vanc delivery. The system was cytocompatible with osteoblast-like MG-63 cells (no significant impact on cells' viability was detected). Growth of Staphylococcus spp. reference strains and also those isolated from osteomyelitic joints was inhibited in contact with the injectable system. As a result we obtained a biocompatible system displaying ease of application (low extrusion force), self-healing ability after disruption, adjustable drug release and antimicrobial properties.