Intradermal Injection of Hybrid Complexes of High- and Low-Molecular-Weight Hyaluronan: Where Do We Stand and Where Are We Headed in Regenerative Medicine?

Hyaluronic acid (HA) is a remarkably multifaceted biomacromolecule, playing a role in regulating myriad biological processes such as wound healing, tissue regeneration, anti-inflammation, and immunomodulation. Crosslinked high- and low-molecular-weight hyaluronic acid hydrogels achieve higher molar concentrations, display slower degradation, and allow optimal tissue product diffusion, while harnessing the synergistic contribution of different-molecular-weight hyaluronans. A recent innovation in the world of hyaluronic acid synthesis is represented by NAHYCO® Hybrid Technology, a thermal process leading to hybrid cooperative hyaluronic acid complexes (HCC). This review summarizes the current literature on the in vitro studies and in vivo applications of HCC, from facial and body rejuvenation to future perspectives in skin wound healing, dermatology, and genitourinary pathologies.

Development and Validation of IBSA Photographic Scale for the Assessment of Neck Laxity.

OBJECTIVE: To describe the development and validation of the 5-grade photographic IBSA Neck Laxity Scale. METHODS: The scale was developed from 2 real images, which led to the creation of 5 morphed images, representing different degrees of severity of laxity of the neck. For validation, a set of 50 images (25 real and 25 morphed) was created and sent for evaluation to 6 trained raters (physicians) in 2 rounds, 1 month apart. Raters had to assess each image according to the 5-image scale. Inter-rater and intra-rater reliability in both rounds was evaluated. RESULTS: As to intra-rater reliability, single rater kappa scores between 0.69 and 0.87, and a global kappa score of 0.78 were observed. Inter-rater agreement was measured by means of the intra-class correlation coefficient and scores higher than 0.85 were reported, indicating excellent reliability. CONCLUSION: IBSA Neck Laxity Scale is a validated and reliable scale.

Cannula Versus Sharp Needle for Placement of Soft Tissue Fillers: An Observational Cadaver Study.

BACKGROUND: Soft-tissue fillers have become important products for facial rejuvenation. Deep fat compartments and facial bones lose volume during the natural aging process. For the most natural-looking results, deep volumetric injections at strategic sites are therefore preferred. Supraperiosteal placement is performed with a sharp needle or a non-traumatic cannula. OBJECTIVES: The primary objective was to determine whether there is a difference in precision between supraperiosteal placement with a sharp needle compared with a non-traumatic cannula in cadaver specimens. A secondary objective was to analyze the safety profiles of both injection techniques. METHODS: Cadaver heads were injected with dye material and soft-tissue fillers at multiple aesthetic facial sites on the supraperiosteum and subsequently dissected for observation of dye and filler placement. RESULTS: The non-traumatic cannula technique resulted in product being confined to the deep anatomic layers. In contrast, with the sharp needle technique, material was placed in multiple anatomic layers, from the periosteum to more superficial skin layers. For both techniques results were consistent for all facial sites. CONCLUSIONS: Although direct extrapolation from cadavers to the in vivo situation cannot be made, cannulae showed more precision in placement of product. With the sharp needle, the material was injected on the periosteum, and then migrated in a retrograde direction along the trajectory of the needle path, ending up in multiple anatomic layers. The sharp needle technique also showed a higher complication risk with intra-arterial injection occurring, even though the needle tip was positioned on the periosteum and the product was injected with the needle in constant contact with the periosteum.