Efficacy, Safety, and Tolerance of a New Injection Technique for High- and Low-Molecular-Weight Hyaluronic Acid Hybrid Complexes

Carmen Laurino, MSc; Beniamino Palmieri, MD; Alessandro Coacci, MD


ePlasty. 2015;15 

In This Article

Abstract and Introduction


Objective: Facial aging is characterized by skin laxity and loss of skin elasticity. Hyaluronic acid, a biological component of the extracellular matrix, whose level decreases during aging, plays structural, rheological, and physiological roles in the skin. Hyaluronic acid may possess different molecular weights: low-molecular-weight hyaluronic acid (from 50 kDa) and high-molecular-weight hyaluronic acid (just up to 2 million kDa). This monocentric, retrospective, observational study investigates the efficacy, security, and tolerability of a new injective low- and high-molecular-weight hyaluronic acid for facial skin rejuvenation.

Methods: Eleven women received once a month, for 2 months, 2 mL of the product in the subcutaneous layer of the right and left malar/submalar areas. Facial skin echography, facial skin hydration, elasticity, and transepidermal water loss were assessed before (T 0), after 1 month (T 1), and after 3 months of treatment (T 2). The injective features of the product, physician subjective satisfaction, and patient satisfaction were also reported.

Results: Facial face hydration, elasticity, and transepidermal water loss values significantly improved at T 1 and T 2 (P < .01). Patients were very satisfied at the end of the treatment, and the compound's profit evaluated by the physician was optimal in the absence of local side effects.

Conclusions: This treatment represents a good treatment option to restore vitality and turgidity of skin presenting the signs of aging in the absence of intolerance symptoms.


Reduced dermis vascularization and biosynthesis of extracellular matrix by fibroblasts, with subsequent skin laxity and elastic properties loss, are common features of facial aging.[1] Hyaluronic acid (HA), a glycosaminoglycan (GAG) binding water molecules and involved in tissue hydration, is markedly reduced in the aged skin.[2,3] This molecule and its complexes have structural, rheological, physiological, and cell-to-cell functions in the skin: it promotes the fibroblast proliferation and migration, acts as a free radical scavenger, and, due to its optimal water-binding capacity, improves nutrient exchange between vessels and the dermis.[4] Its structure is not species-specific and it is highly biocompatible.[5] More than half of the HA in our body is distributed in the cutaneous region where fibroblasts, keratinocytes, and endothelial cells of the dermal microcirculation synthesize families of HA ranging from 50 kDa (low molecular weight, L-HA) to 2 million kDa (high molecular weight, H-HA).[6] Once the varying classes of HA have been synthesized, they operate in harmony with the different cutaneous compartments, where they interact with specific receptors (CD44, hyaluronan-mediated motility receptors [RHAMM], Lyve-1), triggering different cell responses and biochemical cascades.[7]

In the epidermis, HA, owing to its high negative charge, is localized in the extracellular region, where it forms a hydrophilic network transporting and distributing nutrients and metabolites to the keratinocytes, melanocytes, and the Langerhans cells through a percolation mechanism, establishing important functional interactions.[6] This prevalent, but not exclusive, trophometabolic activity of L-HA contributes to the maintenance of the cutaneous homeostasis. In the same way, in the dermis, H-HA, through the complex interactions with the main molecules of the extracellular matrix (proteoglycans, glycoproteins, elastin, and the 7 different types of collagen), plays a pivotal role in the maintenance of structural stability.[8] HA works like a physiological skin expander, occupies the micro domains of the dermal matrix, cancels its depressions, and gives the cutis a smooth and polished macroscopic appearance.[9]

In summary, the "trophic-modeling" action of HA arises from its synergy and the activity connected with its molecular weights. L-HA can be either produced by direct synthesis or self-generated by postsynthesis reduction (H-HA to L-HA transition), carried out by specific enzyme systems following modifications of physiological homeostasis. Increasing knowledge of the functions performed by the different molecular weights has stimulated the need to be able to provide HA in the derma-aesthetic field, using different molecular weights and concentrations.

The physiological reduction of HA activities in the aged skin contributes to dermal thinning and the formation of folds and wrinkles.[4] The procedure of HA injections in the dermis, defined "viscosupplementation," restores the skin tone, fullness, and elasticity, although native HA remains stable in the dermis only for few days due to the quick degradation by hyaluronidase.[10] For this reason, chemically stabilized cross-linked HA filler has been developed to prolong dermal stability.[4] Although 1,4-butanediol diglycidyl ether is the safest and the most used cross-linking agent, the modern filler technologies aim to reduce the concentration of this chemical compound to increase filler biocompatibility.[11]

The development of increasingly sophisticated synthesis technologies has recently led IBSA Farmaceutici Italia Srl to provide a whole range of HAs at defined concentrations and molecular weights. In particular, the production of novel, stable, molecular hybrids proved feasible through a specific procedure involving a thermal treatment. For the first time, it was possible to combine 32 mg of H-HA (1100–1400 kDa) and 32 mg of L-HA (80–100 kDa) to obtain injectable concentrations of HA unimaginable until now (64 mg in 2 mL). The H-HA–L-HA complex (1:1 weight ratio) was produced following the procedure described in patent application WO2011EP65633.[12] This new product is called Profhilo. Profhilo hybrid complexes proved to protect the H-HA present, reducing 8-fold degradation of HA chains of molecular weight of more than 1000 kDa. Moreover, L-HA is slowly released from the hybrid network; therefore, the first inflammatory cytokines are not upregulated, lowering overall the inflammatory cascade, or limiting the first "inflammation" phase to a positive light shock to "sleeping/tired" cells.

The aim of this monocentric, retrospective, observational study was to investigate the efficacy, security, and tolerability of a new medical device for facial skin rejuvenation.