FACIAL INJECTABLE TREATMENTS |
HYDROLIFT™ action: a new strategy for controlling cutaneous homeostasis
GIANFRANCO TAJANA, Department of Pharmaceutical Sciences of the University of Salerno.
T
he many surprising functions of the cutis can be attributed to the molecular composition of its
extracellular matrix and, in particular, the biological properties of one of the main components: hyaluronan (hyaluronic acid). Approximately half of the
hyaluronan in our body is distributed in the cutaneous region where fibroblasts, keratinocytes and endothelial cells of the dermal microcirculation synthesise with different molecular weights, producing families of hyaluronan ranging from 50 000 kD (low weight) to 2 000 000 kD (high weight)1
. Overall, their half-life does not
exceed 2 days and is defined by the balance established between 'production' and 'destruction', given by a synthesis system (HA synthase 1–3)2
and a demolition
(HYAL 1 and 2) system, respectively3
. Once the varying classes of
hyaluronan have been synthesised, they operate in harmony with the different cutaneous compartments, where they interact with specific receptors (CD44, RHAMM, LYVE-1), triggering different cell responses and metabolic reactions4
.
Approximately one third of the cutaneous hyaluronan is contained in the epidermis5
where, on
binding with the CD44 receptor, it works as a 'multifunctional mastic', which ensures not only adhesion between the individual keratinocytes, but also intervenes in the regulation of their gene expression6
.
Hyaluronan in the epidemis In the epidermis, hyaluronan, owing to its high negative charge, is localised 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 interactions1 As a result of its special
.
antibacterial properties, hyaluronan takes part in the formation of a cutaneous microenvironment that can promote the activity of the resident microflora and prevent the colonisation and development of pathogens7
; it boosts the natural
defence mechanisms (beta defensin)8
. and activates the
immune system through the 'tool-like' receptor system9 All these prevalent
(but not
exclusive) trophometabolic activities in the low molecular weight hyaluronan class, contribute to the maintenance of the cutaneous homeostasis (HYDRO action). In the same way, in the dermis, the high-weight hyaluronan, through the complex interactions established with the main molecules of the extracellular matrix
(proteoglycans,
Further information email:
info@viscoderm.com
30 ❚
glycoproteins, elastin and the seven different types of collagen), play a central role in the
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maintenance of the structural stability10
.
In particular, they are concentrated around the vascular network forming a hydrophilic coating which recalls, conserves and sorts water and metabolites to the whole matrix, regulating the deformability and plasticity, ensuring the trophism of the
connected with the metabolism (diabetes)18
. In summary, the
'trophic-modelling' action of hyaluronan arises from their synergy and from the activity connected with their molecular weights.
The latter can be produced either by direct synthesis or can
performed by the different molecular weights has stimulated the need to be able to provide hyaluronan in the dermoÐ aesthetic field with different molecular weights and concentrations.
"Increasing knowledge of the functions resident cell populations11 .
Hyaluronan works like a physiological skin expander, occupies the microdomains of the dermal matrix, cancels its depressions, and gives the cutis a smooth and polished macroscopic appearance (LIFT action)12
. Finally, an important role is
carried out at the dermo– epidermal junction, where the levels of hyaluronan control the expansion and deformability of the dermal papillae13
.
Action and interaction The normal turnover of the
different classes of hyaluronan arises from the actions and interactions that they establish with the various molecular and cellular constituents of the cutis. Their activity can be altered by exogenous factors able to modify the turnover, or by the effects of cutaneous ageing14
. The mechanisms responsible
for ageing can be further accelerated by extreme exogenous conditions (radiation, ultraviolet rays, stress)15, 16
or endogenous
conditions (drugs, chemical agents)17
, or by conditions
be self-generated by post-synthesis reduction (high weight – low weight transition), carried out by specific enzyme systems following modifications of physiological homeostasis.
In the cutaneous region,
Hyaluronidase HYAL-1 cooperates with Hyaluronidase HYAL-2 for the reduction of high-weight hyaluronan into tetrasaccharidic fractions of 20 kDa, are absorbed by the fibroblast through vesicles that are formed following the digestion of the glycophosphatidylinositol anchored directly to the HYAL-2. These vesicles, defined by as hyalouronosomes,
Stern19
should be able to regulate both the synthesis and the demolition processes.
Product development It is interesting to observe how, in
the same cutaneous district, hyaluronan with different molecular weights, generated following controlled enzyme reactions, can operate and cooperate19
.
Increasing knowledge of the functions performed by the
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