Injectable medical devices are products that are in direct contact with
the patients skin and mucosa for extended periods of time.
The complete absence of systemic and, first and foremost, direct
cellular toxicity is the essential requirement for a filler that is implanted in
the skin and remains there for 8 months (on average).
For this reason in particular, in order to exclude even the lowest of
cytotoxic effects, increasingly sensitive cytotoxicity assays are needed - which
means performing in vitro tests using immortalised human keratinocytes as cell
Cytotoxicity can be assessed with the MTT test, which relies on
mitochondrial activity. The test, originally developed by Mosman in 1983, is
simple, accurate and yields reproducible results (Mosman, 1983). The MTT test is
based on the principle that, in most viable cells, mitochondrial activity is
constant, so an increase or decrease in the number of cells is directly
proportional to mitochondrial activity. Viable cells convert MTT tetrazolium
salts into formazan crystals, which can be solubilised in dimethyl sulphoxide
(DMSO) for homogeneous spectrophotometric measurement. Therefore any change in
the number of viable cells can be detected by measuring the optical density of
formazan at 570 nm.
NEAUVIA STIMULATE Hydrogel 26 mg of HA with 1 % hydroxyapatite has
shown complete absence of cytotoxicity at various concentrations, even ones
higher than the normal concentration used for clinical purposes.
NEAUVIA STIMULATE is a "hybrid" filler, new, safe and reversible, which
concentrates in a single product both the tissue filling functions of a filler
and the collagen production of particle fillers, which already have successfully
been on the market for years. The amount of collagen produced by NEAUVIA
STIMULATE is comparable to particle fillers, without having the problem of being
irreversibile. NEAUVIA STIMULATE is recommended for interventions on hands,
cheeks, nasoslabial and jaw area, and the aesthetic corrections last
approximately 12 months.