The present invention relates to a complex nutrient medium, to its applications and more especially to its use for manufacturing a composition for topical use, and in particular for topical cosmetic or medicinal use.
The composition obtained according to the invention enables an extracellular environment which is entirely suited to the epidermis to be obtained, by supplying in particular:
an optimized nutritional provision, both other components in respect of vitamins, trace elements and
and pH and osmolarity characteristics close to physiological conditions.
Generally speaking, according to the invention, the nutritional agent consists of a complex nutrient medium comprising compounds which are both biocompatible, biomimetic and bioavailable in respect of the skin, excluding any biological extract of animal origin, such as foetal calf serum, or of cellular origin.
The complex nutrient medium adopted according to the invention has a composition suitable for permitting, on its own and in an aqueous medium, viable in vitro culture of an inoculum of human epidermal keratinocytes, with at least one clonal proliferation of the latter at the first passage, without a living nourishing substrate such as fibroblasts.
xe2x80x9cBiocompatiblexe2x80x9d is understood to mean the property according to which the compound is harmless to the skin.
xe2x80x9cBiomimeticxe2x80x9d is understood to mean the fact that the compound is present in the natural state in the skin.
xe2x80x9cBioavailablexe2x80x9d is understood to mean the property according to which the compound is assimilable by human epidermal keratinocytes, both in vitro and in vivo.
By routine tests, a person skilled in the art is in a position to formulate a complex nutrient medium according to the invention, in particular by carrying out with the said medium in vitro culturing of keratinocytes, the growth of which can be observed, for example under a microscope.
In this connection, the following documents have already described media suited to in vitro culturing of keratinocytes, the viability and growth of which can be determined by the tests currently in use, and be directly assessed by observation under a microscope:
Boyce ST, Ham RG, Calcium-regulated differentiation of normal human epidermal keratinocytes in defined clonal culture and serum-free serial culture, J. Invest. Dermatol. 1983; 81: 33S-40S
Boyce S T, Ham R G, Cultivation, frozen storage, and clonal growth of normal human epidermal keratinocytes in serum-free media, J. Tissue Culture Methods. 1985; 9: 83-93.
Where necessary, the content of these publications is incorporated in the present description.
The complex nutrient medium according to the invention comprises amino acids, one or more vitamins, one or more organic components and one or more inorganic salts.
A composition of the invention for topical use comprises a phase which is biocompatible with the superficial parts of the human body, in which phase at least the said nutrient medium as defined above is distributed homogeneously.
In a composition according to the present invention, the biocompatible phase in which the nutritional agent is distributed can constitute the excipient, or one of the components of the excipient, of the said composition.
Since all of the compounds present in the nutrient medium according to the invention are water-soluble, two methods of formulation may be employed in order to obtain a composition for topical use:
1) Aqueous continuous phase, containing the nutrient medium according to the invention:
in the form of an aqueous gel, with the aid of a nonionic water-soluble polymer of the polysaccharide or cellulose ether type (polymers compatible with the high ionic strength of the medium);
in the form of an emulsified system (oil-in-water emulsion employing surfactants that withstand high ionic strengths);
in the form of a cosmetic serum.
2) Oily continuous phase, the discontinuous phase containing the nutrient medium according to the invention:
in emulsified form, on the understanding that the ionic strength of the discontinuous phase entails instability of the emulsion; it is, however, possible to formulate lamellar or cylindrical phases having better stability, or alternatively a two-phase system re-emulsified immediately before use by simple shaking;
by encapsulation:
in a rigid capsule of the polysaccharide type, dispersed in the lipid phase,
in a soft capsule of the gelatin type, dispersed in the discontinuous phase.
The use of liposomes as an encapsulation delivery agent can be envisaged in the form of a liposomal gel in an aqueous continuous phase.
A composition according to the invention can serve as a cosmetic base. Its nutritional provision is considerably advantageous for improvement of the viability, maintenance of the integrity and the balance of the superficial cells of the skin. In particular, it enables the primary intrinsic qualities of the skin to be preserved on a long-lasting basis, its resistance to damage to be increased and, where appropriate, its return to a state of balance to be promoted.
Another subject of the invention is a cosmetic preparation comprising a base defined above, in which the complex nutrient medium constitutes either an active principle, or an excipient in the presence of other active principles which it is capable of potentiating.
The complex nutrient medium of the invention can also be used for the preparation or production of a medicament.
The use of such a medium on a weakened skin (irritated or dehydrated skins, older skins, etc) enables the skin to return to a satisfactory state, in terms both of trophicity and of hydration of the superficial layers of the epidermis.
A medicinal composition comprising a complex nutrient medium according to the invention can serve as a pharmaceutical formulation base, in particular a nutrient pharmaceutical formulation base.
It possesses, in addition, pharmacological properties which will be demonstrated in the examples. According to an advantageous application of a medicinal composition of the invention, it is intended for the preservative treatment of grafts after they are removed. It will preferably take the form of a sterile solution which is especially suitable for the cleaning and maintenance of grafts in third-degree burns victims.
In addition, a composition as defined above has efficacious properties for preventing or treating disorders of cicatrization such as bedsores, varicose ulcers, stretch marks and keloids, and/or a delay of cicatrization.
More generally speaking, a composition according to the invention can be incorporated in any preparation for use in a pharmaceutical formulation, as an active principle optionally with other active principles, but also as an excipient as a result of its capacity to potentiate the action of specific active principles.