Cross-linked hyaluronic acid, process for the preparation thereof and use thereof in the aesthetic field
The present invention relates, in one aspect, to the use as dermal filler of a cross-linked biopolymer compatible with the tissues of the human organism based on hyaluronic acid cross-linked with urea. The biopolymer of hyaluronic acid and urea may be applied or injected in a soft tissue of human body for tissue augmentation.
1. A method for tissue augmentation of an individual, said method comprising:
injecting under the skin of said individual, a biocompatible cross-linked biopolymer wherein said biopolymer consists of hyaluronic acid cross-linked with urea.
2. A method according to claim 1 , wherein the biopolymer has a molecular weight in the range from 100,000 to 20,000,000 Dalton.
3. A method according to claim 1 , wherein the biopolymer is in the form of a hydrogel or particles.
4. A method according to claim 1 , wherein the biopolymer is injected or implanted in the epidermis, dermis, or hypodermis of said individual.
5. A method according to claim 1 , wherein the biopolymer is in the form of an implant or of a subcutaneous filling injection for the treatment of aging.
6. The method of claim 1 for the cosmetic or aesthetic treatment of lines, wrinkles, folds or furrows associated with face aging of a subject in need of an aesthetic treatment.
7. The method of claim 1 , wherein the tissue augmentation is for the treatment of lines, wrinkles, folds, or furrows.
8. A method for the manufacture of a hyaluronic acid biopolymer cross-linked with urea said method comprising:
a) dissolving hyaluronic acid or a salt thereof in a liquid to form a solution of hyaluronic acid;
b) dissolving urea in an aqueous acidic solution with a pH of 3.5 to 4 to form an acidic aqueous solution of urea;
c) combining the solution of hyaluronic acid with the acidic aqueous solution of urea to obtain a mixture, said mixture having a pH in the range of 3.5 to 4, wherein said hyaluronic acid biopolymer crosslinked with urea is formed as a result of said combining.
9. The method according to claim 8 , wherein the acidic aqueous solution of urea contains HCl preferably in a concentration in the range from 20 to 30% by weight.
10. The method according to claim 8 , wherein the hyaluronic acid dissolved in solution is in the form of sodium or calcium salt.