Method for manufacturing a shaped crosslinked hyaluronic acid product

1. Method for manufacturing a shaped cross-linked hyaluronic acid product, comprising the steps of:

(i) providing a hyaluronic acid substrate dissolved in a first liquid medium, which is an aqueous solution, without any cross-linking;

(ii) precipitating the hyaluronic acid substrate by subjecting it to a second liquid medium comprising an amount of one or more first water-soluble organic solvent(s) giving precipitating conditions for hyaluronic acid without any cross-linking; wherein step (i) and/or step (ii) further comprises arranging the hyaluronic acid substrate in a desired shape; and

(iii) subjecting the non-cross-linked precipitated hyaluronic acid substrate in the desired shape to a single cross-linking reaction in a third liquid medium having a pH of 11.5 or higher and comprising one or more polyfunctional cross-linking agent(s) and an amount of one or more second organic solvent(s) giving precipitating conditions for hyaluronic acid, under suitable conditions to obtain a precipitated, shaped cross-linked hyaluronic acid product,

wherein the aqueous solution of step (i) contains 40-100 vol % water and 0-60 vol % of lower alkyl alcohol(s).

2. Method according to claim 1 , wherein the first two steps (i) and (ii) occur in the absence of a cross-linking agent, and wherein the polyfunctional cross-linking agent(s) is added in the third cross-linking step (iii).

3. Method according to claim 1 , wherein step (i) further comprises arranging the hyaluronic acid substrate solution in a desired shape on a hydrophobic surface; and wherein the precipitation of the shaped hyaluronic acid substrate in step (ii) occurs on said hydrophobic surface.

4. Method according to claim 1 , wherein said shape is selected from the group consisting of a particle, a fibre, a string, a strand, a net, a film, a disc and a bead.

5. Method according to claim 4 , wherein said shape is a fibre and the ratio between its length and its width is 10:1 or higher.

6. Method according to claim 1 , wherein step (ii) involves extruding the hyaluronic acid substrate into the second liquid medium comprising an amount of the first water-soluble organic solvent(s) giving precipitating conditions for hyaluronic acid, thereby allowing the extruded hyaluronic acid substrate to form a precipitated fibre in the second liquid medium.

7. Method according to claim 1 , wherein the second liquid medium of step (ii) contains 0-30 vol % water and 70-100 vol % of the first water-soluble organic solvent(s).

8. Method according to claim 1 , wherein the third liquid medium of step (iii) contains 0-35 vol % water, 65-100 vol % of the second organic solvent(s), and one or more polyfunctional cross-linking agent(s).

9. Method according to claim 1 , wherein the organic solvent(s) is individually selected from one or more lower alkyl alcohol(s).

10. Method according to claim 9 , wherein the lower alkyl alcohol is ethanol.

11. Method according to claim 1 , said polyfunctional cross-linking agent(s) being individually selected from the group consisting of 1,4-butanediol diglycidyl ether (BDDE), 1,2-ethanediol diglycidyl ether (EDDE) and diepoxyoctane.

12. Method according to claim 11 , wherein said polyfunctional cross-linking agent is 1,4-butanediol diglycidyl ether (BDDE).

13. Method according to claim 1 , further comprising the steps of:

(iv) subjecting the precipitated cross-linked hyaluronic acid product to non-precipitating conditions; and

(v) isolating the cross-linked hyaluronic acid product in non-precipitated form.

14. Method according to claim 13 , wherein step (v) further comprises sterilizing the cross-linked hyaluronic acid product.