Process for separating proteins fibrinogen, factor XIII and biological glue from a solubilized plasma fraction and for preparing lyophilised concentrates of said proteins

1. A process for preparing a freeze-dried fibrinogen concentrate comprising the steps of:

a) loading an anion exchanger of weak base type with a Cohn fraction I, said exchanger being previously equilibrated with a first buffer having a predetermined ionic strength of an alkaline pH, thus allowing the retention of the biological glue containing fibrinogen and Factor XIII (FXIII),

b) eluting the biological glue with a second buffer having an alkaline pH and an ionic strength greater than said first buffer,

c) separating FXIII from fibrinogen by precipitation of FXIII by addition of at least one chemical agent to the eluted biological glue, wherein the chemical agent precipitating the FXIII is present in the form of an aqueous solution based on citrate salts 1 M,

d) recovering the supernatant solution containing fibrinogen,

e) concentrating the fibrinogen solution,

f) diafiltering the concentrated fibrinogen solution, followed by freeze-drying the fibrinogen solution.

2. The process according to claim 1 , wherein said first buffer has an ionic strength of less than 0.2.

3. The process according to claim 1 , wherein the pH of said first buffer is in the range of values higher than 7 up to 9.

4. The process according to claim 1 , wherein the process includes, prior to the biological glue elution step, a washing step with said first buffer of the anion exchanger until not retained proteins and contaminants are removed.

5. The process according to claim 1 , wherein the biological glue elution is carried out with said second buffer having an ionic strength in a range between 0.5 and 1.3, the pH of which is set to a value of 7.4-7.6.

6. The process according to claim 5 , wherein said second buffer further contains a mixture from 10 to 12 g/l of trisodium citrate, from 1 to 5 g/l of lysine, from 1 to 5 g/l of glycine, from 2 to 5 g/l of Tris, from 25 to 50 g/l of arginine and from 5 to 15 g/l of isoleucine.

7. The process according to claim 1 , wherein the diafiltration is carried out against a buffer containing trisodium citrate, lysine, glycine, arginine and isoleucine.

8. The process according to claim 1 , further comprising at least one step of viral inactivation and/or viral and contaminants removal treatment, selected from the group consisting of a chemical viral inactivation treatment, a nanofiltration and a dry heat viral inactivation treatment.

9. The process according to claim 8 , wherein the nanofiltration is carried out with the diafiltered fibrinogen, prior to freeze-drying.

10. The process according to claim 1 , wherein a concentration step by ultrafiltration is carried out prior to the step of diafiltration or following to the said step, prior to freeze-drying.

11. The process according to claim 1 , including prior to step a), an initial prepurification step of the Cohn fraction I by a classical pretreatment with aluminium hydroxide and/or by a precipitation at low temperature.

12. A freeze-dried fibrinogen concentrate, obtained by the process according to claim 1 , wherein said concentrate contains a mixture from 10 to 12 g/l of trisodium citrate, from 1 to 5 g/l of lysine, from 1 to 5 g/l of glycine, from 2 to 5 g/l of Tris, from 25 to 50 g/l of arginine and from 5 to 15 g/l of isoleucine.