Methods for freeze-drying and rehydrating biologics
The present invention relates generally to the fields of immunology and vaccine technology. More specifically, the present invention relates to methods for freeze-drying biological preparations, including peptides, antigens, antibodies, and especially, cells. Importantly, the disclosed methods preserve the viability, infectivity and immunogenicity of cells from the Apicomplexa phylum, the Sarcocystidae family, and in particular, cells from the Toxoplasma genus.
1. A lyophilized composition containing freeze-dried protozoa of intracellular nature, wherein said lyophilized composition is devoid of protozoal host cells and contains a moisture content ranging between about 1% to 12% by weight, wherein said protozoa comprise live attenuated strains of Toxoplasma parasites, wherein said lyophilized composition further comprises a cryoprotectant, and wherein said cryoprotectant is present in an effective amount to maintain the ability of more than 1% of said freeze-dried protozoa to be restored to a viable state by reconstitution of the lyophilized composition, and wherein said restored protozoa maintain the ability to vaccinate and effectively protect against Toxoplasma parasite infections.
2. The lyophilized composition of claim 1 , wherein said freeze-dried protozoa are protozoa of fragile state.
3. The lyophilized composition of claim 1 , wherein said freeze-dried protozoa have immunogenic and/or prophylactic activity upon reconstitution.
4. A process for reconstituting the lyophilized composition of claim 1 , comprising adding a rehydration medium to said lyophilized composition, whereby more than 1% of said freeze-dried protozoa are restored to a viable state and maintain the ability to vaccinate and effectively protect against Toxoplasma parasite infections.
5. The process of claim 4 , wherein the rehydration medium is added at a rate ranging from 25 μL per second to 1000 μL per second.
6. The lyophilized composition of claim 1 , wherein the lyophilized composition has been stored at a temperature from −25° C. to 25° C. for longer than two weeks.
7. The lyophilized composition of claim 6 , wherein the lyophilized composition has been stored at a temperature from −25° C. to 2° C.
8. The lyophilized composition of claim 6 , wherein the lyophilized composition has been stored at a temperature 2° C. to 8° C.
9. The lyophilized composition of claim 6 , wherein the lyophilized composition has been stored at a temperature from 8° C. to 25° C.
10. The lyophilized composition of claim 2 , wherein said freeze-dried protozoa are in a tachyzoite state, a bradyzoite state, a sporozoite state, a merozoite state, or any combinations thereof.
11. The lyophilized composition of claim 1 , wherein said cryoprotectant is selected from DMSO, a monosaccharide, a disaccharide, an oligosaccharide, a polysaccharide, or any combinations thereof.
12. The lyophilized composition of claim 11 , wherein the cryoprotectant is sucrose, trehalose, glucose, inulin, or any combinations thereof.
13. The lyophilized composition of claim 11 , further comprising an osmoprotectant.
14. The lyophilized composition of claim 13 , wherein said osmoprotectant is ectoine.
15. The lyophilized composition of claim 11 , further comprising an antioxidant selected from glutathione (GSH), epigallocatechin gallate (EGCG), ascorbic acid, or any combinations thereof.
16. The lyophilized composition of claim 11 , further comprising proline.
17. The process of claim 4 , wherein the rehydration medium is Dulbecco's Modified Eagle Medium (DMEM).
18. The process of claim 4 , wherein the rehydration medium is added at a rate of 250 μL per second.
19. The lyophilized composition of claim 1 , wherein the protozoa are tachyzoites.
20. The lyophilized composition of claim 1 , wherein the lyophilized composition contains a moisture content ranging between about 4% to 12% by weight.
21. A process for obtaining the lyophilized composition of claim 1 , comprising:
a step of primary drying of a frozen suspension comprising live attenuated strains of Toxoplasma parasites par to obtain a primary dried composition, wherein said step of primary drying is carried out at about −55° C., for about 20 h and wherein said step of primary drying is carried out at a pressure comprised from about 30 to about 80 Pa, for 0 to 7 h, and then at a pressure below 2 Pa for the remaining time, and
a step of secondary drying of the primary dried composition to obtain a lyophilized composition with a moisture content of about 1% to 12% by weight, wherein said step of secondary drying is carried out at a pressure below 2 Pa and at a temperature increasing from −55° C. to +5° C. at a rate comprised from about 0.01° C./min to about 0.2° C./min, and wherein said secondary drying comprises a temperature plateau of 1 h at every increase of 15° C., and wherein said temperature being maintained at +5° C. for 4 h when reaching said temperature.
22. The process of claim 21 , wherein the frozen suspension is obtained by freezing a suspension of protozoa for 4 to 23 h, at atmospheric pressure, by lowering the initial temperature of the suspension of protozoa to a temperature comprised from about −40° C. to about −80° C. from an initial temperature of the suspension of protozoa being comprised from about 15° C. to about 25° C., and wherein said lowering of the temperature is carried out at a rate comprised from about −0.1° C./min to about −10° C./min.
23. The process of claim 21 , further comprising an initial step of suspending protozoa in an aqueous formulation solution comprising a culture medium of said protozoa and at least one cryoprotectant, wherein said aqueous formulation solution further comprises at least one osmoprotectant and/or at least one antioxidant and/or at least one other additive, and wherein the culture medium in said aqueous formulation solution is DMEM, RPMI or PBS, the cryoprotectant in said formulation solution is selected from the group comprising DMSO, a monosaccharide, a disaccharide, an oligosaccharide, a polysaccharide, sucrose, trehalose, glucose, inulin or a mixture thereof, the osmoprotectant in said formulation solution is ectoine, the antioxidant in said formulation solution is selected from the group comprising GSH, EGCG, ascorbic acid or a mixture thereof, and the other additive in said formulation solution is selected from polymers, copolymers, amino-acids, in particular L-proline, peptides, proteins or a mixture thereof.
24. The process of claim 23 , wherein said aqueous formulation solution comprises:
a culture medium selected from DMEM, RPMI, or PBS
0 mM to about 3000 mM DMSO,
0 mM to about 300 mM sucrose,
0 mM to about 1000 mM trehalose,
0 mM to about 400 mM (fructose equivalent) inulin,
0 mM to about 400 mM ascorbic acid,
0 mM to about 10 mM EGCG,
0 mM to about 200 mM GSH,
0 mM to about 150 mM proline,
0 mM to about 150 mM ectoine,
provided that the concentration of at least one of the components among DMSO, sucrose, trehalose, inulin, ascorbic acid, EGCG, GSH, proline or ectoine is greater than 0 mM; and wherein the solution is adjusted at pH 7.4 with sodium hydroxide.