Process for the preparation of endotoxin-free or endotoxin-depleted nucleic acids and/or oligonucleotides for gene therapy

In a method comprising linking therapeutically active nucleic acids, oligonucleotides, or combination thereof to a transfection vector, the improvement wherein the therapeutically active nucleic acids, oligonucleotides, or combination therefor are obtained from a biological source of raw cells by a method comprising, the steps of:

• (a) lysing the raw cells in said biological source to obtain a raw fraction of the nucleic acids, oligonucleotides, or combination thereof;
• (b) applying said raw fraction on an anion exchanger, which anion exchanger begins desorbing DNA and RNA at different ionic strengths, the ionic strength at which DNA begins desorbing corresponding to a sodium chloride solution having a concentration higher by at least 100 mM than the concentration of a sodium chloride solution corresponding to the ionic strength at which RNA begins desorbing, thereby isolating the nucleic acids, oligonucleotides, or combination, thereof;
• (c) eluting the nucleic acids, oligonucleotides, or combination, thereof, from the anion exchanger to obtain a separated fraction of the nucleic acids, oligonucleotides, or combination, thereof;
• and
• (d) treating after either step (a) or step (c), the nucleic acids or oligonucleotides with non-ionic detergents, affinity chromatographic supports, or inorganic chromatographic material, thereby effecting removal of endotoxinis.