Heamoglobin and uses thereof

A composition for in vitro cell culture, comprising:

• A) a serum-free nutritive cell culture medium solution for the maintenance, growth, propagation, and/or expansion of cells in an artificial environment outside of a multicellular organism or tissue,
• B) a purified and function hemoglobin isolated from Nereis virens, wherein said hemoglobin has no free cysteine and no glycosylations,
• said hemoglobin having:
• (i) a P50 from 5 to 15 mm Hg at 6-7° C.,
• (ii) a P50 from 12 to 20 mm Hg at 16-17° C., and
• (iii) a P50 from 20 to 50 mm Hg at 36-37° C.,
• C) a buffer,
• D) isolated cells which grow and produce a recombinant protein, and
• wherein components A), B), C), and D) are in mixture in the cell culture medium solution, and
• wherein of the hemoglobin has a concentration of at least 0.050 g/l.