A novel function for selenium in biological system: Selenite as a highly effective iron carrier for Chinese hamster ovary cell growth and monoclonal antibody production

Abstract

As the market for biopharmaceuticals especially monoclonal antibodies (MAbs) rapidly grows, their manufacturing methods are coming under increasing regulatory scrutiny, particularly due to concerns about the potential introduction of adventitious agents from animal-sourced components in the media used for their production in mammalian cell culture. Chinese hamster ovary (CHO) cells are by far the most commonly used production vehicles for these recombinant glycoproteins. In developing animal-component free media for CHO and other mammalian cell lines, the iron-transporter function of serum or human/bovine transferrin is usually replaced by certain organic or inorganic chelators capable of delivering iron for cell respiration and metabolism, but few of them are sufficiently effective. Selenium is a well-known essential trace element (TE) for cell growth and development, and its positive role in biological system includes detoxification of free radicals by activating glutathione peroxidase. In cell culture, selenium in the form of selenite can help cells to detoxify the medium thus protect them from oxidative damage. In this presentation, we describe the discovery and application of a novel function of selenite, that is, as a highly effective carrier to deliver iron for cell growth and function. In our in-house-developed animal protein-free (APF) medium for CHO cells, using an iron-selenite compound to replace the well-established tropolone delivery system for iron led to comparable or better cell growth and antibody production. A high cell density of >10 x 10(6) viable cells/mL and excellent antibody titer of approximately 3 g/L were achieved in 14-day fed-batch cultures in shake flasks, followed by successful scale-up to stirred bioreactors. The preparation of the commercially unavailable iron-selenite compound from respective ions, and its effectiveness in cell-culture performance, were dependent on reaction time, substrates, and other conditions.

The role of antioxidants in sperm freezing: a review

“…Moreover, a greater percentage of bovine sperm was motile when Se is added prior to freezing (Zhang et al 2006). Dorostkar et al (2012) showed that in frozen-thawed water buffaloes semen, extenders containing 1 and 2 lg mL -1 Se significantly ameliorated sperm motility, viability, membrane integrity and semen total antioxidant capacity and also caused lower DNA damaged sperms.…”

“…Its positive role in biological system contains detoxification of free radicals by activation of glutathione peroxidase, a key enzyme in the defence against oxidative stress, and its function as a cofactor of glutathione synthetase. It was demonstrated that in the cell culture, Se in the form of selenite detoxifies the medium to protect cells from oxidative damage (Zhang et al 2006). It has been indicated that dietary Se supplementation enhanced reproductive function in mice, sheep and cattle (Chiachun et al 1991;Sanders 1984;Tang et al 1991) and also brought about the improvement in post-thaw semen quality of Barbari bucks .…”

The effects of different concentrations of sodium selenite on the in vitro maturation of preantral follicles in serum-free and serum supplemented media

“…During in vitro culture and maturation of follicles, the development of follicles and subsequent embryo may be affected by the free radicals [18][19][20] and in this regard the investigators have been introducing the addition of appropriate antioxidant such as ascorbic acid and selenium [13][14][15][21][22][23][24]. Selenium (Se) is an essential trace element that is necessary for the maintenance of various physiological processes [24].…”

Rational development of a serum-free medium and fed-batch process for a GS-CHO cell line expressing recombinant antibody

“…Transferrin, a widely used but expensive growth factor, plays an important role in ferric ion delivery and also acts as an extracellular antioxidant (Knöspel et al 2010). It can be substituted by other synthetic iron chelator and chemically defined small molecule delivery systems, such as tropolone and FAC, selenite, ferric citrate and vitamin C and other iron agents (Rourou et al 2009;Zhang and Robinson, 2005;Zhang et al 2006). Our results demonstrated that the iron compound FAC was an important factor for the increased antibody titer.…”