Nature and nurture impact on bioactives components – on farm manipulation – phase 1

Summary

Fetal bovine serum is a complex natural product, containing a mix of biomolecules with both growth promoting and growth inhibitory actions. FBS is used in cell culture to support cell proliferation and maintenance. As a natural product, the composition of serum is highly variable however, introducing batch to batch variation in the ability to support cell growth, a problem for high yield cell culture.

It is envisaged that genetic and physiological differences between the donor animals which underlie this variation could be exploited to the benefit of the whole value chain, with producers and processors able to make the biggest contribution and therefore claim a significant share of this benefit. Candidate bioactives have been identified from the literature, based on those required for cell
growth and maintenance and those which varied with FBS bioactivity, with the priority candidates being: the insulin-like growth factors (IGFs) and their binding proteins (IGFBPs), the fibroblast growth factors (FGFs), transforming growth factor (TGF), the epidermal growth factors (EGF) and the neuregulins (NRGs). 

The evidence for both “nature and nurture” (genetics and environment) being able to affect these candidate and other biochemical factors in fetal bovine serum, which are able to impact cell growth and protein production, was then reviewed. The literature relating to other species was also reviewed. The review aimed to address three questions:

What is the evidence that breed of cattle or of sheep can influence biochemicals in blood serum, likely to influence growth of developing cells or of mammalian cell culture?

• Specific intersubspecies crosses can substantially influence fetal IGF-I, depending upon sex of the fetus.
• The effects of breed and genetics on fetal plasma levels of other candidate bioactives are unknown.

What is the evidence that environmental factors such as nutrition, temperature, season, drought can result in biochemical changes in blood serum likely to influence growth of developing cells or of mammalian cell culture?

• The effects of these environmental factors on fetal plasma levels of other candidate
  bioactives are unknown in the bovine.
• Nutrition and oxygen can alter fetal plasma levels of IGFs or related factors (ovine)
• Certain maternal micronutrients can substantially alter plasma IGF-2 in neonates (rodents).

What is the evidence that physiological condition such as age, gender, pregnancy, size of animal, stress, can result in biochemical changes in blood serum likely to influence growth of developing cells or of mammalian cell culture?

• Increasing gestation substantially increases fetal plasma levels of candidate bioactives, including IGF-I, IGF-2, as well as other growth promoting hormones.
• Increasing fetal weight increases plasma IGF-I, but not IGF-2, in late gestation.
• The effects of gestation, fetal size and stress on fetal plasma levels of other candidate bioactives are unknown.

There is evidence for major effects of genetics, environment and gestation on fetal bovine serum levels of one (IGF-I) or more of the major bioactives, able to influence cell growth and survival. There are major gaps in knowledge about the presence and/or modulation of levels of most candidate bioactives by such factors, however, and in whether these can account for the observed variations in bioactivity of batches of FBS. There is the opportunity to cost effectively address these gaps through identification of relevant past, current or future projects or the design of on farm and harvesting projects to provide samples for investigation. 

The future applications of such knowledge may take the form of modifications to on-farm and/or harvesting practices, including the development of new manipulations to mimic effects of IVF on fetal serum IGF-1 to produce product specifically for FBS.

Future research

1. The effects of intersubspecies crosses, gestation, fetal sex and weight and maternal weight and condition on fetal serum levels of candidate bioactives (Tables 1, 2; prioritising IGFs and related factors) be investigated (multiplex assays are available for most of these
   candidate bioactives).
2. The feasibility of defining the effects of genetic, environmental and physiological factors on fetal serum bioactives be investigated by survey of
   • MLA supported projects and other relevant projects in the bovine to identify those which offer archived samples for analysis.
   • On farm and harvesting practices, which would enable collection of samples classified according to some factors.
3. Concentrations of candidate bioactives be measured in batches of FBS and correlated with bioactivity in various culture systems.
4. The effects of IVF on fetal serum concentrations of candidate bioactives and bioactivity in different culture systems be determined and correlated.
5. The effects of selected micronutrient supplementation of the mother and its timing (targeting epigenetic state) on fetal serum concentrations of candidate bioactives and bioactivity in different culture systems be determined and correlated.