In science, a black box is a device, system or object which can be viewed solely in terms of its input, output and transfer characteristics without any knowledge of its internal workings, that is, its action is "opaque" (black). Almost anything might be referred to as a black box: an algorithm, a human mind, a transistor or a cell culture medium.
When you are doing cell culture work you put one black box into another black box (cells into cell culture medium).
Anyone has probably experienced that the selection of fetal bovine serum for cell culture work is far from rational. Of course, it has got to be cheap and the cells should be happily growing, but apart from that, relatively little objective measures are applied.
Fetal bovine serum (FBS) (synonym fetal calf serum, FCS) is the sterile liquid that is obtained from the clotted blood of the bovine fetus. It contains numerous factors that are needed for the survival and propagation of mammalian cells in culture and for this reason was introduced early in cell biology research, subsequent to initial studies with hen and sheep sera (Carrel and Ebeling, 1922; Treadwell and Ross, 1963). Already in the 1950s profound differences for cellular growth between human serum and FBS were described and first attempts were made to culture cells in serum-free media (Treadwell and Ross, 1963; Evans and Boyant, 1956). Despite advances in the fabrication of standardized serum-free media over the last decades (van der Valk et al., 2010), FBS still remains the most widely used cell culture medium supplement in cell biology.
FBS is commercially available from numerous manufacturers and researchers typically chose their sera batches based on price, good viability and function of their cell cultures, or cloning efficiency. However, few researchers study the composition of their FBS batches and these sera therefore remain a major black box in cellular experiments. It was previously reported that different sera contain distinct compositions of fatty acids, including arachidonic acid (Lagarde et al., 1984), and that these lipids can directly influence cellular experiments (Stoll and Spector, 1984, Loomis et al, 1983). More recently, it was shown that FBS can contain unknown factors that are able to inhibit Toll-like receptor (TLR) activation under certain circumstances (Bas et al., 2010). Although it is generally accepted that the composition of FBS may directly influence the outcome of cellular experiments, relatively little is known about the impact of lipids.
In a recent study in our laboratory by Janine Marazzi et al. (J. Immunol. Methods) we were able to describe a new algorithm of the black box FBS. We show that the major endocannabinoid 2-AG is able to significantly affect cell culture work. Amazing, if you think about it that we have not managed to standardize our culture conditions to make experiments more comparable. More amazing even if we consider the fact that cell biology is highly descriptive and lacks scientific power (reproducibility, mathematical stringency, predictive value).
I suggest that we make an attempt to profile our cell culture media using state of the art metabolomics technologies - for the sake of insights and scientific progress.
A poem by Arielle Perkins:
I have in my hands two boxes,
Which God gave me to hold.
He said, 'Put all your sorrows in the black box,
And all your joys in the gold.'
I heeded His words, and in the two boxes,
Both my joys and sorrows I stored,
But though the gold became heavier each day,
The black was as light as before.
With curiosity, I opened the black,
I wanted to find out why,
And I saw, in the base of the box, a hole,
Which my sorrows had fallen out by.
I showed the hole to God, and mused,
'I wonder where my sorrows could be! '
He smiled a gentle smile and said,
'My child, they're all here with me..'
I asked God, why He gave me the boxes,
Why the gold and the black with the hole?
'My child, the gold is for you to count your blessings,
The black is for you to let go.'