Hello friends!
This week, I’ve
been learning about the use of cell cultures to test chemical toxicity. This is an important topic right now, as
industry prepares to meet the deadlines associated with the REACH
legislation. In particular, the widely
used Balb/c 3T3 cell line brings up some interesting points about the extent to
which cell culture systems can be considered truly “in vitro”.
Balb/c 3T3 clone A31 fibroblasts, 72 hours post seeding
As a bit of
background, the cells were originally isolated from a single mouse embryo back
in 1968. They were
continuously cultured according to a strict regimen and underwent spontaneous
transformation, meaning that they can now be cultured indefinitely. [For the purpose of Good Cell Culture Practice, XCellR8
adopts a maximum passage number (p100) at which the cells may be used in our
laboratory, to ensure optimal data quality – and we would recommend this
practice]. Balb/c 3T3 fibroblasts are
cultured in DMEM supplemented with foetal bovine serum (FBS) and
L-Glutamine. So they are animal cells, cultured using some animal-derived products.
There's no
doubt that cell culture technology has enabled huge advances in terms of
replacing animal tests over the past few decades. However, sometimes it's
still necessary to use animal derived cells, media components and reagents,
such as Balb/c 3T3s cultured in serum-containing medium. Sometimes,
industry is forced into doing this because the current OECD Test Guideline for
a particular test may cite the use of an animal cell line. To produce
safety data in compliance with regulations, the OECD published protocol must be
adhered to. One example is OECD Test Guideline 129 (Acute Toxicity),
which utilises the Balb/c 3T3 cell line and the Neutral Red Uptake (NRU) assay
to predict the cytotoxic potential of chemicals.
Scientifically,
there is an alternative: it is possible to carry out the same cytotoxicity test
using human cells (eg epidermal keratinocytes or dermal fibroblasts) cultured
in serum-free media. Even though this
involves some additional cost, it improves the ethical value of the test,
making it truly “in vitro”. Here at XCellR8 we would like to see a new
protocol for the Acute Toxicity test, using human fibroblasts in serum-free
medium, validated for acceptance as a new OECD test guideline.
We also
have a policy of using human cells and completely animal product-free culture
systems wherever it is possible to do so.
In recent years there have been lots of advances in developing
serum-free and chemically defined culture media and reagents. We’d like to encourage the wider use of these
systems and there’ll be more info to follow.
What do
you think about these issues? Feel free
to add your comments here or email us at info@x-cellr8.com.
Catch up again very soon!
Cellwyn
