Buying "bargain" FBS

With FBS prices continuing to escalate due to the high cost of raw materials, FBS substitute products are becoming commonplace in the market.  These include RMBIO’s Fetalgro® among many others.  These products are generally made up of a serum base blended with a proprietary mix of supplements so that the finished product performs very similarly to FBS.  These kinds of serum products are far more price-stable than FBS and are readily available, making them an excellent and cost effective alternative to FBS.

But what if a lab requires FBS?  With manufacturer pricing now well over $300/bottle and retail pricing often topping $500/bottle, many labs experience sticker shock when they call to order serum and learn the price is 40% to 60% higher than it was last year.  As these users seek out low cost FBS, some unscrupulous serum suppliers offer FBS substitutes labeled as true FBS.  Often these products are sold for $50-$100 per bottle less than current FBS pricing, so to the buyer they appear as bargain FBS.  If they perform equally for you, maybe they are equivalent to a “bargain,” unless you consider that these products are available for a third of the cost of FBS when purchased labeled properly as the FBS substitute rather than as FBS!  For example, Fetalgro® is available for $100 per bottle, a 75% savings over standard US FBS pricing at this time.

Is it FBS?

The best way to ensure the product you receive is really FBS is to buy from a reputable supplier.  A serum substitute will appear identical to FBS.  These products are formulated to perform and test just like FBS, so testing specifications on the Certificate of Analysis will mirror standard FBS results.  One difference is that often FBS substitutes will not report the IgG content on the Certificate of Analysis.  Since many of these products are a blend of serum from older animals which were therefore exposed to environmental factors with a resulting immune response, the IgG level is likely to be very high compared to actual FBS.  Alternatively, an FBS substitute may have an FBS base that is diluted and then has supplements added back so it performs like standard FBS.  In this case, the IgG level may be abnormally low.  There is no recommended or standard level of IgG for FBS, however one would expect a range of roughly 70-200 ug/mL.  If the count is in the thousands, or IgG is not included on the COA, the product is suspect as FBS.  The only way to be sure is to send the sample for independent testing.

An electrophoretic profile (EP) is another cost effective method to analyze gamma globulin levels.  Standard protein electrophoretic profiles for FBS, Newborn Calf Serum, and Fetalgro® Growth Serum are pictured in Figures 1-3.  In the FBS tracing, note the beta and gamma globulin tail trails off very quickly (see Figure 1).  

Some veterinary university labs will perform an EP, and the cost is generally less than $100.  Reported results may be presented in different formats; Colorado State University can provide an EP tracing similar to Figures 1- 3.  When sending material for IgG or EP testing, samples should remain frozen and be submitted on dry ice to ensure the integrity of the product.  The submitted samples should be representative of the larger lot.

Figure 1. Labeled diagram of EP typical of FBS


Why is there so much variability in pricing among FBS substitutes?
 
If FBS substitutes are made up of a base serum plus supplements, why do they vary from $100 to $350+ in pricing?  The base serum has the biggest impact on finished product pricing.  At RMBIO, we use a calf serum base, which is a readily available and relatively inexpensive raw material.  Other products use a blend of different types of serum, and may even include some proportion of FBS.  As a result, it is useful to try several products to determine which one performs best in a particular lab application or cell type.


  

Figure 2. Electrophoretic profile of a lot of Newborn Calf Serum


 

Figure 3. Electrophoretic profile of a lot of Fetalgro Bovine Growth Serum



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