Is the quotation for recombinant protein biologics in animal experiments based on U or mg?

Animal experiments require the other party to provide reports on endotoxin, HPLC/SDS-PAGE purity, and specific activity (IU/mg), not just price. High levels of endotoxins may interfere with inflammatory markers in rat models, while low purity may increase the risk of immunogenicity. The glycosylation level and sialic acid modification of EPO from different manufacturers may vary, resulting in differences in half-life and activity in vivo. Therefore, similar specific activity does not necessarily mean consistent efficacy. It is recommended to first purchase samples or 10000 IU specifications for pre experiments to compare changes in hematocrit or reticulocytes, and then lock in the batch. Short delivery time can be inquired through domestic spot channels, but cold chain cannot be saved; Importing may take 2-4 weeks, while domestic research grade/biosimilar drugs may be faster. It is best to purchase enough of the same batch at once to avoid data fluctuations caused by changing batches midway.

It is recommended to compare and administer recombinant proteins such as EPO according to IU, as the specific activity (IU/mg) of different products varies, and mg alone cannot reflect biological activity. When comparing prices, divide the quotation by the IU quantity to obtain the cost per 10000 IU, and then combine the specific activity and specifications. The dosage for rats should refer to the literature. The commonly used range for renal anemia models is 100-500 IU/kg/time, 2-3 times a week. However, the specific dosage should be adjusted according to the model, administration route, and formulation, and should not be directly applied. If the 10000 IU specification is given to 200 g rats at a rate of 200 IU/kg per time, each rat will have approximately 40 IU. One rat can be used multiple times, but there should be a margin for packaging loss. When inquiring, ask the supplier to clarify the IU, specific activity, and buffer solution for each unit. Although the IU units of different products are labeled the same, the in vivo efficacy may vary due to different glycosylation modifications.

The key to 10000 IU fractional preservation is to avoid repeated freeze-thaw and adsorption losses. It is recommended to confirm whether the specification contains carrier proteins (such as HSA) after arrival. If the buffer does not contain carrier proteins and the protein concentration is low, filling it into a normal tube may cause obvious adsorption. Try to use low-protein adsorption tubes in the ultra-clean table to dispense according to a single dose or single group, such as calculating the number of IUs per tube according to the number of animals and the number of doses, leaving 5% -10% loss. Save -80 after filling to avoid freezing and thawing more than 1-2 times; if the instructions allow, you can also store -20 for a short period of time. It is not recommended to use it according to the original expiration date after filling, it is best to use it within 1-3 months, and use the same batch of samples to do an active or ELISA control before the formal experiment to confirm that there is no obvious inactivation. Record the filling lot number and freeze-thaw times.