Blood Collection in Preclinical Safety Assessment

Circulating Blood Volume in Laboratory Animals¹

Managing Blood Collection

To avoid significant disturbance to the normal animal’s physiology, removed blood volumes for single sampling (such as those encountered in routine toxicity studies) should not exceed 15% of TBV. In addition, multiple sampling regimens (e.g., serial blood sampling for PK/TK purposes over 24 hours) should be limited to 20% of TBV¹. A study investigating clinical and hematological effects of four weekly collections from healthy, adult male and female cynomolgus macaques² (7.5% to 17.5% of TBV), concluded that macaques tolerate 15% of TBV under this regimen. However, removal of 17.5% of TBV resulted in increased incidences of adverse effects during the first 24 hours post blood collections. Based on another study¹, single sampling from rats beyond 15% of TBV resulted, at times, in hypovolemic shock when not completed very slowly; while multiple small samples had little to no impact.

Discrepancies in the average blood volumes are common in literature. One alternative frequently recommended is the 1%- limit³ of body weight (estimating the total blood volume as 10% of the body weight) over two weeks. Although this approach may overestimate the blood volume of laboratory animals, it is close to the 15% of TBV recommended maximum bleeding volume.

OUr Approach to Blood Collection

At Altasciences, we have adopted the 1% of body weight limit for blood volumes collected over a 14-day period (single or multiple collections) for consistency and practicality. Altasciences’ Study Direction Group in partnership with IACUC, continue to find ways to minimize the required survival collection volumes beyond the 1% rule by implementing key processes. Here are some examples:

• appropriately trained personnel, acclimation training to the blood collection procedures for higher quality samples and less repeat draws
• confirming the necessity of the desired endpoints (including requested volumes) during the study design phase
• timepoints that would maximize the return (T_max; steady-state; kinetics of the biomarker, etc.)
• reduction of the required volumes for clinical pathology testing using smaller collection tubes (e.g., 0.9 mL blood for coagulation instead of 1.6 mL; 0.5 mL for hematology instead of 1.3 mL)
• multiplexing (e.g., Luminex assays for simultaneous quantification of multiple target analytes in complex sample types)
• terminal draws when warranted; satellite PK/TK groups
• the use of microsampling when appropriate to the study design

In summary, according to Altasciences’ IACUC policy on animal use, the maximum allowed blood collection volume should not exceed 1% of body weight within a 14-day period to avoid hemodynamic impact, hematopoietic consequences, and confounding the data. Volumes exceeding this requirement should be based on strong scientific justification and a detailed plan for additional physiological support and monitoring.

References:

¹Diehl K-H et al: A Good Practice Guide to the Administration of Substances and Removal of Blood, Including Routes and Volumes. Journal of Applied Toxicology. 21, 15-23 (2001)

²Adams C et al: Effects of weekly blood collection in Male and Female Cynomolgus Macaques (Macaca fascicularis). Journal of the American Association for Laboratory Animal Science. 53, 1-8 (2014)

³University of Tennessee Knoxville. IACUC Guidelines for the Removal of Blood from Laboratory Animals

⁴McGuill M et al: Biological Effects of Blood Loss: Implications for Sampling Volumes and Techniques. ILAR Journal, 31, 4, 5-20 (1989)