Custom blood collection: tailoring hematocrit levels for precision research

Why specify O+ donors?

O+ blood is one of the most common blood types, and in many research settings, it’s chosen for its universal plasma compatibility. While it is not the universal donor for red blood cells (which is O-), O+ donors are typically selected in research because they provide a standardised antigen profile with the same Rh factor (D antigen). This helps minimise donor-to-donor variability and ensures that blood-related experiments are conducted under consistent conditions.

For certain research studies, reducing variability is crucial. By focusing on O+ donors, researchers can ensure that the blood used in their studies contains a consistent profile, helping to isolate the impact of specific experimental variables.

The importance of targeting specific hematocrit blood collection ranges

Hematocrit (HCT), the percentage of blood volume made up of red blood cells, has significant physiological implications. Blood viscosity, oxygen transport capacity, and overall circulatory dynamics are all influenced by hematocrit levels.

For this reason, many studies require precise hematocrit levels within certain ranges. In this case, the client needed blood from O+ donors with hematocrit values within the normal range of 41% to 50% for men and 36% to 44% for women, based on standard literature values. These target ranges align with typical human physiological conditions, ensuring the blood samples are representative of what you would expect in real-world conditions.

Maintaining this hematocrit range is critical for studies in areas such as:

• Medical device testing: Devices like blood pumps, artificial hearts, or dialysis machines are tested to understand how they interact with blood. Hematocrit affects the viscosity and flow properties of blood, which in turn influences the design and functionality of these devices.
• Haemocompatibility studies: Any research involving blood-contacting materials needs blood samples with consistent hematocrit levels to assess how blood cells respond to different materials or surfaces.
• Pharmaceutical research: For studies that aim to assess the effects of drugs on blood, maintaining a consistent hematocrit ensures that the sample reflects the behavior of blood under normal physiological conditions.

A case study: Custom hematocrit blood collection protocol

In this particular case, the research team needed red blood cells (RBCs) isolated from whole blood and pooled from mixed-gender O+ donors within a specific hematocrit range.

The Challenge

The customer needed:

• O+ donors with specific hematocrit ranges.
• Red blood cells isolated from whole blood in CPDA tubes.
• The RBCs pooled and packaged with a 50:50 hematocrit ratio in saline using a custom dilution protocol.

The Results

Research Donors successfully sourced the O+ donors with hematocrit values within the required range:

• 41%-50% for men
• 36%-44% for women

We isolated red blood cells from whole blood collected in CPDA (Citrate Phosphate Dextrose Adenine) tubes and pooled them to achieve the target 50:50 hematocrit ratio in saline, as per the client’s exact specifications. By following a custom dilution protocol, we ensured that the final blood product met the client’s unique requirements for their research.

Why this was important

The 50:50 hematocrit in saline mixture was essential for:

• Ensuring the blood’s viscosity and oxygen-carrying capacity matched the client’s experimental conditions.
• Maintaining reproducibility in laboratory settings where precise RBC counts are necessary for calibration and testing.
• Supporting the client’s research into medical devices and drug delivery systems, where even small variations in blood composition could skew results.