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Isolation of circulating megakaryocytes in man
M J Woods1, C R Landon, B E Wagner
1Department of Medical Physics, University of Sheffield, UK.
Abstract:
Recovery of the small numbers of megakaryocytes (MKs) known to be present in normal blood is difficult because of their low frequency. Isolation of circulating MKs was achieved using a modified filtration system in which untreated blood was passed through 5 microns polycarbonate membranes. MKs were retained while most other blood cells passed through the membranes. Four groups of MKs were identified in May Grünwald-Giemsa stained filters of blood from peripheral, central and umbilical veins and umbilical arteries. Type 1 MKs were nuclei with no visible cytoplasm. Types 2, 3 and 4 were nuclei with increasing amounts of cytoplasm. Type 4 MKs, possessing copious cytoplasm, were rarely isolated from peripheral venous blood but were more regularly encountered in central venous and cord blood. Filtration of whole blood through polycarbonate membranes is a useful technique for the isolation of circulating MKs, which are a normal physiological occurrence. Their presence is consistent with the production of platelets in the placenta during intra-uterine life, and subsequently in the pulmonary circulation.
Insights
Researchers developed a filtration method to isolate circulating megakaryocytes (MKs) from blood. This technique successfully identified MKs in various blood vessels, aiding in understanding platelet production.
Area of Science:
- Hematology
- Cell Biology
- Physiology
Background:
- Megakaryocytes (MKs) are crucial for platelet production but are present in low numbers in normal blood, making their isolation challenging.
- Understanding the distribution and characteristics of circulating MKs is important for comprehending platelet biogenesis and related physiological processes.
Purpose of the Study:
- To develop and validate a filtration method for the efficient isolation of circulating megakaryocytes (MKs) from blood.
- To characterize the different types of MKs found in peripheral, central, and umbilical blood vessels.
Main Methods:
- A modified filtration system using 5-micron polycarbonate membranes was employed to isolate MKs from whole blood.
- Blood samples from peripheral veins, central veins, and umbilical arteries/veins were processed through the filtration system.
- Isolated MKs were identified and classified into four types based on the presence and amount of visible cytoplasm using May Grünwald-Giemsa staining.
Main Results:
- The filtration technique successfully retained MKs while allowing most other blood cells to pass through.
- Four distinct types of MKs were identified, categorized by increasing cytoplasmic volume (Type 1 to Type 4).
- Type 4 MKs, with abundant cytoplasm, were more frequently found in central venous and umbilical cord blood compared to peripheral venous blood.
Conclusions:
- Filtration through polycarbonate membranes is an effective method for isolating circulating megakaryocytes (MKs).
- The presence and types of MKs observed support the hypothesis of platelet production occurring in the placenta during fetal development and subsequently in the pulmonary circulation.
- This technique provides a valuable tool for studying circulating MKs as a normal physiological component of blood.