What Are Myeloid Cell Lines and How Are They Used?
Learn about myeloid cell lines, the foundational in vitro tools that allow researchers to consistently study the immune system, blood disorders, and new therapies.
The human body’s blood system is a dynamic network responsible for transporting oxygen and fighting infections. To study this system, scientists use cell lines, which are populations of cells that grow continuously in a laboratory setting.
Myeloid cells are a diverse family of blood cells with a broad range of functions. Their laboratory counterparts, known as myeloid cell lines, have become important tools in science, offering a window into the mechanisms of both healthy biological processes and various diseases.
The Myeloid Cell Family in the Body
All blood cells originate from hematopoietic stem cells in the bone marrow through a process called hematopoiesis. These stem cells give rise to two major lineages: the lymphoid line and the myeloid line. The myeloid lineage is responsible for producing a wide array of cells that are a primary component of the innate immune system, the body’s first line of defense against pathogens.
One major group within this family is the granulocytes, which includes neutrophils that engulf bacteria, and eosinophils and basophils that combat parasitic infections and mediate allergic reactions. Another key member is the monocyte, which circulates in the bloodstream before differentiating into macrophages or dendritic cells. Macrophages clear cellular debris, while dendritic cells act as messengers for the adaptive immune system. The myeloid lineage also produces platelets for blood clotting and erythrocytes for oxygen transport.
Defining Myeloid Cell Lines
Myeloid cells in the body have specific lifespans, but myeloid cell lines are adapted to grow and divide indefinitely in a laboratory. These cells are considered “immortalized” because they have bypassed normal cellular aging processes. This feature distinguishes them from primary cells, which are isolated from tissue and have a finite lifespan in culture.
The immortal nature of these lines provides researchers with a consistent and renewable source of biological material. This consistency ensures that results from different experiments are comparable and repeatable.
Myeloid cell lines are derived from cells of the myeloid lineage and often retain the characteristics of their original cell type. For instance, a cell line derived from a monocyte may still be able to engulf particles, allowing scientists to study specific functions like immune responses in a controlled setting.
How Myeloid Cell Lines Are Developed
The creation of a myeloid cell line begins by isolating cells from a biological source, such as a patient with a myeloid malignancy like acute myeloid leukemia (AML). The cancerous cells from these patients are often naturally immortal, simplifying their establishment as a continuous cell line.
The process involves separating the desired cells from a blood or bone marrow sample and placing them in a culture flask with a nutrient-rich medium. This medium is supplemented to support continuous growth.
Once established, the lines are maintained by transferring a small number of cells to a new flask with fresh medium. For long-term storage, myeloid cell lines can be cryopreserved in liquid nitrogen, ensuring their availability for future experiments.
Prominent Myeloid Cell Lines in Research
Researchers have established hundreds of leukemia-lymphoma cell lines, many of which are of myeloid origin. These lines have become workhorses in laboratories, each with unique characteristics. Among the most well-known are HL-60, U937, THP-1, K562, and NB4.
The HL-60 cell line, established from a patient with acute promyelocytic leukemia (APL), can be chemically induced to differentiate into mature myeloid cells. This makes it a valuable model for studying the molecular events governing myeloid cell differentiation. The U937 and THP-1 lines are frequently used to study monocyte and macrophage functions, including inflammation and phagocytosis.
The K562 cell line originated from a patient with chronic myeloid leukemia (CML) and carries the Philadelphia chromosome, a genetic abnormality associated with CML. This makes it a useful tool for investigating the cancer’s mechanisms and screening potential drugs. The NB4 cell line, also from an APL patient, contains the t(15;17) translocation, making it instrumental in studying the disease’s molecular basis and response to treatments.
Advancing Science with Myeloid Cell Lines
Myeloid cell lines have significantly impacted biomedical research by providing a framework for discoveries in biology and medicine. These models are used to dissect the complex processes of hematopoiesis and the cellular pathways that control how myeloid cells develop and function.
In oncology, leukemia cell lines allow researchers to study the genetic and molecular abnormalities that drive cancer development. They also serve as models for screening new drugs and studying drug resistance, a major challenge in cancer treatment.
Beyond cancer, myeloid cell lines are widely used to study the immune system. They provide a platform to explore the mechanisms of inflammation, the response to infection, and the processes of phagocytosis and antigen presentation. The insights gained from these cellular models continue to drive progress toward new diagnostic tools and therapeutic strategies.