Human CD34+ Hematopoietic Stem Cells

The human body is made of multiple systems that depend on each other to maintain balance. Each system is made of functionalized cells that play specific roles in the necessary processes. The immune system defends us against foreign pathogens with the help of differentiated blood cells. Hematopoietic stem cells in the bone marrow are one type of leukocyte that play a significant role in blood cell development. 

What Are Hematopoietic Stem Cells?

CD34+ hematopoietic stem cells, or HSCs, possess a trait termed multipotency, which means they can produce a variety of mature blood cells. HSCs can produce leukocytes, erythrocytes, and platelets.

Hematopoietic stem cells are capable of self-renewal, which means they can regenerate themselves and perpetuate. These cells can differentiate into almost any blood cell they need to, making hematopoietic stem cells an essential piece of the hematopoietic system. For example, to maintain an effective defense against pathogens, the human body produces around 10 million new naive CD4+ T cells each day. Each of those, and the many that did not survive the differentiation process, began as a CD34+ hematopoietic stem cell. 

Hematopoietic Stem Cell Function

The ability of hematopoietic stem cells to develop into so many different types of cells makes them a significant factor in the growth and regeneration of tissue in the body. This type of cell is more common in individuals who have not fully matured. 

In the early stages of development, humans have a larger quantity of stem cells. As the person ages, the stem cells differentiate into more functionalized cell populations. These cells are considered progenitors because they are some of the earliest stages in the development of fully differentiated cells.

While the majority of CD34+ hematopoietic stem cells reside in the bone marrow, they can also be found near vascular tissue and endothelial tissue due to the frequency at which they are needed to regenerate downstream cell types. 

What Are Hematopoietic Stem Cells Used For?

These cells serve many developmental functions within the body, because of this, they are an important cell for scientists to study. Particularly pertaining to blood disorders that result from dysfunctional blood cells, hematopoietic stem cells can be enriched, cultured, and reintroduced into a patient to catalyze recovery. These cells can be used to treat leukemia, myeloma, lymphoma, and even replace cells damaged by chemotherapy. 

CD34+ lymphohematopoietic stem cells are known for their ability to reconstitute blood cells in the hematopoietic system. This property allows CD34+ stem cells to be used in treating humans with ischemic conditions. Ischemia occurs when oxygen and blood flow are restricted in some parts of the body. While the function of CD34 remains unclear, the stem cells they are attached to can be used in transplants to repair and replace damaged blood cells. 

What Is CD34?

Cell markers, or surface antigens, are molecules located on a cell’s membrane that carry out very specific functions that aid the cell in its overall role in the body This role-specific expression allows scientists to use expression of these proteins to identify cells. CD34, or sialomucin, is a single-pass transmembrane protein that is expressed in certain vascular and hematopoietic tissue. The exact function of CD34 is unknown, but it is known to be an adhesion molecule that is involved in trafficking of immune cells to various locations within the body. CD34 is also known as a human hematopoietic progenitor cell antigen and is predominantly used to identify hematopoietic stem cells. While CD34 can also be expressed by other types of cells, and there are stem cells that exist without the CD34 marker, it’s still a fairly accurate way for scientists to locate and target stem cells in the bone marrow. 

CD34 Positive Cells (CD34+)

CD34+ cells have a CD34 protein present on their surface. CD34+ stem cells serve as a reservoir of precursors for all mature human blood cells. CD34- stem cells are much less common and are mainly found in umbilical cord blood. Although these CD34- stem cells have been found to possess potent erythrocyte/megakaryocyte differentiation potential, they are fairly difficult to isolate in sufficient numbers for this application. Blood CD34+ stem cells are relatively rare in the body, and having too many or too few is associated with significant health risks. 

What Is the Importance of CD34 Expression?

CD34 markers are necessary for scientists to both identify and isolate hematopoietic stem cells. Some cell separation methods rely on the physical properties of cells, but others use antibodies to seek out specific antigens on the surface of target cells. The expression of CD34 markers on a cell membrane allows CD34-specific antibodies to find and bind with tohematopoietic stem cell. 

CD34 Cell Isolation

CD34+ cells make up roughly 1-2% of all bone marrow cells. CD34+ cells are typically collected through the process of leukapheresis, whereby blood is processed in a way that concentrates white blood cells and removes many of the red blood cells. Once a concentrated sample containing hematopoietic stem cells is acquired, researchers can apply additional separation methods to extract the desired cell population from the leukopak. Even though leukopaks are specifically designed for further cell separation, harsh isolation methods can result in cell damage that affects viability and cell function. Gentle isolation is especially critical when separating rare or fragile cell populations, such as CD34+ cells,  in order to acquire a sufficient number of cells that retain their normal function.

Using Microbubbles to Enrich CD34+ Cell Samples

Akadeum Life Sciences has developed an innovative cell separation method for isolating human primary cells from concentrated leukocyte samples. The method, called buoyancy activated cell separation (BACSTM), harnesses the natural properties of tiny glass bubbles to perform quick and gentle cell separation. Through the use of different target-specific biotinylated antibodies, our products can isolate a wide variety of cell markers. 

Akadeum is actively seeking partners for projects in human cell isolation. If you think there’s room for commercial or scientific collaboration, partner with us to harness the full potential of our cell separation products. 

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