Ex Vivo Expansion of Hematopoietic Stem Cells

Introduction:

Stem cells are specific cellular subsets that could evolve and emerge into specific cells. These are undifferentiated and unspecialized cells with the potential to evolve and transfigure into any cell type as per the body’s needs. These stem cells are, therefore, perceived as the body’s repair system. Whenever a cellular repair is needed, stem cells will immediately be signaled, and the body instigates their transfiguration into the cell needed to support the repair process and expedite healing. Bone cells, blood cells, liver cells, muscle cells, cartilage cells, or any other cell type could be derived from stem cells.

What Are Hematopoietic Stem Cells?

Hematopoietic stem cells (HSC) are a discrete breed of stem cells that could evolve and transfigure into any of the blood cells. It could be a red blood cell, platelet, or white blood cell. All these blood cells have a specific longevity period, following which they expire and are then withdrawn and kicked out from circulation. Once the existing blood cells approach their senescence and expiration stage, hematopoietic stem cells are signaled to counterbalance the blood cell proportions in the blood. As these stem cells could transfigure into any blood cell subtype, they are also quoted as multipotent hematopoietic stem cells. Hematopoietic progenitor cell is another medical denomination for hematopoietic stem cells.

Where in the Body Are Hematopoietic Stem Cells Found?

The prime locations where hematopoietic stem cells reside include:

• Bone marrow (jelly-like tissue that is entrapped and fills within the inner part of long bones).

• Peripheral blood (blood that is coursing and channeling across the body parts).

• Umbilical cord blood (blood entrapped in the umbilical cord, which is a rope-like structure that bridges the baby in the womb with the maternal body).

• Fetal spleen (spleen of unborn developing baby in the womb).

• Fetal liver (liver of unborn baby in the womb).

What Is the Ex Vivo Expansion of Hematopoietic Stem Cells?

Hematopoietic stem cells are being instituted for various therapeutic modalities. Hematopoietic stem cells could be transferred or grafted to facilitate recuperation for certain alarming disease conditions, including blood cancer (cancer emerging in the blood cells), which is called hematopoietic stem cell transplantation or HSC transplantation. This is one of the medical relevancies and implementations of hematopoietic stem cells. The hematopoietic stem cell transplantation market and scope expressed an appreciable growth. The medical applications concerning HSC elicited an upshoot recently, and so do the hematopoietic stem cell requirements and availability. This substantiated and underscored the gravity of enhancing the magnitude and aggregate of hematopoietic stem cells, and for that motive and justification, an ex vivo expansion technique is being instituted.

Ex vivo expansion is the strategy through which hematopoietic stem cells’ potency, functionality, and proportions are upscaled. Ex vivo expansion procedures, as the name points out, are implemented and effectuated in laboratory settings. Through this laboratory intervention, the HSC number could be inflated while upholding and enhancing the functional prospects of HSC. In ex vivo expansion, the HSC is put through certain laboratory treatments with biological molecules. These biological procedures underscore and intensify the cellular potentialities of hematopoietic stem cells. Apart from the hematopoietic stem cell transplantation technique, hematopoietic stem cells are also employed for gene therapy (correction or repair of faults in the genetic makeup).

What Are the Objectives of Ex Vivo Expansion of Hematopoietic Stem Cells?

The ex vivo expansion is employed to subjugate and overpower certain challenges that are encountered with therapeutic strategies where hematopoietic stem cells are being exploited.

• Amplifies the Numerical Proportion of Hematopoietic Stem Cells: Many times, the undersupply and insufficiency of hematopoietic stem cells bring up obstacles and delimit the practical applicabilities. Ex vivo expansion of hematopoietic stem cells amplifies and upscales the numerical of hematopoietic stem cell quantity, thus scarcity or unavailability of HSC could be tackled.

• Potentiates the Attributes of Hematopoietic Stem Cells: Ex vivo expansion of HSC, though executed in laboratories, is designed and mapped out in such a way that the hematopoietic stem cells’ attributes and traits are retained and kept back. Furthermore, it embraces certain procedures that could even reinforce and augment the cellular traits of HSC.

What Are the Procedures Involved in the Ex Vivo Expansion of Hematopoietic Stem Cells?

For ex vivo expansion, the hematopoietic stem cells ought to be extracted and withdrawn from appropriate hematopoietic stem cell source locations in the patient's body. Thus, extracted hematopoietic stem cells are then cultured and put through specific laboratory habitats that enable symmetric cell division (through which stem cell expansion could be achieved numerically) of the hematopoietic stem cells. This symmetric cell division is engineered by employing certain biological molecules, particularly recombinant variants of cytokines and growth factors. The biological molecules that are instituted for ex vivo expansion include the following:

• Stem Cell Factor (SCF): A hematopoietic cytokine that invokes the hematopoietic stem cells’ expansion and survivability.

• Fms-Like Tyrosine Kinase Ligand 3 (FLT3L): These cytokines interact and engage with the hematopoietic stem cells’ FLT3 receptor, thus upscaling their numerical expansion.

• Thrombopoietin (TPO): It aids in keeping the hematopoietic stem cell’s self-renewal attributes.

• Interleukin 3 (IL3) and Interleukin 6: It enhances and augments the activities of the other growth factors that are instituted alongside the ex vivo expansion technique.

These cytokines and growth factors, in collaboration, facilitate and expedite the symmetric cell division. However, differentiation or specialization of the stem cells is not intended to transpire during this procedure; however, at times, some hematopoietic stem cells get specialized ex vivo, thus bringing down the therapeutic gravity of hematopoietic stem cell intervention. All through the ex vivo expansion phase, the hematopoietic stem cells’ self-renewal, and multipotency traits ought to be secured.

Conclusion:

The ex vivo expansion of hematopoietic stem cells marked a breakthrough in the practical applicabilities of hematopoietic stem cells. Through ex vivo expansion, the meager quantity of the hematopoietic stem cells extracted from the patient’s body could be amplified and capacitated to meet the requirement. As the hematopoietic stem cells extracted from the same individual are being employed, the prospect for many of the intricacies that hematopoietic stem cell therapies bring in could be downturned. Thus, ex vivo expansion of hematopoietic stem cells propounds heightened potential for therapeutic success. It is often a hot discussion topic, owing to the meticulous research being carried out concerning the therapeutic pertinence of hematopoietic stem cells.