Why is it hard to grow hematopoietic stem cells in vitro?



What does  Stem Cell Therapy require?

Stem cell therapy involves transporting stem cells into a body to do a specific function and grow into the right type of cells. This is easier said than done. In order to develop a therapy,  several aspects are taken into consideration,

  • Defining what is required
  • Trying to find the stem cell that will do the work
  • The stem cells have to be matched with the recipient 
  • The stem cells have to be placed at the right site
  • The stem cells have to perform the right way

The most successful and widely used stem cell therapy is for Bone marrow cell transplant. Stem cell therapies use Adult Stem You do not have access to view this node  which are used in 

  • Bone marrow cell transplant
  • Peripheral blood stem You do not have access to view this node
  • Umbilical stem cell transplant



How are Leukemia patients treated iwth Stem Cell therapy?

People suffering from Leukemia have a cancer of the white blood cells or leukocytes. Leukocytes are made in the bone marrow and released into the blood where they fight off infections. They are made by the adult multipotent stem cells. When these leukocytes become cancerous they stop fighting infections and interfere with other functions in the body. Doctors in order to treat Leukemia patients have to get the body rid of these abnormal leukocytes. They either use radiation to kill them or chemotherapy and get rid of as many leukocytes as possible. They then inject adult stem cells from a healthy donor whose bone marrow stem cells can be used for the recipient. If the recipient's body accepts these new adult stem You do not have access to view this node,they start to produce new normal healthy leukocytes.



What are the problems with identifying hematopoietic stem cells?

The stem cells that form the blood and immune cells are known as hematopoietic stem cells. They can renew themselves and thus the constant blood production in the body. To study these hematopoietic stem cells scientists have to isolate them and this is where the major problem arises.  These cells look morphologically like the rest of the cells and can be identified  only by using  cell surface proteins as  markers. The other problem is it is hard to grow these hematopoietic stem cells in vitro. So it is hard yet to use these in stem cell replacement therapy.  

But recently researchers at the University of California, Santa Cruz, have found a molecule that can help them establish the blood stem cells in the bone marrow. This can help success rates go up with bone marrow transplants. The molecule identified as Robo4 is only found in the hematopoietic stem cells and endothelial blood cells in the blood vessels. This was studies by Camilla Forsberg and her team. They think that Robo4 acts as an adhesion molecule for the cells of  the bone marrow. The hematopoietic stem cells need the bone marrow environment to grow which cannot be duplicated in a petri dish.  The knowledge of how the Robo4 molecule works in getting the stem cells to adhere at the bone marrow site can help them block the molecule and mobilize the hematopoietic stem cells to enter the blood more efficiently and could help them create the environment in a laboratory to grow the stem cells artificially. Along with Robo4 there seems to be another molecule Cxcr4 which helps in the adhesion of the hematopoietic stem cells  but they seem to work in different mechanisms. Therefore inhibiting these two molecules could help scientists mobilize the cells and make them easier to extract them for stem cell therapy in bone marrow transplants.


To read more on stem cells, click on the links below: