Imma Perfetto
Cosmos science journalist
A new method could soon produce personalised blood stem cells to improve transplant outcomes for people with blood diseases, such as leukaemia and bone marrow disorders.
Researchers from Murdoch Children’s Research Institute (MCRI) in Australia have developed a way to turn human cells, like hair, skin, or blood cells, into haematopoietic stem cells.
Making stem cells from a patient’s own cells may one day eliminate the risk of significant illness or death associated with transplanting mismatched donor cells.
In their new study published in Nature Biotechnology, the scientists show the haematopoietic stem cells can be successfully transplanted in mouse models.
Haematopoietic stem cells found within the bone marrow can produce any type of blood cell, from the white blood cells of the immune system to the oxygen-carrying red blood cells, and the platelets responsible for blood clotting.
“The ability to take any cell from a patient, reprogram it into a stem cell and then turn these into specifically matched blood cells for transplantation will have a massive impact on these vulnerable patients’ lives,” says Elizabeth Ng, lead author of the study and Group Leader of the Blood Development Laboratory at MCRI.
“We have developed a workflow that has created transplantable blood stem cells that closely mirror those in the human embryo. Importantly, these human cells can be created at the scale and purity required for clinical use.”
The researchers first unravelled how blood stem cells form in human embryonic development so they could recreate the conditions in a dish in the laboratory.
Their method involves taking human cells and re-programming them using an already well-understood process into pluripotent stem cells – which have the capacity to differentiate into any cell of the body.
The next step, taking pluripotent stem cells and providing the correct environment and signals to make them change into haematopoietic stem cells (and not the myriad other potential cells) had been the difficult part to crack.
“We differentiate those by turning them into structures we call embryoid bodies, which are in suspension in culture,” Ng explained in a science journalists’ news briefing.
“By giving them growth factors … they will differentiate to form endothelium, and this endothelium will then give rise to blood.
“The actual process of taking a pluripotent stem cell and making a blood stem cell takes about 16 days … Now that we understand it, that process can also be streamlined.”
The lab grown stem cells were then cryopreserved, mimicking procedures in human stem cell transplants, before being injected into immune deficient mice. Once inside the mouse they became functional bone marrow at similar levels to umbilical cord haematopoietic stem cell transplants, a proven benchmark of success.
Haematopoietic stem cell transplantation is a dangerous procedure used to treat life-threatening blood diseases by taking healthy cells from a donor and transplanting them into a recipient.
“Mismatched donor immune cells from the transplant can attack the recipient’s own tissues, leading to severe illness or death,” says co-author Andrew Elefanty, Group Leader of the Blood Diseases Laboratory at MCRI.
“Developing personalised, patient-specific blood stem cells will prevent these complications, address donor shortages and, alongside genome editing, help correct underlying causes of blood diseases.”
The team aims to conduct a phase one clinical trial to test the safety of transplanting the lab grown blood cells in humans within 5 years.
