Study: potentially life-saving blood stem cells regenerate in artificial bone marrow

  • 10 Jan 2014

A team of biochemists has engineered artificial bone marrow capable of hosting hematopoietic stem cells -- the potentially life-saving cells used in the treatment of leukemia -- for regeneration.

The work was carried out at the KIT Institute of Functional Interfaces (IFG), the Max Planck Institute for Intelligent Systems, Stuttgart and Tübingen University in Germany, where Cornelia Lee-Thedieck led a team in building a scaffold for stem cell regeneration.

Hematopoietic stem cells, which are derived from both blood and bone marrow, are known for their extraordinary regenerative properties -- they can differentiate into a whole series of specialised cells in the body and travel into the blood from the bone marrow. This makes it an excellent treatment for cancers of the blood, including leukemia and lymphoma where underdeveloped white blood cells multiply out of control. In these cases the patient's own supply of hematopoietic cells is destroyed and they are replenished via a bone marrow transplant from a matched donor.

These are not in plentiful supply, so for years artificial bone marrow has been in development to help fill the need -- existing hematopoietic stem cells only replenish and thrive within the complex, porous structure of bone marrow and do not survive without it. If researchers could develop a suitable host, they could continually transplant cells onto that host to regenerate cells and meet demand. "Multiplication of hematopoietic stem cells in vitro with current standard methods is limited and mostly insufficient for clinical applications of these cells," write the team in the journal Biomaterials. "They quickly lose their multipotency in culture because of the fast onset of differentiation. In contrast, HSCs efficiently self-renew in their natural microenvironment (their niche) in the bone marrow."

The team believes it has now created a potentially game-changing host that mimics that niche. They used synthetic polymers to build macroporous hydrogel scaffolds that mimic the spongy texture of bone marrow. Protein building blocks were then introduced, which would encourage introduced stem cells to stick to the scaffold.

They had to introduce a number of other cells which importantly also thrive within bone marrow to exchange nutrients and oxygen.

To test the scaffold, stem cells from bone marrow and umbilical cord blood were introduced. It took a few days, but those from the cord blood began to multiply.

The authors concluded: "Co-culture in the pores of the three-dimensional hydrogel scaffold showed that the positive effect of MSCs on preservation of HSPC stemness was more pronounced in 3D than in standard 2D cell culture systems."

This is not the first time that artificial bone marrow has been attempted, however. Back in 2008 a team from the University of Michigan maintained that it had created a replica that could make red and white blood cells, and within which blood stem cells could replicate and produce B cells (important immune cells). In this instance, scaffolds were made from a transparent polymer using tiny spheres that were then dissolved to create pores the nutrients could pass through. It's unclear for how long the stem cells thrived, and has contacted the team to try and find out how the research has progressed and if the engineered bone marrow has continued to be effective.

If the research is successful going forward, it could mean the beginning of "blood farming", where artificial bone marrow is used to produce red and white blood cells and platelets to be banked for transfusions.