Bone marrow tissue functions like a conveyor belt for our bloodstream, pumping out billions of blood cells each day to keep our bodies in healthy, working order. Scientists have now made a promising advance in the effort to recreate this effect with an artificial version, a tool that could be weaponized in the fight against leukemia and other diseases of the blood.

The pursuit of an engineered version of bone marrow tissue has been motivated by a couple of the possibilities it can bring. It would allow scientists to really zero in on the mechanics behind how blood forms, and in turn, it would also open up new pathways when it comes to the development of therapies for blood disease.

But these artificial tissues have remained elusive. In living bone marrow, blood stem cells live in tiny niches before multiplying and developing into the red and white blood cells that slip into the bloodstream. But trying to recreate this effect in the lab has proven problematic, with the blood stem cells unable to multiply and evolve in typical in vitro models.

Now scientists at the University of Basel, University Hospital Basel, and ETH Zurich have made a promising breakthrough. They've engineered an artificial bone marrow niche that overcomes the limitations of previous approaches, at least for a short while.

Their approach begins with a ceramic 3D scaffold made to resemble human bone. This scaffold is then combined with mesenchymal stromal cells from the human body inside a perfusion bioreactor, a device for mixing biological and synthetic materials.

This left the team with a structure that very closely resembled the molecular structure of real bone marrow niches. In putting it to the test, the scientists found that the hematopoietic stem and progenitor cells, two key ingredients in the multiplying and maturation of blood stem cells, remained functional and continued carrying out their work for several days.

With further development, these artificial bone marrow niches might become tuneable testbeds for researching how different factors, like certain proteins, shape blood formation in humans. They could also be used in drug screening to see how certain patients respond to particular treatments.

"We could use bone and bone marrow cells from patients to create an in vitro model of blood diseases such as leukemia, for example," explain study authors Ivan Martin and Timm Schroeder. "Importantly, we could do this in an environment that consists exclusively of human cells and which incorporates conditions tailored to the specific individual."

The research was published in the journal Proceedings of the National Academy of Sciences.

Source: University of Basel

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