Bone marrow-on-a-chip developed

Harvard scientists have developed a new organ-on-a-chip device that captures complexity of living bone marrow in the laboratory and could help test new drugs to prevent lethal radiation exposure.
The latest organ-on-a-chip reproduces the structure, functions and cellular make-up of bone marrow, a complex tissue that until now could only be studied intact in living animals, researchers said.
The device, dubbed "bone marrow-on-a-chip," gives scientists a much-needed new tool to test the effects of new drugs and toxic agents on whole bone marrow.
The device could be used to develop safe and effective strategies to prevent or treat radiation's lethal effects on bone marrow without resorting to animal testing.

The bone marrow-on-a-chip could also be used in the future to maintain a cancer patient's own marrow temporarily while he or she underwent marrow-damaging treatments such as radiation therapy or high-dose chemotherapy.
"Bone marrow is an incredibly complex organ that is responsible for producing all of the blood cell types in our body, and our bone marrow chips are able to recapitulate this complexity in its entirety and maintain it in a functional form in vitro," said Don Ingber, senior author of the paper from Wyss Institute for Biologically Inspired Engineering at Harvard University.

Researchers packed dried bone powder into an open, ring-shaped mold the size of a coin battery, and implanted the mold under the skin on the animal's back.

After eight weeks, they surgically removed the disk-shaped bone that had formed in the mold and examined it with a specialised CAT scanner.
The scan showed a honeycomb-like structure that looked identical to natural trabecular bone.
The marrow looked like the real thing as well. When they stained the tissue and examined it under a microscope, the marrow was packed with blood cells, just like marrow from a living mouse.
And when the researchers sorted the bone marrow cells by type and tallied their numbers, the mix of different types of blood and immune cells in the engineered bone marrow was identical to that in a mouse thighbone.

To sustain the engineered bone marrow outside of a living animal, the researchers surgically removed the engineered bone from mice, then placed it in a microfluidic device that mimics the circulation the tissue would experience in the body.
Marrow in the device remained healthy for up to one week. This is long enough, typically, to test the toxicity and effectiveness of a new drug, researchers said.
The research was published in the journal Nature Methods.