Ceramic-based ink enables 3D-printed bone tissue

Using a 3D-printer that deploys an ink made up of calcium phosphate, the scientists developed a new technique called ceramic omnidirectional bioprinting in cell-suspensions (COBICS), which enabled them to print bone-like structures that harden in minutes when placed in water.

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3D-printing bone-mimicking structures is not new, but this is the first time such material can be created at room temperature - complete with living cells - and without harsh chemicals or radiation, said Dr Iman Roohani from UNSW's School of Chemistry.

"This is a unique technology that can produce structures that closely mimic bone tissue," he said in a statement. "It could be used in clinical applications where there is a large demand for in situ repair of bone defects such as those caused by trauma, cancer, or where a big chunk of tissue is resected."

Associate Professor Kristopher Kilian, who co-developed the breakthrough technology, said the fact that living cells can be part of the 3D-printed structure, together with its portability, make it a big advance on current technology.

Until now, making a piece of bone-like material to repair bone tissue involves first going into a laboratory to fabricate the structures using high-temperature furnaces and toxic chemicals.

"This produces a dry material that is then brought into a clinical setting or in a laboratory, where they wash it profusely and then add living cells to it," said A/Prof. Kilian.

"The cool thing about our technique is you can just extrude it directly into a place where there are cells, like a cavity in a patient's bone. We can go directly into the bone where there are cells, blood vessels and fat, and print a bone-like structure that already contains living cells, right in that area."

"There are currently no technologies that can do that directly."

In a research paper published in Advanced Functional Materials, the authors describe how they developed the special ink in a microgel matrix with living cells.

"The ink takes advantage of a setting mechanism through the local nanocrystallisation of its components in aqueous environments, converting the inorganic ink to mechanically interlocked bone apatite nanocrystals," said Dr Roohani.

"In other words, it forms a structure that is chemically similar to bone-building blocks. The ink is formulated in such a way that the conversion is quick, non-toxic in a biological environment and it only initiates when ink is exposed to the body fluids, providing an ample working time for the end-user, for example, surgeons."

When the ink is combined with a collagenous substance containing living cells, it enables in-situ fabrication of bone-like tissues which may be suitable for bone tissue engineering applications, disease modelling, drug screening, and in-situ reconstruction of bone and osteochondral defects.

Next steps include performing in vivo tests in animal models to see if the living cells in the bone-like constructs continue to grow after being implanted in existing bone tissue.