A team of researchers from the University of New South Wales (UNSW) in Sydney developed a new ink made of calcium phosphate and a technique known as ceramic omnidirectional bioprinting in cell-suspensions (Cobics). The process enabled them to print bone-like structures that harden in minutes when placed in water.
While the idea of 3D-printing bone-mimicking structures is not new, Dr Iman Roohani from UNSW said it was the first time such material had been created at room temperature – complete with living cells – and without harsh chemicals or radiation.
“This is a unique technology that can produce structures that closely mimic bone tissue,” he said. “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.”
Making a piece of bone-like material to repair bone tissue has previously involved fabricating the structures in a laboratory using high-temperature furnaces and toxic chemicals, said associate professor Kristopher Kilian, who co-developed the new technology with Dr Roohani.
“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 professor 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 recently in Advanced Functional Materials, the authors described 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 could be suitable for bone tissue engineering applications, disease modelling, drug screening, and in-situ reconstruction of bone and osteochondral defects.
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