This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: An interdisciplinary team of engineers and chemists at Penn State has laid the groundwork for 3D printing spheroids—tiny clusters of living cells—capable of regenerating bone tissue in response to severe trauma or infections. By introducing different strands of genetic information into undifferentiated, commercially sourced stem cells, the team demonstrated that bioprinting, which layers the fundamental building blocks of organ tissue, can create cell clusters optimized to support bone tissue regeneration.
The bioprinted spheroids not only help bone tissue heal but also facilitate the successful formation of new blood vessels within the generated tissue. The team verified the findings, available in Chemical Engineering Journal, through experiments in the lab and in mouse models. Bioprinting spheroids can be used for a host of applications, including creating accurate biological models to test the effects of experimental drugs.
However, co-corresponding author Daniel Hayes, head of the Department of Biomedical Engineering at Penn State, explained that using these cells for regenerative medicine is not a straightforward process. Researchers are tasked with creating networks of cells that can have vastly different functions from a single fundamental baseline. "Everything in your body is made up of a combination of different cell types, meaning we have to find a way of differentiating cells from one another as they mature when forming these tissues," said Hayes, who also holds the Dorothy Foehr Huck and J.
Lloyd Huck Chair in Nanotherapeutics and Regenerative Medicine. "This project is an attempt to build spheroids that could be used to help reconstruct these complex cellular structures." Bioprinting usually involves encapsulating living cells in a scaffold, traditionally a jelly-like material known as a hydrogel. The scaffold essentially acts like a 3D matrix, with the living cells maturing and growing into complex tissues inside.
However, facilitating vascularization—the process of forming new blood vessels in tissue—has proven difficult when using spheroids to generate bone tissue. "Without vascularization, conventional tissue generation techniques cannot adequately regenerate bone," explained co-corresponding author Ibrahim Ozbolat, professor of engineering science and mechanics, biomedical engineering, and neurosurgery and Huck Institutes of the Life Sciences Chair in 3D Bioprinting and Regenerative Medicine. "We need vascularization to support the thick bonds found in bone tissue." Ozbolat said that building tissues requires extremely precise, coordinated cellular networks, meaning it can be hard to organize spheroids in the patterns needed to spur successful tissue generation.
Aspiration-assisted bioprinting is an advanced approach pioneered by Ozbolat and his research team that picks up individual spheroids and places them at specific locations within a scaffold, according to Ozbolat. "We want the spheroids to be the same distance apart so that we have uniform regeneration," Ozbolat explained. "Aspiration-assisted bioprinting allows us to precisely position spheroids in a scaffold, meaning we can control the exact location of these spheroids to print a host of different complex tissue types, including lung or pancreas cells." Using this technique, the team can create scaffolds that not only support natural healing but also help artificially generated tissue integrate more effectively into the body.
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