Genetic 'switches' could program 3D-printed bone tissue for blood vessel growth
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.
Researchers at Penn State University have developed a method to 3D print spheroids—tiny clusters of living cells—capable of regenerating bone tissue. By introducing specific strands of genetic information into stem cells, the team demonstrated that bioprinting can create cell clusters optimized for bone tissue regeneration. The bioprinted spheroids not only facilitate bone healing but also promote the formation of new blood vessels within the generated tissue.
The study, published in Chemical Engineering Journal, involved experiments on lab samples and mouse models. While bioprinting spheroids have potential applications in drug testing, using them for regenerative medicine is complex. Researchers must create networks of cells with different functions, as every part of the body is composed of various cell types.
The key challenge lies in facilitating vascularization—the formation of new blood vessels in tissue. Without vascularization, bone tissue regeneration cannot be adequately achieved. To address this, the team employed an advanced aspiration-assisted bioprinting technique that precisely positions individual spheroids within a scaffold. This ensures uniform regeneration and enables the creation of scaffolds that can support complex tissue types like bone, lung, or pancreas cells.
The researchers used microRNA molecules as genetic switches. Two specific strands, miR-148b and miR-210, were introduced to the stem cells, which helped spur bone growth and vascularization, respectively. After culturing the cells for a few days, they assembled the cell clusters into spheroids. Different scaffolds were created, containing spheroids transfected with one microRNA strand or a combination of both in an alternating pattern.
The team then allowed the spheroids to culture and differentiate for 28 days before analyzing their genetic markers to observe the effects of each microRNA strand. In mouse models with bone tissue damage, the bioprinted spheroids showed improved tissue regeneration compared to control groups. While untreated mice had a 35% regeneration rate, those treated with the bioprinted spheroids saw 93% coverage, highlighting the potential of this approach to support bone tissue regeneration.
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