YCN - Research in Spot: Fabrication of Bone‐Like Structures via “COBICS”, Ceramic Omnidirectional Bioprinting in Cell Suspensions by Iman Roohani

The rapid advances in additive manufacturing of bioceramics have enabled generation of high resolution bone-mimicked constructs for bone tissue engineering applications.

Despite the robustness of these techniques in fabrication of porous complex-shaped constructs, prints undergo long postprocessing steps,  for example, to remove organic components that are primarily mixed with the ceramic powder or to solidify the structure via sintering at high temperatures, proceeding to be seeded with cells and implantation in vivo. In collaboration with associate profressor Kilian, we have developed a technique, dubbed as COBICS, that enable omnidirectional printing of ceramic constructs with the same chemistry to native bone mineral at room temperature with living cells without requiring harsh chemicals, radiation or sintering. COBICS uses a chemically cross-linked microhydrogel bath with optimised yield-stress properties that support omnidirectional printing of the ceramic ink in the presence of live cells. Once ink comes in contact with the microgel, nanocrystalization kicks off at the interface between ink and hydrogel which further locks the filament in place.   Since this ink can harden quickly without imposing adverse effect on living cells, COBICS enable to print within a suspension of living cells to achieve complex bone shapes, where the cells integrate to form natural bone tissue. COBICS is capable of printing complex and biologically relevant architecture constructs without the need for sacrificial support materials, on-spot and laborious postprocessing steps. This paves the way to fabrication of autologous graft like structures in laboratory which significantly reduces the risks and drawbacks involved in harvesting these grafts from the patient in clinical setting by using only cells from the patient or other sources of regenerative cells. This could also enable patient specific real-time bone reconstruction where the bioprinter could directly print new bone into the resected space. You could even isolate the patients stem cells prior to surgery for inclusion with the ink to improve integration of the new bone into the surgery site or in dental reconstruction. In another example, drugs could be integrated with the ink for sustained release over time to increase natural bone formation, combat bacteria, or influence the immune system (e.g. enhance wound healing).  

Figure 1- A representation of a bone-like structures printed by COBICS technique in a microgel bath containing stem cells (https://doi.org/10.1002/adfm.202008216, Romanazzo et al, Advanced functional Materials 2021 copy-right blongs to Wiley‐VCH GmbH).

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