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Arthur T Knackerbracket has found the following story:

Bioengineers study the development of organ-specific tissues in the lab for therapeutic applications. However, the process is highly challenging, since it requires the fabrication and maintenance of dense cellular constructs composed of approximately 10⁸ cell/mL. Research teams have used organ building blocks (OBBs) composed of patient-specific-induced pluripotent stem cell (iPSC)-derived organoids as a pathway to achieve the requisite cell density, microarchitecture and tissue function. However, OBBs hitherto remain to be assembled into 3-D tissue constructs. In a recent report, Mark A. Skylar-Scott and an interdisciplinary research team at the Wyss Institute for Biologically Inspired Engineering and the John A. Paulson School of Engineering and Applied Sciences at Harvard University, developed a new biomanufacturing method.

Instead of 3-D printing constructs to fill in with tissue (SWIFT). As an example, they engineered a perfusable cardiac tissue to fuse and beat synchronously across a timeframe of seven days. The SWIFT biomanufacturing method allowed the rapid assembly of patient- and organ-specific tissues at therapeutic scales. The research work is now published in Science Advances.

Bioengineering whole organs for therapeutic applications is a daunting task since billions of cells are required for rapid organization into functional microarchitectures, with nutrient supplements via vascular channels. Recent advances in tissue engineering have led to the self-assembly of cerebral, kidney^[$] and cardiac organoids^[$], with several characteristics similar to their in vivo organ counterparts. Scientists build such organoids by generating embryoid bodies (EBs) made of iPSCs (induced pluripotent stem cells) within microwells, cultured under static conditions to differentiate into 'mini organs' of interest. Such organs serve as ideal organ building blocks (OBBs) to biomanufacture tissues of interest with the desired cell density, character, microarchitecture and function.

Researchers can then introduce a perfusable network of vascular channels into the engineered living matrices using embedded 3-D printing techniques. For example, when research teams introduced a method known as sacrificial ink writing into cellular hydrogels^[$] and silicone matrices^[$], the outcomes resulted in a 3-D network of interconnected channels. By building on this strategy, bioengineers proceeded to develop synthetic and biopolymer matrices^[$] with self-healing, viscoelastic responses for minimal complexity of the patterning protocols to form 3-D architectures. However, researchers had thus far only used this method to construct either acellular or spatially cellular matrices.

In the present work, therefore, Skylar-Scott et al. developed a biomanufacturing protocol that relied on sacrificial writing into functional tissue (SWIFT) composed of a living OBB matrix to generate organ-specific tissues with high cellular density, maturation and desired functionality.

The scientists then demonstrated the function and maturation of the engineered bulk vascularized tissue during long-term perfusion studies.

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