Researchers successfully created muscular units using this new technique which may be broadly used in engineering various anisotropic tissues.
One of the biggest limitations in current bioprinting technology is poor shelf availability due to potential complications in the fabrication and storage of bioprinted tissues. Now, scientists from the Zhang lab at Brigham and Women’s Hospital have created a novel technique to construct frozen, cell-laden structures that can be easily stored for later use by combining bioprinting with cryopreservation. Known as “cryobioprinting,” their new approach, introduced in Matter, uses a bioink embedded with cells to print frozen, complex structures.
“Cryobioprinting can give bioprinted tissue an extended shelf life. We showed up to three months of storage, but it could be much longer,” said Y. Shrike Zhang, PhD, senior author of both papers and an associate bioengineer in the Brigham’s Department of Medicine. “And the unique variation, or what we call the vertical 3D cryobioprinting technique we’ve described, may have broad application in tissue engineering, regenerative medicine, drug discovery and personalised therapeutics.”
The process of cryobioprinting involves using a cryoprotected bioink laden with cells to print tissue constructs on a customised freezing plate, which allows for the precise control and stabilisation of temperature. The printed structures are then immediately cryopreserved in a liquid nitrogen tank for later use. Through optimisation and further evaluation of the technique, Zhang and colleagues discovered that the technology could be used to fabricate tissue constructs that may be applicable for implants and tissue products.
To demonstrate the efficacy and practicality of their technology, the researchers embarked on another study, featured in Advanced Materials, to explore how cryobioprinting may be relevant to muscular tissue engineering. As many tissues in the body, including but not limited to muscles and neurons, are anisotropic – meaning that they have properties that are different in different directions – it is crucial to develop bioinks that have strong mechanical properties.
With their cryoprotected bioink, the team successfully developed vertical, 3D structures that imitate the highly complex and delicate tissues found in the human body and demonstrate excellent mechanical performance. The structures created were anisotropic, with microscale pores aligned in the vertical direction. Skeletal myoblasts within the 3D-cryobioprinted hydrogel constructs also exhibited increased cell alignment, spreading, and viability when compared to the same cells in conventional hydrogel constructs. As a proof-of-concept, the team extended their research to create a muscle-tendon unit using myoblasts and fibroblasts, and a muscle-microvascular unit.
Although their findings merely present very nascent technological demonstrations of 3D cryobioprinting and further research will be needed to validate its clinical use, their unique approach represents an important step in developing a single-step method for tissue biofabrication and engineering robust and versatile anisotropic tissues.
“As the field of tissue engineering is growing fast, these fabricated tissue constructs may find a plethora of applications in muscular tissue engineering and beyond,” said Zhang. [APBN]
- Ravanbakhsh et al. (2021). Freeform cell-laden cryobioprinting for shelf-ready tissue fabrication and storage. Matter.
- Luo et al. (2021). Support Bath-Free Vertical Extrusion Cryo(bio)printing for Anisotropic Tissue Manufacturing. Advanced Materials.