Bioink made from cow cells paves way for scaffold-free 3D printed replacement joints

A research team of engineers has developed a method to create artificial cartilage using 3D printing that may one day allow us to grow replacement patches for worn out joints.

“Our goal is to create tissue that can be used to replace large amounts of worn out tissue or design patches,” said Ibrahim T Ozbolat, associate professor of engineering science and mechanics. “Those who have osteoarthritis in their joints suffer a lot. We need a new alternative treatment for this.”

Cartilage represents a good target for bioprinting due to its simple structure, consisting of only one cell type and with no blood cells in the tissue. Additionally, its inability to repair itself means that the prospect of artificial patches represents an important medical opportunity.

Previous attempts to create cartilage did so by embedding cells in a hydrogel, a substance comprising of polymer chains and water that acts as a scaffold for the tissue’s growth. This method didn’t allow cells to grow as normal, however, meaning that the created tissues lacked sufficient mechanical integrity. Ozbolat’s team’s new method allows them to produce larger scale tissues without the need for a scaffold.

The multiarmed 3D bioprinter used to print the cartilage

The multiarmed 3D bioprinter used to print the cartilage

The method consists initially of creating a tiny tube from algae extract. Cartilage cells taken from cows are then injected into the tube and allowed to grow for about a week and adhere to each other. Because cells do not stick to alginate, the tube can be removed to leave a strand of printable cartilage.

This strand substitutes for ink in the 3D printing process. Using a specially designed prototype nozzle, the 3D printer lays down rows of cartilage strands in a pattern chosen by the researchers. After about half an hour, the cartilage patch self-adheres enough to move to a petri dish containing nutrient media. The nutrient media allows the patch to further integrate into a single piece of tissue.

“We can manufacture the strands in any length we want,” said Ozbolat. “Because there is no scaffolding, the process of printing the cartilage is scalable, so the patches can be made bigger as well. We can mimic real articular cartilage by printing strands vertically and then horizontally to mimic the natural architecture.”

A plug of 3D bioprinted cartilage sits in nutrient media. Images courtesy of Ozbolat, Penn State

A plug of 3D bioprinted cartilage sits in nutrient media. Images courtesy of Ozbolat, Penn State

The cartilage produced by the team is currently inferior to natural cartilage, but better than the cartilage made using hydrogel scaffolding. However, Ozbolat believes mechanical pressure on the artificial cartilage will improve its mechanical properties, mimicking the way in which natural cartilage forms with pressure from the joints.

Applying the process to human cartilage will likely involve each individual treated providing their own source material to avoid tissue rejection.

However, once successful, we will have proven the possibility of artificially repairing tissues, as opposed to our current limitation to replacement or support.

Other tissues are far more complex than cartilage but if we consider it a starting point, this developing method could potentially lead to the ability to create “patches” for a variety of tissues, enabling us to combat the degradation of cells that leads to a variety of medical problems.

The future of 3D printed housing has serious curve appeal

Architectural firm WATG (Wimberly, Allison, Tong & Goo) has won first prize in the Freeform Home Design Challenge, a competition to design the world’s first freeform 3D printed house.

The challenge, commissioned by Branch Technology, invited architects, designers, artists and engineers from around the world to design a 600 to 800 sq ft single-family home that “rethinks traditional architectural aesthetics, ergonomics, construction, building systems, and structure from the ground up”.

Branch Technology was founded by a group of architects and engineers with the intention of liberating design using their patented “Cellular Fabrication” technology.

Cellular Fabrication is a process that uses 3D printed structures as scaffolds and adds conventional materials to form a structure before insulation, and finishes are applied.

Possessing the world’s largest freeform 3D printer, Branch issued the challenge with the notion of sparking an investigation into how 3D printing technologies can improve our built environment and lives today.

Images courtesy of Daniel Caven, WATG Chicago Urban Architecture Studio

Images courtesy of Daniel Caven, WATG Chicago Urban Architecture Studio

Participants were required to propose conceptual solutions for all aspects of the house, from material applications to structure.

The interiors had to include a kitchen, bath, living area and bedroom. Additionally, building systems had to provide resolutions for mechanical, electrical, plumbing and lighting requirements while also allowing for passive solar design strategies.

WATG’s Chicago-based team, consisting of Daniel Caven, Chris Hurst, Miguel Alvarez and Brent Watanabe, won with their ‘Curve Appeal’ design.

The team, part of WATG’s Urban Architecture Studio, designed the house to consist of two main components: an interior core and exterior skin.

The open interior living spaces protect occupants from the elements via passive strategies while connecting them to the exterior spaces. The exterior skin is derived from simple archways that blend with the site.

Speaking of the design, Branch Technology founder, Platt Boyd, said: “Curve Appeal is a very thoughtful approach to the design of our first house.  It responds well to the site conditions, magnifies the possibilities of cellular fabrication and pushes the envelope of what is possible while still utilising more economical methods for conventional building systems integration.”

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WATG’s design seems to fit well with Branch’s design philosophy, which is focused on building structures inspired by the nature.

As opposed to the slow, layer-by-layer process of standard 3D printing, Branch boasts that their “algorithm creates both the geometry and robotic motion to construct complex geometries in open space, without the use of support materials or highly controlled build environments”.

The ‘Curve Appeal’ house is set to begin planning phases in Chattanooga, Tennessee at Branch Technology’s lab and is expected to begin 3D printing in 2017.