Wisconsin-Madison scientists 3D print arteries to enable real-time blood pressure monitoring 

Researchers from the University of Wisconsin-Madison University (UW-Madison) have 3D printed blood vessels that enable cardiac patients to monitor their blood pressure remotely.  The research team’s implantable tubular structures emit piezoelectric pulses which act to alert patients when their blood pressure is either getting too high or too low. Leveraging the Wisconsin team’s new pressure-powered […]

Rice Researchers 3D Print with Lasers and Sugar to Build Complex Vascular Networks

A team of researchers from Rice University has uncovered a promising strategy to generate vascular networks, one of the most daunting structures in the human body. Using powdered sugar and selective laser sintering, the researchers were able to build large structures from complex, branching, and intricate sugar networks that dissolve to create pathways for blood in lab-grown tissue.

This is the team’s latest effort to build complex vascular networks for engineered tissues to show that they could keep densely packed cells alive for two weeks. The findings of their study—published in the Nature Biomedical Engineering journal—prove that developing new technologies and materials to mimic and recapitulate the complex hierarchical networks of vessels gets them closer to providing oxygen and nutrients to a sufficient number of cells to get a meaningful long-term therapeutic function.

“One of the biggest hurdles to engineering clinically relevant tissues is packing a large tissue structure with hundreds of millions of living cells,” said study lead author Ian Kinstlinger, a bioengineering graduate student at Rice’s Brown School of Engineering. “Delivering enough oxygen and nutrients to all the cells across that large volume of tissue becomes a monumental challenge. Nature solved this problem through the evolution of complex vascular networks, which weave through our tissues and organs in patterns reminiscent of tree limbs. The vessels simultaneously become smaller in thickness but greater in number as they branch away from a central trunk, allowing oxygen and nutrients to be efficiently delivered to cells throughout the body.”

Overcoming the complications of 3D printing vascularization has remained a critical challenge in tissue engineering for decades, as only a handful of 3D printing processes have come close to mimic the in vivo conditions needed to generate blood vessels. Without them, the future of bioprinted organs and tissues for transplantation will remain elusive. Many organs have uniquely intricate vessels, like the kidney, which is highly vascularized and normally receives a fifth of the cardiac output, or the liver, in charge of receiving over 30% of the blood flow from the heart. By far, kidney transplantation is the most common type of organ transplantation worldwide, followed by transplants of the liver, making it crucial for regenerative medicine experts to tackle vascularization.

Ian Kinstlinger with a blood vessel template he 3D printed from powdered sugar (Credit: Jeff Fitlow/Rice University)

In the last few years, extrusion-based 3D printing techniques have been developed for vascular tissue engineering, however, the authors of this study considered that the method presented certain challenges, which led them to use a customized open-source, modified laser cutter to 3D print the sugar templates in the lab of study co-author Jordan Miller, an assistant professor of bioengineering at Rice.

Miller began work on the laser-sintering approach shortly after joining Rice in 2013. The 3D printing process fuses minute grains of powder into solid 3D objects, making possible some complex and detailed structures. In contrast to more common extrusion 3D printing, where melted strands of material are deposited through a nozzle, laser sintering works by gently melting and fusing small regions in a packed bed of dry powder. According to Miller, “both extrusion and laser sintering build 3D shapes one 2D layer at a time, but the laser method enables the generation of structures that would otherwise be prone to collapse if extruded.”

“There are certain architectures—such as overhanging structures, branched networks and multivascular networks—which you really can’t do well with extrusion printing,” said Miller, who demonstrated the concept of sugar templating with a 3D extrusion printer during his postdoctoral studies at the University of Pennsylvania. “Selective laser sintering gives us far more control in all three dimensions, allowing us to easily access complex topologies while still preserving the utility of the sugar material.”

Assistant professor of bioengineering at Rice University, Jordan Miller (Credit: Jeff Fitlow/Rice University)

Generating new 3D printing processes and biomaterials for vascularization is among the top priorities for the researchers at Miller’s Bioengineering Lab at Rice. The lab has a rich history of using sugar to construct vascular network templates. Miller has described in the past how sugar is biocompatible with the human body, structurally strong, and overall, a great material that could be 3D printed in the shape of blood vessel networks. His original inspiration for the project was an intricate dessert, even going as far as suggesting that “the 3D printing process we developed here is like making a very precise creme brulee.”

To make tissues, Kinstlinger chose a special blend of sugars to print the templates and then filled the volume around the printed sugar network with a mixture of cells in a liquid gel. Within minutes, the gel became semisolid and the sugar dissolved and flushed away to leave an open passageway for nutrients and oxygen. Clearly, sugar was a great choice for the team, providing an opportunity to create blood vessel templates because it is durable when dry, and it rapidly dissolves in water without damaging nearby cells.

A sample of blood vessel templates that Rice University bioengineers 3D printed using a special blend of powdered sugars. (Credit: B. Martin/Rice University)

In order to create the treelike vascular architectures in the study, the researchers developed a computational algorithm in collaboration with Nervous System, a design studio that uses computer simulation to make unique art, jewelry, and housewares that are inspired by patterns found in nature. After creating tissues patterned with these computationally generated vascular architectures, the team demonstrated the seeding of endothelial cells inside the channels and focused on studying the survival and function of cells grown in the surrounding tissue, which included rodent liver cells called hepatocytes.

The hepatocyte experiments were conducted in collaboration with the University of Washington (UW)’s bioengineer and study co-author Kelly Stevens, whose research group specializes in studying these delicate cells, which are notoriously difficult to maintain outside the body.

“This method could be used with a much wider range of material cocktails than many other bioprinting technologies. This makes it incredibly versatile,” explained Stevens, an assistant professor of bioengineering in the UW College of Engineering, assistant professor of pathology in the UW School of Medicine and an investigator at the UW Medicine Institute for Stem Cell and Regenerative Medicine.

The results from the study allowed the team to continue their work towards creating translationally relevant engineered tissue. Using sugar as a special ingredient and selective laser sintering techniques could help advance the field towards mimicking the function of vascular networks in the body, to finally deliver enough oxygen and nutrients to all the cells across a large volume of tissue.

Miller considered that along with the team they were able to prove that “perfusion through 3D vascular networks allows us to sustain these large liverlike tissues. While there are still long-standing challenges associated with maintaining hepatocyte function, the ability to both generate large volumes of tissue and sustain the cells in those volumes for sufficient time to assess their function is an exciting step forward.”

The post Rice Researchers 3D Print with Lasers and Sugar to Build Complex Vascular Networks appeared first on 3DPrint.com | The Voice of 3D Printing / Additive Manufacturing.

Rice university researchers develop sweet new way of 3D printing vascular networks 

Researchers from Rice University have developed a new method of using 3D printing to create artificial vascular networks from powdered sugar.  Replacing traditional production methods with Selective Laser Sintering (SLS) 3D printing, the team created sacrificial templates made from laser-sintered carbohydrate powders. These sugar-based constructs enable cell-laden hydrogels to be patterned with dendritic vessel networks, […]

Texas A&M researchers use 3D printed biomaterials to create facial bone grafts

Researchers from Texas A&M University have combined 3D printing, biomaterial engineering and stem cell biology to create new, more efficient, customizable bone grafting materials. Leveraging these three technologies, the scientists produced 3D printed highly-osteogenic scaffolds that not only facilitate bone cell growth but also serve as a sturdy platform for bone regeneration in custom shapes. […]

The right 3D printed lattice can stop a bullet in its path

3D printing has turned another, previously theoretical, structure into a solid object, and this time it is capable of deflecting bullets. Inspired by the structure of tubulanes, first predicted in 1993, a team of researchers at Rice University have managed to create lightweight materials with high ballistic impact resistance and load‐bearing capabilities “regarded as,” the […]

Nervous System Works with Rice University Researchers 3D Printing Vascular Networks

Nervous System has been heavily engaged in experimenting with 3D and 4D printing of textiles in the past years, and all their research is paying off now as they find themselves engaged in the realm of tissue engineering. The Somerville, MA company is known for their generative design process, combining both programming and art within most of their serious projects, drawing bioengineers from Rice University to turn to them for added expertise.

Assistant professor Jordan Miller invited the Nervous System team to join his researchers on an incredible journey to fabricate examples of possible vascular networks via bioprinting—harnessing their knowledge of software and materials to find a way to create soft hydrogels. Kind of not a phantom but more a path towards ideas that can lead to concepts that may let us build true vascularized structures at one point. As Miller explains, in their research they were able to create large tissue blocks easily, but as so many scientists engaged in bioprinting today have discovered before them, it is extremely challenging to keep cells alive. Viability becomes the goal, and as that becomes more comprehensively mastered overall in bioprinting, it may finally unlock the door to true fabrication of organs that can be transplanted into the human body.

Open-source technology, mainly centered around 3D printing has offered huge opportunity for the bioengineers from Rice University to make progress in their work—and that was what drew them to Nervous System in the first place. Jordan became ‘captivated’ with the structures they were creating, specifically in their Growing Objects series, which was featured as an exhibit at the Simons Center for Geometry and Physics in Stonybrook, NY in August and September of 2014. In speaking with Nervous System, his proposal involved what they describe as an ‘epic task,’ to create simulated synthetic tissue and human organs.

Rendering showing lung-mimicking structures generated within different volumes

“The idea of taking our generative systems which are inspired by nature and using them to actually make living things was a dream come true,” states the Nervous System team in their case study.

Elsewhere the research did,

“…show that natural and synthetic food dyes can be used as photoabsorbers that enable stereolithographic production of hydrogels containing intricate and functional vascular architectures. Using this approach, they demonstrate functional vascular topologies for studies of fluid mixers, valves, intervascular transport, nutrient delivery, and host engraftment.”

As Miller and his expanding team continued to work on developing the necessary tools for bioengineering, part of their research resulted in a new 3D printing workflow called SLATE (stereolithography apparatus for tissue engineering). Their proprietary hardware can bioprint cells encased in soft gels that act just like vascular networks. Nervous System accompanied them (going back as far as 2016) in this bioprinting evolution by designing the materials for the networks—but with their background in programming, the contribution went far beyond designed materials and included customized software for creating ‘entangled vessel networks.’ These networks can be connected to both inlets and outlets for oxygen and blood flow, as they use specific algorithms to ‘grow’ the branching airways.

“Air is pumped into the network and it pools at the bulbous air sacs which crown each tip of the network,” states Nervous System in their case study. “These sacs are rhythmically inflated and deflated by breathing action, so called tidal ventilation because the air flow in human lungs is reminiscent of the flows of the ocean tides.

“Next we grow dual networks of blood vessels that entwine around the airway. One to bring deoxygenated blood in, the other to carry oxygen-loaded blood away. The two networks join at the tips of the airway in a fine mesh of blood vessels which ensheathes the bulbous air sacs. These vessels are only 300 microns wide!”

This project, bringing together scientists and art designers, was featured in the American Association for the Advancement of Science (AAAS) in ‘Multivascular networks and functional intravascular topologies within biocompatible hydrogels,’ authored by Bagrat Grigoryan, Samantha J. Paulsen, Daniel C. Corbett, Daniel W. Sazer, Chelsea L. Fortin, and Alexander J. Zaita.

The recently published article goes into great detail about SLATE 3D printing, indicating that this hardware is capable of rapid bioprinting, and offering possible sustainability to human cells—along with maintaining functionality of stem cells and necessary differentiation.

The project was created by Jordan Miller at Rice University and Kelly Stevens at the University of Washington, and included 13 additional collaborators from Rice, University of Washington, Duke University, and Rowan University.

Nervous System is undeniably one of the most fascinating companies producing 3D printed innovations today. Their versatility has led them to create everything from 4D textiles and 3D printed stretched fabrics to their famed Kinematics Petal Dress. With their latest project delving into 3D printed tissue, the stakes become higher—and their impact on the world much greater. Find out more here.

What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

The Miller Lab fabricated and tested the architectures we generated showing that they can withstand more than 10,000 ventilation cycles while being perfused with human red blood cells. Study of the printed gels shows that the architecture we designed promotes red blood cells mixing and bidirectional flow which is hypothesized to occur in the human lung.

[Source / Images: Nervous System]

Researchers Design Fully Articulated 3D Printed Finger Prosthesis

Silicone cosmetic restoration of middle and ring finger with skin tone match to subject.

Despite the wide range of prosthetics available today, those with partial hand loss are often left out in the cold—and with a disability that often proves to be extremely challenging due to a significant loss of dexterity. Researchers from University of Colorado and Rice University aim to change that with a new design for a finger prosthesis that is fully articulated, featuring a self-contained actuator. The project and subsequent testing are detailed in their recently published paper, ‘Design and evaluation of a distally actuated powered finger prosthesis with self-contained transmission for individuals with partial hand loss.’

Using direct laser metal sintering (DMLS), the research team created a gear transmission for the medial phalanx portion of the finger. The transmission then connects with the DC motor, allowing torque transmission across the PIP joint. This new design features an automated device that is like the index finger size of a female in the 25-50th percentile. While this is an average size, in the future sizing may be possible for other amputees. For proper balance and ‘perception of the prosthesis as an external load worn on the residual limb,’ the scientists designed it with a weight like a human finger.

“The finger phalanges and underactuation mechanism form a six-bar linkage and is essentially a superposition of two four-bar linkages commonly used to underactuate two-phalanx commercial and research devices,” state the researchers. “The linkage system couples the motion of each IP joint to provide a flexion trajectory suitable for a variety of grasps used in ADL.

Testing was centered around evaluating force and flexion of the fingertips, using an Escon 24/2 controller from Maxon Motors powered at 12 V, and a Futek LSB200 load cell powered at 24 V for connecting with the fingertip at varying angles. The researchers also used a Quanser Q8-USB data acquisition board using MATLAB/Simulink to collect the following:

  • Collected load cell force
  • Motor current draw
  • Voltage

In evaluating force of the prosthetic finger, the researchers position the load cell within contact of the fingertip, while the controller powered the motor—driving the finger to the load cell. After that the researchers set up the following steps:

  1. The motor was powered for .5 seconds after detecting the impulse load.
  2. The holding force was recorded.
  3. The load cell was moved to contact the fingertip to measure the flexion speed.
  4. Flexion speed was determined by ‘dividing the time the finger took to contact the load cell from its fully extended position by the angular displacement of the finger.’

The researchers repeated the trials 15 times. As they began evaluating individual gear stages, the team realized further examination would be needed to assess contributions of the face gear pair to transmission efficiency. Mechanics of the fingers will require more validation too, along with further fatigue testing.

Fitting of Vincent finger onto patient. Note location of battery and electrodes on forearm.

 “Ongoing work on the powered finger has resulted in a more compact and higher reduction power transmission and future work will include a closer evaluation of the transmission efficiencies to determine the benefit of using face gears and the changes made to the structure of planetary gear stages,” concluded the researchers. “Alternative gearings that increase the overall reduction of the transmission while decreasing the number of gear stages necessary is of interest, in addition to a more thorough examination of the gear polishing process.

“Work will also include refinements to the residual limb attachment that better accommodates individuals with amputations distal to the MCP, as well as improvements to the robustness and anatomical motion of the kinematic link bar system. Upcoming iterations of the finger will also include improvements to its performance in opposition and safety mechanisms to protect the components in extreme or unexpected loading cases.”

3D printing has earned an honorable niche in the world of prosthetics, undeniably changing the lives of many, from prosthetics that help veterans, to amphibious limbs, to prosthetic breasts for mastectomy patients. What do you think of this news? Let us know your thoughts; join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

Exploded view of medial phalanx gear transmission. Parts outlined in rectangles are the different lamina. Left and right inner laminae contain planetary stages and enclose spur/bevel gear stages housed in the central lamina. Outer laminae connect to proximal phalanx and enclose carrier pieces. Output of gear transmission connects to distal phalanx.

Rendering of the steel components of the powered finger with kinematic link bar system outlined. Dashed lines indicate that the bracket containing the links has been raised to show orientation. Bracket is grounded to proximal phalanx with two set screws at locations indicated by arrows. The hollowed plastic shells that enclose the entire finger mechanism are not shown for clarity.

[Source / Images: Design and evaluation of a distally actuated powered finger prosthesis with self-contained transmission for individuals with partial hand loss]

UMD and Rice take a big step forward for 3D printed human bone

Scientists at Rice University and the University of Maryland (UMD) have outlined a new proof-of-concept for 3D printing artificial bone tissue. With results published in Acta Biomaterialia, the hope is that such tissues may one day help to damage related to arthritis and sporting accidents. Sean Bittner, a third-year bioengineering graduate student at Rice, National Science […]