3 Dimensional Printing of Living Cells in Hydrogel Layers

An optimized 3D inkjet printing process is demonstrated for structuring alginate into a tissue-like microvasculature capable of supporting physiological flow rates. Optimizing the reaction at the single-droplet level enables wet hydrogel droplets to be stacked, thus overcoming their natural tendancy to spread and coalesce. Live cells can be patterned using this process and it can be extended to a range of other hydrogels. _Advanced Materials

...Thus, it would take just under 2 hours to print a 1 cm thick tissue precursor graft and just over 5 h 30 to print a 3 cm thick kidney precursor. _Advanced Materials PDF

Swiss scientists are using a special inkjet printer to assemble three dimensional living constructs that resemble living tissues. They are still in the early stages of the research, but are achieving some interesting results.

They are working on a technique that should eventually allow them to “print” living constructs resembling human tissues in which cells can develop and interact in a coordinated and physiological manner. Their research results have recently been published in the scientific journal Advanced Materials.

“We have not yet created tissue, strictly speaking,” explains Professor Jürgen Brügger, head of EPFL’s Microsystems 1 Laboratory. “At this stage, we have essentially studied a way in which to structure biological materials in three dimensions; this research will improve cell culture and then will eventually be used as a base for creating tissues.”

...To make up a coherent whole, the cells need an environment that provides the right kinds of signals that induce very specific behavior in each of the cells – proliferation, migration, differentiation or death. In natural tissues, these signals come from molecules that make up a complex extracellular matrix (ECM). By studying the connections and communications taking place between cells and between cells and ECM molecules, the scientists were able to reconstruct this matrix and thus create a new kind of biological ink.

On a technical level, the researchers from EPFL’s two Microsystems Laboratories – under the leadership of professors Jürgen Brugger and Philippe Renaud – focused on developing a gel that could be used as a base from which the tissue could be constructed, as well as a strategy for printing droplets.

...Even though it will still be quite some time before tissue can be constructed, this technology could lead to very promising applications on the medium term. “ An exiting avenue would be to develop 3D constructs that function like human tissues and could be used as models for testing new drugs,” says Lutolf. “This is not only very interesting in a biological sense, but could also reduce the need for animal testing.” _Physorg

Learning to create life-like 3 dimensional cell cultures for research, and learning to create 3-D lab-made living tissues for replacement, are not quite the same things. But the two lines of research are likely to borrow from and contribute to each other, extensively.

Cross-posted from Al Fin Longevity

Beware the Zombie Nano-Assassin

PopSci
Perhaps the most important difference between life and non-life is the ability of biological cells and organisms to communicate -- and modify their behaviour on the basis of that communication. Cell signaling and organism to organism communication allow for remarkable adaptation to changing circumstances within and around cells and organisms.

University of Pittsburgh researchers are designing artificial life cellular systems that are able to signal, and achieve self-organising behaviours of a complexity not generally attributed to non-biological entities. This project uses a vastly simplified form of "cell signaling" compared to actual biological cells, but it represents the "baby steps" of a human effort to devise useful artificial nano- and micro- systems which display something of the adaptability and "ingenuity" of living systems.

To communicate, a signaling cell will secrete special nanoparticles known as agonists that prompt the target cell to respond by secreting different nanoparticles known as antagonists. When the antagonists reach the original signaling cell, it stops secreting agonists. Once the signaling cell goes silent, the target cell does the same (it was only secreting antagonists in response to the agonists). At that point, the signaling cell knows to start signaling again.

This cycle locks the two into a cycle that can be thought of as a conversation. Engineers can manipulate that conversation by adjusting the nanoparticles themselves, the capsules' permeability, and the number of nanoparticles each one is given.

But how do the microcapsules know where to find each other? That's the neatest trick of all: the Pitt engineers devised a method -- with a tip of the hat to ants -- wherein the capsules leave a chemical trail behind them as they move about. That trail prompts other microcapsules to follow, just as ants follow one another along a perfect trail even though the trail isn't marked. Such an ability to gather, follow, and cooperate could make for highly targeted drug delivery systems or carry out super-precise chemical processes in the lab. _PopSci

Ants, slime moulds, bacterial signaling etc . . . there are many biological parallels to what the U. Pittsburgh researchers are attempting. The difference is that the biological examples are orders of magnitude more complex than the artificial system -- which is only a computer simulation so far.

Such research may lead to utility fog (flocking nano-actuators) or smart dust (flocking nano-computing). Biomedical research will almost certainly use such technology -- once instantiated in real form -- for diagnostic and therapeutic purposes. Military and intelligence agencies will use it for stealth information gathering -- and perhaps for untraceable assassinations.

Once nano-technological tools are given biological-level signaling tools, the variety of tasks for which such hybrid designs could be suited is difficult to overstate. And you will never see it coming, since such very small objects can float on the wind, burrow through "solid objects", or swim through water like a tiny minnow.

These tools can provide narcissistic would-be tyrants with powers far more powerful and selective than any nuclear arsenal.