Fiber-Infused Ink Allows 3D-Printed Heart Muscle To Beat

Illustration from Anatomy & Physiology, Connexions Web site., Jun 19, 2013.
Illustration from Anatomy & Physiology, Connexions Web site., Jun 19, 2013.

What makes a body’s organs into what they are is more than just a grouping of specialized cells. They also need to be oriented and attached to each other and scaffolding in order to create structures which can effectively perform the desired function. A good example here is the heart, which requires a large number of muscle cells to contract in unison in order for the heart component (like a ventricle) to effectively pump blood. This complication is what has so far complicated efforts to 3D print complex tissues and entire organs, but recently researchers have demonstrated a way to 3D print heart muscle which can contract when stimulated similarly to a human heart’s ventricle.

At the center of this technique lies a hydrogel that is infused with gelatin fibers. Using a previously developed Rotary Jet-Spinning technology that was reported on in 2016, a sheet of spun fibers was produced that were then cut up into micrometer-sized fibers which were dispersed into the hydrogel. After printing the desired structure – taking into account the fiber alignment – it was found that the cardiomyocytes (the cells responsible for carrying the contractile signal in the heart muscle) align along the thus laid out pattern, ultimately creating a cardiac muscle capable of organized contraction.

These findings come after many years of research into the topic, with e.g. Zihan Wang and colleagues in a 2021 paper reporting on the challenges remaining with 3D printing cardiac tissue, yet also the massive opportunities that this could provide. Although entire heart replacements (via therapeutic cloning with the patient’s own cells) might become possible too, more immediate applications would involve replacements for damaged cardiac muscle and other large structures of the heart.

Printing Organs With A 3D Printer

[Jordan Miller], [Christopher Chen], and a whole bunch of other researchers at the department of bioengineering at U Penn have figured out a way to print 3D tissues using a 3D printer. In this case, a RepRap modified to print sugar.

Traditional means of constructing living 3D tissues face a problem – in a living body, there’s a whole bunch of vasculature sending Oxygen and nutrients to the interior cells. In vitro, these nutrients can’t get to the cells in the core of a mass of tissue. [Jordan], [Chris], et al. solved this problem by printing a three-dimensional sugar lattice. After encasing this lattice in a gel embedded with living cells, the sugar can be dissolved and the nutrients pumped through the now hollow capillaries in the gel.

If you have access to Nature, the full text article is available here. There’s also a great video showing off this technique after the break.

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