Deanna earned their PhD in cellular biology from McGill University in 2020 and has a professional background in medical writing. They joined The Scientist's Creative Services team as an assistant science editor in 2022.
Jan 20, 2023 | 6 min read
Scientists may use 3D printing or bioprinting to manufacture scaffolds that mimic the extracellular matrix, which act as templates for tissue regeneration during artificial organ engineering.
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Artificial organs are bioengineered devices or tissues that scientists create and integrate into the human body to replace, duplicate, or augment functional, naturally occurring organs. 1 They pose a solution to organ donor shortages, and can also be used as medical training tools. 2
Based on the materials researchers use to produce them, artificial organs are divided into three main classes. Mechanical artificial organs are made exclusively of inanimate polymers such as plastics and metals; biomechanical organs involve both living materials such as cells and inanimate materials; and biological or bioartificial organs can be made of living cells and biodegradable polymers. 1
In general, organ manufacturing involves architectural predesign, preparation of materials and tools, cell seeding or integration, and tissue maturation. Additionally, tissue or organ engineering requires a scaffold to act as a template for tissue regeneration. 1 Researchers produce scaffolds with techniques such as 3D printing and decellularizing tissue. 1,3 For example, scientists may use 3D printing to manufacture tissue scaffolds that mimic the extracellular matrix. They can create hydrogels and seed various cell types, including stem cells, onto the scaffold, which can be incubated in a bioreactor for cell proliferation and maturation. 1,2 Additionally, researchers are honing 3D bioprinting methods that use cell-encapsulated printing inks called bioink for scaffold generation and seeding. These methods incorporate living cells, along with other biomaterials such as polymers and growth factors prior to printing. 1,2
Decellularized tissue techniques function in a conceptually similar way, but rely on biologically-produced scaffolding. Researchers omit the predesign stage of manufacturing and utilize pre-existing organ architectures that they treat to remove cells while maintaining the extracellular matrix. 1,4
Flow chart illustrating how 3D printing and decellularized tissues are used to make scaffolds for artificial organs." />
Scientists use 3D printing to make scaffolds that mimic the extracellular matrix, such as hydrogels, or rely on pre-existing organ architectures in decellularized tissues. Stem cells and other cell types are seeded onto the scaffold, which can be incubated in a bioreactor for cell proliferation and maturation of different artificial organs.
The ScientistResearchers have long attempted to develop treatment strategies for naturally occurring sensory dysfunctions and injuries of the nervous system. For example, autologous nerve transplantation or nerve grafting has been considered a gold standard reconstruction technique. However, transplanted nerve grafts serve as scaffolds for nerve regeneration, which is a slow biological process. As a result, functional recovery after nerve grafting can be inefficient at replacing or repairing nerve-dependent organ function. 5
Artificial sensory organs are a prosthetic means of sending information to the brain without relying on nerve regeneration. They are roughly classified as visual devices for light, auditory devices for sound, olfactory gustatory devices for taste and flavor, and tactile or feeling devices for physical stimulation such as thermal pain sensation. 5 Typically, they function by electrically stimulating nerves, such as the optic or auditory nerves. Recent clinical progress of such devices includes the artificial retina, cochlear implants such as the implantable bone anchored hearing aid (BAHA), and taste and olfactory sensors. 5,6 Additionally, researchers are developing new types of artificial nerves based on brain–computer interface (BCI) science. 5 One example of this technology is a device that compensates for damaged spinal cord function and controls paralyzed muscle with signals synthesized from the brain and muscle activity of patients. 5
There are many iterations of artificial filtration systems to treat kidney and liver disease. However, external systems such as dialysis machines and other bioartificial supports physically limit patient activity, require adherence to strict dietary and medication regimens, and have high clinical costs. 7,8
Conventionally, renal assistance devices (RADs) are extracorporeal artificial systems that rely on a combination of a conventional hemofilter and a bioreactor. They mimic glomerular filtration and drive essential metabolic, endocrinologic, and immunologic kidney functions. Researchers creating artificial organ devices are preclinically investigating methods to miniaturize and implant RADs. In addition to RADs, scientists develop renal scaffolds for bioartificial kidneys from pig kidneys, discarded human kidneys, or polymers such as collagen, hyaluronic acid, alginate, agarose, chitosan, fibrin, and gelatin. 7
Similarly, artificial livers may be a solution to organ donor shortages for treating end-stage liver failure and an alternative to extracorporeal artificial supports. 8 For example, researchers made artificial “liver-buds” from human induced pluripotent stem cells (iPSCs) in vitro and transplanted them to successfully rescue an animal model of liver failure. 9
Scientists and clinicians can use 3D printing for cardiac surgical planning and creating custom-fit implants. Researchers have also created devices for cardiac tissue maturation that enhance implant viability, such as cardiac-specific extracellular matrices made of animal-derived bioink or decellularized cardiac tissue. 10 Additionally, in proof-of-concept studies, researchers have manufactured cardiac structures such as branched coronary arteries and embryonic hearts with hydrogels. Using computed tomography (CT) and magnetic resonance imaging (MRI) data, they printed hydrated materials such as alginate, collagen, and fibrin to build mechanically robust and complex 3D anatomical cardiac architectures. 11
Artificial eyes, retinal prosthetic devices, and other ocular prosthesis devices are relatively new breakthroughs, enabled by research into optoelectronics and bioinspired engineering. 12,13 These prosthetic devices transduce light into electrical signals using electrodes, which transmit the electrical signals onto retinal tissue, the optic nerve, or the occipital visual cortex in the brain to restore vision, such as helping patients sense motion, locate objects, follow a path, or recognize large writing. 12
Certain types of artificial heart valves can replace damaged or diseased heart valves associated with aging or cardiovascular abnormalities. 14 Heart valve replacement with bioprosthetic or mechanical heart valves is a critical development in treating cardiovascular disease. Although heart disease remains a leading health concern worldwide, the scientific, medical, and surgical discoveries behind mechanical heart valves and bioprosthetic valves have saved countless lives and improved patient outcomes. 15 Scientists engineer mechanical heart valves from synthetic materials, such as titanium and fabric, or construct bioprosthetic valves from pig or cow heart tissue. 14 A mechanical heart valve is typically more durable than a bioprosthetic valve but has a higher risk of blood clots forming on the metal surface. Researchers continue to investigate tissue engineering and synthetic biology tools that improve artificial valve options, such as searching for anticoagulant materials or developing genetically modified organisms with valves that do not induce inflammation after implantation. 15
Table 1. Mechanical heart valves vs bioprosthetic valves 14,15
