Artificial Organ

An artificial organ is a human-made device or engineered tissue implanted into the body to interact with living tissue and replace, duplicate or augment the functions of a natural organ. Such devices enable patients to regain essential physiological abilities, improve independence or enhance quality of life. Although artificial organs are commonly associated with life-sustaining functions, the concept can also apply to replacements that restore mobility, communication or appearance. Crucially, an artificial organ must operate without permanent attachment to an external power source or continuous dependence on fixed external systems; devices requiring persistent tethering, such as kidney dialysis machines, are therefore excluded from this category.

Purpose and Development

Artificial organs may be used to maintain life while a patient awaits transplantation, as in the case of artificial hearts, or to restore independence and function, as with prosthetic limbs. They may also facilitate social interaction or sensory experience, exemplified by cochlear implants, or contribute to reconstructive outcomes after surgical oncology or trauma. The design, testing and clinical introduction of artificial organs are labour-intensive and costly, typically involving extensive preclinical evaluation in animal models followed by cautious clinical trials often limited to patients with no remaining therapeutic alternatives.

Artificial Limbs

Artificial limbs, or prostheses, are among the oldest artificial organ technologies. Early examples include simple peg legs, while modern designs employ lightweight, durable materials such as carbon fibre and advanced plastics. These materials reduce energy expenditure and can be cosmetically realistic. Prostheses are generally categorised into upper- and lower-extremity devices and vary widely in form. Increasing integration with the nervous system enables more natural control: electrodes implanted in muscles or neural tissue allow amputees to operate prosthetic limbs through voluntary signals, a development explored in both humans and animals.

Bladder Replacement

Bladder dysfunction may be addressed by redirecting urinary flow or reconstructing a bladder-like reservoir from intestinal tissue. Such surgical approaches remain the standard method of treatment. Research into bioengineered bladders using stem cells has shown experimental promise but has not yet become a routine clinical procedure.

Brain and Neural Prostheses

Neural prostheses aim to restore or modulate motor, sensory or cognitive functions impaired by injury or disease. Deep brain stimulation systems deliver targeted electrical impulses to neural centres to alleviate symptoms of conditions such as Parkinson’s disease, epilepsy, treatment-resistant depression or urinary incontinence. Rather than replacing native neural circuits, these technologies typically modulate pathological signalling to restore function. In parallel, laboratory research has demonstrated the possibility of cultivating rudimentary brain structures, although such work remains at early developmental stages.

Corpora Cavernosa Implants

For severe erectile dysfunction unresponsive to other treatments, both corpora cavernosa of the penis can be surgically replaced with inflatable implants. These systems include fluid-filled cylinders and a manually operated pump placed in the groin or scrotum. By transferring fluid from an internal reservoir to the cylinders, the device achieves an erection comparable in form to that produced by natural erectile tissue.

Ear and Auditory Prostheses

In cases of bilateral severe hearing impairment, cochlear implants provide a functional alternative to damaged inner-ear structures. External components capture sound and convert it into electrical signals transmitted to electrode arrays inserted into the cochlea, thereby stimulating the auditory nerve. For external ear loss, craniofacial prostheses may be used. Recent experimental work using three-dimensional printing and cartilage scaffolds has attempted to recreate anatomically realistic external ears, offering potential future solutions for congenital or traumatic conditions such as microtia.

Artificial Eyes

Functional replacement of vision has been explored through electronic retinal and cortical implants. Current devices usually involve an external miniature camera coupled to implanted electrodes on the retina, optic nerve or visual brain regions. Although present systems offer only limited capabilities—for example detecting brightness patterns or simple shapes—the approach demonstrates the feasibility of neural interfacing for visual restoration. Progress depends on improved understanding of retinal preprocessing and advances in neural integration and computational modelling.

Cardiovascular Prostheses

Artificial organs associated with the circulatory system address conditions affecting the heart and major vessels. Artificial hearts may be used as temporary life-support systems until transplantation or as permanent alternatives when transplantation is not possible. Pacemakers and implantable defibrillators intervene electrically to regulate or replace the heart’s natural pacing mechanism. Ventricular assist devices partially or fully support cardiac output without necessitating removal of the patient’s own heart. Alongside these technologies, research into organ culture and three-dimensional bioprinting aims to create biologically active cardiac tissues, though challenges such as vascularisation currently limit their viability.

Liver Support

Bioartificial liver systems, such as those developed by HepaLife, incorporate living hepatocytes to provide temporary metabolic support in cases of liver failure. These devices assist the patient’s own liver during recovery or bridge the interval until transplantation. Because they rely on real liver cells, they cannot yet serve as permanent substitutes.

Lung Support and Replacement

Progress in artificial lung design has accelerated, with near-functional prototypes under development. Extracorporeal membrane oxygenation (ECMO) provides temporary support by circulating blood through a device containing gas-exchange membranes, thereby oxygenating the blood and removing carbon dioxide. A related technique, extracorporeal carbon dioxide removal (ECCO₂R), focuses primarily on carbon-dioxide clearance, enabling reduced strain on the lungs during severe respiratory failure. Research aims to refine portable or implantable artificial lungs capable of long-term use.