Artificial organ

• 1. Introduction

  ›

  An artificial organ is a human-made device or tissue designed to be implanted or integrated into the body, interfacing with living tissue to replace a natural organ. The goal is straightforward: let the patient return to a normal life as soon as possible. But that simple premise opens onto a landscape of extraordinary complexity, from hearts that bridge patients to transplant, to ears printed from sheep cartilage, to a thymus grown from reprogrammed cells that the body cannot yet receive.

  One distinction matters immediately. A dialysis machine almost completely replaces the function of a kidney and saves countless lives. Yet it does not qualify as an artificial organ, because it requires the patient to remain tethered to a stationary machine. An artificial organ, by definition, must be free of that continuous connection. It travels with the person.

  What does it actually mean to replace a part of the human body? Which organs have we managed to replicate, which remain out of reach, and what strange new territory opens up when enhancement, not just restoration, enters the picture? Those are the questions driving this documentary.

• 2. From Peg Leg to Electrode

  ›

  Mechanical devices that allow amputees to walk again or continue to use two hands have probably been in use since ancient times. The most notable early example is the simple peg leg. That long history gives artificial limbs a head start over almost every other category of artificial organ.

  New plastics, carbon fiber, and other advanced materials transformed the field. Artificial limbs became stronger and lighter, reducing the extra energy a person must expend to use them. Additional materials allowed limbs to look far more realistic, improving the psychological dimension of recovery alongside the functional one.

  The most significant recent advance, though, is integration. Electrodes can now be placed directly into nervous tissue, and the body can be trained to control the prosthesis through that signal. The prosthetic can be directed by the brain via a direct implant or via implants placed in various muscles. This technology has been tested in both animals and humans, representing a genuine crossing of the threshold between device and body.

  Prostheses are categorized broadly as upper- or lower-extremity and come in many shapes and sizes, reflecting the range of amputations people experience. The underlying goal across all of them remains what it always was: restoring a degree of normal function.

• 3. The Heart's Many Substitutes

  ›

  Cardiovascular artificial organs cover a wider range of devices than many listeners might expect. The artificial heart itself is typically used to bridge the time to a heart transplant, or to permanently replace the heart when transplant is impossible.

  Artificial pacemakers represent a distinct category. They can intermittently augment the natural cardiac pacemaker in defibrillator mode, continuously augment it, or completely bypass it as needed. Ventricular assist devices offer yet another path: they partially or completely replace the function of a failing heart without removing the heart itself.

  Scientists are also researching lab-grown hearts and hearts produced through 3D bioprinting. The current limitation is precise: getting blood vessels and lab-made tissues to function cohesively has proved difficult. That single engineering challenge is the wall standing between present research and a printable heart.

  The range of cardiovascular options reflects how central cardiac function is to survival. No other organ system has attracted quite this breadth of parallel engineering approaches, from purely mechanical bridging devices to biological tissue grown outside the body.

• 4. Printing the Body's Parts

  ›

  Thomas Cervantes and colleagues at Massachusetts General Hospital built an artificial ear from sheep cartilage using a 3D printer. Matching the curves and lines of a human ear required multiple rounds of adjustment, modeled with input from a plastic surgeon. The team noted that their technology is now under development for clinical trials, with the scaffold redesigned to match the size of an adult human ear and to preserve aesthetic appearance after implantation.

  The clinical motivation is specific: each year, thousands of children are born with microtia, a congenital deformity where the external ear does not fully develop. A reliable 3D-printed ear could represent a meaningful step in surgical microtia treatment.

  In the domain of reproduction, an artificial human ovary was developed at Brown University using self-assembled microtissues created with 3D petri dish technology. The groundwork for artificial ovary development was laid in the early 1990s. A 2017 study funded and conducted by the NIH succeeded in printing 3D ovaries and implanting them in sterile mice. Researchers are working toward replicating that result in larger animals and eventually in humans.

  At UCLA, also as of 2017, researchers developed an artificial thymus that, while not yet implantable, is capable of performing all the functions of a true thymus. Dr. Gay Crooks of UCLA described the key challenge: creating a consistent and safe supply of cancer-fighting T cells requires controlling a process that deactivates all T cell receptors in the transplanted cells except for the cancer-fighting ones.

• 5. Blood, Liver, and Lung

  ›

  Artificial red blood cells have been in development for roughly sixty years. Interest intensified when the HIV-contaminated-donor blood crisis began. The first artificial red blood cell, made by Chang and Poznanski in 1968, was designed to transport oxygen and carbon dioxide and also fulfilled antioxidant functions.

  Scientists are now working on a newer artificial red blood cell one-fiftieth the size of a human red blood cell. It is made from purified human hemoglobin proteins coated with a synthetic polymer. The coating allows the cell to capture oxygen when blood pH is high and release it when blood pH is low. It also prevents the hemoglobin from reacting with nitric oxide in the bloodstream, which would otherwise cause dangerous constriction of blood vessels. Allan Doctor, MD, stated that the artificial red blood cell can be used by anyone regardless of blood type, because the coating is immune silent.

  HepaLife developed a bioartificial liver device for the treatment of liver failure using stem cells and real liver cells called hepatocytes. The device was intended as a supportive bridge, either allowing a damaged liver to regenerate or sustaining the patient until transplant. HepaLife is no longer active.

  For lungs, extracorporeal membrane oxygenation, or ECMO, uses catheters and a pump to flow blood over hollow membrane fibers that exchange oxygen and carbon dioxide. A related technique, ECCO2R, focuses mainly on carbon dioxide removal, allowing the native lungs to rest and heal. An Ann Arbor company called MC3 has been working on artificial lungs that are described as almost fully functional.

• 6. Sensing, Thinking, Enhancing

  ›

  The most successful function-replacing artificial eye so far is an external miniature digital camera paired with a remote electronic interface implanted on the retina, optic nerve, or related areas inside the brain. The present state of the art yields only partial functionality: recognizing levels of brightness, swatches of color, and basic geometric shapes. That partial success demonstrates the concept while making clear how much distance remains.

  Researchers have shown that the retina performs strategic preprocessing for the brain, which makes the engineering problem of an artificial eye considerably more complex than replacing a passive optical surface.

  In 2013, scientists created a mini brain that developed key neurological components through the early gestational stages of fetal maturation. Neurostimulators, including deep brain stimulators, send electrical impulses to treat conditions including Parkinson's disease, epilepsy, treatment-resistant depression, and urinary incontinence. These devices often work not by replacing neural networks but by disrupting the output of malfunctioning nerve centers.

  The category of enhancement pushes further still. Kevin Warwick carried out a series of experiments extending his nervous system over the internet to control a robotic hand, and achieved the first direct electronic communication between the nervous systems of two humans. Current research also focuses on restoring short-term memory in accident victims and long-term memory in dementia patients. Subcutaneous chips using RFID technology are already implanted for identification and location purposes, occupying a border zone between medical device and enhancement.

• 7. Trachea and the Limits of Excitement

  ›

  Paolo Macchiarini's work on artificial tracheas at the Karolinska Institute and elsewhere ran from 2008 to around 2014 and generated front-page coverage in newspapers and on television. The trachea, a hollow tube lined with cells, seemed within reach.

  Concerns about his work surfaced in 2014. By 2016 he had been fired, and high-level management at Karolinska had been dismissed, including people involved in the Nobel Prize.

  As of 2017, engineering a functional trachea had proved more challenging than originally thought. The difficulties are layered: patients who reach the stage of needing an artificial trachea have typically been through multiple procedures already. The implant must become fully developed and integrate with the host while withstanding respiratory forces and the rotational and longitudinal movement the trachea undergoes during breathing.

  The trachea story is a useful measure of the field's pace. Excitement, institutional prestige, and media attention moved faster than the biology. The gap between a promising result and a safe, repeatable procedure remained wider than anyone publicly acknowledged at the time. That lesson sits alongside the genuine progress in every other section of this documentary, a reminder that the timeline from concept to clinic is never as short as hope suggests.