Artificial Organs


An artificial organ is an engineered device or tissue that is implanted or integrated into a human interfacing with living tissue to replace a natural organ, to duplicate or augment a specific function or functions so the patient may return to a normal life as soon as possible.  The replaced function does not have to be related to life support, but it often is. For example, replacement bones and joints, such as those found in hip replacements, could also be considered artificial organs.

Implied by definition, is that the device must not be continuously tethered to a stationary power supply or other stationary resources such as filters or chemical processing units. (Periodic rapid recharging of batteries, refilling of chemicals, and/or cleaning/replacing of filters would exclude a device from being called an artificial organ.).  Thus, a dialysis machine, while a very successful and critically important life support device that almost completely replaces the duties of a kidney, is not an artificial organ.

Lists Of Artificial Organs:
Artificial Limbs:
Artificial arms and legs, or prosthetics, are intended to restore a degree of normal function to amputees. 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 one being the simple peg leg. Since then, the development of artificial limbs has progressed rapidly. New plastics and other materials, such as carbon fiber have allowed artificial limbs to become stronger and lighter, limiting the amount of extra energy necessary to operate the limb. Additional materials have allowed artificial limbs to look much more realistic. Prostheses can roughly be categorized as upper- and lower-extremity and can take many shapes and sizes.



Bladder:
The two main methods for replacing bladder function involve either redirecting urine flow or replacing the bladder in situ. Standard methods for replacing the bladder involve fashioning a bladder-like pouch from intestinal tissue. As of 2017 methods to grow bladders using stem cells had been attempted in clinical research but this procedure was not part of medicine.

Brain:
Neural prostheses are a series of devices that can substitute a motor, sensory or cognitive modality that might have been damaged as a result of an injury or a disease. Neuro stimulators, including deep brain stimulators, send electrical impulses to the brain in order to treat neurological and movement disorders, including Parkinson's disease, epilepsy, treatment resistant depression, and other conditions such as urinary incontinence. Rather than replacing existing neural networks to restore function, these devices often serve by disrupting the output of existing malfunctioning nerve centers to eliminate symptoms.



Corpora Cavernosa:

To treat erectile dysfunction, both corpora cavernosa can be irreversibly surgically replaced with manually inflatable penile implants. This is a drastic therapeutic surgery meant only for men who suffer from complete impotence who have resisted all other treatment approaches. An implanted pump in the (groin) or (scrotum) can be manipulated by hand to fill these artificial cylinders, normally sized to be direct replacements for the natural corpora cavernosa, from an implanted reservoir in order to achieve an erection.

Ear:

In cases when a person is profoundly deaf or severely hard of hearing in both ears, a cochlear implant may be surgically implanted. Cochlear implants bypass most of the peripheral auditory system to provide a sense of sound via a microphone and some electronics that reside outside the skin, generally behind the ear. The external components transmit a signal to an array of electrodes placed in the cochlea, which in turn stimulates the cochlear nerve.

 

Eye:


The most successful function-replacing artificial eye so far is actually an external miniature digital camera with a remote unidirectional electronic interface implanted on the retina, optic nerve, or other related locations inside the brain. The present state of the art yields only partial functionality, such as recognizing levels of brightness, swatches of color, and/or basic geometric shapes, proving the concept's potential.  Various researchers have demonstrated that the retina performs strategic image preprocessing for the brain. The problem of creating a completely functional artificial electronic eye is even more complex. Advances towards tackling the complexity of the artificial connection to the retina, optic nerve, or related brain areas, combined with ongoing advances in computer science, are expected to dramatically improve the performance of this technology.



Heart:


Cardiovascular related artificial organs are implanted in cases where the heart, its valves, or another part of the circulatory system is in disorder. The artificial heart is typically used to bridge the time to heart transplantation, or to permanently replace the heart in case heart transplantation is impossible. Artificial pacemakers represent another cardiovascular device that can be implanted to either intermittently augment (defibrillator mode), continuously augment, or completely bypass the natural living cardiac pacemaker as needed. Ventricular assist devices are another alternative, acting as mechanical circulatory devices that partially or completely replace the function of a failing heart, without the removal of the heart itself. Besides these, lab-grown hearts and 3D bioprinted hearts are also being researched. Currently, scientists are limited in their ability to grow and print hearts due to difficulties in getting blood vessels and lab-made tissues to function cohesively.

Liver:

HepaLife is developing a bio artificial liver device intended for the treatment of liver failure using stem cells. The artificial liver is designed to serve as a supportive device, either allowing the liver to regenerate upon failure, or to bridge the patient's liver functions until transplant is available. It is only made possible by the fact that it uses real liver cells (hepatocytes), and even then, it is not a permanent substitute. Researchers from Japan found that a mixture of human liver precursor cells (differentiated from human induced pluripotent stem cells [iPSCs]) and two other cell types can spontaneously form three-dimensional structures dubbed “liver buds.”


Lungs:

With some almost fully functional, artificial lungs promise to be a great success in the near future. An Ann Arbor company MC3 is currently working on this type of medical device. Extracorporeal membrane oxygenation (ECMO) can be used to take significant load off of the native lung tissue and heart. In ECMO, a one or more catheters are placed into the patient and a pump is used to flow blood over hollow membrane fibers, which exchange oxygen and carbon dioxide with the blood. Similar to ECMO, Extracorporeal CO2 Removal (ECCO2R) has a similar set-up, but mainly benefits the patient through carbon dioxide removal, rather than oxygenation, with the goal of allowing the lungs to relax and heal.

Ovaries:

Reproductive age patients who develop cancer often receive chemotherapy or radiation therapy, which damages oocytes and leads to early menopause. An artificial human ovary has been developed at Brown University  with self-assembled microtissues created using novel 3-D petri dish technology. In a study funded and conducted by the NIH in 2017, scientists were successful in printing 3-D ovaries and implanting them in sterile mice. In the future, scientists hope to replicate this in larger animals as well as humans. The artificial ovary will be used for the purpose of in vitro maturation of immature oocytes and the development of a system to study the effect of environmental toxins on folliculogenesis.

Pancreas:

An artificial pancreas is used to substitute endocrine functionality of a healthy pancreas for diabetic and other patients who require it. It can be used to improve insulin replacement therapy until glycemic control is practically normal as evident by the avoidance of the complications of hyperglycemia, and it can also ease the burden of therapy for the insulin-dependent. Approaches include using an insulin pump under closed loop control, developing a bio-artificial pancreas consisting of a biocompatible sheet of encapsulated beta cells, or using gene therapy.


Tissues:


The goal of tissue engineering is to assemble functional constructs that restore, maintain, or improve damaged tissues or whole organs. Artificial skin and cartilage are examples of engineered tissues that have been approved by the FDA; however, currently they have limited use in human patients. Artificial tissues could be produced by using various biofabrication techniques. A predefined pattern for the materials and cells may be obtained.

Thymus:

An implantable machine that performs the function of a thymus does not exist. However, researchers have been able to grow a thymus from reprogrammed fibroblasts. They expressed hope that the approach could one day replace or supplement neonatal thymus transplantation.


Trachea:

The field of artificial tracheas went through a period of high interest and excitement with the work of Paolo Macchiarini at the Karolinska Institute and elsewhere from 2008 to around 2014, with front-page coverage in newspapers and on television. Concerns were raised about his work in 2014 and 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 trachea a hollow tube lined with cells had proved more challenging then originally thought; challenges include the difficult clinical situation of people who present as clinical candidates, who generally have been through multiple procedures already; creating an implant that can become fully developed and integrate with host while withstanding respiratory forces, as well as the rotational and longitudinal movement the trachea undergoes.



Advantages:

The benefits associated with artificial organs have proved that this technology is a new gift of life to ailing patients. Following are some of the pros of using artificial organs.

·   1. Artificial organs can replace diseased or damaged organs, thereby, providing the ailing patient with an opportunity to lead a healthy and normal life.

·      2.  Artificial organs can meet the huge demand of healthy donor organs. There is a huge list of patients who are in urgent need of healthy organs but are unable to find a suitable willing donor.

·      3. A major stumbling block in the form of organ rejection can be solved due to artificial organs. As artificial organs are created by taking the stem cells of the same person and of the same organ, the possibility of rejection has been reduced significantly.

·     4. With the help of regenerative medicine or artificial organ therapy, burn victims can even have a new skin.

·       5. The time taken to create or grow an artificial organ is lesser than waiting period for finding a suitable donor whose organ matches with the recipient's body perfectly.




Disadvantage:

Where the advantages seem credible and truly revolutionary, there are a few negative points or disadvantages that cannot be ignored. 

·      1.  A major concern is the possible presence of the disease in the base tissue which is used to create the organ. Sometimes, even a foreign body tissue is used to regenerate or reconstruct the organ. In such cases, there is a possibility that the tissue is already infected by other diseases.

·      2. The entire cost of growing and transplanting an artificial organ is prohibitive, and thus, limit the scope of its application to the general public.

·       3. There are high chances of organ failure, and the body may even take some time to adapt to the new organ. How the body reacts to the new organ may vary from person to person. If there is a problem with the functioning of the organ, you might need to go for another transplant.

·     4. There are some ethical issues related to artificial organs. There is a possibility that people might misuse the option of an artificial organ. In case of smoking, people may not take the consequences seriously, and go for artificial organ therapy instead of avoiding nicotine. It may also happen that people who can afford this treatment may just opt for it to improve their organ condition and not to save their life.




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