Organ Scaffolding

February 8, 2011 by  
Filed under Organ Scaffolding

Within a single lifetime, the science and technology of surgical possibility has moved from ‘cut out non-essential parts and hope for the best’, to growing replicated organs for transplant.

At this time, organ transplant is more or less commonplace, but there are several drawbacks to the current system. First is availability; for every organ that becomes available for transplant (with only a few exceptions by the demise of the original owner) there are literally hundreds if not thousands waiting to receive it. Second, in order to keep the recipient’s own body from destroying the new organ as an invader, they are required to take immuno-suppression and anti-rejection drugs for the rest of their life. These make new disease and infection more likely, as well as having detrimental effects on organs designed to detoxify the body, such as the liver or kidney.

Growing skin or muscle cells is not (relatively speaking) that complicated a task. Layers of cells on the surface of a growth gel. No matter how thickly it is grown, you are basically dealing with a 2 dimensional structure. You cannot simply fold and staple to form a heart or lung.

There have been several approaches used to create the scaffolds. First, there is decellurization of an existing organ. Removing the host cells to leave the collagen/elastin structure on which a cocktail of recipient organ cells and stem cells are injected that will colonize the structure. This method is superior to whole organ transplant because the scaffold is not only buried within the recipients own cells, but collagen and elastin almost never cause reactive processes in a recipient. However, this method also has the problem of requiring a donor, and therefore having a limited supply.

An artificial scaffold must either be biodegradeable or be adult sized upon implantation. If the recipient is a sub-adult, this could be an impractical if not impossible, situation.

Recently, scientists at Geron Corporation were able to extend the telomeres at the end of dna strands that limit the number of times a cell can replicate (known as the Hayflick limit), thereby allowing the use of a patient’s own cells to be part of the replicated organ, (nearly imperative to prevent rejection.)

Some bio-degradable materials being used are PLA (polylactic acid) which breaks down over time into lactic acid, a substance the body produces naturally during exercise; PGA (polyglycolic acid) degrading faster than PLA; and PCL (polycaprolactone) degrading more slowly than PCA. Both of these substances break down into chemicals that the body is used to processing. There is research into various proteic and polysaccharidic materials as a foundation for organ scaffolds, even using different foundations in combination within a single organ to expedite the functionality of the organ.

Shape is not the only issue involved in organ replication. In order to ensure correct function, many organs require changes in their environment during formation. For vascular systems (blood-vessels, heart) it is pressure and electrical pulses; for bone, it is variations in oxygen. Each organ, if not grown in situ, must duplicate as closely as possible, the environment in which they would have originally formed.

These scaffolds have many possible uses. New bones and joints could be grown to replace worn or damaged ones. One of the problems involved with tendon repair is these elastic structures do not have their own blood supply. The introduction of scaffolds in the repair process could induce a temporary blood supply to enhance healing, and well as build the structure that will induce introduced cells to grow into useful tendon. There is also the possibility of introducing long acting drugs, vitamins and/or minerals to aid in healing or prevent infection, within the scaffolding material itself.

Organ scaffolds also help in the study of bio-diseases. Although cancer cells can be cultured in petri dishes, their function and interaction has been hampered by working on a flat surface. By using bacteriophages that have been injected with a metallic gel, then introducing them to the cancer cells; the introduced organisms infiltrate the cancer and cells. Scientists then use a low-grade magnetic field to cause the cells to form a three dimensional structure that would mimic their placement in the body. It was determined that the cells functioned more efficiently and as they would inside the body.

This method might be used in whole or part, to form a non-physical scaffold for organ formation.

Although it may be years or decades before complex organs like the heart can be replicated and used in humans, there has been a successful transplantation of a ‘grown’ trachea to a female patient. Science-fiction is now science-fact.