Glacial Moraines Influence New Techniques in Micro Biomedicine

Posted by on Mar 10, 2015

Spread the News:

A recent piece of biomedical research has drawn extensively from an unexpected source, glacial moraines. Moraines form as glaciers advance across landscapes over hundreds or even thousands of years, pushing rocks and boulders along their way. If you can imagine the pile of snow that accumulates in front of a sled as it rushes down towards the bottom of your favorite sledding hill in winter–the same thing happens as glaciers move downslope during periods of glacial expansion. As glaciers recede, they leave behind those piles of rocky materials, which we call moraines.

A diagram of how glacial Moraines are formed

Glacial moraines are created from the shear tension of the huge moving mass of ice. Moraines that form from the pile of sediment built up in front of the glacier are called terminal moraines, moraines formed from sediment left on the sides are called lateral moraines, and sediments piled together from two glaciers pushing together is called a medial moraine. Source: Wikipedia Commons

This phenomenon caught the attention of researchers at the University of Illinois who have been tackling a challenging biomedical problem. Advances in modern medicine have created an abundance of highly specialized and effective drug therapies to combat an increasing number of conditions. And new forms of biotechnology allow interventions at the cellular and sub-cellular level. As a result, medical technicians and researchers have sought efficacious drug delivery techniques. In simple terms, it is not usually sufficient to simply give the host a pill to swallow, because medical science now seeks to promote processes in highly specific locations. Medicine has been looking for ways to deliver micro-therapies with more precision, by controlling both the speed with which a drug is released and the spatial pattern it takes inside the body.

There have been several proposed solutions to the problem, but none of which have been effective enough to reach widespread commercial success. A common mechanism that has been explored is what are called “microspheres” – microscopic time-release pill capsules. The problem with these is they do not fully control the time release, and once the microspheres release the active ingredient, they no longer control its movement through the body. The solution has been proposed by Dr. Min Kyung Lee, Dr. Jonghwi Lee of the Choong-Ang University (Korea), and others working in the NanoBiomaterials lab headed by Prof. Hyunjoon Kong at the University of Illinois. They suggested the use of what they term a “microparticle-loaded hydrogel” to deliver the microdrug therapy, which in their case was vascular endothelial growth factor (VEGF) that helps stimulate cell growth for regeneration of blood vessels. Their goal is to introduce the VEGF in precise locations at the cellular level in a hydrogel substrate, where it could help repair damaged tissue.

 

An image of the model displaying the hydrogel freezing process

A model demonstrating how freezing the hydrogel orients its contents in the same way as glacial moraine formation. Source: “Glacier Moraine Formation-Mimicking Colloidal Particle Assembly in Microchanneled, Bioactive Hydrogel for Guided Vascular Network Construction”  Adv. Healthcare Mater. 2015, 4, 195–201

 

The problem that they faced was making sure the VEGF was oriented and distributed spatially correctly inside the host. When the VEGF was distributed randomly inside the hydrogel, the therapy was ineffective. This is where glacial moraines play a role, by providing a model of spatial organization. These moraines developed from the shear tension in the ice, a product of the increasing weight of the glacier as it grows. This shear tension drives minerals and sediment trapped inside and next to the glacier outward to its edges, resulting in the pile of soil, rock and debris we think of as a moraine. Dr. Lee realized that the sediment becomes oriented in a very specific way in relation to the movement of the glacier. If they could replicate that behavior inside their hydrogel, they might be able to orient the VEGF the way they wanted inside the host. They found that by freezing the hydrogel with the VEGF inside it, they were able to orient the drug into uniform channels that increased the ability of the host’s blood cells to migrate into the gel, which allowed them to come into contact with the VEGF, in turn helping to grow blood vessels. They conducted these experiments on mice, a well-established model for humans, and had positive results.

 

image displays the difference in cell growth between the VEGF laden micropours hydrogel and the frozen VEGF laden micro channeled hydro gel in a damaged mouse foot

This image displays the difference in cell growth between the VEGF laden micropours hydrol (c2) and the frozen VEGF laden micro channeled hydro gel (c1) in a mouse foot that had a litigated artery. More red indicates more blood cells. Source: “Glacier Moraine Formation-Mimicking Colloidal Particle Assembly in Microchanneled, Bioactive Hydrogel for Guided Vascular Network Construction” Adv. Healthcare Mater. 2015, 4, 195–201

 

The success of the technique is exciting news on many fronts. It is encouraging news for biomedicine, and medicine in general, by moving us closer to new procedures that might promote blood vessel generation in damaged tissues in humans, more quickly than is possible at present. It is good news for micro-drug therapy research and businesses too, by providing evidence that the field is advancing. But mostly, it is a testament to glaciers and the earth itself, by showing us once again that we only strive to do things as perfectly as happen every day by apparent accident in the natural world. The more fully we understand our natural world, the more capable we are of advancing our own technologies.

 

An elevation map of Long Island

Long Island New York is a well-known example of landscapes formed by glacial moraines. Source: a. U.S. Geological Survey Open-File Report 2011–1004

Spread the News:

Leave a Reply

Your email address will not be published. Required fields are marked *


*