May 12, 2015
New research from the University of Illinois holds promise for the treatment of vascular diseases, but it also has drawn some unexpected attention from a community of scientists who may not typically follow the latest developments in biomedicine.
Vascular diseases affect millions around the world. Diabetics and patients who experience problems such as blood flow blockages often experience discomfort and may even face amputations of their limbs. When a person’s body tissues are starved of oxygen and other nutrients, the tissue begins to decay, said Hyunjoon Kong, an associate professor of chemical and biomolecular engineering whose research revolves around nanobiomaterials for cell and tissue engineering.
“In order to solve this problem, we have been trying to recreate a microvascular system in the tissue. But the problem is the limited capability of guiding growth direction and spacing of blood vessels at a physiologically relevant, sub-micrometer length scale,” Kong said.
Researchers have often suggested that spatial organization of proteins that can stimulate blood vessel formation in a 3D matrix would resolve this challenge, because cells would build the vessels following the protein pattern; however, a tool to pattern the protein-releasing microparticles in a 3D matrix was lacking.
However, after reading about moraines, which are accumulations of rock and soil formed by shear tension of advancing or receding glaciers, Kong and his fellow researchers wondered if they would be able to translate the geological phenomena to their work.
The group, which included scientists with a range of backgrounds from chemical engineering to bioengineering and kinesiology, focused on a process called uniaxial freeze drying used to introduce hollow microchannels in a matrix by first forming ice columns via uniaxial freezing and secondly sublimating the ice columns. They proposed the uniaxial freeze drying of a hydrogel loaded with vascular drug-releasing microparticles would be able to align the particles with uniaxially formed ice columns, similar to the natural process to the formation of moraines on a riverside. A hydrogel is a soft material formed from cross-linking between polymers dissolved in water, like Jell-O. Then, the subsequent freeze-drying process will remove frozen water via sublimation, so the resulting microchannels similar to a plant’s vascular bundle present the drug-releasing microparticles on their walls.
“During the glacier formation, minerals suspended in water are sheared and stacked on a riverside due to increased shear stress. The hydrogel assembled following the similar mechanism was used to control the growth direction and spacing of vascular even in wounds caused by vascular ligation. The material will be also useful to controlling spatial organization of engineered neural networks and lymphatic vessels,” the authors wrote.
Their research, “Glacier Moraine Formation-Mimicking Colloidal Particle Assembly in Microchanneled , Bioactive Hydrogel for Guided Vascular Network Construction,” is outlined in Advanced Healthcare Materials.
“We were just happy to publish our paper in the journal. I didn’t expect the glacial community to be excited with our paper. I think it’s a cool correlation between nature and the material design,” Kong said.
Both developments could help advance medical procedures that rebuild the vasculature or deliver drugs through the vasculature, according to Kong. Researchers are currently testing the material in treatment of wounds, specifically diabetic patients who have skin ulcers, he said.
“We expect this material to be quite useful to improving the quality of the maintenance of and treatment of diabetic patients,” Kong said.
In addition to Kong, the study’s authors included UI postdoctoral researcher Min Kyung Lee; UI graduate student Max Rich; UI postdoctoral researcher Artem Shkumatov; Jae Hyun Jeong, chemical engineering professor at Soongsil University in South Korea; Marni Boppart, UI kinesiology and community health professor; Rashid Bashir, UI bioengineering professor; Martha Gillette, UI cell and developmental biology professor; and Jonghwi Lee, chemical engineering and materials science professor at Chung-Ang University in South Korea.
A follow-up study in Scientific Reports takes a look at using the process to promote formation of the neural network.