6/18/2012 By William Bowman
Written by By William Bowman
When a long bone such as a femur breaks, it can result in a gap–known as a critical size defect–between the fractured surfaces. Although this gap may be only millimeters wide, it can cause the body to grow fibrous scar tissue instead of regenerating load-bearing bone during the healing process. University of Illinois researchers have developed a novel way to promote cartilage-to-bone regeneration in damaged long bones.
MechSE Professor Iwona Jasiuk and Molecular and Cellular Biology Professor Jo Ann Cameron are working on a model that will predict how to optimally regenerate bone for a patient. The model takes into consideration patient-specific factors such as bone density, geometry, boundary conditions, and dimensions of the wound.
“In order to optimize this process we study what type of cellular activities are taking place as generation starts and continues,” Jasiuk said.
In their study, the researchers used the tarsus, or a small foot bone, of a hardy African Clawed frog, Xenopus laevis, as a model to understand how gaps regenerate in long bones.
Inserting a natural scaffold over the bone gap is a common method used to help bone regeneration by tricking the bone to think it just needs repair. The scaffolds Jasiuk and Cameron use are interlaced structures made of a polymer base. Sometimes their scaffolds can be ceramic, or a combination of bone polymer ceramic. They collaborate with former MechSE Professor Nicholas Fang who builds the scaffolds. Their process is unique because rather than just using a scaffold as a template, they implant a biocompatible scaffold that is soaked with proteins and growth factors in the critical-size defect area between the fractured bones.
Focusing on the characterization and molding of the bone, Jasiuk compares the quality of the original bone with the regenerated bone by analyzing the structure, chemical composition, chemical properties, and extensions.
Cameron focuses on studying the relationship of cells coming from the body to produce bone growth in combination with the growth factors and material elements.
Their results showed that frogs treated with growth factor-loaded scaffolds generate cartilage-to-bone development in the defect area and stop using the scaffold entirely by pushing it aside, while frogs implanted with scaffolds and no growth factors do not grow bone in the defect site.
“It will not only be the cells coming in on the scaffold but there will be other cells coming in from adjacent injured bone to help heal [the bone defect] completely and to help build the new bone,” Cameron said. “We kind of want to tie the material side of it with the biology.”
Ultimately, Cameron and Jasiuk want the scaffold to deliver the growth factors to help produce cartilage-to-bone regeneration to fill the gap and then have the scaffold dissolve when the cartilage pushes it aside.
Jasiuk and Cameron’s research demonstrates the value in using the frog model system for tissue engineering and that scaffolds are a useful delivery mechanism for growth factors. Their next step is to define what happens with the cartilage in cultures in order to advance their model and to identify the characteristics that will build a more effective scaffold.
The researchers’ findings were published in the December 2010 online issue of Tissue Engineering. Other members of their research team include MechSE doctoral student Liang Feng and MS Bioengineering graduate student Deepika Chitturi.