How Can We Increase the Biological Complexity of Biomaterials?

Researchers at the New Jersey Center for Biomaterials report on merging the versatility of 3D printing innovative “bioinks” with the biological complexity of decellularized extracellular matrix to build hybrid scaffolds. This approach offers a pathway to future tissue-engineered regenerative implants and organs.

 

Synergistic combinations of fabrication techniques create fascinating new implants and devices. (A) Combining photolithography with solvent casting provides a reinforced neural probe for insertion into brain tissue. (B) 3D printing combined with airbrushing provides a complex scaffold with a gradient of properties. To illustrate this capability the 3D printed scaffold is filled with airbrushed fibers loaded with a red or yellow pigment. Changing the ratio of yellow and red fibers creates a gradient of colours. (C) The combination of porogen leaching and freeze drying provides a bone regeneration sca old with a bi-modal pore distribution. Such scaffolds have been shown to be particularly e ective in regenerating bone. (D) A porous scaffold with hydrogel inserts is used in an attempt to regenerate living teeth. 

3D printing is a cross-disciplinary technology that has stirred excitement from the elementary school classroom to the biomedical device laboratory. The most common method such printers use is fused deposition modelling (FDM) with commodity plastics. FDM can quickly and accurately render complex shapes but, unfortunately, they lack the feature resolution necessary (better than 50 µm) for functional interfaces with cells.

As biomaterials specialists, the NJCBM team is tackling the materials component of 3D-printed implants by developing new bioinks to replace the degradable polymers [poly(lactic acid), PLA and poly(caprolactone), PCL] frequently used in biomedical research. NJCBM’s long history of designing degradable polymers that use only natural building blocks provides an advanced starting point, which is strengthened by the fact that similar polymers are included in several clinically used products.

One of the team’s major thrusts is to functionalize the surfaces of their degradable polymers with both surface charge and chemically reactive groups, often by tethering cell-signaling peptides and proteins. A key example is bone morphogenetic protein 2 (BMP-2), which has been shown to significantly improve bone regeneration.

Working with current 3D technology’s limited resolution, the team has begun a hybrid approach. They have created a reinforcing 3D structure built in part with their degradable, polymers. They then functionalize the structure with biologically-derived bioinks, the most promising of which is decellularized extracellular matrix (ECM). The tissue-specific ECM provides the ultrafine resolution and bioactivity that are necessary for regeneration. 

 

To read the whole article, please visit http://www.biochemist.org/bio/04001/0016/040010016.pdf