Designing Biomaterials for 3D Printing "Walking Molecules"

Northwestern University researchers have discovered a new synthetic biomaterial that can mimic properties of brain tissue. The biomaterial is suitable for three dimensional (3D) printing.

The findings have important implications for tissue engineering and regenerative medicine. Areas of application include treatment for Parkinson's and Alzheimer's disease, as well as spinal cord injury. The new biomaterial is described in a research paper published in Advanced Science.

Inside the biomaterial, “walking molecules” move around and reshuffle, self-assembling to form larger superstructures. The process can be controlled to modify the structure and functions of synthetic tissues, from the nanoscale to the scale of visible features. Bioactive signals, able to interact with cells, can be integrated into the biomaterial.

"Typical biomaterials used in medicine like polymer hydrogels don't have the capabilities to allow molecules to self-assemble and move around within these assemblies," said researcher Tristan Clemons. "This phenomenon is unique to the systems we have developed here."

With the new biomaterial, the researchers have demonstrated that the self-assembled superstructures can enhance neuron growth.

"This is the first example where we've been able to take the phenomenon of molecular reshuffling we reported in 2018 and harness it for an application in regenerative medicine," said lead researcher Samuel I. Stupp, referring to a previous research paper published in Science.

One of the molecules in the new biomaterial mimics a protein in the central nervous system known as brain-derived neurotrophic factor (BDNF). This protein helps neurons survive by promoting synaptic connections and allowing neurons to be more plastic. While BDNF could be a valuable therapy for patients with neurodegenerative diseases and injuries in the spinal cord, it degrades quickly in the body and is expensive to produce. BDNF-like mimetic signals in the biomaterial could open the door to promising alternatives.

The long-term implications of these findings are very intriguing. One day, surgeons could transplant healthy neurons into patients living with neurodegenerative diseases or brain and spinal cord injuries. The healthy neurons could be "grown" in the laboratory from a patient's own cells using the new biomaterial. And they could be transplanted back into the patients.

After this proof of concept with neurons, the researchers plan to work on other areas of regenerative medicine. Simple chemical changes in the biomaterials would allow them to provide signals for a wide range of tissues.

"Cartilage and heart tissue are very difficult to regenerate after injury or heart attacks, and the platform could be used to prepare these tissues in vitro from patient-derived cells," added Stupp. "These tissues could then be transplanted to help restore lost functions. Beyond these interventions, the materials could be used to build organoids to discover therapies or even directly implanted into tissues for regeneration since they are biodegradable."

Designing biomaterials for 3D printing seems to be a promising approach to helping patients with neurodegenerative diseases. And it also seems promising for regenerative medicine at large.