Chinese Researchers Improve 3D Printing PCL Scaffolds with Extrusion-Based Cryogenics

by Bridget O’Neal, 3D Printing

Chinese researchers are investigating the benefits of using biodegradable polymers for bioprinting scaffolds, as outlined in “Fabrication and Characterization of Porous Polycaprolactone Scaffold via Extrusion-based Cryogenic 3D Printing for Tissue Engineering” published in the journal Materials and Design. Researchers used 3D porous Polycaprolactone (PCL) scaffolds with combined extrusion-based cryogenic 3D printing and freeze-drying in an attempt to overcome existing limitations like affordability, lack of efficiency in fabrication and inferior process control.

Tissue engineering is a broad field today and one that is expansive with research and many different goals—most of which end in the ultimate discovery of a way to create sustainable bioprinted organs for transplantation. In creating or regenerating tissue, scientists usually work with scaffolds, living cells and other “bioactive factors.” Structures like scaffolds must be biocompatible, and obviously non-toxic too if they are being implanted into a human patient. PCL is a commonly used polymer in creating scaffolds, suitable due to features like biodegradability, biocompatibility, low melting point, good strength and good solubility.

The researchers observed that extrusion-based cryogenic 3D printing (ECP) is gaining more popularity as a choice for bioprinting because it allows for greater strength in scaffolds, whether they are made of collagen, chitosan, PLGA or other materials. In this study, the authors used ECP to fabricate PCL scaffolds and then study the results.

To ensure success in printing, the researchers relied on several different treatments, including a rough-surfaced glass slide as a collector, adding a transitional path at the corners of the adhesive area and scrubbing slides with ethanol. Porosity was measured, with results showing an increase due to “widening of filament offset.”

In terms of measuring biocompatibility, the researchers found that while cell attachment was “not well promoted” at first, cell proliferation was “effectively facilitated” because of the rough surface and porosity of scaffolds.

“Although more stretched cells were found on the surface of EMP group after seven days, the number of cells on ECP scaffolds were much higher and their morphologies become more stretched as compared to the ones at day three,” the researchers explained. “Thus, it can be concluded that PCL scaffolds fabricated via ECP are highly biocompatible and better support cell adhesion and proliferation as compared to EMP scaffolds.

“Overall, the fabricated PCL scaffold, with such improved structural, physico-chemical and biological features, can be a promising candidate for tissue engineering applications.”