PCL-PEG Blends for Tissue Engineering

Sequential Bioprinting with GeSiM Instruments

PCL (PolyCaproLactone) is a popular hard-phase biopolymer for tissue engineering and 3D printing. It is biocompatible and – to a certain extent – biodegradable. Multi-printhead instruments like the GeSiM BS31 easily combine PCL struts with cell friendly alginate/hydrogels.

Hard-phase biopolymers shall be optimized towards a quick degradation/mass loss when getting in contact with body fluid. An inherent drawback of pure PCL is the relatively high stability under physiological conditions. Here we present a recent study [1] addressing this problem. It was conducted using the predecessor of BS3.1, BS2.1.

 

PCL and polyethylene glycol (PEG) blends (PCL-PEG) together with alginate dialdehyde gelatine hydrogel (ADA-GEL) loaded with stromal cell line (ST2) were investigated.

 Scheme of a hard-soft phase scaffold with the hard thermoplastic phase (grey) and the soft hydrogel phase (yellow) containing the cells [1]

Scheme of a hard-soft phase scaffold with the hard thermoplastic phase (grey) and the soft hydrogel phase (yellow) containing the cells [1]

Stereomicroscope images of a plotted PCL-PEG (7030) scaffold as fabricated: topview (a); and side view (b) (scale bar = 2 mm) [1]

Stereomicroscope images of a plotted PCL-PEG (7030) scaffold as fabricated: topview (a); and side view (b) (scale bar = 2 mm) [1]

 

 

 

 

 

 

 

 

 

 

 

The PCL-PEG blends showed a much faster degradation and a mass loss tending to be almost equal with the corresponding content of PEG being ~14% for the PCL-PEG 8020 and ~23% for the PCL-PEG 7030 compositions. The wetting behaviour and the cell behaviour were improved in comparison to pure PCL. Blends showed improved hydrophilicity and cell response with PEG blending increasing the degradation and decreasing the mechanical properties of the scaffolds.

Fluorescence microscope images (a–f) of the actin cytoskeleton (red) and the cell nuclei (green) of ST2 cells in a PCL-PEG ADA-GEL construct after 28 days of incubation of different magnification: (a,b) overview images; (c) densely packed area of the cells covering both materials; (d) cell morphology on the hard phase; (e) cell agglomerate and spread single cells in hydrogel; and (f) densely packed area of cells (hydrogel phase) [1]

Fluorescence microscope images (a–f) of the actin cytoskeleton (red) and the cell nuclei (green) of ST2 cells in a PCL-PEG ADA-GEL construct after 28 days of incubation of different magnification: (a,b) overview images; (c) densely packed area of the cells covering both materials; (d) cell morphology on the hard phase; (e) cell agglomerate and spread single cells in hydrogel; and (f) densely packed area of cells (hydrogel phase) [1]


[1] Tobias Zehnder, Tim Freund, Merve Demir, Rainer Detsch and Aldo R. Boccaccini: Fabrication of Cell-Loaded Two-Phase 3D Constructs for Tissue Engineering, Materials 2016, 9(11), 887