distribution of cells can be achieved. Soft tissues such as skin or
muscle have been engineered by using hydrogels [9].
On the other hand, the regeneration of stiffer tissues, such as
bone and cartilage, has been investigated through the extrusion of
thermoplastic polymers. This class of materials naturally offers
higher mechanical properties compared to hydrogels, even though
the biological cues and the affinity for cells are more limited. To
extrude thermoplastics, either solvents or high temperatures are
needed, and thus cells cannot be included directly into the printing
process. Nevertheless, the mechanical properties have been shown
to be suitable for the regeneration of stiff tissues such as cartilage
and bone. In particular, it was reported that cartilage mechanical
properties could be successfully mimicked by adjusting the fiber
deposition pattern of a molten polymer with a pressure-based
printer [10, 11]. The same machine was used to produce also
composite scaffolds made of a thermoplastic polymer and hydroxyapatite for bone tissue regeneration [12]. Fibroblasts were successfully cultured on scaffolds made of a thermoplastic polymer/
composite material with a filament-based machine [13]. Recently,
a scaffold platform that can actively boost vascularization and may
be applied for extrahepatic islet transplantation was manufactured
with a thermoplastic polymer deposited with a screw-based extrusion machine [14]. The same approach was used to fabricate scaffolds with an in-built radial interconnected porosity gradient, and
cell differentiation assays confirmed the differentiation of hMSCs
toward the osteogenic lineage [15].
Considering the huge potential of extrusion-based printing
shown in literature, here we demonstrate that scaffolds with the
desired geometry, filament diameter, and filament orientation can
be successfully produced by means of the three different
approaches. We show how to determine the right printing parameters for each technique according to the material properties, and
we discuss about the advantages and drawbacks of each approach to
be considered before printing.
2 Materials
1. PolyActive 300PEOT55PBT45 (molecular weight of the initial PEG used for copolymerization, 300 g/mol; block weight
ratio PEOT/PBT, 55/45). The material is kept stored in a
dark and dry place in vacuum-sealed bags prior to use to avoid
contamination and moisture absorption.
2. Differential scanning calorimetry (DSC) pans.
3. Microbalance.
4. DSC apparatus.
78
Andrea Roberto Calore et al.
muscle have been engineered by using hydrogels [9].
On the other hand, the regeneration of stiffer tissues, such as
bone and cartilage, has been investigated through the extrusion of
thermoplastic polymers. This class of materials naturally offers
higher mechanical properties compared to hydrogels, even though
the biological cues and the affinity for cells are more limited. To
extrude thermoplastics, either solvents or high temperatures are
needed, and thus cells cannot be included directly into the printing
process. Nevertheless, the mechanical properties have been shown
to be suitable for the regeneration of stiff tissues such as cartilage
and bone. In particular, it was reported that cartilage mechanical
properties could be successfully mimicked by adjusting the fiber
deposition pattern of a molten polymer with a pressure-based
printer [10, 11]. The same machine was used to produce also
composite scaffolds made of a thermoplastic polymer and hydroxyapatite for bone tissue regeneration [12]. Fibroblasts were successfully cultured on scaffolds made of a thermoplastic polymer/
composite material with a filament-based machine [13]. Recently,
a scaffold platform that can actively boost vascularization and may
be applied for extrahepatic islet transplantation was manufactured
with a thermoplastic polymer deposited with a screw-based extrusion machine [14]. The same approach was used to fabricate scaffolds with an in-built radial interconnected porosity gradient, and
cell differentiation assays confirmed the differentiation of hMSCs
toward the osteogenic lineage [15].
Considering the huge potential of extrusion-based printing
shown in literature, here we demonstrate that scaffolds with the
desired geometry, filament diameter, and filament orientation can
be successfully produced by means of the three different
approaches. We show how to determine the right printing parameters for each technique according to the material properties, and
we discuss about the advantages and drawbacks of each approach to
be considered before printing.
2 Materials
1. PolyActive 300PEOT55PBT45 (molecular weight of the initial PEG used for copolymerization, 300 g/mol; block weight
ratio PEOT/PBT, 55/45). The material is kept stored in a
dark and dry place in vacuum-sealed bags prior to use to avoid
contamination and moisture absorption.
2. Differential scanning calorimetry (DSC) pans.
3. Microbalance.
4. DSC apparatus.
78
Andrea Roberto Calore et al.