3D-Printed PCL/PLA Composite Stents: Towards a New Solution to Cardiovascular Problems - PubMed (original) (raw)

3D-Printed PCL/PLA Composite Stents: Towards a New Solution to Cardiovascular Problems

Antonio J Guerra et al. Materials (Basel). 2018.

Abstract

Biodegradable stents (BRS) offer enormous potential but first they must meet five specific requirements: (i) their manufacturing process must be precise; (ii) degradation should have minimal toxicity; (iii) the rate of degradation should match the recovery rate of vascular tissue; (iv) ideally, they should induce rapid endothelialization to restore the functions of vascular tissue, but at the same time reduce the risk of restenosis; and (v) their mechanical behavior should comply with medical requirements, namely, the flexibility required to facilitate placement but also sufficient radial rigidity to support the vessel. Although the first three requirements have been comprehensively studied, the last two have been overlooked. One possible way of addressing these issues would be to fabricate composite stents using materials that have different mechanical, biological, or medical properties, for instance, Polylactide Acid (PLA) or Polycaprolactone (PCL). However, fashioning such stents using the traditional stent manufacturing process known as laser cutting would be impossible. Our work, therefore, aims to produce PCL/PLA composite stents using a novel 3D tubular printer based on Fused Deposition Modelling (FDM). The cell geometry (shape and area) and the materials (PCL and PLA) of the stents were analyzed and correlated with 3T3 cell proliferation, degradation rates, dynamic mechanical and radial expansion tests to determine the best parameters for a stent that will satisfy the five strict BRS requirements. Results proved that the 3D-printing process was highly suitable for producing composite stents (approximately 85⁻95% accuracy). Both PCL and PLA demonstrated their biocompatibility with PCL stents presenting an average cell proliferation of 12.46% and PLA 8.28% after only 3 days. Furthermore, the PCL/PLA composite stents demonstrated their potential in degradation, dynamic mechanical and expansion tests. Moreover, and regardless of the order of the layers, the composite stents showed (virtually) medium levels of degradation rates and mechanical modulus. Radially, they exhibited the virtues of PCL in the expansion step (elasticity) and those of PLA in the recoil step (rigidity). Results have clearly demonstrated that composite PCL/PLA stents are a highly promising solution to fulfilling the rigorous BRS requirements.

Keywords: 3D-printing; bioabsorbable; bioresorbable; composite; polymer; stent.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1

Figure 1

(a) 3D Tubular printer (b) 3D-printed stents [PCL in white, PLA in black] (c) Machine methodology. PCL: Polycaprolactone; PLA: Polylactide Acid.

Figure 2

Figure 2

Stent configurations: (a) Stent cell geometries employed; (b) Stent material/layers used.

Figure 3

Figure 3

Methodology followed to carry out the experiments. DMA: Dynamic Mechanical Analyzer.

Figure 4

Figure 4

3T3 Proliferation Results: (a) Average cell proliferation on each sample; (b) Main effect of cell geometry (6 radial cells, 2nd flow rate); (c) Main effect of flow rate (6 radial cells, A Geometry); (d) Main effect of number of cells (A Geometry, 2nd flow rate); (e) Main effect of plot of materials (6 radial cells, A Geometry, 2nd flow rate).

Figure 5

Figure 5

Confocal Laser Microscopy Images: (Left) PCL stent; (Right) PLA stent. Samples cultured with 3T3 fibroblast cells. Nucleus was stained with DAPI (blue) and actin cytoskeleton was stained with rhodamine-phalloidin (red).

Figure 6

Figure 6

Optical Nikon Microscope images of 3D-printed stents. Superior images show the general 3D view, while inferior images depict the ¼ section radial view. Samples numbered according to Table 3. PCL/PLA composite stent fabrication parameters.

Figure 7

Figure 7

Degradation rate results for PCL, PLA, PCL/PLA, and PLA/PCL stents.

Figure 8

Figure 8

DMA results for PCL, PLA, PCL/PLA and PLA/PCL stents.

Figure 9

Figure 9

Radial expansion behavior results: (a) Expansion and recoil of each sample, (b) Main effect plot of geometry and layer order on radial expansion, (c) Main effect plot of geometry and layer order on radial recoil. * Samples numbered according to Table 3. PCL/PLA composite stent fabrication parameters.

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