Printed Polycaprolactone Research Articles

Feasibility of Three-Dimensional Printing Polycaprolactone Coronary Bioresorbable Scaffolds

Feasibility of Three-Dimensional Printing Polycaprolactone Coronary Bioresorbable Scaffolds

Biomimetic 3D printed scaffolds for meniscus tissue engineering

The menisci distribute loads to protect the articular cartilage of the knee joint from excessive stress. Injuries to their avascular inner regions do not heal, disrupt function, and increase the risk for knee osteoarthritis. Meniscus tissue engineering aims to restore normal meniscus function by use of regenerated tissue on bioengineered scaffolds. The primary purpose of this study was to design and 3D print polycaprolactone scaffolds that recapitulate the shape and structural components of the meniscus extracellular matrix to provide a template and structural support for complete cell-based meniscus regeneration. A secondary aim was to characterize 3D printed polycaprolactone scaffold fibre architectures with varied fibre spacings, offsets between layers, and circumferential orientations in terms of their equilibrium compressive modulus. Meniscus scaffolds were produced layer-by-layer with a biomimetic fibre architecture inspired by the circumferentially- and radially- oriented collagen fibre bundles found in the native tissue. Suture tabs were incorporated to facilitate fixation at the meniscal horns and the coronary attachments. These scaffolds were designed to have 100% pore interconnectivity and 61% porosity. The equilibrium compressive modulus at 10% strain of the meniscus scaffold architecture was 18.8 ± 3.1MPa (mean ± standard deviation, n = 3) and ultimate load in a suture pull-out test on the anterior horn suture tab was 32N. The scaffolds produced in this study demonstrate a promising strategy for meniscus tissue engineering as they provide a complete biomimetic template for regeneration of functional components of the meniscus extracellular matrix.

A Bioactive Hydrogel and 3D Printed Polycaprolactone System for Bone Tissue Engineering.

In this study, a hybrid system consisting of 3D printed polycaprolactone (PCL) filled with hydrogel was developed as an application for reconstruction of long bone defects, which are innately difficult to repair due to large missing segments of bone. A 3D printed gyroid scaffold of PCL allowed a larger amount of hydrogel to be loaded within the scaffolds as compared to 3D printed mesh and honeycomb scaffolds of similar volumes and strut thicknesses. The hydrogel was a mixture of alginate, gelatin, and nano-hydroxyapatite, infiltrated with human mesenchymal stem cells (hMSC) to enhance the osteoconductivity and biocompatibility of the system. Adhesion and viability of hMSC in the PCL/hydrogel system confirmed its cytocompatibility. Biomineralization tests in simulated body fluid (SBF) showed the nucleation and growth of apatite crystals, which confirmed the bioactivity of the PCL/hydrogel system. Moreover, dissolution studies, in SBF revealed a sustained dissolution of the hydrogel with time. Overall, the present study provides a new approach in bone tissue engineering to repair bone defects with a bioactive hybrid system consisting of a polymeric scaffold, hydrogel, and hMSC.

Solvent Based 3D Printing of Biopolymer/Bioactive Glass Composite and Hydrogel for Tissue Engineering Applications

Three-dimensional (3D) bioprinting is an emerging technology in which scaffolding materials and cell-laden hydrogels may be deposited in a pre-determined fashion to create 3D porous constructs. A major challenge in 3D bioprinting is the slow degradation of melt deposited biopolymer. In this paper, we describe a new method for printing poly-caprolactone (PCL)/bioactive borate glass composite as a scaffolding material and Pluronic F127 hydrogel as a cell suspension medium. Bioactive borate glass was added to a mixture of PCL and organic solvent to make an extrudable paste using one syringe while hydrogel was extruded and deposited in between the PCL/borate glass filaments using a second syringe. The degradation of the PCL/borate glass composite scaffold with and without the presence of hydrogel was investigated by soaking the scaffold in minimum essential medium. The weight loss of the scaffold together with formation of a hydroxyapatite-like layer on the surface shows the excellent bioactivity of the scaffold.

Using synchrotron radiation inline phase-contrast imaging computed tomography to visualize three-dimensional printed hybrid constructs for cartilage tissue engineering.

Synchrotron radiation inline phase-contrast imaging combined with computed tomography (SR-inline-PCI-CT) offers great potential for non-invasive characterization and three-dimensional visualization of fine features in weakly absorbing materials and tissues. For cartilage tissue engineering, the biomaterials and any associated cartilage extracellular matrix (ECM) that is secreted over time are difficult to image using conventional absorption-based imaging techniques. For example, three-dimensional printed polycaprolactone (PCL)/alginate/cell hybrid constructs have low, but different, refractive indices and thicknesses. This paper presents a study on the optimization and utilization of inline-PCI-CT for visualizing the components of three-dimensional printed PCL/alginate/cell hybrid constructs for cartilage tissue engineering. First, histological analysis using Alcian blue staining and immunofluorescent staining assessed the secretion of sulfated glycosaminoglycan (GAGs) and collagen type II (Col2) in the cell-laden hybrid constructs over time. Second, optimization of inline PCI-CT was performed by investigating three sample-to-detector distances (SDD): 0.25, 1 and 3 m. Then, the optimal SDD was utilized to visualize structural changes in the constructs over a 42-day culture period. The results showed that there was progressive secretion of cartilage-specific ECM by ATDC5 cells in the hybrid constructs over time. An SDD of 3 m provided edge-enhancement fringes that enabled simultaneous visualization of all components of hybrid constructs in aqueous solution. Structural changes that might reflect formation of ECM also were evident in SR-inline-PCI-CT images. Summarily, SR-inline-PCI-CT images captured at the optimized SDD enables visualization of the different components in hybrid cartilage constructs over a 42-day culture period.

Analyzing Biological Performance of 3D-Printed, Cell-Impregnated Hybrid Constructs for Cartilage Tissue Engineering.

Three-dimensional (3D) bioprinting of hybrid constructs is a promising biofabrication method for cartilage tissue engineering because a synthetic polymer framework and cell-impregnated hydrogel provide structural and biological features of cartilage, respectively. During bioprinting, impregnated cells may be subjected to high temperatures (caused by the adjacent melted polymer) and process-induced mechanical forces, potentially compromising cell function. This study addresses these biofabrication issues, evaluating the heat distribution of printed polycaprolactone (PCL) strands and the rheological property and structural stability of alginate hydrogels at various temperatures and concentrations. The biocompatibility of parameters from these studies was tested by culturing 3D hybrid constructs bioprinted with primary cells from embryonic chick cartilage. During initial two-dimensional culture expansion of these primary cells, two morphologically and molecularly distinct cell populations ("rounded" and "fibroblastic") were isolated. The biological performance of each population was evaluated in 3D hybrid constructs separately. The cell viability, proliferation, and cartilage differentiation were observed at high levels in hybrid constructs of both cell populations, confirming the validity of these 3D bioprinting parameters for effective cartilage tissue engineering. Statistically significant performance variations were observed, however, between the rounded and fibroblastic cell populations. Molecular and morphological data support the notion that such performance differences may be attributed to the relative differentiation state of rounded versus fibroblastic cells (i.e., differentiated chondrocytes vs. chondroprogenitors, respectively), which is a relevant issue for cell-based tissue engineering strategies. Taken together, our study demonstrates that bioprinting 3D hybrid constructs of PCL and cell-impregnated alginate hydrogel is a promising approach for cartilage tissue engineering.

Segmental tracheal reconstruction by 3D-printed scaffold: Pivotal role of asymmetrically porous membrane.

Three-dimensional (3D) printed scaffold for tracheal reconstruction can substitute the conventional treatment of tracheal stenosis. This study investigated the survival outcomes of segmental tracheal reconstruction using 3D printed polycaprolactone (PCL) scaffold with or without asymmetrically porous membrane in rabbit animal model. Animal study. Six mature New Zealand white rabbits were categorized into two groups (three animals for each) according to the procedures they received: tracheal reconstruction using 3D printed PCL scaffold without asymmetrically porous membrane (group 1) versus with asymmetrically porous membrane (group 2). We compared the endoscopic findings of tracheal lumen, radiologic assessment using microcomputed tomography (CT) scanner and histologic findings. Overall survival duration after procedure was compared in both groups. The survival of group 2 was longer than group 1 (21, 37, 46 days vs. 4, 10, 12 days, respectively). Although mucosal regeneration in tracheal lumen was not full enough in both groups, the patency was well maintained in group 2. Micro-CT and histologic analysis showed that there were tracheal narrowing in the whole length in group 1, whereas only the anastomosis site was stenotic in group 2. Asymmetrically porous membrane reinforced by 3D printed mesh is promising as a 360-degree tracheal substitute with comparable survival and luminal patency. Further study is necessary to minimize the narrowing of the anastomosis site and improve the mucosal regeneration for longer survival. NA. Laryngoscope, 126:E304-E309, 2016.