Angiogenic potential of gellan-gum-based hydrogels for application in nucleus pulposus regeneration: in vivo study.
ABSTRACT Hydrogels for nucleus pulposus (NP) regeneration should be able to comprise a nonangiogenic or even antiangiogenic feature. Gellan gum (GG)-based hydrogels have been reported to possess adequate properties for being used as NP substitutes in acellular and cellular strategies, due to its ability to support cell encapsulation, adequate mechanical properties, and noncytotoxicity. In this study, the angiogenic response of GG-based hydrogels was investigated by performing the chorioallantoic membrane assay. The convergence of macroscopic blood vessels toward the GG, ionic-crosslinked methacrylated GG (iGG-MA), and photo-crosslinked methacrylated GG (phGG-MA) hydrogel discs was quantified. Gelatin sponge (GSp) and filter paper (FP) alone and with vascular endothelial growth factor were used as controls of angiogenesis. The images obtained were digitally processed and analyzed by three independent observers. The macroscopic blood vessel quantification demonstrated that the GG-based hydrogels are not angiogenic as compared with FP controls. No statistical differences between the GG-based hydrogels tested in respect to its angiogenic ability were observed. Hematoxylin and eosin staining and SNA-lectin immunohistochemistry assay indicated that the iGG-MA and phGG-MA hydrogels do not allow the ingrowth of chick endothelial cells, following 4 days of implantation. On the contrary, GG, GSp, and FP controls allowed cell infiltration. The histological data also indicated that the GG-based hydrogels do not elicit any acute inflammatory response. The results showed that the GG, iGG-MA, and phGG-MA hydrogels present different permeability to cells but functioned as a physical barrier for vascular invasion. These hydrogels present promising and tunable properties for being used as NP substitutes in the treatment of degenerative intervertebral disc.
SourceAvailable from: Sonia Moniz
[Show abstract] [Hide abstract]
ABSTRACT: This review evaluates hydrogel-forming polymers that are suitable for soft tissue engineering with a focus on materials that can be fabricated using additive manufacturing (3D-printing). An overview of the specific material requirements for hydrogel-based tissue engineering constructs is presented. This is followed by an explanation of the various hydrogel-forming polymer classes that includes a detailed examination of material properties that are critical for extrusion printing. Specifically, mechanisms for hydrogel formation, degradation, and biological response, activity and compatibility are explored. A discussion of extrusion printing strategies for printable hydrogel-forming polymers is then presented in conjunction with a list of considerations to guide future tissue engineering developments.04/2015; 3(20). DOI:10.1039/C5TB00393H
[Show abstract] [Hide abstract]
ABSTRACT: Degeneration of the intervertebral disc (IVD) represents a significant musculoskeletal disease burden. Tissue Engineering has been proposing several strategies comprising the use of biodegradable materials to prepare scaffolds that can present similar mechanical properties to native IVD tissues. However, this might be insufficient, since the patient’s intervertebral space geometry must be replicated to allow the appropriate implant fixation and integration. Herein, it is proposed the use of Reverse Engineering and Rapid Prototyping techniques applied to rabbit models aiming to prepare custom-tailored annulus fibrosus scaffolds. The IVD reverse engineered architecture was obtained by means of micro-Computed Tomography acquisition and three-dimensional modelling, resulting in a computer-aided design that replicates the original rabbit IVD. Later, a fused deposition modelling three-dimensional printer was used to produce the scaffolds with different geometries from the computer-aided design, using polycaprolactone (PCL) with 100% infill density. The microstructure of the PCL scaffolds was investigated by scanning electron microscopy (SEM), which allowed observing an adequate fusion adhesion between layers. The SEM images revealed that, until a moderate resolution, the porosities manually designed in the computer-aided design model were successfully replicated. The PCL scaffolds’ three-dimensional architecture was also assessed by means of micro-Computed Tomography analysis. Compressive stiffness was determined using a mechanical testing system. Results showed higher values as compared to that of human IVDs (5.9-6.7 kN/mm vs. 1.2 kN/mm, respectively). In vitro studies were performed to investigate possible cytotoxicity of the polycaprolactone scaffolds’ leachables. The results showed that the custom-tailored PCL scaffolds do not have any deleterious cytotoxic effect over annulus fibrosus cells and mouse lung fibroblasts cell line. This study proposed a simple, rapid and low-cost strategy to fabricate custom-tailored annulus fibrosus scaffolds. In the future, this strategy might be used in association with nucleus pulposus regeneration strategies that can possibly allow developing tissue engineered total disc replacement implants specific to each patient, aiming at full IVD regeneration.Biofabrication 01/2015; 7(1). DOI:10.1088/1758-5090/7/1/015008 · 4.30 Impact Factor