Composition-property relationships for an experimental composite nerve guidance conduit: evaluating cytotoxicity and initial tensile strength

Aminosilane Functionalized Aligned Fiber PCL Scaffolds for Peripheral Nerve Repair

Silane modification is a simple and cost-effective tool to modify existing biomaterials for tissue engineering applications. Aminosilane layer deposition has previously been shown to control NG108-15 neuronal cell and primary Schwann cell adhesion and differentiation by controlling deposition of ─NH2 groups at the submicron scale across the entirety of a surface by varying silane chain length. This is the first study toreport depositing 11-aminoundecyltriethoxysilane (CL11) onto aligned Polycaprolactone (PCL) scaffolds for peripheral nerve regeneration. Fibers are manufactured via electrospinning and characterized using water contact angle measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Confirmed modified fibers are investigated using in vitro cell culture of NG108-15 neuronal cells and primary Schwann cells to determine cell viability, cell differentiation, and phenotype. CL11-modified fibers significantly support NG108-15 neuronal cell and Schwann cell viability. NG108-15 neuronal cell differentiation maintains Schwann cell phenotype compared to unmodified PCL fiber scaffolds. 3D ex vivo culture of Dorsal root ganglion explants (DRGs) confirms further Schwann cell migration and longer neurite outgrowth from DRG explants cultured on CL11 fiber scaffolds compared to unmodified scaffolds. Thus, a reproducible and cost-effective tool is reported to modify biomaterials with functional amine groups that can significantly improve nerve guidance devices and enhance nerve regeneration.

The optimal number and location of sutures in conduit-assisted primary digital nerve repair

We evaluated the strength of conduit-assisted primary digital nerve repairs, with varying suture location and number, in 56 digital nerves from cadavers. Maximum load to failure was tested for the following seven repairs, designated by the number of epineurial sutures followed by the number of sutures at each end of the conduit: 4 (epineurial sutures)/0 (sutures at each end of conduit), 4/4, 4/2, 2/2, 0/4, 0/2, 0/1. The 4/4 repair (3.0 N) was significantly stronger than 4/0 (1.5 N), 2/2 (1.6 N), 0/4 (2.0 N), 0/2 (1.4 N) and 0/1 (1.1 N). Considering all repair types, there was a significant correlation between suture number and failure load, with the strongest repair having a total of 12 sutures, which is impractical. Reasonable repair options, which have two sutures at each end of the conduit and either two or no epineurial sutures, are as strong as a four-suture epineurial repair but have less sutures at the coaptation site.

Composition-property relationships for radiopaque composite materials: pre-loaded drug-eluting beads for transarterial chemoembolization

The purpose of this study was to synthesize and optimize intrinsically radiopaque composite embolic microspheres for sustained release of doxorubicin in drug-eluting bead transarterial chemoembolization. Using a design of experiments approach, 12 radiopaque composites composed of polylactic-co-glycolic acid and a radiopaque glass (ORP5) were screened over a range of compositions and examined for radiopacity (computed tomography) and density. In vitro cell viability was determined using an extract assay derived from each composition against the human hepatocellular carcinoma cell line, HepG2. Mathematical models based on a D-Optimal response surface methodology were used to determine the preferred radiopaque composite. The resulting radiopaque composite was validated and subsequently loaded with doxorubicin between 0 and 1.4% (wt% of polylactic-co-glycolic acid) to yield radiopaque composite drug-eluting beads. Thereafter, the radiopaque composite drug-eluting beads were subjected to an elution study (up to 168 h) to determine doxorubicin release profiles (UV-Vis spectroscopy) and in vitro cell viability. Radiopaque composites evaluated for screening purposes had densities between 1.28 and 1.67 g.cm(-3), radiopacity ranged between 211 and 1450HU and cell viabilities between 91 and 106% were observed. The optimized radiopaque composite comprised 23 wt% polylactic-co-glycolic acid and 60 wt% ORP5 with a corresponding density of 1.63 ± 0.001 g.cm(-3), radiopacity at 1930 ± 44HU and cell viability of 89 ± 7.6%. Radiopaque composite drug-eluting beads provided sustained doxorubicin release over 168 h. In conclusion, the mathematical models allowed for the identification and synthesis of a unique radiopaque composite. The optimized radiopaque composite had similar density and cell viability to commercially available embolic microspheres. It was possible to preload doxorubicin into radiopaque composite drug-eluting beads, such that sustained release was possible under simulated physiological conditions.

Aligned collagen-GAG matrix as a 3D substrate for Schwann cell migration and dendrimer-based gene delivery

The development of artificial off-the-shelf conduits that facilitate effective nerve regeneration and recovery after repair of traumatic nerve injury gaps is of fundamental importance. Collagen-glycosaminoglycan (GAG) matrix mimicking Schwann cell (SC) basal lamina has been proposed as a suitable and biologically rational substrate for nerve regeneration. In the present study, we have focused on the permissiveness of this matrix type for SC migration and repopulation, as these events play an essential role in nerve remodeling. We have also demonstrated that SCs cultured within collagen-GAG matrix are compatible with non-viral dendrimer-based gene delivery, that may allow conditioning of matrix-embedded cells for future gene therapy applications.

How Can Nanotechnology Help to Repair the Body? Advances in Cardiac, Skin, Bone, Cartilage and Nerve Tissue Regeneration

Nanotechnologists have become involved in regenerative medicine via creation of biomaterials and nanostructures with potential clinical implications. Their aim is to develop systems that can mimic, reinforce or even create in vivo tissue repair strategies. In fact, in the last decade, important advances in the field of tissue engineering, cell therapy and cell delivery have already been achieved. In this review, we will delve into the latest research advances and discuss whether cell and/or tissue repair devices are a possibility. Focusing on the application of nanotechnology in tissue engineering research, this review highlights recent advances in the application of nano-engineered scaffolds designed to replace or restore the followed tissues: (i) skin; (ii) cartilage; (iii) bone; (iv) nerve; and (v) cardiac.

Mixture designs to assess composition–structure–property relationships in SiO2–CaO–ZnO–La2O3–TiO2–MgO–SrO–Na2O glasses: Potential materials for embolization

Embolization with micron-sized particulates is widely applied to treat uterine fibroids. The objective of this work was to develop mixture designs to predict materials composition–structure–property relationships for the SiO2–CaO–ZnO–La2O3–TiO2–MgO–SrO–Na2O glass system and compare its fundamental materials properties (density and cytocompatibility), against a state-of-the-art embolic agent (contour polyvinyl alcohol) to assess the potential of these materials for embolization therapies. The glass structures were evaluated using 29Si MAS NMR to identify chemical shift and line width; the particulate densities were determined using helium pycnometry and the cell viabilities were assessed via MTT assay. 29Si MAS NMR results indicated peak maxima for each glass in the range of −82.3 ppm to −89.9 ppm; associated with Q2 to Q3 units in silicate glasses. All experimental embolic compositions showed enhanced in vitro compatibility in comparison to Contour PVA with the exceptions of ORP9 and ORP11 (containing no TiO2). In this study, optimal compositions for cell viability were obtained for the following compositional ranges: 0.095–0.188 mole fraction ZnO; 0.068–0.159 mole fraction La2O3; 0.545–0.562 mole fraction SiO2 and 0.042–0.050 mole fraction TiO2. To ensure ease of producibility in obtaining good melts, a maximum loading of 0.068 mole fraction La2O3 is required. This is confirmed by the desirability approach, for which the only experimental composition (ORP5) of the materials evaluated was presented as an optimum composition; combining high cell viability with ease of production (0.188 mole fraction ZnO; 0.068 mole fraction La2O3; 0.562 mole fraction SiO2 and 0.042 mole fraction TiO2).