Publications

Graphene and graphene oxide (GO), due to their unique chemical and physical properties, possess biochemical characteristics that can trigger intercellular signals promoting tissue regeneration. Clinical applications of thin GO-derived sheets have inspired the development of various tissue regeneration and repair approaches. In this study, we demonstrate that ultrathin sheets of plasma-functionalized and reduced GO, with the oxygen content ranging from 3.2 % to 22 % and the nitrogen content from 0 % to 8.3 %, retain their essential mechanical and molecular integrity, and exhibit robust potential for regenerating bone tissue and blood vessels across multiple cellular and animal models. Initially, we observed the growth of blood vessels and bone tissue in vitro using these functionalized GO sheets on human adipose-derived mesenchymal stem cells and umbilical vein endothelial cells. Remarkably, our study indicates a 2.5-fold increase in mineralization and two-fold increase in tubule formation even in media lacking osteogenic and angiogenic supplements. Subsequently, we observed the initiation, conduction, and formation of bone and blood vessels in a rat tibial osteotomy model, evident from a marked 4-fold increase in the volume of low radio-opacity bone tissue and a significant elevation in connectivity density, all without the use of stem cells or growth factors. Finally, we validated these findings in a mouse critical-size calvarial defect model (33 % higher healing rate) and a rat skin lesion model (up to 2.5-fold increase in the number of blood vessels, and 35 % increase in blood vessels diameter). This study elucidates the proosteogenic and pro-angiogenic properties of both pristine and plasma-treated GO ultrathin films. These properties suggest their significant potential for clinical applications, and as valuable biomaterials for investigating fundamental aspects of bone and blood vessel regeneration.

JTD Keywords: Adhesion, Angiogenesis, Biocompatibilit, Bone regeneratio, Coatings, Fibronectin, Graphene oxide, Growth, Mesenchymal stem-cells, Osteoblast, Osteogenic differentiation, Plasma treatment, Protein, Tissue regeneration

Tissue engineering holds great promise for biomedical research and healthcare, offering alternatives to animal models and enabling tissue regeneration and organ transplantation. Three-dimensional (3D) bioprinting stands out for its design flexibility and reproducibility. Here, we present an integrated fluorescent light sheet bioprinting and imaging system that combines high printing speed (0.66 mm3 /s) and resolution (9 μm) with light sheet-based imaging. This approach employs direct laser patterning and a static light sheet for confined voxel crosslinking in photocrosslinkable materials. The developed bioprinter enables real-time monitoring of hydrogel crosslinking using fluorescent recovery after photobleaching (FRAP) and brightfield imaging as well as in situ light sheet imaging of cells. Human fibroblasts encapsulated in a thiol-ene click chemistry-based hydrogel exhibited high viability (83% ± 4.34%) and functionality. Furthermore, full-thickness skin constructs displayed characteristics of both epidermal and dermal layers and remained viable for 41 days. The integrated approach demonstrates the capabilities of light sheet bioprinting, offering high speed, resolution, and real-time characterization. Future enhancements involving solid-state laser scanning devices such as acousto-optic deflectors and modulators will further enhance resolution and speed, opening new opportunities in light-based bioprinting and advancing tissue engineering. This article is protected by copyright. All rights reserved.This article is protected by copyright. All rights reserved.

JTD Keywords: cadherin, collagen, culture, differentiation, fluorescence microscopy, full-thickness skin model, hydrogels, light sheet bioprinter, light sheet fluorescence microscopy, proliferation, survival, tissue engineering, Animal, Animals, Biofabrication, Bioprinting, Cell culture, Crosslinking, Fluorescence, Fluorescence microscopy, Full-thickness skin model, Hair follicle, Human, Humans, Hydrogel, Hydrogels, Image resolution, Laser patterning, Light sheet, Light sheet bioprinter, Light sheet fluorescence microscopy, Molecular biology, Photobleaching, Printing, three-dimensional, Procedures, Reproducibility, Reproducibility of results, Skin model, Three dimensional printing, Tissue, Tissue engineering, Tissue regeneration, Tissue scaffolds, Tissues engineerings

The incorporation of exogenous lactate into cardiac tissues is a regenerative strategy that is rapidly gaining attention. In this work, two polymeric platforms were designed to achieve a sustained release of lactate, combining immediate and prolonged release profiles. Both platforms contained electrospun poly(lactic acid) (PLA) fibers and an alginate (Alg) hydrogel. In the first platform, named L/K(x)/Alg-PLA, lactate and proteinase K (x mg of enzyme per 1 g of PLA) were directly loaded into the Alg hydrogel, into which PLA fibers were assembled. In the second platform, L/Alg-K(x)/PLA, fibers were produced by electrospinning a proteinase K:PLA solution and, subsequently, assembled within the lactate-loaded hydrogel. After characterizing the chemical, morphological, and mechanical properties of the systems, as well as their cytotoxicity, the release profiles of the two platforms were determined considering different amounts of proteinase K (x = 5.2, 26, and 52 mg of proteinase K per 1 g of PLA), which is known to exhibit a broad cleavage activity. The profiles obtained using L/Alg-K(x)/PLA platforms with x = 26 and 52 were the closest to the criteria that must be met for cardiac tissue regeneration. Finally, the amount of lactate directly loaded in the Alg hydrogel for immediate release and the amount of protein in the electrospinning solution were adapted to achieve a constant lactate release of around 6 mM per day over 1 or 2 weeks. In the optimized bioplatform, in which 6 mM lactate was loaded in the hydrogel, the amount of fibers was increased by a factor of ×3, the amount of enzyme was adjusted to 40 mg per 1 g of PLA, and a daily lactate release of 5.9 ± 2.7 mM over a period of 11 days was achieved. Accordingly, the engineered device fully satisfied the characteristics and requirements for heart tissue regeneration.

JTD Keywords: biodegradable fibers, cardiac tissue regeneration, cell, drug-release, elastic-modulus, electrospinning, heart, nanoindentation, plasma treatment, proteinase, scaffold, stiffness, Alginate, Biodegradable fibers, Cardiac tissue regeneration, Electrospinning, Nanoindentation, Plasma treatment, Proteinase, Skeletal-muscle

Tissue engineering is nowadays a powerful tool to restore damaged tissues and recover their normal functionality. Advantages over other current methods are well established, although a continuous evolution is still necessary to improve the final performance and the range of applications. Trends are nowadays focused on the development of multifunctional scaffolds with hierarchical structures and the capability to render a sustained delivery of bioactive molecules under an appropriate stimulus. Nanocomposites incorporating hydroxyapatite nanoparticles (HAp NPs) have a predominant role in bone tissue regeneration due to their high capacity to enhance osteoinduction, osteoconduction, and osteointegration, as well as their encapsulation efficiency and protection capability of bioactive agents. Selection of appropriated polymeric matrices is fundamental and consequently great efforts have been invested to increase the range of properties of available materials through copolymerization, blending, or combining structures constituted by different materials. Scaffolds can be obtained from different processes that differ in characteristics, such as texture or porosity. Probably, electrospinning has the greater relevance, since the obtained nanofiber membranes have a great similarity with the extracellular matrix and, in addition, they can easily incorporate functional and bioactive compounds. Coaxial and emulsion electrospinning processes appear ideal to generate complex systems able to incorporate highly different agents. The present review is mainly focused on the recent works performed with Hap-loaded scaffolds having at least one structural layer composed of core/shell nanofibers.

JTD Keywords: bone tissue, coaxial electrospinning, composite nanofibers, drug-release behavior, emulsion electrospinning, hydroxyapatite, in-vitro evaluation, mechanical-properties, osteogenic differentiation, pickering emulsions, protein adsorption, structured scaffolds, surface-initiated polymerization, tissue regeneration, Bone tissue, Coaxial electrospinning, Emulsion electrospinning, Hydroxyapatite, Multifunctional scaffolds, Poly(3-hydroxybutyrate) phb patches, Tissue regeneration

© 2020 Elsevier B.V. We examine different approaches for the controlled release of L-lactate, which is a signaling molecule that participates in tissue remodeling and regeneration, such as cardiac and muscle tissue. Robust, flexible, and self-supported 3-layers films made of two spin-coated poly(lactic acid) (PLA) layers separated by an electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) layer, are used as loading and delivery systems. Films with outer layers prepared using homochiral PLA and with nanoperforations of diameter 146 ± 70 experience more bulk erosion, which also contributes to the release of L-lactic acid, than those obtained using heterochiral PLA and with nanoperforations of diameter 66 ± 24. Moreover, the release of L-lactic acid as degradation product is accelerated by applying biphasic electrical pulses. The four approaches used for loading extra L-lactate in the 3-layered films were: incorporation of L-lactate at the intermediate PEDOT layer as primary dopant agent using (1) organic or (2) basic water solutions as reaction media; (3) substitution at the PEDOT layer of the ClO4− dopant by L-lactate using de-doping and re-doping processes; and (4) loading of L-lactate at the outer PLA layers during the spin-coating process. Electrical stimuli were applied considering biphasic voltage pulses and constant voltages (both negative and positive). Results indicate that the approach used to load the L-lactate has a very significant influence in the release regulation process, affecting the concentration of released L-lactate up to two orders of magnitude. Among the tested approaches, the one based on the utilization of the outer layers for loading, approach (4), can be proposed for situations requiring prolonged and sustained L-lactate release over time. The biocompatibility and suitability of the engineered films for cardiac tissue engineering has also been confirmed using cardiac cells.

JTD Keywords: biphasic voltage pulse, cardiac tissue regeneration, cardiomyocytes proliferation, conducting polymer, nanoperforated films, sustained delivery, Biphasic voltage pulse, Cardiac tissue regeneration, Cardiomyocytes proliferation, Conducting polymer, Nanoperforated films, Sustained delivery

Each bone of the skeleton constantly undergoes modeling during life to help it to adapt to changing biomechanical forces as well as remodeling to remove old bone and replace it with new, mechanically stronger bone to help preserve bone strength. Bone remodeling involves the removal of mineralized bone by osteoclasts, followed by the formation of bone matrix through the osteoblasts that subsequently become mineralized. All these assets make bone a suitable model for regeneration. Bone tissue can be grossly divided into inorganic mineral material (mostly HA), and organic material from cells and the extracellular matrix. This chapter outlines some of the bone diseases such as osteoporosis and Paget's disease. Bone can be considered as a biphasic composite material, with two phases: one the mineral and the other collagen. This combination confers better mechanical properties on the tissue than each component itself.

JTD Keywords: Bone biology, Bone cells, Bone diseases, Bone extracellular matrix, Bone mechanics, Bone remodeling, Bone tissue regeneration, Skeleton

Electrospinning is one of the most versatile and effective tools to produce nanostructured fibers in the biomedical science fields. The nanofibrous structure with diameters from tens to hundreds of nanometers largely mimics the native extracellular matrix (ECM) of many tissues. Thus far, a range of compositions including polymers and ceramics and their composites/hybrids have been successfully applied for generating electrospun nanofibers. Different processing tools in electrospinning set-ups and assemblies are currently developed to tune the morphology and properties of nanofibers. Herein, we demonstrate the electrospinning process and the electrospun biomaterials for specific use in tissue regeneration with some examples, involving different material combinations and fiber morphologies.

JTD Keywords: Ceramic, Composites, Electrospinning, Nanofi bers, Nanostructured fi bers, Polymer, Tissue regeneration