Showing papers by "Vladimir Mironov published in 2016"

Biofabrication: reappraising the definition of an evolving field

Abstract: Biofabrication is an evolving research field that has recently received significant attention. In particular, the adoption of Biofabrication concepts within the field of Tissue Engineering and Regenerative Medicine has grown tremendously, and has been accompanied by a growing inconsistency in terminology. This article aims at clarifying the position of Biofabrication as a research field with a special focus on its relation to and application for Tissue Engineering and Regenerative Medicine. Within this context, we propose a refined working definition of Biofabrication, including Bioprinting and Bioassembly as complementary strategies within Biofabrication.

A Perspective on 4D Bioprinting

Abstract: 3D bioprinting has been invented for more than a decade. A disruptive progress is still lacking for the field to significantly move forward. Recently, the invention of 4D printing technology may point a way and hence the birth of 4D bioprinting. However, 4D bioprinting is not well defined and appear to have a few distinct early forms. In this article, a personal perspective on the early forms of 4D bioprinting is presented and a definition for 4D bioprinting is proposed.

Delivery of Human Adipose Stem Cells Spheroids into Lockyballs

Abstract: Adipose stem cells (ASCs) spheroids show enhanced regenerative effects compared to single cells. Also, spheroids have been recently introduced as building blocks in directed self-assembly strategy. Recent efforts aim to improve long-term cell retention and integration by the use of microencapsulation delivery systems that can rapidly integrate in the implantation site. Interlockable solid synthetic microscaffolds, so called lockyballs, were recently designed with hooks and loops to enhance cell retention and integration at the implantation site as well as to support spheroids aggregation after transplantation. Here we present an efficient methodology for human ASCs spheroids biofabrication and lockyballs cellularization using micro-molded non-adhesive agarose hydrogel. Lockyballs were produced using two-photon polymerization with an estimated mechanical strength. The Young's modulus was calculated at level 0.1362 +/-0.009 MPa. Interlocking in vitro test demonstrates high level of loading induced interlockability of fabricated lockyballs. Diameter measurements and elongation coefficient calculation revealed that human ASCs spheroids biofabricated in resections of micro-molded non-adhesive hydrogel had a more regular size distribution and shape than spheroids biofabricated in hanging drops. Cellularization of lockyballs using human ASCs spheroids did not alter the level of cells viability (p › 0,999) and gene fold expression for SOX-9 and RUNX2 (p › 0,195). The biofabrication of ASCs spheroids into lockyballs represents an innovative strategy in regenerative medicine, which combines solid scaffold-based and directed self-assembly approaches, fostering opportunities for rapid in situ biofabrication of 3D building-blocks.

Patterning of tissue spheroids biofabricated from human fibroblasts on the surface of electrospun polyurethane matrix using 3D bioprinter

Abstract: Organ printing is a computer-aided additive biofabrication of functional three-dimensional human tissue and organ constructs according to digital model using the tissue spheroids as building blocks. The fundamental biological principle of organ printing technology is a phenomenon of tissue fusion. Closely placed tissue spheroids undergo tissue fusion driven by surface tension forces. In order to ensure tissue fusion in the course of post-printing, tissue spheroids must be placed and maintained close to each other. We report here that tissue spheroids biofabricated from primary human fibroblasts could be placed and maintained on the surface of biocompatible electrospun polyurethane matrix using 3D bioprinter according to desirable pattern. The patterned tissue spheroids attach to polyurethane matrix during several hours and became completely spread during several days. Tissue constructions biofabricated by spreading of patterned tissue spheroids on the biocompatible electrospun polyurethane matrix is a novel technological platform for 3D bioprinting of human tissue and organs.

Delivery of Human Adipose Stem Cells Spheroids into Lockyballs

Abstract: Adipose stem cells (ASCs) spheroids show enhanced regenerative effects compared to single cells. Also, spheroids have been recently introduced as building blocks in directed self-assembly strategy. Recent efforts aim to improve long-term cell retention and integration by the use of microencapsulation delivery systems that can rapidly integrate in the implantation site. Interlockable solid synthetic microscaffolds, so called lockyballs, were recently designed with hooks and loops to enhance cell retention and integration at the implantation site as well as to support spheroids aggregation after transplantation. Here we present an efficient methodology for human ASCs spheroids biofabrication and lockyballs cellularization using micro-molded non-adhesive agarose hydrogel. Lockyballs were produced using two-photon polymerization with an estimated mechanical strength. The Young’s modulus was calculated at level 0.1362 +/-0.009 MPa. Interlocking in vitro test demonstrates high level of loading induced interlockability of fabricated lockyballs. Diameter measurements and elongation coefficient calculation revealed that human ASCs spheroids biofabricated in resections of micro-molded non-adhesive hydrogel had a more regular size distribution and shape than spheroids biofabricated in hanging drops. Cellularization of lockyballs using human ASCs spheroids did not alter the level of cells viability (p › 0,999) and gene fold expression for SOX-9 and RUNX2 (p › 0,195). The biofabrication of ASCs spheroids into lockyballs represents an innovative strategy in regenerative medicine, which combines solid scaffold-based and directed self-assembly approaches, fostering opportunities for rapid in situ biofabrication of 3D building-blocks.

From 3D Bioprinters to a fully integrated Organ Biofabrication Line

Abstract: About 30 years ago, the 3D printing technique appeared. From that time on, engineers in medical science field started to look at 3D printing as a partner. Firstly, biocompatible and biodegradable 3D structures for cell seeding called "scaffolds" were fabricated for in vitro and in vivo animal trials. The advances proved to be of great importance, but, the use of scaffolds faces some limitations, such as low homogeneity and low density of cell aggregates. In the last decade, 3D bioprinting technology emerged as a promising approach to overcome these limitations and as one potential solution to the challenge of organ fabrication, to obtain very similar 3D human tissues, not only for transplantation, but also for drug discovery, disease research and to decrease the usage of animals in laboratory experimentation. 3D bioprinting allowed the fabrication of 3D alive structures with higher and controllable cell density and homogeneity. Other advantage of biofabrication is that the tissue constructs are solid scaffold-free. This paper presents the 3D bioprinting technology; equipment development, stages and components of a complex Organ Bioprinting Line (OBL) and the importance of developing a Virtual OBL.

Modeling and Simulation of Diffusion Process in Tissue Spheroids Encaged into Microscaffolds (Lockyballs)

Abstract: Nutrition, organization, growth and signal transduction in cells are largely determined by diffusion mechanisms. The complex three-dimensional shapes of cellular environment complicate the experimental analysis and computational simulation of diffusion in live cells. Three-dimensional cell aggregates are called tissue spheroids and they are widely used in the field of tissue engineering because emulate in vivo microenvironments more accurately than conventional monolayer cultures. The greater contact of the cells with the culture medium is directly related to oxygen diffusion and thereafter with the cell viability and the increase of proliferation rate. Due to the characteristics of a 3D environment, at some zones within the tissue spheroids the cells are not equally exposed to the culture medium, and the result of an insufficient supply of oxygen to the cell impact in the formation of microenvironments with decreased oxygen, nutrients and soluble factors produced by cellular metabolism leading to the formation of low proliferation areas and consequently hypoxia and necrosis (cell death). The fusion of cells also changes the catabolites flow, generating a very heterogeneous diffusion. The idea of this work is to develop and improve microscaffolds based on the concept of lockyballs that have cell support function for tissue engineering. These microscaffolds are composed by hooks (which attach to other hooks or loops of neighbor lockyballs), loops (elevated pentagons, which allows hooks attaching) and tubes (that preventing entry of cells). It is presented one original type of lockyball (control) which has no internal structure (it is a hollow structure) further other three types of lockyballs. The first model has a spherical outer structure and inner hollow microsphere constituted by pores with diameters smaller than the cell ones, whose function would be to prevent cell entry. The second model has tubes constituted by pores and the third model has a spiral tube constituted by pores too. These inner structures provide an environment suitable to the diffusion gradient necessary for the cell viability of the spheroid avoiding necrosis. The first stage of the work consisted on the generation of different three-dimensional models by Computer Aided Design (CAD) software Rhinoceros 5.0. At the second stage, the CAD model was imported into volume element method (VEM) software (Star-CCM +/CD-Adapco) to perform computational fluid simulation (CFD). The CFD simulations were essential to predict the diffusion phenomenon inside the whole 3D structure. The development of new microscaffolds models can enhance the regenerative capacity and 3D tissues construction.

Spreading of Tissue Spheroids on an Electrospun Polyurethane Matrix

Abstract: Tissue spheroids formed from fibroblasts using a micromolded non-adhesive hydrogel were located using a three-dimensional (3D) bioprinter on the surface of a nanofibrous polyurethane matrix produced by electrospinning. It was shown that the tissue spheroids attach to the matrix surface within a few hours and completely flatten after several days, indicating high biocompatibility of the matrix used. Tissue structures formed by the attachment and spreading of tissue spheroids on an electrospun matrix are a new technological platform for biofabrication and 3D bioprinting of tissues and organs.

Development and Implantation of a Biocompatible Auricular Prosthesis

Abstract: A patient-specific auricular prosthesis made of biocompatible non-biodegradable polyurethane with biomimetic mechanical properties was developed and printed using a 3D printer. A three-point bending study of the mechanical properties of printed samples of this material showed that the printed prosthesis is similar in its material properties to natural human aural cartilage. After subcutaneous implantation into mice the auricular prosthesis maintained its initial shape and size. Thus, 3D printing enables creation of a patient-specific biocompatible auricular prosthesis with biomimetic material properties and the ability to maintain the original shape and size after in vivo implantation.

Nanostructural features of contacts of fibroblasts with dual-scale bioсompatible polyurethane scaffold

Abstract: This paper presents a study of nanostructural features of contacts of bioprinted tissue spheroids with polyurethane dual scale biocompatible scaffold made by three-dimensional printing and electrospinning. Analysis of nanostructural features of cell contacts was carryed out by scanning probe microscopy with use of experimental setup combining ultramicrotome and scanning probe microscope. Measured mean cell volume is 460 ± 104 μm3, mean contact area of cells with scaffold fibers–104.8 μm2 per cell (16.7% of total cell area). Maximum distance of migrating cells from spheroid border at 48 h. is ~200 μm, what corresponds to mean velocity of cell migration more than 4 μm/h. Obtained quantitative characteristics of micro- and nanostructure of human fibroblast cell contacts with elecrospun polyurethane scaffold secure high efficacy of tissue regeneration with its usage for implanted bioprinted dual scale tissue-engineered scaffolds.

Design and Implementation of Novel Multifunctional 3D Bioprinter

Abstract: Complete List of Authors: Hesuani, Yusef ; 3-D Bioprinting Solution Pereira, Frederico; 3-D Bioprinting Solution Parfenov, Vladislav; 3-D Bioprinting Solution Koudan, Elizaveta; 3-D Bioprinting Solution Mitryashkin, Alexander; 3-D Bioprinting Solution Replyanski, Nikita; 3-D Bioprinting Solution Kasyanov, Vladimir; Riga Stradins University, Laboratory of Biomechanics; Riga Technical University, Biomechanical Laboratory Knyazeva, Anastasia; 3-D Bioprinting Solution Bulanova, Elena; 3-D Bioprinting Solution Mironov, Vladimir; 3-D Bioprinting Solution

3D Modelling and Structural Simulation of Scaffolds for Cardiovascular Implants

Abstract: Cardiovascular disease remains as one of the main problems in contemporary health care worldwide. Several studies of the cardiac prostheses have been held since 60s with the advent of cardiopulmonary bypass. The mechanical properties of blood vessels, arteries and valves depend on collagen and elastic fibers, as well as on smooth muscle cells and ground substances. Many works about three-dimensional finite element model of the arterial wall segment and the heart valves assume the biological material to be homogeneous and isotropic. This configuration is a simplified way to reduce the complexity of biological structures. The primary purpose of this study was to assess the effects of fiber design and orientation on the stress distribution in a 3D model for cardiovascular implants and predict the elastic modulus of scaffolds designed.