3D Bioprinting In Bone And Cartilage Regeneration Review

 Bone and articular cartilage degeneration and damage are the most common causes of musculoskeletal disability. 3D bioprinting can help regenerate these structures. Autologous/allogeneic bone and cartilage transplantation, vascularized bone transplantation, autologous chondrocyte implantation, mosaicplasty, and joint replacement are all common clinical and surgical procedures. In vitro layer-by-layer printing of biological materials, living cells, and other biologically active substances using 3D bio printing technology is anticipated to replace the aforementioned repair methods. With the ability to prepare various organs and tissue structures, 3D bio printing has largely solved the issue of insufficient organ donors. Researchers use biomedical materials and cells as discrete materials. Bioprinting cell selection and its use in bone and cartilage repair are the primary topics of discussion in this paper

Trends in Tissue Engineering for Blood Vessels

Over the years, cardiovascular diseases continue to increase and affect not only human health but also the economic stability worldwide. The advancement in tissue engineering is contributing a lot in dealing with this immediate need of alleviating human health. Blood vessel diseases are considered as major cardiovascular health problems. Although blood vessel transplantation is the most convenient treatment, it has been delimited due to scarcity of donors and the patient's conditions. However, tissue-engineered blood vessels are promising alternatives as mode of treatment for blood vessel defects. The purpose of this paper is to show the importance of the advancement on biofabrication technology for treatment of soft tissue defects particularly for vascular tissues. This will also provide an overview and update on the current status of tissue reconstruction especially from autologous stem cells, scaffolds, and scaffold-free cellular transplantable constructs. The discussion of this paper will be focused on the historical view of cardiovascular tissue engineering and stem cell biology. The representative studies featured in this paper are limited within the last decade in order to trace the trend and evolution of techniques for blood vessel tissue engineering

The fusion of tissue spheroids attached to pre-stretched electrospun polyurethane scaffolds

Publisher Copyright: © 2014, © The Author(s) 2014. Copyright: Copyright 2019 Elsevier B.V., All rights reserved.Effective cell invasion into thick electrospun biomimetic scaffolds is an unsolved problem. One possible strategy to biofabricate tissue constructs of desirable thickness and material properties without the need for cell invasion is to use thin (<2 µm) porous electrospun meshes and self-assembling (capable of tissue fusion) tissue spheroids as building blocks. Pre-stretched electrospun meshes remained taut in cell culture and were able to support tissue spheroids with minimal deformation. We hypothesize that elastic electrospun scaffolds could be used as temporal support templates for rapid self-assembly of cell spheroids into higher order tissue structures, such as engineered vascular tissue. The aim of this study was to investigate how the attachment of tissue spheroids to pre-stretched polyurethane scaffolds may interfere with the tissue fusion process. Tissue spheroids attached, spread, and fused after being placed on pre-stretched polyurethane electrospun matrices and formed tissue constructs. Efforts to eliminate hole defects with fibrogenic tissue growth factor-β resulted in the increased synthesis of collagen and periostin and a dramatic reduction in hole size and number. In control experiments, tissue spheroids fuse on a non-adhesive hydrogel and form continuous tissue constructs without holes. Our data demonstrate that tissue spheroids attached to thin stretched elastic electrospun scaffolds have an interrupted tissue fusion process. The resulting tissue-engineered construct phenotype is a direct outcome of the delicate balance of the competing physical forces operating during the tissue fusion process at the interface of the pre-stretched elastic scaffold and the attached tissue spheroids. We have shown that with appropriate treatments, this process can be modulated, and thus, a thin pre-stretched elastic polyurethane electrospun scaffold could serve as a supporting template for rapid biofabrication of thick tissue-engineered constructs without the need for cell invasion.publishersversionPeer reviewe

Development of Biomimetic Models of Human Cardiac Tissue

The leading cause of death worldwide is cardiovascular disease (CVD). Myocardial infarction (MI) (i.e., heart attack) makes up ~8.5% of CVD and is a common cause of heart failure with a 40% five-year mortality after the first MI. This highlights a substantial patient population and an urgent need to develop new therapeutic strategies (e.g., regenerative cell therapies). Moreover, this also indicates that current models may not sufficiently recapitulate human cardiac tissue. To date, drug development strategies have largely depended on high throughput 2D cell models and pre-clinical testing in animal models of MI leading to minimal improvements in the heart failure treatment paradigm over the past 20 years. Relevant human cardiac models would provide insight into human cardiac tissue physiology and maturation while also providing an advanced in vitro screening tool to explore heart failure pathogenesis. Cardiac tissue engineering has allowed for advances in the development of cardiac constructs by combining developments in biomaterials, 3D microtissue culture, and human induced pluripotent stem cells (hiPSC) technology. Notably, approaches that mimic the natural processes in the body (i.e., biomimetic) have led to further insight into cardiac physiology. Here, I have pursued biomimetic strategies to create a biomimetic model of human cardiac tissue using hiPSC-derived cardiomyocytes (hiPSC-CMs). Throughout this development, I explored the role of the matrix microenvironment on cell behavior using functionalized alginate, the influence of pacemaker-like exogenous electrical stimulation on the maturation of hiPSC-CM spheroids with endogenous electrically conductive nanomaterials, and the development of vascularized, functional cardiac organoids by mimicking the coronary vasculogenesis stage of cardiac development. The research established here provided a biomimetic groundwork for future development into in vitro human cardiac tissue models for applications in basic research, drug discovery, and cell therapy

POLYSACCHARIDE-BASED SHEAR THINNING HYDROGELS FOR THREE-DIMENSIONAL CELL CULTURE

The recreation of the complicated tissue microenvironment is essential to reduce the gap between in vitro and in vivo research. Polysaccharide-based hydrogels form excellent scaffolds to allow for three-dimensional cell culture owing to the favorable properties such as capability to absorb large amount of water when immersed in biological fluids, ability to form “smart hydrogels” by being shear-thinning and thixotropic, and eliciting minimum immunological response from the host. In this study, the biodegradable shear-thinning polysaccharide, gellan-gum based hydrogel was investigated for the conditions and concentrations in which it can be applied for the adhesion, propagation and assembly of different mammalian cell types in an unmodified state, at physiological conditions of temperature. Cell studies, to show successful propagation and assembly into three-dimensional structures, were performed in the range of hydrogels which were deemed to be optimum for cell culture and the cell types were chosen to represent each embryonic germ layer, i.e., human neural stem cells for ectoderm, human brain microvasculature cells for mesoderm, and murine β-cells for endoderm, along with a pluripotent cell line of human induced pluripotent stem cells, derived from human foreskin fibroblasts. Three-dimensional cell organoid models, to allow for gellan gum based bioprinting, were also developed using human induced pluripotent stem cells and human neural stem cells

Construction of 3D in vitro models by bioprinting human pluripotent stem cells: Challenges and opportunities

Three-dimensional (3D) printing of biological material, or 3D bioprinting, is a rapidly expanding field with interesting applications in tissue engineering and regenerative medicine. Bioprinters use cells and biocompatible materials as an ink (bioink) to build 3D structures representative of organs and tissues, in a controlled manner and with micrometric resolution. Human embryonic (hESCs) and induced (hiPSCs) pluripotent stem cells are ideally able to provide all cell types found in the human body. A limited, but growing, number of recent reports suggest that cells derived by differentiation of hESCs and hiPSCs can be used as building blocks in bioprinted human 3D models, reproducing the cellular variety and cytoarchitecture of real tissues. In this review we will illustrate these examples, which include hepatic, cardiac, vascular, corneal and cartilage tissues, and discuss challenges and opportunities of bioprinting more demanding cell types, such as neurons, obtained from human pluripotent stem cells

3D Bioprinting for Tissue and Organ Fabrication

The field of regenerative medicine has progressed tremendously over the past few decades in its ability to fabricate functional tissue substitutes. Conventional approaches based on scaffolding and microengineering are limited in their capacity of producing tissue constructs with precise biomimetic properties. Three-dimensional (3D) bioprinting technology, on the other hand, promises to bridge the divergence between artificially engineered tissue constructs and native tissues. In a sense, 3D bioprinting offers unprecedented versatility to co-deliver cells and biomaterials with precise control over their compositions, spatial distributions, and architectural accuracy, therefore achieving detailed or even personalized recapitulation of the fine shape, structure, and architecture of target tissues and organs. Here we briefly describe recent progresses of 3D bioprinting technology and associated bioinks suitable for the printing process. We then focus on the applications of this technology in fabrication of biomimetic constructs of several representative tissues and organs, including blood vessel, heart, liver, and cartilage. We finally conclude with future challenges in 3D bioprinting as well as potential solutions for further development.United States. Office of Naval Research. Young Investigator ProgramNational Institutes of Health (U.S.) (Grants EB012597, AR057837, DE021468, HL099073 and R56AI105024)Presidential Early Career Award for Scientists and Engineer

Bioengenharia de sistemas nano estruturados com base em superfícies inspiradas na natureza para regeneração de tecidos humanos

Modular tissue engineering aims to mimic the complexity of native tissue with well-defined 3D architectures and synergistic interactions of various cell lines by generating repeated functional modular units that will be assembled into a functional tissue. These modular blocks should exhibit specific microstructural characteristics to mimic the complex architecture of native tissues. For the direct production of modular units, patterned superhydrophobic-superhydrophilic (SH-SL) surfaces have emerged as promising platforms for scalable manufacturing of microscale modular units to develop functional tissues designed by the bottom-up approach. In this sense, and inspired by the Lotus effect, the present work aims at the production of freestanding (FS) stratificated micromembranes based on polyl- lysine (PLL) and alginate (ALG) biopolymers through the Layer-by-Layer (LbL) methodology. For this purpose, initially microscale SH-SL surfaces with different geometric shapes were developed. Subsequently, alginate hydrogels were formed in situ by the standing droplet method in the SL areas that served as a sacrificial template to the production of freestanding membranes by sequential deposition of electrolytes through electrostatic interactions. Regarding the deposition conditions of the polymers, in the zeta potential analysis, the charges of each compound were verified, while the quartz microbalance (QCM-D) showed the electrostatic interaction between PLL and ALG. ATR-FTIR analysis confirmed the presence of polymers in the resulting membrane. After detachment, the resulting membranes crosslinked with genipin (GnP) to improve mechanical properties to promote cell adhesion and proliferation. Biological assays with human umbilical vein endothelial cells (HUVECs) and human adipose stem cells (hASCs) showed that the crosslinked [PLL / ALG]100 membranes show cellular viability.A engenharia modular de tecidos visa mimetizar a complexidade do tecido nativo com arquiteturas 3D bem definidas e interações sinérgicas de várias linhas celulares através da geração de unidades modulares funcionais repetidas que serão montadas em um tecido funcional. Esses blocos modulares devem exibir características microestruturais específicas para imitar a arquitetura complexa de tecidos nativos. Para a produção direta de unidades modulares, as superfícies superhidrofóbicas-superhidrofílicas (SHSL) padronizadas surgiram como plataformas promissoras para uma fabricação escalável de unidades modulares à microescala para desenvolver tecidos funcionais projetados pela abordagem bottom-up. Neste sentido, e inspirado no efeito de Lotus, o presente trabalho visa a produção de micromembranas autónomas estratificadas baseadas nos biopolímeros poli-llisina (PLL) e alginato (ALG) através da metodologia Layer-by-Layer (LbL). Para este propósito, inicialmente foram desenvolvidas superfícies SH-SL padronizadas à microescala com diferentes formas geométricas. Posteriormente, hidrogéis de alginato foram formados in situ pelo método standing droplet nas áreas SL que serviram de template de sacrifício para a produção de membranas autónomas pela deposição sequencial dos polieletrólitos através de interações electrostáticas. Relativamente às condições de deposição dos polímeros, na análise do potencial zeta verificaram-se as cargas de cada composto, enquanto que a microbalança de quartzo (QCM-D) evidenciou a interação eletrostática entre a PLL e o ALG. A análise por ATR-FTIR, confirmou a presença dos polímeros na membrana resultante. Após o destaque, as membranas forma reticuladas com genipina (GnP) para melhorar as propriedades mecânicas a fim de promover a adesão e proliferação celular. Ensaios biológicos com human umbilical vein endotelial cells (HUVECs) e human adipose stem cells (hASCs) evidenciaram que as membranas de [PLL/ALG]100 reticuladas apresentam viabilidade celular.Mestrado em Materiais e Dispositivos Biomédico

Shortened Poly-N-Acetyl Glucosamine (sNAG) Nanofibers Induce Rapid Vascular Assembly in 3-Dimensional Microtissue Spheroids

Tissue vascularization and integration with host circulation remains a key barrier to the successful translation of engineered tissues into clinically relevant therapies. Current efforts to implant large engineered structures are limited by insufficient delivery of oxygen and nutrients, and waste removal. Work presented in this thesis focus on the use of a naturally derived nanofiber for improving molecular interactions between vascular endothelial cells and smooth muscle cells for application to vascular bioengineering. We hypothesize optimization of instructive interactions between vascular cell types can improve formation of microtissue spheroids for application to vascular bioengineering. Toward this goal, I use shortened poly-N-acetyl glucosamine (sNAG) nanofibers to facilitate co‐assembly of pre-vascularized network formation within microtissue spheroids. To gain initial insights into the potential use of sNAG as an instructive biomaterial for vascular tissue regeneration applications, UCB-EPCs, ADSC-VSMCs, and AoAFs were co‐cultured in cell‐aggregates in the presence of sNAG or other known effectors of vascular assembly. Immunofluorescence analysis by confocal microscopy revealed a strong angiogenic effect on EC-only monocultures, which resulted in EC sprout formation, and remodeling in 2D Matrigel assays. When grown in 3D, sNAG nanofibers induced UCB-EPCs migration and increased levels of hPECAM-1 expression, indicative of a fully differentiated EC phenotype. Heterotypic cell cultures show that sNAG nanofibers elicit synthesis of proteins associated with vascular wall assembly and stabilization. An interesting finding of these analyses was that expression of collagen type‐4 was significantly increased in our sNAG treated microtissue spheroids. This increase was greatest in areas of heterotypic cell association, highlighting the importance of cross talk between EPC‐ECs and ADSC‐VSMCs in stimulating synthesis of vascular wall components. Collectively, our preliminary studies suggest that sNAG nanofibers may provide an instructive, biocompatible matrix for assembly of prevascularized microtissue spheroids

Tissue Engineering and Regenerative Medicine 2019:The Role of Biofabrication-A Year in Review

Despite its relative youth, biofabrication is unceasingly expanding by assimilating the contributions from various disciplinary areas and their technological advances. Those developments have spawned the range of available options to produce structures with complex geometries while accurately manipulating and controlling cell behavior. As it evolves, biofabrication impacts other research fields, allowing the fabrication of tissue models of increased complexity that more closely resemble the dynamics of living tissue. The recent blooming and evolutions in biofabrication have opened new windows and perspectives that could aid the translational struggle in tissue engineering and regenerative medicine (TERM) applications. Based on similar methodologies applied in past years' reviews, we identified the most high-impact publications and reviewed the major concepts, findings, and research outcomes in the context of advancement beyond the state-of-the-art in the field. We first aim to clarify the confusion in terminology and concepts in biofabrication to therefore introduce the striking evolutions in three-dimensional and four-dimensional bioprinting of tissues. We conclude with a short discussion on the future outlooks for innovation that biofabrication could bring to TERM research