Search Results for human tissues

The field of bioprinting is a subset of additive manufacturing (AM) that is rapidly expanding to meet the needs of regenerative medicine and tissue engineering. Bioprinting encompasses a broad spectrum of issues, from cell expansion and novel bioink development to cell/stem cell printing, from organoid-based tissue organization to bioprinting of human-scale tissue structures, and from building cell/tissue/organ-on-a-chip to biomanufacturing of multicellular engineered living systems. This article focuses on two challenges regarding bioprinting: bioinks and crosslinking. It describes the methods for characterizing the performance of bioink formulations and the effectiveness of crosslinking strategies. The topics covered include modalities of bioprinting, characteristics of bioink, rheological properties of bioink sols, rheological measurements, mathematical models of bioink rheology, postfabrication polymer network mechanics, mechanical properties of crosslinked bioinks, and printability of bioinks. Finally, specific strategies used for crosslinking bioinks, as well as some emerging strategies to further improve bioinks and their crosslinking, are summarized.

Microvalve jetting, with its advantages of low cost, ease of operation, high printing speed, and ability to process living cells with high viability, has been primarily used for fabricating high-throughput drug-screening models, in vitro cellular structures for fundamental cell biology research, and cell-laden structures for regenerating tissues or organs in the human body after disease or trauma. This article provides an overview of microvalve jetting of biomaterials, including operational parameters. The jetting technologies covered are inkjet printing, microvalve jetting, and laser-assisted jetting. The parameters covered include nozzle size (nozzle inner diameter), pneumatic pressure, valve-opening time, and printing speed of microvalve jetting. Subsequently, the article discusses biomaterials for microvalve jetting in terms of biomaterial definition, required properties for a suitable biomaterial, currently used biomaterials, and cells and cellular structures. Additionally, applications of microvalve jetting in biomedical engineering are presented, which include cellular and RNA analysis, high-throughput drug screening, and tissue engineering.

Hydroxyapatite (HA) is one of the most popular materials in tissue scaffold engineering due to its similarity to the nature of human bone; it accounts for more than half of the total weight of the latter. Selective laser sintering (SLS) is an additive manufacturing method that is used in producing tissue engineering parts from HA feedstocks. This article provides a brief overview of the process itself, along with a detailed review of HA-based tissue engineering applications using SLS. Discussion on the various polymer composites is presented. A detailed overview of selected publications on HA-based SLS studies is listed, which provides insight regarding technical aspects of processing HA powder feedstocks.

In the field of medical device development and testing, the corrosion of metallic parts can lead to significant adverse effects on the biocompatibility of the device. This article describes the mechanisms of metal and alloy biocompatibility. It reviews the response of implant metals and particulate materials to corrosion. The effect of metal ions from an implanted device on the human body is also discussed. The article concludes with information on the possible cancer-causing effects of metallic biomaterials.

This article discusses the mechanisms of metal and alloy biocompatibility. It provides information on early testing and experience with metals in medical device applications. The article describes the response of implant and particulate materials to severe corrosion. It provides a description of metal binding and its effects on metabolic processes. Hypersensitive responses to metal ions are also reviewed. The article concludes with a discussion on the possible cancer-causing effects of metallic biomaterials.

Due to its layer-by-layer process, 3D printing enables the formation of complex geometries using multiple materials. Three-dimensional printing for bone tissue engineering is called bioprinting and refers to the use of material-transfer processes for patterning and assembling biologically relevant materials, molecules, cells, tissues, and biodegradable biomaterials with a prescribed organization to accomplish one or more biological functions. Currently, 3D bioprinting constructs can be classified into two categories: acellular and cellular. This article introduces and discusses these two approaches based on the suitable materials for these constructs and the fabrication processes used to manufacture them. The materials are grouped into polymers, metals, and hydrogels. The article also summarizes the commonly used 3D printing techniques for these materials, as well as cell types used for various applications. Lastly, current challenges in tissue engineering are discussed.

Ceramics are used widely in a number of different clinical applications in the human body. This article provides a brief history of the bioceramics field and discusses the classification of bioceramics. These include bioinert ceramics, bioactive ceramics, and bioresorbable ceramics. The article describes third-generation bioceramics, classified by Hench and Polak, such as silicate-substituted hydroxyapatite and bone morphogenic protein-carrying calcium phosphate coatings. It reviews several examination methods used to test the biocompatibility of ceramics, namely, biosafety testing, biofunctionality testing, bioactivity testing, and bioresorbability testing.

This article discusses alginate/gelatin-based bioinks in 3D bioprinting applications, providing a summary of the most relevant previous work in the field. It presents advanced compositions to enhance functionality and/or optimize hydrogels for 3D bioprinting. The article discusses advanced printing techniques for alginate/gelatin-based bioinks.

This article focuses on the pneumatic extrusion-based system for biomaterials. It provides an overview of additive manufacturing (AM) processes, followed by sections covering steps and major approaches for the 3D bioprinting process. Then, the article discusses the types, processes, advantages, limitations, and applications of AM technology and extrusion-based approaches. Next, it provides information on the research on extrusion-based printing. Finally, the article provides a comparison of the extrusion-based approach with other approaches.

The use of 3D bioprinting techniques has contributed to the development of novel cellular patterns and constructs in vitro, ex vivo, and even in vivo. There are three main bioprinting techniques: inkjet printing, extrusion printing (also known as bioextrusion), laser-induced forward transfer (LIFT) printing, which is also known as modified LIFT printing, matrix-assisted pulsed-laser evaporation direct write, and laser-based printing (laser-assisted bioprinting, or biological laser printing). This article provides an overview of the LIFT process, including the LIFT process introduction, different implementations, jetting dynamics, printability phase diagrams, and printing process simulations. Additionally, materials involved during LIFT are introduced in terms of bioink materials and energy-absorbing layer materials. Also, the printing of single cells and 2D and 3D constructs is introduced, showcasing the current state of the art with the ultimate goal for tissue- and organ-printing applications.

This article discusses several aspects of biocompatibility of polymers, including the selection of a suitable polymer, specific use of a material, contact of polymer on body site, and duration of the contact. It describes the factors influencing the biological response of the polymer from a biocompatibility perspective. These include raw materials, the manufacturing process, cleaning and sterilization processes, and biodegradation and biostability. The article reviews the general testing methods of polymers, such as chemical, mechanical and thermal. It concludes with a section on the guidance, provided by the regulatory authorities, on the biocompatibility testing of polymers and polymer-containing devices that can aid in selecting the right analysis.

The human internal environment plays a vital role in the friction and wear of implants and prosthetic devices. This article describes the tribological/wear behavior of implants. It discusses the classification of active tribological pairs, namely, amphiarthosis joints and diarthosis joints. The article details the classification of total knee replacement, depending on the type of mechanical stability, including nonconstrained knee replacement, semiconstrained knee replacement, and constrained knee replacement. It also discusses the classifications of passive tribological pairs, namely, total disc replacement in the spine, dental implants, and temporomandibular joint. It describes the various testing methods for characterizing the implant materials used in hip, knee, spine, and dental applications. The article also describes the typical standards used for testing wear behavior of tribological pairs, namely, hip-wear simulation standards, knee-wear simulation standards, and spinal disc-wear simulation standards.

This article discusses the state of the art in the 3D bioprinting field. It examines the printability of protein-based biopolymers and provides key printing parameters, along with a brief description of the main current 3D bioprinting approaches. The article presents some studies investigating 3D bioprinting of naturally derived proteins for the production of structurally and functionally biomimetic scaffolds, which create a microenvironment for cells resembling that of the native tissues. It describes key structural proteins processed in the form of hydrogels, such as collagen, silk, fibrin, and others such as elastin, decellularized matrix, and Matrigel (Corning), which are used as biomaterials.

Bridging the gap between education and medical practice, centralized hospital-based 3D printing, or what is termed point-of-care (POC) manufacturing, has been rapidly growing in the United States as well as internationally. This article provides insights into the considerations and the current workflow of creating 3D-printed anatomical models at the POC. Case studies are introduced to show the complex range of anatomical models that can be produced while also exploring how patient care benefits. It describes the advanced form of communication in medicine. The advantages as well as pitfalls of using the patient-specific 3D-printed models at the POC are addressed, demonstrating the fundamental knowledge needed to create 3D-printed anatomical models through POC manufacturing.

This article outlines the selection criteria for choosing an implant material for biomedical devices in orthopedic, dental, soft-tissue, and cardiovascular applications. It details the development of various implants, such as metallic, ceramic, and polymeric implants. The article discusses specific problems associated with implant manufacturing processes and the consequent compromises in the properties of functionally graded implants. It describes the manufacturing of the functionally-graded hip implant by using the LENS process. The article reviews four different types of tissue responses to the biomaterial. It discusses the testing methods of implant failure, such as in vitro and in vivo assessment of tissue compatibility.

This article begins with a description of extrusion-based bioprinting for tissue scaffold fabrication. It also examines various extrusion-based bioprinting processes and related tissue scaffolding strategies, presents the selection criteria of various bioinks with various polymers and their printed scaffolds for applications in tissue engineering and regenerative medicines, and provides future research recommendations to address the shortcomings and issues found in current extrusion-based bioprinting processes.

The biocompatibility of a material relates to its immunological response, toxicity profile, and ability to integrate with surrounding tissue without undesirable local or systemic effects on a patient. This article underscores the transformation of the medical device design ecosystem engaged as an integral part of the device ecosystem. It discusses the applications of biomaterials, including orthopedic, cardiovascular, ophthalmic, and dental applications. The article describes four major categories of biomaterials such as metals, polymers, glass and ceramics, and composites. A discussion on natural materials, nanomaterials, and stem cells is also provided. The article concludes with examples of biomaterials applications, such as endovascular devices, knee implants, and neurostimulation.

Bioprinting has been advancing in the field of tissue engineering as the process for fabricating scaffolds, making use of additive manufacturing technologies. In situ bioprinting (also termed intraoperative bioprinting) is a promising solution to address the limitations of conventional bioprinting approaches. This article discusses the main approaches and technologies for in situ bioprinting. It provides a brief overview of the bioprinting pipeline, highlighting possible solutions to improve currently used approaches. Additionally, case studies of in situ bioprinting are provided and in situ bioprinting future perspectives are discussed.

This article provides an overview of additive manufacturing (AM) methods, the three-dimensional (3D)-AM-related market, and the medical additive manufactured applications. It focuses on the current scenario and future developments related to metal AM for medical applications. The discussion covers the benefits of using 3D-AM technology in the medical field, provides specific examples of medical devices fabricated by AM, reviews trends in metal implant development using AM, and presents future prospects for the development of novel high-performance medical devices via metal 3D-additive manufacturing.