Functional characterization of 3D contractile smooth muscle tissues generated using a unique microfluidic 3D bioprinting technology

Development of Biocompatible 3D-Printed Artificial Blood Vessels through Multidimensional Approaches

Within the human body, the intricate network of blood vessels plays a pivotal role in transporting nutrients and oxygen and maintaining homeostasis. Bioprinting is an innovative technology with the potential to revolutionize this field by constructing complex multicellular structures. This technique offers the advantage of depositing individual cells, growth factors, and biochemical signals, thereby facilitating the growth of functional blood vessels. Despite the challenges in fabricating vascularized constructs, bioprinting has emerged as an advance in organ engineering. The continuous evolution of bioprinting technology and biomaterial knowledge provides an avenue to overcome the hurdles associated with vascularized tissue fabrication. This article provides an overview of the biofabrication process used to create vascular and vascularized constructs. It delves into the various techniques used in vascular engineering, including extrusion-, droplet-, and laser-based bioprinting methods. Integrating these techniques offers the prospect of crafting artificial blood vessels with remarkable precision and functionality. Therefore, the potential impact of bioprinting in vascular engineering is significant. With technological advances, it holds promise in revolutionizing organ transplantation, tissue engineering, and regenerative medicine. By mimicking the natural complexity of blood vessels, bioprinting brings us one step closer to engineering organs with functional vasculature, ushering in a new era of medical advancement.

A high-throughput 3D cantilever array to model airway smooth muscle hypercontractility in asthma

Asthma is often characterized by tissue-level mechanical phenotypes that include remodeling of the airway and an increase in airway tightening, driven by the underlying smooth muscle. Existing therapies only provide symptom relief and do not improve the baseline narrowing of the airway or halt progression of the disease. To investigate such targeted therapeutics, there is a need for models that can recapitulate the 3D environment present in this tissue, provide phenotypic readouts of contractility, and be easily integrated into existing assay plate designs and laboratory automation used in drug discovery campaigns. To address this, we have developed DEFLCT, a high-throughput plate insert that can be paired with standard labware to easily generate high quantities of microscale tissues in vitro for screening applications. Using this platform, we exposed primary human airway smooth muscle cell-derived microtissues to a panel of six inflammatory cytokines present in the asthmatic niche, identifying TGF-β1 and IL-13 as inducers of a hypercontractile phenotype. RNAseq analysis further demonstrated enrichment of contractile and remodeling-relevant pathways in TGF-β1 and IL-13 treated tissues as well as pathways generally associated with asthma. Screening of 78 kinase inhibitors on TGF-β1 treated tissues suggests that inhibition of protein kinase C and mTOR/Akt signaling can prevent this hypercontractile phenotype from emerging, while direct inhibition of myosin light chain kinase does not. Taken together, these data establish a disease-relevant 3D tissue model for the asthmatic airway, which combines niche specific inflammatory cues and complex mechanical readouts that can be utilized in drug discovery efforts.

An Engineered Living Intestinal Muscle Patch Produces Macroscopic Contractions that can Mix and Break Down Artificial Intestinal Contents

The intestinal muscle layers execute various gut wall movements to achieve controlled propulsion and mixing of intestinal content. Engineering intestinal muscle layers with complex contractile function is critical for developing bioartificial intestinal tissue to treat patients with short bowel syndrome. Here, the first demonstration of a living intestinal muscle patch capable of generating three distinct motility patterns and displaying multiple digesta manipulations is reported. Assessment of contractility, cellular morphology, and transcriptome profile reveals that successful generation of the contracting muscle patch relies on both biological factors in a serum-free medium and environmental cues from an elastic electrospun gelatin scaffold. By comparing gene-expression patterns among samples, it is shown that biological factors from the medium strongly affect ion-transport activities, while the scaffold unexpectedly regulates cell-cell communication. Analysis of ligandreceptor interactome identifies scaffold-driven changes in intercellular communication, and 78% of the upregulated ligand-receptor interactions are involved in the development and function of enteric neurons. The discoveries highlight the importance of combining biomolecular and biomaterial approaches for tissue engineering. The living intestinal muscle patch represents a pivotal advancement for building functional replacement intestinal tissue. It offers a more physiological model for studying GI motility and for preclinical drug discovery.

Cell-contact-mediated assembly of contractile airway smooth muscle rings

Microtissues in the shape of toroidal rings provide an ideal geometry to better represent the structure and function of the airway smooth muscle present in the small airways, and to better understand diseases such as asthma. Here, polydimethylsiloxane devices consisting of a series of circular channels surrounding central mandrels are used to form microtissues in the shape of toroidal rings by way of the self-aggregation and -assembly of airway smooth muscle cell (ASMC) suspensions. Over time, the ASMCs present in the rings become spindle-shaped and axially align along the ring circumference. Ring strength and elastic modulus increase over 14 d in culture, without significant changes in ring size. Gene expression analysis indicates stable expression of mRNA for extracellular matrix-associated proteins, including collagen I and lamininsα1 andα4 over 21 d in culture. Cells within the rings respond to TGF-β1 treatment, leading to dramatic decreases in ring circumference, with increases in mRNA and protein levels for extracellular matrix and contraction-associated markers. These data demonstrate the utility of ASMC rings as a platform for modeling diseases of the small airways such as asthma.

Hydrogels for Tissue Engineering: Addressing Key Design Needs Toward Clinical Translation

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3D Printing: Applications in Tissue Engineering, Medical Devices, and Drug Delivery

The gemstone of 3-dimensional (3D) printing shines up from the pyramid of additive manufacturing. Three-dimensional bioprinting technology has been predicted to be a game-changing breakthrough in the pharmaceutical industry since the last decade. It is fast evolving and finds its seats in a variety of domains, including aviation, defense, automobiles, replacement components, architecture, movies, musical instruments, forensic, dentistry, audiology, prosthetics, surgery, food, and fashion industry. In recent years, this miraculous manufacturing technology has become increasingly relevant for pharmaceutical purposes. Computer-aided drug (CAD) model will be developed by computer software and fed into bioprinters. Based on material inputs, the printers will recognize and produce the model scaffold. Techniques including stereolithography, selective laser sintering, selective laser melting, material extrusion, material jetting, inkjet-based, fused deposition modelling, binder deposition, and bioprinting expedite the printing process. Distinct advantages are rapid prototyping, flexible design, print on demand, light and strong parts, fast and cost-effective, and environment friendly. The present review gives a brief description of the conceptional 3-dimensional printing, followed by various techniques involved. A short note was explained about the fabricating materials in the pharmaceutical sector. The beam of light is thrown on the various applications in the pharma and medical arena.

Natural Hydrogel-Based Bio-Inks for 3D Bioprinting in Tissue Engineering: A Review

Three-dimensional (3D) printing is well acknowledged to constitute an important technology in tissue engineering, largely due to the increasing global demand for organ replacement and tissue regeneration. In 3D bioprinting, which is a step ahead of 3D biomaterial printing, the ink employed is impregnated with cells, without compromising ink printability. This allows for immediate scaffold cellularization and generation of complex structures. The use of cell-laden inks or bio-inks provides the opportunity for enhanced cell differentiation for organ fabrication and regeneration. Recognizing the importance of such bio-inks, the current study comprehensively explores the state of the art of the utilization of bio-inks based on natural polymers (biopolymers), such as cellulose, agarose, alginate, decellularized matrix, in 3D bioprinting. Discussions regarding progress in bioprinting, techniques and approaches employed in the bioprinting of natural polymers, and limitations and prospects concerning future trends in human-scale tissue and organ fabrication are also presented.

Bioinks and Bioprinting Strategies for Skeletal Muscle Tissue Engineering

Skeletal muscles play important roles in critical body functions and their injury or disease can lead to limitation of mobility and loss of independence. Current treatments result in variable functional recovery, while reconstructive surgery, as the gold-standard approach, is limited due to donor shortage, donor-site morbidity, and limited functional recovery. Skeletal muscle tissue engineering (SMTE) has generated enthusiasm as an alternative solution for treatment of injured tissue and serves as a functional disease model. Recently, bioprinting has emerged as a promising tool for recapitulating the complex and highly organized architecture of skeletal muscles at clinically relevant sizes. Here, skeletal muscle physiology, muscle regeneration following injury, and current treatments following muscle loss are discussed, and then bioprinting strategies implemented for SMTE are critically reviewed. Subsequently, recent advancements that have led to improvement of bioprinting strategies to construct large muscle structures, boost myogenesis in vitro and in vivo, and enhance tissue integration are discussed. Bioinks for muscle bioprinting, as an essential part of any bioprinting strategy, are discussed, and their benefits, limitations, and areas to be improved are highlighted. Finally, the directions the field should expand to make bioprinting strategies more translational and overcome the clinical unmet needs are discussed.

Cell-Seeded Biomaterial Scaffolds: The Urgent Need for Unanswered Accelerated Angiogenesis

One of the most arduous challenges in tissue engineering is neovascularization, without which there is a lack of nutrients delivered to a target tissue. Angiogenesis should be completed at an optimal density and within an appropriate period of time to prevent cell necrosis. Failure to meet this challenge brings about poor functionality for the tissue in comparison with the native tissue, extensively reducing cell viability. Prior studies devoted to angiogenesis have provided researchers with some biomaterial scaffolds and cell choices for angiogenesis. For example, while most current angiogenesis approaches require a variety of stimulatory factors ranging from biomechanical to biomolecular to cellular, some other promising stimulatory factors have been underdeveloped (such as electrical, topographical, and magnetic). When it comes to choosing biomaterial scaffolds in tissue engineering for angiogenesis, key traits rush to mind including biocompatibility, appropriate physical and mechanical properties (adhesion strength, shear stress, and malleability), as well as identifying the appropriate biomaterial in terms of stability and degradation profile, all of which may leave essential trace materials behind adversely influencing angiogenesis. Nevertheless, the selection of the best biomaterial and cells still remains an area of hot dispute as such previous studies have not sufficiently classified, integrated, or compared approaches. To address the aforementioned need, this review article summarizes a variety of natural and synthetic scaffolds including hydrogels that support angiogenesis. Furthermore, we review a variety of cell sources utilized for cell seeding and influential factors used for angiogenesis with a concentrated focus on biomechanical factors, with unique stimulatory factors. Lastly, we provide a bottom-to-up overview of angiogenic biomaterials and cell selection, highlighting parameters that need to be addressed in future studies.

Emerging Technologies in Multi-Material Bioprinting

Bioprinting, within the emerging field of biofabrication, aims at the fabrication of functional biomimetic constructs. Different 3D bioprinting techniques have been adapted to bioprint cell-laden bioinks. However, single-material bioprinting techniques oftentimes fail to reproduce the complex compositions and diversity of native tissues. Multi-material bioprinting as an emerging approach enables the fabrication of heterogeneous multi-cellular constructs that replicate their host microenvironments better than single-material approaches. Here, bioprinting modalities are reviewed, their being adapted to multi-material bioprinting is discussed, and their advantages and challenges, encompassing both custom-designed and commercially available technologies are analyzed. A perspective of how multi-material bioprinting opens up new opportunities for tissue engineering, tissue model engineering, therapeutics development, and personalized medicine is offered.

3D Bioprinting of Biomimetic Bilayered Scaffold Consisting of Decellularized Extracellular Matrix and Silk Fibroin for Osteochondral Repair

Recently, three-dimensional (3D) bioprinting technology is becoming an appealing approach for osteochondral repair. However, it is challenging to develop a bilayered scaffold with anisotropic structural properties to mimic a native osteochondral tissue. Herein, we developed a bioink consisting of decellularized extracellular matrix and silk fibroin to print the bilayered scaffold. The bilayered scaffold mimics the natural osteochondral tissue by controlling the composition, mechanical properties, and growth factor release in each layer of the scaffold. The in vitro results show that each layer of scaffolds had a suitable mechanical strength and degradation rate. Furthermore, the scaffolds encapsulating transforming growth factor-beta (TGF-β) and bone morphogenetic protein-2 (BMP-2) can act as a controlled release system and promote directed differentiation of bone marrow-derived mesenchymal stem cells. Furthermore, the in vivo experiments suggested that the scaffolds loaded with growth factors promoted osteochondral regeneration in the rabbit knee joint model. Consequently, the biomimetic bilayered scaffold loaded with TGF-β and BMP-2 would be a promising strategy for osteochondral repair.

Applications of 3D Bio-Printing in Tissue Engineering and Biomedicine

In recent years, 3D bio-printing technology has developed rapidly and become an advanced bio-manufacturing technology. At present, 3D bio-printing technology has been explored in the fields of tissue engineering, drug testing and screening, regenerative medicine and clinical disease research and has achieved many research results. Among them, the application of 3D bio-printing technology in tissue engineering has been widely concerned by researchers, and it contributing many breakthroughs in the preparation of tissue engineering scaffolds. In the future, it is possible to print fully functional tissues or organs by using 3D bio-printing technology which exhibiting great potential development prospects in th applications of organ transplantation and human body implants. It is expected to solve thebiomedical problems of organ shortage and repair of damaged tissues and organs. Besides,3Dbio-printing technology will benefit human beings in more fields. Therefore, this paper reviews the current applications, research progresses and limitations of 3D bio-printing technology in biomedical and life sciences, and discusses the main printing strategies of 3D bio-printing technology. And, the research emphases, possible development trends and suggestions of the application of 3D bio-printing are summarized to provide references for the application research of 3D bio-printing.

Microvascular Tissue Engineering-A Review

Tissue engineering and regenerative medicine have come a long way in recent decades, but the lack of functioning vasculature is still a major obstacle preventing the development of thicker, physiologically relevant tissue constructs. A large part of this obstacle lies in the development of the vessels on a microscale-the microvasculature-that are crucial for oxygen and nutrient delivery. In this review, we present the state of the art in the field of microvascular tissue engineering and demonstrate the challenges for future research in various sections of the field. Finally, we illustrate the potential strategies for addressing some of those challenges.

Emergence of FRESH 3D printing as a platform for advanced tissue biofabrication

In tissue engineering, an unresolved challenge is how to build complex 3D scaffolds in order to recreate the structure and function of human tissues and organs. Additive manufacturing techniques, such as 3D bioprinting, have the potential to build biological material with unprecedented spatial control; however, printing soft biological materials in air often results in poor fidelity. Freeform Reversible Embedding of Suspended Hydrogels (FRESH) is an embedded printing approach that solves this problem by extruding bioinks within a yield-stress support bath that holds the bioinks in place until cured. In this Perspective, we discuss the challenges of 3D printing soft and liquid-like bioinks and the emergence for FRESH and related embedded printing techniques as a solution. This includes the development of FRESH and embedded 3D printing within the bioprinting field and the rapid growth in adoption, as well as the advantages of FRESH printing for biofabrication and the new research results this has enabled. Specific focus is on the customizability of the FRESH printing technique where the chemical composition of the yield-stress support bath and aqueous phase crosslinker can all be tailored for printing a wide range of bioinks in complex 3D structures. Finally, we look ahead at the future of FRESH printing, discussing both the challenges and the opportunities that we see as the biofabrication field develops.

Tools, techniques, and future opportunities for characterizing the mechanobiology of uterine myometrium

The myometrium is the smooth muscle layer of the uterus that generates the contractions that drive processes such as menstruation and childbirth. Aberrant contractions of the myometrium can result in preterm birth, insufficient progression of labor, or other difficulties that can lead to maternal or fetal complications or even death. To investigate the underlying mechanisms of these conditions, the most common model systems have conventionally been animal models and human tissue strips, which have limitations mostly related to relevance and scalability, respectively. Myometrial smooth muscle cells have also been isolated from patient biopsies and cultured in vitro as a more controlled experimental system. However, in vitro approaches have focused primarily on measuring the effects of biochemical stimuli and neglected biomechanical stimuli, despite the extensive evidence indicating that remodeling of tissue rigidity or excessive strain is associated with uterine disorders. In this review, we first describe the existing approaches for modeling human myometrium with animal models and human tissue strips and compare their advantages and disadvantages. Next, we introduce existing in vitro techniques and assays for assessing contractility and summarize their applications in elucidating the role of biochemical or biomechanical stimuli on human myometrium. Finally, we conclude by proposing the translation of "organ on chip" approaches to myometrial smooth muscle cells as new paradigms for establishing their fundamental mechanobiology and to serve as next-generation platforms for drug development.

Recent progress in extrusion 3D bioprinting of hydrogel biomaterials for tissue regeneration: a comprehensive review with focus on advanced fabrication techniques

Over the last decade, 3D bioprinting has received immense attention from research communities to bridge the divergence between artificially engineered tissue constructs and native tissues.

Next Stage Approach to Tissue Engineering Skeletal Muscle

Large-scale muscle injury in humans initiates a complex regeneration process, as not only the muscular, but also the vascular and neuro-muscular compartments have to be repaired. Conventional therapeutic strategies often fall short of reaching the desired functional outcome, due to the inherent complexity of natural skeletal muscle. Tissue engineering offers a promising alternative treatment strategy, aiming to achieve an engineered tissue close to natural tissue composition and function, able to induce long-term, functional regeneration after in vivo implantation. This review aims to summarize the latest approaches of tissue engineering skeletal muscle, with specific attention toward fabrication, neuro-angiogenesis, multicellularity and the biochemical cues that adjuvate the regeneration process.