Recent Methods for Modifying Mechanical Properties of Tissue-Engineered Scaffolds for Clinical Applications

Integrating Computational and Biological Hemodynamic Approaches to Improve Modeling of Atherosclerotic Arteries

Atherosclerosis is the primary cause of cardiovascular disease, resulting in mortality, elevated healthcare costs, diminished productivity, and reduced quality of life for individuals and their communities. This is exacerbated by the limited understanding of its underlying causes and limitations in current therapeutic interventions, highlighting the need for sophisticated models of atherosclerosis. This review critically evaluates the computational and biological models of atherosclerosis, focusing on the study of hemodynamics in atherosclerotic coronary arteries. Computational models account for the geometrical complexities and hemodynamics of the blood vessels and stenoses, but they fail to capture the complex biological processes involved in atherosclerosis. Different in vitro and in vivo biological models can capture aspects of the biological complexity of healthy and stenosed vessels, but rarely mimic the human anatomy and physiological hemodynamics, and require significantly more time, cost, and resources. Therefore, emerging strategies are examined that integrate computational and biological models, and the potential of advances in imaging, biofabrication, and machine learning is explored in developing more effective models of atherosclerosis.

Additive and Lithographic Manufacturing of Biomedical Scaffold Structures Using a Versatile Thiol-Ene Photocurable Resin

Additive and lithographic manufacturing technologies using photopolymerisation provide a powerful tool for fabricating multiscale structures, which is especially interesting for biomimetic scaffolds and biointerfaces. However, most resins are tailored to one particular fabrication technology, showing drawbacks for versatile use. Hence, we used a resin based on thiol-ene chemistry, leveraging its numerous advantages such as low oxygen inhibition, minimal shrinkage and high monomer conversion. The resin is tailored to applications in additive and lithographic technologies for future biofabrication where fast curing kinetics in the presence of oxygen are required, namely 3D inkjet printing, digital light processing and nanoimprint lithography. These technologies enable us to fabricate scaffolds over a span of six orders of magnitude with a maximum of 10 mm and a minimum of 150 nm in height, including bioinspired porous structures with controlled architecture, hole-patterned plates and micro/submicro patterned surfaces. Such versatile properties, combined with noncytotoxicity, degradability and the commercial availability of all the components render the resin as a prototyping material for tissue engineers.

Advances in Wireless, Batteryless, Implantable Electronics for Real-Time, Continuous Physiological Monitoring

This review summarizes recent progress in developing wireless, batteryless, fully implantable biomedical devices for real-time continuous physiological signal monitoring, focusing on advancing human health care. Design considerations, such as biological constraints, energy sourcing, and wireless communication, are discussed in achieving the desired performance of the devices and enhanced interface with human tissues. In addition, we review the recent achievements in materials used for developing implantable systems, emphasizing their importance in achieving multi-functionalities, biocompatibility, and hemocompatibility. The wireless, batteryless devices offer minimally invasive device insertion to the body, enabling portable health monitoring and advanced disease diagnosis. Lastly, we summarize the most recent practical applications of advanced implantable devices for human health care, highlighting their potential for immediate commercialization and clinical uses.

Effect of GelMA Hydrogel Properties on Long-Term Encapsulation and Myogenic Differentiation of C2C12 Spheroids

Skeletal muscle regeneration and engineering hold great promise for the treatment of various muscle-related pathologies and injuries. This research explores the use of gelatin methacrylate (GelMA) hydrogels as a critical component for encapsulating cellular spheroids in the context of muscle tissue engineering and regenerative applications. The preparation of GelMA hydrogels at various concentrations, ranging from 5% to 15%, was characterized and correlated with their mechanical stiffness. The storage modulus was quantified and correlated with GelMA concentration: 6.01 ± 1.02 Pa (5% GelMA), 75.78 ± 6.67 Pa (10% GelMA), and 134.69 ± 7.93 Pa (15% GelMA). In particular, the mechanical properties and swelling capacity of GelMA hydrogels were identified as key determinants affecting cell sprouting and migration from C2C12 spheroids. The controlled balance between these factors was found to significantly enhance the differentiation and functionality of the encapsulated spheroids. Our results highlight the critical role of GelMA hydrogels in orchestrating cellular dynamics and processes within a 3D microenvironment. The study demonstrates that these hydrogels provide a promising scaffold for the long-term encapsulation of spheroids while maintaining high biocompatibility. This research provides valuable insights into the design and use of GelMA hydrogels for improved muscle tissue engineering and regenerative applications, paving the way for innovative approaches to muscle tissue repair and regeneration.

Electrospun Scaffolds Enriched with Nanoparticle-Associated DNA: General Properties, DNA Release and Cell Transfection

Biomaterial-mediated, spatially localized gene delivery is important for the development of cell-populated scaffolds used in tissue engineering. Cells adhering to or penetrating into such a scaffold are to be transfected with a preloaded gene that induces the production of secreted proteins or cell reprogramming. In the present study, we produced silica nanoparticles-associated pDNA and electrospun scaffolds loaded with such nanoparticles, and studied the release of pDNA from scaffolds and cell-to-scaffold interactions in terms of cell viability and pDNA transfection efficacy. The pDNA-coated nanoparticles were characterized with dynamic light scattering and transmission electron microscopy. Particle sizes ranging from 56 to 78 nm were indicative of their potential for cell transfection. The scaffolds were characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, stress-loading tests and interaction with HEK293T cells. It was found that the properties of materials and the pDNA released vary, depending on the scaffold's composition. The scaffolds loaded with pDNA-nanoparticles do not have a pronounced cytotoxic effect, and can be recommended for cell transfection. It was found that (pDNA-NPs) + PEI9-loaded scaffold demonstrates good potential for cell transfection. Thus, electrospun scaffolds suitable for the transfection of inhabiting cells are eligible for use in tissue engineering.

The Concept of Scaffold-Guided Bone Regeneration for the Treatment of Long Bone Defects: Current Clinical Application and Future Perspective

The treatment of bone defects remains a challenging clinical problem with high reintervention rates, morbidity, and resulting significant healthcare costs. Surgical techniques are constantly evolving, but outcomes can be influenced by several parameters, including the patient's age, comorbidities, systemic disorders, the anatomical location of the defect, and the surgeon's preference and experience. The most used therapeutic modalities for the regeneration of long bone defects include distraction osteogenesis (bone transport), free vascularized fibular grafts, the Masquelet technique, allograft, and (arthroplasty with) mega-prostheses. Over the past 25 years, three-dimensional (3D) printing, a breakthrough layer-by-layer manufacturing technology that produces final parts directly from 3D model data, has taken off and transformed the treatment of bone defects by enabling personalized therapies with highly porous 3D-printed implants tailored to the patient. Therefore, to reduce the morbidities and complications associated with current treatment regimens, efforts have been made in translational research toward 3D-printed scaffolds to facilitate bone regeneration. Three-dimensional printed scaffolds should not only provide osteoconductive surfaces for cell attachment and subsequent bone formation but also provide physical support and containment of bone graft material during the regeneration process, enhancing bone ingrowth, while simultaneously, orthopaedic implants supply mechanical strength with rigid, stable external and/or internal fixation. In this perspective review, we focus on elaborating on the history of bone defect treatment methods and assessing current treatment approaches as well as recent developments, including existing evidence on the advantages and disadvantages of 3D-printed scaffolds for bone defect regeneration. Furthermore, it is evident that the regulatory framework and organization and financing of evidence-based clinical trials remains very complex, and new challenges for non-biodegradable and biodegradable 3D-printed scaffolds for bone regeneration are emerging that have not yet been sufficiently addressed, such as guideline development for specific surgical indications, clinically feasible design concepts for needed multicentre international preclinical and clinical trials, the current medico-legal status, and reimbursement. These challenges underscore the need for intensive exchange and open and honest debate among leaders in the field. This goal can be addressed in a well-planned and focused stakeholder workshop on the topic of patient-specific 3D-printed scaffolds for long bone defect regeneration, as proposed in this perspective review.