A nanobiosensor for dynamic single cell analysis during microvascular self-organization.

Among the promising methods for repairing or replacing tissue defects in the human body and the hottest research topics in medical science today are regenerative medicine and tissue engineering. On the other hand, nanotechnology has been expanded into different areas of regenerative medicine and tissue engineering due to its essential benefits in improving performance in various fields. Nanotechnology, a helpful strategy in tissue engineering, offers new solutions to unsolved problems. Especially considering the excellent physicochemical properties of nanoscale structures, their application in regenerative medicine has been gradually developed, and a lot of research has been conducted in this field. In this regard, various nanoscale structures, including nanofibers, nanosheets, nanofilms, nano-clays, hollow spheres, and different nanoparticles, have been developed to advance nanotechnology strategies with tissue repair goals. Here, we comprehensively review the application of the mentioned nanostructures in constructing nanocomposite scaffolds for regenerative medicine and tissue engineering. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Diagnostic Tools > Biosensing.

Single-Cell Imaging

Novel therapies resulting from regenerative medicine and tissue engineering technology may offer new hope for patients with injuries, end-stage organ failure, degenerative disorders and many other clinical issues. Currently, patients suffering from diseased and injured organs are treated with transplanted organs. However, there is a shortage of donor organs that is worsening yearly as the population ages and new cases of organ failure increase. Scientists in the field of regenerative medicine and tissue engineering are now applying the principles of cell transplantation, material science, and bioengineering to construct biological substitutes that can restore and maintain normal function in diseased and injured tissues. In addition, the stem cell field is a rapidly advancing part of regenerative medicine, and new discoveries in this field create new options for this type of therapy. For example, new types of stem cells, such as amniotic fluid and placental stem cells, that can circumvent the ethical issues associated with embryonic stem cells have been discovered. The process of somatic cell nuclear transfer and the creation of induced pluripotent cells provide still other potential sources of stem cells for cell-based tissue engineering applications. While stem cells are still in the research phase, some therapies arising from tissue engineering endeavors that make use of autologous, adult cells have already entered the clinical setting, indicating that regenerative medicine holds much promise for the future.

Regenerative medicine and tissue engineering are now expanding to practically all healthcare fields, including cardiac, corneal, nerve, vascular and liver tissue engineering and regeneration [Bracaglia LG, 2017]. Favorable government regulatory framework, continuous technology advancements and increasing research funding drive the market for alternative regenerative medicine therapies. Global tissue engineering market is expected to reach USD 11.53 billion by 2022, according to a new report by Grand View Research, Inc (2016). Tissue engineering combines cells, biomaterials and growth factors to support and regenerate the biological tissues. Three key components are needed for tissue engineering – cells, growth factors and scaffolds. Whereas cells produce tissue matrix, scaffold provides the appropriate environment for cells to effectively accomplish their missions. The function of growth factors is to facilitate and promote cells to regenerate new tissue [Spurlin JW 3rd, 2017]. Medical company ilaya® uses tissue engineering and regenerative medicine approaches in the clinical applications, such as treatment of critical sized bone defects and avascular necrosis (AVN) . METHODS. To fabricate 3D-TEBE (three-dimensional tissue-engineered bone equivalent) we used devitalized allogeneic/xenogeneic bone (blocks and chips) seeded with autologous cultured cells: bone marrow-derived MSCs alone or in mix with periosteum progenitor cells (PPCs, 3:1), or with PPCs and peripheral blood endothelial progenitor cells (EPCs, 3:1:1) depending on bone defect size. Quality assurance of cell seeded 3D-TEBE was done via combined staining with FDA/PI and histological analysis (H&E). New bone formation was assessed by the radiographic examination. RESULTS. Eighteen patients had the AVN III/IV by Steinberg, 11 of them had cystic bone reconstruction sites. In 8 patients, AVN corresponded to stage IV/V with subchondral fracture and deformation of the femoral head (26 patients in total). In AVN patients bone structure restoration was observed in 94.4% and endoprosthesis surgery was no more actual for 90.9%. Bone integrity was successfully restored in 39 combat related casualties (42 critical sized bone defects). FDA/PI staining, and histological analysis of 3D-TEBE samples showed their regular seeding with viable cells. Histological analysis of 3D-TEBE biopsies 3 months after transplantation showed their intensive remodeling and immature bone tissue formation. Thereof, the 3D-TEBE transplantation is able to restore bone integrity and greatly reduce, as compared with conventional cure methods, patient’s rehabilitation period. Conclusions. The 3D-TEBE transplantation is able to restore bone integrity and greatly reduce, as compared with conventional cure methods, patient’s rehabilitation period.

Mesenchymal stem cells derived from bone marrow favor tumor cell growth in vivo

Introduction: regenerative medicine and tissue engineering are emerging disciplines that seek to restore the function of damaged tissues and organs through technological innovations. These areas combine biology, engineering, and medicine to develop solutions that improve patients' quality of life. In this context, scaffolding technologies, stem cell engineering, and bioprinting stand out as key tools for tissue repair and organ regeneration.Development: scaffolds are three-dimensional structures that provide physical support for cell growth and tissue formation. They can be designed with biocompatible materials that mimic the properties of natural tissue, facilitating integration with the body. Stem cell engineering, on the other hand, allows for the extraction and differentiation of cells with regenerative potential, which is crucial for repairing damage to specific tissues. Bioprinting, an innovative technique, uses 3D printers to create complex cellular structures, enabling the manufacture of personalized tissues and artificial organs. These technologies have shown promising results in preclinical and clinical studies, offering new hope in the treatment of degenerative diseases, traumatic injuries, and birth defects.Conclusions: innovations in scaffolding technologies, stem cell engineering, and bioprinting are opening up new possibilities for tissue and organ repair and regeneration. As these technologies continue to evolve, it is critical to address the associated ethical and regulatory challenges to ensure their safe and effective implementation in clinical practice.

Tissue engineering is an exciting field that has arisen amidst projections of revolutionizing reconstructive surgery. Fabricating tissue with a patient-specific, three-dimensional geometry from a cocktail of autologous cells, growth factors, and biocompatible/biodegradable polymers would address donor site morbidity concerns, alleviate tissue shortages, and improve patient quality of life. Achieving these rather lofty goals requires the collaborative effort of scientists, engineers, and surgeons in recognizing and addressing the unique concerns of engineered tissue. Tissue engineering is an exciting field that has arisen amidst projections of revolutionizing reconstructive surgery. Fabricating tissue with a patient-specific, three-dimensional geometry from a cocktail of autologous cells, growth factors, and biocompatible/biodegradable polymers would address donor site morbidity concerns, alleviate tissue shortages, and improve patient quality of life. Achieving these rather lofty goals requires the collaborative effort of scientists, engineers, and surgeons in recognizing and addressing the unique concerns of engineered tissue. One of the most important design constraints to providing clinically translatable engineered tissue is the development of a patent microvascular network with properly structured geometry within the tissue engineered constructs. Microvascular networks control the mass transport of nutrients, ensure tissue viability, control tissue differentiation, and allow long-term tissue maintenance. It has been shown that cells cannot survive greater then 200 μm from a blood supply. It is also recognized that angiogenesis occurring in an unregulated fashion produces undesirable results. This is most recognized in the oftstudied tumor angiogenesis; however, little is known about the formation, growth-kinetics, and architecture of microvascular networks in tissue engineered constructs. A complete understanding of angiogenesis in any system is impossible with current assays and imaging modalities. Many techniques have been developed to study angiogenesis and microvascular architecture. These methods include in vitro gels, animal preparations, vascular casts, micro-CT, histology, and immunohistochemistry. Microvascular networks are complex, exhibiting wide variation among environments and can be greatly complicated due to various pathologies. These assays require broad assumptions about or oversimplification of the networks. Angiogenesis can be adequately understood only with a high resolution, threedimensional, quantifiable assay. Result images allow measurement of many parameters, including vascular network density, vessel diameters, void space, and tortuosity. We have developed a novel, sophisticated method with resolution to the endothelial cell level that allows visualization and quantitation of microvascular networks in three dimensions. Briefly, tissue is excised, cryofixed, and six micron serial sections are cut on a cryostat. Each section is immunostained for CD-31, an endothelial cell specific antigen, and stained sections are imaged in 2D using a CCD camera. Immunohistochemistry used in combination with microscopy allows high resolution images of antigenically distinct features of tissue. Although quantitative data can be obtained using other methods, only immunohistochemistry allows quantitation at the cellular level while maintaining the relationship between stained cells and overall tissue morphology. The 2D images are aligned using automated image registration techniques and volume rendered to produce a 3D, quantifiable image of the microvascular networks within the tissue. journals/ijps/vol1n1/3d.rm Quantitative 3D Analysis Of Microvascular Networks In Tissue Engineering 2 of 3 Currently, we are applying this technique to the study of angiogenesis in model tissue engineered constructs. The movie depicts capillary invasion into a fibrin gel following implantation of a model tissue engineered construct within a rat model. The image is 1200 x 500 x 240 μm with 1 μm resolution. Vessels and endothelial cells are pseudo-colored red and the fibrin white. Vessels can be seen growing within the fibrin and endothelial cells along the periphery of the fibrin indicate the leading edge of angiogenesis. The inosculation mechanisms by which surgical free flaps (the tissue engineering gold standard) establish and maintain a patent vascular network are also being studied. This work will lead to a better understanding of angiogenesis in tissue engineering and will contribute to the development of clinically useful tissue engineered products.

Anhydride-containing oligomer-crosslinked gelatin microparticles: crosslinking process understanding using design of experiments

Regenerative medicine is a rapidly evolving multidisciplinary, translational research enterprise whose explicit purpose is to advance technologies for the repair and replacement of damaged cells, tissues, and organs. Scientific progress in the field has been steady and expectations for its robust clinical application continue to rise. The major thesis of this review is that the pharmacological sciences will contribute critically to the accelerated translational progress and clinical utility of regenerative medicine technologies. In 2007, we coined the phrase "regenerative pharmacology" to describe the enormous possibilities that could occur at the interface between pharmacology, regenerative medicine, and tissue engineering. The operational definition of regenerative pharmacology is "the application of pharmacological sciences to accelerate, optimize, and characterize (either in vitro or in vivo) the development, maturation, and function of bioengineered and regenerating tissues." As such, regenerative pharmacology seeks to cure disease through restoration of tissue/organ function. This strategy is distinct from standard pharmacotherapy, which is often limited to the amelioration of symptoms. Our goal here is to get pharmacologists more involved in this field of research by exposing them to the tools, opportunities, challenges, and interdisciplinary expertise that will be required to ensure awareness and galvanize involvement. To this end, we illustrate ways in which the pharmacological sciences can drive future innovations in regenerative medicine and tissue engineering and thus help to revolutionize the discovery of curative therapeutics. Hopefully, the broad foundational knowledge provided herein will spark sustained conversations among experts in diverse fields of scientific research to the benefit of all.

Angiogenesis, the formation of new capillaries from existing ones, is a fundamental process in regenerative medicine and tissue engineering. While it is known to be affected by circadian rhythms in vivo, its peripheral regulation within the vasculature and the role it performs in regulating the interplay between vascular cells have not yet been investigated. Peripheral clocks within the vasculature have been described in the endothelium and in smooth muscle cells. However, to date, scarce evidence has been presented regarding pericytes, a perivascular cell population deeply involved in the regulation of angiogenesis and vessel maturation, as well as endothelial function and homeostasis. More crucially, pericytes are also a promising source of cells for cell therapy and tissue engineering. Here, we established that human primary pericytes express key circadian genes and proteins in a rhythmic fashion upon synchronization. Conversely, we did not detect the same patterns in cultured endothelial cells. In line with these results, pericytes’ viability was disproportionately affected by circadian cycle disruption, as compared to endothelial cells. Interestingly, endothelial cells’ rhythm could be induced following exposure to synchronized pericytes in a contact co-culture. We propose that this mechanism could be linked to the altered release/uptake pattern of lactate, a known mediator of cell-cell interaction which was specifically altered in pericytes by the knockout of the key circadian regulator Bmal1. In an angiogenesis assay, the maturation of vessel-like structures was affected only when both endothelial cells and pericytes did not express Bmal1, indicating a compensation system. In a 3D tissue engineering scaffold, a synchronized clock supported a more structured organization of cells around the scaffold pores, and a maturation of vascular structures. Our results demonstrate that pericytes play a critical role in regulating the circadian rhythms in endothelial cells, and that silencing this system disproportionately affects their pro-angiogenic function. Particularly, in the context of tissue engineering and regenerative medicine, considering the effect of circadian rhythms may be critical for the development of mature vascular structures and to obtain the maximal reparative effect.

Mesenchymal stem cells (MSCs) have generated a great deal of interest in clinical situations, due principally to their potential use in regenerative medicine and tissue engineering applications. However, the therapeutic application of MSCs remains limited, unless the favorable effects of MSCs for tumor growth in vivo and the long-term safety of the clinical applications of MSCs can be understood more thoroughly. In this study, MSCs derived from human adipose tissues (hASCs) together with tumor cells were transplanted subcutaneously or intracranially into BALB/c nude mice to observe tumor outgrowth. The results indicated that hASCs with H460 or U87MG cells promoted tumor growth in nude mice. Our histopathological analyses indicated that the co-injection of tumor cells with hASCs exerted no influence on the formation of intratumoral vessels. Co-culture of tumor cells with hASCs or the addition of conditioned medium (CM) from hASCs effected an increase in the proliferation of H460 or U87MG cells. Co-injection of hASCs with tumor cells effected an increase in tumor cell viability in vivo, and also induced a reduction in apoptotic cell death. CM from hASCs inhibited hydrogen peroxide-induced cell death in H460 or U87MG cells. These findings indicated that MSCs could favor tumor growth in vivo. Thus, it is necessary to conduct a study concerning the long-term safety of this technique before MSCs can be used as therapeutic tools in regenerative medicine and tissue engineering.

Regenerative medicine and tissue engineering potential of mesenchymal stem cells exosomes-derived microRNAs.

In recent decades, regenerative medicine has merited substantial attention from scientific and research communities. One of the essential requirements for this new strategy in medicine is the production of biocompatible and biodegradable scaffolds with desirable geometric structures and mechanical properties. Despite such promise, it appears that regenerative medicine is the last field to embrace green, or environmentally-friendly, processes, as many traditional tissue engineering materials employ toxic solvents and polymers that are clearly not environmentally friendly. Scaffolds fabricated from plant proteins (for example, zein, soy protein, and wheat gluten), possess proper mechanical properties, remarkable biocompatibility and aqueous stability which make them appropriate green biomaterials for regenerative medicine applications. The use of plant-derived proteins in regenerative medicine has been especially inspired by green medicine, which is the use of environmentally friendly materials in medicine. In the current review paper, the literature is reviewed and summarized for the applicability of plant proteins as biopolymer materials for several green regenerative medicine and tissue engineering applications.

Bio-printing is a trending technology in the field of tissue engineering and regenerative medicine, creating complex three-dimensional structures. The advancements in bio-printing, including the steps and materials used in bio-printers, have been highlighted. Various bio-printing techniques such as micro-extrusion, inkjet printing, and laser-based approaches are discussed. Moreover, the roles of biomaterials and their importance in bio-printing cannot be overstated. Characteristics such as cell viability, adhesion, differentiation, biodegradability, and biocompatibility are paramount in ensuring the success of bio-printed tissues. Additionally, the interdisciplinary nature of bio-printing research fosters collaborations between biologists, engineers, material scientists, and medical professionals. This synergy facilitates the development of innovative bio-printing technologies and accelerates their translation into clinical applications. Furthermore, the evolution of bio-printing technology is not only reshaping medical practice but also opening new frontiers in scientific exploration. By mimicking the complex architectures and functionalities of native tissues, bio-printed constructs serve as valuable tools for studying tissue development, disease mechanisms, and drug responses. The ability to recreate physiologically relevant microenvironments in vitro provides researchers with unprecedented insights into cellular behavior and tissue dynamics. The bio-printing represents a transformative approach in tissue engineering and regenerative medicine, offering unparalleled opportunities for tissue fabrication, disease modeling, and drug discovery. As research in this field continues to progress, we can anticipate even more remarkable breakthroughs that will revolutionize healthcare and biomedical research.

Adult stem cells, especially isolated from bone marrow, have been extensively investigated in recent years. Studies focus on their multiple plasticity oftransdifferentiating into various cell lineages and on their potential in cellular therapy in regenerative medicine. In many cases, there is the need for tissue engineering manipulation. Among the different approaches of stem cells tissue engineering, microencapsulation can immobilize stem cells to provide a favorable microenvironment for stem cells survival and functioning. Furthermore, microencapsulated stem cells are immunoisolated after transplantation. We show that one intraperitoneal injection of microencapsulated bone marrow stem cells can prolong the survival of liver failure rat models with 90% of the liver removed surgically. In addition to transdifferentiation, bone marrow stem cells can act as feeder cells. For example, when coencapsulated with hepatocytes, stem cells can increase the viability and function of the hepatocytes in vitro and in vivo.