Scaffolds for Peripheral Nerve Regeneration, the Importance of In Vitro and In Vivo Studies for the Development of Cell-Based Therapies and Biomaterials: State of the Art

Human adult peripheral nerve injuries are a high incidence clinical problem that greatly affects patients’ quality of life. Although peripheral nervous system has intrinsic regenerative capacity, this occurs in an incomplete or poorly functional manner. When a nerve fiber loses its continuity with consequent damage of the basal lamina tubes, axon spontaneous regeneration is disorganized and mismatched. These phenomena translate in an inadequate nerve functional recovery and consequent musculoskeletal incapacity. Nerve grafts still remain the gold standard in peripheral injuries treatment. However, this approach contains its disadvantages such as the necessity of primary surgery to harvest the autografts, loss of a functional nerve, donor site morbidity and longer surgery procedures. Therefore, biomaterials and tissue engineering can provide efficient resources and alternatives to nerve injury repair not only by the development of biocompatible structures but also, introducing neurotrophic factors and cellular systems to stimulate optimum clinical outcome. In this chapter, a comprehensive state-of-the art picture of tissue-engineered nerve grafts scaffolds, their application in nerve regeneration along with latest advances in peripheral nerve repair and future perspectives will be discussed, including our own large experience in this field of knowledge

Metabolomic and Proteomic Analysis of the Mesenchymal Stem Cells’ Secretome

Mesenchymal stem cells (MSCs) are multipotent stromal cells with a strong potential in human regenerative medicine due to their ability to renew themselves and differentiate into various specialized cell types under certain physiological or experimental conditions. MSCs secrete a broad spectrum of autocrine and paracrine factors (MSCs’ secretome) that could exert significant effects on cells in their vicinity. MSCs have been clinically tested and have displayed a great potential in the treatment of bone/cartilage fractures and disorders, diabetes, cardiovascular diseases and immune, neurodegenerative and inflammatory diseases. The therapeutic efficacy of MSCs was initially attributed to their multipotent character and ability to engraft and differentiate at the site of injury. However, in recent years, it has been revealed that either undifferentiated or differentiated MSCs’ secretome plays an important role in the therapeutic potential of MSCs. The deciphering of the composition of MSCs’ secretome through proteomic and metabolic analyses and implementation of certain advanced analytical (nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), chromatography, etc.) and immunological methods could contribute to the understanding of the mechanisms underlying the therapeutic effects of MSCs

Synovia-Derived Mesenchymal Stem Cell Application in Musculoskeletal Injuries: A Review

Musculoskeletal injuries impact millions of people globally and affect their health and well-being as well as of their companion and athletic animals. Soft-tissue injuries represent almost half of these and are associated with unorganized scar tissue formation and long time-depending healing processes. Cell-based therapeutic strategies have been developed in the past decades aiming at the treatment and reversion of such disorders. Stem cells are fairly appealing in the field, being a responsive undifferentiated population, with ability to self-renew and differentiate into different lineages. Mesenchymal stem cells (MSCs) can be obtained from several adult tissues, including the synovial membrane. Synovia-derived MSCs can be found in individuals of any age and are associated to intrinsic regenerative processes, through both paracrine and cell-to-cell interactions, thus, contributing to hosts’ healing capacity. Studies have demonstrated the potential benefit of synovia-derived MSCs in these regenerative processes in both human and veterinary medicine. The purpose of this chapter is to review the literature regarding SM-MSC therapies applied to musculoskeletal disorders, in both human and veterinary medicine

is it time to move forward?

Funding: This research was supported by Projects PEst-OE/AGR/UI0211/2011 from FCT, and COMPETE 2020, from ANI – Projetos ID&T Empresas em Copromoção, by the project “insitu.Biomas – Reinvent biomanufacturing systems by using an usability approach for in situ clinic temporary implants fabrication” with the reference POCI-01-0247-FEDER-017771, by the project “Print-on-Organs – Engineering bioinks and processes for direct printing on organs” with the reference POCI-01-0247-FEDER-033877, and by the project “Bone2Move – Development of “in vivo” experimental techniques and modelling methodologies for the evaluation of 4D scafolds for bone defect in sheep model: an integrative research approach” with the reference POCI-01-0145-FEDER-031146. Mariana Vieira Branquinho (SFRH/BD/146172/2019), Ana Catarina Sousa (SFRH/BD/146689/2019), and Rui Damásio Alvites (SFRH/BD/116118/2016), acknowledge FCT, for financial support.INTRODUCTION: Central airway obstruction (CAO) represents a pathological condition that can lead to airflow limitation of the trachea, main stem bronchi, bronchus intermedius or lobar bronchus. MAIN BODY: It is a common clinical situation consensually considered under-diagnosed. Management of patients with CAO can be difficult and deciding on the best treatment approach represents a medical challenge. This work intends to review CAO classifications, causes, treatments and its therapeutic limitations, approaching benign and malign presentations. Three illustrative cases are further presented, supporting the clinical problem under review. CONCLUSION: Management of CAO still remains a challenge. The available options are not always effective nor free from complications. A new generation of costume-tailored airway stents, associated with stem cell-based therapy, could be an option in specific clinical situations.publishersversionpublishe

Mesenchymal Stem Cells (MSCs) as a potential therapeutic Strategy in COVID-19 Patients: Literature Research

In 2019, an outbreak of an unknown coronavirus – SARS-CoV-2 – responsible for COVID-19 disease, was first reported in China, and evolved into a pandemic of huge dimensions and raised serious concerns for global health. The number of critical cases continues to increase dramatically, while vaccines and specific treatments are not yet available. There are several strategies currently being studied for the treatment of adverse symptoms of COVID-19, that encompass Acute Lung Injury (ALI)/Acute Respiratory Distress Syndrome (ARDS), extensive pulmonary inflammation, cytokine storm, and pulmonary edema, due to virus-induced pneumonia.info:eu-repo/semantics/publishedVersio

The in vitro mechanical properties of small diameter Poly(vinyl) alcohol hydrogel (PVA) plus dextran (Dx) based vascular grafts.

Introduction The production of artificial vascular grafts of small diameter is a fluorescing line of investigation. PVA is a biomaterial that has been used for several biomedical applications and nowadays as a vascular graft. However the mechanical properties were never characterized in vitro. It was our objective to produce small diameter PVA grafts and characterize their physical and mechanical properties for posterior evaluation in a large animal model. Methods PVA vascular grafts were prepared by the physical reticulation technique freeze/thawing plus annealing and were made with 5 cm of length and an internal diameter of 5 mm. PVA was associated to dextran in 1% concentration. For the physical properties were addressed tests to determine wettability and electrical charge; and the mechanical properties were characterized according to the ISO standard 7198:1998 using burst pressure and dynamic mechanical analysis. Results and discussion Graft wettability was determined by contact angle (56.5º±0.2) and the surface was considered hydrophilic facilitating endothelial cell adhesion. Burst pressure evidenced the resistance of the graft to a maximum value of inner pressure (3.8±0.3 bar) compatible to the documented values for human large arteries. The elasticity of grafts is important due to the pulsatile nature of the flow in arterial conduits. The young modulus is a reflexion of that elasticity and the value for this artificial graft was 9.8x104±4.8x103 Pa which is close to the documented value for arteries. Conclusions The results of physical and mechanical characterization make this vascular graft a successful candidate for further in vivo characterization in a large animal model

Application of artificial vascular polyvinyl alcohol hydrogel grafts in sheep - our experience to date.

Researchers developed this project according with the tasks originally planned, so far focusing their research activities in the biocompatibility and functionality of vascular implants. The biocompatibility was studied by following the ISO standard 10993-6 for evaluation of medical devices through the evaluation and grading of inflammation caused by implants placed subcutaneously. The implants were placed in sheep and collected randomly at different time points of the experimental period and subsequently processed histologically and classified according to Annex E to the standard mentioned above. The functionality of vascular implants has been evaluated to date by replacement of segments of the carotid by ePTFE implants with 5 cm long and 4 mm in diameter, coated or not with cultured stem cells. The deployment of these prostheses has been performed in carotid arteries of sheep and their functional performance measured by vascular ultrasound in Doppler and B mode by measuring parameters such as: peak systolic / diastolic blood flow velocity, vascular diameters at implantation and at the periphery of these. These measurements are performed at various time points of the experiment were folloed by euthanasia of sheep and immediately sample collection for the implementation of techniques like immunohistochemistry, morphometry and scanning electronic microscopy. Complications were observed throughout the experimental period include the formation of thrombi after at the transition implantcarotid region and vascular dilatation as the most frequent, respectively, in periods of short-and long-term experiment

Olfactory Mucosa Mesenchymal Stem Cells and Biomaterials: A New Combination to Regenerative Therapies after Peripheral Nerve Injury

The peripheral nerve injury after trauma is a common occurrence in both human and veterinary medicine and has severe consequences for the survival and quality of life of the patients. Despite the continuous efforts and the creation of diverse medical and surgical techniques, the harmful effects of this type of injury are far from being overcome. Regenerative medicine has been growing in the scientific milieu as a new therapeutic approach for different situations. Among the cell-based therapies explored, the mesenchymal stem cells are evidenced by their features, versatility and potential applications. The olfactory mucosa mesenchymal stem cells, components of the olfactory system and identified in the lamina propria, were newly identified and are still undergoing characterization, appearing as a new promise in the regenerative therapy of several tissues but with special emphasis on the nervous system in general and the peripheral nervous system in particular, for which they appear to have special regenerative aptitude

Spray Drying: An Overview

Spray drying is a well-known method of particle production which comprises the transformation of a fluid material into dried particles, taking advantage of a gaseous hot drying medium, with clear advantages for the fabrication of medical devices. In fact, it is quite common the production of microspheres and microcapsules designed for drug delivery systems. This review describes the different stages of the mechanism of the spray-drying process: atomization, droplet-to-particle conversion and particle collection. In particular, this work addresses the diversity of available atomizers, the drying kinetics and the importance of the configuration of the drying chamber, and the efficiency of the collection devices. The final properties of the dried products are influenced by a variety of factors, namely the spray dryer design, the feed characteristics and the processing parameters. The impact of those variables in optimizing both the spray-drying process and the synthesis of dried particles with desirable characteristics is discussed. The scalability of this manufacturing process in obtaining dried particles in submicron-to-micron scale favors a variety of applications within the food, chemical, polymeric, pharmaceutical, biotechnology and medical industries

Clinical Application of Macroporous Ceramic to Promote Bone Healing in Veterinary Clinical Cases

Autogenous cancellous bone is the most effective material in promoting rapid healing and still considered the “gold standard” for evaluation of bone graft substitutes. The harvesting process to collect autologous bone is associated with complications and its availability is limited. Allogenic bone is another alternative with osteoconductive properties, and it act as a structural graft when applied in defects of long bones, but some disadvantages are also associated. The development of the bone grafts substitutes has gained tremendous popularity over the last two decades. Osteoconductive materials act as scaffolds were cells from the surrounding tissues with osteogenic capacities can lay new bone, and may be produced using different types of agents, such as bone products, ceramics, bioactive glasses, collagen, polymers, and composites. Bonelike® is produced by the incorporation of P2O5–CaO glass-based system within a hydroxyapatite matrix. Bonelike® Poro consists of polygonal granules with 2000–2800 μm and 4000–5600 μm of diameter with pore sizes range from 100 to 400 μm. This chapter will focus on the different techniques were this ceramic synthetic bone substitute was used to promote bone regeneration with special attention in both experimental and clinical cases of veterinary orthopaedics in dogs and cats, horses and ruminants, including results obtained with Bonelike®