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

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

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

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®

Peripheral nerve injury and axonotmesis: State of the art and recent advances

Peripheral nerve lesions are frequent occurrences in both human and animal patients, leading to important physiological and labor complications that affect the quality of life of those who suffer the injury. More severe injuries are often associated with poor nerve regeneration and inadequate functional recovery, even with early medical and surgical interventions. Peripheral nerve crush lesions are frequent and, therefore, an experimental lesion paradigm widely used in researches involving nerve injury models and therapies for its resolution. In recent years, many studies have focused on innovative approaches to peripheral nerve treatment after crush injuries with more or less success. This review addresses the theme of peripheral nerve injury, with a special focus on the axonotmesis lesion, its etiology, pathophysiological mechanisms, methods of functional evaluation and regenerative processes, therapeutic options and corresponding recent advances

MSCs Conditioned Media and Umbilical Cord Blood Plasma Metabolomics and Composition.

Human mesenchymal stem cells (hMSCs) from umbilical cord (UC) blood (UCB) and matrix are tested clinically for a variety of pathologies but in vitro expansion using culture media containing fetal bovine serum (FBS) is essential to achieve appropriate cell numbers for clinical use. Human UCB plasma (hUCBP) can be used as a supplement for hMSCs culture, since UCB is rich in soluble growth factors and due to worldwide increased number of cryopreserved UCB units in public and private banks, without the disadvantages listed for FBS. On the other hand, the culture media enriched in growth factors produced by these hMSCs in expansion (Conditioned medium--CM) can be an alternative to hMSCs application. The CM of the hMSCs from the UC might be a better therapeutic option compared to cell transplantation, as it can benefit from the local tissue response to the secreted molecules without the difficulties and complications associated to the engraftment of the allo- or xeno-transplanted cells. These facts drove us to know the detailed composition of the hUCBP and CM, by 1H-NMR and Multiplexing LASER Bead Technology. hUCBP is an adequate alternative for the FBS and the CM and hUCBP are important sources of growth factors, which can be used in MSCs-based therapies. Some of the major proliferative, chemotactic and immunomodulatory soluble factors (TGF-β, G-CSF, GM-CSF, MCP-1, IL-6, IL-8) were detected in high concentrations in CM and even higher in hUCBP. The results from 1H-NMR spectroscopic analysis of CM endorsed a better understanding of hMSCs metabolism during in vitro culture, and the relative composition of several metabolites present in CM and hUCBP was obtained. The data reinforces the potential use of hUCBP and CM in tissue regeneration and focus the possible use of hUCBP as a substitute for the FBS used in hMSCs in vitro culture

Biomaterials and Cellular Systems at the Forefront of Peripheral Nerve Regeneration

Peripheral nerve injuries remain a common clinical complication, and currently available therapies present significant limitations, often resulting in poor and suboptimal outcomes. Despite significant developments in microsurgical approaches in the last decades, no effective treatment options have been disclosed. Current research focuses on the optimization of such microsurgical techniques and on their combination with other pro-regenerative factors, such as mesenchymal stem cells or biomaterials. Mesenchymal stem cells present a remarkable capacity for bioactive molecule production that modulates inflammatory and regenerative processes, stimulating peripheral nerve regeneration. In parallel, efforts have been directed towards the development of biomaterial nerve guidance channels and nerve conduits. These biomaterials have been optimized in terms of biodegradability, ability to release bioactive factors, incorporation of cellular agents, and internal matrix architecture (to enable cellular migration and mimic native tissue morphology and to generate and bear specific electrical activity). The current literature review presents relevant advances in the development of mesenchymal stem cell and biomaterial-based therapeutic approaches aiming at the peripheral nerve tissue regeneration in diverse lesion scenarios, also exploring the advances achieved by our research group in this field in recent years

Dextrin hydrogel loaded with a macroporous Bonelike® scaffold and dental pulp stem cells for critical-sized defect repair

Regeneration of severe bone defects remains a challenge. A formulation of synthetic glass-reinforced hydroxyapatite bone substitute, Bonelike® Poro (BL®P), 250500 µm-diameter, with a dextrin-based hydrogel (HG), further loaded with human dental pulp stem cells (hDPSCs) with osteogenic differentiation ability, was tested for the management of critical-sized defects in an ovine model. Morphology, calcium release, and mechanical strength of HG + BL®P were analyzed. Then, BL®P, HG + BL®P, and 106 hDPSCs-loaded HG + BL®P were implanted in ovine critical-sized 14 mm-diameter calvaria defects. Bone samples were collected after 3 and 6 weeks for histological and micro-CT analysis. BL®P exhibits a suitable porous size for cell ingrowth, from the nm (>200 nm) to the µm (5 µm) range. The addition of BL®P granules to the HG resulted in increased compressive elastic modulus and ultimate tensile strength. The mildly acidic nature of the HG contributed to a faster dissolution of granules. In vivo results confirmed the HG suitability as a carrier, providing better defect filling, easy handling, and injectability of BL®P without compromising new bone formation nor biocompatibility. The HG + BL®P formulations can successfully regenerate critical-sized defects; however, addition of hDPSCs did not significantly enhance new bone formation under these conditions. Granular BL®P provides an effective alternative to autologous grafts. The HG acts as a biocompatible carrier of granular bone substitutes and cells, conferring injectability and cohesivity.Alexandra Machado and Isabel Pereira were supported by the grants SFRH/BD/132000/2017 and UMINHO/BI/131/2018 respectively, from Portuguese Foundation for Science and Technology (FCT), Portugal. The authors acknowledge the funding from FEDER and NORTE 2020 through the project no. 003262 titled “iBONE therapies: advanced solutions for bone regeneration”. This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte 2020 - Programa Operacional Regional do Norte. The participation of Isabel Pires, Justina Prada, Luís Maltez and José Eduardo Pereira was funded by the projects UIDB/CVT/00772/2020 and LA/P/0059/2020 supported by FCT. The participation of Rui Alvites, Ana Catarina Sousa, Mariana Branquinho, Ana Rita Caseiro, Sílvia Santos Pedrosa and Ana Colette Maurício was funded by Projects PEst-OE/AGR/UI0211/2011, UIDB/CVT/00772/2020 and LA/P/0059/2020. Mariana Vieira Branquinho (SFRH/BD/146172/2019) and Ana Catarina Sousa (SFRH/BD/146689/2019) acknowledge FCT, for financial support.info:eu-repo/semantics/publishedVersio