Tunable injectable alginate-based hydrogel for cell therapy in Type 1 Diabetes Mellitus

Islet transplantation has the potential of reestablishing naturally-regulated insulin production in Type 1 diabetic patients. Nevertheless, this procedure is limited due to the low islet survival after transplantation and the lifelong immunosuppression to avoid rejection. Islet embedding within a biocompatible matrix provides mechanical protection and a physical barrier against the immune system thus, increasing islet survival. Alginate is the preferred biomaterial used for embedding insulin-producing cells because of its biocompatibility, low toxicity and ease of gelation. However, alginate gelation is poorly controlled, affecting its physicochemical properties as an injectable biomaterial. Including different concentrations of the phosphate salt Na2HPO4 in alginate hydrogels, we can modulate their gelation time, tuning their physicochemical properties like stiffness and porosity while maintaining an appropriate injectability. Moreover, these hydrogels showed good biocompatibility when embedding a rat insulinoma cell line, especially at low Na2HPO4 concentrations, indicating that these hydrogels have potential as injectable biomaterials for Type 1 Diabetes Mellitus treatment

Advances in the slow freezing cryopreservation of microencapsulated cells

Over the past few decades, the use of cell microencapsulation technology has been promoted for a wide range of applications as sustained drug delivery systems or as cells containing biosystems for regenerative medicine. However, difficulty in their preservation and storage has limited their availability to healthcare centers. Because the preservation in cryogenic temperatures poses many biological and biophysical challenges and that the technology has not been well understood, the slow cooling cryopreservation, which is the most used technique worldwide, has not given full measure of its full potential application yet. This review will discuss the different steps that should be understood and taken into account to preserve microencapsulated cells by slow freezing in a successful and simple manner. Moreover, it will review the slow freezing preservation of alginate-based microencapsulated cells and discuss some recommendations that the research community may pursue to optimize the preservation of microencapsulated cells, enabling the therapy translate from bench to the clinic

Development, characterization and sterilisation of Nanocellulose-alginate-(hyaluronic acid)- bioinks and 3D bioprinted scaffolds for tissue engineering

3D-bioprinting is an emerging technology of high potential in tissue engineering (TE), since it shows effective control over scaffold fabrication and cell distribution. Biopolymers such as alginate (Alg), nanofibrillated cellulose (NC) and hyaluronic acid (HA) offer excellent characteristics for use as bioinks due to their excellent biocompatibility and rheological properties. Cell incorporation into the bioink requires sterilisation assurance, and autoclave, β-radiation and γ-radiation are widely used sterilisation techniques in biomedicine; however, their use in 3D-bioprinting for bioinks sterilisation is still in their early stages. In this study, different sterilisation procedures were applied on NC-Alg and NC-Alg-HA bioinks and their effect on several parameters was evaluated. Results demonstrated that NC-Alg and NC-Alg-HA bioinks suffered relevant rheological and physicochemical modifications after sterilisation; yet, it can be concluded that the short cycle autoclave is the best option to sterilise both NC-Alg based cell-free bioinks, and that the incorporation of HA to the NC-Alg bioink improves its characteristics. Additionally, 3D scaffolds were bioprinted and specifically characterized as well as the D1 mesenchymal stromal cells (D1-MSCs) embedded for cell viability analysis. Notably, the addition of HA demonstrates better scaffold properties, together with higher biocompatibility and cell viability in comparison with the NC-Alg scaffolds. Thus, the use of MSCs containing NC-Alg based scaffolds may become a feasible tissue engineering approach for regenerative medicine.Author thanks the Basque Government for granted fellowship to S. Ruiz-Alonso (PRE_2020_2_0143). This study was financially supported by the Basque Country Government (IT907-16), the Ministerio de Economía, Industria y Competitividad (FEDER funds, project RTC-2016- 5451-1), Fundación Mutua Madrileña (project FMM-AP17196-2019), the Instituto de Salud Carlos III, ERDF funds (DTS19/00145) and by the Consejería de Economía, Conocimiento, Empresas y Universidad, Junta de Andalucía (project no. PY18-2470 and SOMM17/6109/UGR, FEDER Funds). Authors also wish to thank the intellectual and technical assistance from the ICTS “NANBIOSIS”, more specifically by the Drug Formulation Unit (U10) of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the University of Basque Country (UPV/ EHU

Applications of fluorescence and bioluminescence resonance energy transfer to drug discovery at G protein coupled receptors

The role of G protein coupled receptors (GPCRs) in numerous physiological processes that may be disrupted or modified in disease makes them key targets for the development of new therapeutic medicines. A wide variety of resonance energy transfer (RET) techniques such as fluorescence RET and bioluminescence RET have been developed in recent years to detect protein–protein interactions in living cells. Furthermore, these techniques are now being exploited to screen for novel compounds that activate or block GPCRs and to search for new, previously undiscovered signaling pathways activated by well-known pharmacologically classified drugs. The high resolution that can be achieved with these RET methods means that they are well suited to study both intramolecular conformational changes in response to ligand binding at the receptor level and intermolecular interactions involving protein translocation in subcellular compartments resulting from external stimuli. In this review we highlight the latest advances in these technologies to illustrate general principles

Ligand regulation of GPCR quaternary structure

G protein-coupled receptors (GPCRs) have been shown not only to be activated by physiologically circulating ligands, but also by a wide variety of other molecules with pharmacological properties which act to selectively stabilize specific sets of receptor conformations that consequently regulate GPCR-modulated signalling cascades in a specific manner. In recent years, the concept of GPCR oligomerization and the ability of these receptors to form larger protein signalling complexes has become an area of intense investigation. Such processes can modulate many steps in the life of a GPCR including intracellular trafficking, folding, internalization and pharmacological properties. Oligomer formation and regulation offers novel opportunities for drug discovery and some ligands have been shown to greatly influence the formation or dissociation of pre-formed oligomers. This chapter provides both an overview of the most recent studies reporting effects of ligands on the formation or stability of GPCR oligomers, and information on the most useful strategies that have been developed to study intermolecular interactions between GPCRs

Chondroitin and Dermatan Sulfate Bioinks for 3D Bioprinting and Cartilage Regeneration

Cartilage is a connective tissue which a limited capacity for healing and repairing. In this context, osteoarthritis (OA) disease may be developed with high prevalence in which the use of scaffolds may be a promising treatment. In addition, three-dimensional (3D) bioprinting has become an emerging additive manufacturing technology because of its rapid prototyping capacity and the possibility of creating complex structures. This study is focused on the development of nanocellulose-alginate (NC-Alg) based bioinks for 3D bioprinting for cartilage regeneration to which it is added chondroitin sulfate (CS) and dermatan sulfate (DS). First, rheological properties are evaluated. Then, sterilization effect, biocompatibility, and printability on developed NC-Alg-CS and NC-Alg-DS inks are evaluated. Subsequently, printed scaffolds are characterized. Finally, NC-Alg-CS and NC-Alg-DS inks are loaded with murine D1-MSCs-EPO and cell viability and functionality, as well as the chondrogenic differentiation ability are assessed. Results show that the addition of both CS and DS to the NC-Alg ink improves its characteristics in terms of rheology and cell viability and functionality. Moreover, differentiation to cartilage is promoted on NC-Alg-CS and NC-Alg-DS scaffolds. Therefore, the utilization of MSCs containing NC-Alg-CS and NC-Alg-DS scaffolds may become a feasible tissue engineering approach for cartilage regeneration.The authors thank the Basque Government for granted fellowship to S.Ruiz-Alonso (PRE_2020_2_0143). This study was financially supported bythe Basque Country Government (IT907-16), the Ministerio de Economía,Industria y Competitividad (FEDER funds, project RTC-2016-5451-1). Theyalso wish to thank the intellectual and technical assistance from the ICTS“NANBIOSIS,” more specifically by the Drug Formulation Unit (U10)of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the University of Basque Country (UPV/EHU). This research wasalso supported by Fundación Mutua Madrileña (project FMM-AP17196-2019), Consejería de Economía, Conocimiento, Empresas y Universi-dad de la Junta de Andalucía (ERDF funds, projects B-CTS-230-UGR18,SOMM17-6109, and P18-FR-2465), and the Instituto de Salud Carlos III,ERDF funds (DTS19/00145 and DTS21/00098). The authors also thank toSpanish Ministry of Science and Innovation (MICINN) (project PID2020-114086RB-100). The corresponding author information was updated onMarch 14, 2022

Modulation of conductivity of alginate hydrogels containing reduced graphene oxide through the addition of proteins

This article belongs to the Special Issue Rational Design and Characterization of Hydrogels to Improve Pharmaceutical and Biomedical Applicability.Modifying hydrogels in order to enhance their conductivity is an exciting field with applications in cardio and neuro-regenerative medicine. Therefore, we have designed hybrid alginate hydrogels containing uncoated and protein-coated reduced graphene oxide (rGO). We specifically studied the adsorption of three different proteins, BSA, elastin, and collagen, and the outcomes when these protein-coated rGO nanocomposites are embedded within the hydrogels. Our results demonstrate that BSA, elastin, and collagen are adsorbed onto the rGO surface, through a non-spontaneous phenomenon that fits Langmuir and pseudo-second-order adsorption models. Protein-coated rGOs are able to preclude further adsorption of erythropoietin, but not insulin. Collagen showed better adsorption capacity than BSA and elastin due to its hydrophobic nature, although requiring more energy. Moreover, collagen-coated rGO hybrid alginate hydrogels showed an enhancement in conductivity, showing that it could be a promising conductive scaffold for regenerative medicine.This study was financially supported by the Basque Country Government [grant number T907-16].Peer reviewe

Cryogel-supported stem cell factory for customized sustained release of bispecific antibodies for cancer immunotherapy

Combining stem cells with biomaterial scaffolds provides a promising strategy for the development of drug delivery systems. Here we propose an innovative immunotherapeutic organoid by housing human mesenchymal stromal cells (MSCs), gene-modified for the secretion of an anti-CD33-anti-CD3 bispecific antibody (bsAb), in a small biocompatible star-shaped poly(ethylene glycol)-heparin cryogel scaffold as a transplantable and low invasive therapeutic machinery for the treatment of acute myeloid leukemia (AML). The macroporous biohybrid cryogel platform displays effectiveness in supporting proliferation and survival of bsAb-releasing-MSCs overtime in vitro and in vivo, avoiding cell loss and ensuring a constant release of sustained and detectable levels of bsAb capable of triggering T-cell-mediated anti-tumor responses and a rapid regression of CD33(+) AML blasts. This therapeutic device results as a promising and safe alternative to the continuous administration of short-lived immunoagents and paves the way for effective bsAb-based therapeutic strategies for future tumor treatments