Current Fertility Preservation Steps in Young Women Suffering from Cancer and Future Perspectives

Childhood cancer incidence, especially in high-income countries, has led to a focus on preserving fertility in this vulnerable population. The common treatments, such as radiation and certain chemotherapeutic agents, though effective, pose a risk to fertility. For adult women, established techniques like embryo and egg freezing are standard, requiring ovarian stimulation. However, for prepubescent girls, ovarian tissue freezing has become the primary option, eliminating the need for hormonal preparation. This review describes the beginning, evolution, and current situation of the fertility preservation options for this young population. A total of 75 studies were included, covering the steps in the current fertility preservation protocols: (i) ovarian tissue extraction, (ii) the freezing method, and (iii) thawing and transplantation. Cryopreservation and the subsequent transplantation of ovarian tissue have resulted in successful fertility restoration, with over 200 recorded live births, including cases involving ovarian tissue cryopreserved from prepubescent girls. Despite promising results, challenges persist, such as follicular loss during transplantation, which is attributed to ischemic and oxidative damage. Optimizing ovarian tissue-freezing processes and exploring alternatives to transplantation, like in vitro systems for follicles to establish maturation, are essential to mitigating associated risks. Further research is required in fertility preservation techniques to enhance clinical outcomes in the future. Ovarian tissue cryopreservation appears to be a method with specific benefits, indications, and risks, which can be an important tool in terms of preserving fertility in younger women.

Human Dermal Decellularized ECM Hydrogels as Scaffolds for 3D In Vitro Skin Aging Models

Biomaterials play an important role in the development of advancing three dimensional (3D) in vitro skin models, providing valuable insights for drug testing and tissue-specific modeling. Commercial materials, such as collagen, fibrin or alginate, have been widely used in skin modeling. However, they do not adequately represent the molecular complexity of skin components. On this regard, the development of novel biomaterials that represent the complexity of tissues is becoming more important in the design of advanced models. In this study, we have obtained aged human decellularized dermal extracellular matrix (dECM) hydrogels extracted from cadaveric human skin and demonstrated their potential as scaffold for advanced skin models. These dECM hydrogels effectively reproduce the complex fibrillar structure of other common scaffolds, exhibiting similar mechanical properties, while preserving the molecular composition of the native dermis. It is worth noting that fibroblasts embedded within human dECM hydrogels exhibit a behavior more representative of natural skin compared to commercial collagen hydrogels, where uncontrolled cell proliferation leads to material shrinkage. The described human dECM hydrogel is able to be used as scaffold for dermal fibroblasts in a skin aging-on-a-chip model. These results demonstrate that dECM hydrogels preserve essential components of the native human dermis making them a suitable option for the development of 3D skin aging models that accurately represent the cellular microenvironment, improving existing in vitro skin models and allowing for more reliable results in dermatopathological studies.

Generation of Self-Induced Myocardial Ischemia in Large-Sized Cardiac Spheroids without Alteration of Environmental Conditions Recreates Fibrotic Remodeling and Tissue Stiffening Revealed by Constriction Assays

A combination of human-induced pluripotent stem cells (hiPSCs) and 3D microtissue culture techniques allows the generation of models that recapitulate the cardiac microenvironment for preclinical research of new treatments. In particular, spheroids represent the simplest approach to culture cells in 3D and generate gradients of cellular access to the media, mimicking the effects of an ischemic event. However, previous models required incubation under low oxygen conditions or deprived nutrient media to recreate ischemia. Here, we describe the generation of large spheroids (i.e., larger than 500 μm diameter) that self-induce an ischemic core. Spheroids were generated by coculture of cardiomyocytes derived from hiPSCs (hiPSC-CMs) and primary human cardiac fibroblast (hCF). In the proper medium, cells formed aggregates that generated an ischemic core 2 days after seeding. Spheroids also showed spontaneous cellular reorganization after 10 days, with hiPSC-CMs located at the center and surrounded by hCFs. This led to an increase in microtissue stiffness, characterized by the implementation of a constriction assay. All in all, these phenomena are hints of the fibrotic tissue remodeling secondary to a cardiac ischemic event, thus demonstrating the suitability of these spheroids for the modeling of human cardiac ischemia and its potential application for new treatments and drug research.

Nanoparticles Stokes radius assessment through permeability coefficient determination within a new stratified epithelium on-chip model

Tissue barrier permeability plays a crucial role in determining the selective transport of substances across epithelial tissues, including drugs, cosmetic substances, and chemicals. The ability of these substances to cross through tissue barriers affects their absorption into the bloodstream and ultimately their effectiveness. Therefore, the determination of their permeability on these type of tissue barriers represents a useful tool for pharmaceutical and cosmetic industries as well as for toxicological studies.In this regard, microfluidic devices and organ-on-chip technologies are becoming more important to generate reliable data. We have designed and performed an alternative new stratified epithelia-on-chip model that allows to correlate the Stokes radius and the diffusion of molecules and/or nanoformulations through the in vitro generated barrier and establish a system suitable for the analysis of diffusion through stratified epithelium. Thus, extrapolating from experimental data we can predict the Stokes radius for unknown fluorescent labelled particles within a molecular size range, such as gold nanoparticles.

Surface modifications of COP-based microfluidic devices for improved immobilisation of hydrogel proteins: long-term 3D culture with contractile cell types and ischaemia model

The tissue microenvironment plays a crucial role in tissue homeostasis and disease progression. However, the in vitro simulation has been limited by the lack of adequate biomimetic models in the last decades. Thanks to the advent of microfluidic technology for cell culture applications, these complex microenvironments can be recreated by combining hydrogels, cells and microfluidic devices. Nevertheless, this advance has several limitations. When cultured in three-dimensional (3D) hydrogels inside microfluidic devices, contractile cells may exert forces that eventually collapse the 3D structure. Disrupting the compartmentalisation creates an obstacle to long-term or highly cell-concentrated assays, which are extremely relevant for multiple applications such as fibrosis or ischaemia. Therefore, we tested surface treatments on cyclic-olefin polymer-based microfluidic devices (COP-MD) to promote the immobilisation of collagen as a 3D matrix protein. Thus, we compared three surface treatments in COP devices for culturing human cardiac fibroblasts (HCF) embedded in collagen hydrogels. We determined the immobilisation efficiency of collagen hydrogel by quantifying the hydrogel transversal area within the devices at the studied time points. Altogether, our results indicated that surface modification with polyacrylic acid photografting (PAA-PG) of COP-MD is the most effective treatment to avoid the quick collapse of collagen hydrogels. As a proof-of-concept experiment, and taking advantage of the low-gas permeability properties of COP-MD, we studied the application of PAA-PG pre-treatment to generate a self-induced ischaemia model. Different necrotic core sizes were developed depending on initial HCF density seeding with no noticeable gel collapse. We conclude that PAA-PG allows long-term culture, gradient generation and necrotic core formation of contractile cell types such as myofibroblasts. This novel approach will pave the way for new relevant in vitro co-culture models where fibroblasts play a key role such as wound healing, tumour microenvironment and ischaemia within microfluidic devices.

Current approaches for the recreation of cardiac ischaemic environment in vitro

Myocardial ischaemia is one of the leading dead causes worldwide. Although animal experiments have historically provided a wealth of information, animal models are time and money consuming, and they usually miss typical human patient's characteristics associated with ischemia prevalence, including aging and comorbidities. Generating reliable in vitro models that recapitulate the human cardiac microenvironment during an ischaemic event can boost the development of new drugs and therapeutic strategies, as well as our understanding of the underlying cellular and molecular events, helping the optimization of therapeutic approaches prior to animal and clinical testing. Although several culture systems have emerged for the recreation of cardiac physiology, mimicking the features of an ischaemic heart tissue in vitro is challenging and certain aspects of the disease process remain poorly addressed. Here, current in vitro cardiac culture systems used for modelling cardiac ischaemia, from self-aggregated organoids to scaffold-based constructs and heart-on-chip platforms are described. The advantages of these models to recreate ischaemic hallmarks such as oxygen gradients, pathological alterations of mechanical strength or fibrotic responses are highlighted. The new models represent a step forward to be considered, but unfortunately, we are far away from recapitulating all complexity of the clinical situations.

Intrapericardial Delivery of APA-Microcapsules as Promising Stem Cell Therapy Carriers in an Experimental Acute Myocardial Infarction Model

The administration of cardiosphere-derived cells (CDCs) after acute myocardial infarction (AMI) is very promising. CDC encapsulation in alginate-poly-l-lysine-alginate (APA) could increase cell survival and adherence. The intrapericardial (IP) approach potentially achieves high concentrations of the therapeutic agent in the infarcted area. We aimed to evaluate IP therapy using a saline vehicle as a control (CON), a dose of 30 × 106 CDCs (CDCs) or APA microcapsules containing 30 × 106 CDCs (APA-CDCs) at 72 h in a porcine AMI model. Magnetic resonance imaging (MRI) was used to determine the left ventricular ejection fraction (LVEF), infarct size (IS), and indexed end diastolic and systolic volumes (EDVi; ESVi) pre- and 10 weeks post-injection. Programmed electrical stimulation (PES) was performed to test arrhythmia inducibility before euthanasia. Histopathological analysis was carried out afterwards. The IP infusion was successful in all animals. At 10 weeks, MRI revealed significantly higher LVEF in the APA-CDC group compared with CON. No significant differences were observed among groups in IS, EDVi, ESVi, PES and histopathological analyses. In conclusion, the IP injection of CDCs (microencapsulated or not) was feasible and safe 72 h post-AMI in the porcine model. Moreover, CDCs APA encapsulation could have a beneficial effect on cardiac function, reflected by a higher LVEF at 10 weeks.

Modulation of Conductivity of Alginate Hydrogels Containing Reduced Graphene Oxide through the Addition of Proteins

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.

Benefits of cryopreservation as long-term storage method of encapsulated cardiosphere-derived cells for cardiac therapy: A biomechanical analysis

Cardiosphere-derived cells (CDCs) encapsulated within alginate-poly-L-lysine-alginate (APA) microcapsules present a promising treatment alternative for myocardial infarction. However, clinical translatability of encapsulated CDCs requires robust long-term preservation of microcapsule and cell stability, since cell culture at 37 °C for long periods prior to patient implantation involve high resource, space and manpower costs, sometimes unaffordable for clinical facilities. Cryopreservation in liquid nitrogen is a well-established procedure to easily store cells with good recovery rate, but its effects on encapsulated cells are understudied. In this work, we assess both the biological response of CDCs and the mechanical stability of microcapsules after long-term (i.e., 60 days) cryopreservation and compare them to encapsulated CDCs cultured at 37 °C. We investigate for the first time the effects of cryopreservation on stiffness and topographical features of microcapsules for cell therapy. Our results show that functionality of encapsulated CDCs is optimum during 7 days at 37 °C, while cryopreservation seems to better guarantee the stability of both CDCs and APA microcapsules properties during longer storage than 15 days. These results point out cryopreservation as a suitable technique for long-term storage of encapsulated cells to be translated from the 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.

Borax-loaded injectable alginate hydrogels promote muscle regeneration in vivo after an injury

Muscle tissue possess an innate regenerative potential that involves an extremely complicated and synchronized process on which resident muscle stem cells play a major role: activate after an injury, differentiate and fuse originating new myofibers for muscle repair. Considerable efforts have been made to design new approaches based on material systems to potentiate muscle repair by engineering muscle extracellular matrix and/or including soluble factors/cells in the media, trying to recapitulate the key biophysical and biochemical cues present in the muscle niche. This work proposes a different and simple approach to potentiate muscle regeneration exploiting the interplay between specific cell membrane receptors. The simultaneous stimulation of borate transporter, NaBC1 (encoded by SLC4A11gene), and fibronectin-binding integrins induced higher number and size of focal adhesions, major cell spreading and actin stress fibers, strengthening myoblast attachment and providing an enhanced response in terms of myotube fusion and maturation. The stimulated NaBC1 generated an adhesion-driven state through a mechanism that involves simultaneous NaBC1/α5β1/αvβ3 co-localization. We engineered and characterized borax-loaded alginate hydrogels for an effective activation of NaBC1 in vivo. After inducing an acute injury with cardiotoxin in mice, active-NaBC1 accelerated the muscle regeneration process. Our results put forward a new biomaterial approach for muscle repair.

Tendon tissue engineering: Cells, growth factors, scaffolds and production techniques

Tendon injuries are a global health problem that affects millions of people annually. The properties of tendons make their natural rehabilitation a very complex and long-lasting process. Thanks to the development of the fields of biomaterials, bioengineering and cell biology, a new discipline has emerged, tissue engineering. Within this discipline, diverse approaches have been proposed. The obtained results turn out to be promising, as increasingly more complex and natural tendon-like structures are obtained. In this review, the nature of the tendon and the conventional treatments that have been applied so far are underlined. Then, a comparison between the different tendon tissue engineering approaches that have been proposed to date is made, focusing on each of the elements necessary to obtain the structures that allow adequate regeneration of the tendon: growth factors, cells, scaffolds and techniques for scaffold development. The analysis of all these aspects allows understanding, in a global way, the effect that each element used in the regeneration of the tendon has and, thus, clarify the possible future approaches by making new combinations of materials, designs, cells and bioactive molecules to achieve a personalized regeneration of a functional tendon.

Force Spectroscopy Imaging and Constriction Assays Reveal the Effects of Graphene Oxide on the Mechanical Properties of Alginate Microcapsules

Microencapsulation of cells in hydrogel-based porous matrices is an approach that has demonstrated great success in regenerative cell therapy. These microcapsules work by concealing the exogenous cells and materials in a robust biomaterial that prevents their recognition by the immune system. A vast number of formulations and additives are continuously being tested to optimize cell viability and mechanical properties of the hydrogel. Determining the effects of new microcapsule additives is a lengthy process that usually requires extensive in vitro and in vivo testing. In this paper, we developed a workflow using nanoindentation (i.e., indentation with a nanoprobe in an atomic force microscope) and a custom-built microfluidic constriction device to characterize the effect of graphene oxide (GO) on three microcapsule formulations. With our workflow, we determined that GO modifies the microcapsule stiffness and surface properties in a formulation-dependent manner. Our results also suggest, for the first time, that GO alters the conformation of the microcapsule hydrogel and its interaction with subsequent coatings. Overall, our workflow can infer the effects of new additives on microcapsule surfaces. Thus, our workflow can contribute to diminishing the time required for the validation of new microcapsule formulations and accelerate their clinical translation.

BSA- and Elastin-Coated GO, but Not Collagen-Coated GO, Enhance the Biological Performance of Alginate Hydrogels

The use of embedded cells within alginate matrices is a developing technique with great clinical applications in cell-based therapies. However, one feature that needs additional investigation is the improvement of alginate-cells viability, which could be achieved by integrating other materials with alginate to improve its surface properties. In recent years, the field of nanotechnology has shown the many properties of a huge number of materials. Graphene oxide (GO), for instance, seems to be a good choice for improving alginate cell viability and functionality. We previously observed that GO, coated with fetal bovine serum (FBS) within alginate hydrogels, improves the viability of embedded myoblasts. In the current research, we aim to study several proteins, specifically bovine serum albumin (BSA), type I collagen and elastin, to discern their impact on the previously observed improvement on embedded myoblasts within alginate hydrogels containing GO coated with FBS. Thus, we describe the mechanisms of the formation of BSA, collagen and elastin protein layers on the GO surface, showing a high adsorption by BSA and elastin, and a decreasing GO impedance and capacitance. Moreover, we described a better cell viability and protein release from embedded cells within hydrogels containing protein-coated GO. We conclude that these hybrid hydrogels could provide a step forward in regenerative medicine.

Graphene oxide and reduced graphene oxide-based scaffolds in regenerative medicine

There is a vast and rapid increase in the applications of graphene oxide (GO) and reduced graphene oxide (rGO) in the biomedical field, including drug delivery, bio-sensing, and diagnostic tools. Among all the applications, the GO and rGO-based scaffolds are a very promising system that have attracted attention because of their great clinical projection in tissue regeneration therapies. Both GO and rGO have shown a strong impact on the proliferation and differentiation of implemented stem cells, but still need to overcome several challenges, such as cytotoxicity, biodistribution, biotransformation or immune response. However, there are still controversial hypothesises regarding the mechanisms involved in these issues that should be clarified in order to improve the applications of these compounds. 3D-scaffolds can help in solving some of those limitations when moving into preclinical studies in regenerative medicine. In this review, we will describe the application of GO and rGO within 3D scaffolds in bone, cardiac and neural regenerative medicine after analyzing the aforementioned challenges.

Immobilization of INS1E Insulin-Producing Cells Within Injectable Alginate Hydrogels

Alginate has demonstrated high applicability as a matrix-forming biomaterial for cell immobilization due to its ability to make hydrogels combined with cells in a rapid and non-toxic manner in physiological conditions, while showing excellent biocompatibility, preserving immobilized cell viability and function. Moreover, depending on its application, alginate hydrogel physicochemical properties such as porosity, stiffness, gelation time, and injectability can be tuned. This technology has been applied to several cell types that are able to produce therapeutic factors. In particular, alginate has been the most commonly used material in pancreatic islet entrapment for type 1 diabetes mellitus treatment. This chapter compiles information regarding the alginate handling, and we describe the most important steps and recommendations to immobilize insulin-producing cells within a tuned injectable alginate hydrogel using a syringe-based mixing system, detailing how to assess the viability and the biological functionality of the embedded cells.

Review of Advanced Hydrogel-Based Cell Encapsulation Systems for Insulin Delivery in Type 1 Diabetes Mellitus

: Type 1 Diabetes Mellitus (T1DM) is characterized by the autoimmune destruction of β-cells in the pancreatic islets. In this regard, islet transplantation aims for the replacement of the damaged β-cells through minimally invasive surgical procedures, thereby being the most suitable strategy to cure T1DM. Unfortunately, this procedure still has limitations for its widespread clinical application, including the need for long-term immunosuppression, the lack of pancreas donors and the loss of a large percentage of islets after transplantation. To overcome the aforementioned issues, islets can be encapsulated within hydrogel-like biomaterials to diminish the loss of islets, to protect the islets resulting in a reduction or elimination of immunosuppression and to enable the use of other insulin-producing cell sources. This review aims to provide an update on the different hydrogel-based encapsulation strategies of insulin-producing cells, highlighting the advantages and drawbacks for a successful clinical application.

Cell Microencapsulation and Cryopreservation with Low Molecular Weight Hyaluronan and Dimethyl Sulfoxide

Cryopreservation is commonly used for the storage of cells, tissues, organs or 3D cell-based products using ultra-low temperatures, which involves the immersion in liquid nitrogen for their long-term preservation. The cryopreservation of several microencapsulated cells is usually performed by the slow freezing with the dimethyl sulfoxide (DMSO) as a cryoprotectant agent (CPA). In this study, we cryopreserved several microencapsulated cells with the natural, non-toxic low molecular-weight hyaluronan (LMW-HA) at 5% and DMSO 10% solution assessing cell viability and metabolic activity after thawing. The cryopreservation of microencapsulated D1 mesenchymal stem cells (D1MSC) and murine myoblast cells (C2C12) with the LMW-HA 5% presented similar outcomes after thawing compared to the DMSO solution, showing the low molecular weight hyaluronan as a natural, non-toxic CPA that can be used preventing the DMSO related adverse effects after the implantation of the cryopreserved cell-based products.

Type 1 Diabetes Mellitus reversal via implantation of magnetically purified microencapsulated pseudoislets

Microencapsulation of pancreatic islets for the treatment of Type I Diabetes Mellitus (T1DM) generates a high quantity of empty microcapsules, resulting in high therapeutic graft volumes that can enhance the host's immune response. We report a 3D printed microfluidic magnetic sorting device for microcapsules purification with the objective to reduce the number of empty microcapsules prior transplantation. In this study, INS1E pseudoislets were microencapsulated within alginate (A) and alginate-poly-L-lysine-alginate (APA) microcapsules and purified through the microfluidic device. APA microcapsules demonstrated higher mechanical integrity and stability than A microcapsules, showing better pseudoislets viability and biological function. Importantly, we obtained a reduction of the graft volume of 77.5% for A microcapsules and 78.6% for APA microcapsules. After subcutaneous implantation of induced diabetic Wistar rats with magnetically purified APA microencapsulated pseudoislets, blood glucose levels were restored into normoglycemia (<200 mg/dL) for almost 17 weeks. In conclusion, our described microfluidic magnetic sorting device represents a great alternative approach for the graft volume reduction of microencapsulated pseudoislets and its application in T1DM disease.

Graphene oxide enhances alginate encapsulated cells viability and functionality while not affecting the foreign body response

The combination of protein-coated graphene oxide (GO) and microencapsulation technology has moved a step forward in the challenge of improving long-term alginate encapsulated cell survival and sustainable therapeutic protein release, bringing closer its translation from bench to the clinic. Although this new approach in cell microencapsulation represents a great promise for long-term drug delivery, previous studies have been performed only with encapsulated murine C2C12 myoblasts genetically engineered to secrete murine erythropoietin (C2C12-EPO) within 160 µm diameter hybrid alginate protein-coated GO microcapsules implanted into syngeneic mice. Here, we show that encapsulated C2C12-EPO myoblasts survive longer and release more therapeutic protein by doubling the micron diameter of hybrid alginate-protein-coated GO microcapsules to 380 µm range. Encapsulated mesenchymal stem cells (MSC) genetically modified to secrete erythropoietin (D1-MSCs-EPO) within 380 µm-diameter hybrid alginate-protein-coated GO microcapsules confirmed this improvement in survival and sustained protein release in vitro. This improved behavior is reflected in the hematocrit increase of allogeneic mice implanted with both encapsulated cell types within 380 µm diameter hybrid alginate-protein-coated GO microcapsules, showing lower immune response with encapsulated MSCs. These results provide a new relevant step for the future clinical application of protein-coated GO on cell microencapsulation.

Low molecular-weight hyaluronan as a cryoprotectant for the storage of microencapsulated cells

The low-temperature storage of therapeutic cell-based products plays a crucial role in their clinical translation for the treatment of diverse diseases. Although dimethylsulfoxide (DMSO) is the most successful cryoprotectant in slow freezing of microencapsulated cells, it has shown adverse effects after cryopreserved cell-based products implantation. Therefore, the search of alternative non-toxic cryoprotectants for encapsulated cells is continuously investigated to move from bench to the clinic. In this work, we investigated the low molecular-weight hyaluronan (low MW-HA), a natural non-toxic and non-sulfated glycosaminoglycan, as an alternative non-permeant cryoprotectant for the slow freezing cryopreservation of encapsulated cells. Cryopreservation with low MW-HA provided similar metabolic activity, cell dead and early apoptotic cell percentage and membrane integrity after thawing, than encapsulated cells stored with either DMSO 10% or Cryostor 10. However, the beneficial outcomes with low MW-HA were not comparable to DMSO with some encapsulated cell types, such as the human insulin secreting cell line, 1.1B4, maybe explained by the different expression of the CD44 surface receptor. Altogether, we can conclude that low MW-HA represents a non-toxic natural alternative cryoprotectant to DMSO for the cryopreservation of encapsulated cells.

3D Printed porous polyamide macrocapsule combined with alginate microcapsules for safer cell-based therapies

Cell microencapsulation is an attractive strategy for cell-based therapies that allows the implantation of genetically engineered cells and the continuous delivery of de novo produced therapeutic products. However, the establishment of a way to retrieve the implanted encapsulated cells in case the treatment needs to be halted or when cells need to be renewed is still a big challenge. The combination of micro and macroencapsulation approaches could provide the requirements to achieve a proper immunoisolation, while maintaining the cells localized into the body. We present the development and characterization of a porous implantable macrocapsule device for the loading of microencapsulated cells. The device was fabricated in polyamide by selective laser sintering (SLS), with controlled porosity defined by the design and the sintering conditions. Two types of microencapsulated cells were tested in order to evaluate the suitability of this device; erythropoietin (EPO) producing C2C12 myoblasts and Vascular Endothelial Growth Factor (VEGF) producing BHK fibroblasts. Results showed that, even if the metabolic activity of these cells decreased over time, the levels of therapeutic protein that were produced and, importantly, released to the media were stable.

Microencapsulated macrophages releases conditioned medium able to prevent epithelial to mesenchymal transition

Epithelial to mesenchymal transition (EMT) has emerged as a key process in the development of renal fibrosis. In fact, EMT-derived fibroblasts contribute to the progression of chronic renal disease. In addition, anti-inflammatory M2 macrophages have exhibited a great influence on renal fibrosis. However, because of the high impact that the inputs of different environmental cytokines have on their phenotype, macrophages can easily lose this property. We aim to known if microencapsulated macrophages on M2-inducing alginate matrices could preserve macrophage phenotype and thus release factors able to act on epithelial cells to prevent the epithelial differentiation towards mesenchymal cells. We reproduced an in vitro model of EMT by treating adipose-derived stem cells with all-trans retinoic acid (ATRA) and induced their transformation toward epithelia. Dedifferentiation of epithelial cells into a mesenchymal phenotype occurred when ATRA was retired, thus simulating EMT. Results indicate that induction of M2 phenotype by IL-10 addition in the alginate matrix produces anti-inflammatory cytokines and increases the metabolic activity and the viability of the encapsulated macrophages. The released conditioned medium modulates EMT and maintains healthy epithelial phenotype. This could be used for in vivo cell transplantation, or alternatively as an external releaser able to prevent epithelial to mesenchymal transformation for future anti-fibrotic therapies.

Cryopreservation of Human Mesenchymal Stem Cells in an Allogeneic Bioscaffold based on Platelet Rich Plasma and Synovial Fluid

Transplantation of mesenchymal stem cells (MSCs) has emerged as an alternative strategy to treat knee osteoarthritis. In this context, MSCs derived from synovial fluid could provide higher chondrogenic and cartilage regeneration, presenting synovial fluid as an appropriate MSCs source. An allogeneic and biomimetic bioscaffold composed of Platelet Rich Plasma and synovial fluid that preserve and mimics the natural environment of MSCs isolated from knee has also been developed. We have optimized the cryopreservation of knee-isolated MSCs embedded within the aforementioned biomimetic scaffold, in order to create a reserve of young autologous embedded knee MSCs for future clinical applications. We have tested several cryoprotectant solutions combining dimethyl sulfoxide (DMSO), sucrose and human serum and quantifying the viability and functionality of the embedded MSCs after thawing. MSCs embedded in bioscaffolds cryopreserved with DMSO 10% or the combination of DMSO 10% and Sucrose 0,2 M displayed the best cell viabilities maintaining the multilineage differentiation potential of MSCs after thawing. In conclusion, embedded young MSCs within allogeneic biomimetic bioscaffold can be cryopreserved with the cryoprotectant solutions described in this work, allowing their future clinical use in patients with cartilage defects.

Alginate Microcapsules Incorporating Hyaluronic Acid Recreate Closer in Vivo Environment for Mesenchymal Stem Cells

The potential clinical application of alginate cell microencapsulation has advanced enormously during the past decade. However, the 3D environment created by alginate beads does not mimic the natural extracellular matrix surrounding cells in vivo, responsible of cell survival and functionality. As one of the most frequent macromolecules present in the extracellular matrix is hyaluronic acid, we have formed hybrid beads with alginate and hyaluronic acid recreating a closer in vivo cell environment. Our results show that 1% alginate-0.25% hyaluronic acid microcapsules retain 1.5% alginate physicochemical properties. Moreover, mesenchymal stem cells encapsulated in these hybrid beads show enhanced viability therapeutic protein release and mesenchymal stem cells' potential to differentiate into chondrogenic lineage. Although future studies with additional proteins need to be done in order to approach even more the extracellular matrix features, we have shown that hyaluronic acid protects alginate encapsulated mesenchymal stem cells by providing a niche-like environment and remaining them competent as a sustainable drug delivery system.

Microencapsulated Cells for Cancer Therapy

The microencapsulation of different types of cells that are able to produce therapeutic factors is being investigated for the treatment of several human diseases. Most efforts are focused on chronic and degenerative diseases as this strategy could become an alternative to some commonly used parenteral treatments that need to be repeatedly administered. But, this approach has also been investigated in the field of oncology with the aim of providing immunomodulatory antibodies that are able to enhance the patient's inherent immune response against the tumor. These kind of treatments would provide the patient with the therapeutic drug produced in situ, de novo, and in a sustained way, making the therapy more comfortable.Although different devices are nowadays available to produce cell-enclosing alginate-microcapsules, here, we describe the most important steps and advices in order to fabricate alginate-poly-L-lysine-alginate microcapsules containing hybridoma cells for cancer management using an electrostatic bead generator, and how to evaluate the viability of those cells over the time.

Use of Flow Focusing Technique for Microencapsulation of Myoblasts

Alginate cell microencapsulation implies the immobilization of cells within a polymeric membrane that allows the bidirectional diffusion of nutrients and oxygen inside the microcapsules and the release of waste and therapeutic molecules outside them. This technology has been applied to several cell types and it has been extensively described with pancreatic islets. However, other cells such as myoblasts are being currently studied and showing high interest. Moreover, different systems and approaches have been developed for cell encapsulation such as electrostatic extrusion and Flow focusing technology. When Flow focusing technology is applied for myoblast encapsulation, several factors should be considered, such as the pressure, the flow of the system, or the diameter size of the nebulizer, which will determine the final diameter size and shape of the microcapsules containing the myoblasts. Finally, viability of encapsulated myoblasts needs to be assessed before further studies are performed.

Assessment of the Behavior of Mesenchymal Stem Cells Immobilized in Biomimetic Alginate Microcapsules

The combination of mesenchymal stem cells (MSCs) and biomimetic matrices for cell-based therapies has led to enormous advances, including the field of cell microencapsulation technology. In the present work, we have evaluated the potential of genetically modified MSCs from mice bone marrow, D1-MSCs, immobilized in alginate microcapsules with different RGD (Arg-Gly-Asp) densities. Results demonstrated that the microcapsules represent a suitable platform for D1-MSC encapsulation since cell immobilization into alginate matrices does not affect their main characteristics. The in vitro study showed a higher activity of D1-MSCs when they are immobilized in RGD-modified alginate microcapsules, obtaining the highest therapeutic factor secretion with low and intermediate densities of the bioactive molecule. In addition, the inclusion of RGD increased the differentiation potential of immobilized cells upon specific induction. However, subcutaneous implantation did not induce differentiation of D1-MSCs toward any lineage remaining at an undifferentiated state in vivo.

Advances in cell encapsulation technology and its application in drug delivery

INTRODUCTION

Cell encapsulation technology has improved enormously since it was proposed 50 years ago. The advantages offered over other alternative systems, such as the prevention of repetitive drug administration, have triggered the use of this technology in multiple therapeutic applications.

AREAS COVERED

In this article, improvements in cell encapsulation technology and strategies to overcome the drawbacks that prevent its use in the clinic have been summarized and discussed. Different studies and clinical trials that have been performed in several therapeutic applications have also been described.

EXPERT OPINION

The authors believe that the future translation of this technology from bench to bedside requires the optimization of diverse aspects: i) biosafety, controlling and monitoring cell viability; ii) biocompatibility, reducing pericapsular fibrotic growth and hypoxia suffered by the graft; iii) control over drug delivery; iv) and the final scale up. On the other hand, an area that deserves more attention is the cryopreservation of encapsulated cells as this will facilitate the arrival of these biosystems to the clinic.

The migration of hematopoietic progenitors from the fetal liver to the fetal bone marrow: lessons learned and possible clinical applications

The ontogeny of hematopoietic stem cells (HSCs) is complex, with multiple sites of embryonic origin as well as several locations of expansion and maturation in the embryo and the adult. Hematopoietic progenitors (HPs) with diverse developmental potential are first found in the yolk sac, aorta-gonad-mesonephros region and placenta. These progenitors then colonize the fetal liver (FL), where they undergo expansion and maturation. HSCs from the FL colonize the fetal bone marrow (FBM), governed by a complex orchestration of transcription programs including migratory molecules with chemotactic activity, adhesion molecules, and molecules that modulate the extracellular matrix. Understanding the mechanisms that regulate the patterns of HSC migration between FL and FBM could improve the engraftment potential of embryonic stem cell-derived HPs, because these cells might display a migratory behavior more similar to early HPs than to adult HSCs. Understanding the changes in migratory behavior in the context of FL to FBM HSC migration could lead to new approaches in the treatment of blood malignancies. We will review the current knowledge in the field of FL to the FBM HSCs migration during development, focusing on changes in expression of molecules important for this process and exploring its clinical applications.

Non-viral gene delivery of the GDNF, either alone or fused to the C-fragment of tetanus toxin protein, prolongs survival in a mouse ALS model

PURPOSE AND BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease with no effective therapy. Glial-cell line derived neurotrophic factor (GDNF) has been translated to clinical trials for treatment of ALS and its selective delivery to the motoneurons could improve its therapeutic abilities.

METHODS

To test this idea, we genetically fused GDNF to the C-fragment of tetanus toxin (TTC), a peptide able to specifically deliver molecules to motoneurons.

RESULTS

Single intramuscular administration of naked-DNA encoding GDNF or GDNF-TTC significantly delayed the onset of symptoms and functional deficits into the SODG93A mouse model of ALS, prolonging their lifespan.

CONCLUSIONS

We have demonstrated a neuroprotective effect of GDNF-TTC as shown by the activation of survival pathways and inhibition of apoptotic proteins, such as Akt phosphorylation, or reduced caspase-3 activation respectively. However, the GDNF fusion with TTC did not improve the therapeutic effects when compared to GDNF alone.

Single-cell analysis of murine long-term hematopoietic stem cells reveals distinct patterns of gene expression during fetal migration

BACKGROUND

Long-term hematopoietic stem cells (LT-HSCs) migrate from the fetal liver (FL) to the fetal bone marrow (FBM) during development. Various adhesion and chemotactic receptor genes have been implicated in the migration of adult LT-HSCs. However, their role in the migration of fetal LT-HSCs is not clearly understood due, in part, to the rare number of these cells in fetal tissues, which preclude classical gene expression analysis. The aim of this study is to characterize the expression of migration related genes in fetal LT-HSC across different anatomical locations during development.

METHODOLOGY/PRINCIPAL FINDINGS

We isolated fetal LT-HSC from different developmental stages, as well as different anatomical locations, and performed single-cell multiplex RT-qPCR and flow cytometry analysis of eight molecules involved in adult LT-HSC migration. Our results show that the gene expression of the chemokine receptor Cxcr4 in LT-HSC varies across developmental microenvironments and times, while the cadherin Cdh2 (Ncad) and the calcium receptor Casr show higher gene expression and variability only in FBM at 17.5 days post coitum (dpc). The cadherin Cdh5 (Vecad) maintains high expression variability only during fetal development, while the integrin subunit Itga5 (α5) increases its variability after 14.5 dpc. The integrin subunits Itga4 (α4) and Itgal (Lfa1), as well as the selectin ligand Selplg (Psgl1), did not show differences in their expression in single LT-HSCs irrespective of the developmental times or anatomical microenvironments studied.

CONCLUSIONS/SIGNIFICANCE

Our data demonstrate that the expression pattern of phenotypically identical, single LT-HSCs fluctuates as a function of developmental stage and anatomical microenvironment. This is the first exhaustive gene expression comparison of migration-related molecules in fetal tissues across developmental times, enhancing the understanding of LT-HSC migration fate decisions during development.

Robo4 cooperates with CXCR4 to specify hematopoietic stem cell localization to bone marrow niches

Specific bone marrow (BM) niches are critical for hematopoietic stem cell (HSC) function during both normal hematopoiesis and in stem cell transplantation therapy. We demonstrate that the guidance molecule Robo4 functions to specifically anchor HSCs to BM niches. Robo4-deficient HSCs displayed poor localization to BM niches and drastically reduced long-term reconstitution capability while retaining multilineage potential. Cxcr4, a critical regulator of HSC location, is upregulated in Robo4(-/-) HSCs to compensate for Robo4 loss. Robo4 deletion led to altered HSC mobilization efficiency, revealing that inhibition of both Cxcr4- and Robo4-mediated niche interactions are necessary for efficient HSC mobilization. Surprisingly, we found that WT HSCs express very low levels of Cxcr4 and respond poorly to Cxcr4 manipulation relative to other hematopoietic cells. We conclude that Robo4 cooperates with Cxcr4 to endow HSCs with competitive access to limited stem cell niches, and we propose Robo4 as a therapeutic target in HSC transplantation therapy.

Expression of migration-related genes is progressively upregulated in murine Lineage-Sca-1+c-Kit+ population from the fetal to adult stages of development

Introduction

Hematopoietic stem cells (HSCs) follow a genetically programmed pattern of migration during development. Extracellular matrix and adhesion molecules, as well as chemokines and their receptors, are important in adult HSC migration. However, little is known about the role these molecules play at earlier developmental stages.

Methods

We have analyzed by quantitative polymerase chain reaction (qPCR) array the expression pattern of extracellular matrix and adhesion molecules as well as chemokines and chemokine receptors in Lineage^-Sca-1⁺c-Kit⁺ (LSK) cells at different stages of development, in order to characterize the role played by these molecules in LSK. Data were represented by volcano plots to show the differences in expression pattern at the time points studied.

Results

Our results show marked changes in the expression pattern of extracellular matrix, adhesion molecules, chemokines and their receptors with developmental age, particularly in later stages of development. Ten molecules were significantly increased among the LSK populations studied. Our screen identified the upregulation of Col4a1, as well as molecules involved in its degradation (Mmp2, Timp2), with development. Other genes identified were Sell, Tgfbi, and Entpd1. Furthermore, we show that the expression of the chemokines Ccl4, Ccl9, Il18 and the chemokine receptor Cxcr4 increases in LSK cells during development.

Conclusions

Several genes are upregulated in the LSK population in their transition to the bone marrow microenvironment, increasing at later stages of development. This gene pattern should be emulated by embryonic stem cell-derived hematopoietic progenitors in order to improve their properties for clinical applications such as engraftment.

Use of B7 costimulatory molecules as adjuvants in a prime-boost vaccination against Visna/Maedi ovine lentivirus

RNA transcripts of the B7 family molecule (CD80) are diminished in blood leukocytes from animals clinically affected with Visna/Maedi virus (VMV) infection. This work investigates whether the use of B7 genes enhances immune responses and protection in immunization-challenge approaches. Sheep were primed by particle-mediated epidermal bombardment with VMV gag and env gene recombinant plasmids together with plasmids encoding both CD80 and CD86 or CD80 alone, boosted with gag and env gene recombinant modified vaccinia Ankara virus and challenged intratracheally with VMV. Immunization in the presence of one or both of the B7 genes resulted in CD4+ T cell activation and antibody production (before and after challenge, respectively), but only immunization with CD80 and CD86 genes together, and not CD80 alone, resulted in a reduced number of infected animals and increased early transient cytotoxic T lymphocytes (CTL) responses. Post-mortem analysis showed an immune activation of lymphoid tissue in challenge-target organs in those animals that had received B7 genes compared to unvaccinated animals. Thus, the inclusion of B7 genes helped to enhance early cellular responses and protection (diminished proportion of infected animals) against VMV infection.

Optimal methods to characterize the G93A mouse model of ALS

In the present study, we used the SOD1 (G93A) mutant transgenic mice as a model of amyotrophic lateral sclerosis (ALS). This model is widely used as a laboratory tool to study experimental treatments in vivo for ALS to investigate new therapeutic strategies for this neurodegenerative disease. Such studies require the objective quantification of different parameters while mice develop the disease. We have applied a battery of different and specific tests: scoring of motor deficits by a trained observer, weighing, survival measure, hanging wire test, rotarod task and electromyography, most of them commonly used to evaluate G93A animals. We have critically compared these methods, showing the significant influence of gender on the onset of symptoms, and the optimal moment to apply each test. These results should be taken into account in future therapeutic assays on this ALS model.

A genetic fusion GDNF-C fragment of tetanus toxin prolongs survival in a symptomatic mouse ALS model

PURPOSE

Amyotrophic Lateral Sclerosis (ALS) is a paralyzing disorder that kills individuals within three to five years of onset without any possibility for effective treatment. One proposed therapy has been the use of neurotrophic factors to inhibit the apoptosis of motorneurones. At the present, one way to deliver neurotrophic factors after intramuscular injection to the motor neurones is through the use of adenoviral vectors. An alternative strategy is the use of the atoxic C fragment of tetanus toxin (TTC) as a neurotrophic factor carrier for motorneurones.

METHODS

We have produced the recombinant protein fusion Glial Derived Neurotrophic Factor and C fragment of tetanus toxin (GDNF-TTC) and we have tested its antiapoptotic activity in degeneration culture cells and in the symptomatic SOD;{G93A} transgenic animal model for ALS.

RESULTS

We demonstrated that GDNF-TTC induces the neuronal survival Akt kinase pathway in mouse cortical culture neurons and~maintains its antiapoptotic neuronal activity in Neuro2A cells. Moreover, we have found that genetic fusion is able to increase survival by 9 days and improves life quality in symptomatic ALS animal models.

CONCLUSION

These results suggest that recombinant GDNF-TTC fusion protein intramuscular injections provide a potential therapy for ALS treatment.

A non-viral vector for targeting gene therapy to motoneurons in the CNS

Gene therapy vectors that can be targeted to motoneuronal cells are required in the field of neurodegenerative diseases. We propose the use of the atoxic fragment C of tetanus toxin (TTC) as biological activity carrier to the motoneurons. Naked DNA encoding beta-galactosidase-TTC hybrid protein was used to transfect muscle cells in vivo, resulting in a selective gene transfer of the enzymatic activity to the CNS. In the muscle, level expression of beta-galactosidase was readily detectable 24 h after injection, reaching a maximum after 4 days and gradually decreasing thereafter. Labelling in the hypoglossal motoneurons and motor cortex was observed from 4 days after injection. In this paper, we show that TTC works as an enzymatic activity carrier to the CNS when muscle cells are transfected in vivo. We have also shown that the presence of TTC does not have any influence on the expression of the transfected gene. Both these results warrant further studies of TTC as a means of treating motoneuron diseases in the field of gene therapy.