Hyaluronic Acid Promotes Differentiation of Mesenchymal Stem Cells from Different Sources toward Pancreatic Progenitors within Three-Dimensional Alginate Matrixes.

Islet transplantation has shown to be a successful alternative in type 1 diabetes treatment, but donor scarcity precludes its worldwide clinical translation. Stem cells are an unlimited source that could circumvent the lack of donors if complete differentiation into insulin-producing cells (IPCs) could be accomplished. We have performed the differentiation of mesenchymal stem cells (MSCs) from different sources into IPCs within three-dimensional (3D) alginate matrixes. We quantified an increased insulin release at the final stage of differentiation compared to undifferentiated MSCs, which is more pronounced in IPCs differentiated from pancreatic-derived MSCs tissues. Moreover, the addition of hyaluronic acid (HA) in alginate microcapsules enhanced, even more, the insulin release from the final IPCs, independent of the MSC source. We can conclude that MSCs can be differentiated into IPCs within alginate microcapsules, enhancing insulin release when HA is present in the 3D alginate matrixes.

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.

Generation of the human iPSC line ESi082-A from a patient with macular dystrophy associated to mutations in the CRB1 gene.

Retinal dystrophies associated to mutations in the CRB1 gene comprise a wide array of clinical presentations. A blood sample from a patient with a family history of CRB1-retinal dystrophy was used to prepare the iPSC line ESi082-A. The genotype of the donor, affected of a perifoveal-bilateral macular dystrophy includes one frameshift deletion and one hypomorphic allele. ESi082-A cell line has been characterized for pluripotency and will be used to prepare retinal cellular models to study the dysfunction leading to the disease.

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.

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.

Hyaluronic acid enhances cell survival of encapsulated insulin-producing cells in alginate-based microcapsules.

Pancreatic islet transplantation has proved to be a promising therapy for T1DM, in spite of the chronic immunosuppression required. Although cell microencapsulation technology represents an alternative to circumvent the immune system rejection of transplanted pancreatic islets, the environment provided by classical alginate microcapsules does not mimic the natural ECM, affecting the islet survival. Since hyaluronic acid, one of the major components of pancreatic ECM, is involved in cell adhesion and viability, we assessed the beneficial outcomes on encapsulated insulin-producing cells by the HA inclusion in alginate matrices. In this manuscript we describe how alginate-HA hybrid microcapsules enhance the viability of encapsulated cells, reducing early apoptosis percentage and decreasing membrane damage. A stable insulin production was maintained in encapsulated cells, not altering the response to a glucose stimulus. Therefore, we can conclude that the inclusion of HA within alginate microcapsules is beneficial for encapsulated insulin-producing cells, representing a step forward in the clinical translation of microcapsules technology for the treatment of T1DM.

3D printed polyamide macroencapsulation devices combined with alginate hydrogels for insulin-producing cell-based therapies.

Cell macroencapsulation has shown a great potential overcoming the low survival of the transplanted pancreatic islets in the Type 1 Diabetes Mellitus (T1DM) treatment, as it avoids the need for lifelong immunosuppression. It is still not completely known how these devices interact with the host immune system when implanted. However, their surface properties seem to be crucial factors for a successful implant. In this context, the hydrophilicity and porosity of the surface of the macrocapsules are two of the most important properties that can affect the functionality of the graft; hydrophilicity defines the interactions with the host's immune cells, while the porosity determines the biosafety of the device while conditioning the oxygen, nutrients and insulin diffusion. Here, we report a novel ß-cell macroencapsulation system that combines an injectable alginate hydrogel with an external 3D-printed implantable device. This external macrocapsule protects the inner hydrogel containing cells, while allowing the precise location of the implant in the body. In addition, it would allow the easy extraction of the grafted cells in the case the implant fails or the renewal of the therapeutic cells is required. This study evaluates the biological effect of the macroencapsulation devices' surface properties (hydrophilicity and porosity). We studied two different pore sizes and hydrophilicities in four different devices containing rat INS1E ß-cells embedded in alginate hydrogels. All the devices showed great biocompatibility, although the hydrophilic ones exhibited higher fibroblast adhesion, which could potentially enhance the fibrotic response when implanted. Importantly, INS1E cells did not escape from the devices, denoting high biosafety. Cells grown within all devices and maintained their insulin secretory function. However, the hydrophobic device with a smaller pore size showed better cell viability values and, therefore, it might be the best candidate for the development of a safe ß-cell replacement therapy in T1DM.

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 ß-cells in the pancreatic islets. In this regard, islet transplantation aims for the replacement of the damaged ß-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.

Current advanced therapy cell-based medicinal products for type-1-diabetes treatment.

In the XXI century diabetes mellitus has become one of the main threats to human health with higher incidence in regions such as Europe and North America. Type 1 diabetes mellitus (T1DM) occurs as a consequence of the immune-mediated destruction of insulin producing ß-cells located in the endocrine part of the pancreas, the islets of Langerhans. The administration of exogenous insulin through daily injections is the most prominent treatment for T1DM but its administration is frequently associated to failure in glucose metabolism control, finally leading to hyperglycemia episodes. Other approaches have been developed in the past decades, such as whole pancreas and islet allotransplantation, but they are restricted to patients who exhibit frequent episodes of hypoglycemia or renal failure because the lack of donors and islet survival. Moreover, patients transplanted with either whole pancreas or islets require of immune suppression to avoid the rejection of the transplant. Currently, advanced therapy medicinal products (ATMP), such as implantable devices, have been developed in order to reduce immune rejection response while increasing cell survival. To overcome these issues, ATMPs must promote vascularization, guaranteeing the nutritional contribution, while providing O2 until vasculature can surround the device. Moreover, it should help in the immune-protection to avoid acute and chronic rejection. The transplanted cells or islets should be embedded within biomaterials with tunable properties like injectability, stiffness and porosity mimicking natural ECM structural characteristics. And finally, an infinitive cell source that solves the donor scarcity should be found such as insulin producing cells derived from mesenchymal stem cells (MSCs), embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Several companies have registered their ATMPs and future studies envision new prototypes. In this review, we will discuss the mechanisms and etiology of diabetes, comparing the clinical trials in the last decades in order to define the main characteristics for future ATMPs.

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.