RESUMEN
Islet transplantation is emerging as a therapeutic option for type 1 diabetes, albeit, only a small number of patients meeting very stringent criteria are eligible for the treatment because of the side effects of the necessary immunosuppressive therapy and the relatively short time frame of normoglycemia that most patients achieve. The challenge of the immune-suppressive regimen can be overcome through microencapsulation of the islets in a perm-selective coating of alginate microbeads with poly-l-lysine or poly- l-ornithine. In addition to other issues including the nutrient supply challenge of encapsulated islets a critical requirement for these cells has emerged as the need to engineer the microenvironment of the encapsulation matrix to mimic that of the native pancreatic scaffold that houses islet cells. That microenvironment includes biological and mechanical cues that support the viability and function of the cells. In this study, the alginate hydrogel was modified to mimic the pancreatic microenvironment by incorporation of extracellular matrix (ECM). Mechanical and biological changes in the encapsulating alginate matrix were made through stiffness modulation and incorporation of decellularized ECM, respectively. Islets were then encapsulated in this new biomimetic hydrogel and their insulin production was measured after 7 days in vitro. We found that manipulation of the alginate hydrogel matrix to simulate both physical and biological cues for the encapsulated islets enhances the mechanical strength of the encapsulated islet constructs as well as their function. Our data suggest that these modifications have the potential to improve the success rate of encapsulated islet transplantation.
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Alginatos/química , Materiales Biomiméticos/química , Células Inmovilizadas/metabolismo , Microambiente Celular , Células Secretoras de Insulina/metabolismo , Andamios del Tejido/química , Supervivencia Celular , Células Inmovilizadas/citología , Matriz Extracelular Descelularizada/química , Humanos , Insulina/biosíntesis , Células Secretoras de Insulina/citologíaRESUMEN
BACKGROUND: The Slit-Robo pathway is a key regulator of angiogenesis and cellular function in experimental models. Slit3 proteins exhibit both proangiogenic and antiangiogenic properties, but the exact mechanism remains unclear. It is theorized that Slit3 may be a potential treatment for vascular diseases and cancer. METHODS: Slit3 labeled with I-125 was encapsulated in microbeads composed of low-viscosity alginate of high-glucuronic acid content, first coated with poly-L-ornithine for various durations and finally with low-viscosity high mannuronic acid. Gamma counter was used to measure microbead encapsulation efficiency and Slit3 release. Markers of angiogenesis were assessed with Boyden chamber, scratch wound, and Matrigel tube formation assays using human umbilical vein and mouse endothelial cells. RESULTS: On incubation of Slit3-loaded microbeads, there was an initial burst phase release of Slit3 for the first 24 h followed by sustained release for 6 to 12 d. Microbead composition determined encapsulation efficiency and rate of release; Slit3 encapsulation was most efficient in microbeads with lower low-viscosity alginate of high-glucuronic acid content concentrations (1.5%) and no poly-L-ornithine coating. Compared with controls (media alone), Slit3 microbeads significantly inhibited in vitro cellular migration, endothelial cell migration for wound closure at 24 and 48 h and endothelial tube formation (P < 0.001, respectively). CONCLUSIONS: Slit3 can be effectively encapsulated and delivered via a controlled release pattern using alginate microbeads. Microbead encapsulation reduces in vitro endothelial tube formation and inhibits cellular migration to impair angiogenesis. Thus, Slit3 microparticles may be explored as a therapeutic option to mitigate tumor proliferation.
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Alginatos/química , Portadores de Fármacos/química , Células Endoteliales de la Vena Umbilical Humana/efectos de los fármacos , Proteínas de la Membrana/administración & dosificación , Neovascularización Patológica/tratamiento farmacológico , Animales , Línea Celular , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Composición de Medicamentos/métodos , Liberación de Fármacos , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Proteínas de la Membrana/farmacocinética , Ratones , Microesferas , Neoplasias/irrigación sanguínea , Neoplasias/tratamiento farmacológico , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/farmacocinéticaRESUMEN
BACKGROUND: It has been suggested that the ectopic expression of PDX1, a dominant pancreatic transcription factor, plays a critical role in the developmental programming of the pancreas even from cells of unrelated tissues such as keratinocytes and amniotic fluid stem cells. In this study we have chosen to drive pancreatic development in human amnion epithelial cells by inducing endogenous PDX1 expression. Further, we have investigated the role of Epidermal Growth Factor (EGF) and Poly-L-Ornithine (PLO) on this differentiation process. RESULTS: Human amnion epithelial cells expressed high levels of endogenous PDX1 upon transduction with an adenoviral vector expressing murine Pdx1. Other markers of various stages of pancreatic differentiation such as NKX6.1, SOX17, RFX6, FOXA2, CFTR, NEUROD1, PAX4 and PPY were also expressed upon Pdx1 transduction. Although initial expression of pancreatic progenitor markers was higher in culture conditions lacking EGF, for a sustained and increased expression EGF was required. Culture on PLO further increased the positive impact of EGF. CONCLUSION: Pancreatic marker expression subsequent to mPdx1 transduction suggests that this approach may facilitate the in vitro differentiation of hAECs into cells of the endocrine pancreas. This result may have important implications in diabetes therapy.
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Amnios/citología , Diferenciación Celular/efectos de los fármacos , Factor de Crecimiento Epidérmico/farmacología , Células Epiteliales/citología , Proteínas de Homeodominio/metabolismo , Péptidos/farmacología , Transactivadores/metabolismo , Animales , Biomarcadores/metabolismo , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Humanos , Ratones , Transducción GenéticaRESUMEN
OBJECTIVES: Our study aims at producing acellular extracellular matrix scaffolds from the human pancreas (hpaECMs) as a first critical step toward the production of a new-generation, fully human-derived bioartificial endocrine pancreas. In this bioartificial endocrine pancreas, the hardware will be represented by hpaECMs, whereas the software will consist in the cellular compartment generated from patient's own cells. BACKGROUND: Extracellular matrix (ECM)-based scaffolds obtained through the decellularization of native organs have become the favored platform in the field of complex organ bioengineering. However, the paradigm is now switching from the porcine to the human model. METHODS: To achieve our goal, human pancreata were decellularized with Triton-based solution and thoroughly characterized. Primary endpoints were complete cell and DNA clearance, preservation of ECM components, growth factors and stiffness, ability to induce angiogenesis, conservation of the framework of the innate vasculature, and immunogenicity. Secondary endpoint was hpaECMs' ability to sustain growth and function of human islet and human primary pancreatic endothelial cells. RESULTS: Results show that hpaECMs can be successfully and consistently produced from human pancreata and maintain their innate molecular and spatial framework and stiffness, and vital growth factors. Importantly, hpaECMs inhibit human naïve CD4 T-cell expansion in response to polyclonal stimuli by inducing their apoptosis and promoting their conversion into regulatory T cells. hpaECMs are cytocompatible and supportive of representative pancreatic cell types. DISCUSSION: We, therefore, conclude that hpaECMs has the potential to become an ideal platform for investigations aiming at the manufacturing of a regenerative medicine-inspired bioartificial endocrine pancreas.
Asunto(s)
Matriz Extracelular/metabolismo , Páncreas , Ingeniería de Tejidos , Andamios del Tejido , Humanos , Islotes Pancreáticos/metabolismo , Organogénesis , Páncreas/metabolismo , Regeneración , Ingeniería de Tejidos/métodosRESUMEN
PURPOSE: Cellular therapy induced transient urodynamic improvement in a rat model of Parkinson disease in which bladder dysfunction was noted after unilateral injection of 6-hydroxydopamine into the medial forebrain bundle. We sought to prolong the effect by injecting allogeneic rat bone marrow mesenchymal stromal cells before and after microencapsulation into the substantia nigra pars compacta. MATERIALS AND METHODS: Female rats underwent unilateral stereotactic injection of 6-hydroxydopamine in the medial forebrain bundle. Injection was performed in the ipsilateral substantia nigra pars compacta using vehicle alone or vehicle with nonmicroencapsulated or microencapsulated rat bone marrow derived mesenchymal stromal cells. Rats were evaluated by cystometry 7, 14, 28 and 42 days after treatment. Brains were extracted for immunostaining. RESULTS: At 42 days the nonmicroencapsulated group had lower threshold and intermicturition pressure, spontaneous activity and AUC than vehicle treated animals. Rats that received microencapsulated cells had lower threshold pressure at 28 days and lower spontaneous activity at 42 days than vehicle treated rats. Microencapsulated and nonmicroencapsulated rat bone marrow derived mesenchymal stromal cells were noted in the substantia nigra pars compacta up to 42 days after transplantation. At 42 days tyrosine hydroxylase positive neurons were more numerous in the substantia nigra pars compacta of the nonmicroencapsulated group, followed by the microencapsulated and vehicle treated groups. CONCLUSIONS: Urodynamic effects of the 6-hydroxydopamine lesion persisted up to 42 days after vehicle injection. Transplantation of nonmicroencapsulated rat bone marrow derived mesenchymal stromal cells improved urodynamic pressure by 42 days after treatment more markedly than microencapsulated cells. This was associated with more tyrosine hydroxylase positive neurons in the treated substantia nigra pars compacta of the nonmicroencapsulated group, suggesting that functional improvement requires a juxtacrine effect.
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Médula Ósea/fisiopatología , Tratamiento Basado en Trasplante de Células y Tejidos , Trasplante de Células Madre Mesenquimatosas , Enfermedad de Parkinson/fisiopatología , Enfermedad de Parkinson/terapia , Urodinámica , Animales , Modelos Animales de Enfermedad , Femenino , Citometría de Flujo , Inmunohistoquímica , Microscopía Confocal , Oxidopamina , Ratas , Ratas Sprague-Dawley , Sustancia Negra/fisiopatologíaRESUMEN
In recent years, great advances have been made in the use of islet transplantation as a treatment for type I diabetes. Indeed, it is possible that stimulation of local neovascularization upon transplantation could improve functional graft outcomes. In the present study, we investigate the use of multilayered alginate microbeads to provide a sustained delivery of FGF-1, and whether this results in increased neovascularization in vivo. Multilayered alginate microbeads, loaded with either 150ng or 600ng of FGF-1 in the outer layer, were surgically implanted into rats using an omentum pouch model and compared to empty microbead implants. Rats were sacrificed at 4days, 1week, and 6weeks. Staining for CD31 showed that both conditions of FGF-1 loaded microbeads resulted in a significantly higher vessel density at all time points studied. Moreover, at 6weeks, alginate microbeads containing 600ng FGF-1 provided a greater vascular density compared to both the control group and the microbeads loaded with 150ng FGF-1. Omenta analyzed via staining for smooth muscle alpha actin showed no variation in mural cell density at either 4days or 1week. At 6weeks, however, omenta exposed to microbeads loaded with 600ng FGF-1 showed an increase in mural cell staining compared to controls. These results suggest that the sustained delivery of FGF-1 from multilayered alginate microbeads results in a rapid and persistent vascular response. An increase in the local blood supply could reduce the number of islets required for transplantation in order to achieve clinical efficacy.
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Alginatos/química , Inductores de la Angiogénesis/farmacología , Portadores de Fármacos , Factor 1 de Crecimiento de Fibroblastos/farmacología , Neovascularización Fisiológica/efectos de los fármacos , Epiplón/irrigación sanguínea , Actinas/metabolismo , Inductores de la Angiogénesis/administración & dosificación , Inductores de la Angiogénesis/química , Animales , Biomarcadores/metabolismo , Preparaciones de Acción Retardada , Células Endoteliales/efectos de los fármacos , Células Endoteliales/metabolismo , Factor 1 de Crecimiento de Fibroblastos/administración & dosificación , Factor 1 de Crecimiento de Fibroblastos/química , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/metabolismo , Miocitos del Músculo Liso/efectos de los fármacos , Miocitos del Músculo Liso/metabolismo , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Ratas , Ratas Sprague-Dawley , Factores de TiempoRESUMEN
Islet transplantation has been shown to be a viable treatment option for patients afflicted with type 1 diabetes. However, the lack of availablity of human pancreases and the need to use risky immunosuppressive drugs to prevent transplant rejection remain two major obstacles to the routine use of islet transplantation in diabetic patients. Successful development of a bioartificial pancreas using the approach of microencapsulation with perm-selective coating of islets in hydrogels for graft immunoisolation holds tremendous promise for diabetic patients because it has great potential to overcome these two barriers. In this review article, we will discuss the need for a bioartificial pancreas, provide a detailed description of the microencapsulation process, and review the status of the technology in clinical development. We will also critically review the various factors that will need to be taken into consideration in order to achieve the ultimate goal of routine clinical application.
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Diabetes Mellitus Tipo 1/terapia , Composición de Medicamentos/métodos , Páncreas Artificial , Páncreas/fisiología , Alginatos/química , Ácido Glucurónico/química , Rechazo de Injerto/prevención & control , Ácidos Hexurónicos/química , Humanos , Trasplante de Islotes PancreáticosRESUMEN
There is an unrelenting interest in the development of a reliable bioartificial pancreas construct since the first description of this technology of encapsulated islets by Lim and Sun in 1980 because it promised to be a curative treatment for Type 1 Diabetes Mellitus (T1DM). Despite the promise of the concept of encapsulated islets, there are still some challenges that impede the full realization of the clinical potential of the technology. In this review, we will first present the justification for continued research and development of this technology. Next, we will review key barriers that impede progress in this field and discuss strategies that can be used to design a reliable construct capable of effective long-term performance after transplantation in diabetic patients. Finally, we will share our perspectives on areas of additional work for future research and development of the technology.
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Lower urinary tract dysfunction (LUTD) encompasses a range of debilitating conditions that affect both sexes and different age groups. Understanding the underlying neurobiological mechanisms contributing to LUTD has emerged as a critical avenue for the development of targeted therapeutic strategies. Brain-derived neurotrophic factor (BDNF), a prominent member of the neurotrophin family, has attracted attention due to its multiple roles in neural development, plasticity, and maintenance. This review examines the intricate interplay between neurobiological factors and LUTD, focusing on the central involvement of BDNF. The review emphasizes the bidirectional relationship between LUTD and BDNF and explores how LUTD-induced neural changes may affect BDNF dynamics and vice versa. Growth factor therapy and the combined administration of controlled release growth factors and stem cells are minimally invasive treatment strategies for neuromuscular injury. Among the many growth factors and cytokines, brain-derived neurotrophic factor (BDNF) plays a prominent role in neuromuscular repair. As an essential neurotrophin, BDNF is involved in the modulation of neuromuscular regeneration through tropomyosin receptor kinase B (TrkB). Increasing BDNF levels facilitates the regeneration of the external urethral sphincter and contributes to the regulation of bladder contraction. Treatments targeting the BDNF pathway and sustained release of BDNF may become novel treatment options for urinary incontinence and other forms of lower urinary tract dysfunction. This review discusses the applications of BDNF and the theoretical basis for its use in the treatment of lower urinary tract dysfunction, including urinary incontinence (UI), overactive bladder (OAB), and benign prostatic hyperplasia (BPH), and in the clinical diagnosis of bladder dysfunction.
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Tissue-engineering and cell-based strategies provide an intriguing approach to treat complex conditions such as those of the endocrine system. We have previously developed a cell-based hormone therapy (cHT) to address hormonal insufficiency associated with the loss of ovarian function. To assess how the cHT strategy may achieve its efficacy, we developed a mathematical model to determine if known autocrine, paracrine, and endocrine effects of the native hypothalamus-pituitary-ovary (HPO) axis could explain our previously observed effects in ovariectomized rats following treatment with cHT. Our model suggests that cHT constructs participate in the complex machinery of the HPO axis. We were able to describe the in vivo behaviors of estrogen, progesterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), inhibin, and androgen with good accuracy. A sensitivity analysis indicated that some parameters impact the broader HPO system more than others, but that most changes in model parameters led to proportional changes in the system. We also conducted a predictive analysis on the effect of cHT dose on HPO axis hormones and found that, with the exception of estrogen, the other HPO hormones analyzed reach a saturation level within the physically possible number of constructs.
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A strategy that seeks to combine the biophysical properties of inert encapsulation materials like alginate with the biochemical niche provided by pancreatic extracellular matrix (ECM)-derived biomaterials, could provide a physiomimetic pancreatic microenvironment for maintaining long-term islet viability and function in culture. Herein, we have demonstrated that incorporating human pancreatic decellularized ECM within alginate microcapsules results in a significant increase in Glucose Stimulation Index (GSI) and total insulin secreted by encapsulated human islets, compared to free islets and islets encapsulated in only alginate. ECM supplementation also resulted in long-term (58 days) maintenance of GSI levels, similar to that observed in free islets at the first time point (day 5). At early time points in culture, ECM promoted gene expression changes through ECM- and cell adhesion-mediated pathways, while it demonstrated a mitochondria-protective effect in the long-term. STATEMENT OF SIGNIFICANCE: The islet isolation process can damage the islet extracellular matrix, resulting in loss of viability and function. We have recently developed a detergent-free, DI-water based method for decellularization of human pancreas to produce a potent solubilized ECM. This ECM was added to alginate for microencapsulation of human islets, which resulted in significantly higher stimulation index and total insulin production, compared to only alginate capsules and free islets, over long-term culture. Using ECM to preserve islet health and function can improve transplantation outcomes, as well as provide novel materials and platforms for studying islet biology in microfluidic, organ-on-a-chip, bioreactor and 3D bioprinted systems.
Asunto(s)
Trasplante de Islotes Pancreáticos , Islotes Pancreáticos , Humanos , Secreción de Insulina , Páncreas/metabolismo , Insulina/farmacología , Matriz Extracelular/metabolismo , Alginatos/farmacologíaRESUMEN
Current applications of the microencapsulation technique include the use of encapsulated islet cells to treat Type 1 diabetes, and encapsulated hepatocytes for providing temporary but adequate metabolic support to allow spontaneous liver regeneration, or as a bridge to liver transplantation for patients with chronic liver disease. Also, microcapsules can be used for controlled delivery of therapeutic drugs. The two most widely used devices for microencapsulation are the air-syringe pump droplet generator and the electrostatic bead generator, each of which is fitted with a single needle through which droplets of cells suspended in alginate solution are produced and cross-linked into microbeads. A major drawback in the design of these instruments is that they are incapable of producing sufficient numbers of microcapsules in a short-time period to permit mass production of encapsulated and viable cells for transplantation in large animals and humans. We present in this paper a microfluidic approach to scaling up cell and protein encapsulations. The microfluidic chip consists of a 3D air supply and multi-nozzle outlet for microcapsule generation. It has one alginate inlet and one compressed air intlet. The outlet has 8 nozzles, each having 380 micrometers inner diameter, which produce hydrogel microspheres ranging from 500 to 700 µm in diameter. These nozzles are concentrically surrounded by air nozzles with 2 mm inner diameter. There are two tubes connected at the top to allow the air to escape as the alginate solution fills up the chamber. A variable flow pump 115 V is used to pump alginate solution and Tygon® tubing is used to connect in-house air supply to the air channel and peristaltic/syringe pump to the alginate chamber. A pressure regulator is used to control the flow rate of air. We have encapsulated islets and proteins with this high throughput device, which is expected to improve product quality control in microencapsulation of cells, and hence the outcome of their transplantation.
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Células Inmovilizadas/trasplante , Islotes Pancreáticos/metabolismo , Técnicas Analíticas Microfluídicas/instrumentación , Técnicas Analíticas Microfluídicas/métodos , Alginatos/metabolismo , Animales , Técnicas de Cultivo de Célula , Enfermedad Crónica , Diabetes Mellitus Tipo 1/terapia , Sistemas de Liberación de Medicamentos/métodos , Diseño de Equipo/métodos , Ácido Glucurónico/metabolismo , Ácidos Hexurónicos/metabolismo , Islotes Pancreáticos/citología , Hepatopatías/terapia , Trasplante de Hígado , Microesferas , RatasRESUMEN
Alginate microbeads have been investigated clinically for a number of therapeutic interventions, including drug delivery for treatment of ischemic tissues, cell delivery for tissue regeneration, and islet encapsulation as a therapy for type I diabetes. The physical properties of the microbeads play an important role in regulating cell behavior, protein release, and biological response following implantation. In this research alginate microbeads were synthesized, varying composition (mannuronic acid to guluronic acid ratio), concentration of alginate and needle gauge size. Following synthesis, the size, volume fraction, and morphometry of the beads were quantified. In addition, these properties were monitored over time in vitro in the presence of varying calcium levels in the microenvironment. The initial volume available for solute diffusion increased with alginate concentration and mannuronic (M) acid content, and bead diameter decreased with M content but increased with needle diameter. Interestingly, microbeads eroded completely in saline in less than 3 weeks regardless of synthesis conditions much faster than what has been observed in vivo. However, microbead stability was increased by the addition of calcium in the culture medium. Beads synthesized with low alginate concentration and high G content exhibited a more rapid change in physical properties even in the presence of calcium. These data suggest that temporal variations in the physical characteristics of alginate microbeads can occur in vitro depending on synthesis conditions and microbead environment. The results presented here will assist in optimizing the design of the materials for clinical application in drug delivery and cell therapy.
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Alginatos/química , Materiales Biocompatibles/química , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Técnicas In Vitro , Proteínas/químicaRESUMEN
Exosomes are enclosed within a single outer membrane and exemplify a specific subtype of secreted vesicles. Exosomes transfer signalling molecules, including microRNAs (miRNAs), messenger RNA (mRNA), fatty acids, proteins, and growth factors, making them a promising therapeutic tool. In routine bioartificial pancreas fabrication, cells are immobilized in polymeric hydrogels lacking attachment capability for cells and other biological cues. In this opinion article, we will discuss the potential role that exosomes and their specific biofactors may play to improve and sustain the function of this bioartificial construct. We will particularly discuss the challenges associated with their isolation and characterization. Since stem cells are an attractive source of exosomes, we will present the advantages of using exosomes in place of stem cells in medical devices including the bioartificial pancreas. We will provide literature evidence of active biofactors in exosomes to support their incorporation in the matrix of encapsulated islets. This will include their potential beneficial effect on hypoxic injury to encapsulated islets. In summary, we propose that the biofactors contained in secreted exosomes have significant potential to enhance the performance of islets encapsulated in polymeric material hydrogels with perm-selective properties to provide immunoisolation for islet transplants as an insulin delivery platform in diabetes.
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Diabetes Mellitus Tipo 1 , Exosomas , Trasplante de Islotes Pancreáticos , Alginatos , Diabetes Mellitus Tipo 1/terapia , Humanos , Hidrogeles , PáncreasRESUMEN
In this research we have used different cytokines and progesterone to enhance the immunomodulatory capacity of placental-derived stem cells (PLSCs) prior to their encapsulation. We assessed the effect of microencapsulation of the cells without (control) or after 3-day treatment with interferon gamma (INFγ), interleukin10 (IL-10), or progesterone (P4). Treated PLSCs demonstrated strong immunosuppressive effects on phytohemagglutinin (PHA)-activated peripheral blood mononuclear cells (PBMNCs). INFγ treatment resulted in the strongest immune inhibition among the treated groups. The treatments enhanced soluble human leukocyte antigen (sHLAG) secretion compared to control. The IL-10-treated group showed the highest effect on HLAG secretion compared to other groups. Alginate encapsulation of PLSCs did not affect cell viability, or sHLAG secretion. Also, after treatment the encapsulated PLSCs inhibited PHA-activated PBMNCs in the same manner as unencapsulated cells. We studied two groups of encapsulated PLSCs, one without perm-selective poly-L-ornithine (PLO)-coating and the other with PLO-coating, and measured levels of sHLAG secreted. We found no difference in sHLAG secretion between both groups. In summary, our data show that immunomodulatory function of the PLSC is not affected by encapsulation. These findings provide good promise for potential use of encapsulated PLSCs for immunomodulation treatment of disease by stem cell therapy.
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Arginina/análogos & derivados , Interleucina-2/metabolismo , Leucocitos Mononucleares/metabolismo , Arginina/metabolismo , Proliferación Celular , Femenino , Humanos , Trasplante de Células Madre Mesenquimatosas , Células Madre Mesenquimatosas/metabolismo , Placenta/metabolismo , EmbarazoRESUMEN
In this minireview, we briefly outline the hallmarks of diabetes, the distinction between type 1 and type 2 diabetes, the global incidence of diabetes, and its associated comorbidities. The main goal of the review is to highlight the great potential of encapsulated pancreatic islet transplantation to provide a cure for type 1 diabetes. Following a short overview of the different approaches to islet encapsulation, we provide a summary of the merits and demerits of each approach of the encapsulation technology. We then discuss various attempts to clinical translation with each model of encapsulation as well as the factors that have mitigated the full clinical realization of the promise of the encapsulation technology, the progress that has been made and the challenges that remain to be overcome. In particular, we pay significant attention to the emerging strategies to overcome these challenges. We believe that these strategies to enhance the performance of the encapsulated islet constructs discussed herein provide good platforms for additional work to achieve successful clinical translation of the encapsulated islet technology.
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Diabetes Mellitus Tipo 1/terapia , Trasplante de Islotes Pancreáticos/métodos , HumanosRESUMEN
Interactions between the pancreatic extracellular matrix (ECM) and islet cells are known to regulate multiple aspects of islet physiology, including survival, proliferation, and glucose-stimulated insulin secretion. Recognizing the essential role of ECM in islet survival and function, various engineering approaches have been developed that aim to utilize ECM-based materials to recreate a native-like microenvironment. However, a major impediment to the success of these approaches has been the lack of a robust and comprehensive characterization of the human pancreatic proteome. Herein, by combining mass spectrometry (MS) and multiplex ELISA, we have provided an improved workflow for the in-depth profiling of the proteome, including minor constituents that are generally underrepresented. Moreover, we have further validated the effectiveness of our detergent-free decellularization protocol in the removal of cellular proteins and retention of the matrisome. It has also been established that the decellularized ECM and its derivatives can provide more tissue-specific cues than traditionally used biological scaffolds and are therefore more physiologically relevant for the development of hydrogels, bioinks and medium additives, in order to create a pancreatic niche. The data generated in this study would contribute significantly to the efforts of comprehensively defining the ECM atlas and also serve as a standard for the human pancreatic proteome to provide further guidance for design and engineering strategies for improved tissue engineering scaffolds.
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Matriz Extracelular , Proteoma , Humanos , Páncreas , Ingeniería de Tejidos , Andamios del TejidoRESUMEN
BACKGROUND: Growth of new blood vessels (neovascularization) occurs naturally in the body, but the slow rate of the process may not be sufficient for survival of engineered tissues and transplanted cells, such as pancreatic islets. For transplanted islets, it is crucial that the transplantation site has sufficient vasculature to support the needs of the islets. Therefore, the specific aim of this research was quantify the effect of FGF-1 incorporation into alginate microbeads on neovascularization of such capsules in an in vivo rat transplant model. MATERIALS AND METHODS: Microbeads loaded with FGF-1 or control beads (beads without FGF-1) were implanted in the rat omental pouch model. Animals were sacrificed 7 d post-implantation. RESULTS: Microbeads loaded with FGF-1 stimulated a significant increase in vascular density compared with control rats implanted with control beads. CONCLUSIONS: These results indicate that alginate microbeads loaded with FGF-1 enhance local neovascularization around implanted microbeads. These data provide a compelling impetus for experimental pursuit of FGF-loaded alginate microcapsules for vascularization of transplanted islets.
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Capilares/fisiología , Factor 1 de Crecimiento de Fibroblastos/farmacología , Trasplante de Islotes Pancreáticos/métodos , Neovascularización Fisiológica/efectos de los fármacos , Epiplón/irrigación sanguínea , Ingeniería de Tejidos/métodos , Alginatos , Animales , Capilares/efectos de los fármacos , Ácido Glucurónico , Ácidos Hexurónicos , Microesferas , Modelos Animales , Epiplón/citología , Ratas , Ratas Endogámicas LewRESUMEN
BACKGROUND: There is a significant interest in effective oral drug delivery of therapeutic substances. For probiotics, there is a particular need for a delivery platform that protects the bacteria from destruction by the acidic stomach while enabling targeted delivery to the intestine where microbiota naturally reside. The use of probiotics and how they impact the gut microbiota is a growing field and holds promise for the treatment of a variety of gastrointestinal diseases, including irritable bowel disease Crohn's disease and C. diff and other diseases, such as obesity, diabetes, Parkinson's, and Alzheimer's diseases. OBJECTIVE: The aim of this research was to use our newly developed chemically-modified alginate hydrogel with the characteristic feature of stability in acidic environments but disintegration under neutral-basic pH conditions to design a novel system for effective targeted delivery of ingested probiotics. METHODS AND RESULTS: We have used the approach of encapsulation of bacterial cells in the hydrogel of the modified alginate with in vitro studies in both simulated stomach acid and intestinal fluid conditions to demonstrate the potential application of this novel platform in oral delivery of probiotics. Our data provide a proof-of-concept that enables further studies in vivo with this delivery platform. CONCLUSION: We have demonstrated in the present study that our chemically modified alginate hydrogel is resistant to acidic conditions and protects bacterial cells encapsulated in it, but it is sensitive to neutral-basic pH conditions under which it disintegrates and releases its viable bacteria cell payload. Our data provide a proof-ofconcept that enables further studies in vivo with this delivery platform for the efficacy of therapeutic bacteria in various disease conditions.
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Probióticos , Alginatos , Excipientes , Humanos , Hidrogeles , Concentración de Iones de HidrógenoRESUMEN
To support the increasing translational use of transplanted cells, there is a need for high-throughput cell encapsulation technologies. Microfluidics is a particularly promising candidate technology to address this need, but conventional polydimethylsiloxane devices have encountered challenges that have limited their utility, including clogging, leaking, material swelling, high cost, and limited scalability. Here, we use a rapid prototyping approach incorporating patterned adhesive thin films to develop a reusable microfluidic device that can produce alginate hydrogel microbeads with high-throughput potential for microencapsulation applications. We show that beads formed in our device have high sphericity and monodispersity. We use the system to demonstrate effective cell encapsulation of mesenchymal stem cells and show that they can be maintained in culture for at least 28 days with no measurable reduction in viability. Our approach is highly scalable and will support diverse translational applications of microencapsulated cells.