Microchip-based engineering of super-pancreatic islets supported by adipose-derived stem cells

Engineered in vitro disease models

The ultimate goal of most biomedical research is to gain greater insight into mechanisms of human disease or to develop new and improved therapies or diagnostics. Although great advances have been made in terms of developing disease models in animals, such as transgenic mice, many of these models fail to faithfully recapitulate the human condition. In addition, it is difficult to identify critical cellular and molecular contributors to disease or to vary them independently in whole-animal models. This challenge has attracted the interest of engineers, who have begun to collaborate with biologists to leverage recent advances in tissue engineering and microfabrication to develop novel in vitro models of disease. As these models are synthetic systems, specific molecular factors and individual cell types, including parenchymal cells, vascular cells, and immune cells, can be varied independently while simultaneously measuring system-level responses in real time. In this article, we provide some examples of these efforts, including engineered models of diseases of the heart, lung, intestine, liver, kidney, cartilage, skin and vascular, endocrine, musculoskeletal, and nervous systems, as well as models of infectious diseases and cancer. We also describe how engineered in vitro models can be combined with human inducible pluripotent stem cells to enable new insights into a broad variety of disease mechanisms, as well as provide a test bed for screening new therapies.

Trophic effects of adipose derived stem cells on Langerhans islets viability--Review

Langerhans islets transplantation has been proposed to provide an endogenous source of insulin in Type I diabetes. However, the hypoxic stress and the receptor's immune reaction suffered by the implants cause them to fail in sustaining the insulin production along the time. Experimental studies have shown that adipose derived stem cells (ADSCs) can secrete cytokines that activate free radical scavengers, antioxidants and chaperone heat/shock proteins leading to reduction of apoptosis in damaged tissues. Therefore, using the PubMed database, we reviewed the experimental studies that investigated the trophic effects of ADSCs on Langerhans islets viability, in vitro and in vivo, from 2009 to 2014. We excluded articles that investigated the effects of other types of mesenchymal stem cells on β-cell survival as well articles that worked in the differentiation of ADSCs into insulin producing cells. The analysis of the experiments revealed that exposure of islets to ADSCs in vitro, even for a short period of time, can enhance islet cell viability and function. In vivo studies also corroborated the trophic effects of ADSCs leading to the improvement of islet function and reduction of the number of the islets required for controlling the receptor's glucose levels. This review can contribute to guide future experiments looking for a long term diabetes treatment employing ADSC trophic effects for the enhancement of transplanted Langerhans islet viability and functioning.

Applicability of Adipose-Derived Stem Cells in Type 1 Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is a form of early onset diabetes mellitus characterized by the autoimmune destruction of insulin-producing cells (IPCs), resulting in hyperglycemia and abnormal glucose metabolism. There are currently no treatments available capable of completely curing the symptoms associated with the loss or functional defects of IPCs. Nonetheless, stem cell therapy has demonstrated considerable promise in the replacement of IPCs with immunomodulatory functions to overcome the defects caused by T1DM. Adipose-derived stem cells (ADSCs) are particularly suitable for use in cell transplantation therapy, especially when seeking to avoid the ethical issues and tumorigenic complications commonly associated with embryos or induced pluripotent stem cells. Cell-based treatments have demonstrated therapeutic advantages and clinical applicability of ADSCs in T1DM, ensuring their suitability for transplantation therapy. This manuscript focuses on the benefits and possible mechanisms in a T1DM-relevant model and displays positive results from finished or ongoing human clinical trials. We also discuss and hypothesize potential methods to further enhance the therapeutic efficacy of these efforts, such as a humanized rodent model and gene therapies for IPC clusters, to meet the clinical applicability of the standard.

In vitro micro-physiological models for translational immunology

The immune system is a source of regulation of the human body and is key for its stable functioning. Animal models have been successfully used for many years to study human immunity and diseases and provided significant contributions to the development of powerful new therapies. However, such models inevitably display differences from the human metabolism and disease state and therefore may correlate poorly with the human conditions. This explains the interest for the use of in vitro models of human cells, which have better potential to assist in understanding the physiological events that characterize the immune response in humans. Microfluidic technologies offer great capabilities to create miniaturized in vivo-like physiological models that mimic tissue-tissue interactions and simulate the body metabolism in both the healthy and diseased states. The micro-scale features of these microfluidic systems allow positioning heterogeneous cellular cultures in close proximity to each other in a dynamic fluidic environment, thereby allowing efficient cell-cell interactions and effectively narrowing the gap between in vivo and in vitro conditions. Due to the relative simplicity of these systems, compared to animal models, it becomes possible to investigate cell signaling by monitoring the metabolites transported from one tissue to another in real time. This allows studying detailed physiological events and in consequence understanding the influence of metabolites on a specific tissue/organ function as well as on the healthy/diseased state modulation. Numerous in vitro models of human organs have been developed during the last few years, aiming to mimic as closely as possible the in vivo characteristics of such organs. This technology is still in its infancy, but is promised a bright future in industrial and medical applications. Here we review the recent literature, in which functional microphysiological models have been developed to mimic tissues and to explore multi-tissue interactions, focusing in particular on the study of immune reactions, inflammation and the development of diseases. Also, an outlook on the opportunities and issues for further translational development of functional in vitro models in immunology will be presented.

Diabetes mellitus and cellular replacement therapy: Expected clinical potential and perspectives

Diabetes mellitus (DM) is the most prevailing disease with progressive incidence worldwide. Despite contemporary treatment type one DM and type two DM are frequently associated with long-term major microvascular and macrovascular complications. Currently restoration of failing β-cell function, regulation of metabolic processes with stem cell transplantation is discussed as complements to contemporary DM therapy regimens. The present review is considered paradigm of the regenerative care and the possibly effects of cell therapy in DM. Reprogramming stem cells, bone marrow-derived mononuclear cells; lineage-specified progenitor cells are considered for regenerative strategy in DM. Finally, perspective component of stem cell replacement in DM is discussed.