Description:
Purpose and Research Objectives:
Despite clear progress made during the last 15 years on cellular transplantation for T1D, the most recent results demonstrate a long-term limited viability of engrafted islets and, as a result, limited insulin independence under different novel modalities of immunosuppressive (IS) regimens tested. In addition, even the most innovative IS regimens required for transplant survival still have significant immediate side effects and long-term safety is uncertain. These problems together with the scarcity of donor organs and the complexity of transplants mandates a renewed emphasis on the investigation of novel methods within the field of tissue engineering for the development of a bio-artificial, cell-based hormone replacement therapy that may minimize the need of IS. To support this, it is necessary to develop/optimize novel/smart/safe biomaterials, scaffolds, bio-matrices and bio-barriers that may protect grafted cells from immune rejection and simultaneously promote appropriate vascularization/innervation with an efficient exchange of nutrients to optimize cellular long-term survival and proper function. It is also necessary to investigate methods to use different cell sources including human progenitor cells and induced pluripotent stem cells as a valid option for cell replacement therapy. Also, further research on the potential use of xenogeneic cells/islets is needed. Recent advances in this field, because of support by NIDDK/NIH and other funding agencies, demonstrate feasibility of these technologies, mainly in rodent pre-clinical models of T1D. However, important obstacles remain before long-term preclinical efficacy in non-human primates (NHP) and human clinical feasibility may be verified. Examples of areas that need further emphasis/development are:
Development of encapsulation systems able to satisfy GMP standards and regulatory agency specifications including strict assurance of sterility, avoidance of bioburden, safety, and reproducibility of a product with adequate quality control measures during manufacture thus making these systems suitable for the clinical application of encapsulated islet technologies. System characteristics may also include: consistency, uniformity and mono-dispersity of hydrogels, defined number of islets per capsule, limited batch to batch variability, complete and gentle encapsulation, minimized time of islets out of culture and scalability.
Development of tools and methods for less invasive approaches for implantation of devices
Development and optimization of novel biomaterials: highly biocompatible, stable, inert, and of a sufficient porosity to not interfere with the encapsulated cell's physiological regulatory response to stimuli in a NHP and/or human environment.
Optimization of longer-term culture and long-term storage methods to improve access to islet cells replacement/transplantation interventions.
Optimization of high-throughput screening for selection of suitable implantable device materials.
Novel methods to test the in vivo biocompatibility of transplanted capsules/devices and the cell preparations.
Generation of biomaterial layers with a bioactive surface capable of actively altering the localized implant environment.
Study feasibility of pre-vascularization of devices before implantation to ensure better cell viability and function.
Agents incorporated in implantable devices to enhance vascularization at the tissue/device interface during the healing process after implantation.
Novel methods/technologies to ensure proper and efficient long-term oxygenation and nutrient delivery to maintain high viability and function of the implanted islets/cells in vivo.
Efficient incorporation of oxygen carrying/generating agents to biomaterials/micro-nano devices.
Characterization of oxygenation, viability and potency of islets or human stem cell derived (beta-cells/islets) within encapsulation devices in vitro and/or in vivo.
Non-invasive assessment of pO2 within devices and at transplant sites – at multiple time points prior to and post-transplant (hours/days/weeks/years).
Non-invasive evaluation of cell viability and function within encapsulation devices in vitro and in vitro (e.g., imaging technologies for this purpose).
Devise better standardization methods to rapidly and accurately define viability and functional quality of donor islets and human stem cell-derived beta cells/islets.
Novel biomimetic and immuno-engineering strategies for the development of immune evasive biomaterials/devices effective in an NHP/human environment with no need of systemic immunosuppression.
Bio-immuno-engineering of islets/cells in order to make them resistant to allo/autoimmune rejection without the need of systemic immunosuppression
Elucidation of factors/mechanisms that lead to islet exhaustion and potential interventions to ensure islets' functional capacity.
Development of devices/technologies to facilitate islets implantation in extrahepatic sites including factors that may facilitate functional long-term intraperitoneal implantation.
Optimized methods for storage and shipment of cells/devices for transplantation.
Methods/technologies to improve feasibility of using engineered beta/islet cells, such as human progenitor cells and induced pluripotent stem cells, as sources for T1D cell replacement therapy able to induce long-term graft acceptance/tolerance.
Development of techniques to maintain and expand human islets and physiologically responsive insulin-producing cells derived from stem/progenitor cells to make them suitable for cell replacement and disease modeling.
Development of protocols for standardization of cell sources as reagents - pig cells, human stem cell derived progenitors and functional beta-like cells/islets/preps.
Novel in vitro and in vivo pre-clinical disease models such as biomimetic/humanized that may better predict human responses to cells and material/devices.
Non-invasive assessment of vascularization and blood flow around implanted encapsulation devices, especially in conjunction with functional (oxygen) measurements.
