Objective
The objective of this research is to assess the potential of a novel platform designed for subcutaneous islet transplantation. The subcutaneous site, while the most accessible in a clinical setting, presents challenges such as limited vascularization and low oxygen concentrations, making it less favorable for densely packed islet cell grafts. The research aims to overcome these limitations by investigating a groundbreaking approach that combines pro-angiogenic peptide-loaded hydrogels with an oxygen generation system.
The proposed platform seeks to promote vascular network formation within the hydrogel, facilitated by the pro-angiogenic peptides, while simultaneously enhancing the long-term viability of encapsulated islets using the oxygen generator within the 3D hydrogel carrier. These vascularizing 3D printed cell carriers, once loaded with islet cells, will be implanted into the subcutaneous space. The overarching goal of this 3-year project is to evaluate the capabilities of this innovative cell carrier specifically in supporting the long-term survival of autologous rat islets in the subcutaneous site. The project aims to achieve physiologically necessary glucose-stimulated insulin secretion kinetics addressing issues such as early graft failure due to delayed vascularization and subsequent hypoxia in transplantation scenarios. The utilization of STZ-treated Sprague Dawley rats in this study will provide valuable insights into the success and viability of the proposed platform for subcutaneous islet transplantation.
Background Rationale
The prevailing treatment for T1D involves meticulous routine of blood glucose monitoring, exogenous insulin administration, and dietary modifications. Despite the remarkable progress in T1D treatment technologies, the ability to attain target glycemic levels for patients suffering from T1D remains low, underscoring the need for a more effective approach. Beta cell replacement therapy emerges as the potential cure for T1D, capitalizing on recent strides in stem cell differentiation technologies. These advancements enable the development of a replenishable source of clinical beta cells. While studies have explored various transplantation sites (hepatic portal vein, omentum, intramuscular, and subcutaneous), optimization is imperative to enhance islet graft survival. Additionally, the success of islet transplantation is hampered by oxygen and nutrient deficiencies at the transplantation site, inhibiting allo- or xenogeneic transplantation. Oxygen, a critical factor for cell viability, faces constraints such as insufficient tension, high consumption, and barriers to diffusion. Strategies to enhance exogenous oxygen delivery include gaseous oxygen or engineered platforms, but limitations persist in control, supply lifetime, and cell density support. EcO2 emerges as a promising alternative approach. Recent breakthroughs in bioelectronics, such as ecO2, demonstrate the potential for implantable oxygenators for pancreatic islet transplantation. EcO2 addresses challenges associated with oxygenation by maintaining high-density cell loaded therapies and supporting densely packed cells and tissues, crucial for sustained bioactivities.
Vascularization, essential for nutrient and oxygen access, is often delayed in current implantable platforms, leading to initial transplantation failure. The subcutaneous space, despite its accessibility, poses challenges due to low basal oxygen concentration and inferior diffusivity. Early oxygenation and complementary vascularization strategies are deemed promising for transplanted pancreatic islets. Vascularization remains an unmet need in islet transplantation. The natural pancreas relies on a dense vascular network to supply nutrients and oxygen to nearby islets, ensuring effective insulin secretion for blood glucose regulation. Current efforts, including decellularization, face challenges in maintaining the desired vascular network for islet integration, emphasizing the critical gap in scaffold fabrication for vascularized islet constructs in clinical translation.
Our previous publication in Science Advances, showcasing the 3D printing of gelatin-based hydrogels with subsequent implantation in rodent models, resulted in the generation of mature vasculature within the hydrogels. Building upon this success, the integration of the oxygen generator from Rivnay and Cohen-Karni labs presents a novel solution for islet transplantation. Therefore, the proposed research aims to address the identified challenges by investigating a novel platform that combines both the pro-angiogenic peptide-loaded hydrogels with the oxygen-generating system. By promoting vascular network formation within the hydrogel and improving the long-term viability of transplanted islets, this innovative 3D-printed cell carrier is designed for subcutaneous islet transplantation. The three-year project seeks to evaluate the platform’s capabilities in supporting the long-term survival of autologous rat islets and achieving physiologically necessary glucose-stimulated secretion kinetics, thereby advancing the field of islet transplantation for T1D.
Description of Project
Type 1 Diabetes (T1D) is a chronic condition characterized by the immune system's destruction of insulin-producing beta cells in the pancreas, necessitating a lifelong reliance on exogenous insulin along with strict blood glucose monitoring, insulin administration, and dietary modifications. While there have been significant advancements in treating T1D, challenges persist with only 17% of children and adolescents meeting target glycemic levels. Therefore, the goal in diabetes treatment is achieving insulin dependency, often pursued through islet transplantation.
Islet transplantation, aiming to replace damaged pancreatic cells, faces obstacles such as the need for immunosuppression and challenges in providing adequate oxygen and nutrients. Oxygen plays a crucial role in supporting cell viability and function, and transplanting islets requires formation of new blood vessels or supplemental oxygenation. Unfortunately, current approaches face difficulties due to hypoxic stress to transplanted cells, caused by factors like insufficient oxygen tension, high cell density, and barriers to oxygen diffusion. Various strategies have been explored to enhance oxygen delivery to transplanted cells. These include active methods, such as delivering gaseous oxygen and passive methods, involving engineered platforms or the release of oxygen from materials. While these approaches can support transplanted cells, they have limitations in controlling oxygen release, the lifespan of the supply, and cell density support.
Vascularization, the formation of new blood vessels, is crucial for ensuring proper access to nutrients and oxygen. However, current implantable platforms often experience delays in vascularization, leading to transplantation failure. Therefore, transplanted therapeutic tissues and cells require exogenous supply of nutrients and oxygen, with oxygen being the most limiting factor.
The proposed solution involves electrochemical water electrolysis for oxygen production, specifically electrocatalytic on-site oxygenation (ecO2). This approach, demonstrated in vitro and in vivo, aims to sustain high-density cell therapies, offering a promising avenue for a miniaturized and implantable solution for pancreatic islet transplantation for T1D patients. The innovation lies in a highly controlled on-demand ecO2 platform that enhances oxygen production efficiency. We propose a novel 3D-printed hydrogel islet carrier design to integrate and localize the ecO2 platform to transplanted islets. This hydrogel carrier aims to support transplanted pancreatic islets, by incorporating an ecO2 conduit next to the hydrogel. To ensure the long-term viability of encapsulated tissues, the 3D-printed carrier includes additional channels perfused with a pro-angiogenic peptide that promotes blood vessel growth and infiltration into the hydrogel carrier, offering an enduring support for islets to achieve glycemic correction.
In summary, the research addresses critical challenges in diabetes treatment, focusing on enhancing oxygen supply to transplanted cells through an innovative ecO2 platform integrated with vascularizing 3D-printed cell carrier. The goal is to create a sustainable, implantable solution for pancreatic islet transplantation, in hopes of paving the way for improved outcomes in treating T1D.
Anticipated Outcome
In the pursuit of Aim 1, our objective is to engineer electrocatalytic on-site oxygenation (ecO2) capable of supporting high-density cells embedded in a 3D hydrogel, simulating the vascularization delay for 2-3 weeks in vitro. The preliminary data strongly supports the hypothesis that ecO2 can efficiently sustain high cell loading (approximately 4.7 million cells/cm2). Additionally, the flexible nature of our approach allows us to increase the number of oxygenation sites, mitigating the risk and ensuring adequate oxygen supply to the 3D tissues. Therefore, we highly anticipate that the ecO2 device will enable oxygenation diffusion throughout a 3D hydrogel matrix and support both rodent and human pancreatic islet functionality and survival in vitro. In Aim 2, our goal is to demonstrate that the integration of a vascularizing system, comprising a gelatin-based 3D printed hydrogel, pro-angiogenic peptide, and an oxygen generation platform, can facilitate prolonged islet viability in vivo. Given the substantial expertise of our research team in the proposed procedures and methodologies, we anticipate successful execution of our proposed work with minimal technical challenges. The utilization of DLP 3D printing of GelMA bioinks, coupled with the oxygen generator platform, positions our research at the forefront of the field.
If successful, the combination of 3D-printed gelatin-based hydrogels, a vascularizing pro-angiogenic peptide, and the ecO2 oxygen generator holds transformative potential for islet transplantation. This innovative approach offers short-term islet support within a vascularizing environment, allowing for the long-term survival of islets. The culmination of these efforts has the capacity to revolutionize therapeutic solutions for patients suffering with T1D. As we progress, we remain poised to contribute significant advancements to the field of islet transplantation, paving the way for improved outcomes and potential cures for T1D patients.
Relevance to T1D
The proposed work directly addresses the limitations and challenges that have hindered the widespread success of islet transplantation for T1D. By enhancing oxygenation during the critical early stages and promoting prolonged viability in vivo, the research seeks to significantly improve the outcomes of islet transplantation. If successful, this innovative approach has the potential to provide a transformative therapeutic solution for patients afflicted with T1D. It aims to offer not only short-term islet support within a vascularizing environment but also the long-term survival of transplanted islets, marking a significant leap forward in the pursuit of a cure for T1D.
In conclusion, the research's relevance for T1D lies in its potential to overcome existing challenges, enhance the success of islet transplantation, and contribute to the development of a more effective and sustainable therapeutic solution for T1D patients. As the research progresses, it holds the promise of advancing the field, bringing us closer to realizing a cure for T1D through innovative and transformative approaches.