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Diabetes mellitus represents one of the most pressing global health challenges of our time, affecting hundreds of millions of people worldwide and imposing significant burdens on healthcare systems, economies, and individual quality of life. Among the various forms of this metabolic disorder, Type 1 diabetes (T1D) stands out as particularly challenging, characterized by the autoimmune destruction of insulin-producing pancreatic beta cells. While conventional treatments such as exogenous insulin administration have saved countless lives, they remain imperfect solutions that cannot fully replicate the sophisticated, real-time glucose regulation provided by healthy beta cells. This fundamental limitation has driven researchers to explore innovative approaches that could restore natural insulin production and potentially cure diabetes rather than merely managing its symptoms.
In recent years, the field of biomaterials science has emerged as a beacon of hope in the quest for more effective diabetes treatments. Engineered bioartificial pancreas have been proposed as innovative therapeutic solutions and modelling systems for diabetes screening and treatment, by integrating cells, biomaterials and advanced technologies. These novel biomaterials are revolutionizing our approach to beta cell therapy by providing protective environments that enhance cell survival, promote proper insulin secretion, and shield transplanted cells from immune rejection. This comprehensive exploration examines how cutting-edge biomaterial innovations are transforming the landscape of diabetes treatment and bringing us closer to a functional cure.
Understanding the Challenge: Why Beta Cells Need Protection
Before delving into the solutions that biomaterials provide, it is essential to understand the complex challenges facing beta cell transplantation and replacement therapies. Pancreatic beta cells are highly specialized endocrine cells located within the islets of Langerhans, small clusters of cells scattered throughout the pancreas. These remarkable cells possess the unique ability to sense blood glucose levels and respond by secreting precisely calibrated amounts of insulin, the hormone responsible for enabling cells throughout the body to absorb and utilize glucose for energy.
In Type 1 diabetes, the immune system mistakenly identifies beta cells as foreign invaders and systematically destroys them through autoimmune attack. This leaves patients unable to produce insulin naturally, requiring lifelong dependence on external insulin administration through injections or pumps. While this treatment prevents immediate life-threatening complications, it cannot perfectly mimic the dynamic, moment-to-moment adjustments that healthy beta cells make in response to changing glucose levels, leading to both short-term complications like hypoglycemia and long-term damage to blood vessels, nerves, kidneys, and eyes.
Islet transplantation has now become a promising treatment for insulin-deficient diabetes mellitus. Compared to traditional diabetes treatments, cell therapy can restore endogenous insulin supplementation, but its large-scale clinical application is impeded by donor shortages, immune rejection, and unsuitable transplantation sites. When researchers attempt to transplant healthy beta cells or pancreatic islets into diabetic patients, they face multiple formidable obstacles. First, the same autoimmune processes that destroyed the original beta cells remain active and will attack newly transplanted cells unless they are protected. Second, even in non-autoimmune contexts, the body’s natural immune system recognizes transplanted cells as foreign tissue and mounts rejection responses. Third, transplanted cells often struggle to survive in their new environment due to inadequate oxygen supply, nutrient deficiencies, and lack of the supportive extracellular matrix that normally surrounds cells in their native tissue.
These challenges have historically required patients receiving islet transplants to take powerful immunosuppressive medications indefinitely, which carry their own serious risks including increased susceptibility to infections, kidney damage, and cancer. Moreover, even with immunosuppression, many transplanted islets fail to survive long-term, with approximately 50% of patients being insulin independent after five years following pancreatic islet transplantation. This is where biomaterials enter the picture as potential game-changers, offering sophisticated solutions to protect, support, and enhance the function of transplanted beta cells.
The Biomaterial Revolution: Creating Protective Microenvironments
Biomaterials designed for beta cell therapy serve multiple critical functions simultaneously. At their core, these materials act as physical barriers that shield transplanted cells from immune attack while remaining permeable enough to allow essential molecules—glucose, oxygen, nutrients, and insulin—to pass through freely. This selective permeability is crucial: the barrier must be tight enough to exclude immune cells and large antibodies but open enough to permit the rapid exchange of small molecules necessary for cell survival and function.
Encapsulation into semipermeable biomaterials provides a strategy that allows nutrients, oxygen and secreted hormones to diffuse through the membrane while blocking immune cells and the like out of the capsule, allowing long-term graft survival and avoiding long-term use of immunosuppression. Beyond simple physical protection, advanced biomaterials are being engineered to actively support beta cell health and function by mimicking the natural cellular microenvironment, delivering therapeutic molecules, modulating immune responses, and promoting vascularization to ensure adequate blood supply.
Researchers have been creating biomimicking environments that support the growth and function of beta cells, replicating the pancreatic extracellular matrix for studying disease mechanisms and developing advanced models for diabetes research. The extracellular matrix (ECM) is the complex network of proteins and carbohydrates that surrounds cells in tissues, providing structural support and biochemical signals that regulate cell behavior. By incorporating ECM components or ECM-mimicking materials into beta cell encapsulation systems, researchers can create environments that feel “familiar” to the cells, promoting their survival, proper organization, and optimal function.
Hydrogels: Water-Rich Polymers That Mimic Natural Tissue
Among the various biomaterial platforms being explored for beta cell therapy, hydrogels have emerged as particularly promising candidates. Hydrogels are three-dimensional polymer networks that can absorb and retain large amounts of water—often more than 90% of their total weight—while maintaining their structural integrity. This high water content gives hydrogels physical properties remarkably similar to natural soft tissues, making them ideal for creating cell-friendly environments.
Natural Hydrogels: Harnessing Biology’s Own Materials
Natural-based biomaterials have emerged as promising candidates due to their inherent biocompatibility and ability to mimic the extracellular matrix (ECM) of the pancreas. Natural hydrogels are derived from biological sources and include materials such as alginate, collagen, hyaluronic acid, and silk fibroin. These materials offer excellent biocompatibility because they are composed of molecules that the body recognizes as natural or similar to natural substances, reducing the likelihood of adverse reactions.
Alginate, extracted from brown seaweed, has been one of the most extensively studied materials for islet encapsulation. It forms gels rapidly when exposed to divalent cations like calcium, allowing cells to be gently encapsulated under mild conditions that don’t harm them. Biomaterials such as alginate and polyethylene glycol-based hydrogels have improved mechanical stability and biocompatibility of the pancreatic scaffolds, while minimizing the foreign body response. Alginate capsules can be produced in various sizes, from nanoscale coatings to microscale beads to macroscale devices, offering flexibility in design and application.
Collagen, a major structural protein in various tissues, is also used due to its exceptional biocompatibility and ability to be cross-linked in various ways. As the most abundant protein in the human body, collagen provides natural cell-binding sites that promote cell adhesion and can be enzymatically remodeled by cells, allowing them to reshape their immediate environment. This dynamic interaction between cells and collagen scaffolds can enhance cell survival and function.
Hyaluronic acid, a major component of the extracellular matrix, has also shown promise in beta cell encapsulation. Research has demonstrated that hyaluronic acid enhances cell survival of encapsulated insulin-producing cells in alginate-based microcapsules, suggesting that combining multiple natural materials can leverage the beneficial properties of each component.
Silk fibroin is also a promising material for cell therapy, supporting cell growth and differentiation while maintaining its structural integrity and biocompatibility over time. Derived from silkworm cocoons, silk fibroin offers remarkable mechanical strength combined with excellent biocompatibility and can be processed into various forms including hydrogels, films, and porous scaffolds.
Synthetic Hydrogels: Precision-Engineered Protection
While natural hydrogels offer excellent biocompatibility, synthetic hydrogels provide researchers with unprecedented control over material properties. Synthetic-based biomaterials are versatile and offer a tailored control over physicochemical properties of cell-encapsulating materials in terms of porosity, flexibility and stability. Moreover, the inert properties and high reproducibility of synthetic-based biomaterials allows for more efficient cell/islet-encapsulation performances with reduced risks of immune response after encapsulation.
Polyethylene glycol (PEG) is one of the most widely used synthetic polymers for cell encapsulation. PEG hydrogels, known for their immunoprotected properties, create a protective barrier around islets, shielding them from the immune system and promoting long-term survival. PEG is highly resistant to protein adsorption and cell adhesion, which helps prevent the foreign body response—the inflammatory reaction that occurs when the immune system detects implanted materials. This “stealth” property makes PEG-based materials particularly valuable for creating immunoprotective barriers.
Researchers can precisely control PEG hydrogel properties by adjusting the molecular weight of the polymer chains, the density of crosslinks between chains, and the incorporation of functional groups that provide specific capabilities. For example, PEG can be modified to include cell-adhesive peptides that promote beta cell attachment and survival, or it can be designed to degrade at controlled rates, allowing gradual integration with surrounding tissue.
Other synthetic polymers being explored include polycaprolactone (PCL), polylactic acid (PLA), and their copolymers. Poly (L-lactic-co-caprolactone) (PLCL), a co-polymer of PCL and polylactic acid (PLA), offers adjustable degradation and mechanical properties based on the PCL-to-PLA ratio. PLCL is also biocompatible, cost-effective, and holds significant potential for soft tissue engineering. These biodegradable polymers gradually break down in the body through hydrolysis or enzymatic degradation, potentially reducing long-term complications associated with permanent implants.
Hybrid Approaches: Combining the Best of Both Worlds
The combination of natural and synthetic hydrogels offers the opportunity to correct the defects of natural components while maintaining their beneficial properties. By blending natural and synthetic materials, researchers can create hybrid hydrogels that leverage the bioactivity and cell-recognition properties of natural materials while gaining the mechanical strength, reproducibility, and tunable properties of synthetic polymers.
For example, researchers have developed interpenetrating polymer networks where alginate and synthetic polymers form interwoven networks, each contributing distinct properties to the final material. Novel thermosensitive interpenetrating networks (IPN) of alginate and human adipose tissue-derived ECM were fabricated as a biomimetic encapsulate environment for islets delivery. For encapsulation, islets were added to an alginate solution, then the system was crosslinked through ionic gelation, and finally, the microencapsulated structure was added to the ECM-derived hydrogel. Such systems can provide both the immediate structural support of synthetic polymers and the long-term biological functionality of natural ECM components.
Nanomaterials: Precision at the Molecular Scale
While hydrogels operate at the microscale to macroscale, nanomaterials bring precision engineering to the molecular level, offering unique capabilities for enhancing beta cell survival and function. Nanomaterials are structures with at least one dimension measuring between 1 and 100 nanometers—roughly one-thousandth the width of a human hair. At this scale, materials exhibit unique physical, chemical, and biological properties that differ from their bulk counterparts.
Nanoencapsulation: Ultra-Thin Protective Coatings
Nanoencapsulation is a technique where thin films of a hydrogel are placed onto the surface of a cell aggregate, such as the pancreatic islet, by interfacial polymerization. The final cross-linked hydrogel film results in a nanometric conformal coating placed around the surface of each individual islet or cell aggregate. These ultra-thin coatings, typically measuring just tens to hundreds of nanometers in thickness, offer several advantages over thicker encapsulation systems.
The primary benefit of nanoencapsulation is improved mass transfer. Because the coating is so thin, glucose can reach the encapsulated cells more quickly, and insulin can exit more rapidly, enabling faster and more physiologically appropriate responses to changing blood glucose levels. Additionally, the minimal material volume means that more cells can be transplanted in a given space, potentially reducing the number of donor islets required for successful treatment.
However, nanoencapsulation also presents challenges. In some cases, islets are exposed because they are not completely coated, which can trigger the host’s immune reaction, resulting into graft failure. Ensuring complete, uniform coverage of irregularly shaped islets requires sophisticated fabrication techniques and careful quality control. Additionally, retrievability is an issue that needs to be addressed urgently with nanoencapsulation approaches, as the tiny capsules cannot be easily removed if problems arise.
Nanoparticles for Targeted Delivery
Beyond encapsulation, nanoparticles can serve as delivery vehicles for therapeutic agents that enhance beta cell survival and function. These nanocarriers can be loaded with growth factors, anti-inflammatory drugs, immunomodulatory molecules, or nutrients and designed to release their cargo in response to specific triggers such as changes in pH, temperature, or the presence of particular enzymes.
For instance, nanoparticles can be engineered to release anti-inflammatory agents in response to inflammatory signals, providing targeted protection precisely when and where it is needed. This responsive delivery can be more effective than continuous drug release while minimizing side effects by reducing overall drug exposure. Nanoparticles can also improve the stability and bioavailability of therapeutic molecules that would otherwise degrade quickly in the body.
Encapsulation Strategies: From Nano to Macro
Biomaterial-based beta cell encapsulation can be implemented at multiple scales, each offering distinct advantages and challenges. Two main approaches to beta cell therapies have been developed, namely macro-scale and micro-scale delivery systems. Understanding these different strategies is essential for appreciating the versatility and potential of biomaterial approaches.
Macroencapsulation: Retrievable Devices
Macroencapsulation involves placing large numbers of islets within a single, relatively large device that can be surgically implanted and, if necessary, retrieved. These devices typically consist of a semipermeable membrane that forms a chamber containing the therapeutic cells. The membrane allows small molecules like glucose, oxygen, and insulin to pass through while blocking immune cells and antibodies.
Macrodevices facilitate graft retrievability but limit oxygen supply. The ability to remove the device if complications arise is a significant safety advantage, particularly important for early-stage clinical trials. However, the large size of macrodevices creates challenges for oxygen and nutrient diffusion. Cells in the center of a large device may be too far from blood vessels to receive adequate oxygen, leading to cell death in the device core.
To address this limitation, researchers are developing macrodevices with optimized geometries that maximize surface area relative to volume, such as flat sheets or hollow fibers rather than spheres. Some designs incorporate oxygen-generating materials or prevascularization strategies to ensure adequate oxygen supply throughout the device. Clinical trials with various macroencapsulation devices are currently underway, with some showing promising early results in maintaining glucose control in diabetic patients.
Microencapsulation: Distributed Protection
Microencapsulation involves coating individual islets or small clusters of cells with a thin layer of biomaterial, typically creating spherical capsules ranging from 200 to 1000 micrometers in diameter. Microcapsules offer better nutrient support due to higher surface-to-volume ratios. Because each capsule is small, oxygen and nutrients can reach the encapsulated cells more easily, and insulin can exit more quickly, enabling better metabolic function.
Microencapsulation also offers the advantage of distributed risk—if some capsules fail, others may continue functioning, whereas failure of a single macrodevice means complete loss of all encapsulated cells. Additionally, microcapsules can be injected through minimally invasive procedures rather than requiring surgical implantation, potentially making the treatment more accessible and reducing patient burden.
The most common approach to microencapsulation uses alginate, which can be formed into uniform spherical beads through a process where alginate solution containing islets is dripped into a calcium chloride solution. The calcium ions crosslink the alginate, forming stable gel beads that encapsulate the cells. Researchers have refined this process over decades, optimizing parameters such as alginate purity, molecular weight, and capsule size to maximize cell survival and function while minimizing immune responses.
However, microencapsulation also presents challenges. The capsules cannot be easily retrieved if problems arise, and ensuring uniform quality across thousands or millions of individual capsules requires sophisticated manufacturing processes. Additionally, some microcapsules can trigger foreign body responses that lead to fibrosis—the formation of scar tissue around the capsules that impairs nutrient and oxygen diffusion.
Three-Dimensional Bioprinting: Precision Architecture
3D bioprinting fabricates structures with desired geometry while maintaining the porosity and spatial distribution of cells. Studies have shown that hydrogel-based 3D printed scaffolds support pancreatic islet viability and functionality by maintaining cell–cell interactions and promoting glucose responsive insulin secretion. This emerging technology allows researchers to precisely position cells and materials in three-dimensional space, creating complex architectures that mimic natural tissue organization.
In 3D bioprinting for beta cell therapy, cells are suspended in a bioink—a printable biomaterial formulation—and deposited layer by layer according to a computer-designed pattern. This approach enables the creation of structures with controlled porosity for optimal nutrient diffusion, defined channels for vascularization, and spatial organization that promotes cell-cell interactions important for proper islet function.
A 3D-printed microdevice encapsulates vascularized islets composed of iPSC-derived β-like cells and microvascular fragments for type 1 diabetes treatment. Such advanced approaches combine multiple strategies—stem cell-derived beta cells, prevascularization, and precision architecture—to create highly functional tissue constructs that may overcome many limitations of conventional encapsulation methods.
Addressing Critical Challenges: Oxygen, Vascularization, and Immune Modulation
While biomaterial encapsulation provides physical protection for beta cells, several critical challenges must be addressed to ensure long-term survival and function of encapsulated cells. Researchers are developing innovative strategies to tackle these obstacles, often incorporating multiple approaches within a single biomaterial system.
Overcoming Oxygen Limitations
Pancreatic beta cells are highly metabolically active and require substantial oxygen to function properly. Oxygen has an essential role in islet survival and function, improving oxygen permeability in encapsulation materials will be key to improve transplantation outcomes. In native pancreatic tissue, islets receive oxygen from a dense network of blood vessels, but encapsulated islets are initially isolated from the blood supply and must rely on oxygen diffusing through the biomaterial from surrounding tissues.
This diffusion-limited oxygen supply is particularly problematic immediately after transplantation, before new blood vessels can grow to the implant site—a process that can take weeks. During this critical period, many encapsulated cells die from hypoxia (oxygen deprivation), significantly reducing the effectiveness of the therapy.
To address this challenge, researchers have developed oxygen-generating biomaterials. The team developed a hydrolytically activated, oxygen-generating biomaterial using polydimethylsiloxane (PDMS) encapsulated solid calcium peroxide (CaO2). The encapsulation in PDMS restrained the rapid hydrolytic reactivity of CaO2, enabling a sustained oxygen release over 6 weeks at an average rate of 0.026 mM per day. This biomaterial was evaluated using a beta cell line (MIN6) and pancreatic rat islets, demonstrating that the PDMS-CaO2 disks could eliminate hypoxia-induced dysfunction and death, maintaining metabolic function and glucose-dependent insulin secretion at levels comparable to normoxic controls.
Oxygenating strategies, such as the use of oxygen-releasing biomaterials, are developed to improve oxygen diffusion and promote cell survival. These materials can provide a critical bridge, sustaining encapsulated cells during the vulnerable early post-transplantation period until vascularization is established. Other approaches include using highly oxygen-permeable materials, creating thin devices that minimize diffusion distances, or incorporating oxygen-carrying molecules like perfluorocarbons that can store and release oxygen.
Promoting Vascularization
While oxygen-generating materials provide temporary support, long-term success of beta cell transplantation requires the formation of new blood vessels (vascularization) that can provide sustained oxygen and nutrient supply. Promoting vascularization through the use of angiogenic growth factors and the incorporation of pre-vascularized materials are also explored to enhance nutrient and oxygen supply to the encapsulated cells.
Angiogenic growth factors such as vascular endothelial growth factor (VEGF) are proteins that stimulate the formation of new blood vessels. By incorporating these factors into biomaterial systems, researchers can actively recruit blood vessels to grow toward and around the encapsulated cells. The growth factors can be physically entrapped within the biomaterial matrix and released gradually, or they can be chemically tethered to the material to create sustained signaling.
An even more advanced approach involves prevascularization—creating blood vessel networks within the construct before transplantation. This can be achieved by co-encapsulating beta cells with endothelial cells (the cells that line blood vessels) and supporting cells that help stabilize vessel formation. When implanted, these pre-formed vessel networks can more quickly connect with the host’s circulatory system, dramatically reducing the hypoxic period and improving cell survival.
PLG’s dense pores are conducive to substance exchange and vascular reconstruction. The physical structure of biomaterials also influences vascularization. Materials with appropriate pore sizes and interconnected pore networks allow endothelial cells to migrate into the material and form vessel networks, while also permitting the diffusion of angiogenic signals and nutrients.
Immune Modulation and Anti-Inflammatory Strategies
While physical encapsulation provides a barrier against immune cells and antibodies, it cannot completely prevent immune-mediated damage. Current polymer hydrogel networks have been shown to block immune response cells and antibodies to protect islet cells, but permeation-selective barriers do not prevent low-molecular-weight cytotoxic molecules, such as interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) from diffusing into the capsule material and damaging islet cells. These small inflammatory molecules can pass through the biomaterial pores and trigger beta cell death.
To address this vulnerability, researchers are developing biomaterials with active immunomodulatory properties. A poly(ethylene glycol)-containing hydrogel network, formed by native chemical ligation and presenting an inhibitory peptide for islet cell surface IL-1 receptor, was able to maintain the viability of encapsulated islet cells in the presence of a combination of cytokines including IL-1β, TNF-α, and INF-γ. In stark contrast, cells encapsulated in unmodified hydrogels were mostly destroyed by cytokines which diffused into the capsules. At the same time, these peptide-modified hydrogels were able to efficiently protect encapsulated cells against β-cell specific T-lymphocytes and maintain glucose-stimulated insulin release by islet cells.
Biomaterials can be engineered to present potent immunomodulatory signals (FasL, PD-L1, anti-CD40L) or drugs (rapamycin) that can alter immune responses toward graft acceptance, thereby reducing reliance on systemic immunosuppression. These approaches work by locally modulating immune cell behavior rather than suppressing the entire immune system, potentially providing protection without the serious side effects of systemic immunosuppression.
FasL (Fas ligand), for example, can induce apoptosis in T cells that approach the encapsulated islets, creating a protective zone around the transplant. Co-transplantation of FasL protein overexpressed myoblasts with islets restored euglycemia without continuous immunosuppression. PD-L1 (programmed death-ligand 1) provides inhibitory signals to T cells, dampening their activation and preventing them from attacking the encapsulated cells. By presenting these molecules on biomaterial surfaces or incorporating them into the material matrix, researchers can create locally immunosuppressive microenvironments that protect transplanted cells without requiring systemic drugs.
Natural materials with inherent anti-inflammatory properties are also being explored. Tannic acid (TA) is a polyphenolic natural product and an effective antioxidant. By using TA, antioxidants and neutral polymer poly(n-vinylpyrrolidone) (PVPON) multilayers to form a nano-thin encapsulation material PVPON/TA. Such materials can neutralize reactive oxygen species and reduce inflammatory signaling, creating a more hospitable environment for encapsulated cells.
Preventing Foreign Body Response
Overcoming foreign body responses is a major focus of research. Strategies such as immunomodulatory materials and physical immunoshielding are investigated to reduce the immune response and improve the longevity of the encapsulated cells. The foreign body response is a natural reaction to implanted materials where the immune system attempts to isolate the foreign object by surrounding it with inflammatory cells and eventually encasing it in dense scar tissue (fibrosis).
This fibrotic capsule can severely impair the function of encapsulated beta cells by blocking the diffusion of glucose and oxygen to the cells and insulin from the cells. In severe cases, the fibrosis can completely strangle the encapsulated cells, causing them to die from lack of nutrients and oxygen.
Preventing foreign body response requires careful material selection and design. Materials that resist protein adsorption, such as PEG and zwitterionic polymers, are less likely to trigger strong foreign body responses. Surface modifications that present “self” signals or anti-inflammatory molecules can also reduce the intensity of the response. Additionally, the physical properties of materials—including their stiffness, surface topography, and degradation characteristics—influence how the immune system responds to them.
Enhancing Beta Cell Function: Beyond Protection
While protecting beta cells from immune attack and ensuring their survival are critical, biomaterials can also actively enhance the functional performance of encapsulated cells. Advanced biomaterial systems are being designed not just as passive barriers but as active participants in maintaining and improving beta cell health and insulin secretion.
Bioactive Molecules for Enhanced Function
Incorporating bioactive molecules into biomaterial systems can significantly improve the function of encapsulated beta cells. GLP-1 immobilized PEG hydrogels enhance the survival and insulin secretion of encapsulated islets. Overall, this study demonstrates a strategy to modify PEG hydrogels with bioactive peptide moieties that can significantly enhance the efficacy of islet encapsulation.
Glucagon-like peptide-1 (GLP-1) is a naturally occurring hormone that stimulates insulin secretion in response to glucose and also promotes beta cell survival and proliferation. By chemically attaching GLP-1 or similar molecules to hydrogel networks, researchers can create materials that continuously provide these beneficial signals to encapsulated cells. This approach can enhance both the quantity of insulin secreted and the sensitivity of the secretory response to glucose changes.
Other bioactive molecules being incorporated into biomaterials include growth factors that promote cell survival and proliferation, extracellular matrix proteins that provide cell-binding sites and structural cues, and small molecules that enhance cellular metabolism or protect against oxidative stress. In various studies, monoclonal antibodies, cytokines, chemokines, and growth factors are incorporated into the hydrogels to modulate the immune responses against the encapsulated islets and enhance the cell viability and biostability. On the other hand, the interaction of such biomolecules with hydrogel matrix, particularly growth factors, also improves their bioactivation and biostability over time.
Mimicking the Native Extracellular Matrix
The extracellular matrix surrounding beta cells in native pancreatic tissue provides crucial biochemical and mechanical signals that regulate cell behavior. Islets embedded in this hydrogel show increased glucose- and KCl-stimulated insulin secretion, and improved mitochondrial function compared to islets cultured without pancreatic matrix. By incorporating components of the native pancreatic ECM into biomaterial systems, researchers can create environments that better support beta cell function.
Decellularized pancreatic tissue—natural pancreatic tissue from which all cells have been removed, leaving only the ECM—can be processed into hydrogels that retain many of the biochemical signals of native tissue. Electrospinning hybrid scaffolds with silk fibroin (SF) and pig pancreatic decellularized ECM (P-dECM) were fabricated for β-cell encapsulation. To study the impact of ECM components on cell functionality, the viability and insulin secretion ability of cells were compared with non-encapsulated cells. Results showed that under high stimulation of glucose, the amount of insulin secretion from encapsulated cells was significantly higher than that from non-encapsulated ones.
These ECM-derived materials provide a complex mixture of proteins, glycoproteins, and proteoglycans that collectively create a biochemically rich environment. Cells can bind to these ECM components through specific receptors, triggering intracellular signaling pathways that promote survival, proper organization, and optimal function.
Mechanical Properties and Cell Behavior
As a biophysical feature of the environment, most of the cells can sense the mechanical nature of the surrounding environment and behave correspondingly. Therefore, tuning the mechanical properties of hydrogel could serve as a strategy to modulate encapsulated cell behaviors. The stiffness of the material surrounding cells influences their behavior through a process called mechanotransduction, where cells convert mechanical signals into biochemical responses.
Research has shown that beta cells function optimally when cultured in materials with stiffness similar to native pancreatic tissue—relatively soft compared to many other tissues. Materials that are too stiff can impair cell function and survival, while materials that are too soft may not provide adequate structural support. By carefully tuning the crosslinking density, polymer concentration, and composition of hydrogels, researchers can create materials with mechanical properties that optimize beta cell behavior.
Clinical Translation: From Laboratory to Patient
The ultimate goal of biomaterial research for beta cell therapy is to develop treatments that can be successfully applied in patients. Significant progress has been made in translating laboratory discoveries into clinical applications, with several approaches now being tested in human trials.
Current Clinical Trials and Results
Using more mature SC-β-cells, Vertex Pharmaceuticals initiated a phase 1/2 clinical trial (VX-880) in 2021, with cells transplanted intraportally into the liver under full-dose immunosuppression. By June 2024, 12 patients had been dosed; 11 of 12 had marked reduction or complete insulin independence, and all had HbA1c <7.0% and percentage of time spent with glucose in target range above 70%. These remarkable results demonstrate that stem cell-derived beta cells can effectively restore glucose control in patients with Type 1 diabetes.
However, the VX-880 approach still requires immunosuppression, highlighting the continued need for effective encapsulation strategies that can eliminate this requirement. In early 2025, it was announced that VX-264 did not meet the efficacy endpoint as a clinically relevant increase in C-peptide, indicative of endogenous insulin production, was not achieved. Consequently, VX-264 will not advance to next-phase trials. Meanwhile, Vertex intends to perform further investigations, including analyses of explanted devices, to elucidate the underlying factors contributing to these findings. This setback underscores the challenges of developing encapsulation devices that can maintain cell function long-term.
Recently, Sernova Corporation(London, ON, Canada) has successfully tested Cell Pouch technology that involves implantation of a SC-beta-cell-loaded cell pouch into T1D patients, enabling insulin secretion and regulation of blood glucose levels. Multiple companies and research institutions are pursuing various encapsulation strategies, each with unique designs and approaches to addressing the challenges of immune protection, vascularization, and long-term function.
Another clinical trial started in early 2025 aims to determine the therapeutic efficacy of autologous insulin-producing mesenchymal stem cell transplantation in youth with T1D (NCT06951074). This study aims to generate autologous insulin-producing mesenchymal stem cells derived from adipose tissue for transplant and evaluate the insulin-producing capacity of these cells both in vitro and in vivo. Using a patient’s own cells (autologous transplantation) could potentially reduce immune rejection, though challenges remain in efficiently converting these cells into functional beta cells.
Regulatory Considerations and Manufacturing Challenges
Translating biomaterial-based beta cell therapies from research to clinical practice requires navigating complex regulatory pathways and addressing significant manufacturing challenges. Regulatory agencies like the FDA and EMA require extensive evidence of safety and efficacy before approving new therapies, particularly those involving living cells and novel biomaterials.
Manufacturing cell-based therapies at clinical scale presents substantial challenges. Producing consistent, high-quality encapsulated cell products requires sophisticated facilities, rigorous quality control, and standardized processes. Each batch must meet strict specifications for cell viability, purity, potency, and sterility. For encapsulated products, additional parameters such as capsule size distribution, membrane integrity, and mechanical properties must be controlled.
The source of beta cells also presents regulatory and practical challenges. While donor islets from deceased organ donors have been used successfully, the severe shortage of donors limits this approach. Stem cell-derived beta cells offer a potentially unlimited supply, but ensuring their safety—particularly confirming that they won’t form tumors or differentiate into unwanted cell types—requires extensive testing and long-term monitoring.
Cost Considerations and Accessibility
The cost of developing and manufacturing advanced biomaterial-based cell therapies is substantial, raising important questions about accessibility and healthcare equity. Current cell therapies can cost hundreds of thousands of dollars per patient, placing them out of reach for many who could benefit. As these technologies mature and manufacturing processes are optimized, costs are expected to decrease, but ensuring broad access will require continued attention to affordability.
From a healthcare economics perspective, even expensive cell therapies may prove cost-effective if they can eliminate or substantially reduce the need for lifelong insulin therapy and prevent the serious complications of diabetes that require costly interventions. Comprehensive cost-effectiveness analyses will be important for informing coverage decisions and ensuring that these potentially transformative therapies reach the patients who need them.
Integration with Stem Cell Technology: Unlimited Cell Sources
One of the most exciting frontiers in beta cell therapy is the integration of advanced biomaterials with stem cell technology. Stem cell–derived β-cell therapy has emerged as a promising and potentially curative strategy for T1D by restoring endogenous insulin production through replacement of lost β-cell mass with functional insulin-secreting cells generated from human pluripotent stem cells, including hESCs and iPSCs.
Induced Pluripotent Stem Cells: Personalized Medicine
Induced pluripotent stem cells (iPSCs) are adult cells that have been reprogrammed to an embryonic-like state, giving them the ability to differentiate into any cell type in the body, including beta cells. We focus on the use of induced pluripotent stem cells as an alternative source for beta-cell generation, offering a solution to organ scarcity and providing a sustainable supply of insulin-producing cells. iPSCs can potentially be generated from a patient’s own cells, offering the possibility of personalized, immunologically matched cell therapy.
Recent advances in directed differentiation, gene-editing technologies, and optimized culture systems have significantly improved β-cell yield, functional maturity, and glucose responsiveness. In parallel, innovations in immune protection and graft survival—such as encapsulation biomaterials, oxygenation-enhancing scaffolds, and hypoimmunogenic engineered cell lines—have further strengthened the translational potential and durability of stem cell–derived β-cell replacement therapies.
Researchers have developed sophisticated protocols that guide stem cells through the stages of pancreatic development, mimicking the natural process by which beta cells form during embryonic development. These protocols involve exposing cells to specific combinations of growth factors and signaling molecules in carefully timed sequences, progressively directing them toward the beta cell fate. Recent refinements have produced stem cell-derived beta cells that closely resemble native beta cells in their gene expression patterns, insulin content, and glucose-responsive secretion.
Gene Editing for Immune Evasion
Gene editing (e.g., CRISPR-Cas9) is used to modify stem cells to make them less likely to be recognized and attacked by the immune system. Using the CRISPR-Cas9 system in human iPSCs, β2-microglobulin (B2M) and class II transactivator (CIITA) genes were deleted to remove human leukocyte antigen (HLA) class I and class II molecules, respectively, while PDL1, HLA-G, and CD47 were overexpressed to suppress T cells, modulate natural killer (NK) cells, and inhibit macrophages, respectively.
The gene-edited iPSCs demonstrated long-term survival in humanized mouse models without any immunosuppression. This approach of creating “hypoimmunogenic” or “stealth” cells that evade immune recognition could potentially eliminate the need for both immunosuppressive drugs and physical encapsulation, though combining gene editing with biomaterial encapsulation may provide even more robust protection.
Further, encapsulation technology and immune-modulating biomaterials can be used to enclose beta cells in biocompatible materials that allow insulin to pass through but shield the cells from immune system attacks. The combination of gene-edited cells and advanced biomaterials represents a powerful synergistic approach that leverages multiple mechanisms of immune protection.
Future Directions: Next-Generation Biomaterial Systems
As the field continues to advance, researchers are developing increasingly sophisticated biomaterial systems that integrate multiple functional capabilities into single platforms. These next-generation approaches promise to address remaining challenges and bring us closer to truly curative diabetes treatments.
Smart, Responsive Materials
These systems are engineered to release insulin in a controlled manner, guided by real-time blood glucose monitoring, thereby providing a customized approach to managing T1DM. For example, hydrogels that expand or contract in response to changes in glucose concentrations have been developed, enabling on-demand insulin release as required. While these glucose-responsive materials are primarily being developed for insulin delivery, similar concepts could be applied to encapsulation systems that adjust their properties in response to physiological conditions.
Future biomaterials might dynamically adjust their permeability in response to inflammatory signals, becoming more protective when immune activity increases. They could release therapeutic molecules only when specific triggers indicate they are needed, minimizing side effects while maximizing efficacy. Materials that can sense and respond to their environment represent a new paradigm in biomaterial design, moving from passive barriers to active, intelligent systems.
Multifunctional Integrated Systems
The most advanced biomaterial systems now being developed integrate multiple functional components into unified platforms. These might combine oxygen-generating materials with immunomodulatory molecules, prevascularization strategies, and ECM-mimicking structures, all within a single device or capsule. Such integrated approaches can address multiple challenges simultaneously, potentially achieving synergistic benefits that exceed the sum of individual components.
For example, a next-generation encapsulation system might include: a core of beta cells embedded in ECM-derived hydrogel for optimal function; a middle layer containing oxygen-generating materials and angiogenic factors; and an outer layer presenting immunomodulatory molecules and designed to resist fibrosis. Such multilayered, multifunctional systems represent the cutting edge of biomaterial design for cell therapy.
Personalized Biomaterial Approaches
As our understanding of individual variation in immune responses and tissue healing grows, there is increasing interest in personalizing biomaterial approaches to individual patients. This might involve selecting specific biomaterial compositions based on a patient’s immune profile, adjusting material properties to match individual tissue characteristics, or combining autologous cells with customized encapsulation systems.
Advanced manufacturing technologies like 3D bioprinting enable the creation of patient-specific devices with geometries optimized for particular implantation sites or designed to match individual anatomical features. As these technologies mature and become more accessible, personalized biomaterial therapies may become increasingly feasible.
Combination with Other Emerging Technologies
The future of beta cell therapy likely lies in combining biomaterial encapsulation with other emerging technologies. Integration with continuous glucose monitoring systems could enable real-time assessment of encapsulated cell function and early detection of problems. Combination with immunomodulatory drugs or cell therapies that specifically target the autoimmune processes underlying Type 1 diabetes could provide more comprehensive treatment.
Artificial intelligence and machine learning are being applied to optimize biomaterial design, predict immune responses, and personalize treatment approaches. These computational tools can analyze vast amounts of data from previous experiments and clinical trials to identify patterns and principles that guide the development of more effective systems.
Broader Applications Beyond Diabetes
While this article has focused on beta cell therapy for diabetes, the biomaterial strategies being developed have much broader potential applications. The principles of cell encapsulation, immune protection, and functional enhancement apply to many other cell-based therapies being developed for various diseases.
Encapsulation approaches similar to those used for beta cells are being explored for delivering therapeutic cells to treat liver disease, kidney failure, neurological disorders, and other conditions. The immunomodulatory biomaterials developed for protecting beta cells could be applied to organ transplantation, potentially reducing or eliminating the need for immunosuppressive drugs. Oxygen-generating materials and vascularization strategies have applications in tissue engineering for creating larger, more complex tissue constructs.
The lessons learned from decades of research on beta cell encapsulation are informing the broader field of regenerative medicine and providing a foundation for developing cell-based therapies for numerous diseases. As these technologies continue to mature, they promise to transform treatment options across many areas of medicine.
Challenges and Limitations
Despite remarkable progress, significant challenges remain before biomaterial-based beta cell therapies can achieve their full potential and become widely available treatments. Despite promising outcomes, several studies aiming to achieve insulin independence following islet/beta-cell transplantation, have reported low retention rates, limited cell survival, and hampered therapeutic potential. Designing biomaterial delivery vehicles is essential for improving the therapeuticefficacy after transplantation.
Long-term durability remains a critical concern. While some encapsulated cell systems have functioned for months or even years in animal models and early clinical trials, achieving truly lifelong function comparable to native beta cells remains elusive. Understanding and addressing the factors that limit long-term survival and function—including gradual loss of cells, declining insulin secretion, and progressive fibrosis—requires continued research.
Scalability and manufacturing consistency present practical challenges for clinical translation. Producing sufficient quantities of high-quality encapsulated cells to treat large numbers of patients requires sophisticated manufacturing capabilities and rigorous quality control. Ensuring batch-to-batch consistency while maintaining cell viability and function throughout the manufacturing process demands continued process optimization.
The optimal transplantation site for encapsulated beta cells remains debated. Selecting more appropriate graft sites, addressing blood and oxygen supply for long-term islet survival, and mitigating graft rejection are equally critical. The pancreas, being the physiological site of pancreatic islets, is undoubtedly a crucial consideration for transplantation, but surprisingly few studies have tested islet transplantation in situ. Different sites offer various advantages and disadvantages regarding accessibility, vascularization potential, oxygen availability, and retrievability.
Regulatory pathways for combination products involving both cells and biomaterials are complex and still evolving. Clear guidance on safety testing, efficacy endpoints, and long-term monitoring requirements will be important for facilitating clinical development while ensuring patient safety.
Conclusion: A Promising Future
The development of a bioartificial pancreas has emerged as a promising concept for the treatment of insulin-deficient patients, offering a potential solution to overcome the limitations of current treatments. The field of biomaterial-based beta cell therapy has made remarkable strides over the past decades, evolving from simple alginate capsules to sophisticated, multifunctional systems that integrate multiple strategies for protecting and enhancing cell function.
These materials have the potential to address the challenges associated especially with islet transplantation, such as immune rejection and graft failure, and improve clinical outcomes for patients with type 1 diabetes. Current clinical trials are demonstrating that stem cell-derived beta cells can effectively restore glucose control in diabetic patients, and ongoing research is addressing the remaining challenges of immune protection, long-term durability, and scalability.
The integration of biomaterials with stem cell technology, gene editing, 3D bioprinting, and other emerging technologies is creating powerful synergies that promise to overcome current limitations. Recent advancements in graft survival and immune protection have facilitated the clinical translation of stem cell–derived β-cell products, which are now progressing from preclinical studies into early-phase human trials distinct from conventional donor islet transplantation already practiced in several countries. Innovations such as new biomaterials, oxygenation-enhancing scaffolds, gene-edited hypoimmunogenic cell lines, and co-transplantation strategies are effectively addressing immune rejection and enhancing engraftment.
Many of these strategies are progressing toward pivotal studies in large animals and first-in-human studies. As these approaches advance through clinical development, they bring us closer to the goal of providing diabetes patients with a functional cure—a treatment that can restore natural insulin production, eliminate the need for exogenous insulin and immunosuppression, and prevent the devastating complications of diabetes.
While challenges remain, the trajectory of progress is clear and encouraging. The convergence of advances in biomaterials science, stem cell biology, immunology, and bioengineering is creating unprecedented opportunities to transform diabetes treatment. For the millions of people living with diabetes worldwide, these innovations offer hope for a future where the disease can be truly cured rather than merely managed, restoring quality of life and eliminating the burden of lifelong treatment and complications.
The journey from laboratory discovery to clinical reality is long and challenging, but the remarkable progress achieved thus far demonstrates that the goal is achievable. Continued investment in research, collaboration across disciplines, and commitment to translating discoveries into accessible treatments will be essential for realizing the full potential of biomaterial-based beta cell therapies. As we look to the future, there is genuine reason for optimism that these innovative approaches will fundamentally change the lives of people with diabetes.
Additional Resources and Further Reading
For those interested in learning more about biomaterials for beta cell therapy and diabetes treatment, several excellent resources are available. The American Diabetes Association provides comprehensive information about diabetes research and treatment advances. The JDRF (Juvenile Diabetes Research Foundation) funds cutting-edge research on Type 1 diabetes cures and maintains updated information on clinical trials and emerging therapies.
Academic journals such as Diabetes, Cell Stem Cell, Biomaterials, and Advanced Healthcare Materials regularly publish the latest research findings in this field. ClinicalTrials.gov provides information about ongoing clinical trials of cell-based diabetes therapies, allowing patients and families to learn about opportunities to participate in research studies.
Professional organizations such as the Tissue Engineering and Regenerative Medicine International Society (TERMIS) and the Society for Biomaterials host conferences and publish resources on the latest advances in biomaterials and cell therapy. These organizations provide forums for researchers, clinicians, and industry professionals to share knowledge and collaborate on advancing the field.
As research continues to accelerate and new discoveries emerge, staying informed about the latest developments will help patients, families, and healthcare providers make informed decisions about treatment options and participate in the exciting progress toward a cure for diabetes.