Islet encapsulated implantable composite hollow fiber membrane based device: A bioartificial pancreas

Immune isolation-enabled nanoencapsulation of donor T cells: a promising strategy for mitigating GVHD and treating AML in preclinical models

BACKGROUND

In allogeneic-hematopoietic stem cell transplantation for acute myeloid leukemia (AML), donor T cells combat leukemia through the graft-versus-leukemia (GVL) effect, while they also pose a risk of triggering life-threatening graft-versus-host disease (GVHD) by interacting with recipient cells. The onset of GVHD hinges on the interplay between donor T cells and recipient antigen-presenting cells (APCs), sparking T-cell activation. However, effective methods to balance GVHD and GVL are lacking.

METHODS

In our study, we crafted nanocapsules by layering polycationic aminated gelatin and polyanionic alginate onto the surface of T cells, examining potential alterations in their fundamental physiological functions. Subsequently, we established an AML mouse model and treated it with transplantation of bone marrow cells (BMCs) combined with encapsulated T cells to investigate the GVL and anti-GVHD effects of encapsulated T cells. In vitro co-culture was employed to probe the effects of encapsulation on immune synapses, co-stimulatory molecules, and tumor-killing pathways.

RESULTS

Transplantation of BMCs combined with donor T cells selectively encapsulated onto AML mice significantly alleviates GVHD symptoms while preserving essential GVL effects. Encapsulated T cells exerted their immunomodulatory effects by impeding the formation of immune synapses with recipient APCs, thereby downregulating co-stimulatory signals such as CD28-CD80, ICOS-ICOSL, and CD40L-CD40. Recipient mice receiving encapsulated T-cell transplantation exhibited a marked increase in donor Ly-5.1-BMC cell numbers, accompanied by unaltered in vivo expression levels of perforin and granzyme B. While transient inhibition of donor T-cell cytotoxicity in the tumor microenvironment was observed in vitro following single-cell nanoencapsulation, subsequent restoration to normal antitumor activity ensued, attributed to selective permeability of encapsulated vesicle shells and material degradation. Moreover, the expression of apoptotic proteins and FAS-FAS ligand pathway at normal levels was still observed in leukemia tumor cells.

CONCLUSIONS

Encapsulated donor T cells effectively mitigate GVHD while preserving the GVL effect by minimizing co-stimulatory signaling with APCs through early immune isolation. Subsequent degradation of nanocapsules restores T-cell cytotoxic efficacy against AML cells, mediated by cytotoxic pathways. Using transplant-encapsulated T cells offers a promising strategy to suppress GVHD while preserving the GVL effect.

Encapsulation and immune protection for type 1 diabetes cell therapy

Type 1 Diabetes (T1D) involves the autoimmune destruction of insulin-producing β-cells in the pancreas. Exogenous insulin injections are the current therapy but are user-dependent and cannot fully recapitulate physiological insulin secretion dynamics. Since the emergence of allogeneic cell therapy for T1D, the Edmonton Protocol has been the most promising immunosuppression protocol for cadaveric islet transplantation, but the lack of donor islets, poor cell engraftment, and required chronic immunosuppression have limited its application as a therapy for T1D. Encapsulation in biomaterials on the nano-, micro-, and macro-scale offers the potential to integrate islets with the host and protect them from immune responses. This method can be applied to different cell types, including cadaveric, porcine, and stem cell-derived islets, mitigating the issue of a lack of donor cells. This review covers progress in the efforts to integrate insulin-producing cells from multiple sources to T1D patients as a form of cell therapy.

Immunoengineering Biomaterials in Cell-Based Therapy for Type 1 Diabetes

Type 1 diabetes (T1D) is caused by low insulin production and chronic hyperglycemia due to the destruction of pancreatic β-cells. Cell transplantation is an attractive alternative approach compared to insulin injection. However, cell therapy has been limited by major challenges including life-long requirements for immunosuppressive drugs in order to prevent host immune responses. Encapsulation of the transplanted cells can solve the problem of immune rejection, by providing a physical barrier between the transplanted cells and the recipient's immune cells. Despite current disputes in cell encapsulation approaches, thanks to recent advances in the fields of biomaterials and transplantation immunology, extensive effort has been dedicated to immunoengineering strategies in combination with encapsulation technologies to overcome the problem of the host's immune responses. The current review summarizes the most commonly used encapsulation and immunoengineering strategies combined with cell therapy which has been applied as a novel approach to improve cell replacement therapies for the management of T1D. Recent advances in the fields of biomaterial design, nanotechnology, as well as deeper knowledge about immune modulation had significantly improved cell encapsulation strategies. However, further progress requires the combined application of novel immunoengineering approaches and islet/ß-cell transplantation.

Mesenchymal Stem Cell-Based Therapy for Diabetes Mellitus: Enhancement Strategies and Future Perspectives

Diabetes mellitus (DM), a chronic disorder of carbohydrate metabolism, is characterized by the unbridled hyperglycemia resulted from the impaired ability of the body to either produce or respond to insulin. As a cell-based regenerative therapy, mesenchymal stem cells (MSCs) hold immense potency for curing DM duo to their easy isolation, multi-differentiation potential, and immunomodulatory property. However, despite the promising efficacy in pre-clinical animal models, naive MSC administration fails to exhibit clinically satisfactory therapeutic outcomes, which varies greatly among individuals with DM. Recently, numbers of innovative strategies have been applied to improve MSC-based therapy. Preconditioning, genetic modification, combination therapy and exosome application are representative strategies to maximize the therapeutic benefits of MSCs. Therefore, in this review, we summarize recent advancements in mechanistic studies of MSCs-based treatment for DM, and mainly focus on the novel approaches aiming to improve the anti-diabetic potentials of naive MSCs. Additionally, the potential directions of MSCs-based therapy for DM are also proposed at a glance.

Electrospun freestanding hydrophobic fabric as a potential polymer semi-permeable membrane for islet encapsulation

One of the significant problems associated with islet encapsulation for type 1 diabetes treatment is the loss of islet functionality or cell death after transplantation because of the unfavorable environment for the cells. In this work, we propose a simple strategy to fabricate electrospun membranes that will provide a favorable environment for proper islet function and also a desirable pore size to cease cellular infiltration, protecting the encapsulated islet from immune cells. By electrospinning the wettability of three different biocompatible polymers: cellulose acetate (CA), polyethersulfone (PES), and polytetrafluoroethylene (PTFE) was greatly modified. The contact angle of electrospun CA, PES, and PTFE increased to 136°, 126°, and 155° as compared to 55°, 71°, and 128° respectively as a thin film, making the electrospun membranes hydrophobic. Commercial porous membranes of PES and PTFE show a contact angle of 30° and 118°, respectively, confirming the hydrophobicity of electrospun membranes is due to the surface morphology induced by electrospinning. In- vivo results confirm that the induced hydrophobicity and surface morphology of electrospun membranes impede cell attachment, which would help in maintaining the 3D circular morphology of islet cell. More importantly, the pore size of 0.3-0.6 μm obtained due to the densely packed structure of nanofibers, will be able to restrict immune cells but would allow free movement of molecules like insulin and glucose. Therefore, electrospun polymer fibrous membranes as fabricated in this work, with hydrophobic and porous properties, make a strong case for successful islet encapsulation.

Paving the way for successful islet encapsulation

Type 1 diabetes mellitus (T1DM) is a disorder that decimates pancreatic β-cells which produce insulin. Direct pancreatic islet transplantation cannot serve as a widespread therapeutic modality owing to the need for lifelong immunosuppression and donor shortage. Therefore, several encapsulation techniques have been developed to enclose the islets in semipermeable vehicles that will allow oxygen and nutrient input as well as insulin, other metabolites and waste output, while accomplishing immunoisolation. Although encapsulation technology continues to face significant obstacles, recent advances in material science, stem cell biology and immunology potentially serve as pathways to success. This review summarizes the accomplishments of the past 5 years.

Feasibility of Induced Pluripotent Stem Cell Therapies for Treatment of Type 1 Diabetes

IMPACT STATEMENT

This review of iPSCs to treat T1D provides a current assessment of the challenges and potential for this proposed new therapy.

Lactobionic acid-functionalized polyethersulfone hollow fiber membranes promote HepG2 attachment and function

Surface modification of polyethersulfone hollow fibers, which are important in bio-artificial liver, is increasingly used to improve biocompatibility and promote the adhesion and proliferation of hepatocytes resulting in improved cell functionality. Hepatocytes are anchorage-dependent cells, and membrane surface modification enhances the hepatic cell adhesion and proliferation. Specific interaction of the asialoglycoprotein receptor on hepatocyte cell surfaces with a galactose moiety enhances the attachment of the cells on a biocompatible substrate. In this study, the outer surface of the polyethersulfone (P) hollow fiber membranes (HFMs) was chemically modified by covalent coupling with lactobionic acid (LBA). The energy dispersive X-ray spectrometry elemental mapping, attenuated total reflectance-Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy confirmed the LBA-coupling on the outer surface of P-LBA HFMs. Hemocompatibility study indicated the suitability of the modified membranes with human blood. These membranes showed remarkably improved biocompatibility with human primary mesenchymal stem cells and HepG2 cells. Characteristic multi-cellular spheroids of HepG2 cells were observed under scanning electron and confocal microscopy. HepG2 cell functional activity was measured by quantifying the urea synthesis, albumin secretion and glucose consumption in the culture media, which indicated the improved HepG2 functions. These experimental results clearly suggest the potentiality of these LBA-modified P HFMs as a suitable biocompatible substrate for promoting HepG2 attachment and function leading to their application in bioreactors and bio-artificial liver devices.

Surface modification of polyethersulfone hollow fibers, which are important in bio-artificial liver, is increasingly used to improve biocompatibility and promote the adhesion and proliferation of hepatocytes resulting in improved cell functionality.

Cell derived extracellular matrix fibers synthesized using sacrificial hollow fiber membranes

The therapeutic potential of biological scaffolds as adjuncts to synthetic polymers motivates the engineering of fibers formed using the extracellular matrix (ECM) secreted by cells. To capture the ECM secreted by cells during in vitro culture, a solvent degradable hollow fiber membrane (HFM) was created and utilized as a cell culture platform. NIH/3T3 fibroblasts were injected into the narrow (0.986 ± 0.042 mm) lumina of mesoporous polysulfone HFMs and maintained in culture for up to 3 weeks. Following cell culture, HFMs were dissolved using N-methyl-2-pyrrolidone and the accumulated ECM was collected. The ECM retained the filamentous dimensions of the HFM lumen. The process yielded up to 0.89 ± 0.20 mg of ECM for every mm of HFM dissolved. Immunofluorescence, second-harmonic generation microscopy, and tandem mass spectrometry indicated the presence of an array of ECM constituents, including collagen, fibronectin, and proteoglycans, while FTIR spectra suggested thorough HFM material dissolution. Isolated ECM fibers, although fragile, were amenable to handling and exhibited an average elastic modulus of 34.6 ± 15.3 kPa, ultimate tensile strength of 5.2 ± 2.2 kPa, and elongation-at-break of 29% ± 18%. ECM fibers consisted of an interconnected yet porous (32.7% ± 5.8% open space) network which supported the attachment and in vitro proliferation of mammalian cells. ECM fibers were similarly synthesized using muscle and astrocyte cells, suggesting process robustness across different cell types. Ultimately, these ECM fibers could be utilized as an alternative to synthetics for the manufacture of woven meshes targeting wound healing or regenerative medicine applications.