Regulation of the Distribution of Cells in Mixed Spheroids by Altering Migration Direction

Scaffold-free endocrine tissue engineering: role of islet organization and implications in type 1 diabetes

Type 1 diabetes (T1D) is a chronic hyperglycemia disorder emerging from beta-cell (insulin secreting cells of the pancreas) targeted autoimmunity. As the blood glucose levels significantly increase and the insulin secretion is gradually lost, the entire body suffers from the complications. Although various advances in the insulin analogs, blood glucose monitoring and insulin application practices have been achieved in the last few decades, a cure for the disease is not obtained. Alternatively, pancreas/islet transplantation is an attractive therapeutic approach based on the patient prognosis, yet this treatment is also limited mainly by donor shortage, life-long use of immunosuppressive drugs and risk of disease transmission. In research and clinics, such drawbacks are addressed by the endocrine tissue engineering of the pancreas. One arm of this engineering is scaffold-free models which often utilize highly developed cell-cell junctions, soluble factors and 3D arrangement of islets with the cellular heterogeneity to prepare the transplant formulations. In this review, taking T1D as a model autoimmune disease, techniques to produce so-called pseudoislets and their applications are studied in detail with the aim of understanding the role of mimicry and pointing out the promising efforts which can be translated from benchside to bedside to achieve exogenous insulin-free patient treatment. Likewise, these developments in the pseudoislet formation are tools for the research to elucidate underlying mechanisms in pancreas (patho)biology, as platforms to screen drugs and to introduce immunoisolation barrier-based hybrid strategies.

The cultivation conditions affect the aggregation and functionality of β-cell lines alone and in coculture with mesenchymal stromal/stem cells

The manufacturing of viable and functional β-cell spheroids is required for diabetes cell therapy and drug testing. Mesenchymal stromal/stem cells (MSCs) are known to improve β-cell viability and functionality. We therefore investigated the aggregation behavior of three different β-cell lines (rat insulinoma-1 cell line [INS-1], mouse insulinoma-6 cell line [MIN6], and a cell line formed by the electrofusion of primary human pancreatic islets and PANC-1 cells [1.1B4]), two MSC types, and mixtures of β-cells and MSCs under different conditions. We screened several static systems to produce uniform β-cell and MSC spheroids, finding cell-repellent plates the most suitable. The three different β-cell lines differed in their aggregation behavior, spheroid size, and growth in the same static environment. We found no major differences in spheroid formation between primary MSCs and an immortalized MSC line, although both differed with regard to the aggregation behavior of the β-cell lines. All spheroids showed a reduced viability due to mass transfer limitations under static conditions. We therefore investigated three dynamic systems (shaking multi-well plates, spinner flasks, and shaking flasks). In shaking flasks, there were no β-cell-line-dependent differences in aggregation behavior, resulting in uniform and highly viable spheroids. We found that the aggregation behavior of the β-cell lines changed in a static coculture with MSCs. The β-cell/MSC coculture conditions must be refined to avoid a rapid segregation into distinct populations under dynamic conditions.

TLR3 and TLR7 RNA Sensor Activation during SARS-CoV-2 Infection

(1) Background: Acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological agent for the coronavirus disease (COVID-19) that has led to a pandemic that began in March 2020. The role of the SARS-CoV-2 components on innate and adaptive immunity is still unknown. We investigated the possible implication of pathogen-associated molecular patterns (PAMPs)-pattern recognition receptors (PRRs) interaction. (2) Methods: We infected Calu-3/MRC-5 multicellular spheroids (MTCSs) with a SARS-CoV-2 clinical strain and evaluated the activation of RNA sensors, transcription factors, and cytokines/interferons (IFN) secretion, by quantitative real-time PCR, immunofluorescence, and ELISA. (3) Results: Our results showed that the SARS-CoV-2 infection of Calu-3/MRC-5 multicellular spheroids induced the activation of the TLR3 and TLR7 RNA sensor pathways. In particular, TLR3 might act via IRF3, producing interleukin (IL)-1α, IL-1β, IL-4, IL-6, and IFN-α and IFN-β, during the first 24 h post-infection. Then, TLR3 activates the NFκB transduction pathway, leading to pro-inflammatory cytokine secretion. Conversely, TLR7 seems to mainly act via NFκB, inducing type 1 IFN, IFN-γ, and IFN-λ3, starting from the 48 h post-infection. (4) Conclusion: We showed that both TLR3 and TLR7 are involved in the control of innate immunity during lung SARS-CoV-2 infection. The activation of TLRs induced pro-inflammatory cytokines, such as IL-1α, IL-1β, IL-4, and IL-6, as well as interferons. TLRs could be a potential target in controlling the infection in the early stages of the disease.

Development of Advanced Cell-Based Therapy by Regulating Cell-Cell Interactions

Cell-based therapy for disease treatment involves the transplantation of cells obtained either from self or others into relevant patients. While cells constituting the body tissues maintain homeostasis by performing remarkable functions through complicated cell-cell interactions, transplanted cells, which are generally cultured as a monolayer, are unable to recapitulate similar interactions in vivo. The regulation of cell-cell interactions can immensely increase the function and therapeutic effect of transplanted cells. This review aims to summarize the methods of regulating cell-cell interactions that could significantly increase the therapeutic effects of transplanted cells. The first method involves the generation of multicellular spheroids by three-dimensional cell culture. Spheroid formation greatly improved the survival and therapeutic effects of insulin-secreting cells in diabetic mice after transplantation. Moreover, mixed multicellular spheroids, composed of insulin-secreting cells and aorta endothelial cells or fibroblasts, were found to significantly improve insulin secretion. Secondly, adhesamine derivatives, which are low-molecular-weight compounds that accelerate cell adhesion and avoid anoikis and anchorage-dependent apoptosis, have been used to improve the survival of bone marrow-derived cells and significantly enhanced the therapeutic effects in a diabetic mouse model of delayed wound healing. Finally, the avidin-biotin complex method, a cell surface modification method, has been applied to endow tumor-homing mesenchymal stem cells with anti-tumor ability by modifying them with doxorubicin-encapsulated liposomes. The modified cells showed excellent effectiveness in cell-based cancer-targeting therapy. The discussed methods can be useful tools for advanced cell-based therapy, promising future clinical applications.

Development of DNA-anchored assembly of small extracellular vesicle for efficient antigen delivery to antigen presenting cells

Tumor-cell derived small extracellular vesicle (sEV) combined with immunostimulatory adjuvants may serve as a promising tumor vaccine through the induction of the cytotoxic T cell response. To achieve an efficient immune response, the prolonged tissue residence after intradermal injection followed by the sustained and efficient delivery of tumor-cell derived sEV combined with adjuvants to antigen-presenting cells (APCs) is a promising strategy. In the present study, we constructed a DNA-anchored sEV superstructure in which tumor-cell derived sEVs were assembled with each other to achieve prolonged tissue residence and the ability to encourage selective uptake by dendritic cells. We prepared sEVs modified with immunostimulatory CpG-DNA containing an additional "sticky end" (CpG-sEV). CpG-sEVs were mixed with an oligonucleotide duplex containing the sequence complementary to the "sticky end" of the CpG-DNA, resulting in the self-assembly of CpG-sEV into a micrometer-sized superstructure. The CpG-DNA anchored sEV assembly (CpG-sEV assembly) was selectively taken up by APCs, compared to tumor cells or fibroblast cells, and it efficiently activated dendritic cells in vitro. Moreover, CpG-sEV assembly formation significantly prolonged tissue residence and increased the immune responses of immunostimulatory CpG-DNA intradermally injected into mice. These results indicate that CpG-sEV assembly is an effective system which may be useful for tumor immunotherapy.