Long-Jun Dai

Different effects of FK506, rapamycin, and mycophenolate mofetil on glucose-stimulated insulin release and apoptosis in human islets.

Pancreatic islet transplantation has the potential to be an effective treatment for type 1 diabetes mellitus. While recent improvements have improved 1-year outcomes, follow-up studies show a persistent loss of graft function/survival over 5 years. One possible cause of islet transplant failure is the immunosuppressant regimen required to prevent alloimmune graft rejection. Although there is evidence from separate studies, mostly in rodents and cell lines, that FK506 (tacrolimus), rapamycin (sirolimus), and mycophenolate mofetil (MMF; CellCept) can damage pancreatic β-cells, there have been few side-by-side, multiparameter comparisons of the effects of these drugs on human islets. In the present study, we show that 24-h exposure to FK506 or MMF impairs glucose-stimulated insulin secretion in human islets. FK506 had acute and direct effects on insulin exocytosis, whereas MMF did not. FK506, but not MMF, impaired human islet graft function in diabetic NOD.scid mice. All of the immunosuppressants tested in vitro increased caspase-3 cleavage and caspase-3 activity, whereas MMF induced ER-stress to the greatest degree. Treating human islets with the GLP-1 agonist exenatide ameliorated the immunosuppressant-induced defects in glucose-stimulated insulin release. Together, our results demonstrate that immunosuppressants impair human β-cell function and survival, and that these defects can be circumvented to a certain extent with exenatide treatment.

Potential implications of mesenchymal stem cells in cancer therapy

Mesenchymal stem cells (MSCs) are the first type of stem cells to be utilized in clinical regenerative medicine, mainly owing to their capacity for multipotent differentiation and the feasibility of autologous transplantation. More recently, the specific tumor-oriented migration and incorporation of MSCs have been demonstrated in various pre-clinical models, highlighting the potential for MSCs to be used as an ideal carrier for anticancer gene delivery. Engineered with specific anticancer genes, MSCs possess the ability of dual-targeting tumor cells. This contrasts with non-engineered native MSCs which have intrinsic pro- and anti-tumorigenic properties. Engineered MSCs are capable of producing specific anticancer agents locally and constantly. Astute investigation on engineered MSCs may lead to a new avenue toward an efficient therapy for patients with cancer.

Dynamic assessment of cell viability, proliferation and migration using real time cell analyzer system (RTCA)

Cell viability and cell migration capacities are critical parameters for cell culture-related studies. It is essential to monitor the dynamic changes of cell properties under various co-culture conditions to our better understanding of their behaviours and characteristics. The real time cell analyzer (RTCA, xCELLigence, Roche) is an impedance-based technology that can be used for label-free and real-time monitoring of cell properties, such as cell adherence, proliferation, migration and cytotoxicity. The practicality of this system has been proven in our recent cancer studies. In the present method, we intend to use co-cultures of pancreatic cancer cells (HP62) and mesenchymal stem cells to describe in detail, the procedures and benefits of RTCA.

Therapeutic potential of CAR-T cell-derived exosomes: a cell-free modality for targeted cancer therapy

Chimeric antigen receptor (CAR)-based T-cell adoptive immunotherapy is a distinctively promising therapy for cancer. The engineering of CARs into T cells provides T cells with tumor-targeting capabilities and intensifies their cytotoxic activity through stimulated cell expansion and enhanced cytokine production. As a novel and potent therapeutic modality, there exists some uncontrollable processes which are the potential sources of adverse events. As an extension of this impactful modality, CAR-T cell-derived exosomes may substitute CAR-T cells to act as ultimate attackers, thereby overcoming some limitations. Exosomes retain most characteristics of parent cells and play an essential role in intercellular communications via transmitting their cargo to recipient cells. The application of CAR-T cell-derived exosomes will make this cell-based therapy more clinically controllable as it also provides a cell-free platform to diversify anticancer mediators, which responds effectively to the complexity and volatility of cancer. It is believed that the appropriate application of both cellular and exosomal platforms will make this effective treatment more practicable.

Do immunotherapy and ß cell replacement play a synergistic role in the treatment of type 1 diabetes

Type 1 diabetes (T1D) is the result of the autoimmune response against pancreatic insulin-producing ss-cells. Its ultimate consequence is beta-cell insufficiency-mediated dysregulation of blood glucose control. In terms of T1D treatment, immunotherapy addresses the cause of T1D, mainly through re-setting the balance between autoimmunity and regulatory mechanisms. Regulatory T cells play an important role in this immune intervention. An alternative T1D treatment is beta-cell replacement, which can reverse the consequence of the disease by replacing destroyed beta-cells in the diabetic pancreas. The applicable insulin-producing cells can be directly obtained from islet transplantation or generated from other cell sources such as autologous adult stem cells, embryonic stem cells, and induced pluripotent stem cells. In this review, we summarize the recent research progress and analyze the possible advantages and disadvantages of these two therapeutic options especially focusing on the potential synergistic effect on T1D treatment. Exploring the optimal combination of immunotherapy and beta-cell replacement will pave the way to the most effective cure for this devastating disease.

Cancer cell-oriented migration of mesenchymal stem cells engineered with an anticancer gene ( PTEN ): an imaging demonstration

Background Mesenchymal stem cells (MSCs) have been considered to hold great potential as ideal carriers for the delivery of anticancer agents since the discovery of their tumor tropism. This study was performed to demonstrate the effects of phosphatase and tensin homolog (PTEN) engineering on MSCs’ capacity for cancer cell-oriented migration. Methods MSCs were engineered with a PTEN-bearing plasmid and the expression was confirmed with Western blotting. A human glioma cell line (DBTRG) was used as the target cell; DBTRG cell-oriented migration of MSCs was monitored with a micro speed photographic system. Results The expression of transfected PTEN in MSCs was identified by immunoblotting analysis and confirmed with cell viability assessment of target cells. The DBTRG cell-oriented migration of PTEN-engineered MSCs was demonstrated by a real-time dynamic monitoring system, and a phagocytosis-like action of MSCs was also observed. Conclusion MSCs maintained their capacity for cancer cell-directed migration after they were engineered with anticancer genes. This study provides the first direct evidence of MSCs’ tropism post-anticancer gene engineering.

Mesenchymal Stem Cells: Prospects for Cancer Therapy

Cancer remains one of the leading causes of mortality and morbidity throughout the world. To a significant extent, current conventional cancer therapies are symptomatic and passive in nature. The major obstacle for the development of effective cancer therapy is believed to be the lack of sufficient specificity. Since the discovery of tumor-oriented homing capacity of mesenchymal stem cells (MSCs), the application of specific anticancer gene-engineered MSCs has held great potential for cancer therapies. The MSC-based multiple-targeted anticancer strategy is based on MSCs’ capacity of tumor-directed migration and incorporation and in situ expression of tumor-specific anticancer genes. Aimed at translating the benchwork to meaningful clinical applications, we will describe MSCs’ tumor tropism and their use as therapeutic vehicles, the multiple-targeted anticancer potential of engineered MSCs and a personalized strategy for cancer therapy.

Expression and tumor-promoting effects of caprin-1 in human glioma

Background: Cytoplasmic activation/proliferation-associated protein-1 (caprin-1) is a newly discovered RNA-binding protein and is now recognized as one of the putative oncogenes. This study was performed to reveal its presence in human gliomas and its oncogenic functions in human glioblastoma-derived Denver brain tumor research group 05 (DBTRG-05MG) cells. Materials and Methods: Clinical glioma samples were cumulatively collected for the identification of caprin-1 using immunoblot analysis and immunofluorescence detection. DBTRG cells transfected with caprin-1-specific small interfering RNA (siRNA) were used to verify caprin-1s oncogenic function using a real-time cell analyzer (RTCA) and scratch assay. Results: Seven of eight collected glioma samples were identified as positive for caprin-1 expression. siRNA dose-responsive inhibition of cell proliferation was observed in DBTRG cells with RTCA, and cell migration rate was significantly reduced by siRNA transfection (P < 0.05). Conclusion: The present study identified the higher expression of caprin-1 in human glioblastoma-derived DBTRG cells. Its oncogenic functions, mainly enhanced cell proliferation and promoted cell migration capacity, were also verified in these cells. This study provided fundamentals for developing caprin-1 as a therapeutic target for the treatment of gliomas.