Huang, Peng

Extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) exhibit great therapeutic potential in ischemia-associated conditions and diseases such as myocardial infarction, ischemic stroke, and wound healing. Enhancing the therapeutic efficacy of MSC-EVs could advance their clinical application. Diverse cargos (proteins, mRNA, microRNA, etc.) in MSC-EVs contribute to the therapeutic effects in various diseases. Vascular endothelial growth factor (VEGF) is one of the primary driving molecules in promoting angiogenesis and protecting endothelial cells lining blood vessels from apoptosis. In this study, we explored the feasibility of engineering parent MSCs with VEGF mRNA to potentiate therapeutic effects of their derived EVs. We first detected elevated levels of VEGF mRNA and protein in transfected MSCs and demonstrated the bioactivity of secreted VEGF by an angiogenesis assay. Furthermore, EVs derived from VEGF mRNA-engineered MSCs (VEGF-MSC-EVs) contained high levels of VEGF mRNA and protein and showed superior ability to protect human umbilical vein endothelial cells (HUVECs) from apoptosis compared to EVs derived from control MSCs (control MSC-EVs). To our knowledge, this is the first report demonstrating that VEGF-MSC-EVs boost therapeutic efficacy by promoting endothelial cell survival. Our findings offer a novel approach for cell-free therapy in ischemia-associated conditions and diseases.

Galactic cosmic ray (GCR) radiation is a major barrier to human space exploration beyond Earth’s magnetic field protection. Mesenchymal stem cells (MSCs) are found in all organs and play a critical role in repair and regeneration of tissue. We engineered bone marrow-derived MSCs and evaluated their response to ionizing radiation exposure. Epidermal growth factor receptor (EGFR) expression by certain types of cancers has been shown to induce radioresistance. In this study, we tested the feasibility of transfecting MSCs to overexpress EGFR (eMSC-EGFR) and their capacity to tolerate and recover from X-ray exposure. Quantitative real-time PCR (qRT-PCR) and immunoblotting results confirmed the efficient transfection of EGFR into MSCs and EGFR protein production. eMSC-EGFR maintained characteristics of human MSCs as outlined by the International Society for Cell & Gene Therapy. Then, engineered MSCs were exposed to various dose rates of X-ray (1–20 Gy) to assess the potential radioprotective role of EGFR overexpression in MSCs. Post-irradiation analysis included evaluation of morphology, cell proliferation, viability, tumorigenic potential, and DNA damage. eMSC-EGFR showed signs of radioresistance compared to naïve MSCs when assessing relative proliferation one week following exposure to 1–8 Gy X-rays, and significantly lower DNA damage content 24 h after exposure to 4 Gy. We establish for the first time the efficient generation of EGFR overexpressing MSCs as a model for enhancing the human body to tolerate and recover from moderate dose radiation injury in long-term manned space travel.

AbstractBackground and ObjectivesIn the setting of tissue hypoxia, S‐nitrosylated haemoglobin (SNO‐Hb) plays crucial roles in the control of blood flow. This is associated with decreased oxygen affinity to haemoglobin and increase in tissue oxygenation. Red blood cell (RBC) transfusion is primarily performed to improve tissue oxygenation in anaemic patients. RBCs after storage undergo a variety of biochemical and functional alterations, including deficiency of nitric oxide (NO) bioactivity. However, how donor characteristics affect NO levels during RBC storage is unclear. We sought to investigate the association of blood donor age, gender and storage duration with NO and SNO‐Hb levels in blood units.Materials and MethodsBlood samples from 42 healthy younger (≤30 years) and older (≥45 years) donors were collected and stored for up to 42 days. Total NO kits were used to detect total nitrite and nitrate levels in blood storage solution. SNO‐Hb levels in RBCs were detected and analysed by quantitative mass spectrometry.ResultsTotal NO levels in the blood storage solution significantly increased with donor age and storage duration. Proteomic analysis revealed that RBCs from older donors, particularly older females, significantly lost SNO‐Hb during storage. Our findings indicate that RBCs from older donors are associated with reduced SNO‐Hb levels and increased NO metabolites in storage solution after ≥35 days storage.ConclusionThe findings suggest stored RBCs from older donors may have reduced capacity to deliver oxygen to tissues under hypoxia. A shorter shelf life may be required for storing RBCs from older donors, particularly older females.

Mesenchymal stem cells (MSCs) are used in various studies to induce immunomodulatory effects in clinical conditions associated with immune dysregulation such as graft versus host disease (GvHD). However, most of these clinical trials failed to go beyond early phase 2 studies because of limited efficacy. Various methods have been assessed to increase the potency of MSCs. IL-10 is an anti-inflammatory cytokine that is known to modulate immune responses in GvHD. In this study, we evaluated the feasibility of transfecting IL-10 mRNA to enhance MSC therapeutic potential. IL-10 mRNA engineered MSCs (eMSCs-IL10) maintained high levels of IL-10 expression even after freezing and thawing. IL-10 mRNA transfection did not appear to alter MSC intrinsic characteristics. eMSCs-IL10 significantly suppressed T cell proliferation relative to naïve MSCs in vitro. In a mouse model for GvHD, eMSCs-IL10 induced a decrease in plasma level of potent pro-inflammatory cytokines and inhibited CD4+ and CD8+ T cell proliferation in the spleen. In summary, our studies demonstrate the feasibility of potentiating MSCs to enhance their immunomodulatory effects by IL-10 mRNA transfection. The use of non-viral transfection may generate a safe and potent MSC product for treatment of clinical conditions associated with immune dysregulation such as GvHD.

Neuroblastoma is derived from the sympathetic neuronal lineage of neural crest cells, and is the most frequently observed of the extracranial pediatric solid tumors. The neuronal differentiation factor, NeuroD1, has previously been shown to promote cell motility in neuroblastoma by suppressing the expression of Slit2. Here we report that NeuroD1 is also involved in the proliferation of neuroblastoma cells, including human cell lines and primary tumorspheres cultured from the tumor tissues of model mice. Interestingly, the growth inhibition of neuroblastoma cells induced by knockdown of NeuroD1 was accompanied by a reduction of ALK expression. ALK is known to be one of the important predisposition genes for neuroblastoma. The phenotype resulting from knockdown of NeuroD1 was suppressed by forced expression of ALK and, therefore, NeuroD1 appears to act mainly through ALK to promote the proliferation of neuroblastoma cells. Furthermore, we showed that NeuroD1 directly bound to the promoter region of ALK gene. In addition, the particular E‐box in the promoter was responsible for NeuroD1‐mediated ALK expression. These results indicate that ALK should be a direct target gene of NeuroD1. Finally, the expressions of NeuroD1 and ALK in the early tumor lesions of neuroblastoma model mice coincided in vivo. We conclude that the novel mechanism would regulate the expression of ALK in neuroblastoma and that NeuroD1 should be significantly involved in neuroblastoma tumorigenesis.