The tumor microenvironment affects the outcome of radiotherapy against head and neck squamous cell carcinoma (HNSCC). We recently found that tolerogenic myeloid cells accumulate in the circulation of HNSCC patients undergoing radiotherapy. Here, we analyzed tumor-containing lymph node biopsies collected from these patients. After 2 weeks of radiotherapy, we found an increase in tumor-associated macrophages (TAMs) with activated STAT3, while CD8⁺ T cells were reduced as detected using multiplex IHC. Gene expression profiling indicated upregulation of M2 macrophage–related genes (CD163, CD206), immunosuppressive mediators (ARG1, LIF, TGFB1), and Th2 cytokines (IL4, IL5) in irradiated tumors. We next validated STAT3 as a potential target in human HNSCC-associated TAMs, using UM-SCC1 xenotransplants in humanized mice. Local injections of myeloid cell–targeted STAT3 antisense oligonucleotide (CpG-STAT3ASO) activated human DCs/macrophages and promoted CD8⁺ T cell recruitment, thereby arresting UM-SCC1 tumor growth. Furthermore, CpG-STAT3ASO synergized with tumor irradiation against syngeneic HPV⁺ mEERL and HPV^– MOC2 HNSCC tumors in mice, triggering tumor regression and/or extending animal survival. The antitumor immune responses were CD8⁺ and CD4⁺ T cell dependent and associated with the activation of antigen-presenting cells (DCs/M1 macrophages) and increased CD8⁺ to regulatory T cell ratio. Our observations suggest that targeted inhibition of STAT3 in tumor-associated myeloid cells augments the efficacy of radiotherapy against HNSCC.

The therapeutic potential of exosomes (Exos), a subpopulation of extracellular vesicles (EVs) secreted by various cell types, has been broadly emphasized. Exos are endosome-derived membrane-bound vesicles 50–150 nm in size. Exos can be general or cell type-specific. Their contents enable them to function as multi-signaling and vectorized vehicles. Exos are important for maintaining cellular homeostasis. They are released into extracellular spaces, leading to uptake by neighboring or distant cells and delivering their contents to modulate cell signaling. Exos influence tissue responses to injury, infection, and disease by fusion with the target cells and transferring their cargo, including cytokines, growth and angiogenic factors, signaling molecules, lipids, DNA, mRNAs, and non-coding RNAs. They are implicated in various physiological and pathological conditions, including ocular surface events, such as corneal scarring, wound healing, and inflammation. Their biocompatibility, stability, low immunogenicity, and easy detectability in bodily fluids (blood, tears, saliva, and urine) make them promising tools for diagnosing and treating ocular diseases. The potential to engineer specific Exo cargos makes them outstanding therapeutic delivery vehicles. The objective of this review is to provide novel insights into the functions of Exo cargos and their applications as biomarkers and therapeutics, or targets in the cornea.

Mesenchymal progenitor cells (MPC) are effective in reducing tissue loss, preserving white matter, and improving forelimb function after a spinal cord injury (SCI). We proposed that by preconditioning the mouse by the intravenous delivery (IV) of MPCs for 24 h following SCI, this would provide a more favorable tissue milieu for an NSC intraspinal bridging transplantation at day three and day seven. In combination, these transplants will provide better anatomical and functional outcomes. The intravenous MSCs would provide cell protection and reduce inflammation. NSCs would provide a tissue bridge for axonal regeneration and myelination and reconnect long tract spinal pathways. Results showed that initial protection of the injury site by IV MPCs transplantation resulted in no increased survival of the NSCs transplanted at day seven. However, integration of transplanted NSCs was increased at the day three timepoint, indicating MPCs influence very early immune signaling. We show, in this study, that MPC transplantation resulted in a co-operative NSC cell survival improvement on day three post-SCI. In addition to increased NSC survival on day three, there was an increase in NSC-derived mature oligodendrocytes at this early timepoint. An in vitro analysis confirmed MPC-driven oligodendrocyte differentiation, which was statistically increased when compared to control NSC-only cultures. These observations provide important information about the combination, delivery, and timing of two cellular therapies in treating SCI. This study provides important new data on understanding the MPC inflammatory signaling within the host tissue and timepoints for cellular transplantation survival and oligodendroglia differentiation. These results demonstrate that MPC transplantation can alter the therapeutic window for intraspinal transplantation by controlling both the circulating inflammatory response and local tissue milieu.

Cellular transplantation therapies have been extensively used in experimental spinal cord injury research. However, there is no consensus as to what the most effective cellular controls for the therapeutic cell of interest are. For this reason, we examined whether dead cells obtained through prolonged heat treatment can act as an appropriate cellular control for intravenously injected Sca-1+ mesenchymal precursor cells (MPCs) in C5 unilateral contusion cervical spinal cord injury. This was tested in single intravenous MPC injection alone or intravenous MPC plus intraspinal neural stem cell (NSC) combinatory transplantation studies. MPCs were isolated from the compact bone of FVB mice, while NSCs were isolated from the subventricular zone of luciferase–GFP transgenic FVB mice. Dead MPCs were obtained by heating at 72 °C for at least 12 h. In the MPC only transplant study, injured mice received an injection of 1 × 10⁶ dead or live MPCs D1 post-injury. Mice were then sacrificed at 8 weeks post-injury. In this study, intravenous injections of dead MPCs showed no statistical difference in injured paw usage compared to live MPCs, but behavior was improved compared to the media-vehicle-only control at D7 and D21. In the combinatory MPC plus NSC transplant study, injured mice received an intravenous injection of 1 × 10⁶ dead or live MPCs D1 post-injury followed by intraspinal injection of 100,000 NSCs at D3 or D7 post-injury. Another two cohorts of mice received only NSCs at D3 or D7 post-injury. Mice were then sacrificed at 6 weeks post-injury. In this study, there was no functional difference in any of the groups in the dual injection study. Morphologically, mice receiving IV injection of dead MPCs had a smaller lesion size compared to the vehicular control, but the lesion size was larger than that of the lesion size in mice receiving live MPC injection. Dead cells elicited functional and anatomical benefits for the spinal-cord-injured mice. In summary, dead cells obtained through prolonged heat treatment proved to be inconsistent and not optimal for use as cellular controls for cell transplantation studies in spinal cord injury but provide positive evidence for non-transplantation-based cell therapies.