Both mesenchymal stem cells (MSCs) and their corresponding small extracellular vesicles (sEVs, commonly referred to as exosomes) share similar immunomodulatory properties that are potentially beneficial for the treatment of acute graft versus host disease (aGvHD). We report that clinical grade Wharton's Jelly‐derived MSCs (WJMSCs) secrete sEVs enriched in programmed death‐ligand 1 (PD‐L1), an essential ligand for an inhibitory immune checkpoint. A rapid increase in circulating sEV‐associated PD‐L1 was observed in patients with aGvHD and was directly associated with the infusion time of clinical grade WJMSCs. In addition, in vitro inhibitory antibody mediated blocking of sEV‐associated PD‐L1 restored T cell activation (TCA), suggesting a functional inhibitory role of sEVs‐PD‐L1. PD‐L1‐deficient sEVs isolated from WJMSCs following CRISPR‐Cas9 gene editing fail to inhibit TCA. Furthermore, we found that PD‐L1 is essential for WJMSC‐derived sEVs to modulate T cell receptors (TCRs). Our study reveals an important mechanism by which therapeutic WJMSCs modulate TCR‐mediated TCA through sEVs or sEV‐carried immune checkpoints. In addition, our clinical data suggest that sEV‐associated PD‐L1 may be not only useful in predicting the outcomes from WJMSC clinical administration, but also in developing cell‐independent therapy for aGvHD patients.
Psoriasis is a dermatologic disease of immune origins with no definitive cure. We report the Makati Medical Center experience of utilizing autologous mesenchymal stromal cells (MSCs) for one patient with psoriasis vulgaris (PV) and another with psoriatic arthritis (PA). Patients were educated and gave informed consent, according to the principles of the Declaration of Helsinki. The protocol was approved by the Cellular Transplantation Ethics Committee of the Makati Medical Center. Autologous MSCs were cultured from lipoaspirate and expanded in a clean room class 100 facility (Cellular Therapeutics Center, Makati Medical Center). MSCs were infused intravenously at a dose of 0.5-3.1 million cells/kg after complying with quality control parameters. Psoriasis area and severity index (PASI) evaluations were conducted by third-party dermatologists. The PA patient, who was previously unresponsive to standard treatment modalities, demonstrated a decrease in PASI (from 21.6 to 9.0, mild state after two infusions). No improvements were noted in joint pain until further treatment with etanercept and infliximab. The PV patient, who was previously dependent on methotrexate, showed a decrease in PASI from 24.0 to 8.3 after three infusions; this clinical improvement was sustained for 292 days (9.7 months) without methotrexate. The PV patient illustrated a marginal reduction in serum tumor necrosis factor-a (TNF-a), while significant (3.5-to 5-fold) decreases in reactive oxygen species (ROS) activity were noted. The ROS levels correlated with the clinical improvement of the PV patient. No serious adverse events were noted for either patient as a result of MSC infusions. This report demonstrates safe and tolerable transplantation of autologous MSCs for the treatment of psoriasis and warrants large clinical studies to investigate the long-term safety and efficacy of this approach.
More than two-thirds of all women diagnosed with epithelial ovarian cancer (EOC) will die from the disease (>14,000 deaths annually), a fact that has not changed considerably in the last three decades. Although the 5-year survival rates for most other solid tumors have improved steadily, ovarian cancer remains an exception, making it the deadliest of all gynecologic cancers and five times deadlier than breast cancer. When diagnosed early, treatment is more effective, with a 5-year survival rate of up to 90%. Unfortunately, most cases are not detected until after the cancer has spread, resulting in a dismal 5-year survival rate of less than 30%. Current screening methods for ovarian cancer typically use a combination of a pelvic examination, transvaginal ultrasonography, and serum cancer antigen 125 (CA125), but these have made minimal impact on improving mortality. Thus, there is a compelling unmet need to develop new molecular tools that can be used to diagnose early-stage EOC and/or assist in the clinical management of the disease after a diagnosis, given that more than 220,000 women are living with ovarian cancer in the United States and are at risk of recurrence. Here, we discuss the state of advancing liquid-based approaches for improving the early detection of ovarian cancer.See all articles in this Special Collection Honoring Paul F. Engstrom, MD, Champion of Cancer Prevention
Natural killer group 2 member D (NKG2D) is a strong NK cell activating receptor, with engagement by ligands triggering granule release and cytokine production. The function of NKG2D signaling in NK cells has largely been studied in the context of engagement of the receptor by ligands expressed on the surface of target cells. We report that upon activation with IL-12, IL-15 and IL-18, human NK cells express NKG2D ligands of the UL16 binding protein (ULBP) family on the cell surface. NKG2D-ligand interaction between cytokine-stimulated NK cells increases the activity of the metalloprotease TNF-α-converting enzyme (TACE). This enhanced TACE activity significantly increases the release of TNF-α and ULBP proteins from the surface of the NK cells. These results demonstrate that NKG2D signaling is critical for maximal TNF-α release by NK cells. Further, they are the first to demonstrate a role for NKG2D-ligand interaction via homotypic NK cell contact in NK cell effector function.
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