Olfactory mucosa contains neural stem cells, called olfactory stem cells (OSCs), which produce trophic support required for promoting axonal regeneration after nerve injury. However, the local tissue environment can reduce the viability/function of transplanted cells when placed directly on the injury. Although gelatin hydrogels have been shown to aid cell survival during transplantation, such OSC-hydrogel combinations have not been extensively tested, particularly during recovery from facial nerve palsy. In this study, OSCs were isolated from the olfactory mucosae of newborn mice and were shown to express neural stem cell markers before differentiation, as well as cell-type specific markers after differentiation, confirming their multipotency. The OSCs also secrete growth factors and various cytokines that promote nerve regeneration. To test the effects of OSC transplantation in vivo, Medgel, a biodegradable hydrogel sponge, was applied to retain OSCs around the injury site and to lessen the detrimental effects of the local environment in an established facial nerve palsy mouse model. When OSCs were transplanted into the injury site, accelerated recovery was observed for 1 week. When OSCs were transplanted with Medgel, a higher level and duration of accelerated recovery was observed. OSCs in Medgel also increased peripheral nerve function and increased the number of regenerated nerve fibers. These results suggest that OSCs implanted with Medgel accelerate and enhance recovery from facial palsy in mice. Because human OSCs can be easily obtained from olfactory mucosa biopsies with limited risk, this OSC-Medgel combination is a candidate treatment option for accelerating recovery after facial nerve injury. Stem Cells Translational Medicine 2019;8:169&10

Recent developments in therapeutic strategies have improved the prognosis of head and neck squamous cell carcinoma (HNSCC). Nevertheless, 5-year survival rate remains only 40%, necessitating new therapeutic agents. Oncolytic virotherapy entails use of replication-competent viruses to selectively kill cancer cells. We aimed to explore the potential of HF10 as an oncolytic virus against human or mouse HNSCC cell lines, and primary-cultured HNSCC cells. HF10 replicated well in all the HNSCC cells, in which it induced cytopathic effects and cell killing. Next, we investigated the oncolytic effects of HF10 in ear tumor models with human or mouse tumor cells. We detected HF10-infected cells within the ear tumors based on their expression of green fluorescent protein. HF10 injection suppressed ear tumor growth and prolonged overall survival. In the syngeneic model, HF10 infection induced tumor necrosis with infiltration of CD8-positive cells. Moreover, the splenocytes of HF10-treated mice released antitumor cytokines, IL-2, IL-12, IFN-alpha, IFN-beta, IFN-gamma, and TNF-alpha, after stimulation with tumor cells in vitro. The HF10-treated mice that survived their original tumor burdens rejected tumor cells upon re-challenge. These results suggested that HF10 killed HNSCC cells and induced antitumoral immunity, thereby establishing it as a promising agent for the treatment of HNSCC patients.

Hepatocyte growth factor (HGF) promotes regeneration of the central nervous system, but its effects on the peripheral nervous system remain unclear. This study was conducted to elucidate the effect of HGF on regeneration of the murine facial nerve after crush injury. To do so, a replication-defective herpes simplex virus vector that incorporated HGF was prepared (HSV-HGF). The main trunk of the facial nerve was compressed by mosquito hemostats, and HSV-HGF, control vector or medium was then applied to the compressed nerve. We found that mice in the HGF group required significantly fewer days for complete recovery from nerve compression. Furthermore, the amplitude of the evoked buccinator muscle compound action potential increased following HSV-HGF application. HGF expression in and around the compressed nerve was demonstrated by enzyme-linked immunoassay and immunohistochemistry. In addition, HSV-HGF introduction around the damaged nerve significantly accelerated recovery of function of the facial nerve. These data suggest a possible role of HGF in promoting facial nerve regeneration after nerve damage. Furthermore, this viral delivery method may be applied clinically for many types of severe facial palsy during facial nerve decompression surgery.

T follicular regulatory cells (Tfr) play a pivotal role in maintaining immune self-tolerance and prevention of autoantibody induction. However, the stages of Tfr formation have still not been clarified. Here, we found that 30 to 50% of circulating Tfr in human blood have a naïve-like phenotype (preTfr, CD45RA ⁺ CD45RO ⁻ Foxp3 ⁺ CXCR5 ⁺ ). PreTfr are expandable in vitro while retaining suppressive capacity. They are transcriptionally similar to naïve T _regs (nT _regs ) ex vivo, but after stimulation, they gain increased expression of Tfr-related suppressive molecules such as IL-1RA, suggesting that they are primed for full differentiation into mature Tfr. Further, we demonstrate that preTfr but not nT _reg are significantly reduced in the blood of patients with COVID-19 and patients with sepsis and that this loss is correlated with increased anti–interferon-γ antibodies and activated atypical B cells. Together, these data suggest that Tfr are disrupted at the earliest stage of their formation during severe disease and may be an important therapeutic target in future vaccine developments.

Prognosis for advanced oral carcinoma remains poor. Oncolytic virotherapy uses replication-competent viruses to infect and kill only the tumor cells. However, it has been difficult to investigate the oncolytic activity of viruses against oral carcinomas in mouse models. This study established a mouse model of oral cancer and investigated the in vitro and in vivo anti-tumor effects of HF10, a highly attenuated, replication-competent herpes simplex virus (HSV)-1. Mouse tongue cancer was induced by injecting 4-nitroquinoline 1-oxide into the mouse tongue. The murine oral cancer cell line isolated from this tumor, named NMOC1, formed invasive carcinoma within a week when injected into mouse tongue. HF10 successfully infected, replicated, and spread in the cancer cells in vitro. HF10 was able to kill cancer cells isolated from human or mouse tongue tumor. HF10 injection into tongue carcinomas prolonged mouse survival without any side effects or weight loss. Intertumoral injection of GFP-expressing HF10 confirmed that viral spread was confined within the tumors. Immunohistochemical staining showed that HF10 induced infiltration of CD8-positive T cells around HSV-infected cells in the tumor mass, implying increased anti-tumor immunity. We successfully established an oral cancer cell line and showed that HF10 is a promising therapeutic agent for oral cancer.