Photobiomodulation, by utilizing low-power light in the visible and near-infrared spectra to trigger biological responses in cells and tissues, has been considered as a possible therapeutic strategy for Alzheimer’s disease (AD), while its specific mechanisms have remained elusive. Here, we demonstrate that cognitive and memory impairment in an AD mouse model can be ameliorated by 1070-nm light via reducing cerebral β-amyloid (Aβ) burden, the hallmark of AD. The glial cells, including microglia and astrocytes, play important roles in Aβ clearance. Our results show that 1070-nm light pulsed at 10 Hz triggers microglia rather than astrocyte responses in AD mice. The 1070-nm light-induced microglia responses with alteration in morphology and increased colocalization with Aβ are sufficient to reduce Aβ load in AD mice. Moreover, 1070-nm light pulsed at 10 Hz can reduce perivascular microglia and promote angiogenesis to further enhance Aβ clearance. Our study confirms the important roles of microglia and cerebral vessels in the use of 1070-nm light for the treatment of AD mice and provides a framework for developing a novel therapeutic approach for AD.

Bone marrow‐derived mesenchymal stem cells (MSCs) can localize in injured, inflamed, and cancerous tissues after systemic infusion. However, the dynamic homing profile of MSCs in the peripheral blood is not well characterized. Here, using in vivo flow cytometry to noninvasively monitor the dynamics of fluorescence‐labeled cells, we found different clearance kinetics of systemically infused MSCs between healthy and tumor mouse models. The circulation times of MSCs in healthy mice and mice with subcutaneous tumors, orthotopically transplanted liver tumors, or metastatic lung tumors were 30, 24, 18, and 12 hours, respectively, suggesting that MSCs actively home to tumor environments. MSCs infiltrated into hepatocellular carcinoma (HCC) sites and preferentially engrafted to micrometastatic regions both in vivo and in vitro. The expression of epidermal growth factor, CXCL9, CCL25, and matrix metalloproteinases‐9 by HCC cells differed between primary tumor sites and metastatic regions. By characterizing the homing profiles of systemically perfused MSCs under physiological and cancerous conditions, these findings increase our understanding of the migration of MSCs from the circulation to tumor sites and constitute a basis for developing MSC‐based anti‐cancer therapeutic strategies. Stem Cells Translational Medicine 2017;6:1120–1131

Circulating tumor cells (CTCs) is an established biomarker of cancer metastasis. The circulation dynamics of CTCs are important for understanding the mechanisms underlying tumor cell dissemination. Although studies have revealed that the circadian rhythm may disrupt the growth of tumors, it is generally unclear whether the circadian rhythm controls the release of CTCs. In clinical examinations, the current in vitro methods for detecting CTCs in blood samples are based on a fundamental assumption that CTC counts in the peripheral blood do not change significantly over time, which is being challenged by recent studies. Since it is not practical to draw blood from patients repeatedly, a feasible strategy to investigate the circadian rhythm of CTCs is to monitor them by in vivo detection methods. Fluorescence in vivo flow cytometry (IVFC) is a powerful optical technique that is able to detect fluorescent circulating cells directly in living animals in a noninvasive manner over a long period of time. In this study, we applied fluorescence IVFC to monitor CTCs noninvasively in an orthotopic mouse model of human prostate cancer. We observed that CTCs exhibited stochastic bursts over cancer progression. The probability of the bursting activity was higher at early stages than at late stages. We longitudinally monitored CTCs over a 24-h period, and our results revealed striking daily oscillations in CTC counts that peaked at the onset of the night (active phase for rodents), suggesting that the release of CTCs might be regulated by the circadian rhythm.

Circulating tumor cell (CTC) clusters are found among CTCs and show significantly greater potential for an important role in cancer metastasis than single CTCs, which have been traditionally believed as the majority of CTCs. The accurate proportion and dynamics of CTC clusters remain unclear due to the fact that CTCs in blood flow are very difficult to detect in vivo and in vitro. CTC clusters are even more difficult to be distinguished from CTCs without perturbation by state-of-the-art detection methods. Here, we demonstrate that by using in vivo flow cytometry (IVFC), we can reliably measure the proportion and dynamics of CTC clusters in two murine tumor models. CTC clusters are easily identified by their unique fluorescent pattern with multiple peaks and wider time duration. We find that the proportion of CTC clusters increases significantly during cancer metastasis in both mouse models, the orthotopic liver cancer and the subcutaneous prostate cancer models. Our results suggest that CTC clusters account for a much larger proportion of CTCs than previously anticipated. Hence this report might provide a new-level of understanding of CTCs during cancer development and progression. V C 2016 International Society for Advancement of Cytometry Key terms circulating tumor cell; cancer metastasis; in vivo flow cytometry; murine tumor models CANCER metastasis accounts for the major cause of mortality in cancer patients. It has been found that circulating tumor cells (CTCs) play an important role in cancer metastasis in which individual CTC cells are believed to be a great majority and mainly responsible in cancer metastasis (1). However, recent findings of CTC clusters have challenged this understanding by reporting that CTC clusters present up to 50-fold increased metastatic potential than individual CTCs (2). Currently, CTC clusters are considered to account for <9% of the total CTCs in both human patients and animal models, based on in vitro quantification methods, such as immunemagnetic platforms and microchips (2,3). However, this value may not be accurate due to the lack of state-of-the-art in vitro detection methods. This difficulty can be related to the fact that CTC clusters are scattered and are therefore inevitably difficult to detect in the purification process of blood samples (4-6). In addition, the limited imaging speed of intravital microscopy, usually <30 frames per second, makes it hard to observe CTCs in blood flow. Thus, the accurate proportion and dynamics of CTC clusters in vivo remain unclear.To study CTCs in blood flow in vivo, the technique of in vivo flow cytometry (IVFC) has been developed which has the advantage that no blood drawing and blood sample preparation are needed (7-9). It utilizes the blood flow as natural sheath flow of (ex vivo) flow cytometry. We have therefore used this technique to detect CTC clusters to monitor cancer progression in murine tumor models. In this report, we present the proportion and dynamics of CTC clusters in cancer metastasis in orthotopic liver ca...

Herpes simplex virus 1 (HSV-1) spreads in populations through a latency entry and reactivation cycle. The role of host immune-suppressive factor regulatory T cells (Treg cells) in controlling latency establishment and reactivation is not completely understood. Here, using an HSV-1 ocular infection murine model, we observe a positive correlation between the level of Treg cells and viral infectivity and demonstrate the requirement for Treg cells in latency establishment. Furthermore, we show that host stress leads to HSV-1 reactivation via increased Treg cell control of CD8 + T cells, permitting viral replication under diminished immune surveillance. Together, we propose that Treg cell regulation may serve as a key target for controlling HSV infection.