Algorithm to identify circulating tumor cell clusters using in vivo flow cytometer

Recent studies in oncology have addressed the importance of detecting circulating tumor cell clusters because circulating tumor cell clusters might survive and metastasize more easily than single circulating tumor cells.Signals with larger peak widths detected by in vivo flow cytometer(IVFC)have been used to identify cell clusters in previous studies.However,the accuracy of this criterion might be greatly degraded by variance in blood°ow and the rolling behaviors of circulating tumor cells.Here,we propose a criterion and algorithm to distinguish cell clusters from single cells.In this work,we first used area-based and volume-based models for single°uorescent cells.Simulating each model,we analyzed the corresponding morphology of IVFC signals from cell clusters.According to the Rayleigh criterion,the valley between two adjacent peak signals from two distinguishable cells should be lower than 73.5%of the peak values.A novel signal processing algorithm for IVFC was developed based on this criterion.The results showed that cell clusters can be reliably identied using our proposed algorithm.Intravital imaging was also performed to further support our algorithm.With enhanced accuracy,IVFC is a powerful tool to study circulating cell clusters.

Binary organic nanoparticles with enhanced reactive oxygen species generation capability for photodynamic therapy

Photodynamic therapy(PDT)takes advantage of photosensitizers(PSs)to generate reactive oxygen species(ROS)for cell killing when excited by light.It has been widely used in clinic for therapy of multiple cancers.Currently,all the FDA-approved PSs,including porphyrin,are all small organic molecules,suffering from aggregation-caused quenching(ACQ)issues in biological environment and lacking tumor targeting capability.Nanoparticles(NPs)with size between 20 nm and 200 nm possess tumor targeting capability due to the enhanced permeability and retention(EPR)effect.It is urgent to develop a new strategy to form clinical-approved-PSs-based NPs with improved ROS generation capability.In this study,we report a strategy to overwhelm the ACQ of porphyrin by doping it with a type of aggregation-induced emission(AIE)luminogen to produce a binary NPs with high biocompatibility,and enhanced fluorescence and ROS generation capability.Such NPs can be readily synthesized by mixing a porphyrin derivative,Ce6 with a typical AIE luminogen,TPE-Br.Here,our experimental results have demonstrated the feasibility and effectiveness of this strategy,endowing it a great potential in clinical applications.

In vivo flow cytometry reveals a circadian rhythm of circulating tumor cells

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.Fluoresce nee in vivo flow cytometry(IVFC)is a powerful optical technique that is able to detect fluoresce nt 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.

Microglia modulation with 1070-nm light attenuates Aβ burden and cognitive impairment in Alzheimer’s disease mouse model

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 cerebralβ-amyloid(Aβ)burden,the hallmark of AD.The glial cells,including microglia and astrocytes,play important roles in Aβclearance.Our results show that 1070-nm light pulsed at 10 Hz triggers microglia rather than astrocyte responses in AD mice.The 1070-nm lightinduced microglia responses with alteration in morphology and increased colocalization with Aβare sufficient to reduce Aβload in AD mice.Moreover,1070-nm light pulsed at 10 Hz can reduce perivascular microglia and promote angiogenesis to further enhance Aβclearance.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.

Reply to Comment on “In vivo flow cytometry reveals a circadian rhythm of circulating tumor cells”

Dear Editor,We thank Niedre et al.for their correspondence regarding our recent paper1.They proposed a point that the temporal distribution of circulating tumor cells(CTCs)monitored by diffuse in vivo flow cytometry in a multiple myeloma mouse model in their previous work2 might be different from our results.Niedre et al.claimed that CTC detection statistics deviated from Poisson but did not found circadian variations in CTC numbers in a multiple myeloma mouse model.They also cite another literature by Juratli.et al.3,in which the authors reported that CTC numbers did not always correlate with tumor size during cancer progression.However,by establishing an orthotopic mouse model of prostate cancer and utilizing the technology in vivo flow cytometry(IVFC),we found CTCs exhibited bursting activity and daily oscillation in an orthotopic model of prostate cancer.