PD-1/CD80+ small extracellular vesicles from immunocytes induce cold tumours featured with enhanced adaptive immunosuppression.

Only a minority of cancer patients benefit from immune checkpoint blockade therapy. Sophisticated cross-talk among different immune checkpoint pathways as well as interaction pattern of immune checkpoint molecules carried on circulating small extracellular vesicles (sEV) might contribute to the low response rate. Here we demonstrate that PD-1 and CD80 carried on immunocyte-derived sEVs (I-sEV) induce an adaptive redistribution of PD-L1 in tumour cells. The resulting decreased cell membrane PD-L1 expression and increased sEV PD-L1 secretion into the circulation contribute to systemic immunosuppression. PD-1/CD80+ I-sEVs also induce downregulation of adhesion- and antigen presentation-related molecules on tumour cells and impaired immune cell infiltration, thereby converting tumours to an immunologically cold phenotype. Moreover, synchronous analysis of multiple checkpoint molecules, including PD-1, CD80 and PD-L1, on circulating sEVs distinguishes clinical responders from those patients who poorly respond to anti-PD-1 treatment. Altogether, our study shows that sEVs carry multiple inhibitory immune checkpoints proteins, which form a potentially targetable adaptive loop to suppress antitumour immunity.

Spatiotemporal characteristics of tissue derived small extracellular vesicles is associated with tumor relapse and anti-PD-1 response.

Small extracellular vesicles (sEVs) residing at tumor tissues are valuable specimens for biopsy. Tumor heterogeneity is common across all cancer types, but the heterogeneity of tumor tissue-derived sEVs (Ti-sEVs) is undefined. This study aims to discover the spatial distributions of Ti-sEVs in oral squamous cell carcinoma (OSCC) tissues and explore how these vesicle distributions affect the patients' prognosis. Multi-regional sampling enabled us to uncover that Ti-sEVs' accumulation at peritumoral sites correlates with a higher disease-free survival rate, and conversely, sparse peritumoral Ti-sEVs tend to forecast a higher risk of relapse. Of those relapsed patients, Ti-sEVs strongly bind to extracellular matrix and subsequently degrade it for allowing themselves enter the bloodstream rather than staying in situ. In advanced OSCC patients, the quantity and spatial distribution of Ti-sEVs prior to anti-PD-1 treatment, as well as the temporal variance of Ti-sEVs before and after immunotherapy, strongly map the clinical response and can help to distinguish the patients with shrinking tumors from those with growing tumors. Our work elucidates the correlation of spatiotemporal features of Ti-sEVs with patients' therapeutic outcomes and exhibit the potential for using Ti-sEVs as a predictor to forecast prognosis and screen the responders to anti-PD-1 therapy.

Red Blood Cell-Derived Extracellular Vesicles: An Overview of Current Research Progress, Challenges, and Opportunities.

Red blood cell-derived extracellular vesicles (RBC EVs) are small, spherical fragments released from red blood cells. These vesicles, similar to EVs derived from other cell types, are crucial for intercellular communication processes and have been implicated in various physiological and pathological processes. The diagnostic and therapeutic potential of RBC EVs has garnered increasing attention in recent years, revealing their valuable role in the field of medicine. In this review, we aim to provide a comprehensive analysis of the current research status of RBC EVs. We summarize existing studies and highlight the progress made in understanding the characteristics and functions of RBC EVs, with a particular focus on their biological roles in different diseases. We also discuss their potential utility as diagnostic and prognostic biomarkers in diseases and as vectors for drug delivery. Furthermore, we emphasize the need for further research to achieve selective purification of RBC EVs and unravel their heterogeneity, which will allow for a deeper understanding of their diverse functions and exploration of their potential applications in diagnostics and therapeutics.

Overexpression of RAB27A in Oral Squamous Cell Carcinoma Promotes Tumor Migration and Invasion via Modulation of EGFR Membrane Stability.

Oral squamous cell carcinoma (OSCC) is the most prevalent subtype of head and neck tumors, highly prone to lymph node metastasis. This study aims to examine the expression pattern of Ras-related protein Rab-27A (RAB27A) and explore its potential implications in OSCC. The expression of RAB27A was assessed through immunohistochemical analysis utilizing tissue microarrays. In vitro experiments were conducted using RAB27A-knockdown cells to investigate its impact on OSCC tumor cells. Additionally, transcriptome sequencing was performed to elucidate potential underlying mechanisms. RAB27A was significantly overexpressed in OSCC, and particularly in metastatic lymph nodes. It was positively correlated with the clinical progression and poor survival prognosis. Silencing RAB27A notably decreased the proliferation, migration, and invasion abilities of OSCC cells in vitro. A Gene Ontology (GO) enrichment analysis indicated a strong association between RAB27A and the epidermal growth factor receptor (EGFR) signaling pathway. Further investigations revealed that RAB27A regulated the palmitoylation of EGFR via zinc finger DHHC-type containing 13 (ZDHHC13). These findings provide insights into OSCC progression and highlight RAB27A as a potential therapeutic target for combating this aggressive cancer.

Continuous magnetic separation microfluidic chip for tumor cell in vivo detection.

Continuously recording the dynamic changes of circulating tumor cells (CTCs) is crucial for tumor metastasis. This paper creates a continuous magnetic separation microfluidic chip that enables rapid and continuous in vivo cell detection. The chip shows its potential to study tumor cell circulation in the blood, offering a new platform for studying the cellular mechanism of tumor metastasis.

p-AKT/VPS4B regulates the small extracellular vesicle size in venous malformation endothelial cells.

OBJECTIVE: Small extracellular vesicle (sEV)-mediated intercellular communication is increasingly the key for the understanding of venous malformations (VMs). This study aims to clarify the detailed changes of sEVs in VMs. SUBJECTS AND METHODS: Fifteen VM patients without treatment history and twelve healthy donors were enrolled in the study. sEVs were isolated from both fresh lesions and cell supernatant, and were examined by western blotting, nanoparticle tracking analysis and transmission electron microscopy. Western blot analysis, immunohistochemistry and immunofluorescence were adopted to screening candidate regulator of sEV size. Specific inhibitors and siRNA were employed to validate the role of dysregulated p-AKT/vacuolar protein sorting-associated protein 4B (VPS4B) signaling on the size of sEVs in endothelial cells. RESULTS: The size of sEVs derived from both VM lesion tissues and cell model was significantly increased. VPS4B, whose expression level was mostly significantly downregulated in VM endothelial cells, was responsible for the size change of sEVs. Targeting abnormal AKT activation corrected the size change of sEVs by recovering the expression level of VPS4B. CONCLUSION: Downregulated VPS4B in endothelial cells, resulted from abnormally activated AKT signaling, contributed to the increased size of sEVs in VMs.

Three-Dimensional Magnetic Chip with Extracorporeal Circulation for Circulating Tumor Cell In Vivo Detection and Tumor Growth Inhibition.

Liquid biopsy technology involves taking samples from body fluids in a minimally invasive way and analyzing tumor markers to achieve early diagnosis and efficacy evaluation of tumors. The development of real-time cancer diagnosis and treatment strategies based on liquid biopsy technology is of great significance to cancer management. This paper described an extracorporeal circulation based on a three-dimensional (3D) magnetic chip (3DMC-system) for in vivo detection and real-time monitoring of circulating tumor cells (CTCs). Utilizing biofunctionalized magnetic nanospheres (MNs) with CTC recognition function, this 3DMC-system could effectively achieve the real-time monitoring of CTCs in vivo with good stability and strong anti-interference. Compared with in vitro CTC detection, in vivo detection could not only detect more CTCs but also detect the presence of CTCs in the blood at an early stage of the tumor, when tumor metastasis is not observed in imaging. In addition, due to the flexibility of the chip design, the system can easily add a treatment module to integrate cancer diagnosis and treatment together. With good biocompatibility and high stability, this 3DMC-system is expected to provide a new personalized medical program for cancer patients.

ALIX promotes cell migration and invasion of head and neck squamous cell carcinoma by regulating the expression of MMP9, MMP14, VEGF-C.

OBJECTIVE: The poor survival rate of head and neck squamous cell carcinoma (HNSCC), one of the most prevalent human cancer, is attributed to frequent locoregional recurrence and lymph node metastases. Though it is reported that the expression of ALG-2 interacting protein X (ALIX) closely correlates with the progression of various tumors, its role in HNSCC remains unclear. The present study aims to investigate the role of ALIX in the development of HNSCC. DESIGN: With immunohistochemical staining, the expression levels of ALIX and series of related functional proteins were compared in normal mucosal (n = 18), HNSCC tissues (n = 54), and metastatic lymph nodes (n = 11). Further, the correlation analysis was performed among the proteins detected. By knocking down ALIX in HNSCC cell lines, the correlation of ALIX with the proteins was verified in vitro. The role of ALIX in proliferation, migration, and invasion of HNSCC cells was further studied by flow cytometry, wounding healing, and transwell assays, respectively. RESULTS: Higher expression level of ALIX was revealed in HNSCC samples, especially in metastatic lymph nodes, than in normal mucosal tissues. Accordingly, increasing levels of MMP9, MMP14, and VEGF-C were also discovered in metastatic lymph nodes and significantly correlated with the expression of ALIX. In vitro assays demonstrated that the knockdown of ALIX reduced both the transcriptional and protein levels of MMP9, MMP14, and VEGF-C, together with suppressed migration and weakened invasion of HNSCC cell lines. CONCLUSIONS: ALIX up-regulated the expression of MMP9, MMP14 and VEGF-C, and promoted migration and invasion of HNSCC cells.

Real-Time Dissection of the Transportation and miRNA-Release Dynamics of Small Extracellular Vesicles.

Extracellular vesicles (EVs) are cell-derived membrane-enclosed structures that deliver biomolecules for intercellular communication. Developing visualization methods to elucidate the spatiotemporal dynamics of EVs' behaviors will facilitate their understanding and translation. With a quantum dot (QD) labeling strategy, a single particle tracking (SPT) platform is proposed here for dissecting the dynamic behaviors of EVs. The interplays between tumor cell-derived small EVs (T-sEVs) and endothelial cells (ECs) are specifically investigated based on this platform. It is revealed that, following a clathrin-mediated endocytosis by ECs, T-sEVs are transported to the perinuclear region in a typical three-stage pattern. Importantly, T-sEVs frequently interact with and finally enter lysosomes, followed by quick release of their carried miRNAs. This study, for the first time, reports the entire process and detailed dynamics of T-sEV transportation and cargo-release in ECs, leading to better understanding of their proangiogenic functions. Additionally, the QD-based SPT technique will help uncover more secrets of sEV-mediated cell-cell communication.

Graphene Coated Dielectric Hierarchical Nanostructures for Highly Sensitive Broadband Infrared Sensing.

Broadband infrared (IR) absorption is sought after for wide range of applications. Graphene can support IR plasmonic waves tightly bound to its surface, leading to an intensified near-field. However, the excitation of graphene plasmonic waves usually relies on resonances. Thus, it is still difficult to directly obtain both high near-field intensity and high absorption rate in ultra-broad IR band. Herein, a novel method is proposed to directly realize high near-field intensity in broadband IR band by graphene coated manganous oxide microwires featured hierarchical nanostructures (HNSs-MnO@Gr MWs) both experimentally and theoretically. Both near-field intensity and IR absorption of HNSs-MnO@Gr MWs are enhanced by at least one order of magnitude compared to microwires with smooth surfaces. The results demonstrate that the HNSs-MnO@Gr MWs support vibrational sensing of small organic molecules, covering the whole fingerprint region and function group region. Compared with the graphene-flake-based enhancers, the signal enhancement factors reach a record high of 103 . Furthermore, just a single HNSs-MnO@Gr MW can be constructed to realize sensitively photoresponse with high responsivity (over 3000 V W-1 ) from near-IR to mid-IR. The graphene coated dielectric hierarchical micro/nanoplatform with enhanced near-field intensity is scalable and can harness for potential applications including spectroscopy, optoelectronics, and sensing.

HRS Regulates Small Extracellular Vesicle PD-L1 Secretion and Is Associated with Anti-PD-1 Treatment Efficacy.

PD-L1 localized to immunosuppressive small extracellular vesicles (sEV PD-L1) contributes to tumor progression and is associated with resistance to immune-checkpoint blockade (ICB) therapy. Here, by establishing a screening strategy with a combination of tissue microarray (TMA), IHC staining, and measurement of circulating sEV PD-L1, we found that the endosomal sorting complex required for transport (ESCRT) member protein hepatocyte growth factor-regulated tyrosine kinase substrate (HRS) was the key regulator of circulating sEV PD-L1 in head and neck squamous cell carcinoma (HNSCC) patients. Increased HRS expression was found in tumor tissues and positively correlated with elevated circulating sEV PD-L1 in patients with HNSCC. The expression of HRS was also negatively correlated to the infiltration of CD8+ T cells. Knockdown of HRS markedly reduced PD-L1 expression in HNSCC cell-derived sEVs, and these sEVs from HRS knockdown cells showed decreased immunosuppressive effects on CD8+ T cells. Knockout of HRS inhibited tumor growth in immunocompetent mice together with PD-1 blockade. Moreover, a higher HRS expression was associated with a lower response rate to anti-PD-1 therapy in patients with HNSCC. In summary, our study reveals HRS, the core component of ESCRT-0, regulates sEV PD-L1 secretion, and is associated with the response to ICB therapy in patients with HNSCC, suggesting HRS is a promising target to improve cancer immunotherapy.

A long-term evaluation of periodontal phenotypes before and after the periodontal-orthodontic-orthognathic combined treatment of lower anterior teeth in patients with skeletal Angle class Ⅲ malocclusion / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the changes of periodontal phenotype (width of keratinized gingiva, thickness and height of alveolar bone) of lower anterior teeth in patients with skeletal class Ⅲ malocclusion before and after the periodontal-orthodontic-orthognathic combined treatment.@*METHODS@#In the study, 20 patients with skeletal class Ⅲ malocclusion (6 males and 14 females) completed the periodontal-orthodontic-orthognathic combined treatment were included from March 2017 to June 2022, with 39 central incisors, 40 lateral incisors and 40 canines. The mean age was (25.40±4.27) years (20-34 years). The mean follow-up time was (3.70±1.05) years from the beginning of periodontal corticotomy regenerative surgery (PCRS) to the end of the combined treatment. Cone-beam computed tomography (CBCT) was used to measure the thickness, area and height of alveolar bone by the same researcher, taken before the PCRS (T0), 6 months after the PCRS (T1), 12 months after the PCRS (T2), before the orthognathic surgery (T3), and after the periodontal-orthodontic-orthognathic combined treatment (T4). The periodontal clinical parameters were used to evaluate changes in the soft tissue by another researcher, measured before the PCRS (T0) and after the combined treatment (T4). Changes of soft and hard tissue were evaluated by the periodontal phenotype.@*RESULTS@#The width of keratinized gingiva increased significantly (all P < 0.001) in lower anterior teeth, the central incisors, lateral incisors and canines increased by (1.82±1.57) mm, (2.03±1.48) mm and (2.05±1.27) mm, respectively. The proportion of thick periodontal biotype in the central and lateral incisors increased significantly (all P < 0.001), while the changes of periodontal biotypes in the lower canines were not obvious. The thickness of labial alveolar bone of lower anterior teeth all increased significantly after periodontal corticotomy regenerative surgery and the combined treatment (all P < 0.001). The area of labial alveolar bone of lower anterior teeth also increased significantly after the combined treatment (all P < 0.001). The whole area of labial and lingual alveolar bone of central and lateral incisors increased (P < 0.001), while the whole area of canines remained the same. All The height of the alveolar bone increased (all P < 0.001) on the labial side after the treatment.@*CONCLUSION@#The periodontal phenotypes of lower anterior teeth were significantly improved after the periodontal-orthodontic-orthognathic combined treatment in patients with skeletal Angle class Ⅲ malocclusion. The improvement was long-termly stable, and the periodontal risk was reduced.

5-Demethoxy-10'-ethoxyexotimarin F, a New Coumarin with MAO-B Inhibitory Potential from Murraya exotica L.

Rutaceae plants are known for being a rich source of coumarins. Preliminary molecular docking showed that there was no significant difference for coumarins in Clausena and Murraya, both of which had high scoring values and showed good potential inhibitory activity to the MAO-B enzyme. Overall, 32 coumarins were isolated from Murraya exotica L., including a new coumarin 5-demethoxy-10'-ethoxyexotimarin F (1). Their structures were elucidated on the basis of a comprehensive analysis of 1D and 2D NMR and HRMS spectroscopic data, and the absolute configurations were assigned via a comparison of the specific rotations and the ECD exciton coupling method. The potential of new coumarin (1) as a selective inhibitor of MAO-B was initially evaluated through molecular docking and pharmacophore studies. Compound (1) showed selectivity for the MAO-B isoenzyme and inhibitory activity in the sub-micromolar range with an IC50 value of 153.25 ± 1.58 nM (MAO-B selectivity index > 172).

A histological study of vascular wall resident stem cells in venous malformations.

Vascular wall resident stem cells (VW-SCs) play a key role in vascular formation and remodeling under both physiological and pathological situations. They not only serve as a reservoir to supply all types of vascular cells needed, but also regulate vascular homeostasis by paracrine effects. Venous malformations (VMs) are common congenital vascular malformations which are just characterized by the deficient quantity and abnormal function of vascular cells. However, the existence and role of VW-SCs in VMs is still unclear at present. In this study, the level and distribution of VW-SCs in 22 specimens of VMs were measured by immunochemistry, double-labeling immunofluorescence, and qPCR, followed by the Spearman rank correlation test. We found that both the protein and mRNA expression levels of CD34, vWF, VEGFR2, CD44, CD90, and CD105 were significantly downregulated in VMs compared with that in normal venules. VW-SCs were sporadically distributed or even absent within and outside the endothelium of VMs. The expression of the VW-SC-related markers was positively correlated with the density of both endothelial cells and perivascular cells. All those results and established evidence indicated that VW-SCs were more sporadically distributed with fewer amounts in VMs, which possibly contributing to the deficiency of vascular cells in VMs.

Endothelial cells induce degradation of ECM through enhanced secretion of MMP14 carried on extracellular vesicles in venous malformation.

Venous malformations (VMs), featuring localized dilated veins, are the most common developmental vascular anomalies. Aberrantly organized perivascular extracellular matrix (ECM) is one of the prominent pathological hallmarks of VMs, accounting for vascular dysfunction. Although previous studies have revealed various proteins involved in ECM remodeling, the detailed pattern and molecular mechanisms underlying the endothelium-ECM interplay have not been fully elucidated. Our previous studies revealed drastically elevated extracellular vesicle (EV) secretion in VM lesions. Here, we identified increased EV-carried MMP14 in lesion fluids of VMs and culture medium of TIE2-L914F mutant endothelial cells (ECs), along with stronger ECM degradation. Knockdown of RAB27A, a required regulator for vesicle docking and fusion, led to decreased secretion of EV-carried MMP14 in vitro. Histochemical analysis further demonstrated a highly positive correlation between RAB27A in the endothelium and MMP14 in the perivascular environment. Therefore, our results proved that RAB27A-regulated secretion of EV-MMP14, as a new pattern of endothelium-ECM interplay, contributed to the development of VMs by promoting ECM degradation.

Protective Effects of Ferulic Acid on Metabolic Syndrome: A Comprehensive Review.

Metabolic syndrome (MetS) is a complex disease in which protein, fat, carbohydrates and other substances are metabolized in a disorderly way. Ferulic acid (FA) is a phenolic acid found in many vegetables, fruits, cereals and Chinese herbs that has a strong effect on ameliorating MetS. However, no review has summarized the mechanisms of FA in treating MetS. This review collected articles related to the effects of FA on ameliorating the common symptoms of MetS, such as diabetes, hyperlipidemia, hypertension and obesity, from different sources involving Web of Science, PubMed and Google Scholar, etc. This review summarizes the potential mechanisms of FA in improving various metabolic disorders according to the collected articles. FA ameliorates diabetes via the inhibition of the expressions of PEPCK, G6Pase and GP, the upregulation of the expressions of GK and GS, and the activation of the PI3K/Akt/GLUT4 signaling pathway. The decrease of blood pressure is related to the endothelial function of the aortas and RAAS. The improvement of the lipid spectrum is mediated via the suppression of the HMG-Co A reductase, by promoting the ACSL1 expression and by the regulation of the factors associated with lipid metabolism. Furthermore, FA inhibits obesity by upregulating the MEK/ERK pathway, the MAPK pathway and the AMPK signaling pathway and by inhibiting SREBP-1 expression. This review can be helpful for the development of FA as an appreciable agent for MetS treatment.

Improvement effects of Dianxianqing granule on blood-brain barrier injury in Alzheimer ’s disease model mice / 中国药房

OBJECTIVE To study the impr ovement effects of Dianxianqing granule on blood-brain barrier （BBB）injury in Alzheimer’s disease （AD）model mice by regulating NLR family pyrin domain containing 3（NLRP3）inflammasome signaling pathway. METHODS Totally 125 mice were randomly divided into sham operation group （n＝25）and modeling group （n＝100） by body weight. AD model was induced by intracerebroventricular injection of β-amyloid 25-35 in model group. Sham operation group was given normal saline with same method. The 100 model mice were randomly divided into model group ，Donepezil hydrochloride tablets group （positive control 1，1.3 mg/kg，i.g.），MCC950 group [positive control 2（selective NLRP 3 inhibitor），10 mg/kg，i.p.] and Dianxianqing granule group （12.48 g/kg by crude drug ，i.g.）by body weight ，with 25 mice in each group. Second day after modeling ，administration groups were given relevant medicine ，once a day ，for consecutive 21 d. Sham operation group and model group were given intragastric administration of water and intraperitoneal injection of normal saline. At last administration，the learning and memory ability was determined by Y maze test ，and blood-brain barrier permeability was measured by Evans blue leakage assay. The expressions of NLRP 3，anti-ionized calcium-binding adapter molecule 1（IBA-1），nuclear factor kappa B （NF-κB）p65，p53 upregulated modulator of apoptosis （PUMA），occludin（ocln），zonula occluden- 1（ZO-1）and claudin-5 （cldn5） in cerebral tissue were determined. RESULTS Compared with model group ， spontaneous alternate response rate ，protein expressions of ocln ，cldn5 lnzyxyqy2003@163.com and ZO- 1 in cerebral tissue were increased significantly in administration groups （P＜0.05 or P＜0.01）；Evans blue E-mail：jiadg2003@126.com content and protein expressions of NLRP 3，IBA-1，PUMA and NF-κB p65 in cerebral tissue were decreased significantly （P＜0.05 or P＜0.01）. CONCLUSIONS Dianxianqing granule can improve BBB injury of AD model m ice by inhibiting NLRP 3 inflammasome signaling pathway.

Effect of Micro-fertilizer Containing Rare Earth on Growth，Yield and Quality of Angelica sinensis / 中国实验方剂学杂志

ObjectiveTo investigate the effects of micro-fertilizer containing rare earth of different types and concentrations on the growth，yield and quality of Angelica sinensis. MethodOn the basis of the single-factor randomized block design， the growth and index components of Angelica sinensis were determined with rare earth-containing nitrate and chloride micro-fertilizers of different concentrations as foliar fertilizers. ResultSpraying 0.8 g·mL-1 rare earth-containing chloride micro-fertilizer could increase the economic yield of A. sinensis， with the fresh yield per mu （1 mu≈667 m2） reaching 855.4 kg and the dry yield per mu 350.7 kg，which increased by 15.16% and 28.70% respectively compared with that in the control group CK1. Spraying 1.2 g·mL-1 rare earth-containing nitrate micro-fertilizer could promote the growth and development of A. sinensis and significantly increase the content of index components， with the plant height reaching 93.05 cm，the stem diameter 15.60 mm，the root diameter 16.10 mm，the main root length 36.5 cm，and the number of leaves 11.25 pieces per plant， which increased by 32.76%，31.98%，41.98%，53.36%，and 45.16%， respectively， compared with those in the control group CK2. Besides， the content of ferulic acid，volatile oil，ligustilide， and extract was 0.96%，0.41%，0.30% and 48.76%，respectively，which increased by 12.94%，17.14%，11.11%， and 12.07%，respectively，compared with that in the control group CK2. ConclusionSpraying 0.8 g·mL-1 rare earth-containing chloride micro-fertilizer and 1.2 g·mL-1 rare earth-containing nitrate micro-fertilizer can promote the growth and development of A. sinensis，improve the medicinal properties，and increase yield and quality. Rare earth-containing micro-fertilizers can be applied in the standardization of A. sinensis cultivation， which can change the production status of A. sinensis that depends on chemical fertilizers and single fertilization， and promote the green， organic and ecological cultivation of A. sinensis.

In Situ Membrane Biotinylation Enables the Direct Labeling and Accurate Kinetic Analysis of Small Extracellular Vesicles in Circulation.

Circulating small extracellular vesicles (sEVs) are naturally occurring nanosized membrane vesicles that convey bioactive molecules between cells. Conventionally, to evaluate their behaviors in vivo, circulating sEVs have to be isolated from the bloodstream, then labeled with imaging materials in vitro, and finally injected back into the circulation of animals for subsequent detection. The tedious isolation-labeling-reinfusion procedures might have an undesirable influence on the natural properties of circulating sEVs, thereby changing their behaviors and the detected kinetics in vivo. Herein, we proposed an in situ biotinylation strategy to directly label circulating sEVs with intravenously injected DSPE-PEG-Biotin, aiming to evaluate the in vivo kinetics of circulating sEVs more biofriendly and accurately. Such an analysis strategy is free of isolation-labeling-reinfusion procedures and has no unfavorable influence on the natural behaviors of sEVs. The results showed that the lifetime of generic circulating sEVs in mice was around 3 days. Furthermore, we, for the first time, revealed the distinct in vivo kinetics of circulating sEV subpopulations with different cell sources, among which erythrocyte-derived sEVs showed the longest lifespan. Moreover, compared with circulating sEVs in situ or used as autograft, circulating sEVs used as allograft had the shortest lifetime. In addition, the in situ biotinylation strategy also provides a way for the enrichment of biotinylated circulating sEVs. In summary, this study provides a novel strategy for in situ labeling of circulating sEVs, which would facilitate the accurate characterization of their kinetics in vivo, thereby accelerating their future application as biomarkers and theranositic vectors.