Technological advancements in research on circulating biomarkers from patient derived blood have enabled a less invasive means of diagnosing non-hematologic cancers. Considered a more practical way of real-time patient monitoring than traditional tumor biopsy, liquid biopsy markers including circulating tumor cells (CTCs), circulating tumor DNA (ctDNA) and extracellular vesicles (EVs) and exosomes certainly have the potential to change the dynamics of cancer management and treatment. Liquid biopsy essentially presents a snapshot of the disease from the primary and/or distant tumor locations and can be utilized for repeated sampling of tumor markers to adjust therapy according to the patient's response to treatment, also known as personalized or precision treatment. In this review, we discuss the research progress in this field with respect to each of the liquid biopsy markers ranging from CTCs, EVs to ctDNA. First, we highlight key CTC technologies that have been commercialized and extensively employed for patient sample analysis. Next, we present some recent developments with regards to exosome and ctDNA research. We then conclude with some future perspectives on the areas of research for these biomarkers. Taken together, we believe these non-invasive capabilities and their potential for diagnostic development can influence treatment selections and aid precision cancer therapies.

The physical microenvironment of cells plays a fundamental role in regulating cellular behavior and cell fate, especially in the context of cancer metastasis. For example, capillary deformation can destroy arrested circulating tumor cells while the dense extracellular matrix can form a physical barrier for invading cancer cells. Understanding how metastatic cancer cells overcome the challenges brought forth by physical confinement can help in developing better therapeutics that can put a stop to this migratory stage of the metastatic cascade. Numerous in vivo and in vitro assays have been developed to recapitulate the metastatic processes and study cancer cell migration in a confining microenvironment. In this review, we summarize some of the representative techniques and the exciting new findings. We critically review the advantages, as well as challenges associated with these tools and methodologies, and provide a guide on the applications that they are most suited for. We hope future efforts that push forward our current understanding on metastasis under confinement can lead to novel and more effective diagnostic and therapeutic strategies against this dreaded disease.

Cancer-derived extracellular vesicles (EVs) have been demonstrated to be implicated in various processes of cancer development, with most of the EV-induced changes attributed to EV-proteins and EV-microRNAs. However, the knowledge about the abundance of cancer EV-mRNAs and their contribution to cancer development remain elusive. Here, we show that mRNAs prevail in cancer EVs as compared with normal EVs, and cancer EVs that carry abundant angiogenic mRNAs activate angiogenesis in human umbilical vein endothelial cells (HUVECs). Specifically, of a gene panel comprising 61 hypoxia-targeted oncogenes, a larger proportion is harbored by cancer EVs (>40%) than normal EVs (14.8%). Fluorescent trafficking indicates cancer EVs deliver translatable mRNAs such as VEGFA to HUVECs, contributing to the activation of VEGFR-dependent angiogenesis and the upregulation of epithelial-mesenchymal transition-related and metabolism-related genes. Overall, our findings provide novel insights into EV-mRNAs and their role in angiogenesis, and has potential for diagnostic and therapeutic applications.

Under internal or external insults such as aging and oxidative stresses, cells are induced into a senescent state and stop cellular division permanently. As senescent cells (SnCs) accumulate, the regeneration capacity of biological tissue would be compromised, which has been found to be associated with a plethora of age-related disorders. Therefore, isolating SnCs becomes necessary. To address the lack of effective surface markers for SnCs isolation, a label-free microfluidic device was proposed in this paper, in which a spiral microchannel was deployed to isolate SnCs based on their size differences. We adopted a well-received cellular senescence model by exerting excessive oxidative stress to murine mesenchymal stem cells. This model was then validated through a series of SnCs characterizations including size measurement, p16INK4a expression level, senescence-associated beta-galactosidase, and doubling time. The senescence chip demonstrated an efficiency of 75% and viability over 85% at a flow rate of 5 ml/min. The average cell size from the inner outlet was 5 μm larger than that from the outer outlet. The isolated cells had a sixfold higher p16INK4a expression level. Overall, the chip had an area under curve of 0.719 in the receiver operating characteristic analysis, showing decent performance in sorting SnCs. By having the ability to perform size-based sorting at a high flow rate, such a microfluidic device can provide high-throughput and label-free isolation of SnCs. To further improve the isolation performance, the device can be modified to introduce additional physical biomarkers of SnCs such as stiffness. This device poses a good potential in purification for cytotherapy or estimation of biological age.

Hydroxyapatite (HA) is a commonly used biomaterial for bone grafting. Unfortunately, the lack of carbonate ions in normal HA limits its osseointegration ability. Alternatively, carbonate-substituted hydroxyapatite (CHA) was reported to be a better bone substitution because it has almost the same chemical composition and structure as natural bone minerals. In this study, a novel method was proposed to directly synthesize CHA through one-step hydrothermal exchange from seashells. The morphology and the amount of carbonate-substitution of the fabricated CHA can be well controlled by adjusting the PH during the reaction: with the increasing of PH, the morphology of the final product was transferred from long needle-like to sheet-like and the amount of CO32 substitution increased gradually. The bioactivity of the products was evaluated by CKK-8 assay. It was found that the CHA significantly improved bioactivity compared to the control group, and the needle-like CHA had a better bioactivity than that of the sheet-like CHA.