Heterogeneity of Circulating Tumor Cell Neoplastic Subpopulations Outlined by Single-Cell Transcriptomics.

Fatal metastasis occurs when circulating tumor cells (CTCs) disperse through the blood to initiate a new tumor at specific sites distant from the primary tumor. CTCs have been classically defined as nucleated cells positive for epithelial cell adhesion molecule and select cytokeratins (EpCAM/CK/DAPI), while negative for the common lymphocyte marker CD45. The enumeration of CTCs allows an estimation of the overall metastatic burden in breast cancer patients, but challenges regarding CTC heterogeneity and metastatic propensities persist, and their decryption could improve therapies. CTCs from metastatic breast cancer (mBC) patients were captured using the RareCyteTM Cytefinder II platform. The Lin- and Lin+ (CD45+) cell populations isolated from the blood of three of these mBC patients were analyzed by single-cell transcriptomic methods, which identified a variety of immune cell populations and a cluster of cells with a distinct gene expression signature, which includes both cells expressing EpCAM/CK ("classic" CTCs) and cells possessing an array of genes not previously associated with CTCs. This study put forward notions that the identification of these genes and their interactions will promote novel areas of analysis by dissecting properties underlying CTC survival, proliferation, and interaction with circulatory immune cells. It improves upon capabilities to measure and interfere with CTCs for impactful therapeutic interventions.

Mechanical, Cellular, and Proteomic Properties of Laryngotracheal Cartilage.

The larynx sometimes requires repair and reconstruction due to cancer resection, trauma, stenosis, or developmental disruptions. Bioengineering has provided some scaffolding materials and initial attempts at tissue engineering, especially of the trachea, have been made. The critical issues of providing protection, maintaining a patent airway, and controlling swallowing and phonation, require that the regenerated laryngotracheal cartilages must have mechanical and material properties that closely mimic native tissue. These properties are determined by the cellular and proteomic characteristics of these tissues. However, little is known of these properties for these specific cartilages. This review considers what is known and what issues need to be addressed.

The role of SDF-1α-ECM crosstalk in determining neural stem cell fate.

The consequences of central nervous system injury are far-reaching and debilitating and, while an endogenous repair response to neural injury has been observed in recent years, the mechanisms behind this response remain unclear. Neural progenitor/stem cell (NPSC) migration to the site of injury from the neural stem cell niches (e.g. subventricular zone and hippocampus) has been observed to be vasophilic in nature. While the chemotactic stimuli directing NPSC homing to injury is not well established, it is thought to be due in part to an increasing gradient of chemotactic cytokines, such as stromal cell-derived factor 1α (SDF-1α). Based on these recent findings, we hypothesize that critical crosstalk between SDF-1α and the extracellular matrix (ECM) drives injury-induced NPSC behavior. In this study, we investigated the effect of SDF-1α and ECM substrates (Matrigel, laminin, and vitronectin) on the migration, differentiation, and proliferation of NPSCs in vitro using standard assays. The results demonstrated that SDF-1α and laminin-based ECM (Matrigel and laminin) significantly and synergistically enhanced NPSC migration and acute neuronal differentiation. These effects were significantly attenuated with the addition of AMD3100 (an antagonist against the SDF-1α receptor, CXCR4). SDF-1α alone significantly increased NPSC proliferation regardless of ECM substrate, however no synergy was observed between SDF-1α and the ECM. These results serve to elucidate the relationship between adhesive and soluble signaling factors of interest and their effect on NPSC behavior following neural injury. Furthermore, these results better inform the next generation of biomaterials aimed at stimulating endogenous neural regeneration for neural injury and neurodegenerative diseases.

Temporal differences in Erk1/2 activity distinguish among combinations of extracellular matrix components.

Rational design of biomaterials requires understanding how cells interrogate their microenvironment. In this study, human umbilical vein endothelial cells are cultured on combinations of extracellular matrix (ECM) components (collagen I, collagen IV, vitronectin, fibronectin, laminin, heparan sulfate proteoglycan, chondroitin sulfate proteoglycan), and the phosphorylation of four intracellular signaling kinases (Erk1/2, JNK, Akt1, and NFκB) is quantified. These combinations of ECM components elicit different temporal patterns of Erk1/2 phosphorylation. Collagen I-containing substrates cause Erk1/2 phosphorylation to reach maximal levels at 30 min and remain near maximal levels until 90 min. Collagen IV/laminin substrates elicit maximal phosphorylation at 30-45 min, and then phosphorylation decreases substantially at 60-90 min. All other combinations studied (collagen IV and vitronectin-based combinations) cause an increase in phosphorylation at 30-45 min, but not to maximal levels; maximal phosphorylation is reached by 60-90 min. These temporal patterns of phosphorylation may explain how a limited number of intracellular signaling pathways can distinguish among thousands of possible combinations of microenvironmental cues by adding to the information contained in each cell signaling pathway.