Ex Vivo Dynamics of Human Glioblastoma Cells in a Microvasculature-on-a-Chip System Correlates with Tumor Heterogeneity and Subtypes

The brain tumor perivascular niche(PVN),the region in the vicinity of microvessels is a prime location for brain tumor stem-like cells(BTSCs)[1].Tumor microvasculature creates a complex microenvironment consisting of various cell types,the extracellular matrix,and soluble factors that mediate cell-cell interaction.The brain tumor PVN controls maintenance,expansion,and differentiation of BTSCs via direct cell contact or paracrine signaling cues.BTSCs often receive bidirectional crosstalk from endothelial cells and other cell types in the niche[2].In addition,the perivascular zone may serve as a path for tumor cells to migrate over long distances(3,4)Unlike other solid tumors,glioblastoma multiforme(GBM)cells rarely metastasize to other organs,but they can invade the entire brain by migrating along specific brain tissue structures,such as blood vessels or white matter tracts,leading to high rates of relapse.Despite the success in modeling diffuse brain tumors in both genetically-modified and patient-derived xenograft(PDX)animals,there is an unmet need for an in vitro system that can bridge conventional cell culture and animal models by mimicking not only the anatomy but also the function of the PVN to study the dynamics of BTSCs.In this presentation,I will describe the use of a microvasculature-on-a-chip system as a PVN model to evaluate the dynamics of BTSCs ex vivo from 10 glioblastoma patients [5].We observed that BTSCs preferentially localize in the perivascular zone.Live cell tracking showed that the cells residing in the vicinity of microvessels had the lowest motility,while a fraction of cells on the microvessels unexpectedly possessed the highest motility and migrated over the longest distance.These results indicate that the perivascular zone is a niche for BTSCs,while the microvascular tracks are also a path for long-distance tumor cell migration and invasion.Additionally,the degree of co-localization between tumor cells and microvessels varied significantly across patients.To validate the results from our microvasculature-on-a-chip system,we used single-cell transcriptome sequencing(10 patients and 21,750 single cells in total)to identify the subtype of each tumor cell.The co-localization coefficient was found to correlate positively with proneural(stem-like)or mesenchymal(invasive)but not classical(proliferative)tumor cells.Furthermore,we found that a gene signature profile including PDGFRA correlated strongly with the'homing'of brain tumor cells to the PVN.Our findings demonstrated that ex vivo dynamics of human brain tumor cells in a microvasculature-on-a-chip model can recapitulate in vivo tumor cell dynamics,heterogeneity,and subtypes,representing a new route to the study of human tumor cell biology and uncover patient-specific tumor cell functions.Acknowledgments:We thank Drs.Laura Niklason,Eric Holland,Franziska Michor,and Frank Szulzewsky for scientific discussion.We thank Misha Guy,Vladimir Polejaev,Zhenting Jiang,and Alice Yun for suggestions and help on the simulation computing and SEM/confocal imaging process.This research was supported by the Packard Fellowship for Science and Engineering(R.F.),National Science Foundation CAREER Award CBET-1351443(R.F.),U54 CA193461(R.F.),U54CA209992(Sub-Project ID:7297 to R.F.),R01 NS095817(J.Z.),Yale Cancer Center Co-Pilot Grant(to R.F.).The molds for microfluidic devices were fabricated in the Yale School of Engineering and Applied Science cleanroom.Sequencing was performed at the Yale Center for Genome Analysis(YCGA)facility.Data was analyzed at Yale High Performance Computing(HPC)center.Super resolution confocal imaging was performed at Yale Center for Cellular and Molecular Imaging(CCMI).

Single small molecule-assembled nanoparticles mediate efficient oral drug delivery

Oral drug delivery,which requires surviving the harsh environment in the gastrointestinal(Gl)tract and penetrating the intestinal epithelium,has not bee n achieved using simple formulatio n nan oparticles(NPs).Medici nal natural products(MNPs)have bee n widely used in traditi onal medicine for disease management through oral consumption.However,most pharmacologically active compounds within MNPs do not have the properties suitable for oral applicatio ns.We hypothesize that some MNPs contain n atural nano materials that can convert those compounds into oral formulations by forming NPs.After screening 66 MNPs,we identified five classes of small molecules that form NPs,many of which are capable of efficient drug encapsulation and Gl penetration.We show that one of them,dehydrotrametenolic acid(DTA),is capable of mediating oral delivery for effective disease treatment.We determined that DTA NPs assemble through hydrogen bonding and penetra怕the Gl tract via apical sodium-depe ndent bile acid tran sporter.Our study reveals a no vel class of single comp orient,small molecule-assembled NPs for oral drug delivery,and suggests a n ovel approach to modernizi ng MNPs through nano material discovery.

Brain-targeting,acid-responsive antioxidant nanoparticles for stroke treatment and drug delivery

Stroke is the leading cause of death and disability.Currently,there is no effective pharmacological treatment for this disease,which can be partially attributed to the inability to efficiently deliver therapeutics to the brain.Here we report the development of natural compound-derived nanoparticles(NPs),which function both as a potent therapeutic agent for stroke treatment and as an efficient carrier for drug delivery to the ischemic brain.First,we screened a collection of natural nanomaterials and identified betulinic acid(BA)as one of the most potent antioxidants for stroke treatment.Next,we engineered BA NPs for preferential drug release in acidic ischemic tissue through chemically converting BA to betulinic amine(BAM)and for targeted drug delivery through surface conjugation of AMD3100,a CXCR4 antagonist.The resulting AMD3100-conjugated BAM NPs,or A-BAM NPs,were then assessed as a therapeutic agent for stroke treatment and as a carrier for delivery of NA1,a neuroprotective peptide.We show that intravenous administration of A-BAM NPs effectively improved recovery from stroke and its efficacy was further enhanced when NA1 was encapsulated.Due to their multifunctionality and significant efficacy,we anticipate that A-BAM NPs have the potential to be translated both as a therapeutic agent and as a drug carrier to improve the treatment of stroke.