Rapid assembly of PMMA microfluidic devices with PETE membranes for studying the endothelium

Biomicrofluidic devices and organ-on-a-chip (OOC) systems with integrated membranes are often fabricated from two different thermoplastic materials but bonding of such dissimilar thermoplastics remains challenging to manufacture at scale. Here, we present a method to bond poly(methylmethacrylate) layers to a polyethylene terephthalate porous membrane to create membrane-based microfluidic devices for biological barrier modeling. By combining milling, laser cutting and chlorocarbon-based solvent bonding supported by retention grooves, we achieved a fabrication rate of 36 devices in 5 h. Chlorocarbon-based solvent bonding resulted in bond strength of ~10 J/m2 and did not adversely affect the membrane pore structure or the channel cross-sectional shape. The bonded devices were found to support long term culture of human endothelial cells that developed expected morphology and cell-cell adhesion contacts as evidenced by immunofluorescent labeling of VE-cadherin. Barrier permeability was measured to be 3.38 × 106 cm/s for 10 kDa dextran using a sampling-based method compatible with mass spectrometry and scintillation techniques and was in agreement with literature. To validate the devices for cell migration experiments, THP-1 monocytes were introduced into devices with confluent endothelial monolayers. Monocytes adhered to and migrated through the endothelium. Activation of the endothelium with TNF-α prior to introducing monocytes significantly increased monocyte adhesion. Overall, the rapid device fabrication method achieved medium-volume production rates and was found to support both cell culture and experiments associated with measuring barrier and endothelial function. This fabrication method has potential to both accelerate biomicrofluidics and OOC research in the lab and accelerate development of commercialized microfluidic membrane devices

Discovery and fine-mapping of height loci via high-density imputation of GWASs in individuals of African ancestry

Although many loci have been associated with height in European ancestry populations, very few have been identified in African ancestry individuals. Furthermore, many of the known loci have yet to be generalized to and fine-mapped within a large-scale African ancestry sample. We performed sex-combined and sex-stratified meta-analyses in up to 52,764 individuals with height and genome-wide genotyping data from the African Ancestry Anthropometry Genetics Consortium (AAAGC). We additionally combined our African ancestry meta-analysis results with published European genome-wide association study (GWAS) data. In the African ancestry analyses, we identified three novel loci (SLC4A3, NCOA2, ECD/FAM149B1) in sex-combined results and two loci (CRB1, KLF6) in women only. In the African plus European sex-combined GWAS, we identified an additional three novel loci (RCCD1, G6PC3, CEP95) which were equally driven by AAAGC and European results. Among 39 genome-wide significant signals at known loci, conditioning index SNPs from European studies identified 20 secondary signals. Two of the 20 new secondary signals and none of the 8 novel loci had minor allele frequencies (MAF) \u3c 5%. Of 802 known European height signals, 643 displayed directionally consistent associations with height, of which 205 were nominally significant (p \u3c 0.05) in the African ancestry sex-combined sample. Furthermore, 148 of 241 loci contained ≤20 variants in the credible sets that jointly account for 99% of the posterior probability of driving the associations. In summary, trans-ethnic meta-analyses revealed novel signals and further improved fine-mapping of putative causal variants in loci shared between African and European ancestry populations