William Shi

Nanoparticle biointerfacing by platelet membrane cloaking

Development of functional nanoparticles can be encumbered by unanticipated material properties and biological events, which can affect nanoparticle effectiveness in complex, physiologically relevant systems. Despite the advances in bottom-up nanoengineering and surface chemistry, reductionist functionalization approaches remain inadequate in replicating the complex interfaces present in nature and cannot avoid exposure of foreign materials. Here we report on the preparation of polymeric nanoparticles enclosed in the plasma membrane of human platelets, which are a unique population of cellular fragments that adhere to a variety of disease-relevant substrates. The resulting nanoparticles possess a right-side-out unilamellar membrane coating functionalized with immunomodulatory and adhesion antigens associated with platelets. Compared to uncoated particles, the platelet membrane-cloaked nanoparticles have reduced cellular uptake by macrophage-like cells and lack particle-induced complement activation in autologous human plasma. The cloaked nanoparticles also display platelet-mimicking properties such as selective adhesion to damaged human and rodent vasculatures as well as enhanced binding to platelet-adhering pathogens. In an experimental rat model of coronary restenosis and a mouse model of systemic bacterial infection, docetaxel and vancomycin, respectively, show enhanced therapeutic efficacy when delivered by the platelet-mimetic nanoparticles. The multifaceted biointerfacing enabled by the platelet membrane cloaking method provides a new approach in developing functional nanoparticles for disease-targeted delivery.

Lens regeneration using endogenous stem cells with gain of visual function

The repair and regeneration of tissues using endogenous stem cells represents an ultimate goal in regenerative medicine. To our knowledge, human lens regeneration has not yet been demonstrated. Currently, the only treatment for cataracts, the leading cause of blindness worldwide, is to extract the cataractous lens and implant an artificial intraocular lens. However, this procedure poses notable risks of complications. Here we isolate lens epithelial stem/progenitor cells (LECs) in mammals and show that Pax6 and Bmi1 are required for LEC renewal. We design a surgical method of cataract removal that preserves endogenous LECs and achieves functional lens regeneration in rabbits and macaques, as well as in human infants with cataracts. Our method differs conceptually from current practice, as it preserves endogenous LECs and their natural environment maximally, and regenerates lenses with visual function. Our approach demonstrates a novel treatment strategy for cataracts and provides a new paradigm for tissue regeneration using endogenous stem cells.

DNA methylation markers for diagnosis and prognosis of common cancers

Significance The ability to identify a specific cancer using minimally invasive biopsy holds great promise for improving diagnosis and prognosis. We evaluated the utility of DNA methylation profiles for differentiating tumors and normal tissues for four common cancers (lung, breast, colon, and liver) and found that they could differentiate cancerous tissue from normal tissue with >95% accuracy. This signature also correctly identified 19 of 20 breast cancer metastases and 29 of 30 colorectal cancer metastases to the liver. We report that methylation patterns can predict the prognosis and survival, with good correlation between differential methylation of CpG sites and expression of cancer-associated genes. Their findings demonstrate the utility of methylation biomarkers for the molecular characterization, diagnosis, and prognosis of cancer. The ability to identify a specific cancer using minimally invasive biopsy holds great promise for improving the diagnosis, treatment selection, and prediction of prognosis in cancer. Using whole-genome methylation data from The Cancer Genome Atlas (TCGA) and machine learning methods, we evaluated the utility of DNA methylation for differentiating tumor tissue and normal tissue for four common cancers (breast, colon, liver, and lung). We identified cancer markers in a training cohort of 1,619 tumor samples and 173 matched adjacent normal tissue samples. We replicated our findings in a separate TCGA cohort of 791 tumor samples and 93 matched adjacent normal tissue samples, as well as an independent Chinese cohort of 394 tumor samples and 324 matched adjacent normal tissue samples. The DNA methylation analysis could predict cancer versus normal tissue with more than 95% accuracy in these three cohorts, demonstrating accuracy comparable to typical diagnostic methods. This analysis also correctly identified 29 of 30 colorectal cancer metastases to the liver and 32 of 34 colorectal cancer metastases to the lung. We also found that methylation patterns can predict prognosis and survival. We correlated differential methylation of CpG sites predictive of cancer with expression of associated genes known to be important in cancer biology, showing decreased expression with increased methylation, as expected. We verified gene expression profiles in a mouse model of hepatocellular carcinoma. Taken together, these findings demonstrate the utility of methylation biomarkers for the molecular characterization of cancer, with implications for diagnosis and prognosis.

Copy Number Variations with Isolated Fetal Ventriculomegaly.

BACKGROUND Copy Number Variations (CNVs) are an important genetic cause of a number of neurodevelopmental disorders (NDs). However, the association between CNVs and the development and prognosis of fetal isolated mild ventriculomegaly (IMV) is unclear. OBJECTIVES To investigate possible associations between CNVs and the development of fetal IMV. METHODS This retrospective study recruited 154 subjects with ultrasound-confirmed fetal IMV and 190 subjects in a control cohort who underwent a high-risk prenatal serum screening program. The exclusion criteria included fetus G-banding chromosomal abnormality or positive fetus TORCH infection. DNA samples from all 344 fetuses were examined by an SNP-array. Developmental outcomes were assessed during postnatal follow-up. RESULTS Fourteen pathogenic CNVs (pCNVs) were identified in 13 out of 154 IMV fetuses. Three pCNVs were found in 3 out of 190 subjects in the prenatal screening high-risk cohort, with a significant difference (P value=0.016, X2 test). Notably, the 14 pCNVs detected in the IMV cohort were all associated with neurodevelopmental disorders (NDs), including autism, intellectual disability. Among the 13 IMV fetuses carrying pCNVs, five subjects were found in the postnatal follow-up to manifest NDs, including two with autism and three with mild neurodevelopmental delay. The other 8 subjects consisted of three normal infants younger than 12-months old, two lost in the follow-up, and three with the termination of pregnancy. Out of 141 IMV subjects without detectable pCNVs, 123 subjects showed normal development, 16 were lost in the follow-up, 2 subjects terminated the pregnancy due to fetal hydrocephalus or congenital heart disease in the late fetus development. CONCLUSIONS This study suggests an association between pCNVs and fetal IMV. pCNVs may be involved in the pathological process of fetal IMV and postnatal NDs. Identifying specific genomic alterations may provide an insight into pathogenetic mechanism and aid better diagnosis and prognosis of neurodevelopmental outcomes in fetal IMV.

Joint Antiangiogenic Effect of ATN-161 and Anti-VEGF Antibody in a Rat Model of Early Wet Age-Related Macular Degeneration

The wet form of age-related macular degeneration (AMD) is a leading cause of blindness among elderly Americans and is characterized by abnormal vessel growth, termed choroidal neovascularization (CNV). Integrin α5β1 is a transmembrane receptor that binds matrix macromolecules and proteinases to stimulate angiogenesis. We recently demonstrated that integrin α5β1 plays a critical role in the development of choroidal neovascularization. In this study, we determined the role and underlying mechanisms of integrin α5β1 in angiogenesis in human choroidal endothelial cells and evaluated the antiangiogenic effects of delivering a combination therapy of ATN-161, an integrin α5β1 inhibitor, and an anti-VEGF monoclonal antibody to rats with laser-induced CNV. Vascular endothelial growth factor (VEGF) is a signaling protein that stimulates vasculogenesis and angiogenesis through a pathway that is distinct from the integrin α5β1 signaling pathway. Our results indicate that fibronectin binds to integrin α5β1 and synergizes VEGF-induced angiogenesis via two independent signaling pathways, FN/integrin α5β1/FAK/ERK1/2 and FN/integrin α5β1/FAK/AKT. Integrin α5 knockdown by shRNA inhibits endothelial cell migration, tube formation, and proliferation, while ATN-161 only partially decreases integrin α5 function. Treatment with ATN-161 combined with anti-VEGF antibody showed joint effects in attenuating angiogenesis. In summary, our results provide the first evidence for the mechanisms by which integrin α5β1 is involved in ocular pathological neovascularization in vivo, suggesting that dual inhibition of integrin α5β1 and VEGF may be a promising novel therapeutic strategy for CNV in wet AMD.

Predictors of radiation exposure to providers during percutaneous nephrolithotomy

Background: Limited studies have reported on radiation risks of increased ionizing radiation exposure to medical personnel in the urologic community. Fluoroscopy is readily used in many urologic surgical procedures. The aim of this study was to determine radiation exposure to all operating room personnel during percutaneous nephrolithotomy (PNL), commonly performed for large renal or complex stones. Materials and Methods: We prospectively collected personnel exposure data for all PNL cases at two academic institutions. This was collected using the Instadose™ dosimeter and reported both continuously and categorically as high and low dose using a 10 mrem dose threshold, the approximate amount of radiation received from one single chest X-ray. Predictors of increased radiation exposure were determined using multivariate analysis. Results: A total of 91 PNL cases in 66 patients were reviewed. Median surgery duration and fluoroscopy time were 142 (38–368) min and 263 (19–1809) sec, respectively. Median attending urologist, urology resident, anesthesia, and nurse radiation exposure per case was 4 (0–111), 4 (0–21), 0 (0–5), and 0 (0–5) mrem, respectively. On univariate analysis, stone area, partial or staghorn calculi, surgery duration, and fluoroscopy time were associated with high attending urologist and resident radiation exposure. Preexisting access that was utilized was negatively associated with resident radiation exposure. However, on multivariate analysis, only fluoroscopy duration remained significant for attending urologist radiation exposure. Conclusion: Increased stone burden, partial or staghorn calculi, surgery and fluoroscopy duration, and absence of preexisting access were associated with high provider radiation exposure. Radiation safety awareness is essential to minimize exposure and to protect the patient and all providers from potential radiation injury.

Corrigendum: Lens regeneration using endogenous stem cells with gain of visual function

This corrects the article DOI: 10.1038/nature17181

Optimization of urinary dipstick pH: Are multiple dipstick pH readings reliably comparable to commercial 24-hour urinary pH?

Purpose Accurate measurement of pH is necessary to guide medical management of nephrolithiasis. Urinary dipsticks offer a convenient method to measure pH, but prior studies have only assessed the accuracy of a single, spot dipstick. Given the known diurnal variation in pH, a single dipstick pH is unlikely to reflect the average daily urinary pH. Our goal was to determine whether multiple dipstick pH readings would be reliably comparable to pH from a 24-hour urine analysis. Materials and Methods Kidney stone patients undergoing a 24-hour urine collection were enrolled and took images of dipsticks from their first 3 voids concurrently with the 24-hour collection. Images were sent to and read by a study investigator. The individual and mean pH from the dipsticks were compared to the 24-hour urine pH and considered to be accurate if the dipstick readings were within 0.5 of the 24-hour urine pH. The Bland-Altman test of agreement was used to further compare dipstick pH relative to 24-hour urine pH. Results Fifty-nine percent of patients had mean urinary pH values within 0.5 pH units of their 24-hour urine pH. Bland-Altman analysis showed a mean difference between dipstick pH and 24-hour urine pH of -0.22, with an upper limit of agreement of 1.02 (95% confidence interval [CI], 0.45–1.59) and a lower limit of agreement of -1.47 (95% CI, -2.04 to -0.90). Conclusions We concluded that urinary dipstick based pH measurement lacks the precision required to guide medical management of nephrolithiasis and physicians should use 24-hour urine analysis to base their metabolic therapy.

Genetic and environmental factors strongly influence risk, severity and progression of age-related macular degeneration

[This corrects the article DOI: 10.1038/sigtrans.2016.16.].