Hematology Commons^™

Investigating Clot-Flow Interactions By Integrating Intravital Imaging With In Silico Modeling For Analysis Of Flow, Transport, And Hemodynamic Forces, Chayut Teeraratkul, Maurizio Tomaiuolo, Timothy Stalker, Debanjan Mukherjee

Cardeza Foundation for Hematologic Research

As a blood clot forms, grows, deforms, and embolizes following a vascular injury, local clot-flow interactions lead to a highly dynamic flow environment. The local flow influences transport of biochemical species relevant for clotting, and determines the forces on the clot that in turn lead to clot deformation and embolization. Despite this central role, quantitative characterization of this dynamic clot-flow interaction and flow environment in the clot neighborhood remains a major challenge. Here, we propose an approach that integrates dynamic intravital imaging with computer geometric modeling and computational flow and transport modeling to develop a unified in silico framework to …

The Function Of Ask1 In Sepsis And Stress-Induced Disorders, John Kostyak, Steven Mckenzie, Ulhas Naik

Cardeza Foundation for Hematologic Research

Apoptosis signal-regulating kinase 1 (ASK1) is a serine-threonine kinase that is ubiquitously expressed in nucleated cells and is responsible for the activation of multiple mitogen-activated protein kinases (MAPK) to regulate cell stress. Activation of ASK1 via cellular stress leads to activation of downstream signaling components, activation of transcription factors, and proinflammatory cytokine production. ASK1 is also expressed in anucleate platelets and is a key player in platelet activation as it is important for signaling. Interestingly, the mechanism of ASK1 activation is cell type-dependent. In this review we will explore how ASK1 regulates a variety of cellular processes from innate immune …

Fluorescent Peptide For Detecting Factor Xiiia Activity And Fibrin In Whole Blood Clots Forming Under Flow, Yue Liu, Jennifer Crossen, Timothy J. Stalker, Scott L. Diamond

Cardeza Foundation for Hematologic Research

Background

During clotting, thrombin generates fibrin monomers and activates plasma-derived transglutaminase factor (F) XIIIa; collagen and thrombin-activated platelets offer thrombin-independent cellular FXIIIa (cFXIIIa) for clotting. Detecting fibrin on collagen and tissue factor surfaces in whole blood clotting typically uses complex reagents like fluorescent fibrinogen or antifibrin antibody.

Objectives

We want to test whether the peptide using the α2- antiplasmin crosslinking mechanism by FXIIIa is a useful tool in both monitoring FXIIIa activity, and visualize and monitor fibrin formation, deposition, and extent of crosslinking within fibrin structures in whole blood clots formed under flow.

Methods

We tested a fluorescent peptide derived …

Glutamate Receptor Dysregulation And Platelet Glutamate Dynamics In Alzheimer's And Parkinson's Diseases: Insights Into Current Medications, Deepa Gautam, Ulhas Naik, Meghna Naik, Santosh Yadav, Rameshwar Nath Chaurasia, Debabrata Dash

Cardeza Foundation for Hematologic Research

Two of the most prevalent neurodegenerative disorders (NDDs), Alzheimer's disease (AD) and Parkinson's disease (PD), present significant challenges to healthcare systems worldwide. While the etiologies of AD and PD differ, both diseases share commonalities in synaptic dysfunction, thereby focusing attention on the role of neurotransmitters. The possible functions that platelets may play in neurodegenerative illnesses including PD and AD are becoming more acknowledged. In AD, platelets have been investigated for their ability to generate amyloid-ß (Aß) peptides, contributing to the formation of neurotoxic plaques. Moreover, platelets are considered biomarkers for early AD diagnosis. In PD, platelets have been studied for …

Activation Of Coagulation And Proinflammatory Pathways In Thrombosis With Thrombocytopenia Syndrome And Following Covid-19 Vaccination, Malika Aid, Kathryn E. Stephenson, Ai-Ris Y. Collier, Joseph P. Nkolola, James V. Michael, Steven E. Mckenzie, Dan H. Barouch

Cardeza Foundation for Hematologic Research

Thrombosis with thrombocytopenia syndrome (TTS) is a rare but potentially severe adverse event following immunization with adenovirus vector-based COVID-19 vaccines such as Ad26.COV2.S (Janssen) and ChAdOx1 (AstraZeneca). However, no case of TTS has been reported in over 1.5 million individuals who received a second immunization with Ad26.COV2.S in the United States. Here we utilize transcriptomic and proteomic profiling to compare individuals who receive two doses of Ad26.COV2.S with those vaccinated with BNT162b2 or mRNA-1273. Initial Ad26.COV2.S vaccination induces transient activation of platelet and coagulation and innate immune pathways that resolve by day 7; by contrast, patients with TTS show robust …

Pet Imaging Of Microglia Using Pbr28suv Determines Therapeutic Efficacy Of Autologous Bone Marrow Mononuclear Cells Therapy In Traumatic Brain Injury, Supinder S Bedi, Michael C Scott, Max A Skibber, Akshita Kumar, Henry W Caplan, Hasen Xue, David Sequeira, Alison L Speer, Fanni Cardenas, Franciska Gudenkauf, Karen Uray, Amit K. Srivastava, Alan R Prossin, Charles S Cox

Cardeza Foundation for Hematologic Research

Traumatic brain injury (TBI) results in activated microglia. Activated microglia can be measured in vivo by using positron emission topography (PET) ligand peripheral benzodiazepine receptor standardized uptake values (PBR28suv). Cell based therapies have utilized autologous bone marrow mononuclear cells (BMMNCs) to attenuate activated microglia after TBI. This study aims to utilize in vivo PBR28suv to assess the efficacy of BMMNCs therapy after TBI. Seventy-two hours after CCI injury, BMMNCs were harvested from the tibia and injected via tail-vein at 74 h after injury at a concentration of 2 million cells per kilogram of body weight. There were three groups of …

Illustrated Abstracts Of The 5th Euplan International Conference, Alexandra Yakusheva, Alexandre Slater, Bernard Payrastre, Cédric Garcia, Giorgia D'Italia, Harriet Allan, Judith M. E. M. Cosemans, Matthew Harper, Meinrad Gawaz, Paul Armstrong, Sara Troitiño, Silvia Maria Grazia Trivigno, Ulhas P. Naik, Yotis A. Senis

Cardeza Foundation for Hematologic Research

These illustrated capsules have been prepared by some speakers of State-of-the-Art talks and of original investigations, presented at the 5^th European Platelet Network (EUPLAN) International Conference, which was held at the Università degli Studi di Milano (Italy) on September 28-30, 2022. The programme featured various state-of-the-art lectures and a selection of oral presentations covering a broad range of topics in platelet and megakaryocyte biology, from basic science to recent advances in clinical studies. As usual, the meeting brought together senior scientists and trainees in an informal atmosphere to discuss platelet science in person.

Species Differences In Platelet Protease-Activated Receptors, Stephanie A Renna, Steven E. Mckenzie, James V. Michael

Cardeza Foundation for Hematologic Research

Protease-activated receptors (PARs) are a class of integral membrane proteins that are cleaved by a variety of proteases, most notably thrombin, to reveal a tethered ligand and promote activation. PARs are critical mediators of platelet function in hemostasis and thrombosis, and therefore are attractive targets for anti-platelet therapies. Animal models studying platelet PAR physiology have relied heavily on genetically modified mouse strains, which have provided ample insight but have some inherent limitations. The current review aims to summarize the notable PAR expression and functional differences between the mouse and human, in addition to highlighting some recently developed tools to further …

Defective Rab31-Mediated Megakaryocytic Early Endosomal Trafficking Of Vwf, Egfr, And M6pr In Runx1 Deficiency, Gauthami Jalagadugula, Guangfen Mao, Lawrence E Goldfinger, Jeremy Wurtzel, Fabiola Del Carpio-Cano, Michele P Lambert, Brian Estevez, Deborah L French, Mortimer Poncz, A Koneti Rao

Cardeza Foundation for Hematologic Research

Transcription factor RUNX1 is a master regulator of hematopoiesis and megakaryopoiesis. RUNX1 haplodeficiency (RHD) is associated with thrombocytopenia and platelet granule deficiencies and dysfunction. Platelet profiling of our study patient with RHD showed decreased expression of RAB31, a small GTPase whose cell biology in megakaryocytes (MKs)/platelets is unknown. Platelet RAB31 messenger RNA was decreased in the index patient and in 2 additional patients with RHD. Promoter-reporter studies using phorbol 12-myristate 13-acetate-treated megakaryocytic human erythroleukemia cells revealed that RUNX1 regulates RAB31 via binding to its promoter. We investigated RUNX1 and RAB31 roles in endosomal dynamics using immunofluorescence staining for markers of …

G Protein-Coupled Receptor Kinase 5 Regulates Thrombin Signaling In Platelets Via Par-1., Kate Downes, Xuefei Zhao, Nicholas S Gleadall, Harriet Mckinney, Carly Kempster, Joana Batista, Patrick L Thomas, Matthew Cooper, James V Michael, Roman Kreuzhuber, Katherine Wedderburn, Kathryn Waller, Bianca Varney, Hippolyte Verdier, Neline Kriek, Sofie E Ashford, Kathleen E Stirrups, Joanne L Dunster, Steven E Mckenzie, Willem H Ouwehand, Jonathan M Gibbins, Jing Yang, William J Astle, Peisong Ma

Cardeza Foundation for Hematologic Research

The interindividual variation in the functional response of platelets to activation by agonists is heritable. Genome-wide association studies (GWASs) of quantitative measures of platelet function have identified fewer than 20 distinctly associated variants, some with unknown mechanisms. Here, we report GWASs of pathway-specific functional responses to agonism by adenosine 5'-diphosphate, a glycoprotein VI-specific collagen mimetic, and thrombin receptor-agonist peptides, each specific to 1 of the G protein-coupled receptors PAR-1 and PAR-4, in subsets of 1562 individuals. We identified an association (P = 2.75 × 10-40) between a common intronic variant, rs10886430, in the G protein-coupled receptor kinase 5 gene (GRK5) …

Predicting Risk Factors For Thromboembolic Complications In Patients With Sickle Cell Anaemia - Lessons Learned For Prophylaxis, Salam Alkindi, Anwaar R Al-Ghadani, Samah R Al-Zeheimi, Said Y Alkindi, Naglaa Fawaz, Samir K. Ballas, Anil V Pathare

Cardeza Foundation for Hematologic Research

Objective: To assess the clinical and laboratory predictors of venous thromboembolism (VTE) in patients with sickle cell anaemia (SCA) and its relationship to morbidity and mortality.

Methods: This retrospective case-control study analysed data from patients with SCA that experienced VTE compared with matched control patients with SCA but no VTE (2:1 ratio).

Results: A total of 102 patients with SCA were enrolled (68 cases with VTE and 34 controls). Amongst the 68 cases (median age, 29.5 years), 26 (38.2%) presented with isolated pulmonary embolism (PE). A higher prevalence of splenectomy (73.5% versus 35.3%) was observed in the cases compared with …

Opioids Are Not A Major Cause Of Death Of Patients With Sickle Cell Disease., Samir K. Ballas

Cardeza Foundation for Hematologic Research

According to the Center of Disease Control and Prevention (CDC) database, the total number of deaths due to opioid overdose from 1999 through 2018 was 840,629. Given the alarming nature of these statistics, patients who requested prescription for opioids became targets of suspicion and possible accusation of maladaptive behavior. Patients with sickle cell disease (SCD) were often not exempt from such accusations and became guilty by association. In order to clarify the effect of opioids on the mortality of patients with SCD, the mortality rates for children and adults with SCD were investigated using the CDC Wide-ranging Online Data for …

Platelets As Drivers Of Ischemia/Reperfusion Injury After Stroke., Noor F Shaik, Raymond F Regan, Ulhas P Naik

Cardeza Foundation for Hematologic Research

Ischemic stroke is a leading cause of morbidity and mortality worldwide and, despite reperfusion either via thrombolysis or thrombectomy, stroke patients often suffer from lifelong disabilities. These persistent neurological deficits may be improved by treating the ischemia/reperfusion (I/R) injury that occurs following ischemic stroke. There are currently no approved therapies to treat I/R injury, and thus it is imperative to find new targets to decrease the burden of ischemic stroke and related diseases. Platelets, cell fragments from megakaryocytes, are primarily known for their role in hemostasis. More recently, investigators have studied the nonhemostatic role of platelets in inflammatory pathologies, such …

Pctp Contributes To Human Platelet Activation By Enhancing Dense Granule Secretion, Shaji Abraham, Lin Ma, Xianguo Kong, Shayan Askari, Leonard Edelstein, Steven Mckenzie

Cardeza Foundation for Hematologic Research

PCTP (phosphatidylcholine transfer protein) was discovered recently to regulate aggregation of human platelets stimulated with PAR4 activating peptide (PAR4AP). However, the role of PCTP following thrombin stimulation, the mechanisms by which PCTP contributes to platelet activation, and the role of PCTP with other receptors remained unknown. As mouse platelets do not express PCTP, we treated human platelets with various agonists in the presence of the specific PCTP inhibitor A1. We observed that PCTP inhibition significantly reduced dense granule secretion in response to thrombin, PAR1AP, PAR4AP, convulxin (GPVI agonist) and FcγRIIA crosslinking. In contrast, among these agonists, PCTP inhibition reduced aggregation …

Determinants Of The Outcome Of The Transition Of Children With Sickle Cell Disease To Adult Programs., Samir K. Ballas, Gaye Riddick-Burden, Elisabeth Congdon-Martin

Cardeza Foundation for Hematologic Research

Transition of adolescents with sickle cell disease to adult programs is associated with increased morbidity and mortality. The reasons for this poor outcome are not well known. This report describes the various factors that affect the outcome of the transition process. These include four inter-personal factors: country of residence, region within the country of residence, the health care system and intra-personal factors. Each factor is described in some detail. Understanding these factors and the establishment of guidelines or recommendations could improve the outcome of this critical transition in the life of patients with sickle cell disease.

Voxelotor Modulates The Analgesic Effect Of Certain Opioids., Samir K. Ballas

Cardeza Foundation for Hematologic Research

No abstract provided.

Opioids And Sickle Cell Disease: From Opium To The Opioid Epidemic., Samir K. Ballas

Cardeza Foundation for Hematologic Research

Sickle cell disease (SCD) is an inherited disorder of hemoglobin structure. The clinical effects of the sickle gene are pleiotropic in nature causing multiple phenotypic expressions associated with the various complications of the disease. The hallmark of the disease is pain that could be acute, chronic, nociceptive, or neuropathic that could occur singly or in various combinations. The acute vaso-occlusive painful crisis (VOC) is the most common cause of admissions to the Emergency Department and/or the hospital. Although progress has been made in understanding the pathophysiology of SCD as well as in developing preventive and curative therapies, effective pain management …

Case Series And Review Of Hematological And Non-Hematological Malignancies In Aging Patients With Sickle Cell Disease In The Hydroxyurea Era., Sanaa Rizk, David J. Axelrod, Rasaq Olaosebikan, Samir K. Ballas

Cardeza Foundation for Hematologic Research

Survival of adult patients with sickle cell disease has increased progressively since the 1970s. Aging patients with sickle cell disease are at risk of developing comorbidities that are not due to sickle cell disease itself, including malignancies. Many studies tried to assess the incidence of malignancy in patients with sickle cell disease. However, no studies have been done to evaluate cancer incidences in aging sickle cell patients, especially in the hydroxyurea (HU) era. In this review, we assessed the prevalence of malignancies in aging patients with sickle cell disease at our institution with or without HU therapy. Retrospective analysis of …

How I Treat Acute And Persistent Sickle Cell Pain., Samir K. Ballas

Cardeza Foundation for Hematologic Research

Sickle pain is the hallmark of sickle cell disease (SCD). It could be acute, persistent/relapsing, chronic, or neuropathic. Although there is a general consensus that pain is a major manifestation of SCD, there is a controversy as to the types of pain and their interrelationship between acute, chronic, relapsing, persistent, etc. This report first reviews the general approach to the management of acute vaso-occlusive crisis (VOC) pain, including education, counseling, pharmacotherapy, non-pharmacotherapy, and fluid therapy. This is followed by the presentation of five patients that represent typical issues that are commonly encountered in the management of patients with SCD. These …

The Vaso-Occlusive Pain Crisis In Sickle Cell Disease: Definition, Pathophysiology, And Management., Deepika S. Darbari, Vivien A. Sheehan, Samir K. Ballas

Cardeza Foundation for Hematologic Research

Early diagnosis, treatment, and prevention of a vaso-occlusive crisis (VOC) are critical to the management of patients with sickle cell disease. It is essential to differentiate between VOC-associated pain and chronic pain, hyperalgesia, neuropathy, and neuropathic pain. The pathophysiology of VOCs includes polymerization of abnormal sickle hemoglobin, inflammation, and adhesion. Hydroxyurea, L-glutamine, crizanlizumab, and voxelotor have been approved by the US Food and Drug Administration for reducing the frequency of VOCs; the European Medicines Agency has approved only hydroxyurea. Other novel treatments are in late-stage clinical development in both the United States and the European Union. The development of agents …

Menopause In Brazilian Women With Sickle Cell Anemia With And Without Hydroxyurea Therapy., Ana Mach Queiroz, Clarisse Lopes De Castro Lobo, Samir K. Ballas

Cardeza Foundation for Hematologic Research

Women with sickle cell anemia (SCA) require special attention for myriad obstetric and gynecologic issues associated with this complex hematologic disorder. These affect all aspects of female life from menarche through menopause. Information regarding obstetric and gynecologic complications of sickle cell disease (SCD), with a few exceptions, is based primarily on observational, anecdotal, retrospective, or cohort studies that may not reflect current aspects of obstetric care.¹ Similarly, there are no recent reports about menopause (also known as climacteric) in women with SCA. The fact that life expectancy of women with SCA was determined to be 46–48 years² delayed …

Bayesian Modelling Of High-Throughput Sequencing Assays With Malacoda., Andrew R Ghazi, Xianguo Kong, Ed S Chen, Leonard C Edelstein, Chad A Shaw

Cardeza Foundation for Hematologic Research

NGS studies have uncovered an ever-growing catalog of human variation while leaving an enormous gap between observed variation and experimental characterization of variant function. High-throughput screens powered by NGS have greatly increased the rate of variant functionalization, but the development of comprehensive statistical methods to analyze screen data has lagged. In the massively parallel reporter assay (MPRA), short barcodes are counted by sequencing DNA libraries transfected into cells and the cell's output RNA in order to simultaneously measure the shifts in transcription induced by thousands of genetic variants. These counts present many statistical challenges, including overdispersion, depth dependence, and uncertain …

Transcutaneous Electrical Nerve Stimulation (Tens) For Pain Management In Sickle Cell Disease., Sudipta Pal, Ruchita Dixit, Soe Moe, Myron Anthony Godinho, Adinegara Bl Abas, Samir K. Ballas, Shanker Ram, Uduman Ali M. Yousuf

Cardeza Foundation for Hematologic Research

BACKGROUND: Sickle cell disease (SCD), one of the most common inherited disorders, is associated with vaso-occlusive pain episodes and haemolysis leading to recurrent morbidity, hospital admissions and work or school absenteeism. The crises are conventionally treated with opioids, non-opioids and other adjuvants with the risk of developing complications, addictions and drug-seeking behaviour. Different non-pharmacological treatments, such as transcutaneous electrical nerve stimulation (TENS) have been used for managing pain in other painful conditions. Hence, the efficacy of TENS for managing pain in SCD needs to be reviewed.

OBJECTIVES: To assess the benefits and harms of TENS for managing pain in people …

Review/Overview Of Pain In Sickle Cell Disease., Samir K. Ballas, Deepika S. Darbari

Cardeza Foundation for Hematologic Research

Sickle cell disease (SCD) is a highly complex inherited disorder of hemoglobin structure. Although the molecular lesion is a single-point mutation, the sickle gene is pleiotropic in nature causing multiple phenotypic expressions that constitute the various complications of the disease. Its manifestations could be acute, chronic, nociceptive, neuropathic that could occur singly or in various combinations. Pain continues to be the major factor of SCD phenotypic complications and the most common cause of admissions to the Emergency Department and/or the hospital. Although progress has been made in understanding the pathophysiology of SCD as well as in developing curative therapies such …

Predictors Of Impending Acute Chest Syndrome In Patients With Sickle Cell Anaemia., Salam Alkindi, Ikhlas Al-Busaidi, Bushra Al-Salami, Samir Raniga, Anil Pathare, Samir K. Ballas

Cardeza Foundation for Hematologic Research

Acute chest syndrome (ACS) is a major complication of sickle cell anaemia (SCA) and a leading cause for hospital admissions and death. We aimed to study the spectrum of clinical and laboratory features of ACS and to assess the predisposing factors and predictors of severity. A retrospective case-control cohort was studied by retrieving patient information from electronic medical records after ethical approval. One hundred adolescents and adults with SCA and hospital admissions for ACS were identified through the discharge summaries, along with 20 additional patients presenting with VOC, but without ACS (controls). Among the patients with ACS, fever (>38.5 …

Grk6 Regulates The Hemostatic Response To Injury Through Its Rate-Limiting Effects On Gpcr Signaling In Platelets., Xi Chen, Shuchi Gupta, Matthew Cooper, Daniel Dehelian, Xuefei Zhao, Meghna U. Naik, Jeremy G.T. Wurtzel, Timothy J. Stalker, Lawrence E. Goldfinger, Jeffrey Benovic, Lawrence F. Brass, Steven E. Mckenzie, Ulhas P. Naik, Peisong Ma

Cardeza Foundation for Hematologic Research

G protein-coupled receptors (GPCRs) mediate the majority of platelet activation in response to agonists. However, questions remain regarding the mechanisms that provide negative feedback toward activated GPCRs to limit platelet activation and thrombus formation. Here we provide the first evidence that GPCR kinase 6 (GRK6) serves this role in platelets, using GRK6-/- mice generated by CRISPR-Cas9 genome editing to examine the consequences of GRK6 knockout on GPCR-dependent signaling. Hemostatic thrombi formed in GRK6-/- mice are larger than in wild-type (WT) controls during the early stages of thrombus formation, with a rapid increase in platelet accumulation at the site of injury. …

The Evolving Pharmacotherapeutic Landscape For The Treatment Of Sickle Cell Disease., Samir K Ballas

Cardeza Foundation for Hematologic Research

Sickle cell disease (SCD) is an extremely heterogeneous disease that has been associated with global morbidity and early mortality. More effective and inexpensive therapies are needed. During the last five years, the landscape of the pharmacotherapy of SCD has changed dramatically. Currently, 54 drugs have been used or under consideration to use for the treatment of SCD. These fall into 3 categories: the first category includes the four drugs (Hydroxyurea, L-Glutamine, Crizanlizumab tmca and Voxelotor) that have been approved by the United States Food and Drug Administration (FDA) based on successful clinical trials. The second category includes 22 drugs that …

Treatment Of Dental Complications In Sickle Cell Disease., Priti Mulimani, Samir K. Ballas, Adinegara Bl Abas, Laxminarayan Karanth

Cardeza Foundation for Hematologic Research

BACKGROUND: Sickle cell disease is the most common single gene disorder and the commonest haemoglobinopathy found with high prevalence in many populations across the world. Management of dental complications in people with sickle cell disease requires special consideration for three main reasons. Firstly, dental and oral tissues are affected by the blood disorder resulting in several oro-facial abnormalities. Secondly, living with a haemoglobinopathy and coping with its associated serious consequences may result in individuals neglecting their oral health care. Finally, the treatment of these oral complications must be adapted to the systemic condition and special needs of these individuals, in …

Pharmacological Interventions For Painful Sickle Cell Vaso-Occlusive Crises In Adults., Tess E. Cooper, Ian R. Hambleton, Samir K. Ballas, Brydee A. Johnston, Philip J. Wiffen

Cardeza Foundation for Hematologic Research

BACKGROUND: Sickle cell disease (SCD) is a group of inherited disorders of haemoglobin (Hb) structure in a person who has inherited two mutant globin genes (one from each parent), at least one of which is always the sickle mutation. It is estimated that between 5% and 7% of the world's population are carriers of the mutant Hb gene, and SCD is the most commonly inherited blood disorder. SCD is characterized by distorted sickle-shaped red blood cells. Manifestations of the disease are attributed to either haemolysis (premature red cell destruction) or vaso-occlusion (obstruction of blood flow, the most common manifestation). Shortened …

Validation Of A Miniaturized Permeability Assay Compatible With Crispr-Mediated Genome-Wide Screen., Claire Simonneau, Junning Yang, Xianguo Kong, Robert Kilker, Leonard Edelstein, Paolo Fortina, Eric R. Londin, Arie Horowitz

Cardeza Foundation for Hematologic Research

The impermeability of the luminal endothelial cell monolayer is crucial for the normal performance of the vascular and lymphatic systems. A key to this function is the integrity of the monolayer's intercellular junctions. The known repertoire of junction-regulating genes is incomplete. Current permeability assays are incompatible with high-throughput genome-wide screens that could identify these genes. To overcome these limitations, we designed a new permeability assay that consists of cell monolayers grown on ~150 μm microcarriers (MCs). Each MC functions as a miniature individual assay of permeability (MAP). We demonstrate that false-positive results can be minimized, and that MAP sensitivity to …