BackgroundRecently, the safety of repeated and lengthy anesthesia administration has been called into question, a subset of these animal studies demonstrated that anesthetics induced blood-brain barrier (BBB) dysfunction. The BBB is critical in protecting the brain parenchyma from the surrounding micro-vasculature. BBB breakdown and dysfunction has been observed in several neurodegenerative diseases and may contribute to both the initiation and the progression of the disease. In this study we utilize a human induced pluripotent stem cell (iPSC) derived-BBB model, exhibiting near in vivo properties, to evaluate the effects of anesthetics on critical barrier properties.MethodsiPSC-derived brain microvascular endothelial cells (BMECs) expressed near in vivo barrier tightness assessed by trans-endothelial electrical resistance and para-cellular permeability. Efflux transporter activity was determined by substrate transport in the presence of specific inhibitors. Trans-cellular transport was measured utilizing large fluorescently tagged dextran. Tight junction localization in BMECs was evaluated with fluorescent microscopy. The anesthetic, propofol was exposed to BMECs at varying durations and concentrations and BBB properties were monitored post-exposure.ResultsFollowing propofol exposure, BMECs displayed reduced resistance and increased permeability indicative of a leaky barrier. Reduced barrier tightness and the dysregulation of occludin, a tight junction protein, were partly the result of an elevation in matrix metalloproteinase (MMP) levels. Efflux transporter activity and trans-cellular transport were unaffected by propofol exposure. Propofol induced barrier dysfunction was partially restored following matrix metalloproteinase inhibition.ConclusionFor the first time, we have demonstrated that propofol alters BBB integrity utilizing a human in vitro BBB model that displays key in vivo characteristics. A leaky BBB enables otherwise impermeable molecules such as pathogens and toxins the ability to reach vulnerable cell types of the brain parenchyma. A robust human in vitro BBB model will allow for the evaluation of several anesthetics at fluctuating clinical scenarios and to elucidate mechanisms with the goal of ultimately improving anesthesia safety.

Coronavirus disease 2019 (COVID-19) has presented a unique challenge to student-run free clinics (SRFCs), with many closing for several months and all needing to find ways to adapt to the new “normal” of the pandemic. While the prospect of new variants and higher surges continues to threaten our ability to keep SRFC doors open to serve the neediest patients among our community, we present here arguments from need, practicality, safety, and ethics that COVID-19 is the ideal time to maintain—and, even expand—the services SRFCs provide. With so many patients relying on SRFCs for their primary care and with the ability to use precautionary measures to safely see and treat patients, SRFCs should play a vital role in helping the overburdened healthcare system continue to function and provide needed care, despite the devastating impacts of COVID-19.

Background: In 2016, the FDA released a report concerning the use of anesthetics in young children and pregnant women. This report states that prolonged or repeat exposure to anesthetic may lead to neurodevelopmental delay. Previously, Canfield et al., had determined a method for developing a human blood brain barrier model from induced pluripotent stem cells (iPSC). Preliminary data has shown that exposing this model to propofol at relevant concentrations significantly reduces barrier strength and may promote leakiness of the blood brain barrier.  Design/Methods: Our efforts during these ten weeks focused on the effects of propofol on transcellular mechanisms in iPSC-derived brain microvasculature endothelial cells (BMEC). After exposing to propofol, fluorescently labeled dextran transcytosis and accumulation was analyzed on a fluorescent plate reader. Specifically, we monitored the transcellular movement of different molecular weighted dextrans.  Results: Treatment of BMECs with 50uM propofol increased transcytosis and accumulation of 10kDa dextran as compared to control. Increased transcytosis in the absence of increased accumulation of 3kDa dextran may provide evidence of paracellular transport. Transcytosis and accumulation of 40kDa dextran were unchanged between treatment and control groups. These data may provide evidence that propofol affects transcytosis mechanisms differently.  Potential Impact: We hope to more fully understand the mechanism by which anesthetics such as propofol effect the blood brain barrier. Due to the presence of tight junction proteins, transcytosis is an important mechanism for moving materials into the brain parenchyma. Further research will need to be done to determine the mechanism by which propofol affects BMEC transcytosis.