Annual Review of Biomedical Engineering最新文献

As health care systems worldwide seek to decentralize diagnostics and expand precision medicine, silicon photonic biosensors have become a compelling solution. Their development over the past decade, especially in the last 5 years, marks a significant convergence of photonics, nanotechnology, and biomedical engineering that aims to reshape the diagnostic landscape. This review presents a comprehensive analysis of advances in silicon photonic biosensors, focusing on key configurations including microring resonators, photonic crystals, interferometers, and other emerging transduction mechanisms. We discuss the integration of advanced surface functionalization strategies for efficient and robust bioreceptor immobilization, which is critical for reliable biomedical applications. We emphasize the translation of these devices into clinical settings, primarily in infectious diseases and cancer diagnostics. Finally, we address current limitations, such as fabrication complexity, microfluidic integration, and data interpretation, and outline future directions to enhance scalability and clinical adoption in personalized medicine and decentralized health care.

The autonomic nervous system (ANS) plays a vital role in health care for both acute care and chronic diseases. The traditional view of the ANS is to divide it into individual organ systems and study the separate components with a reductionist approach, which has been proven insufficient. Here, we argue that a holistic network-level view of the ANS is critical for generating new insights and deepening our understanding of its complex and dynamic functions. In this review, we treat the ANS as such a coordinated and dynamic network. We advocate for studying its interactions with major organ systems and the central nervous system using continuous and longitudinal monitoring in ambulatory and at-home settings rather than clinic-based snapshots. We first briefly review ANS physiology, then outline our network perspective, and finally highlight cutting-edge research directions and emerging engineering innovations in ANS monitoring, modeling, and modulation that benefit from this network-level view.

Electrical stimulation of the brain is being developed as a treatment for an increasing number of neurological disorders. Technologies for delivering electrical stimulation are advancing rapidly and vary in specificity, coverage, and invasiveness. Supracortical microstimulation (SCMS), characterized by microelectrode contacts placed on the epidural or subdural cortical surface, achieves a balance between the advantages and limitations of other electrical stimulation technologies by delivering spatially precise activation without disrupting the integrity of the cortex. However, in vivo experiments involving SCMS have not been comprehensively summarized. Here, we review the field of SCMS, focusing on recent advances, to guide the development of clinically translatable supracortical microelectrodes. We also highlight the gaps in our understanding of the biophysical effects of this technology. Future work investigating the unique electrochemical properties of supracortical microelectrodes and validating SCMS in nonhuman primate preclinical studies can enable rapid clinical translation of innovative treatments for humans with neurological disorders.

Over the last decade, a plethora of organoid models have been generated to recapitulate aspects of human development, disease, tissue homeostasis, and repair. Organoids representing multiple tissues have emerged and are typically categorized based on their origin. Tissue-derived organoids are established directly from tissue-resident stem/progenitor cells of either adult or fetal origin. Starting from pluripotent stem cells (PSCs), PSC-derived organoids instead recapitulate the developmental trajectory of a given organ. Gene editing technologies, particularly the CRISPR-Cas toolbox, have greatly facilitated gene manipulation experiments with considerable ease and scalability, revolutionizing organoid-based human biology research. Here, we review the recent adaptation of CRISPR-based screenings in organoids. We examine the strategies adopted to perform CRISPR screenings in organoids, discuss different screening scopes and readouts, and highlight organoid-specific challenges. We then discuss individual organoid-based genome screening studies that have uncovered novel genes involved in a variety of biological processes. We close by providing an outlook on how widespread adaptation of CRISPR screenings across the organoid field may be achieved, to ultimately leverage our understanding of human biology.

Medical ultrasound is a diagnostic imaging modality used for visualizing internal organs; the frequencies typically used are 2-10 MHz. Scanning acoustic microscopy (SAM) is a form of ultrasound where frequencies typically exceed 50 MHz. Increasing the acoustic frequency increases the specimen's spatial resolution but reduces the imaging depth. The advantages of using SAM over conventional light and electron microscopy include the ability to image cells and tissues without any preparation that could kill or alter them, providing a more accurate representation of the specimen. After scanning the specimen, acoustic signals are merged into an image on the basis of changes in the impedance mismatch between the immersion fluid and the specimens. The acoustic parameters determining the image quality are absorption and scattering. Surface scans can assess surface characteristics of the specimen. SAM is also capable of elastography, that is, studying elastic properties to discern differences between healthy and affected tissues. SAM has significant potential for detection/analysis in research and clinical studies.

Regulation of the brain's neuroimmune system is central to development, normal function, and disease. Neuronal communication to microglia, the primary immune cells of the brain, is well known to involve purinergic signaling mediated via ATP secretion and the cytokine fractalkine. Recent evidence shows that neurons release multiple cytokines beyond fractalkine, yet these are less studied and poorly understood. In contrast to ATP, cytokines are a class of signaling molecule that are much larger, with longer signaling and farther diffusion. We posit that neuron-expressed cytokines are an essential mechanism of neuron-microglia communication that arises as part of both normal learning and memory and in response to tissue pathology. Thus, neurons are underappreciated immunomodulatory cells that express diverse immunomodulatory signals. While neuronally sourced cytokines have been understudied, new technical advances make this a timely topic. The goal of this review is to define what is known about the cytokines expressed from neurons, how they are regulated, and the effects of these cytokines on microglia. We delineate key knowledge gaps and needs for new tools to define and analyze neuronal roles in immunomodulation. Given that cytokines are central regulators of microglial function, a broad new body of work is required to illuminate functional links between these neuronally expressed cytokines and sustained and transient microglial function.

Cochlear implants are the most successful neural prostheses used to restore hearing in severe-to-profound hearing-impaired individuals. The field of cochlear implant coding investigates interdisciplinary approaches to translate acoustic signals into electrical pulses transmitted at the electrode-neuron interface, ranging from signal preprocessing algorithms, enhancement, and feature extraction methodologies to electric signal generation. In the last five decades, numerous coding strategies have been proposed clinically and experimentally. Initially developed to restore speech perception, increasing computational possibilities now allow coding of more complex signals, and new techniques to optimize the transmission of electrical signals are constantly gaining attention. This review provides insights into the history of multichannel coding and presents an extensive list of implemented strategies. The article briefly addresses each method and considers promising future directions of neural prostheses and possible signal processing, with the ultimate goal of providing a current big picture of the large field of cochlear implant coding.

The microvasculature, a complex network of small blood vessels, connects systemic circulation with local tissues, facilitating the nutrient and oxygen exchange that is critical for homeostasis and organ function. Engineering these structures is paramount for advancing tissue regeneration, disease modeling, and drug testing. However, replicating the intricate architecture of native vascular systems-characterized by diverse vessel diameters, cellular constituents, and dynamic perfusion capabilities-presents significant challenges. This complexity is compounded by the need to precisely integrate biomechanical, biochemical, and cellular cues. Recent breakthroughs in microfabrication, organoids, bioprinting, organ-on-a-chip platforms, and in vivo vascularization techniques have propelled the field toward faithfully replicating vascular complexity. These innovations not only enhance our understanding of vascular biology but also enable the generation of functional, perfusable tissue constructs. Here, we explore state-of-the-art technologies and strategies in microvascular engineering, emphasizing key advancements and addressing the remaining challenges to developing fully functional vascularized tissues.

People who have lost the ability to speak due to neurological injuries would greatly benefit from assistive technology that provides a fast, intuitive, and naturalistic means of communication. This need can be met with brain-computer interfaces (BCIs): medical devices that bypass injured parts of the nervous system and directly transform neural activity into outputs such as text or sound. BCIs for restoring movement and typing have progressed rapidly in recent clinical trials; speech BCIs are the next frontier. This review covers the clinical need for speech BCIs, surveys foundational studies that point to where and how speech can be decoded in the brain, describes recent progress in both discrete and continuous speech decoding and closed-loop speech BCIs, provides metrics for assessing these systems' performance, and highlights key remaining challenges on the road toward clinically useful speech neuroprostheses.

With increasing demands for continuous health monitoring remotely, wearable and implantable devices have attracted considerable interest. To fulfill such demands, novel materials and device structures have been investigated, since commercial biomedical devices are not compatible with flexible and conformable form factors needed for soft tissue monitoring and intervention. Among various materials, piezoelectric materials have been widely adopted for multiple applications including sensing, energy harvesting, neurostimulation, drug delivery, and ultrasound imaging owing to their unique electromechanical conversion properties. In this review, we provide a comprehensive overview of piezoelectric-based wearable and implantable biomedical devices. We first provide the basic principles of piezoelectric devices and device design strategies for wearable and implantable form factors. Then, we discuss various state-of-the-art applications of wearable and implantable piezoelectric devices and their design strategies. Finally, we demonstrate several challenges and outlooks for designing piezoelectric-based conformable biomedical devices.