James L. Kingsley

Bio: James L. Kingsley is an academic researcher from Worcester Polytechnic Institute. The author has contributed to research in topics: Fluorescence recovery after photobleaching & Sperm. The author has an hindex of 6, co-authored 17 publications receiving 261 citations.

Exhaustion of Racing Sperm in Nature-Mimicking Microfluidic Channels During Sorting

Abstract: Fertilization is central to the survival and propagation of a species, however, the precise mechanisms that regulate the sperm's journey to the egg are not well understood. In nature, the sperm has to swim through the cervical mucus, akin to a microfluidic channel. Inspired by this, a simple, cost-effective microfluidic channel is designed on the same scale. The experimental results are supported by a computational model incorporating the exhaustion time of sperm.

Selection of functional human sperm with higher DNA integrity and fewer reactive oxygen species.

Abstract: Fertilization and reproduction are central to the survival and propagation of a species. Couples who cannot reproduce naturally have to undergo in vitro clinical procedures. An integral part of these clinical procedures includes isolation of healthy sperm from raw semen. Existing sperm sorting methods are not efficient and isolate sperm having high DNA fragmentation and reactive oxygen species (ROS), and suffer from multiple manual steps and variations between operators. Inspired by in vivo natural sperm sorting mechanisms where vaginal mucus becomes less viscous to form microchannels to guide sperm towards egg, a chip is presented that efficiently sorts healthy, motile and morphologically normal sperm without centrifugation. Higher percentage of sorted sperm show significantly lesser ROS and DNA fragmentation than the conventional swim-up method. The presented chip is an easy-to-use high-throughput sperm sorter that provides standardized sperm sorting assay with less reliance on operators's skills, facilitating reliable operational steps.

Guidance and Self-Sorting of Active Swimmers: 3D Periodic Arrays Increase Persistence Length of Human Sperm Selecting for the Fittest.

Abstract: Male infertility is a reproductive disease, and existing clinical solutions for this condition often involve long and cumbersome sperm sorting methods, including preprocessing and centrifugation-based steps. These methods also fall short when sorting for sperm free of reactive oxygen species, DNA damage, and epigenetic aberrations. Although several microfluidic platforms exist, they suffer from structural complexities, i.e., pumps or chemoattractants, setting insurmountable barriers to clinical adoption. Inspired by the natural filter-like capabilities of the female reproductive tract for sperm selection, a model-driven design, featuring pillar arrays that efficiently and noninvasively isolate highly motile and morphologically normal sperm, with lower epigenetic global methylation, from raw semen, is presented. The Simple Periodic ARray for Trapping And isolatioN (SPARTAN) created here modulates the directional persistence of sperm, increasing the spatial separation between progressive and nonprogressive motile sperm populations within an unprecedentedly short 10 min assay time. With over 99% motility of sorted sperm, a 5-fold improvement in morphology, 3-fold increase in nuclear maturity, and 2-4-fold enhancement in DNA integrity, SPARTAN offers to standardize sperm selection while eliminating operator-to-operator variations, centrifugation, and flow. SPARTAN can also be applied in other areas, including conservation ecology, breeding of farm animals, and design of flagellar microrobots for diagnostics.

F-Actin Mediated Focusing of Vesicles at the Cell Tip Is Essential for Polarized Growth.

Abstract: F-actin has been shown to be essential for tip growth in an array of plant models, including Physcomitrella patens One hypothesis is that diffusion can transport secretory vesicles, while actin plays a regulatory role during secretion. Alternatively, it is possible that actin-based transport is necessary to overcome vesicle transport limitations to sustain secretion. Therefore, a quantitative analysis of diffusion, secretion kinetics, and cell geometry is necessary to clarify the role of actin in polarized growth. Using fluorescence recovery after photobleaching analysis, we first show that secretory vesicles move toward and accumulate at the tip in an actin-dependent manner. We then depolymerized F-actin to decouple vesicle diffusion from actin-mediated transport and measured the diffusion coefficient and concentration of vesicles. Using these values, we constructed a theoretical diffusion-based model for growth, demonstrating that with fast-enough vesicle fusion kinetics, diffusion could support normal cell growth rates. We further refined our model to explore how experimentally extrapolated vesicle fusion kinetics and the size of the secretion zone limit diffusion-based growth. This model predicts that diffusion-mediated growth is dependent on the size of the region of exocytosis at the tip and that diffusion-based growth would be significantly slower than normal cell growth. To further explore the size of the secretion zone, we used a cell wall degradation enzyme cocktail and determined that the secretion zone is smaller than 6 μm in diameter at the tip. Taken together, our results highlight the requirement for active transport in polarized growth and provide important insight into vesicle secretion during tip growth.

Physical Biology of the Cell

Abstract: Physical Biology of the Cell, 2nd Edition, is a textbook that focuses on the application of physical principles to understanding biological systems. The subject matter of the text is organized according to common physical principles that govern biological processes rather than in relation to the biological processes themselves, as is common for most biology and cell biology textbooks. Topics covered in the book span a broad range of interests, including electrostatics, molecular interactions, molecular motors and the cytoskeleton, and membranes. Each chapter features color figures, derived equations with relevant examples, and problem sets at the chapter’s conclusion. The problem sets at the end of the chapters are expanded from the first edition. Further, the second edition includes two new chapters, one on light and pattern formation, and another on the use of computation in exploring biological problems. Additional student and instructor resources are also available online. The primary audience for the textbook could include advanced undergraduate students or first-year graduate students. While the textbook may be best suited for a biophysics course, it could also be used as a primary or supplementary text for teaching cellular and molecular biology. As a teaching tool for cellular and molecular biology, the many examples featured throughout the text could easily be employed to assist students in learning the principles of how a cellular or molecular system functions. A basic level of mathematical proficiency would be required of the student. While this textbook could be an excellent resource for many courses, there are several topics commonly covered in biochemistry classes, such the glycolytic pathway, that are featured in the book but in different contexts than many widely used biochemistry texts. For a biophysics course that is heavily focused on techniques, individual references that discuss the specific techniques in detail would be more suitable than this book. Of course, any instructor seeking to use this textbook should be aware of its content before making a selection. This textbook is an excellent resource, both for a research scientist and for a teacher. The authors do a superb job of selecting the material for each chapter and explaining the material with equations and narrative in an easily digestible manner. Readers who enjoy this book may also enjoy Molecular Driving Forces by Dill and Bromberg, which gives excellent treatment of similar concepts.

Engineering cancer microenvironments for in vitro 3-D tumor models

Abstract: The natural microenvironment of tumors is composed of extracellular matrix (ECM), blood vasculature, and supporting stromal cells. The physical characteristics of ECM as well as the cellular components play a vital role in controlling cancer cell proliferation, apoptosis, metabolism, and differentiation. To mimic the tumor microenvironment outside the human body for drug testing, two-dimensional (2-D) and murine tumor models are routinely used. Although these conventional approaches are employed in preclinical studies, they still present challenges. For example, murine tumor models are expensive and difficult to adopt for routine drug screening. On the other hand, 2-D in vitro models are simple to perform, but they do not recapitulate natural tumor microenvironment, because they do not capture important three-dimensional (3-D) cell–cell, cell–matrix signaling pathways, and multi-cellular heterogeneous components of the tumor microenvironment such as stromal and immune cells. The three-dimensional (3-D) in vitro tumor models aim to closely mimic cancer microenvironments and have emerged as an alternative to routinely used methods for drug screening. Herein, we review recent advances in 3-D tumor model generation and highlight directions for future applications in drug testing.

Paper-based analytical devices for clinical diagnosis: recent advances in the fabrication techniques and sensing mechanisms.

Abstract: Introduction: There is a significant interest in developing inexpensive portable biosensing platforms for various applications including disease diagnostics, environmental monitoring, food safety, and water testing at the point-of-care (POC) settings. Current diagnostic assays available in the developed world require sophisticated laboratory infrastructure and expensive reagents. Hence, they are not suitable for resource-constrained settings with limited financial resources, basic health infrastructure, and few trained technicians. Cellulose and flexible transparency paper-based analytical devices have demonstrated enormous potential for developing robust, inexpensive and portable devices for disease diagnostics. These devices offer promising solutions to disease management in resource-constrained settings where the vast majority of the population cannot afford expensive and highly sophisticated treatment options.Areas covered: In this review, the authors describe currently developed cellulose and...

Medical Micro/Nanorobots in Precision Medicine.

Abstract: Advances in medical robots promise to improve modern medicine and the quality of life. Miniaturization of these robotic platforms has led to numerous applications that leverages precision medicine. In this review, the current trends of medical micro and nanorobotics for therapy, surgery, diagnosis, and medical imaging are discussed. The use of micro and nanorobots in precision medicine still faces technical, regulatory, and market challenges for their widespread use in clinical settings. Nevertheless, recent translations from proof of concept to in vivo studies demonstrate their potential toward precision medicine.