The Annals of Biomedical Engineering (ABME) depends on the voluntary service of reviewers to select and refine submissions to be published in the journal. ABME was especially reliant on reviewers in 2020 with a record number of papers submitted, including 460 that went out for review. We would like to thank all of our reviewers for their commitment and service to ABME. A total of 808 individuals from academia and industry from 55 countries reviewed ABME papers last year. We have highlighted reviewers that completed 4 or more reviews for their exemplary service in Table 1. The remainder of this article will summarize some of the top papers published in 2020 that our reviewers helped to refine. These papers represent growing areas of biomedical engineering, including regenerative medicine, drug delivery, concussion biomechanics, medical robotics, modeling, and gender diversity within the field.

Table 1 ABME reviewers that completed the most reviews during 2020
Full size table

Regenerative Medicine

Regenerative medicine is a rapidly growing field within biomedical engineering that includes stem cell therapies, tissue engineering, and growth of artificial organs. The most viewed and cited regenerative medicine papers in ABME last year covered a variety of topics including extracellular matrix materials, new biomaterials for vascular repair, and novel tissue engineering approaches to cartilage repair. Cramer and Badylak reviewed different biologic scaffold preparation methods from allogeneic or xenogeneic extracellular matrix.3 They found that clinical outcome of tissue repairs using biologic scaffolds varied widely depending on the methods used. Ding et al. developed a new injectable hydrogel to promote formation of blood vessels and repair of damaged tissue.9 The hydrogel was loaded with growth factor nanoparticles and showed improved vascularization and tissue repair in both in vitro and animal models. McKittrick et al. developed a novel coronary stent coating that rapidly releases an antiproliferative agent.15 The coating is composed of a bioactive polymer that promotes re-endothelialisation, which has been a challenge for other stents that release antiproliferative drugs to prevent artery wall thickening. The combination of antiproliferative drug release while still supporting endothelial cell growth is promising for patient outcome. De Moor et al. generated cartilage spheroid microtissues to be injected in joint lesions and aid in regeneration.6 Other regenerative cell therapies for cartilage tend to form fibrous tissue instead of cartilage, so these microtissues offer a promising alternative for a tissue type with limited self-healing ability.

Drug Delivery

Drug delivery systems have become increasingly complex in recent years, combining engineering strategies with advances in biomaterials and nanomedicine. These new technologies have improved targeted drug delivery and bioavailability to affected tissues while limiting side effects. Targets of new drug delivery systems highlighted in 2020 issues of ABME included skin, coronary arteries, and brain. Cu et al. compared drug diffusion for topical application, solid needle injection, and needle-free micro-jet injection.4 Needle-free injection has the fastest diffusion rates and causes less tissue damage than a solid needle, while topical application is the slowest delivery method but does not cause tissue damage. The McKittrick et al. study described above under regenerative medicine used a new biomaterial coating for coronary stents that was loaded with an antiproliferative agent.15 The stent coating promotes endothelial cell growth while controlled release of the antiproliferative drug prevents restenosis of the artery. Moya et al. developed a platform for customizing an in vitro blood-brain barrier model.17 The model can be 2D or 3D, contain a single cell type or co-culture, and can be used with static or continuous flow conditions. This model can be used for studying blood-brain barrier function, or developing new therapeutics.

Concussion Biomechanics

Concussion has gained growing media attention and public awareness as evidence for long-term deficits from repeated concussions has surfaced. A number of papers on concussion biomechanics were published in ABME in 2020, including a special issue devoted to the topic. Campolettano et al. modeled risk of concussion for youth football players as a function of linear and rotational head acceleration.2 On-field head impact kinematics from youth football players were used to develop the risk function, which showed age-related differences in concussion tolerance compared to adult athletes. Bland et al. developed an evaluation system for determining relative bicycle helmet protective performance.1 The metric used to summarize helmet performance in laboratory tests identified differences in protection between helmet models. Decker et al. developed and validated a football helmet finite element model.7 Similar models could be used to evaluate the effects of helmet design modifications on protective capability. These tools could be used by manufacturers to improve helmet designs.

Medical Robotics

Medical robotics is a relatively new field within biomedical engineering, with the first documented clinical case of a surgical robot used for a brain biopsy in 1985.5,11 With advances in technology, robotics have been applied to a broad spectrum of medical procedures. Lv et al. developed a novel palpation force sensor for use during minimally invasive surgery.14 The fiber Bragg grating-based sensor overcomes limitations of previously proposed sensor designs with its miniature size and biocompatibility. This novel technology could allow surgeons to perform more complex and delicate minimally invasive procedures, and to identify abnormal tissues during procedures. Lai et al. proposed a combined sensor-model approach to provide haptic feedback for surgeons using flexible endoscopic surgical robots.12 Force is measured directly with a fiber Bragg grating-based force sensor on one of the tendon-sheath mechanisms in the robot, while modeling is used to estimate forces in the other tendon-sheath mechanisms. The use of a single sensor provides a space-saving and robust solution for haptic feedback.

Modeling

Computational modeling has been applied to all areas of biomedical engineering, and has potential to greatly reduce time and resources needed for experimental research. The most prominent modeling papers in ABME in 2020 were in the fields of cardiology, musculoskeletal biomechanics, and concussion biomechanics. Lee et al. developed computational models of bioprosthetic heart valves in an experimental pulse-duplicator platform.13 The models closely matched experimental results, and could be used to expedite design and regulation of new bioprosthetic heart valves. Modenese and Kohout proposed a novel technique for automatically generating subject-specific complex muscle geometries for musculoskeletal models.16 Muscle surface geometries from medical images are used to generate a user-defined number of muscle fibers in the model. This technique can be used to improve personalized musculoskeletal and finite element models. Hosseini Nasab et al. quantified collateral ligament elongation patterns for normal functional activities in patients that underwent total knee arthroplasty.10 Consistent patterns were found in different activities, and were sensitive to femoral attachment points, indicating the importance of the femoral component of the implant in determining post-operative function. As described above under concussion biomechanics, Decker et al. developed a finite element model of a football helmet.7 The model, when used with a test dummy head model, can be subjected to simulated laboratory head impacts to evaluate helmet performance and determine the effects of design modifications.

Diversity

Diversity has become an increasingly important topic in all professions. It is important to consider not only bias in a workforce, but also any perceived bias that may inhibit performance and growth of employees. Denend et al. evaluated gender representation in senior leadership and perceptions of the workplace in health technology professionals.8 They found that women are underrepresented and perceive gender bias as a barrier to leadership roles more than men do.

The success of ABME in the last year would not have been possible without the dedication of our reviewers. The exemplary papers above show the breadth of knowledge and expertise they provide, and we would again like to thank them for their service. We look forward to another year of publishing impactful research in the field of biomedical engineering.