Developing Regenerative Treatments for Developmental Defects, Injuries, and Diseases Using Extracellular Matrix Collagen-Targeting Peptides.

Collagen is the most widespread extracellular matrix (ECM) protein in the body and is important in maintaining the functionality of organs and tissues. Studies have explored interventions using collagen-targeting tissue engineered techniques, using collagen hybridizing or collagen binding peptides, to target or treat dysregulated or injured collagen in developmental defects, injuries, and diseases. Researchers have used collagen-targeting peptides to deliver growth factors, drugs, and genetic materials, to develop bioactive surfaces, and to detect the distribution and status of collagen. All of these approaches have been used for various regenerative medicine applications, including neovascularization, wound healing, and tissue regeneration. In this review, we describe in depth the collagen-targeting approaches for regenerative therapeutics and compare the benefits of using the different molecules for various present and future applications.

Approaches to Characterize and Quantify Extracellular Vesicle Surface Conjugation Efficiency.

Extracellular vesicles (EVs) are cell-secreted nanovesicles that play an important role in long-range cell-cell communication. Although EVs pose a promising alternative to cell-based therapy, targeted in vivo delivery still falls short. Many studies have explored the surface modification of EVs to enhance their targeting capabilities. However, to our knowledge, there are no standardized practices to confirm the successful surface modification of EVs or calculate the degree of conjugation on EV surfaces (conjugation efficiency). These pieces of information are essential in the reproducibility of targeted EV therapeutics and the determination of optimized conjugation conditions for EVs to see significant therapeutic effects in vitro and in vivo. This review will discuss the vast array of techniques adopted, technologies developed, and efficiency definitions made by studies that have calculated EV/nanoparticle surface conjugation efficiency and how differences between studies may contribute to differently reported conjugation efficiencies.

Assessing the conjugation efficiency of surface-modified extracellular vesicles using single nanovesicle analysis technologies.

Extracellular vesicles (EVs) are cell-secreted nanoscale vesicles with important roles in cell-cell communication and drug delivery. Although EVs pose a promising alternative to cell-based therapy, targeted delivery in vivo is lacking. Their surface is often modified to endow them with active targeting molecules to enable specific cell uptake and tailor EV biodistribution. A dominant paradigm has been to evaluate the EV surface functionalization using bulk analysis assays, such as western blotting and bead-based flow cytometry. Yet, the heterogeneity of EVs is now recognized as a major bottleneck for their clinical translation. Here, we engineer the EV surface at the single-vesicle level. We applied orthogonal platforms with single vesicle resolution to determine and optimize the efficiency of conjugating the myelin-targeting aptamer LJM-3064 to single EVs (Apt-EVs). The aptamers were conjugated using either lipid insertion or covalent protein modification, followed by an assessment of single-EV integrity and stability. We observed unique aptamer conjugation to single EVs that depends on EV size. Our study underscores the importance of single vesicle analysis for engineering EVs and provides a novel single-EV-based framework for modifying EV surfaces.

Concept Mapping as a Metacognition Tool in a Problem-Solving-Based BME Course During In-Person and Online Instruction.

Metacognitive skills can have enormous benefits for students within engineering courses. Unfortunately, these metacognitive skills tend to fall outside the content area of most courses, and consequently, they can often be neglected in instruction. In this context, previous research on concept mapping as a teaching strategy points to meaningful learning. The purpose of this innovation paper is to report an application of concept mapping (1) to facilitate metacognition steps in students, and (2) to identify the muddiest points students struggle with, during both in-person and online instruction of a problem-solving-based biomedical engineering course. This innovation article also looks at the usefulness of concept mapping through instructor and student perceptions and students' class performance. The entire concept mapping intervention was conducted during weeks 8-10 of the Spring 2019 in-person quarter and during weeks 3-4 and 8-10 of the Spring 2021 online quarter. The exercise involved concept mapping, explanation and discussion with peers, and answering structured reflection prompts. Each concept map activity was contextualized to the metacognitive knowledge domain of the revised Bloom's taxonomy. The average class performance was compared between students who completed concept mapping vs. those who did not, using a t-test and one-way ANOVA at alpha = 0.05 significance level followed by a Tukey HSD test. Students' concept maps and reported answers were analyzed qualitatively following the concept mapping intervention. During the Spring 2019 in-person quarter, 59.30% of students completed concept mapping with reflection, whereas 47.67% completed it in spring 2021 online instruction. A two-tailed, unpaired t-test indicated that concept mapping did not significantly enhance students' class performance (p > 0.05) within each of the in-person and online instructions. Peers' suggestions to students to improve concept maps revealed themes related to course concepts, prerequisite concepts, and the act of concept mapping itself. Concept mapping was effective in revealing the muddiest points of the course. Concept mapping did not significantly enhance students' class performance either in-person or online instruction (effect sizes were 0.29 for the 2019 in-person quarter and 0.33 for the 2021 online quarter). However, instructors and students' perceptions reflected that concept mapping facilitated metacognition in a problem-solving-based biomedical engineering course both during in-person and online instruction. Most students (78%) were optimistic about the usefulness of concept mapping for this course, and 84% were inclined to apply it for a variety of other courses. Supplementary Information: The online version contains supplementary material available at 10.1007/s43683-022-00066-3.

Development and Characterization of Bioinspired Lipid Raft Nanovesicles for Therapeutic Applications.

Lipid rafts are highly ordered regions of the plasma membrane enriched in signaling proteins and lipids. Their biological potential is realized in exosomes, a subclass of extracellular vesicles (EVs) that originate from the lipid raft domains. Previous studies have shown that EVs derived from human placental mesenchymal stromal cells (PMSCs) possess strong neuroprotective and angiogenic properties. However, clinical translation of EVs is challenged by very low, impure, and heterogeneous yields. Therefore, in this study, lipid rafts are validated as a functional biomaterial that can recapitulate the exosomal membrane and then be synthesized into biomimetic nanovesicles. Lipidomic and proteomic analyses show that lipid raft isolates retain functional lipids and proteins comparable to PMSC-EV membranes. PMSC-derived lipid raft nanovesicles (LRNVs) are then synthesized at high yields using a facile, extrusion-based methodology. Evaluation of biological properties reveals that LRNVs can promote neurogenesis and angiogenesis through modulation of lipid raft-dependent signaling pathways. A proof-of-concept methodology further shows that LRNVs could be loaded with proteins or other bioactive cargo for greater disease-specific functionalities, thus presenting a novel type of biomimetic nanovesicles that can be leveraged as targeted therapeutics for regenerative medicine.

Engineering extracellular vesicles for Alzheimer's disease: An emerging cell-free approach for earlier diagnosis and treatment.

Alzheimer's disease (AD) is a debilitating neurodegenerative disorder affecting over five million people globally and has no established cure. Current AD-related treatments only alleviate cognitive and behavioral symptoms and do not address disease onset or progression, underlining the unmet need to create an effective, innovative AD therapeutic. Extracellular vesicles (EVs) have emerged as a new class of nanotherapeutics. These secreted, lipid-bound cellular signaling carriers show promise for potential clinical applications for neurodegenerative diseases like AD. Additionally, analyzing contents and characteristics of patient-derived EVs may address the unmet need for earlier AD diagnostic techniques, informing physicians of altered genetic expression or cellular communications specific to healthy and diseased physiological states. There are numerous recent advances in regenerative medicine using EVs and include bioengineering perspectives to modify EVs, target glial cells in neurodegenerative diseases like AD, and potentially use EVs to diagnose and treat AD earlier. This article is categorized under: Neurological Diseases > Biomedical Engineering Neurological Diseases > Molecular and Cellular Physiology Neurological Diseases > Stem Cells and Development.