Biology subjects

Feinberg, A. W.

Publications and source records attributed to Feinberg, A. W..

12 recordsLinked to original sources

bioRxiv2026

Multi-Modal photoFRESH: Light-Pipe Embedded Printing of Heterogeneous Hydrogel and Tissue Architectures

Recreating the complex spatial gradients and multi-material transitions of native tissues remains a fundamental challenge in 3D bioprinting. To address this, we introduce multi-modal photoFRESH, which integrates localized photochemistry into embedded printing by delivering light through a fiber-optic light-pipe. By tuning numerical aperture, print speed, and photoabsorber content, we achieve precise layer-by-layer control of crosslinking, stiffness, and bioorthogonal biomolecular tethering while preserving high print fidelity. Both photoactivatable support baths and extruded bioinks can be patterned, together with traditional FRESH printing. Utility of the platform is demonstrated by the fabrication of structurally complex tissue scaffolds and cellularized muscle constructs with distinct mechanical and biochemical domains. This multi-modal approach expands the boundaries of embedded bioprinting toward functional and heterogeneous tissue architectures.

bioengineering↗

bioRxiv2026

Early electrical stimulation promotes functional recovery after volumetric muscle loss

Volumetric muscle loss (VML) injuries overwhelm the inherent regenerative capacity of skeletal muscle, causing persistent functional deficits with no routinely effective therapies. Electrical stimulation (ES) has been shown to preserve muscle structure in other injury models, but technical barriers have prevented daily delivery during the acute post-injury window when critical regenerative programs are established. Here, we developed a fully implantable bioelectronic system with nanoporous platinum-modified electrodes enabling daily therapeutic stimulation and electromyographic recording without repeated anesthesia in a rat tibialis anterior VML model. Animals receiving ES during the acute post-injury period (10 sessions over days 0-14) showed sustained functional improvement, reaching 90% of baseline torque at 8 weeks compared to 71% in unstimulated controls. This recovery reflected enhanced remodeling of injured muscle rather than synergistic muscle compensation. Histological analysis revealed coordinated early increases in vascularization, pro-regenerative macrophages, and satellite cells. These findings establish early ES as a promising intervention for promoting muscle regeneration after catastrophic injury.

bioengineering↗

bioRxiv2025

Modular Assembly of Biohybrid Machines Using Force-Enhanced Skeletal Muscle Actuators

Muscle-based biohybrid systems integrate living muscle with engineered structures to create soft robots, biological models, and regenerative platforms. However, current actuators often lack strength and are difficult to assemble into complex devices. This study presents a suspended compliant skeleton that enhances muscle maturation by providing passive resistance, enabling high-stroke self-exercise without external stimulation. Using immortalized C2C12 cells, the resulting actuators achieved millimeter-scale strokes and millinewton-scale forces, surpassing previous benchmarks. Magnetic interfaces embedded in the skeleton allowed modular assembly into multi-degree-of-freedom devices such as grippers, arms, and positioning stages. These interfaces also support actuator replacement and repair, improving resilience and scalability. This approach significantly boosts engineered muscle performance and offers a robust, modular platform for building high-functioning, repairable biohybrid machines.

bioengineering↗

bioRxiv2025

Engineering 3D Skeletal Muscle Tissue with Complex Multipennate Myofiber Architectures

The hierarchical architecture of skeletal muscle spans from microscale sarcomeres to macroscale myofibers and is integral to its contractile functionality. Pathologies such as volumetric muscle loss (VML) compromise this structure and destroy the native extracellular matrix (ECM), exceeding the regenerative capacity of endogenous repair mechanisms. Here, we present a novel method for tissue engineering biomimetic three-dimensional (3D) skeletal muscle with complex architectures by leveraging freeform reversible embedding of suspended hydrogels (FRESH) 3D bioprinting of the ECM. Collagen type I scaffolds mimicking diverse muscle architectures-- including parallel, unipennate, bipennate, multipennate, and convergent--were designed, FRESH printed, and seeded with C2C12 myoblasts to guide myogenesis. Engineered muscle tissues demonstrated scaffold-mediated alignment and fusion into functional myotubes, exhibiting contractile responses to electrical stimulation with architecture-dependent specific force of [~]1 kN/m2 and a positive force-frequency relationship. In vivo implantation further revealed scaffold-directed cellular and vascular organization, underscoring the translational potential of this approach. In summary, this study demonstrates the capability to use FRESH 3D bioprinting to engineer physiologically relevant muscle architectures, significantly advancing the design of functional muscle tissues for regenerative medicine and in vitro modeling applications.

bioengineering↗

bioRxiv2024

Transient Notch Activation Converts Pluripotent Stem Cell-Derived Cardiomyocytes towards a Purkinje Fiber Fate

Cardiac Purkinje fibers form the most distal part of the ventricular conduction system. They coordinate contraction and play a key role in ventricular arrhythmias. While many cardiac cell types can be generated from human pluripotent stem cells, methods to generate Purkinje fiber cells remain limited, hampering our understanding of Purkinje fiber biology and conduction system defects. To identify signaling pathways involved in Purkinje fiber formation, we analyzed single cell data from murine embryonic hearts and compared Purkinje fiber cells to trabecular cardiomyocytes. This identified several genes, processes, and signaling pathways putatively involved in cardiac conduction, including Notch signaling. We next tested whether Notch activation could convert human pluripotent stem cell-derived cardiomyocytes to Purkinje fiber cells. Following Notch activation, cardiomyocytes adopted an elongated morphology and displayed altered electrophysiological properties including increases in conduction velocity, spike slope, and action potential duration, all characteristic features of Purkinje fiber cells. RNA-sequencing demonstrated that Notch-activated cardiomyocytes undergo a sequential transcriptome shift, which included upregulation of key Purkinje fiber marker genes involved in fast conduction such as SCN5A, HCN4 and ID2, and downregulation of genes involved in contractile maturation. Correspondingly, we demonstrate that Notch-induced cardiomyocytes have decreased contractile force in bioengineered tissues compared to control cardiomyocytes. We next modified existing in silico models of human pluripotent stem cell-derived cardiomyocytes using our transcriptomic data and modeled the effect of several anti-arrhythmogenic drugs on action potential and calcium transient waveforms. Our models predicted that Purkinje fiber cells respond more strongly to dofetilide and amiodarone, while cardiomyocytes are more sensitive to treatment with nifedipine. We validated these findings in vitro, demonstrating that our new cell-specific in vitro model can be utilized to better understand human Purkinje fiber physiology and its relevance to disease.

developmental biology↗

bioRxiv2024

3D Bioprinting of Collagen-based Microfluidics for Engineering Fully-biologic Tissue Systems

Microfluidic and organ-on-a-chip devices have improved the physiologic and translational relevance of in vitro systems in applications ranging from disease modeling to drug discovery and pharmacology. However, current manufacturing approaches have limitations in terms of materials used, non-native mechanical properties, patterning of extracellular matrix (ECM) and cells in 3D, and remodeling by cells into more complex tissues. We present a method to 3D bioprint ECM and cells into microfluidic collagen-based high-resolution internally perfusable scaffolds (CHIPS) that address these limitations, expand design complexity, and simplify fabrication. Additionally, CHIPS enable size-dependent diffusion of molecules out of perfusable channels into the surrounding device to support cell migration and remodeling, formation of capillary-like networks, and integration of secretory cell types to form a glucose-responsive, insulin-secreting pancreatic-like microphysiological system. One-Sentence SummaryMulti-material FRESH 3D bioprinting of microfluidic CHIPS to generate fully biologic centimeter-scale and vascularized pancreatic-like tissue systems.

bioengineering↗

bioRxiv2022

Development of a High-Performance Open-Source 3D Bioprinter

The application of 3D printing to biological research has provided the tissue engineering community with a method for organizing cells and biological materials into complex 3D structures. While many commercial bioprinting platforms exist, they are expensive, ranging from $5,000 to over $500,000. This high cost of entry prevents many labs from incorporating 3D bioprinting into their research. Due to the open-source nature of desktop plastic 3D printers, an alternative option has been to convert low-cost plastic printers into bioprinters. Several open-source modifications have been described, but there remains a need for a user-friendly, step-by-step guide for converting a thermoplastic printer into a bioprinter using components with validated performance. Here we convert a low-cost 3D printer, the FlashForge Finder, into a bioprinter using our Replistruder 4 syringe pump and the Duet3D Duet 2 WiFi for total cost of less than $900. We demonstrate that the accuracy of the bioprinters travel is better than 35 {micro}m in all three axes, and quantify fidelity by printing square lattice collagen scaffolds with average errors less than 2%. We also show high fidelity reproduction of clinical-imaging data by printing a scaffold of a human ear using collagen bioink. Finally, to maximize accessibility and customizability, all components we have designed for the bioprinter conversion are provided as open-source 3D models, along with instructions for further modifying the bioprinter for additional use cases, resulting in a comprehensive guide for the bioprinting field.

bioengineering↗

bioRxiv2021

In Situ Volumetric Imaging and Analysis of FRESH 3D Bioprinted Constructs Using Optical Coherence Tomography

As 3D bioprinting has grown as a fabrication technology, so too has the need for improved analytical methods to characterize these engineered constructs. This is especially challenging for soft tissues composed of hydrogels and cells as these materials readily deform, posing a barrier when trying to assess print fidelity and other properties non- destructively. Indeed, given the importance of structure-function relationships in most tissue types, establishing that the 3D architecture of the bioprinted construct matches its intended anatomic design is critical. Here we report development of a multimaterial bioprinting platform with integrated optical coherence tomography (OCT) for in situ volumetric imaging, error detection, and 3D reconstruction. While generally applicable to extrusion-based 3D bioprinting, we also report improvements to the Freeform Reversible Embedding of Suspended Hydrogels (FRESH) bioprinting process through new collagen bioink compositions, support bath optical clearing, and machine pathing. This enables high-fidelity 3D volumetric imaging with micron scale resolution over centimeter length scales, the ability to detect a range of print defect types within a 3D volume, and real-time imaging of the printing process at each print layer. These advances provide FRESH and other extrusion-based 3D bioprinting approaches with a comprehensive methodology for quality assessment that has been absent in the field to date, paving the way for translation of these engineered tissues to the clinic and ultimately to achieving regulatory approval. TeaserTransparent FRESH support bath enables in situ 3D volumetric imaging and validation of patient-derived tissue constructs.

bioengineering↗

bioRxiv2021

Recapitulate Human Cardio-pulmonary Co-development Using Simultaneous Multilineage Differentiation of Pluripotent Stem Cells

The extensive crosstalk between the developing heart and lung is pivotal for their proper morphogenesis and maturation. However, there remains a lack of model systems for investigating the critical cardio-pulmonary mutual interaction during human embryogenesis. Here, we reported a novel stepwise strategy for directing simultaneous induction of both mesoderm-derived cardiac and endoderm-derived lung epithelial lineages within a single differentiation of human pluripotent stem cells (hPSCs) via temporal specific tuning of WNT and TGF-{beta} signaling in the absence of exogenous growth factors. Using 3D suspension culture, we established concentric cardio-pulmonary micro-Tissues (Ts), and observed expedited alveolar maturation in the presence of cardiac accompany. Upon withdrawal of WNT agonist, the cardiac and pulmonary components within each dual-lineage T effectively segregated from each other with concurrent initiation of cardiac contraction. We expect our multilineage differentiation model to offer an experimentally tractable system for investigating human cardio-pulmonary interplay and tissue boundary formation during embryogenesis.

developmental biology↗

bioRxiv2021

Injury-Free In Vivo Delivery and Engraftment into the Cornea Endothelium Using Extracellular Matrix Shrink-Wrapped Cells

Cell injection is a common clinical approach for therapeutic delivery of cells into diseased and damaged tissues in order to achieve regeneration. However, cell retention, viability, and engraftment at the injection site has generally been poor, driving the need for improved approaches. Here, we developed a technique to shrink-wrap micropatterned islands of corneal endothelial cells in a basement membrane-like layer of extracellular matrix (ECM) that enables the cells to maintain their cell-cell junctions and cytoskeletal structure while in suspension. These Monolayers exhibited the ability to rapidly engraft into intact, high-density corneal endothelial monolayers in both in vitro and in vivo model systems. Importantly, the engrafted Monolayers increased local cell density, something that the clinical-standard single cells in suspension failed to do. These results show that shrink-wrapping cells in ECM dramatically improves engraftment and provides a potential alternative to cornea transplant when low endothelial cell density is the cause of corneal blindness. One Sentence SummaryShrink-wrapped patches of endothelial cells can rapidly attach and integrate into an intact cornea endothelium when injected into the anterior chamber, increasing cell density.

bioengineering↗

bioRxiv2020

Dynamic Loading of Human Engineered Heart Tissue Enhances Contractile Function and Drives Desmosome-linked Disease Phenotype

The role mechanical forces play in shaping the structure and function of the heart is critical to understanding heart formation and the etiology of disease but is challenging to study in patients. Engineered heart tissues (EHTs) incorporating human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes have the potential to provide insight into these adaptive and maladaptive changes in the heart. However, most EHT systems are unable to model both preload (stretch during chamber filling) and afterload (pressure the heart must work against to eject blood). Here, we have developed a new dynamic EHT (dyn-EHT) model that enables us to tune preload and have unconstrained fractional shortening of >10%. To do this, 3D EHTs are integrated with an elastic polydimethylsiloxane (PDMS) strip that provides mechanical pre- and afterload to the tissue in addition to enabling contractile force measurements based on strip bending. Our results demonstrate in wild-type EHTs that dynamic loading is beneficial based on the magnitude of the forces, leading to improved alignment, conduction velocity, and contractility. For disease modeling, we use hiPSC-derived cardiomyocytes from a patient with arrhythmogenic cardiomyopathy (ACM) due to mutations in desmoplakin. We demonstrate that manifestation of this desmosome-linked disease state requires the dyn-EHT conditioning and that it cannot be induced using 2D or standard 3D EHT approaches. Thus, dynamic loading strategy is necessary to provoke a disease phenotype (diastolic lengthening, reduction of desmosome counts, and reduced contractility), which are akin to primary endpoints of clinical disease, such as chamber thinning and reduced cardiac output. Single Sentence SummaryDevelopment of a dynamic mechanical loading platform to improve contractile function of engineered heart tissues and study cardiac disease progression.

bioengineering↗

bioRxiv2020

Fibronectin-Based Nanomechanical Biosensors to Map 3D Strains in Live Cells and Tissues

Mechanical forces are integral to a wide range of cellular processes including migration, differentiation and tissue morphogenesis; however, it has proved challenging to directly measure strain at high spatial resolution and with minimal tissue perturbation. Here, we fabricated, calibrated, and tested a fibronectin (FN)-based nanomechanical biosensor (NMBS) that can be applied to cells and tissues to measure the magnitude, direction, and dynamics of strain from subcellular to tissue length-scales. The NMBS is a fluorescently-labeled, ultrathin square lattice FN mesh with spatial resolution tailored by adjusting the width and spacing of the lattice fibers from 2-100 {micro}m. Time-lapse 3D confocal imaging of the NMBS demonstrated strain tracking in 2D and 3D following mechanical deformation of known materials and was validated with finite element modeling. Imaging and 3D analysis of the NMBS applied to single cells, cell monolayers, and Drosophila ovarioles demonstrated the ability to dynamically track microscopic tensile and compressive strains in various biological applications with minimal tissue perturbation. This fabrication and analysis platform serves as a novel tool for studying cells, tissues, and more complex systems where forces guide structure and function.

bioengineering↗