Bioinspired Oligo-Urethane Nanoparticles for Delivering Exogenous C-Type Natriuretic Peptide: Synthetic Biomaterial Nanocarrier Complexes and Their Interactions with Cardiac Myofibroblasts.

In a healthy heart, cells naturally secrete C-type natriuretic peptide (CNP), a cytokine that protects against myofibroblast differentiation of cardiac fibroblasts and extracellular matrix deposition leading to fibrosis. CNP availability during myocardial remodeling is important to prevent cardiac fibrosis, but CNP is limited after an injury because of the loss of cardiomyocytes and the activation of cardiac fibroblasts to myofibroblasts. We hypothesized that the sustained release of exogenous CNP from oligo-urethane nanoparticles (NPs) would reduce differentiation of human cardiac fibroblasts toward a myofibrogenic phenotype. Our work used a modified form of a degradable polar hydrophobic ionic (D-PHI) oligo-urethane, which has shown the ability to self-assemble into NPs for the delivery of peptide and oligonucleotide biomolecules. The CNP-loaded NPs (NPCNP) were characterized for a diameter of 129 ± 1.4 nm and a ζ potential of -46 ± 7.8 mV. Treatment of cardiac fibroblasts with NPCNP increased cyclic guanosine-monophosphate (cGMP) synthesis, confirming that exogenous CNP delivered via oligo-urethane NPs is bioactive and can induce downstream signaling that has been implicated in antagonizing transforming growth factor-ß1 (TGF-ß1)-induced myofibrogenic differentiation. It is also shown that treatment with NPCNP attenuated contraction of collagen gels by cardiac myofibroblasts stimulated with TGF-ß1. Coating with heparin on the NPCNP (HEP-NPCNP) exemplified an approach to extend the release of CNP from the NPs. Both HEP-NPCNP and NPCNP show minimal cell toxicity, studied up to 0.25 × 1010 NPs/mL in culture media. These findings support further investigation of CNP delivery via NPs as a future therapy for suppressing cardiac fibrosis.

Bioprinting technologies for disease modeling.

There is a great need for the development of biomimetic human tissue models that allow elucidation of the pathophysiological conditions involved in disease initiation and progression. Conventional two-dimensional (2D) in vitro assays and animal models have been unable to fully recapitulate the critical characteristics of human physiology. Alternatively, three-dimensional (3D) tissue models are often developed in a low-throughput manner and lack crucial native-like architecture. The recent emergence of bioprinting technologies has enabled creating 3D tissue models that address the critical challenges of conventional in vitro assays through the development of custom bioinks and patient derived cells coupled with well-defined arrangements of biomaterials. Here, we provide an overview on the technological aspects of 3D bioprinting technique and discuss how the development of bioprinted tissue models have propelled our understanding of diseases' characteristics (i.e. initiation and progression). The future perspectives on the use of bioprinted 3D tissue models for drug discovery application are also highlighted.

Characterization of pediatric porcine pulmonary valves as a model for tissue engineered heart valves.

Heart valve tissue engineering holds the potential to transform the surgical management of congenital heart defects affecting the pediatric pulmonary valve (PV) by offering a viable valve replacement. While aiming to recapitulate the native valve, the minimum requirement for tissue engineered heart valves (TEHVs) has historically been adequate mechanical function at implantation. However, long-term in situ functionality of TEHVs remains elusive, suggesting that a closer approximation of the native valve is required. The realization of biomimetic engineered pediatric PV is impeded by insufficient characterization of healthy pediatric tissue. In this study, we comprehensively characterized the planar biaxial tensile behaviour, extracellular matrix (ECM) composition and organization, and valvular interstitial cell (VIC) phenotypes of PVs from piglets to provide benchmarks for TEHVs. The piglet PV possessed an anisotropic and non-linear tension-strain profile from which material constants for a predictive constitutive model were derived. The ECM of the piglet PV possessed a trilayer organization populated by collagen, glycosaminoglycans, and elastin. Biochemical quantification of ECM content normalized to wet weight and DNA content of PV tissue revealed homogeneous distribution across sampled regions of the leaflet. Finally, VICs in the piglet PV were primarily quiescent vimentin-expressing fibroblasts, with a small proportion of activated α-smooth muscle actin-expressing myofibroblasts. Overall, piglet PV properties were consistent with those reported anecdotally for pediatric human PVs and distinct from those of adult porcine and human PVs, supporting the utility of the properties determined here to inform the design of tissue engineered pediatric PVs. STATEMENT OF SIGNIFICANCE: Heart valve tissue engineering has the potential to transform treatment for children born with defective pulmonary valves by providing living replacement tissue that can grow with the child. The design of tissue engineered heart valves is best informed by native valve properties, but native pediatric pulmonary valves have not been fully described to date. Here, we provide comprehensive characterization of the planar biaxial tensile behaviour, extracellular matrix composition and organization, and valvular interstitial cell phenotypes of pulmonary valves from piglets as a model for the native human pediatric valve. Together, these findings provide standards that inform engineered heart valve design towards generation of biomimetic pediatric pulmonary valves.

High-frequency quantitative ultrasound for the assessment of the acoustic properties of engineered tissues in vitro.

Acoustic properties of biomaterials and engineered tissues reflect their structure and cellularity. High-frequency ultrasound (US) can non-invasively characterize and monitor these properties with sub-millimetre resolution. We present an approach to estimate the speed of sound, acoustic impedance, and acoustic attenuation of cell-laden hydrogels that accounts for frequency-dependent effects of attenuation in coupling media, hydrogel thickness, and interfacial transmission/reflection coefficients of US waves, all of which can bias attenuation estimates. Cell-seeded fibrin hydrogel disks were raster-scanned using a 40 MHz US transducer. Thickness, speed of sound, acoustic impedance, and acoustic attenuation coefficients were determined from the difference in the time-of-flight and ratios of the magnitudes of US signals, interfacial transmission/reflection coefficients, and acoustic properties of the coupling media. With this approach, hydrogel thickness was accurately measured by US, with agreement to confocal microscopy (r2 = 0.97). Accurate thickness measurement enabled acoustic property measurements that were independent of hydrogel thickness, despite up to 60% reduction in thickness due to cell-mediated contraction. Notably, acoustic attenuation coefficients increased with increasing cell concentration (p < 0.001), reflecting hydrogel cellularity independent of contracted hydrogel thickness. This approach enables accurate measurement of the intrinsic acoustic properties of biomaterials and engineered tissues to provide new insights into their structure and cellularity. STATEMENT OF SIGNIFICANCE: High-frequency ultrasound can measure the acoustic properties of engineered tissues non-invasively and non-destructively with µm-scale resolution. Acoustic properties, including acoustic attenuation, are related to intrinsic material properties, such as scatterer density. We developed an analytical approach to estimate the acoustic properties of cell-laden hydrogels that accounts for the frequency-dependent effects of attenuation in coupling media, the reflection/transmission of ultrasound waves at the coupling interfaces, and the dependency of measurements on hydrogel thickness. Despite up to 60% reduction in hydrogel thickness due to cell-mediated contraction, our approach enabled measurements of acoustic properties that were substantially independent of thickness. Acoustic attenuation increased significantly with increasing cell concentration (p < 0.001), demonstrating the ability of acoustic attenuation to reflect intrinsic physical properties of engineered tissues.

Smart Dual-Sensor Wound Dressing for Monitoring Cutaneous Wounds.

Managing slow-healing wounds and associated complications is challenging, time-consuming, and expensive. Systematic collection, analysis, and dissemination of correct wound status data are critical for enhancing healing outcomes and reducing complications. However, traditional data collection approaches are often neither accurate nor user-friendly and require diverse skill levels, resulting in the collection of inconsistent and unreliable data. As an advancement to the authors' previously developed hydrogel-based smart wound dressing, here is reported an enhanced integration of drug delivery and sensing (pH and glucose) modules for accelerated treatment and continuous monitoring of cutaneous wounds. In the current study, growth factor delivery modules and an array of colorimetric glucose sensors are incorporated into the dressing to promote wound healing and extend the dressing's utility for diabetic wound treatment. Furthermore, the efficacy of the wound dressing in monitoring infection and supporting wound healing via antibiotic and growth factor delivery is investigated in mice models. The updated dressing reveals excellent healing benefits on non-infected and infected wounds, as well as real-time monitoring and early detection of wound infection.

Serum- and xeno-free culture of human umbilical cord perivascular cells for pediatric heart valve tissue engineering.

BACKGROUND: Constructs currently used to repair or replace congenitally diseased pediatric heart valves lack a viable cell population capable of functional adaptation in situ, necessitating repeated surgical intervention. Heart valve tissue engineering (HVTE) can address these limitations by producing functional living tissue in vitro that holds the potential for somatic growth and remodelling upon implantation. However, clinical translation of HVTE strategies requires an appropriate source of autologous cells that can be non-invasively harvested from mesenchymal stem cell (MSC)-rich tissues and cultured under serum- and xeno-free conditions. To this end, we evaluated human umbilical cord perivascular cells (hUCPVCs) as a promising cell source for in vitro production of engineered heart valve tissue. METHODS: The proliferative, clonogenic, multilineage differentiation, and extracellular matrix (ECM) synthesis capacities of hUCPVCs were evaluated in a commercial serum- and xeno-free culture medium (StemMACS™) on tissue culture polystyrene and benchmarked to adult bone marrow-derived MSCs (BMMSCs). Additionally, the ECM synthesis potential of hUCPVCs was evaluated when cultured on polycarbonate polyurethane anisotropic electrospun scaffolds, a representative biomaterial for in vitro HVTE. RESULTS: hUCPVCs had greater proliferative and clonogenic potential than BMMSCs in StemMACS™ (p < 0.05), without differentiation to osteogenic and adipogenic phenotypes associated with valve pathology. Furthermore, hUCPVCs cultured with StemMACS™ on tissue culture plastic for 14 days synthesized significantly more total collagen, elastin, and sulphated glycosaminoglycans (p < 0.05), the ECM constituents of the native valve, than BMMSCs. Finally, hUCPVCs retained their ECM synthesizing capacity after 14 and 21 days in culture on anisotropic electrospun scaffolds. CONCLUSION: Overall, our findings establish an in vitro culture platform that uses hUCPVCs as a readily-available and non-invasively sourced autologous cell population and a commercial serum- and xeno-free culture medium to increase the translational potential of future pediatric HVTE strategies. This study evaluated the proliferative, differentiation and extracellular matrix (ECM) synthesis capacities of human umbilical cord perivascular cells (hUCPVCs) when cultured in serum- and xeno-free media (SFM) against conventionally used bone marrow-derived MSCs (BMMSCs) and serum-containing media (SCM). Our findings support the use of hUCPVCs and SFM for in vitro heart valve tissue engineering (HVTE) of autologous pediatric valve tissue. Figure created with BioRender.com.

Recent Progress Toward Clinical Translation of Tissue-Engineered Heart Valves.

Surgical replacement remains the primary option to treat the rapidly growing number of patients with severe valvular heart disease. Although current valve replacements-mechanical, bioprosthetic, and cryopreserved homograft valves-enhance survival and quality of life for many patients, the ideal prosthetic heart valve that is abundantly available, immunocompatible, and capable of growth, self-repair, and life-long performance has yet to be developed. These features are essential for pediatric patients with congenital defects, children and young adult patients with rheumatic fever, and active adult patients with valve disease. Heart valve tissue engineering promises to address these needs by providing living valve replacements that function similarly to their native counterparts. This is best evidenced by the long-term clinical success of decellularised pulmonary and aortic homografts, but the supply of homografts cannot meet the demand for replacement valves. A more abundant and consistent source of replacement valves may come from cellularised valves grown in vitro or acellular off-the-shelf biomaterial/tissue constructs that recellularise in situ, but neither tissue engineering approach has yet achieved long-term success in preclinical testing. Beyond the technical challenges, heart valve tissue engineering faces logistical, economic, and regulatory challenges. In this review, we summarise recent progress in heart valve tissue engineering, highlight important outcomes from preclinical and clinical testing, and discuss challenges and future directions toward clinical translation.

Microfluidic 3D Printing of a Photo-Cross-Linkable Bioink Using Insights from Computational Modeling.

Three-dimensional (3D) bioprinting of photo-cross-linkable hydrogel precursors has attracted great interest in various tissue engineering and drug screening applications, as the biochemical and biophysical properties of the resultant hydrogel structures can be tuned spatiotemporally to provide cells with physiologically relevant microenvironments. In particular, these bioinks benefit from great biofunctional versatility that can be designed to direct cells toward a desired behavior. Despite significant progress in the field, the 3D printing of cell-laden photo-cross-linkable bioinks with low polymer concentrations has remained a challenge, as rapidly stabilizing these bioinks and transforming them to hydrogel filaments is hindered by their low viscosity. Additionally, reaching an optimized print condition has often been challenging due to the large number of print parameters involved in 3D bioprinting setups. Therefore, computational modeling has occasionally been employed to understand the impact of various print parameters and reduce the time and resources required to determine these effects in experimental settings. Here, we report a novel 3D bioprinting strategy for fabricating hydrogel fibrous structures of gelatin methacryloyl (GelMA) with superior control over polymer concentration, particularly in a relatively low range from ∼1% (w/v) to 6% (w/v), using a microfluidic printhead. The printhead features a coaxial core-sheath flow, coupled with a photo-cross-linking system, allowing for the in situ cross-linking of GelMA and the generation of hydrogel filaments. A computational model was developed to determine the optimal ranges of process parameters and inform about the diffusive and fluid dynamic behavior of the coaxial flow. The cytocompatibility of the biofabrication system was determined via bioprinting cell-laden bioinks containing U87-MG cells. Notably, the established pipeline from computational modeling to bioprinting has great potential to be applied to a wide range of photo-cross-linkable bioinks to generate living tissues with various material and cellular characteristics.

Management of Coronavirus Disease 2019 (COVID-19) Pandemic: From Diagnosis to Treatment Strategies.

Following the emergence of severe acute respiratory syndrome (SARS) in 2002 and the Middle East respiratory syndrome (MERS) in 2012, the world is now combating a third large-scale outbreak caused by a coronavirus, the coronavirus disease 2019 (COVID-19). After the rapid spread of SARS-coronavirus (CoV)-2 (the virus causing COVID-19) from its origin in China, the World Health Organization (WHO) declared a Public Health Emergency of International Concern (PHEIC) on January 30, 2020. From the beginning of the COVID-19 pandemic, a significant number of studies have been conducted to better understand the biology and pathogenesis of the novel coronavirus, and to aid in developing effective treatment regimens, therapeutics, and vaccines. This review focuses on the recent advancements in the rapidly evolving areas of clinical care and management of COVID-19. The emerging strategies for the diagnosis and treatment of this disease are explored, and the development of effective vaccines is reviewed.

Facile Method for Fabrication of Meter-Long Multifunctional Hydrogel Fibers with Controllable Biophysical and Biochemical Features.

Hydrogel structures with microscale morphological features have extensive application in tissue engineering owing to their capacity to induce desired cellular behavior. Herein, we describe a novel biofabrication method for fabrication of grooved solid and hollow hydrogel fibers with control over their cross-sectional shape, surface morphology, porosity, and material composition. These fibers were further configured into three-dimensional structures using textile technologies such as weaving, braiding, and embroidering methods. Additionally, the capacity of these fibers to integrate various biochemical and biophysical cues was shown via incorporating drug-loaded microspheres, conductive materials, and magnetic particles, extending their application to smart drug delivery, wearable or implantable medical devices, and soft robotics. The efficacy of the grooved fibers to induce cellular alignment was evaluated on various cell types including myoblasts, cardiomyocytes, cardiac fibroblasts, and glioma cells. In particular, these fibers were shown to induce controlled myogenic differentiation and morphological changes, depending on their groove size, in C2C12 myoblasts.

A 3D bioprinted hydrogel mesh loaded with all-trans retinoic acid for treatment of glioblastoma.

Treatment of glioblastoma (GBM), as the most lethal type of brain tumor, still remains a major challenge despite the various therapeutic approaches developed over the recent decades. GBM is considered as one of the most therapy-resistant human tumors. Treatment with temozolomide (TMZ) chemotherapy and radiotherapy in GBM patients has led to 30% of two-year survival rate (American Brain Tumor Association), representing a demanding field to develop more effective therapeutic strategies. This study presents a novel method for local delivery of all-trans retinoic acid (ATRA) for targeting GBM cells as a possible adjuvant therapeutic strategy for this disease. We have used 3D bioprinting to fabricate hydrogel meshes laden with ATRA-loaded polymeric particles. The ATRA-loaded meshes have been shown to facilitate a sustained release of ATRA with tunable release rate. Cell viability assay was used to demonstrate the ability of fabricated meshes in reducing cell growth in U-87 MG cell line. We later showed that the developed meshes induced apoptotic cell death in U-87 MG. Furthermore, the use of hydrogel for embedding the ATRA-loaded particles can facilitate the immobilization of the drug next to the tumor site. Our current innovative approach has shown the potential to open up new avenues for treatment of GBM, benefiting patients who suffer from this debilitating disease.

Blending Electronics with the Human Body: A Pathway toward a Cybernetic Future.

At the crossroads of chemistry, electronics, mechanical engineering, polymer science, biology, tissue engineering, computer science, and materials science, electrical devices are currently being engineered that blend directly within organs and tissues. These sophisticated devices are mediators, recorders, and stimulators of electricity with the capacity to monitor important electrophysiological events, replace disabled body parts, or even stimulate tissues to overcome their current limitations. They are therefore capable of leading humanity forward into the age of cyborgs, a time in which human biology can be hacked at will to yield beings with abilities beyond their natural capabilities. The resulting advances have been made possible by the emergence of conformal and soft electronic materials that can readily integrate with the curvilinear, dynamic, delicate, and flexible human body. This article discusses the recent rapid pace of development in the field of cybernetics with special emphasis on the important role that flexible and electrically active materials have played therein.

An Advanced Multifunctional Hydrogel-Based Dressing for Wound Monitoring and Drug Delivery.

Wound management is a major global challenge and poses a significant financial burden to the healthcare system due to the rapid growth of chronic diseases such as diabetes, obesity, and aging population. The ability to detect pathogenic infections and release drug at the wound site is of the utmost importance to expedient patient care. Herein, this study presents an advanced multifunctional dressing (GelDerm) capable of colorimetric measurement of pH, an indicator of bacterial infection, and release of antibiotic agents at the wound site. This study demonstrates the ability of GelDerm to detect bacterial infections using in vitro and ex vivo tests with accuracies comparable to the commercially available systems. Wireless interfaces to digital image capture hardware such as smartphones serve as a means for quantitation and enable the patient to record the wound condition at home and relay the information to the healthcare personnel for following treatment strategies. Additionally, the dressing is integrated within commercially available patches and can be placed on the wound without chemical or physical irritation. This study demonstrates the ability of GelDerm to eradicate bacteria by the sustained release of antibiotics. The proposed technology holds great promise in managing chronic and acute injuries caused by trauma, surgery, or diabetes.

Emerging Biofabrication Strategies for Engineering Complex Tissue Constructs.

The demand for organ transplantation and repair, coupled with a shortage of available donors, poses an urgent clinical need for the development of innovative treatment strategies for long-term repair and regeneration of injured or diseased tissues and organs. Bioengineering organs, by growing patient-derived cells in biomaterial scaffolds in the presence of pertinent physicochemical signals, provides a promising solution to meet this demand. However, recapitulating the structural and cytoarchitectural complexities of native tissues in vitro remains a significant challenge to be addressed. Through tremendous efforts over the past decade, several innovative biofabrication strategies have been developed to overcome these challenges. This review highlights recent work on emerging three-dimensional bioprinting and textile techniques, compares the advantages and shortcomings of these approaches, outlines the use of common biomaterials and advanced hybrid scaffolds, and describes several design considerations including the structural, physical, biological, and economical parameters that are crucial for the fabrication of functional, complex, engineered tissues. Finally, the applications of these biofabrication strategies in neural, skin, connective, and muscle tissue engineering are explored.