Adopt-A-Classroom Program: A Potential Platform to Address the Root of Health Disparities in the US

The underrepresentation of Black doctors is a significant issue in the US that led to the perpetuation of health disparities in the African American community. Racial and ethnic minorities in the US have been shown to have higher rates of chronic diseases, such as hypertension, diabetes, and cardiovascular disease, as well as higher rates of obesity and premature death compared to White people. While Blacks make up more than 13% of the US population, they comprise only 4% of US doctors and less than 7% of medical students. It is believed that this problem requires more deliberate efforts by policymakers and the educational establishment, not only at the undergraduate and medical school level, but earlier in the educational "pipeline"-the K-12 school system. While the medical field is rooted in Science, Technology, Engineering, and Mathematics (STEM), we have launched a new initiative that will provide year-round STEM development activities for K-12 education in Connecticut in Hartford and Waterbury districts, especially among populations with health disparities.

Development of porcine skeletal muscle extracellular matrix-derived hydrogels with improved properties and low immunogenicity

Hydrogels derived from decellularized extracellular matrices (ECM) of animal origin show immense potential for regenerative applications due to their excellent cytocompatibility and biomimetic properties. Despite these benefits, the impact of decellularization protocols on the properties and immunogenicity of these hydrogels remains relatively unexplored. In this study, porcine skeletal muscle ECM (smECM) underwent decellularization using mechanical disruption (MD) and two commonly employed decellularization detergents, sodium deoxycholate (SDC) or Triton X-100. To mitigate immunogenicity associated with animal-derived ECM, all decellularized tissues were enzymatically treated with α-galactosidase to cleave the primary xenoantigen-the α-Gal antigen. Subsequently, the impact of the different decellularization protocols on the resultant hydrogels was thoroughly investigated. All methods significantly reduced total DNA content in hydrogels. Moreover, α-galactosidase treatment was crucial for cleaving α-Gal antigens, suggesting that conventional decellularization methods alone are insufficient. MD preserved total protein, collagen, sulfated glycosaminoglycan, laminin, fibronectin, and growth factors more efficiently than other protocols. The decellularization method impacted hydrogel gelation kinetics and ultrastructure, as confirmed by turbidimetric and scanning electron microscopy analyses. MD hydrogels demonstrated high cytocompatibility, supporting satellite stem cell recruitment, growth, and differentiation into multinucleated myofibers. In contrast, the SDC and Triton X-100 protocols exhibited cytotoxicity. Comprehensive in vivo immunogenicity assessments in a subcutaneous xenotransplantation model revealed MD hydrogels' biocompatibility and low immunogenicity. These findings highlight the significant influence of the decellularization protocol on hydrogel properties. Our results suggest that combining MD with α-galactosidase treatment is an efficient method for preparing low-immunogenic smECM-derived hydrogels with enhanced properties for skeletal muscle regenerative engineering and clinical applications.

Grand Challenges at the Interface of Engineering and Medicine

Over the past two decades Biomedical Engineering has emerged as a major discipline that bridges societal needs of human health care with the development of novel technologies. Every medical institution is now equipped at varying degrees of sophistication with the ability to monitor human health in both non-invasive and invasive modes. The multiple scales at which human physiology can be interrogated provide a profound perspective on health and disease. We are at the nexus of creating "avatars" (herein defined as an extension of "digital twins") of human patho/physiology to serve as paradigms for interrogation and potential intervention. Motivated by the emergence of these new capabilities, the IEEE Engineering in Medicine and Biology Society, the Departments of Biomedical Engineering at Johns Hopkins University and Bioengineering at University of California at San Diego sponsored an interdisciplinary workshop to define the grand challenges that face biomedical engineering and the mechanisms to address these challenges. The Workshop identified five grand challenges with cross-cutting themes and provided a roadmap for new technologies, identified new training needs, and defined the types of interdisciplinary teams needed for addressing these challenges. The themes presented in this paper include: 1) accumedicine through creation of avatars of cells, tissues, organs and whole human; 2) development of smart and responsive devices for human function augmentation; 3) exocortical technologies to understand brain function and treat neuropathologies; 4) the development of approaches to harness the human immune system for health and wellness; and 5) new strategies to engineer genomes and cells.

Fibroblast growth factor 8b (FGF-8b) enhances myogenesis and inhibits adipogenesis in rotator cuff muscle cell populations in vitro

Fatty expansion is one of the features of muscle degeneration due to muscle injuries, and its presence interferes with muscle regeneration. Specifically, poor clinical outcomes have been linked to fatty expansion in rotator cuff tears and repairs. Our group recently found that fibroblast growth factor 8b (FGF-8b) inhibits adipogenic differentiation and promotes myofiber formation of mesenchymal stem cells in vitro. This led us to hypothesize that FGF-8b could similarly control the fate of muscle-specific cell populations derived from rotator cuff muscle involved in muscle repair following rotator cuff injury. In this study, we isolate fibro-adipogenic progenitor cells (FAPs) and satellite stem cells (SCs) from rat rotator cuff muscle tissue and analyzed the effects of FGF-8b supplementation. Utilizing a cell plating protocol, we successfully isolate FAPs-rich fibroblasts (FIBs) and SCs-rich muscle progenitor cells (MPCs). Subsequently, we demonstrate that FIB adipogenic differentiation can be inhibited by FGF-8b, while MPC myogenic differentiation can be enhanced by FGF-8b. We further demonstrate that phosphorylated ERK due to FGF-8b leads to the inhibition of adipogenesis in FIBs and SCs maintenance and myofiber formation in MPCs. Together, these findings demonstrate the powerful potential of FGF-8b for rotator cuff repair by altering the fate of muscle undergoing degeneration.

The Shift: COVID-19-Associated Deaths are Now Trending Lower Among Blacks and Hispanics Compared to Whites

BACKGROUND

Throughout the coronavirus (COVID-19) pandemic, research revealed people of color were more likely to be infected, have severe illness, and die due to the virus. However, some areas in the USA are now reporting a new shift; lower Black and Hispanic COVID-19 mortality rates compared to their White counterparts. Research indicates that this shift is the result of COVID-19's impact on disparities by race. In this paper, we analyze death data to determine if the new shift has occurred locally. Specifically, we examined COVID-19 prevalence and related death data in Connecticut by comparing race/ethnicity through two periods of time: one before and one after the first case of the Omicron variant of COVID-19.

METHODS

This cross-sectional epidemiological analysis to examine cases and deaths by racial/ethnic status utilizes Connecticut data from March 2020 to February 2022. The following assumption is applied: expected pre-Omicron cases and deaths from March 5, 2020 to November 27, 2021 are equal to the number of cases and deaths during Omicron cases and deaths from November 28, 2021 to February 17, 2022. Race/ethnicity are operationalized as non-Hispanic White, non-Hispanic Black, and Hispanic.

RESULTS

Pre-Omicron (March 5, 2020 to November 27, 2021) compared to the monthly aged adjusted COVID-19 case rate for Whites (394/10,000 populations), Blacks had a higher rate (501/10,000 populations), and Hispanics had the highest (585/10,000 populations). During the Omicron period (November 28 to February 17, 2022), significant changes in COVID-19 case rates were observed in all three ethnic groups, but the biggest changes were observed in Hispanics, followed by Blacks, and then Whites. The rate ratios further showed a remarkable reduction of 47% in case rates (from 1.0 pre-Omicron and from 1.47 during Omicron, p < 0.0001) for Hispanics, when compared to that of Whites. While Blacks showed a significant, smaller reduction of 5% in case rates (from 1.27 pre-Omicron and from 1.22 during the Omicron, p < 0.001) when compared to Whites. Regarding COVID-19-related mortality, the racial differences were similar.

CONCLUSIONS AND RELEVANCE

By examining Connecticut's COVID-19 death and case data, this study identified the new shift that occurred locally. The current shift may be anchored in the evolution of the COVID-19 virus, public health guidelines/policies, and the degree to which populations have complied with public health recommendations.

Electroconductivity, a regenerative engineering approach to reverse rotator cuff muscle degeneration

Muscle degeneration is one the main factors that lead to the high rate of retear after a successful repair of rotator cuff (RC) tears. The current surgical practices have failed to treat patients with chronic massive rotator cuff tears (RCTs). Therefore, regenerative engineering approaches are being studied to address the challenges. Recent studies showed the promising outcomes of electroactive materials (EAMs) on the regeneration of electrically excitable tissues such as skeletal muscle. Here, we review the most important biological mechanism of RC muscle degeneration. Further, the review covers the recent studies on EAMs for muscle regeneration including RC muscle. Finally, we will discuss the future direction toward the application of EAMs for the augmentation of RCTs.

Hyaluronic acid-British anti-Lewisite as a safer chelation therapy for the treatment of arthroplasty-related metallosis

Cobalt-containing alloys are useful for orthopedic applications due to their low volumetric wear rates, corrosion resistance, high mechanical strength, hardness, and fatigue resistance. Unfortunately, these prosthetics release significant levels of cobalt ions, which was only discovered after their widespread implantation into patients requiring hip replacements. These cobalt ions can result in local toxic effects-including peri-implant toxicity, aseptic loosening, and pseudotumor-as well as systemic toxic effects-including neurological, cardiovascular, and endocrine disorders. Failing metal-on-metal (MoM) implants usually necessitate painful, risky, and costly revision surgeries. To treat metallosis arising from failing MoM implants, a synovial fluid-mimicking chelator was designed to remove these metal ions. Hyaluronic acid (HA), the major chemical component of synovial fluid, was functionalized with British anti-Lewisite (BAL) to create a chelator (BAL-HA). BAL-HA effectively binds cobalt and rescues in vitro cell vitality (up to 370% of cells exposed to IC50 levels of cobalt) and enhances the rate of clearance of cobalt in vivo (t1/2 from 48 h to 6 h). A metallosis model was also created to investigate our therapy. Results demonstrate that BAL-HA chelator system is biocompatible and capable of capturing significant amounts of cobalt ions from the hip joint within 30 min, with no risk of kidney failure. This chelation therapy has the potential to mitigate cobalt toxicity from failing MoM implants through noninvasive injections into the joint.

Efficacy of a Novel Electroconductive Matrix To Treat Muscle Atrophy and Fat Accumulation in Chronic Massive Rotator Cuff Tears of the Shoulder

The high retear rate after a successful repair of the rotator cuff (RC) is a major clinical challenge. Muscle atrophy and fat accumulation of RC muscles over time adversely affect the rate of retear. Since current surgical techniques do not improve muscle degenerative conditions, new treatments are being developed to reduce muscle atrophy and fat accumulation. In the previous study, we have shown the efficacy of aligned electroconductive nanofibrous fabricated by coating poly(3,4-ethylene dioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) nanoparticles onto aligned poly(ε-caprolactone) (PCL) electrospun nanofibers (PEDOT:PSS matrix) to reduce muscle atrophy in acute and subacute models of RC tears (RCTs). In this study, we further evaluated the efficacy of the PEDOT:PSS matrix to reduce muscle atrophy and fat accumulation in a rat model of chronic massive full-thickness RCTs (MRCTs). The matrices were transplanted on the myotendinous junction to the belly of the supraspinatus and infraspinatus muscles at 16 weeks after MRCTs. The biomechanics and histological assessments showed the potential of the PEDOT:PSS matrix to suppress the progression of muscle atrophy, fat accumulation, and fibrosis in both supraspinatus and infraspinatus muscles at 24 and 32 weeks after MRCTs. We also demonstrated that the PEDOT:PSS matrix implantation significantly improved the tendon morphology and tensile properties compared with current surgical techniques.

Injectable and biodegradable piezoelectric hydrogel for osteoarthritis treatment

Osteoarthritis affects millions of people worldwide but current treatments using analgesics or anti-inflammatory drugs only alleviate symptoms of this disease. Here, we present an injectable, biodegradable piezoelectric hydrogel, made of short electrospun poly-L-lactic acid nanofibers embedded inside a collagen matrix, which can be injected into the joints and self-produce localized electrical cues under ultrasound activation to drive cartilage healing. In vitro, data shows that the piezoelectric hydrogel with ultrasound can enhance cell migration and induce stem cells to secrete TGF-β1, which promotes chondrogenesis. In vivo, the rabbits with osteochondral critical-size defects receiving the ultrasound-activated piezoelectric hydrogel show increased subchondral bone formation, improved hyaline-cartilage structure, and good mechanical properties, close to healthy native cartilage. This piezoelectric hydrogel is not only useful for cartilage healing but also potentially applicable to other tissue regeneration, offering a significant impact on the field of regenerative tissue engineering.

Erratum to "BME 2.0: Engineering the Future of Medicine"

[This corrects the article DOI: 10.34133/bmef.0001.].

Corrosion of Metals During Use in Arthroplasty

Arthroplasty implants can undergo corrosion at the modular components, trunnion, and hinges, owing to implant material makeup, micromotion, and interaction with body fluid. In this review, various mechanisms of corrosion in arthroplasty were explored with suggestions on means of improvement. We identified 10 methods including pitting, crevice, mechanically assisted crevice corrosion, fretting, fretting initiated crevice corrosion, mechanically assisted taper corrosion, galvanic corrosion, stress/tension, fatigue corrosion, and inflammatory cell induced corrosion. The position of implants on the galvanic series, and their ability to maintain passivation contribute to their longevity in service. Due to the relative motion of arthroplastic components, bio-tribocorrosion may disrupt passive oxide films, and pitting is initiated at interfaces. Thus, corrosion in arthroplasty as an electrochemical phenomenon mainly starts on one spot and progresses in 3 steps: (1) the oxidative dissolution of metal from implant surfaces into the aqueous active environment, releasing cations, (2) the attraction of electrons to the opposite charge created at another point of the implant surface, producing current flow, and (3) the formation of oxides of metal and metal hydroxides deposited as rust at the surface of the implant. Recent innovations in material manufacturing continue to improve the efficiency of arthroplasty; however, the component parts remain susceptible to bio-tribocorrosion. Thus, a complete eradication of corrosion in arthroplasty would require futuristic materials with improvement in recent materials and designs, derived from knowledge of existing retrieved implants, and strategies to provide overall surface finishes that protect against bio-tribocorrosion.

Regenerative engineering of long bones using the small molecule forskolin

Bone grafting procedures have become increasingly common in the United States, with approximately 500,000 cases occurring each year at a societal cost exceeding $2.4 billion. Recombinant human bone morphogenetic proteins (rhBMPs) are therapeutic agents that have been widely used by orthopedic surgeons to stimulate bone tissue formation alone and when paired with biomaterials. However, significant limitations such as immunogenicity, high production cost, and ectopic bone growth from these therapies remain. Therefore, efforts have been made to discover and repurpose osteoinductive small-molecule therapeutics to promote bone regeneration. Previously, we have demonstrated that a single-dose treatment with the small-molecule forskolin for just 24 h induces osteogenic differentiation of rabbit bone marrow-derived stem cells in vitro, while mitigating adverse side effects attributed with prolonged small-molecule treatment schemes. In this study, we engineered a composite fibrin-PLGA [poly(lactide-co-glycolide)]-sintered microsphere scaffold for the localized, short-term delivery of the osteoinductive small molecule, forskolin. In vitro characterization studies showed that forskolin released out of the fibrin gel within the first 24 h and retained its bioactivity toward osteogenic differentiation of bone marrow-derived stem cells. The forskolin-loaded fibrin-PLGA scaffold was also able to guide bone formation in a 3-mo rabbit radial critical-sized defect model comparable to recombinant human bone morphogenetic protein-2 (rhBMP-2) treatment, as demonstrated through histological and mechanical evaluation, with minimal systemic off-target side effects. Together, these results demonstrate the successful application of an innovative small-molecule treatment approach within long bone critical-sized defects.

Oxygen-Generating Biomaterials for Translational Bone Regenerative Engineering

Successful regeneration of critical-size defects remains one of the significant challenges in regenerative engineering. These large-scale bone defects are difficult to regenerate and are often reconstructed with matrices that do not provide adequate oxygen levels to stem cells involved in the regeneration process. Hypoxia-induced necrosis predominantly occurs in the center of large matrices since the host tissue's local vasculature fails to provide sufficient nutrients and oxygen. Indeed, utilizing oxygen-generating materials can overcome the central hypoxic region, induce tissue in-growth, and increase the quality of life for patients with extensive tissue damage. This article reviews recent advances in oxygen-generating biomaterials for translational bone regenerative engineering. We discussed different oxygen-releasing and delivery methods, fabrication methods for oxygen-releasing matrices, biology, oxygen's role in bone regeneration, and emerging new oxygen delivery methods that could potentially be used for bone regenerative engineering.

BME 2.0: Engineering the Future of Medicine

If the 20th century was the age of mapping and controlling the external world, the 21st century is the biomedical age of mapping and controlling the biological internal world. The biomedical age is bringing new technological breakthroughs for sensing and controlling human biomolecules, cells, tissues, and organs, which underpin new frontiers in the biomedical discovery, data, biomanufacturing, and translational sciences. This article reviews what we believe will be the next wave of biomedical engineering (BME) education in support of the biomedical age, what we have termed BME 2.0. BME 2.0 was announced on October 12 2017 at BMES 49 (https://www.bme.jhu.edu/news-events/news/miller-opens-2017-bmes-annual-meeting-with-vision-for-new-bme-era/). We present several principles upon which we believe the BME 2.0 curriculum should be constructed, and from these principles, we describe what view as the foundations that form the next generations of curricula in support of the BME enterprise. The core principles of BME 2.0 education are (a) educate students bilingually, from day 1, in the languages of modern molecular biology and the analytical modeling of complex biological systems; (b) prepare every student to be a biomedical data scientist; (c) build a unique BME community for discovery and innovation via a vertically integrated and convergent learning environment spanning the university and hospital systems; (d) champion an educational culture of inclusive excellence; and (e) codify in the curriculum ongoing discoveries at the frontiers of the discipline, thus ensuring BME 2.0 as a launchpad for training the future leaders of the biotechnology marketplaces. We envision that the BME 2.0 education is the path for providing every student with the training to lead in this new era of engineering the future of medicine in the 21st century.

Osteochondral regenerative engineering: challenges, state-of-the-art and translational perspectives

Despite quantum leaps, the biomimetic regeneration of cartilage and osteochondral regeneration remains a major challenge, owing to the complex and hierarchical nature of compositional, structural and functional properties. In this review, an account of the prevailing challenges in biomimicking the gradients in porous microstructure, cells and extracellular matrix (ECM) orientation is presented. Further, the spatial arrangement of the cues in inducing vascularization in the subchondral bone region while maintaining the avascular nature of the adjacent cartilage layer is highlighted. With rapid advancement in biomaterials science, biofabrication tools and strategies, the state-of-the-art in osteochondral regeneration since the last decade has expansively elaborated. This includes conventional and additive manufacturing of synthetic/natural/ECM-based biomaterials, tissue-specific/mesenchymal/progenitor cells, growth factors and/or signaling biomolecules. Beyond the laboratory-based research and development, the underlying challenges in translational research are also provided in a dedicated section. A new generation of biomaterial-based acellular scaffold systems with uncompromised biocompatibility and osteochondral regenerative capability is necessary to bridge the clinical demand and commercial supply. Encompassing the basic elements of osteochondral research, this review is believed to serve as a standalone guide for early career researchers, in expanding the research horizon to improve the quality of life of osteoarthritic patients affordably.

Overexpression of NDST1 Attenuates Fibrotic Response in Murine Adipose-Derived Stem Cells

Adipose-derived stem cells (ADSCs) hold tremendous potential for treating diseases and repairing damaged tissues. Heparan sulfate (HS) plays various roles in cellular signaling mechanisms. The importance of HS in stem cell function has been reported and well documented. However, there has been little progress in using HS for therapeutic purposes. We focused on one of the sulfotransferases, NDST1, which influences overall HS chain extent and sulfation pattern, with the expectation to enhance stem cell function by increasing the N-sulfation level. We herein performed transfections of a green fluorescent protein-vector control and NDST1-vector into mouse ADSCs to evaluate stem cell functions. Overexpression of NDST1 suppressed the osteogenic differentiation of ADSCs. There was no pronounced effect observed on the stemness, inflammatory gene expression, nor any noticeable effect in adipogenic and chondrogenic differentiation. Under the tumor necrosis factor-alpha stimulation, NDST1 overexpression induced several chemokine productions that attract neutrophils and macrophages. Finally, we identified an antifibrotic response in ADSCs overexpressing NDST1. This study provides a foundation for the evaluation of HS-related effects in ADSCs undergoing ex vivo gene manipulation.

Ultra-low binder content 3D printed calcium phosphate graphene scaffolds as resorbable, osteoinductive matrices that support bone formation in vivo

Bone regenerative engineering could replace autografts; however, no synthetic material fulfills all design criteria. Nanocarbons incorporated into three-dimensional printed (3DP) matrices can improve properties, but incorporation is constrained to low wt%. Further, unmodified nanocarbons have limited osteogenic potential. Functionalization to calcium phosphate graphene (CaPG) imparts osteoinductivity and osteoconductivity, but loading into matrices remained limited. This work presents ultra-high content (90%), 3DP-CaPG matrices. 3DP-CaPG matrices are highly porous (95%), moderately stiff (3 MPa), and mechanically robust. In vitro, they are cytocompatible and induce osteogenic differentiation of human mesenchymal stem cells (hMSCs), indicated by alkaline phosphatase, mineralization, and COL1α1 expression. In vivo, bone regeneration was studied using a transgenic fluorescent-reporter mouse non-union calvarial defect model. 3DP-CaPG stimulates cellular ingrowth, retains donor cells, and induces osteogenic differentiation. Histology shows TRAP staining around struts, suggesting potential osteoclast activity. Apparent resorption of 3DP-CaPG was observed and presented no toxicity. 3DP-CaPG represents an advancement towards a synthetic bone regeneration matrix.

Biodegradable Polyphosphazenes for Regenerative Engineering

Regenerative engineering is a field that seeks to regenerate complex tissues and biological systems, rather than simply restore and repair individual tissues or organs. Since the first introduction of regenerative engineering in 2012, numerous research has been devoted to the development of this field. Biodegradable polymers such as polyphosphazenes in particular have drawn significant interest as regenerative engineering materials for their synthetic flexibility in designing into materials with a wide range of mechanical properties, degradation rates, and chemical functionality. These polyphosphazenes can go through complete hydrolytic degradation and provide harmlessly and pH neutral buffering degradation products such as phosphates and ammonia, which is crucial for reducing inflammation in vivo. Here, we discuss the current accomplishments of polyphosphazene, different methods for synthesizing them, and their applications in tissue regeneration such as bones, nerves, and elastic tissues.

Pegylated insulin-like growth factor-1 biotherapeutic delivery promotes rotator cuff regeneration in a rat model

Tears in the rotator cuff are challenging to repair because of the complex, hypocellular, hypovascular, and movement-active nature of the tendon and its enthesis. Insulin-like Growth Factor-1 (IGF-1) is a promising therapeutic for this repair. However, its unstable nature, short half-life, and ability to disrupt homeostasis has limited its clinical translation. Pegylation has been shown to improve the stability and sustain IGF-1 levels in the systemic circulation without disrupting homeostasis. To provide localized delivery of IGF-1 in the repaired tendons, we encapsulated pegylated IGF-1 mimic and its controls (unpegylated IGF-1 mimic and recombinant human IGF-1) in polycaprolactone-based matrices and evaluated them in a pre-clinical rodent model of rotator cuff repair. Pegylated-IGF-1 mimic delivery reestablished the characteristic tendon-to-bone enthesis structure and improved tendon tensile properties within 8 weeks of repair compared to controls, signifying the importance of pegylation in this complex tissue regeneration. These results demonstrate a simple and scalable biologic delivery technology alternative to tissue-derived grafts for soft tissue repair.

Injectable amnion hydrogel-mediated delivery of adipose-derived stem cells for osteoarthritis treatment

Current treatment strategies for osteoarthritis (OA) predominantly address symptoms with limited disease-modifying potential. There is a growing interest in the use of adipose-derived stem cells (ADSCs) for OA treatment and developing biomimetic injectable hydrogels as cell delivery systems. Biomimetic injectable hydrogels can simulate the native tissue microenvironment by providing appropriate biological and chemical cues for tissue regeneration. A biomimetic injectable hydrogel using amnion membrane (AM) was developed which can self-assemble in situ and retain the stem cells at the target site. In the present study, we evaluated the efficacy of intraarticular injections of AM hydrogels with and without ADSCs in reducing inflammation and cartilage degeneration in a collagenase-induced OA rat model. A week after the induction of OA, rats were treated with control (phosphate-buffered saline), ADSCs, AM gel, and AM-ADSCs. Inflammation and cartilage regeneration was evaluated by joint swelling, analysis of serum by cytokine profiling and Raman spectroscopy, gross appearance, and histology. Both AM and ADSC possess antiinflammatory and chondroprotective properties to target the sites of inflammation in an osteoarthritic joint, thereby reducing the inflammation-mediated damage to the articular cartilage. The present study demonstrated the potential of AM hydrogel to foster cartilage tissue regeneration, a comparable regenerative effect of AM hydrogel and ADSCs, and the synergistic antiinflammatory and chondroprotective effects of AM and ADSC to regenerate cartilage tissue in a rat OA model.

Exercise-induced piezoelectric stimulation for cartilage regeneration in rabbits

More than 32.5 million American adults suffer from osteoarthritis, and current treatments including pain medicines and anti-inflammatory drugs only alleviate symptoms but do not cure the disease. Here, we have demonstrated that a biodegradable piezoelectric poly(L-lactic acid) (PLLA) nanofiber scaffold under applied force or joint load could act as a battery-less electrical stimulator to promote chondrogenesis and cartilage regeneration. The PLLA scaffold under applied force or joint load generated a controllable piezoelectric charge, which promoted extracellular protein adsorption, facilitated cell migration or recruitment, induced endogenous TGF-β via calcium signaling pathway, and improved chondrogenesis and cartilage regeneration both in vitro and in vivo. Rabbits with critical-sized osteochondral defects receiving the piezoelectric scaffold and exercise treatment experienced hyaline-cartilage regeneration and completely healed cartilage with abundant chondrocytes and type II collagen after 1 to 2 months of exercise (2 to 3 months after surgery including 1 month of recovery before exercise), whereas rabbits treated with nonpiezoelectric scaffold and exercise treatment had unfilled defect and limited healing. The approach of combining biodegradable piezoelectric tissue scaffolds with controlled mechanical activation (via physical exercise) may therefore be useful for the treatment of osteoarthritis and is potentially applicable to regenerating other injured tissues.

The Role of Nanomaterials and Biological Agents on Rotator Cuff Regeneration

The rotator cuff is a musculotendon unit responsible for movement in the shoulder. Rotator cuff tears represent a significant number of musculoskeletal injuries in the adult population. In addition, there is a high incidence of retear rates due to various complications within the complex anatomical structure and the lack of proper healing. Current clinical strategies for rotator cuff augmentation include surgical intervention with autograft tissue grafts and beneficial impacts have been shown, but challenges still exist because of limited supply. For decades, nanomaterials have been engineered for the repair of various tissue and organ systems. This review article provides a thorough summary of the role nanomaterials, stem cells and biological agents have played in rotator cuff repair to date and offers input on next generation approaches for regenerating this tissue.

Ligament Regenerative Engineering: Braiding Scalable and Tunable Bioengineered Ligaments Using a Bench-Top Braiding Machine

Anterior cruciate ligament (ACL) injuries are common sports injuries that typically require surgical intervention. Autografts and allografts are used to replace damaged ligaments. The drawbacks of autografts and allografts, which include donor site morbidity and variability in quality, have spurred research in the development of bioengineered ligaments. Herein, the design and development of a cost-effective bench-top 3D braiding machine that fabricates scalable and tunable bioengineered ligaments is described. It was demonstrated that braiding angle and picks per inch can be controlled with the bench-top braiding machine. Pore sizes within the reported range needed for vascularization and bone regeneration are demonstrated. By considering a one-to-one linear relationship between cross-sectional area and peak load, the bench-top braiding machine can theoretically fabricate bioengineered ligaments with a peak load that is 9× greater than the human ACL. This bench-top braiding machine is generalizable to all types of yarns and may be used for regenerative engineering applications.

Kinetic degradation and biocompatibility evaluation of polycaprolactone-based biologics delivery matrices for regenerative engineering of the rotator cuff

Whereas synthetic biodegradable polymers have been successfully applied for the delivery of biologics in other tissues, the anatomical complexity, poor blood supply, and reduced clearance of degradation byproducts in the rotator cuff create unique design challenges for implantable biomaterials. Here, we investigated lower molecular weight poly-lactic acid co-epsilon-caprolactone (PLA-CL) formulations with varying molecular weight and film casting concentrations as potential matrices for the therapeutic delivery of biologics in the rotator cuff. Matrices were fabricated with target footprint dimensions to facilitate controlled and protected release of model biologic (Bovine Serum Albumin), and anatomically-unhindered implantation under the acromion in a rodent model of acute rotator cuff repair. The matrix obtained from the highest polymeric-film casting concentration showed a controlled release of model biologics payload. The tested matrices rapidly degraded during the initial 4 weeks due to preferential hydrolysis of the lactide-rich regions within the polymer, and subsequently maintained a stable molecular weight due to the emergence of highly-crystalline caprolactone-rich regions. pH evaluation in the interior of the matrix showed minimal change signifying lesser accumulation of acidic degradation byproducts than seen in other bulk-degrading polymers, and maintenance of conformational stability of the model biologic payload. The context-dependent biocompatibility evaluation in a rodent model of acute rotator cuff repair showed matrix remodeling without eliciting excessive inflammatory reaction and is anticipated to completely degrade within 6 months. The engineered PLA-CL matrices offer unique advantages in controlled and protected biologic delivery, non-toxic biodegradation, and biocompatibility overcoming several limitations of commonly-used biodegradable polyesters.

Changes in COVID-19-Associated Deaths During a Year Among Blacks and Hispanics Compared to Whites in the State of Connecticut

Background

With recent COVID-19 vaccination rates relatively high in the USA, the USA still maintains the most documented cases globally,[1] even though COVID-19 cases, hospitalization, and mortality have been declining. However, the health burden has been largely felt in communities involving racial and ethnic minorities. Thus, in order to provide a clearer picture of what is happening in Black, Indigenous, and people of color communities, we examined the racial/ethnic differences of monthly COVID-19 deaths in Connecticut.

Methods

This is an epidemiological study analyzing mortality data from March 1, 2020, to February 28, 2021, obtained from the Connecticut State Department of Public Health. The data include cause of death (COVID-19 death identified by ICD-10 code U071), race/ethnicity (non-Hispanic White (White), non-Hispanic Black (Black), and Hispanic), sex, and age. Both crude and age-adjusted rates were reported by racial/ethnic groups. To compare age-adjusted rates between racial groups, with estimated age-adjusted death counts as outcomes, between-racial group rate ratios, 95% confidence intervals, and p values significant at < 0.05 were derived from the Poisson regression model.

Results

From March 2020 to May 2020 (wave 1) of COVID-19 cases, the COVID-19-related mortality rates were the highest for all three race groups (Whites, Blacks, and Hispanics) with statistical group differences (p < 0.05). Blacks had the highest rates of deaths followed by Hispanics and then Whites. Further, more Whites died in a nursing home when compared to Blacks and Hispanics. From June 2010 to October 2020 (wave 2), COVID-19 mortality declined significantly for all three race groups with no statistical differences between groups. COVID-19 deaths in nursing homes declined for all three racial/ethnic groups. From November 2020 to February 2021 (wave 3), COVID-19 mortality rates were significantly higher compared to wave 2 but lower than wave 1 for all three race groups. The mortality rates for Blacks and Hispanics were higher than Whites. Hispanics had the highest rates of deaths, followed by Blacks, and then Whites (p < 0.05). Whites showed the lowest mortality rates among all three racial/ethnic groups.

Conclusions

In summary, COVID-19 health disparities among Black and Hispanic populations were evident in this study. Blacks and Hispanics had significantly higher mortality rates when compared to Whites. Blacks had the highest mortality rates during wave 1, and in wave 3, Hispanics has the highest mortality rates. Our data are important because they show monthly COVID-19 deaths data by race. Data reported this way gives a better and more accurate understanding of what is really happening in Black, Indigenous, and people of color populations.

Inductive Materials for Regenerative Engineering

Regenerative engineering has pioneered several novel biomaterials to treat critical-sized bone injuries. However, despite significant improvement in synthetic materials research, some limitations still exist. The constraints correlated with the current grafting methods signify a treatment paradigm shift to osteoinductive regenerative engineering approaches. Because of their intrinsic potential, inductive biomaterials may represent alternative approaches to treating critical bone injuries. Osteoinductive scaffolds stimulate stem cell differentiation into the osteoblastic lineage, enhancing bone regeneration. Inductive biomaterials comprise polymers, calcium phosphate ceramics, metals, and graphene family materials. This review will assess the cellular behavior toward properties of inductive materials.

Stromal Vascular Fraction for Osteoarthritis of the Knee Regenerative Engineering

Purpose

The knee joint is prone to osteoarthritis (OA) due to its anatomical position, and several reports have implicated the imbalance between catabolic and anabolic processes within the joint as the main culprit, thus leading to investigations towards attenuation of these inflammatory signals for OA treatment. In this review, we have explored clinical evidence supporting the use of stromal vascular fraction (SVF), known for its anti-inflammatory characteristics for the treatment of OA.

Methods

Searches were made on PubMed, PMC, and Google Scholar with the keywords “adipose fraction knee regeneration, and stromal vascular fraction knee regeneration, and limiting searches within 2017–2020.

Results

Frequently found interventions include cultured adipose-derived stem cells (ADSCs), SVF, and the micronized/microfragmented adipose tissue-stromal vascular fraction (MAT-SVF). Clinical data reported that joints treated with SVF provided a better quality of life to patients. Currently, MAT-SVF obtained and administered at the point of care is approved by the Food and Drug Administration (FDA), but more studies including manufacturing validation, safety, and proof of pharmacological activity are needed for SVF. The mechanism of action of MAT-SVF is also not fully understood. However, the current hypothesis indicates a direct adherence and integration with the degenerative host tissue, and/or trophic effects resulting from the secretome of constituent cells.

Conclusion

Our review of the literature on stromal vascular fraction and related therapy use has found evidence of efficacy in results. More research and clinical patient follow-up are needed to determine the proper place of these therapies in the treatment of osteoarthritis of the knee.

Lay Summary

Reports have implicated the increased inflammatory proteins within the joints as the main cause of osteoarthritis (OA). This has attracted interest towards addressing these inflammatory proteins as a way of treatment for OA. The concentrated cell-packed portion of the adipose product stromal vascular fraction (SVF) from liposuction or other methods possesses anti-inflammatory effects and has been acclaimed to heal OA. Thus, we searched for clinical evidence supporting their use, for OA treatment through examining the literature. Data from various hospitals support that joints treated with SVF provided a better quality of life to patients. Currently, there is at least one version of these products that are obtained and given back to patients during a single clinic visit, approved by the FDA.

Regenerative Engineering Animal Models for Knee Osteoarthritis

Abstract

Osteoarthritis (OA) of the knee is the most common synovial joint disorder worldwide, with a growing incidence due to increasing rates of obesity and an aging population. A significant amount of research is currently being conducted to further our understanding of the pathophysiology of knee osteoarthritis to design less invasive and more effective treatment options once conservative management has failed. Regenerative engineering techniques have shown promising preclinical results in treating OA due to their innovative approaches and have emerged as a popular area of study. To investigate these therapeutics, animal models of OA have been used in preclinical trials. There are various mechanisms by which OA can be induced in the knee/stifle of animals that are classified by the etiology of the OA that they are designed to recapitulate. Thus, it is essential to utilize the correct animal model in studies that are investigating regenerative engineering techniques for proper translation of efficacy into clinical trials. This review discusses the various animal models of OA that may be used in preclinical regenerative engineering trials and the corresponding classification system.

Lay Summary

Osteoarthritis (OA) of the knee is the most common synovial joint disease worldwide, with high rates of occurrence due to an increase in obesity and an aging population. A great deal of research is currently underway to further our understanding of the causes of osteoarthritis, to design more effective treatments. The emergence of regenerative engineering has provided physicians and investigators with unique opportunities to join ideas in tackling human diseases such as OA. Once the concept is proven to work, the initial procedure for the evaluation of a treatment solution begins with an animal model. Thus, it is essential to utilize a suitable animal model that reflects the particular ailment in regenerative engineering studies for proper translation to human patients as each model has associated advantages and disadvantages. There are various ways by which OA can occur in the knee joint, which are classified according to the particular cause of the OA. This review discusses the various animal models of OA that may be used in preclinical regenerative engineering investigations and the corresponding classification system.

The COVID-19 Vaccine and the Black Community: Addressing the Justified Questions

Established in 2019, the Roundtable on Black Men and Black Women in STEM convenes a broad array of stakeholders that focus on the barriers and opportunities encountered by Black men and Black women as they navigate the pathways from K-12 and postsecondary education to careers in science, engineering, and medicine. Through meetings, public workshops, and publications, the Roundtable advances discussions that raise awareness and/or highlight promising practices for increasing the representation, retention, and inclusiveness of Black men and Black women in STEM. In keeping with the charge of the Roundtable, Roundtable leadership and leaders of the COVID-19 action group conducted an informational video in January 2021 to provide an in-depth discussion around common, justified questions in the Black community pertaining to the COVID-19 vaccine. The manuscript addresses selected questions and answers relating to the different types of COVID-19 vaccines and their development, administration, and effectiveness. Discussion focuses on addressing vaccine misconceptions, misinformation, mistrust, and hesitancy; challenges in prioritizing vaccinations in diverse populations and communities; dealing with racism in medicine and public health; optimizing communication and health education; and offering practical strategies and recommendations for improving vaccine acceptance by clinicians, health care workers, and the Black community. This manuscript summarizes the content in the YouTube video ( https://www.youtube.com/watch?v=wdEC9c48A_k ).

Fentanyl, Heroin, and Cocaine Overdose Fatalities are Shifting to the Black Community: An Analysis of the State of Connecticut

BACKGROUND

Historically, Blacks and Hispanics have had lower opioid-involved overdose death rates in Connecticut (CT). We examined if a shift has taken place where rates of Black fatal overdoses have now surpassed Whites in the state.

METHODS

Drug overdose fatality rates were calculated by number of deaths per year per 100,000 population from 2012 to 2019 in Connecticut. Measures were by race (White, Hispanic, Black, and Asian or Pacific Islander), age groups, and types of drugs, including fentanyl, heroin, cocaine, and other opioids. Poisson regression was used to test the interactions (race × age); joinpoint regression analysis was used to evaluate trend lines of fatality rate by racial/ethnic group within each age group with a significance level of p < 0.05.

RESULTS

Drug overdose fatality rates in CT from 2012 to 2019 showed a significant increase for all races combined, estimated 3.6 deaths per 100,000 population per year. For Whites, overdose deaths were 4.6 per year from 2012 to 2017 with no change from 2017 to 2019. The overdose fatality rate for Hispanics was 3.0 and for Asian or Pacific Islanders 0.6 per year from 2012 to 2019. For Blacks, the death rates were statistically flat between 2012 and 2014; however, from 2015 to 2019, this group saw the largest average increase of 6.0 overdose deaths per 100,000 population each year. By 2019, the overdose fatality rate was higher in Blacks than in Whites, (39 vs. 38 per 100,000, respectively). Further, Blacks ages 50 years and over reported the highest overdose fatality rates among all race/age groups, an increase of 8.5 deaths per 100,000 population since 2014.

CONCLUSIONS AND RELEVANCE

Connecticut is a microcosm of the opioid overdose trend in the New England region of our country. The majority of overdose deaths in CT involved illicit drugs, fentanyl, heroin, and cocaine, rather than prescription drugs. Blacks 50-years-old and over showed the fastest growing overdose death rates. Opioid deaths are now shifting to the Black community, creating an urgent public health crisis.

Regenerative engineering: a review of recent advances and future directions

Regenerative engineering is defined as the convergence of the disciplines of advanced material science, stem cell science, physics, developmental biology and clinical translation for the regeneration of complex tissues and organ systems. It is an expansion of tissue engineering, which was first developed as a method of repair and restoration of human tissue. In the past three decades, advances in regenerative engineering have made it possible to treat a variety of clinical challenges by utilizing cutting-edge technology currently available to harness the body's healing and regenerative abilities. The emergence of new information in developmental biology, stem cell science, advanced material science and nanotechnology have provided promising concepts and approaches to regenerate complex tissues and structures.

In Vivo Evaluation of the Regenerative Capability of Glycylglycine Ethyl Ester-Substituted Polyphosphazene and Poly(lactic-co-glycolic acid) Blends: A Rabbit Critical-Sized Bone Defect Model

In an effort to understand the biological capability of polyphosphazene-based polymers, three-dimensional biomimetic bone scaffolds were fabricated using the blends of poly[(glycine ethylglycinato)₇₅(phenylphenoxy)₂₅]phosphazene (PNGEGPhPh) and poly(lactic-co-glycolic acid) (PLGA), and an in vivo evaluation was performed in a rabbit critical-sized bone defect model. The matrices constructed from PNGEGPhPh-PLGA blends were surgically implanted into 15 mm critical-sized radial defects of the rabbits as structural templates for bone tissue regeneration. PLGA, which is the most commonly used synthetic bone graft substitute, was used as a control in this study. Radiological and histological analyses demonstrated that PNGEGPhPh-PLGA blends exhibited favorable in vivo biocompatibility and osteoconductivity, as the newly designed matrices allowed new bone formation to occur without adverse immunoreactions. The X-ray images of the blends showed higher levels of radiodensity than that of the pristine PLGA, indicating higher rates of new bone formation and regeneration. Micro-computed tomography quantification revealed that new bone volume fractions were significantly higher for the PNGEGPhPh-PLGA blends than for the PLGA controls after 4 weeks. The new bone volume increased linearly with increasing time points, with the new tissues observed throughout the defect area for the blend and only at the implant site's extremes for the PLGA control. Histologically, the polyphosphazene system appeared to show tissue responses and bone ingrowths superior to PLGA. By the end of the study, the defects with PNGEGPhPh-PLGA scaffolds exhibited evidence of effective bone tissue ingrowth and minimal inflammatory responses. Thus, polyphosphazene-containing biomaterials have excellent translational potential for use in bone regenerative engineering applications.

Addressing Justified Vaccine Hesitancy in the Black Community

The Coronavirus disease 2019 (COVID-19) pandemic has had a terrible and long-lasting impact on the world. As the infection spreads, the projected mortality and economic devastation are unprecedented. Racism and its subsequent effects on social and economic factors have resulted in the virus disproportionally effecting Black people. Given that the virus has hit the Black community the hardest, I am concerned now that vaccine hesitancy may perpetuate the health disparities that we are currently seeing in the numbers of infections and deaths taking place in the Black community.

Excess Deaths Among Blacks and Latinx Compared to Whites During Covid-19

Importance

Blacks and Latinx are disproportionately affected by Coronavirus disease 2019 (Covid-19) and experience higher mortality rates than Whites and Asians in the USA. Such racial disparities, in Covid-19 testing, cases, and mortality are visible in Connecticut too. Recently, excess deaths have become an important consideration in news reports and academic research. However, data on racial differences in excess death is limited.

Objective

This study examines racial/ethnic differences in excess deaths in the state of Connecticut during the Covid-19 pandemic.

Design

This is a cross-sectional epidemiological study to estimate excess deaths by racial/ethnic status utilizing mortality data during the peak months of Covid-19 infections from March 1 to June 30, 2020, in Connecticut. The following assumption is applied: expected non-Covid-19 deaths from March 1 to June 30, 2020, are equal to the number of deaths occurring during the period of March 1 to June 30, 2019. Race/ethnicity are defined as Non-Hispanic White, Non-Hispanic Black, and Latinx. Descriptive statistics and rates with 95% confidence intervals are presented. Chi-square analyses are performed where applicable.

Setting

Connecticut

Participants

All deaths in Connecticut from March 1 to June 30, 2020.

Exposure

Covid-19 and race/ethnicity

Results

From March 1 to June 30, 2020, a total of 14,226 all-cause deaths occurred including 1514 Blacks (10.6%), 1095 Latinx (7.7%), and 11,617 Whites (81.7%). This represented a 74% increase in mortality for Blacks; 63% for Latinx, and 30% for Whites. In addition, 42.70% of the deaths in Blacks were attributed to Covid-19; 38.5% for Latinx, and 23.0% for Whites (p<0.001). Covid-19 deaths accounted for over 90% of the excess deaths in Blacks and Hispanics. In contrast, in Whites, Covid-19 deaths exceeded the number of excess deaths by 353 cases (113.2%), indicating that some Whites may have died from other underlined health conditions with a positive Covid-19 diagnosis. Furthermore, there was an increase in undetermined deaths in 2020, which accounted for 10.8% of deaths in Blacks, 13% in Latinx, and 6.2% of deaths in Whites.

Conclusions and Relevance

Excess deaths in Blacks and Latinx were found above the numbers of deaths determined to have occurred due to Covid-19. The fact that a large number of undetermined deaths were found for Blacks and Latinx individuals, and testing rates for Blacks and Latinx individuals (as determined by positivity rates) were lacking during this period strongly suggests, these excess deaths were Covid-19-related deaths.

The study findings indicate that Black and Latinx COVID-19-related deaths may be underreported in this pandemic. We advocate for targeted strategies that increase testing capacity, treatment, and vaccine availability in Black and Latinx communities.

The Treatment of Muscle Atrophy after Rotator Cuff Tears Using Electroconductive Nanofibrous Matrices

Rotator cuff tears (RCTs) are a common cause of disability and pain in the adult population. Despite the successful repair of the torn tendon, the delay between the time of injury and time of repair can cause muscle atrophy. The goal of the study was to engineer an electroconductive nanofibrous matrix with an aligned orientation to enhance muscle regeneration after rotator cuff (RC) repair. The electroconductive nanofibrous matrix was fabricated by coating Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) nanoparticles onto the aligned poly(ε-caprolactone) (PCL) electrospun nanofibers. The regenerative potential of the matrix was evaluated using two repair models of RCTs include acute and sub-acute. Sprague-Dawley rats (n=39) were randomly assigned to 1 of 8 groups. For the acute model, the matrix was implanted on supraspinatus muscle immediately after the injury. The repair surgery for the sub-acute model was conducted 6 weeks after injury. The supraspinatus muscle was harvested for histological analysis two and six weeks after repair. The results demonstrated the efficacy of electrical and topographical cues on the treatment of muscle atrophy in vivo. In both acute and sub-acute models, the stimulus effects of topographical and electrical cues reduced the gap area between muscle fibers. This study showed that muscle atrophy can be alleviated by successful surgical repair using an electroconductive nanofibrous matrix in a rat RC model.

Control of mesenchymal cell fate via application of FGF-8b in vitro

In order to develop strategies to regenerate complex tissues in mammals, understanding the role of signaling in regeneration competent species and mammalian development is of critical importance. Fibroblast growth factor 8 (FGF-8) signaling has an essential role in limb morphogenesis and blastema outgrowth. Therefore, we aimed to study the effect of FGF-8b on the proliferation and differentiation of mesenchymal stem cells (MSCs), which have tremendous potential for therapeutic use of cell-based therapy. Rat adipose derived stem cells (ADSCs) and muscle progenitor cells (MPCs) were isolated and cultured in growth medium and various types of differentiation medium (osteogenic, chondrogenic, adipogenic, tenogenic, and myogenic medium) with or without FGF-8b supplementation. We found that FGF-8b induced robust proliferation regardless of culture medium. Genes related to limb development were upregulated in ADSCs by FGF-8b supplementation. Moreover, FGF-8b enhanced chondrogenic differentiation and suppressed adipogenic and tenogenic differentiation in ADSCs. Osteogenic differentiation was not affected by FGF-8b supplementation. FGF-8b was found to enhance myofiber formation in rat MPCs. Overall, this study provides foundational knowledge on the effect of FGF-8b in the proliferation and fate determination of MSCs and provides insight in its potential efficacy for musculoskeletal therapies.

Enhancing the Surface Properties of a Bioengineered Anterior Cruciate Ligament Matrix for Use with Point-of-Care Stem Cell Therapy

We have previously developed a poly(L-lactic) acid (PLLA) bioengineered anterior cruciate ligament (ACL) matrix that has demonstrated enhanced healing when seeded with primary ACL cells prior to implantation in a rabbit model, as compared with the matrix alone. This suggests that improving cell adhesion on the matrix may beneficially affect the healing response and long-term performance of the bioengineered ACL matrix. One regenerative engineering approach involves enhancing the surface properties of the matrix to support cell adhesion and growth in combination with point-of-care stem cell therapy. Herein, we studied the cell adhesion properties of PLLA braided microfiber matrices enhanced through the physical adsorption of fibronectin and air plasma treatment. We evaluated the kinetics and binding efficiency of fibronectin onto matrices at three time points and three fibronectin concentrations. Incubating the matrix for 120 min in a solution of 25 mg mL^-1 fibronectin achieved the greatest binding efficiency to the matrix and cellular adhesion. Exposing the matrices to air plasma treatment for 5 min before fibronectin adsorption significantly enhanced the cell adhesion of rabbit bone marrow-derived mesenchymal stem cells (R-BMMSCs) 24 h post cell seeding. Finally, cellular proliferation was monitored for up to 21 d, the matrices were exposed to air plasma treatment, and fibronectin adsorption was found to result in enhanced cell number. These findings suggest that exposure to air plasma treatment and fibronectin adsorption enhances the cellular adhesion of PLLA braided microfiber matrices and may improve the clinical efficacy of the matrix in combination with point-of-care stem cell therapies.

Graphene-Based Biomaterials for Bone Regenerative Engineering: A Comprehensive Review of the Field and Considerations Regarding Biocompatibility and Biodegradation

Graphene and its derivatives have continued to garner worldwide interest due to their unique characteristics. Having expanded into biomedical applications, there have been efforts to employ their exceptional properties for the regeneration of different tissues, particularly bone. This article presents a comprehensive review on the usage of graphene-based materials for bone regenerative engineering. The graphene family of materials (GFMs) are used either alone or in combination with other biomaterials in the form of fillers in composites, coatings for both scaffolds and implants, or vehicles for the delivery of various signaling and therapeutic agents. The applications of the GFMs in each of these diverse areas are discussed and emphasis is placed on the characteristics of the GFMs that have implications in this regard. In tandem and of importance, this article evaluates the safety and biocompatibility of the GFMs and carefully elucidates how various factors influence the biocompatibility and biodegradability of this new class of nanomaterials. In conclusion, the challenges and opportunities regarding the use of the GFMs in regenerative engineering applications are discussed, and future perspectives for the developments in this field are proposed.

Fabrication and characterization of mechanically competent 3D printed polycaprolactone-reduced graphene oxide scaffolds

The ability to produce constructs with a high control over the bulk geometry and internal architecture has situated 3D printing as an attractive fabrication technique for scaffolds. Various designs and inks are actively investigated to prepare scaffolds for different tissues. In this work, we prepared 3D printed composite scaffolds comprising polycaprolactone (PCL) and various amounts of reduced graphene oxide (rGO) at 0.5, 1, and 3 wt.%. We employed a two-step fabrication process to ensure an even mixture and distribution of the rGO sheets within the PCL matrix. The inks were prepared by creating composite PCL-rGO films through solvent evaporation casting that were subsequently fed into the 3D printer for extrusion. The resultant scaffolds were seamlessly integrated, and 3D printed with high fidelity and consistency across all groups. This, together with the homogeneous dispersion of the rGO sheets within the polymer matrix, significantly improved the compressive strength and stiffness by 185% and 150%, respectively, at 0.5 wt.% rGO inclusion. The in vitro response of the scaffolds was assessed using human adipose-derived stem cells. All scaffolds were cytocompatible and supported cell growth and viability. These mechanically reinforced and biologically compatible 3D printed PCL-rGO scaffolds are a promising platform for regenerative engineering applications.

Biomedical applications of polyphosphazenes

Ever since the pioneering research efforts on their utility in biomedicine, polyphosphazene polymers have witnessed enormous growth and expansion in several biomedical applications due to their unique properties. The development of this exceptional biodegradable system with extraordinary design flexibility, property tunability and neutral bioactivity could stimulate an unprecedented paradigm in biomaterial design. Thus, polyphosphazenes are, undoubtedly, the next-generation biomaterials. This editorial provides a brief perspective on the promising prospects of polyphosphazene-based biomaterials for medical device technology, focusing mainly on the authors' work on this particular polymeric system.

Emergence of the Stem Cell Secretome in Regenerative Engineering

The secretome is defined as the set of molecules and biological factors that are secreted by cells into the extracellular space. In the past decade, secretome-based therapies have emerged as a promising approach to overcome the limitations associated with cell-based therapies for tissue and organ regeneration. Considering the growing number of recent publications related to secretome-based therapies, this review takes a step-by-step engineering approach to evaluate the role of the stem cell secretome in regenerative engineering. We discuss the functional benefits of the secretome, the techniques used to engineer the secretome and tailor its therapeutic effects, and the delivery systems and strategies that have been developed to use the secretome for tissue regeneration.