Helna Mary Baby's research while affiliated with Brigham and Women's Hospital and other places

An imperative requisite of tissue-engineered scaffolds is to promote host cell regeneration and concomitantly thwart microbial growth. Antibacterial agents are often added to prevent implant-related infections, which, however, aggravates the risk of bacterial resistance. For the first time, we report a fiber-based platform that selectively promotes the growth of mammalian cells and alleviates bacteria by varying fiber size, orientation, and material of polymeric yarns. The interactions of Gram-positive and -negative bacterial species with mammalian mesenchymal stem cells (MSC) were investigated on poly-€-caprolactone (PCL) yarns, polyethylene terephthalate (PET), poly-L-lactic acid (PLLA), and cotton. Various yarn configurations were studied by altering the fiber diameter (from nano- to microscale) and fiber orientations (aligned, twisted, and random) of PCL yarns. PCL nanofibrous yarn decreased the adhesion of S. aureus and E. coli, with a 2.7-fold and 1.5-fold reduction, respectively, compared to PCL microfibrous yarn. Among different fiber orientations, nanoaligned fibers resulted in an 8-fold and 30-fold reduction of S. aureus and E. coli adhesion compared to random fibers. Moreover, aligned orientation was superior in retarding the S. aureus adhesion by 14-fold compared to nanotwisted fibers. Our data demonstrate that polymeric yarns comprising fibers with nanoscale features and aligned orientation promote mammalian cell adhesion and spreading and concomitantly mitigate bacterial interaction. Moreover, we unveil the wicking of cells through polymeric yarns, facilitating early cell adhesion in fibrous scaffolds. Overall, this study provides insight to engineer scaffolds that couple superior interaction of mammalian cells with high-strength fibrous yarns for regenerative applications devoid of antibacterial agents or other surface modification strategies.

Respiratory infections pose a global health crisis. Vaccines are pathogen specific, and new vaccines are needed for mutants and emerging pathogens. Here, we report a drug free prophylactic platform - a Pathogen Capture and Neutralizing Spray (PCANS) that acts via a multi-pronged approach to prevent a broad spectrum of respiratory infections. PCANS forms a protective coating in the nasal cavity that enhances the capture of large respiratory droplets. The coating acts as a physical barrier against a broad spectrum of viruses and bacteria, and rapidly neutralizes them, reducing the pathogen load by >99.99%. In mice, PCANS showed nasal retention for at least 8 h and was safe for daily administration. A single prophylactic dose of PCANS protected mice against supra-lethal dosages of a mouse-adapted H1N1 Influenza virus (PR8), reduced lung viral titer by >99.99%, improved survival, and suppressed pathological manifestations. Together, our data suggest PCANS as a promising daily-use prophylactic approach against current and emerging respiratory infections.

Respiratory pathogens transmit primarily through particles such as droplets and aerosols. Although often overlooked, the resuspension of settled droplets is also a key facilitator of disease transmission. In this review, we discuss the three main mechanisms of aerosol generation: direct generation such as coughing and sneezing, indirect generation such as medical procedures, and resuspension of settled droplets and aerosols. The size of particles and environmental factors influence their airborne lifetime and ability to cause infection. Specifically, humidity and temperature are key factors controlling the evaporation of suspended droplets, consequently affecting the duration in which particles remain airborne. We also suggest material‐based approaches for effective prevention of disease transmission. These approaches include electrostatically charged virucidal agents and surface coatings, which have been shown to be highly effective in deactivating and reducing resuspension of pathogen‐laden aerosols. Virus dissemination through droplets or aerosols is a predominant transmission mode of respiratory infections. This review summarizes direct and indirect mechanisms of aerosol generation with an emphasis on infection risks presented by the resuspension of settled droplets. Material‐based approaches, including nanotechnology, to contain bioaerosol‐mediated virus transmission are highlighted in this review.

Globally, millions of patients are affected by myocardial infarction or lower limb gangrene/amputation due to atherosclerosis. Available surgical treatment based on vein and synthetic grafts provides sub-optimal benefits. We engineered a highly flexible and mechanically robust nanotextile-based vascular graft (NanoGraft) by interweaving nanofibrous threads of poly-L-lactic acid to address the unmet need. The NanoGrafts were rendered impervious with selective fibrin deposition in the micropores by pre-clotting. The pre-clotted NanoGrafts (4 mm diameter) and ePTFE were implanted in a porcine carotid artery replacement model. The fibrin-laden porous milieu facilitated rapid endothelization by the transmural angiogenesis in the NanoGraft. In-vivo patency of NanoGrafts was 100% at 2- and 4-weeks, with no changes over time in lumen size, flow velocities, and minimal foreign-body inflammatory reaction. However, the patency of ePTFE at 2-week was 66% and showed marked infiltration, neointimal thickening, and poor host tissue integration. The study demonstrates the in-vivo feasibility and safety of a thin-layered vascular prosthesis, viz., NanoGraft, and its potential superiority over the commercial ePTFE. Graphical Abstract