Effects of Different Radiation Sources on the Performance of Collagen-Based Corneal Repair Materials and Macrophage Polarization.

Owing to the lack of donor corneas, there is an urgent need for suitable corneal substitutes. As the main component of the corneal stroma, collagen has great advantages as a corneal repair material. If there are microorganisms such as bacteria in the corneal repair material, it may induce postoperative infection, causing the failure of corneal transplantation. Therefore, irradiation, as a common sterilization method, is often used to control the microorganisms in the material. However, it has not been reported which type of radiation source and what doses can sterilize more effectively without affecting the properties of collagen-based corneal repair materials (CCRMs) and have a positive impact on macrophage polarization. In this study, three different radiation sources of ultraviolet, cobalt-60, and electron beam at four different doses of 2, 5, 8, and 10 kGy were used to irradiate CCRMs. The swelling, stretching, transmittance, and degradation of the irradiated CCRMs were characterized, and the proliferation of human corneal epithelial cells on the irradiated CCRMs was characterized using the CCK8 kit. The results showed that low dose (<5 kGy) of radiation had little effect on the performance of CCRMs. Three irradiation methods with less influence were selected for the further study on RAW264.7 macrophage polarization. The results indicated that CCRMs treated with UV could downregulate the expression of pro-inflammatory related genes and upregulate the expression of anti-inflammatory genes in macrophages, which indicated that UV irradiation is a beneficial process for the preparation of CCRMs.

Assessing the aneurysm occlusion efficacy of a shear-thinning biomaterial in a 3D-printed model.

Metallic coil embolization is a common method for the endovascular treatment of visceral artery aneurysms (VAA) and visceral artery pseudoaneurysms (VAPA); however, this treatment is suboptimal due to the high cost of coils, incomplete volume occlusion, poor reendothelialization, aneurysm puncture, and coil migration. Several alternative treatment strategies are available, including stent flow diverters, glue embolics, gelfoam slurries, and vascular mesh plugs-each of which have their own disadvantages. Here, we investigated the in vitro capability of a shear-thinning biomaterial (STB), a nanocomposite hydrogel composed of gelatin and silicate nanoplatelets, for the minimally-invasive occlusion of simple necked aneurysm models. We demonstrated the injectability of STB through various clinical catheters, engineered an in vitro testing apparatus to independently manipulate aneurysm neck diameter, fluid flow rate, and flow waveform, and tested the stability of STB within the models under various conditions. Our experiments show that STB is able to withstand at least 1.89 Pa of wall shear stress, as estimated by computational fluid dynamics. STB is also able to withstand up to 10 mL s-1 pulsatile flow with a waveform mimicking blood flow in the human femoral artery and tolerate greater pressure changes than those in the human aorta. We ultimately found that our in vitro system was limited by supraphysiologic pressure changes caused by aneurysm models with low compliance.

Suspendable Hydrogel Nanovials for Massively Parallel Single-Cell Functional Analysis and Sorting.

Techniques to analyze and sort single cells based on functional outputs, such as secreted products, have the potential to transform our understanding of cellular biology as well as accelerate the development of next-generation cell and antibody therapies. However, secreted molecules rapidly diffuse away from cells, and analysis of these products requires specialized equipment and expertise to compartmentalize individual cells and capture their secretions. Herein, we describe methods to fabricate hydrogel-based chemically functionalized microcontainers, which we call nanovials, and demonstrate their use for sorting single viable cells based on their secreted products at high-throughput using only commonly accessible laboratory infrastructure. These nanovials act as solid supports that facilitate attachment of a variety of adherent and suspension cell types, partition uniform aqueous compartments, and capture secreted proteins. Solutions can be exchanged around nanovials to perform fluorescence immunoassays on secreted proteins. Using this platform and commercial flow sorters, we demonstrate high-throughput screening of stably and transiently transfected producer cells based on relative IgG production. Chinese hamster ovary cells sorted based on IgG production regrew and maintained a high secretion phenotype over at least a week, yielding >40% increase in bulk IgG production rates. We also sorted hybridomas and B lymphocytes based on antigen-specific antibody production. Hybridoma cells secreting an antihen egg lysozyme antibody were recovered from background cells, enriching a population of ∼4% prevalence to >90% following sorting. Leveraging the high-speed sorting capabilities of standard sorters, we sorted >1 million events in <1 h. IgG secreting mouse B cells were also sorted and enriched based on antigen-specific binding. Successful sorting of antibody-secreting B cells combined with the ability to perform single-cell RT-PCR to recover sequence information suggests the potential to perform antibody discovery workflows. The reported nanovials can be easily stored and distributed among researchers, democratizing access to high-throughput functional cell screening.

Synthesis of Injectable Shear-Thinning Biomaterials of Various Compositions of Gelatin and Synthetic Silicate Nanoplatelet.

Injectable shear-thinning biomaterials (iSTBs) have great potential for in situ tissue regeneration through minimally invasive therapeutics. Previously, an iSTB was developed by combining gelatin with synthetic silicate nanoplatelets (SNPs) for potential application to hemostasis and endovascular embolization. Hence, iSTBs are synthesized by varying compositions of gelatin and SNPs to navigate their material, mechanical, rheological, and bioactive properties. All compositions (each component percentage; 1.5-4.5%/total solid ranges; 3-9%) tested are injectable through both 5 Fr general catheter and 2.4 Fr microcatheter by manual pressure. In the results, an increase in gelatin contents causes decrease in swellability, increase in freeze-dried hydrogel scaffold porosity, increase in degradability and injection force during iSTB fabrication. Meanwhile, the amount of SNPs in composite hydrogels is mainly required to decrease degradability and increase shear thinning properties of iSTB. Finally, in vitro and in vivo biocompatibility tests show that the 1.5-4.5% range gelatin-SNP iSTBs are not toxic to the cells and animals. All results demonstrate that the iSTB can be modulated with specific properties for unmet clinical needs. Understanding of mechanical and biological consequences of the changing gelatin-SNP ratios through this study will shed light on the biomedical applications of iSTB on specific diseases.

Recent advances in nanoengineering cellulose for cargo delivery.

The recent decade has witnessed a growing demand to substitute synthetic materials with naturally-derived platforms for minimizing their undesirable footprints in biomedicine, environment, and ecosystems. Among the natural materials, cellulose, the most abundant biopolymer in the world with key properties, such as biocompatibility, biorenewability, and sustainability has drawn significant attention. The hierarchical structure of cellulose fibers, one of the main constituents of plant cell walls, has been nanoengineered and broken down to nanoscale building blocks, providing an infrastructure for nanomedicine. Microorganisms, such as certain types of bacteria, are another source of nanocelluloses known as bacterial nanocellulose (BNC), which benefit from high purity and crystallinity. Chemical and mechanical treatments of cellulose fibrils made up of alternating crystalline and amorphous regions have yielded cellulose nanocrystals (CNC), hairy CNC (HCNC), and cellulose nanofibrils (CNF) with dimensions spanning from a few nanometers up to several microns. Cellulose nanocrystals and nanofibrils may readily bind drugs, proteins, and nanoparticles through physical interactions or be chemically modified to covalently accommodate cargos. Engineering surface properties, such as chemical functionality, charge, area, crystallinity, and hydrophilicity, plays a pivotal role in controlling the cargo loading/releasing capacity and rate, stability, toxicity, immunogenicity, and biodegradation of nanocellulose-based delivery platforms. This review provides insights into the recent advances in nanoengineering cellulose crystals and fibrils to develop vehicles, encompassing colloidal nanoparticles, hydrogels, aerogels, films, coatings, capsules, and membranes, for the delivery of a broad range of bioactive cargos, such as chemotherapeutic drugs, anti-inflammatory agents, antibacterial compounds, and probiotics. SYNOPSIS: Engineering certain types of microorganisms as well as the hierarchical structure of cellulose fibers, one of the main building blocks of plant cell walls, has yielded unique families of cellulose-based nanomaterials, which have leveraged the effective delivery of bioactive molecules.