Taieba Tuba Rahman

Understanding human’s responses to extreme environments holds significant importance for space exploration, deep-sea research, and environmental adaptation. Traditionally, human subjects were used to study humans’ responses to extreme environments. The main limitations of this approach include the inability to independently investigate specific cellular mechanisms, ethical and safety constraints, limited experimental controllability, and inter-individual variability that complicates mechanistic interpretation. Another approach is to study humans’ responses at the cellular level using 2D culture. This approach often exhibits limited reproducibility due to its inability to recapitulate physiologically relevant microenvironments. Bioprinting can enable studies on human’s responses at the cellular level and within 3D environments. One way is to study human cells’ responses to localized and transient extreme environments created during printing. Another way is to expose 3D printed samples (embedded with human cells) to extreme environments. However, the literature does not contain comprehensive review papers to discuss the prospects and limitations of bioprinting for investigating human cells’ responses to extreme environments. This review paper aims to fill this gap in the literature. It begins with a brief description of the effects of extreme environments on human health and summarizes reported studies on cells’ responses to extreme environments. Afterward, it discusses the prospects and limitations of the two ways of using bioprinting to investigate cells’ responses to extreme environments. Finally, it concludes with identifying knowledge gaps and proposing research directions in the application of bioprinting to study human cells’ responses to extreme environments.

This study investigates how different levels of extrusion pressure during 3D printing affect the cell viability of human bronchial epithelial (HBE) cells embedded in printed samples. In this study, samples were printed at three levels of extrusion pressure. The cell viability was assessed through live/dead staining via microscopic imaging. The results show that increasing the extrusion pressure from 50 to 100 kPa led to a higher degree of cell death. These results demonstrate how the extrusion pressure affects the viability of HBE cells and provide a basis for future studies on pressure-induced responses in respiratory tissues.

In this preliminary study, the long-term effects of calcium chloride crosslinking concentration on viability of 16HBE14o- human bronchial epithelial cells embedded in alginate-extracellular matrix (ECM) or alginate–methylcellulose–ECM hydrogels have been investigated. There is currently a limited understanding regarding the effects of crosslinking solution concentration on lung epithelial cells embedded in hydrogel. Furthermore, the effects of calcium chloride concentration in crosslinking solutions on other cell types have not been reported regarding whether the addition of viscosity and stiffness tuning agents such as methylcellulose will alter the responses of cells to changes in calcium chloride concentration in crosslinking solutions. While there were no significant effects of calcium chloride concentration on cell viability in alginate–ECM hydrogels, there is a decrease in cell viability in alginate–methylcellulose–ECM hydrogels crosslinked with 300 mM calcium chloride crosslinking solution. These findings have implications in the maintenance of 16HBE14o- 3D cultures with respect to the gelation of alginate with high concentrations of ionic crosslinking solution.

This paper reports an experimental study on the effects of extreme temperature on human bronchial epithelial (HBE) cells encapsulated in 3D printed samples. Well plates of the 3D printed samples were exposed to three levels of temperature (37 °C, 45 °C, and 55 °C, respectively) for a duration of 10 min. Cells’ responses, specifically cell viability and oxidative stress, were quantified using Hoechst 33342, Sytox, and Mitosox stains, with intensity measurements obtained via a plate reader. In addition, cell viability was assessed through microscopic imaging of the 3D printed samples. Experimental results demonstrated that the temperature increase from 37 °C to 55 °C significantly reduced nuclear integrity as observed through Hoechst 33342 intensity, while increased Sytox intensity reflected a higher degree of cell death. Furthermore, cells exposed to 45 °C and 55 °C exhibited decreased cell viability and elevated mitochondrial oxidative stress. These findings offer valuable insights into the effects of extreme temperature on HBE cells, establishing a foundation for future research into how respiratory tissues respond to thermal stress. This research can potentially advance the knowledge regarding effects of heat exposure on the respiratory system.

This paper reports an experimental study on the compatibility of human bronchial epithelial (HBE) cells in a collagen–alginate bioink. The compatibility was assessed using the culture well method with three bioink compositions prepared from a 10% alginate solution and neutralized TeloCol-10 mg/mL collagen stock solution. Cell viability, quantified by (live cell count—dead cell count)/live cell count within the HBE cell-laden hydrogel, was evaluated using the live/dead assay method from Day 0 to Day 6. Experimental results demonstrated that the collagen–alginate 4:1 bioink composition exhibited the highest cell viability on Day 6 (85%), outperforming the collagen–alginate 1:4 bioink composition and the alginate bioink composition, which showed cell viability of 75% and 45%, respectively. Additionally, the live cell count was highest for the collagen–alginate 4:1 bioink composition on Day 0, a trend that persisted through Days 1 to 6, underscoring its superior performance in maintaining cell viability and promoting cell proliferation. These findings show that the compatibility of HBE cells with the collagen–alginate 4:1 bioink composition was higher compared with the other two bioink compositions.

To combat climate change, one approach is to manufacture products from biomass-fungi composite materials instead of petroleum-based plastics. These products can be used in packaging, furniture, and construction industries. A 3D printing-based manufacturing method was developed for these biomass-fungi composite materials, eliminating the need for molds, and enabling customized product design. However, previous studies on the 3D printing-based method showed significant shrinkage of printed samples. In this paper, an approach is proposed to reduce the shrinkage by incorporating ionic crosslinking into biomass-fungi composite materials. This paper reports two sets of experiments regarding the effects of sodium alginate (SA) and calcium chloride (CaCl₂) on fungal growth and fungal viability. The first set of experiments was conducted using Petri dishes with fungi isolated from colonized biomass-fungi material and different concentrations of SA and CaCl₂. Fungal growth was measured by the circumference of fungal colonies. The results showed that concentrations of SA and CaCl₂ had significant effects on fungal growth and no fungal growth was observed on Petri dishes with 15% CaCl₂. Some of these Petri dishes were also observed under confocal microscopy. The results confirmed the differences obtained by measuring the circumference of fungal colonies. The second set of experiments was conducted using Petri dishes with biomass-fungi mixtures that were treated with different concentrations of SA and exposure times in a CaCl₂ (crosslinking) solution. Fungal viability was measured by counting colony-forming units. The results showed that the addition of the SA solution and exposure times in the crosslinking solution had statistically significant effects on fungal viability. The 2SA solution was prepared by dissolving 2 g of SA in 100 mL of water, the 5SA solution was prepared by dissolving 5 g of SA in 100 mL of water, and the crosslinking solution was prepared by dissolving 5 g of CaCl₂ in 100 mL of water. The results also showed that fungal viability was not too low in biomass-fungi mixtures that included 2SA solution and were exposed to the crosslinking solution for 1 min.

Bioprinting using algae cells has many potential applications including tissue engineering, environmental engineering, contaminant removal from water, and establishing space habitats. In extrusion-based bioprinting, bioink needs to be crosslinked after being extruded from the nozzle for printed constructs to first achieve and then maintain adequate shape fidelity. Crosslinking methods used in reported studies on algae-contained bioinks include both photo-crosslinking and ionic crosslinking. This paper reports a preliminary study where the coaxial nozzle-based in situ ionic crosslinking method was used in bioprinting of algae cells without additional crosslinking of printed samples for the first time. In comparison with photo-crosslinking, in situ ionic crosslinking can minimize bioink preparation time and complexity, eliminate cells’ exposure to ultraviolet radiation, and reduce the number of post-printing steps. In this preliminary study, the bioink was an alginate solution containing algae (Chlorella vulgaris) cells, and the crosslinking solution was a calcium chloride solution. The coaxial nozzle had two nozzles: inner and outer nozzles. In printing, the bioink was delivered through the outer nozzle while the crosslinking solution was delivered through the inner nozzle. The shape of the printed samples was a square block with dimensions of 30 × 30 × 10 mm. It was observed that, 9 days after printing, the algae cells grew within the printed samples, and the samples could keep their shapes relatively well. Many knowledge gaps exist regarding the effects of input variables in bioprinting of algae cells using this method. This paper discusses future research directions to fill these knowledge gaps.

Agriculturally derived biowastes can be transformed into a diverse range of materials, including powders, fibers, and filaments, which can be used in additive manufacturing methods. This review study reports a study that analyzes the existing literature on the development of novel materials from agriculturally derived biowastes for additive manufacturing methods. A review was conducted of 57 selected publications since 2016 covering various agriculturally derived biowastes, different additive manufacturing methods, and potential large-scale applications of additive manufacturing using these materials. Wood, fish, and algal cultivation wastes were also included in the broader category of agriculturally derived biowastes. Further research and development are required to optimize the use of agriculturally derived biowastes for additive manufacturing, particularly with regard to material innovation, improving print quality and mechanical properties, as well as exploring large-scale industrial applications.

Microalgae can be part of the solution to the global food crisis, as they have high nutritional values. Recently, 3D printing of microalgae-enriched snacks has been reported with the capability to customize nutritional profiles, shapes, and textures of the snacks. Because the process parameters of extrusion-based 3D printing affect the printability of cookie dough, it is important to know the levels of process parameters leading to continuous extrusion. This study investigated feasible regions of printing process parameters for continuous extrusion of microalgae (Arthrospira Platensis) enriched cookie dough. The process parameters studied were nozzle diameter, printing speed, and air pressure. The feasible regions were determined by visual inspections of printed strands. The results show that, for smaller nozzle diameters and higher printing speeds, higher air pressures are required to ensure continuous extrusion. The identified feasible regions from this study would be helpful when deciding the appropriate nozzle diameter, printing speed, and air pressure to print microalgae-enriched cookie dough and other materials with similar rheological properties in extrusion-based 3D printing.