This study is preliminary to an experiment to be performed onboard the International Space Station (ISS) and on Earth to investigate how low gravity influences the healing of sutured human skin and vein wounds. Its objective was to ascertain whether these tissue explants could be maintained to be viable ex vivo for long periods of time, mimicking the experimental conditions onboard the ISS. We developed an automated tissue culture chamber, reproducing and monitoring the physiological tensile forces over time, and a culture medium enriched with serelaxin (60 ng/mL) and (Zn(PipNONO)Cl) (28 ng/mL), known to extend viability of explanted organs for transplantation. The results show that the human skin and vein specimens remained viable for more than 4 weeks, with no substantial signs of damage in their tissues and cells. As a further clue about cell viability, some typical events associated with wound repair were observed in the tissue areas close to the wound, namely remodeling of collagen fibers in the papillary dermis and of elastic fibers in the vein wall, proliferation of keratinocyte stem cells, and expression of the endothelial functional markers eNOS and FGF-2. These findings validate the suitability of this new ex vivo organ culture system for wound healing studies, not only for the scheduled space experiment but also for applications on Earth, such as drug discovery purposes.

In the process of tissue engineering, several types of stresses can influence the outcome of tissue regeneration. This outcome can be understood by designing hydrogels that mimic this process and studying how such hydrogel scaffolds and cells behave under a set of stresses. Here, a hydrogel formulation is proposed to create biomimetic scaffolds suitable for fibroblast cell culture. Subsequently, we examine the impact of external stresses on fibroblast cells cultured on both solid and porous hydrogels. These stresses included mechanical tension and altered-gravity conditions experienced during the 83rd parabolic flight campaign conducted by the European Space Agency. This study shows distinct cellular responses characterized by cell aggregation and redistribution in regions of intensified stress concentration. This paper presents a new biomimetic hydrogel that fulfills tissue-engineering requirements in terms of biocompatibility and mechanical stability. Moreover, it contributes to our comprehension of cellular biomechanics under diverse gravitational conditions, shedding light on the dynamic cellular adaptations versus varying stress environments.

Background/Objectives: Many lasers applied in skin rejuvenation protocols show emissions with wavelengths falling in the red or near-infrared (NIR) bands. To obtain further in vitro data on the potential therapeutic benefits regarding rejuvenation, we employed a 675 nm laser wavelength on cultured human dermal fibroblasts to understand the mechanisms involved in the skin rejuvenation process’s signaling pathways by analyzing cytoskeletal proteins, extracellular matrix (ECM) components, and membrane integrins. Methods: Normal human dermal fibroblasts (NHDFs) were irradiated with a 675 nm laser 24 h after seeding, and immunofluorescence microscopy and Western blotting were applied. Results: The results demonstrate that the laser treatment induces significant changes in human dermal fibroblasts, affecting cytoskeleton organization and the production and reorganization of ECM molecules. The cell response to the treatment appears to predominantly involve paxillin-mediated signaling pathways. Conclusions: These changes suggest that laser treatment can potentially improve the structure and function of skin tissue, with interesting implications for treating skin aging.

Background: The multifactorial pathogenesis of bronchopulmonary dysplasia (BPD) includes prematurity, inflammation, and oxidative stress. Photobiomodulation therapy (PBMT) using near-infrared (NIR) laser sources was found to have anti-inflammatory effects in several respiratory disorders. Our aim was to evaluate whether PBMT could reduce inflammation in an in vitro model of BPD. Materials and Methods: Precision-cut lung slices (PCLSs) from premature rabbits were exposed to lipopolysaccharide (LPS) and treated with three PBMT protocols (A, B, and C) differing for the treatment parameter such as fluence (energy delivered per unit area, laser A: 7.09, laser B: 7.41, laser C: 7.01 J/cm²) and exposure time (25, 20, 12 s, respectively). The expression level of TNFα and IL-6 was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR) after 2 or 6 h from PBMT. Results: PBMT protocols A and B reduced IL-6 and TNFα mRNA at both timepoints, although the effect was less pronounced after 6 h than after 2 h. Furthermore, protocol A, which involved intermediate fluence and longer laser exposure, was more effective than protocol B. Conclusions: PBMT with NIR laser sources has an effective anti-inflammatory effect in an in vitro model of BPD, such as PCLSs from premature rabbits pretreated with LPS. These encouraging results support the planning of further studies in animal models of BPD and help identify the most effective PBMT protocol to use.