Background: Extracellular vesicles (EVs) are emerging as non-invasive biomarkers in cancer, but their role in monitoring the response to neoadjuvant systemic treatment (NST) in patients with breast cancer remains unclear. This study aimed to assess whether EV concentration and surface marker profiles in plasma reflect treatment response and clinical outcome in patients with early-stage breast cancer receiving NST. Methods: Plasma samples were collected from 59 patients with luminal B-like, HER2-positive, or triple-negative breast cancer before and after NST. EVs were isolated by size exclusion chromatography and characterized by nanoparticle tracking analysis, electron microscopy, Western blotting, and MACSPlex surface marker profiling. Paired samples were available for 29 patients, allowing longitudinal analysis. Results: Patients who achieved pathological complete response (pCR) had significantly lower baseline EV concentrations than those with residual disease. Post-treatment EV levels were also lower in patients who remained free from distant metastasis and had improved breast cancer-specific survival. EV surface marker profiling revealed that CD69, CD29, and CD49e were reduced after NST, whereas CD44 was increased. Notably, EpCAM levels increased specifically in non-PCR patients, suggesting persistent tumor-derived EV release, whereas SSEA-4 levels increased only in patients who achieved pCR. Although EV concentrations and markers differed by subtype and outcome, changes in EV levels following NST were not independently predictive of prognosis. Conclusions: These findings support the potential of plasma-derived EVs as dynamic biomarkers of treatment response, and suggest possible prognostic relevance in breast cancer. Validation in larger, independent cohorts is needed to assess their clinical applicability.

In recent times, with the need for a reduction, refinement, and replacement of in vivo animal testing, there has been an increasing demand for the use of relevant in vitro human cell systems in drug development. There is also a great demand for the replacement of skin tissue in various wounds and burns. Furthermore, human skin cell-based in vitro systems can be used to investigate the side effects (toxicity and irritation) and tissue penetration of topical preparations. In this study, exploratory experiments were performed to produce artificial epidermis using two hydrogel scaffolds, alginate and GelMA C. The amount of keratinocytes added to the matrix (10–50–100 × 10⁶/mL) and the duration of tissue maturation (fresh, 1–3–4 weeks) were optimized in an extensive study. The behavior and structure of the two hydrogels were functionally and morphologically assessed. The permeability order for caffeine in the tested barriers was the following: alginate > GelMA C > cellulose acetate membrane > rat skin. It was concluded that GelMA C matrix provides a more favorable environment for cell survival and tissue differentiation (as demonstrated by histology and immunohistochemistry) than alginate. The 3-week incubation and 50 × 10⁶/mL cell number proved to be the most beneficial in the given system. This study provides data for the first time on the multifactorial optimization of two potential skin substitutes for tissue manufacturing. In order to use these results in tissue engineering, the fabricated artificial epidermis preparations must also be optimized for biocompatibility and from physical and mechanical point of views.

In recent times, with the decline of in vivo animal experiments, there has been an increasing demand for the use of relevant in vitro human cell systems in the development of new drugs. Furthermore, the production of artificial tissues and tissue engineering is also gaining an increasingly important role in regenerative medicine. For example, there is a great demand for the replacement of skin tissue in various acute and chronic wounds and burns. On the other hand, these human skin cell-based in vitro systems can also be used to investigate the side effects (toxicity and irritation) and tissue penetration of topical preparations. In this study, exploratory experiments were performed to produce artificial epidermis using two different hydrogel scaffolds, alginate and GelMA C. Amount of keratinocytes added to the matrix and the duration of tissue maturation were optimized. In addition, the behavior and structure of the two epithelial cell-containing hydrogels were functionally and morphologically tested. Finally, it was concluded that the GelMA C matrix provides a more favorable biological environment for cell survival and tissue differentiation. The 3-week incubation and 50M/mL cell number proved to be the most favorable in the given system. In order to use these results in 3D bioprinting, the fabricated artificial epidermis preparations must be optimized also for biocompatibility and from a physical and mechanical point of view.