## 4 Discussion
In our study, NANOG was not affected, so it does not appear to be related to the effect produced by the tumor secretome (Figure 10a). It has been reported that OCT4 expression increases in inflammatory processes that induce migration [63]. However, OCT4 remained constant in all conditions, indicating that OCT4 is not involved in the changes observed in MSCs in the presence of a tumor secretome. IL-10 is a cytokine involved in modulating inflammation [61], although it has been related to tumoral growth [64]. In our work, secretomes did not affect proliferation, so the role that IL-10 probably had is related to the counteraction of inflammatory effects produced by the tumoral secretome. It has been observed that the downregulation of TGF-\(\beta\) inhibits the motility of cancer cells. However, in cells cultivated in the presence of a secretome, TGF-\(\beta\) increases, but motility is decreased, so the results in this study cannot be related to tumoral transformation [65]. All the results together suggest that the tumoral environment induces the inhibition of proliferation and significant changes in the disposition of actin fibers, which, in turn, alter the morphology of MSCs and directly affect bioimpedance values. Changes in the magnitude and phase signatures of bioimpedance indicate modifications in the volumetric cell structure and cell membrane thickness, respectively. These logarithmic shifts in the bioimpedance parameters appear to correlate with morphological and cytoskeletal changes,as well as with alterations in actin fiber organization, which promote the formation of microstructures on the membrane surface. Interestingly, TGF-\(\beta\) expression does not appear to be related to tumor transformation but rather seems to represent a natural anti-inflammatory response counteracting the tumor stimuli (secretome). Future studies could explore other molecules associated with bioimpedance changes to better understand the different cellular responses involved. These molecular analyses not only explained the observed morphological changes but also provided detailed information on the signaling pathways involved in the response to the tumor environment. The results obtained underline the importance of integrating both morphological and molecular characterization to obtain a more complete picture of cellular responses. This work suggests that the secretome derived from breast cancer tumor cells (MCF-7 line) induces early morphological changes in MSCs. These changes are associated with the tumor environment but are not indicative of malignancy. This finding is highly relevant to regenerative medicine, as MSCs are widely used in therapies that often overlook the potential influence of tumor environments, which could alter their morphology and, consequently, their migratory capacity. However, the observed changes are more likely related to anti-inflammatory responses rather than cellular transformation. On the other hand, it was possible to prove that bioimpedance spectroscopy is a sensitive technique that is helpful in detecting early subtle changes. This demonstrates that bioimpedance represents an emerging, fast, and inexpensive technique that does not require a large number of cells for analysis [66]. These results, using knowledge of biomedical engineering, are pioneering in describing the short-term morphological changes in MSCs produced by a tumor secretome. However, an area for improvement is the absence of a secretome from non-tumor cells as a control. Including this in future experiments will help determine the tumor-specific effects on MSC morphology and migration. Since the main criteria of this study focus on evaluating morphology, future studies will include proteomic analyses to further characterize the secretome and validate these findings, as well as additional molecular studies to determine their safety for use in regenerative medicine. Conceptualization, A.L.S.-C. and G.G.-I.