Introduction: In the context of drug delivery, mesenchymal stromal cells (MSCs) from bone marrow and adipose tissue have emerged as interesting candidates due to their homing abilities and capacity to carry toxic loads, while at the same time being highly resistant to the toxic effects. Amongst the many sources of MSCs which have been identified, the human term placenta has attracted particular interest due to its unique, tissue-related characteristics, including its high cell yield and virtually absent expression of human leukocyte antigens and co-stimulatory molecules. Under basal, non-stimulatory conditions, placental MSCs also possess basic characteristics common to MSCs from other sources. These include the ability to secrete factors which promote cell growth and tissue repair, as well as immunomodulatory properties. The aim of this study was to investigate MSCs isolated from the amniotic membrane of human term placenta (hAMSCs) as candidates for drug delivery in vitro. Methods: We primed hAMSCs from seven different donors with paclitaxel (PTX) and investigated their ability to resist the cytotoxic effects of PTX, to upload the drug, and to release it over time. We then analyzed whether the uptake and release of PTX was sufficient to inhibit proliferation of CFPAC-1, a pancreatic tumor cell line sensitive to PTX. Results: For the first time, our study shows that hAMSCs are highly resistant to PTX and are not only able to uptake the drug, but also release it over time. Moreover, we show that PTX is released from hAMSCs in a sufficient amount to inhibit tumor cell proliferation, whilst some of the PTX is also retained within the cells. Conclusion: Taken together, for the first time our results show that placental stem cells can be used as vehicles for the delivery of cytotoxic agents.

Background: Ovarian cancer accounts for more deaths than any other cancer of the female reproductive system. Despite standard care, recurrence due to tumor spread and chemoresistance is common, highlighting the need for novel therapies. Mesenchymal stromal cells from the human amniotic membrane (hAMSC) and the intact amniotic membrane (hAM) are promising due to their secretion of tumor-modulating bioactive factors, accessibility from biological waste, and ethical favorability. Furthermore, unlike isolated cells, hAM provides an easier, clinically translatable product. We previously demonstrated that hAMSC can inhibit tumor cell proliferation, both in contact and transwell settings, suggesting that hAMSC secrete bioactive factors able to target tumor cells. This study evaluates the anti-tumor effects of bioactive factors from hAMSC and hAM conditioned medium (CM) on ovarian cancer cells in 2D and 3D models, alone or with paclitaxel. Methods: The impact of CM, alone or with paclitaxel, was tested on ovarian cancer cell proliferation, migration, invasion, and on angiogenesis. Results: hAMSC-CM and hAM-CM inhibited the proliferation and migration in 2D cultures and reduced spheroid growth and invasion in 3D models. Combining CM with paclitaxel enhanced anti-tumor effects in both settings. Conclusions: hAMSC-CM and hAM-CM show therapeutic potential against ovarian cancer, with synergistic benefits when combined with paclitaxel.