We thank Dr Patil and colleagues for their interest in our review, which focused on the role of exosomes during pregnancy under both physiological and pathological conditions. We analysed the information available in the literature with special interest in the isolation methods used to enrich a specific population of extracellular vesicles (EVs) called exosomes.

Interestingly, one of the difficulties was that the majority of groups working on exosomes are using different techniques to isolate and purify these vesicles. We agree that the precise role of exosomes during pregnancies is still not known. Intriguingly, our studies have established that the exosomes released from primary first-trimester trophoblastic cells are very sensitive to the microenvironment milieu (eg, oxygen tensions and D-glucose) ; and exosome-isolated trophoblastic cells have the capacity to regulate biological processes on the target cells (eg, migration and cytokines release) in early states of pregnancies, such as implantation and placentation.

These results suggest that trophoblastic cell-derived exosomes might have a wide range of biological functions during gestation such as uterine spiral arterial remodeling and the maternal vascular/metabolic adaptation to pregnancy. The potential functions of microparticles (MPs)/microvesicles (MVs) during pregnancy has not been studied yet with the same precision. We maintain that one of the biggest problems in determining the specific role of MPs/MVs will be establishing a protocol to isolate MPs/MVs with a high grade of purity. We share and support Dr Patil’s option about more research being required to clarify these matters.

We also agree that because MPs/MVs and exosomes have different origins, they will display different biological activities. Interestingly, our results show that oxygen tension and D-glucose regulate the release of exosomes without a significant effect on the other EVs. Moreover, because MPs/MVs are originating from the plasma membrane, we hypothesize that the mechanisms involved in their release and content selection (eg, incorporation of specific protein and/or microribonucleic acids) are of lower specificity compared with those that regulate exosomal signalling. We agree with the authors that MPs/MVs may be a better biomarker of cell death, but exosomes may be a better representation of the metabolic status of the cell origin.

Another important point is the methods used to quantify EVs. To our knowledge, MP/MV lack specific markers; therefore, the quantification of MPs/MVs in maternal circulation by flow cytometry is not specific. We, as well as others, have established a method to isolate exosomes with a high yield by differential and buoyant density centrifugation.

Finally, we agree with the authors that placenta-derived EVs (including MPs/MVs and exosomes) may reflect placenta status during pregnancy and may be used as early biomarkers of placental dysfunction, opening new opportunities for the prediction of pregnancy-related diseases, such as preeclampsia and gestational diabetes mellitus.