Abstract Extracellular vesicles (EVs) derived from stem cells (SCs) have regenerative potential and the possibility of being used in treating chronic diseases. EVs present lower risk of tumorigenicity and easily to isolation and storage. Therefore, this research aims to compare the morphological characteristics of the EVs (up to 150nm) derived from stem cells obtained from canine amniotic membranes in different passages during the in vitro culture. For this, cells from the amniotic membranes were isolated, cultured, and characterized. In order to answer our aim, the number of cells was normalized at each passage to generate conditioned media for EVs separation. The cells were differentiated into adipogenic, chondrogenic, and osteogenic tissue, to characterize these cells as mesenchymal stem cells (MSC). Moreover, flow cytometry analysis was performed and showed that the MSC were positive for CD90, CD105 and negative for CD34, CD45, mesenchymal and hematopoietic markers, respectively. For EVs analysis, MSC in different passages (P0-P2) were culture until 80% of confluence, then the medium was replaced by EVs depleted medium. After 48h, culture medium was collected and centrifuged to separate EVs, followed by nanoparticle tracking analysis. The EVs were also characterized by western blot and transmission electron microscopy (TEM). EVs were positive for Alix and negative for Cytochrome C as well as presented the traditional cup-shape by transmission electronic microscopy. Our results demonstrated that the concentration in the different passages was increased in P0 compared to P1 and P2 (p<0.05). No differences were found in EVs size (P0=132nm, P1=130nm and P2=120nm). Together, these results demonstrate that P0 of MSC is enriched of EVs when compared to later passages, suggesting that this passage would be the best to be applied in pre-clinical tests. Despite that, more studies are necessary to identify the EVs content and how the cells will respond to treatment with them.

Abstract The creation of a genetic resource bank of avian species aims to prevent the decline and fragmentation of wild bird populations, which in turn lead to the loss of genetic diversity and, in more serious cases, the extinction of the most threatened species. In order for the collected genetic material to be stored in a bank and useful when necessary, it is essential to improve the technique ensuring its effectiveness. Thus, our study used feather follicle cells from the domestic gallus species to standardize the technique of cell culture and subsequent cryopreservation. This study aimed to establish a protocol, in vitro, of isolation and primary culture of somatic cells derived from the feather follicle, with the purpose of establishing a cell lineage, and evaluate its viability for the biobank formation. Developing feathers of gallus domesticus were collected at 12, 21 and 34 days of age. The feathers were morphologically analyzed and then we selected the region of the calamus due to the presence of pulp for cell culture and cryopreservation. The results showed that it is possible to find cells with distinct morphology; cells in elliptical shape with central nucleus also in elliptical shape, cells with shape and round nucleus, cells compatible with the fibers of the barbules, cell agglomerates and cells adhered to the bottom of the plate with fibroblastatoid shape. After 24 hours of culture there was the presence of primary culture with 80% of confluence and after cryopreservation the average viability after freezing was 68.8%, with cellular morphologies being maintained. Therefore, we proved the isolation of somatic cells from the follicle of bird’s feathers, suggesting that this is a source of great value, viable and effective for obtaining biological material for the elaboration of a biobank.