Biology subjects

Oliveira, A. C.

Publications and source records attributed to Oliveira, A. C..

3 recordsLinked to original sources

bioRxiv2019

The subtle balance of insulin and thyroxine on survival and development of primordial follicles cultured in vitro enclosed in ovarian tissue

Thyroid hormones have presented a positive hormonal interaction on follicular development of secondary follicles and oocytes from antral follicles; however, the effect of thyroid hormones on primordial follicles is unclear. Here we investigated the in vitro effects of combined insulin and thyroxine on caprine primordial follicle survival and development. Ovarian tissues were cultured for 1 or 7 days using 10 ng/ml (low) or 10 {micro}g/ml (high) insulin in the absence or presence of thyroxine at 0.5, 1 or 2 {micro}g/ml. Thereafter, follicular survival and development, gene expression related to apoptosis (Bcl2/Bax), insulin and thyroid receptors, and estradiol and reactive oxygen species production were evaluated. In low-insulin conditions, supplementation with 2 {micro}g/ml thyroxine maintained follicular survival similar to non-cultured control, while 0.5 {micro}g/ml thyroxine enhanced the survival (P<0.05) in comparison to thyroxine-free treatment. Only treatments containing low-insulin and thyroxine at 0.5 or 2 {micro}g/ml increased (P<0.05) reactive oxygen species production from day 1 to day 7. Contrarily to high-insulin containing medium, the presence of thyroxine in low-insulin medium yielded higher stromal cell density (P<0.05). There were higher (P<0.05) estradiol production and Bcl2/Bax ratio in low-insulin versus high-insulin treatments on day 1 and 7, respectively. High levels of both insulin and thyroxine showed better follicular development (P<0.05), yielding great follicle and oocyte diameter. Finally, the high-insulin level led to insulin and thyroid receptors expression reduction as compared to non-cultured control. In conclusion, the combination of low concentrations of insulin and thyroxine better maintained follicle survival, while high levels ensured better follicular development.

physiology↗

bioRxiv2019

From 3D to 3D: isolation of mesenchymal stem/stromal cells into a three-dimensional human platelet lysate matrix

Mesenchymal stem/stromal cells (MSCs) are considered an important candidate in cell therapy and tissue engineering approaches. The culture of stem cells in a 3D environment is known to better resemble the in vivo situation and to promote therapeutically relevant effects in isolated cells. Therefore, the aim of this study was to develop an approach for the isolation of MSCs from adipose tissue into a 3D environment. Furthermore, the use of cryoprotective medium for cryopreservation of whole adipose tissue was evaluated. For the isolation of MSCs, a novel human platelet lysate-based hydrogel was used as matrix and the migration, yield, viability and metabolic activity of cells from the 3D matrix were compared to cells from 2D explant culture. Also, the surface marker profile and differentiation capacity of MSCs from the 3D matrix were evaluated and compared to MSCs from isolation by enzymatic treatment. We found that cryopreservation of whole adipose tissue is feasible, and therefore adipose tissue can be stored and is available for MSC isolation on demand. Also, we demonstrate the isolation of MSCs into the 3D matrix and that cells from this condition display a similar phenotype and differentiation capacity like MSCs derived by traditional isolation procedure. The presented approach allows, for the first time, to isolate MSCs directly into a soft 3D hydrogel environment, avoiding any contact to a 2D plastic culture surface.\n\nSignificance StatementIn this paper we present a new method for the isolation of mesenchymal stem cells. Usually, these cells grow on two-dimensional plastic surfaces which is far away from their physiologic environment. Our new method allows for the first time the direct outgrowth of cells from primary tissue into a three-dimensional environment, avoiding any contact to a two-dimensional plastic surface. In future, this will allow an entirely three-dimensional in vitro cultivation of stem cells. Using 3D isolated cells will probably also increase the physiologic relevance of in vitro models.

cell biology↗

bioRxiv2019

Yellow Fever Vaccine Protects Resistant and Susceptible Mice Against Zika Virus Infection

Zika virus (ZIKV) emerged as an important infectious disease agent in Brazil in 2016. Infection usually leads to mild symptoms but severe congenital neurological disorders and Guillain-Barre syndrome have been reported following ZIKV exposure. The development of an effective vaccine against Zika virus is a public health priority, encouraging the preclinical and clinical studies of different vaccine strategies. Here, we describe the protective effect of an already licensed attenuated yellow fever vaccine (17DD) on type-I interferon receptor knockout mice (A129) and immunocompetent (BALB/c) mice infected with ZIKV. Yellow fever virus vaccination results in robust protection against ZIKV, with decreased mortality in the A129 mice, a reduction in the cerebral viral load in all mice, and weight loss prevention in the BALB/c mice. Despite the limitation of yellow fever (17DD) vaccine to elicit antibody production and neutralizing activity against ZIKV, we found that YF immunization prevented the development of neurological impairment induced by intracerebral virus inoculation in adult. Although we used two vaccine doses in our protocol, a single dose was protective, reducing the cerebral viral load. Different Zika virus vaccine models have been tested; however, our work shows that an efficient and certified vaccine, available for use for several decades, effectively protects mice against Zika virus infection. These findings open the possibility for using an available and inexpensive vaccine to a large-scale immunization in the event of a Zika virus outbreak.

immunology↗