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Timeva T.,Ob Gyn Hospital | Shterev A.,Ob Gyn Hospital | Kyurkchiev S.,Institute of Reproductive Health
Journal of Reproduction and Infertility | Year: 2014

The success rate of reproductive treatment methods depends on many different factors. The most important and discussed ones in the literature are maternal age, the causes of infertility, the ovarian response to stimulation, the influence of the male factor and sperm quality, embryo quality and the various uterine pathologies. Some couples fail repeatedly after transferring good quality embryos without any obvious reason and this becomes a major continuing problem after IVF/ICSI procedures. It can be speculated that in these couples, insufficiency of the endometrium might be a possible reason for implantation failure. This review article summarized current literature describing the consecutive endomertial procedures involved in successful embryo implantation. It is believed that efforts to align criteria for definition of recurrent implantation failure (RIF) and attempts to classify different RIF types would develop guidelines for treatment procedures which would result in an increase in patients' opportunities to conceive. © 2014, Avicenna Research Institute. All rights reserved.


Bochev I.,Ob Gyn Hospital Dr Shterev | Belemezova K.,Tissue bank BULGEN | Shterev A.,Ob Gyn Hospital Dr Shterev | Kyurkchiev S.,Tissue bank BULGEN | Kyurkchiev S.,Institute of Reproductive Health
Journal of Assisted Reproduction and Genetics | Year: 2016

Purpose: Along with comparative investigation of the decidualization potential and IL-6 secretion by fresh and frozen ESCs, we also aimed to evaluate the effectiveness of co-culture systems based on fresh or frozen ESCs in terms of clinical pregnancy rates. Methods: Outcome analysis of a total of 215 IVF cycles with co-culture with fresh or frozen ESCs was performed. Endometrial tissue was obtained from 17 healthy donors. Concentrations of secreted prolactin, IGFBP-1, and IL-6 in conditioned media from cultured fresh and frozen ESCs (decidualized or not) were measured using ELISA or ECLIA. Results: Embryo co-culture with frozen ESCs resulted in a much lower pregnancy rate compared to the alternative system using fresh ESCs. Furthermore, cultivated frozen ESCs showed considerably decreased release of prolactin, IGFBP-1, and IL-6 compared to fresh ESCs, indicating that cryopreservation negatively affects their decidualization potential and cytokine production. Conclusions: Altogether, this data illustrates the need for optimization and improvement of the existing autologous endometrial co-culture systems. © 2016 Springer Science+Business Media New York


Stoyanova E.,Bulgarian Academy of Science | Mourdjeva M.,Bulgarian Academy of Science | Kyurkchiev S.,Institute of Reproductive Health | Kyurkchiev S.,Obstetrics Gynecology hospital Dr Shterev
Biotechnology and Biotechnological Equipment | Year: 2015

Induced pluripotent stem cells (iPSC) are ‘artificial’ stem cells that can be obtained by reprogramming of somatic cells. iPSC display properties, typical for embryonic stem cells (ESC) in terms of morphology, proliferation, differentiation capacity, genomic and epigenomic states. The generation of iPSC from somatic cells not only reduces some of the problems, connected with ESC, but also provides a potential human in vitro model for disease modelling and drug development. The current techniques for the production of iPSC are ineffective and often incomplete. ?btaining of extremely low amount of fully reprogrammed cells or iPSC is one of the current problems. The low efficiency of iPSC generation is a significant barrier for fast and accurate screening and makes the colony isolation time consuming and costly. In order to develop the full potential of iPSC technology, scientists are searching for new and more effective methods for generation and isolation of iPSC. Here, we report a method that could help for the isolation of iPSC cells in a short period after reprogramming. The method involves a selection of cells, based on the expression of OCT4 and a surface pluripotent marker TRA-1-60. Reprogrammed cells, isolated by this method, expressed pluripotent markers OCT4, SOX2, NANOG, KLF4 and TRA-1-60 and were able to differentiate into the three germ layers in vitro. © 2015 The Author(s). Published by Taylor & Francis.

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