Aspects of embryo selection and their preparation for the formation of human embryonic stem cells intended for human therapy.

Objective: The work deals with a clinical part of human embryonic stem cell (hESC) research. The aim of the project is the differentiation of somatic cell types, useful in drug development, regenerative medicine and cell therapy. The aim of this work is to enable targeted therapy of yet incurable diseases. The pluripotent hESCs have unlimited self-renewal capacity. This ability is used in therapy to create missing or damaged cells in the human body. It is of interest to develop clinical-grade hESC lines useful in preclinical and clinical studies.

Methods: The derivation of the hESC must respect the legislation of the Czech Republic and the EU. The aim was to develop an informed consent of both donors for donated discarded embryos that are not suitable for treatment by in vitro fertilization according to Directive 2004/23/EC. The FNBs Center for Assisted Reproduction (CAR) participates in oocyte collection, cultivation and cryopreservation of embryos, communication with clients and ensuring the informed consent of embryo donors. A transport protocol and a methodology for handing over the thawed embryos with the original numerical code were developed. Before the embryos are handed over to the ICRC co-authors workplace (CTEF), they are thawed and, if necessary, recultivated to the blastocyst stage; afterwards, assisted hatching is performed.

Results: In the period from January 2018 to July 2020, 138 selected suitable clients were asked for donations, with 52 not responding, 19 terminating and 29 extending the embryo storage. Only 38 clients, i.e. 27.5%, agreed with the usage of their embryos for the preparation of hESCs. In the same period, personal communication with suitable CAR clients took place and another 17 embryo donors were obtained. A total of 160 embryos were obtained from 55 donors aged 26 to 42 years. The embryos were most often frozen in the blastocyst (53 embryos - 33.1%) and morula (74 embryos - 46.3%) stages. Of the 29 genetically examined embryos, only 5 are euploid (17.2%), 2 are mosaic and 22 are aneuploid or with translocations or carriers with a monogenic defect.

Conclusion: We have an informed consent prepared and approved by the Ethics Committee of the Masaryk University and the University Hospital Brno; 160 donated embryos have been selected and secured. A transport protocol and handover methodology are developed. The plan for the transfer of thawed anonymized embryos in the first phase, October - December 2020, includes approximately 5 thawed blastocysts per week with assisted hatching. After their transfer to the CTEF, the embryoblast will be isolated with subsequent cultivation. The established hESCs must meet the specified criteria of safety, stability and pluripotency. We believe that, in accordance with the project plan, we will obtain at least 3 clinical-grade hESC lines, the first created in the Czech Republic, respecting the requirements for Advanced Medicinal Therapy Products   (AMTP).