Dr. Jaime Onofre - A new addition to the Walking Egg team

With a growing worldwide interest on the Walking Egg lab system, a new member, Dr. Jaime Onofre, has joined our ranks. With a background in Reproductive Medicine and being a true advocate for global access to fertity care, his task is to promote our project and optimize the Walking Egg system by conducting the required basic and clinical research, next to our set scientists prof. Dr. Vanblerkom and Dr. Van Der Auwera, with the goal to render our system more user-friendly and expand ist use to different fertility centers around the globe.

A summary of his recent PhD dissertation, prepared under the supervision of prof. Dr. Ellen Goossens at the Vrije Universiteit Brussel, can be read below.


Fertility preservation prior to gonadotoxic therapies is an important emerging field. This technology seeks to safeguard future chances of fatherhood in prepubertal patients facing fertility compromising regimens (e.g. chemo- or radiotherapy) by cryopreserving spermatogonial stem cell (SSC)- containing testicular tissue (TT). This procedure is currently offered as an innovative experimental method. This thesis started with an overview of the efficiency of existing TT and testicular cell suspension (TCS) cryopreservation protocols. Efficient cryopreservation protocols for human TT include DMSO, human serum albumin and sucrose, and these are currently applied in the clinic. For TCSs, cryopreservation and cell functionality remained suboptimal. We optimized the cryopreservation protocol for TCSs with immature mouse TCSs aiming for a better cell recovery and fertility restoration after SSC transplantation. The use of an insulate-controlled freezing device and DMEM supplemented with 1.5M DMSO, 10% FCS and 60μM of an anti-apoptotic factor (Z-VAD(Oe)-FMK) as cryomedium resulted in 49% survival of SSCs. For human primary testicular cells, upon freezing, the highest recovery of viable cells was achieved by freezing cells using DMEM supplemented with 1M DMSO, 20% HSA, 30 μM Z-VAD(Oe)-FMK and 200 mM of trehalose in an insulate-controlled slow freezing device. Controlled-rate thawing improved the viability even more. Finally, we compared the ability to restore fertility by SSCT after cryopreserving TCSs with that after cryopreserving TT. Our results highlighted the superiority of TT cryopreservation, as currently applied, to preserve functional SSCs.