The effect of different vitrification protocols on cell survival in human ovarian tissue: a pilot study

Background

Vitrification has superseded the slow freezing method for cryopreservation of oocytes, embryos, and sperm, but there are as yet no standard protocols for its use in ovarian tissue cryopreservation (OTC). Published protocols diverge mainly with regard to the extent of supplementation of dimethyl sulfoxide (DMSO) to the vitrification medium, and to the use of an open or closed vitrification system.

We investigated the viability of cells after vitrification/warming, using ovarian tissue of transgender patients, by means of Fluorescence Activated Cells Sorting (FACS), and histomorphological analyses using a DMSO-containing (P1) and a DMSO-free protocol (P2) in an open or closed vitrification setting.

Results

Twelve ovarian samples were donated from female-to-male transgender patients: 6 were vitrified according to protocol 1, the other 6 according to protocol 2. The amount of viable cells was 90.1% (P1) and 88.4% (P2) before vitrification. After vitrification and subsequent warming, viable cells were reduced to 82.9% (P1, p = 0.093) and 72.4% (P2, p = 0.019). When comparing the closed and the open systems, the decline in cell viability from pre- to post-vitrification was significant only for the latter (p = 0.037). Histological examination reveals no significant differences with respect to degenerated follicles before or after vitrification.

Conclusion

These results led us to conclude that a protocol containing DMSO results in a higher viability of ovarian cells than a protocol that uses ethylene glycol as cryoprotective agent in vitrification. The use of an open vitrification system led to significant decline in the rate of viable cells.

Trial registration

NCT03649087, retrospectively registered 28.08.2018.

Placental MRI shows preservation of brain volume in growth-restricted fetuses who suffer substantial reduction of putative functional placenta tissue (PFPT)

OBJECTIVE

Recently, a potentially useful diagnostic approach based on MR diffusion-tensor-imaging (DTI) was reported for the estimation of putative functional placenta tissue (PFPT), thus providing direct information about placental function. Yet, the relation between reduced PFPT and the phenomenon of brain-sparing remains unclear. This study aimed to investigate the relation between brain-sparing and reduced PFPT volume, as found in fetuses with intrauterine growth restriction (IUGR).

METHODS

A total of 40 consecutive patients with a US-based diagnosis of placental IUGR were examined using fetal MRI. A control group of 78 patients who received fetal MRI, due to non-placental pathologies, was established. A somatic energy index was calculated as I_E=1-(V_brain/V_pfpt) from brain and PFPT volumes measured with DTI in both groups. I_E, V_pfpt, and V_brain were analyzed with respect to the gestational week.

RESULTS

V_brain corrected for gestational weeks was no different between both groups, while V_pfpt was significantly reduced in IUGR patients. I_E was significantly different between both groups and indicated a higher V_brain at a comparable V_pfpt.

CONCLUSIONS

Fetuses with IUGR show preserved energetic resources necessary for brain growth. Because I_E drops in IUGR more rapidly as pregnancy progresses, depending on V_pfpt, I_E could prove useful for estimating fetal well-being.