Comparison of the biomechanical characteristics of human ovarian tissue after vitrification versus slow freezing.

Abstract

Objective: Numerous studies have compared ovarian tissue cryopreservation methods, including slow freezing/rapid thawing (SF/RT) and vitrification/warming (V/W), focusing on morpho-functional status, follicle density, stromal cell integrity, and gene expression during in vitro culture. However, results remain inconclusive. This study aims to evaluate the effects of SF/RT and V/W on the ovarian cortex's biomechanical properties.

Methods: Human ovarian biopsies were taken from five women between 32 and 45 years undergoing laparoscopic surgery for tubal sterilization. For each patient, one small sample of fresh tissue was used as control, and the remaining tissue were vitrified or frozen by slow freezing method. The tissue stiffness of the cryopreserved samples at the micrometer scale was measured by Atomic Force Microscopy after thawing and warming, depending of the cryopreservation method.

Results: The median stiffness of the ovarian cortex was 3670.00 Pa (Pascal) (IQR 2146.4) in the control group. After cryopreservation, the median stiffness slightly decreased to 1305.90 Pa (IQR 503.51) with SF/RT and to 2284.50 Pa (IQR 3314.40) with V/W. General linear model analysis revealed no significant effect of cryopreservation method on the ovarian cortex stiffness (F=2.750, p=0.071). No significant differences were observed based on the intra-sample zone studied by AFM. However, a significant inter-patient effect on tissue stiffness was identified (F=3.958, p=0.006).

Conclusions: The study findings suggest that ovarian tissue freezing methods do not have a relevant impact on functional aspects of the extracellular matrix (ECM), suggesting that given the logistical advantages of vitrification, this technique should be prioritized.