Influence of post-thaw culture duration on pregnancy outcomes in frozen blastocyst transfer cycles.

In this study, we aimed to evaluate whether post-thaw culture duration affected the clinical outcomes of frozen blastocyst transfer. This retrospective cohort study included 3,901 frozen-thawed blastocyst transfer cycles. The cohorts were divided into two groups based on the developmental stage (day 5 [D5] and day 6 [D6]) and culture duration after thawing (short culture, 2-6 h; long culture, 18-20 h). Women in the short culture group following D6 blastocyst transfer were further divided into three subgroups depending on the post-thaw culture period (2, 4, and 6 h). The main outcomes, namely live birth rate (LBR), implantation rate (IR), clinical pregnancy rate (CPR), and abortion rate (AR), showed no statistical differences within the groups following D5 blastocyst transfer. Patients in the long culture group had significantly lower IR (35.5 vs. 45.8%, p < 0.001), CPR (45.3 vs. 56.6%, p = 0.001), and LBR (35.5 vs. 48.5%, p < 0.001) but a significantly higher AR (21.6 vs. 14.3%, p = 0.049) following D6 blastocyst transfer than those in the short culture group. However, the data failed to present the superiority of any short culture duration over another on the live birth outcome for embryos vitrified on D6 (adjusted odds ratio [aOR]: 0.96, 95% confidence interval [95% CI]: 0.53-1.73, p = 0.881, for the 4-h vs. 2-h subgroup; aOR: 1.01, 95% CI: 0.68-1.49, p = 0.974, for the 6-h vs. 2-h subgroup). Both post-thaw protocols can be applied to patients with D5 blastocysts. To optimize the pregnancy outcomes following D6 blastocyst transfer, a short culture period is recommended. Any of the three short culture durations (2, 4, and 6 h) can be applied, depending on the workflow of the laboratory.

Human islet mass, morphology, and survival after cryopreservation using the Edmonton protocol.

The aim of this study was to assess recovery, cell death, and cell composition of post-thaw cultured human islets. Cryopreserved islets were provided by the Clinical Islet Transplant Program, Edmonton, Canada. Islets were processed using media prepared in accordance with Pre-Edmonton and Edmonton protocols. Cryopreserved islets were rapidly thawed and cultured for 24 h, 3 d, 5 d, and 7 d, following which they were processed for histology. Islet quantification, integrity, morphology and tissue turnover were studied via hematoxylin and eosin stained sections. Ultrastructure was studied by electron microscopy and endocrine cell composition by immunohistochemistry. Using the Pre-Edmonton protocol, islet recovery was 50.1% and islet survival was 50% at 24 h while for the Edmonton protocol, the islet recovery was 69.4% (p<0.001) and islet survival, 50% at ≈2.5 d. With an increasing culture duration although the physical integrity was retained there was an increasing loss of cohesivity both at light microscopic and at ultrastructure level regardless of the protocols used. Percentage islet survival and tissue turnover correlated negatively with culture duration in both protocols. The Edmonton protocol appears to preserve the islets better. However, culture duration adversely affects islet survival and quality, indicating the need for more optimal cryopreservation and culture techniques.