A novel isolator-based system promotes viability of human embryos during laboratory processing

In vitro fertilisation (IVF) and related technologies are arguably the most challenging of all cell culture applications. The starting material is a single cell from which one aims to produce an embryo capable of establishing a pregnancy eventually leading to a live birth. Laboratory processing during IVF treatment requires open manipulations of gametes and embryos, which typically involves exposure to ambient conditions. To reduce the risk of cellular stress, we have developed a totally enclosed system of interlinked isolator-based workstations designed to maintain oocytes and embryos in a physiological environment throughout the IVF process. Comparison of clinical and laboratory data before and after the introduction of the new system revealed that significantly more embryos developed to the blastocyst stage in the enclosed isolator-based system compared with conventional open-fronted laminar flow hoods. Moreover, blastocysts produced in the isolator-based system contained significantly more cells and their development was accelerated. Consistent with this, the introduction of the enclosed system was accompanied by a significant increase in the clinical pregnancy rate and in the proportion of embryos implanting following transfer to the uterus. The data indicate that protection from ambient conditions promotes improved development of human embryos. Importantly, we found that it was entirely feasible to conduct all IVF-related procedures in the isolator-based workstations

Layout of the enclosed workstations.

<p>(<b>A</b>) Schematic illustrating the layout of the enclosed workstations showing the workflow from the entry of oocytes into the system until the embryos are replaced in the uterus. The incubators act as pass-through hatches linking adjacent workstations. (<b>B</b>) Schematic diagram showing the layout of 2 enclosed workstations connected by the double-doored incubation chambers. (<b>C</b>) Image showing the main features of an enclosed workstation with a built-in stereomicroscope and incubators. There are separate hatches to allow introduction of consumables and removal of waste. (<b>D</b>) Image shows the control panel for setting the temperature of the incubator, workstation and hotplate and the %CO₂ in the incubator and workstation. An alarm sounds when the environmental parameters deviate from the set-points.</p

Comparison of patient profiles.

<p>Comparison of patient profiles between the open and enclosed systems for women ≤37 years with >10 follicles undergoing their first cycle of treatment. Groups 1 and 2 were processed in the open system but in different laboratories. Group 3 was processed in the enclosed system. There was no statistical difference between groups for any of the parameters measured.</p

Logistic regression model comparing clinical pregnancy rates between the enclosed workstations and conventional open-fronted cabinets.

<p>Cumulative sum of residuals between observed clinical pregnancy rate and that fitted by an overall logistic regression model, plotted against time. During periods of stable performance the plot should have a constant slope: positive when performance is consistently better than average, negative for the opposite. The vertical lines mark the group boundaries. Regions with positive slopes indicate performance consistently better than average, regions with negative slopes indicate the opposite. The start of the third phase, group 3, coincides precisely with a change from a negative to positive slope and a statistically significant improvement in performance (p<0.001). There is no change in performance between the first and second phases or within any phase.</p