PP-6 Integration and validation of the ex vivo human placenta perfusion model

Abstract

Background Pregnant women and their fetuses are or-phan populations with respect to knowledge on safety and efficacy of drugs. It is estimated that over 90% of pregnant women uses over-the-counter or prescription medication.1 Albeit, data on transplacental transfer or fetal effects are still lacking for most of the medicines and food supplements. The ex vivo human placenta perfusion model is an effective and non-invasive method to study transplacental passage of drugs and environmental com-pounds in humans.2 It is the only method that retains the full structure of a full term human placenta, making it possible to study transplacental passage without harm-ing the foetus or the mother.3 Due to many challenges and its high complexity it remains difficult to incorporate it routinely into laboratories. Methods A step-by-step protocol for the implementa-tion and validation of a closed-closed ex vivo perfusion model was developed. Different quality controls were implemented to ensure the integrity, viability and func-tionality of the method: (i). Antipyrine is a small drug molecule that does not bind to proteins and that passes the placental barrier by passive diffusion; It was used here to determine ‘overlap’ (solute exchange) between foetal and maternal circulation; (ii) the pressure and the flow rate in the foetal circulation as a marker for leakage; (iii) pH and glucose consumption were implemented as a marker for tissueviability. Results In total 89 placentas were collected of which 34 placentas were successfully perfused with antipyrine and fulfilled all quality control measurements. A foe-tal/maternal antipyrine concentration ratio of 0.75 was reached within 89±21 min, while 210 min were required to achieve equilibrium. The foetal pressure remained un-der 70 mmHg during the entire experiment. The end foe-tal flow was 98% of the foetal starting flow. The average glucose consumption was 0.30±0.15 µmol/min/g. Every 30 min the maternal pH declined to 7.29±0.06 and was adjusted to 7.4. The foetal pH stayed stable at 7.30±0.05. Conclusion Based on the multiple quality control mea-surements, the described method of a closed human ex-vivo placenta perfusion model was validated. The success rate (38%) was more than twice the success rate reported in literature (15%).