Integration and validation of the ex vivo human placenta perfusion model

The ex vivo human placenta perfusion model is an effective and non-invasive method to study transplacental passage of drugs and environmental compounds in humans. Due to many challenges and its high complexity it remains difficult to incorporate it routinely into laboratories.

This article describes a step-by-step protocol for the implementation and validation of a closed-closed ex vivo perfusion model. Antipyrine, a small molecule that passes the placental barrier by passive diffusion, was used as a measurement of overlap between foetal and maternal circulation. The pressure and the flow rate in the foetal circulation, glucose consumption and pH were implemented to ensure the integrity, viability and functionality of the method.

In total 89 placenta were collected of which 34 placentas were successfully perfused with antipyrine and fulfilled all quality control measurements. A foetal/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 under 70 mmHg during the entire experiment. The end foetal 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.

Based on the assessment of multiple quality control measurements, 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%).