Placental transfer of bromocriptine in an ex vivo human placental perfusion model

Ensemble learning for predicting ex vivo human placental barrier permeability

Background

The placental barrier protects the fetus from exposure to some toxicants and is vital for drug development and risk assessment of environmental chemicals. However, in vivo experiments for assessing the placental barrier permeability of chemicals is not ethically acceptable. Although ex vivo placental perfusion methods provide good alternatives for the assessment of placental barrier permeability, the application to a large number of test chemicals could be time- and resource-consuming. Computational prediction models for ex vivo placental barrier permeability are therefore desirable.

Methods

A total of 87 chemicals and corresponding 1444 physicochemical properties were divided into training and test datasets. Three types of algorithms including linear regression, random forest, and ensemble models were applied to develop prediction models for ex vivo placental barrier permeability.

Results

Among the tested models, the ensemble model integrating the previous two methods performed best for predicting ex vivo human placental barrier permeability with correlation coefficients of 0.887 and 0.825 when considering the applicability domain. An additional test on seven newly curated chemicals from the literature showed a good correlation coefficient of 0.879 which was further improved to 0.921 by considering the variation of experiments.

Conclusion

In this study, the first valid predicting model for ex vivo human placental barrier permeability was developed following the OECD guideline. The model is expected to be useful for assessing the human placental barrier permeability and can be integrated with developmental toxicity prediction models for investigating the toxic effects of chemicals on the fetus.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-022-04937-y.

Italian Association of Clinical Endocrinologists (AME) and International Chapter of Clinical Endocrinology (ICCE). Position statement for clinical practice: prolactin-secreting tumors

Prolactinomas are the most frequent pituitary adenomas. Prolactinoma may occur in different clinical settings and always require an individually tailored approach. This is the reason why a panel of Italian neuroendocrine experts was charged with the task to provide indications for the diagnostic and therapeutic approaches that can be easily applied in different contexts. The document provides 15 recommendations for diagnosis and 54 recommendations for treatment, issued according to the GRADE system. The level of agreement among panel members was formally evaluated by RAND-UCLA methodology. In the last century, prolactinomas represented the paradigm of pituitary tumors for which the development of highly effective drugs obtained the best results, allowing to avoid neurosurgery in most cases. The impressive improvement of neurosurgical endoscopic techniques allows a far better definition of the tumoral tissue during surgery and the remission of endocrine symptoms in many patients with pituitary tumors. Consequently, this refinement of neurosurgery is changing the therapeutic strategy in prolactinomas, allowing the definitive cure of some patients with permanent discontinuation of medical therapy.

Barusiban, a selective oxytocin receptor antagonist: placental transfer in rabbit, monkey, and human†

The use of drugs in pregnancy always raises concerns regarding potential fetal exposure and possible adverse effects through their accumulation in fetal tissues and organs. Barusiban is an oxytocin antagonist under development for potential use as tocolytic in preterm-labor patients. It displays greater affinity for the oxytocin receptor compared to vasopressin V1A receptor and would thus not interfere with vasopressin-induced effects of the V1A receptor. Barusiban placental transfer was determined in the rabbit and cynomolgus monkey and in an ex vivo human cotyledon model. In the rabbit, there was an approximately 5% transfer of barusiban from the maternal to the fetal blood, without significant accumulation in any of the investigated fetal tissues. In the cynomolgus monkeys, the mean fetal plasma barusiban concentration was 9.1% of the maternal level. This was similar to the percentage of barusiban transfer in the human placental single cotyledon, which once equilibrated ranged between 9.3 and 11.0% over the observation period. The transfer of the small-molecule antipyrine as a comparator in this human model was approximately three times greater. The similarity in the degree of transfer in the cynomolgus monkey and human cotyledon, while being less in the rabbit, may reflect the species-specific placental barrier structure between the maternal and fetal compartments. In conclusion, limited placental transfer of barusiban occurred in all three models. The similarity of barusiban transfer in the cynomolgus and the human placental single cotyledon suggests the latter ex vivo model to be useful in assessing future drug candidates to be used in pregnant women.

Development of an Organ-on-a-Chip-Device for Study of Placental Pathologies

The human placenta plays a key role in reproduction and serves as a major interface for maternofetal exchange of nutrients. Study of human placenta pathology presents a great experimental challenge because it is not easily accessible. In this paper, a 3D placenta-on-a-chip model is developed by bioengineering techniques to simulate the placental interface between maternal and fetal blood in vitro. In this model, trophoblasts cells and human umbilical vein endothelial cells are cultured on the opposite sides of a porous polycarbonate membrane, which is sandwiched between two microfluidic channels. Glucose diffusion across this barrier is analyzed under shear flow conditions. Meanwhile, a numerical model of the 3D placenta-on-a-chip model is developed. Numerical results of concentration distributions and the convection-diffusion mass transport is compared to the results obtained from the experiments for validation. Finally, effects of flow rate and membrane porosity on glucose diffusion across the placental barrier are studied using the validated numerical model. The placental model developed here provides a potentially helpful tool to study a variety of other processes at the maternal-fetal interface, for example, effects of drugs or infections like malaria on transport of various substances across the placental barrier.

Inter-individual variations and modulators of MDR1 transport activity in human placenta

INTRODUCTION

ATP binding cassette (ABC) membrane transporter multidrug resistance 1 (MDR1) is one of the most important efflux transporters in the human placenta protecting the fetus from exposure to xenobiotic toxicity. Recent studies have focused on placental MDR1 expression, but few studies have analyzed placental MDR1 transport activity. The purpose of this study was to investigate placental MDR1 transport activity using a relatively large sample size of human placentas. Furthermore, the effect of ABCB1 gene polymorphisms were investigated along with physiological factors including maternal age, times of pregnancy, BMI, delivery mode or pregnancy complications on placental MDR1 transport activity.

METHODS

A total of 252 human placentas were obtained after delivery. MDR1 transport activity was detected by N-methyl quinidine uptake in placental microvillus membrane vesicles (MVMVs). Nine common single nucleotide polymorphisms (SNPs) in ABCB1 genes were determined by Snapshot. The association between ABCB1 gene polymorphisms, maternal age, times of pregnancy, BMI, delivery mode or pregnancy complications, and transporter activity was investigated.

RESULTS

Inter-individual variations of MDR1 transport activity were observed among 252 subjects. The per unit protein activity was ranged from 0.05 to 0.15/mg. Nine SNPs in ABCB1 gene didn't exhibit significant association with transporter activity of MDR1. Likewise, neither age, times of pregnancy, delivery mode nor pregnancy complications showed any significant effect of placental MDR1 transport activity. But placental MDR1 transport activity in obese pregnant women was lower than those in non-obese pregnant women.

CONCLUSION

Inter-individual variations of MDR1 transport activity existed in human placentas. This may contribute to variations in drug exposure to the fetus affecting clinical outcomes. Maternal age, times of pregnancy, delivery mode nor pregnancy complications included in this study maybe not significantly impact placental MDR1 transport activity, but maternal obese could inhibit placental MDR1 activity.

Drug transport across the human placenta: review of placenta-on-a-chip and previous approaches

In the past few decades, the placenta became a very controversial topic that has had many researchers and pharmacists discussing the significance of the effects of pharmaceutical drug intake and how it is a possible leading cause towards birth defects. The creation of an in vitro microengineered model of the placenta can be used to replicate the interactions between the mother and fetus, specifically pharmaceutical drug intake reactions. As the field of nanotechnology significantly continues growing, nanotechnology will become more apparent in the study of medicine and other scientific disciplines, specifically microengineering applications. This review is based on past and current research that compares the feasibility and testing of the placenta-on-a-chip microengineered model to the previous and underdeveloped in vivo and ex vivo approaches. The testing of the practicality and effectiveness of the in vitro, in vivo and ex vivo models requires the experimentation of prominent pharmaceutical drugs that most mothers consume during pregnancy. In this case, these drugs need to be studied and tested more often. However, there are challenges associated with the in vitro, in vivo and ex vivo processes when developing a practical placental model, which are discussed in further detail.