Transport and Biodistribution of Dendrimers Across Human Fetal Membranes: Implications for Intravaginal Administration of Dendrimers

Dendrimers are emerging as promising topical antimicrobial agents, and as targeted nanoscale drug delivery vehicles. Topical intravaginal antimicrobial agents are prescribed to treat the ascending genital infections in pregnant women. The fetal membranes separate the extra-amniotic space and fetus. The purpose of the study is to determine if the dendrimers can be selectively used for local intravaginal application to pregnant women without crossing the membranes into the fetus. In the present study, the transport and permeability of PAMAM (poly(amidoamine)) dendrimers, across human fetal membrane (using a side-by-side diffusion chamber), and its biodistribution (using immunofluorescence) are evaluated ex-vivo. Transport across human fetal membranes (from the maternal side) was evaluated using Fluorescein (FITC), an established transplacental marker (positive control, size~ 400 Da) and fluorophore-tagged G4-PAMAM dendrimers (~ 16 kDa). The fluorophore-tagged G4-PAMAM dendrimers were synthesized and characterized using 1H NMR, MALDI TOF-MS and HPLC analysis. Transfer was measured across the intact fetal membrane (chorioamnion), and the separated chorion and amnion layers. Over a five hour period, the dendrimer transport across all the three membranes was less than < 3 %, whereas the transport of FITC was relatively fast with as much as 49% transport across the amnion. The permeability of FITC (7.9 × 10-7 cm2/s) through the chorioamnion was 7-fold higher than that of the dendrimer (5.8 × 10-8 cm2/ s). The biodistribution showed that the dendrimers were largely present in interstitial spaces in the decidual stromal cells and the chorionic trophoblast cells (in 2.5 to 4 h) and surprisingly, to a smaller extent internalized in nuclei of trophoblast cells and nuclei and cytoplasm of stromal cells. Passive © 2009 Elsevier Ltd. All rights reserved. *Corresponding author: Rangaramanujam M. Kannan, Department of Chemical Engineering and Material Science, Wayne State University, Detroit, Michigan 48202; rkannan@eng.wayne. edu. aThese authors contributed equally to this manuscript. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Appendix. Supplementary Data. 1H NMR analysis of the intermediates and histology images are included. NIH Public Access Author Manuscript Biomaterials. Author manuscript; available in PMC 2011 June 1. Published in final edited form as: Biomaterials. 2010 June ; 31(18): 5007–5021. doi:10.1016/j.biomaterials. 2010.02. 075. N IH PA Athor M anscript N IH PA Athor M anscript N IH PA Athor M anscript diffusion and paracellular transport appear to be the major route for dendrimer transport. The overall findings further suggest that entry of drugs conjugated to dendrimers would be restricted across the human fetal membranes when administered topically by intravaginal route, suggesting new ways of selectively delivering therapeutics to the mother without affecting the fetus.