Hum. Reprod. Advance Access published online on August 6, 2008
Human Reproduction, doi:10.1093/humrep/den302
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First trimester embryo-fetoscopic and ultrasound-guided fetal blood sampling for ex vivo viral transduction of cultured human fetal mesenchymal stem cells
1 Experimental Fetal Medicine Group, Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0NN, UK 2 Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, London, UK 3 Experimental Fetal Medicine Group, Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, 5 Lower Kent Ridge Road, Singapore 119074, Singapore 4 Centre for Clinical Research, University of Queensland, Brisbane, Australia
5 Correspondence address. Experimental Fetal Medicine Group, Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, 5 Lower Kent Ridge Road, Singapore 119074, Singapore. Tel: +65-6772-2672; Fax: +65-6779-4753; E-mail: jerrychan{at}nus.edu.sg
BACKGROUND: Intrauterine stem cell transplantation is a promising approach for early onset genetic diseases. However, its utility is limited by the development of the fetal immune system after 14 weeks gestation. An ex vivo gene therapy approach targeting autologous first trimester stem cells to replace the missing or defective gene product should overcome this barrier. We investigated the feasibility of harvesting circulating first trimester human fetal mesenchymal stem cells (hfMSCs) for ex vivo gene therapy.
METHODS: Thin-gauge embryofetoscopic-directed or ultrasound-guided blood sampling (FBS) was performed in 18 pre-termination fetuses at a mean of 10+0 (range 7+2 to 13+4) weeks gestation through extra-fetal vessels. Harvested blood was plated for isolation of hfMSC and transduced by lentiviruses.
RESULTS: FBS was successful in 12/18 procedures (67%). Success rates were comparable in fetoscopic (4/6) and ultrasound-guided (8/12) procedures, but procedural time was shorter in the ultrasound-guided arm (P = 0.01). Fetal bradycardia occurred post-FBS in 33% and 25% of fetoscopic and ultrasound cases, respectively, 5 min post-procedure. hfMSCs were isolated in two-thirds of cases, with high efficiency lentiviral transduction achieved without affecting short-term cell renewal.
CONCLUSIONS: This phase-one study demonstrates the feasibility of the ex vivo fetal gene therapy approach, in which harvested hfMSCs are genetically manipulated prior to infusion back into the fetus where they should engraft and home to injured tissues. The fetal ex vivo gene therapy paradigm is also of relevance to haemopoietic stem cells to treat inherited haematological diseases. Optimization of stem cell harvest and longer-term safety is required before translation into clinical trials in ongoing pregnancies.
Key words: fetoscopy/percutaneous umbilical blood sampling/fetal blood sampling/mesenchymal stem cells/gene therapy
Submitted on April 8, 2008; resubmitted on June 1, 2008; accepted on June 4, 2008.