Fetal Stem Cell Therapy Ready for use

©CBreymann
Fetal Stem Cell Therapy
Ready for use ?
Prof. Dr. Christian Breymann
University Hospital Zurich
Dept. OBGYN and Obstetric Research
Congenital Amaurosis
©CBreymann
Time Mag, 2009
Time Mag, 2009
Perinatal SCT
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Fetus as recipient
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Current experience
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How to improve success ?
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Fetal and Postnatal Gene Therapy
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Safety & Ethical aspects
©CBreymann
Fetus as recipient
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Prenatal diagnostics is mandatory
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Invasive (CVS) , maternal blood (fetal DNA)
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Chromosomal defects, single gene disorders
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Karyotyping and molecular biology techniques
(PCR)
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Abnormal karyotype not from maternal blood !!
New: DNA chip technology (snips,
duplications…)
©CBreymann
the early gestational fetus (<12 week) is
Fetal tolerance immunologically naive
•
for alloantigen
Avoid early
onset organ
damage
• May allow targeting of otherwise inaccessible
organs and tissues
May allow permanent repair by cell replacement through
engraftment or induce tolerance for the transplant
•
Outcome
With permission from:
The-Hung Bui, MD The Karolinska Institute
Early gestation, an
highly proliferative
environment
•Large scale
migration of stem
cells to seed
anatomic
compartments for
tissue
differentiation
• Exponential
expansion of
cellular
compartments
With permission from:
The-Hung Bui, MD The Karolinska Institute
Large amounts of
stem cell can be
• fetus
< 75 g
given
before week 13
IUT,
a recapitulation of
ontogeny
•Engraftment,
migration,
expansion of
transplanted
cells, and
differentiation

Non-myeloablative strategy
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Prenatal tolerance induction to
facilitate postnatal
transplantation
Near complete or complete
donor chimerism

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Large number of target
disorders
Minimally invasive
procedure
With permission from:
The-Hung Bui, MD The Karolinska Institute

Fetal liver from early
gestations
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Hematopoietic SC
T-cells depleted adult
bone marrow
MSCs from fetal liver
or adult BM
But !.............
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Limited success of treatment in children !!
Promising results in 1/3 after allogeneic SCT
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Irreversible damage at birth frequent
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HLA compatibility
Immunosupression (recipient)
GvHD
Graft failure
Storage disease, Thallassemia, Osteogenesis
imperfecta
Diagnose and treat early >>
ameliorate long term health
©CBreymann
Prenatal Transplantation =
window of opportunity…..

1-2 Trimester

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Ontogenetic properties of haematopoietic
system
Immunological incompetence until 2. Tm

Across HLA barrirs
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No immunosupression,GvHD
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Stable engraftment and chimerism
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Prevention of full organ damage
©CBreymann
With permission from:
The-Hung Bui, MD The Karolinska Institute
Current Experience……
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> 30 experimental PST (Flake 1996)
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Mostly no clinical benefit
Pirovano 2004 >> improve immune system (T
cells)
Hb pathies, storage disease >> no sign.
Engraftment (Sanna 1999, Bambach 1997)
Window of opportunity only until 12 wog ?
Immunological barriers ?
 Host defense ?
 NK cells ?
 Competition of host hematopoeitic cells ?
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©CBreymann
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success in only a few fetuses
all with immunodeficiency disorders
bare lymphocyte syndrome
 SCID
 Omenn syndrome

Touraine et al. 1989, 1992; Flake et al. 1996;
Wangler et al. 1996; Lanfranchi et al. 1998;
Porta et al. 2000; Westgren et al. 2002; Porta
et al. 2002
With permission from:
The-Hung Bui, MD The Karolinska Institute
With permission from:
The-Hung Bui, MD The Karolinska Institute
Buckley NEJM 2000
With permission from:
The-Hung Bui, MD The Karolinska Institute
Buckley et al NEJM 1999
Fanos & Puck A J Med Genet 2001
How to improve ?

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Selective advantage of donor cells
Animal models (in utero transplantation):
 Modification of source and dose
 Route of administration (extracoelomic..)
 Cotransplantation of mesenchymal SC (MSC)
 Induction of microchimerism (in utero) for postnatal
transplantation
 Graft modulation of T cells
 Supression of fetal haematopoiesis (parvovirus B19)
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>> high – level engraftments in animal models
©CBreymann
Immunoglobulin
• ATG
• Anti-NK
Immunosuppression
• Corticosteroids
• Parvovirus
B19
Chemotherapy
• Cyclosporin
• FK-506
• MMF
Co-transplantation
with MSC
Macaque Fetus
With permission from:
The-Hung Bui, MD The Karolinska Institute
MSC (Mesenchymal stem cells)
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Reconstitute different tissues after in utero
transplantation
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Bone and cartilage (>> OI)
Improve engraftment if cotransplanted
Improve GvHD after HSCT
Less immunogenic >> later stage T possible
Le Blanc 2005 (OI), 5% donor cell chimerism
 Open influence on clinical course
 Potential in Bone, connective tissue, skeletal
(MDD), neurodegenration diseases
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©CBreymann
Götherström et al 2003, 2004, 2008; Lindton et al 2003; Le Blanc et al 2003;
Rasmusson et al 2003
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29 weeks GA. Fetus
with multiple femur,
tibia and rib
fractures
(osteogenesis
imperfecta type III)
CS at 36 weeks GA
Le Blanc et al. Transplantation 2005; 79:1607-14
With permission from:
The-Hung Bui, MD The Karolinska Institute

Engraftment 40-50/1000 of osteoblasts XY
Microchimerism
21 Trials completed
80 trials ongoin
5344 patients
42 trials autogenic
(1959 patients)
Fetal (autologous) gene therapy
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Excludes allogeneic HLA barriers
Improve of transduction of SC and expression of
therapeutic gene
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New vectors and transduction protocols
Prenatal induction of long term transgene tolerance
Lentiviral (HIV) based vectors
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Enhances efficiency and duration of gene expression (Zanjani
1999)
Efficient transduction in non dividing haematopoietic cells
superior to murine retroviruses
Long term expression of therapeutic b-globin in thlassemia
©CBreyman
Time Mag, 2009
Prenatal gene therapy
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In utero gene transfer models for
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Pulmonary epithelial cells, hepatocytes, skin, intestine, heart…….
(adenovirus, murine retroviral vectors)
Amniotic, tracheal, peritoneal, hepatc, vascular, placental
transfer of vector gene construct
Proof of principle for tolerance and gene expression after in
utero transfer in mouse/ rat
New approach: harvest of placental cells and retransfer after
gene transfer to placenta (Portmann-Lanz 2006)
Ex vivo gene therapy with haematopoietic stem cells
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HSC are reinduced after in vitro gene transfer
In vivo gene transfer
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Gene containing vector is transfered to fetus
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Positive results in murine thalassemia model (May 2000)
©CBreymann
Safety aspects…….
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Transduction of gonadal cells > genetic germ line
transduction
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Risk for fetus and mother (placental migration)
Insertional mutagenesis
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Functional gene defect, genetic disease
Malignant tumour (e.g. leukemia like syndrome, liver
tumours)
Ex vivo transfer maybe safer
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Mutagenesis detected before insertion…
Risk can not be completely ruled out
Ethics:
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Step from animal model to human gene transfer
Risk vs benefit (germ line transduction vs health of individual ) ?
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In utero gene therapy and stem cell
transplantation are still in their infancy
Much progress is being made in stem cell
biology and vector technology
In utero transplantations for SCIDs is a clinical
reality and potential for new indications using
MSCs and other stem cells
Proceed with caution, ethical issues have to be
addressed
With permission from:
The-Hung Bui, MD The Karolinska Institute
Prenatal/ fetal stem cell
therapy……is promising…..
……but not ready to take off
yet……
(advantages, safety, risks……)