Transplantation of hematopoietic stem cells in utero

Abstract

Hematopoietic stem cell (HSC) transplantation in children and adults with congenital lymphohematopoietic disorders is limited by donor availability, graft failure, graft-versus-host disease (GVHD) and delayed immunological reconstitution. These problems may be circumvented by transplanting the patient before birth. Prenatal cellular therapy for the treatment of congenital diseases has tremendous theoretical appeal. Potential advantages of prenatal transplantation include: A) fetal immunologic immaturity and the potential for induction of donorspecific tolerance; B) available space in the developing bone marrow for engraftment of donor cells; C) the sterile, protective, fetal environment which provides isolation from environmental pathogens, and D) prevention of clinical manifestations of the disease. Normal hematopoietic and immunologic development during ontogeny creates a "window of opportunity" during which events favor the engraftment of transplanted allogeneic (and xenogeneic) HSC and their proliferation. This is a period in which the fetus is immunologically naive and thus incapable of rejecting the foreign HSC, and the expanding bone marrow spaces allow homing and engraftment of HSC without the need for myeloablation. Experiments in sheep have established the optimal age of the recipient, route of donor cell administration, sources of HSC, and other parameters necessary for the successful engraftment and long-term expression of donor HSC. In preclinical studies, transplantation of CD34-enriched or highly purified populations of human adult bone marrow cells in utero resulted in the long-term engraftment and expression of donor HSC without graft failure and GVHD. The strategies developed in allogeneic and xenogeneic fetal sheep models were used to successfully treat human fetuses with X-linked recessive severe combined immunodeficiency. Stem Cells 1997;15(suppl1):79-93The engraftment and proliferation of a relatively small number of normal hematopoietic stem cells (HSC) can sustain hematopoiesis for a lifetime. This observation provides the compelling rationale for HSC transplantation (HSC-T) and is now supported by thousands of long-term survivors of HSC-T who would otherwise have succumbed to lethal disease. However, the realization of the full potential of HSC-T continues to be limited by a critical shortage of immunologically compatible donors, the inability to specifically control the recipient or donor immune response and the requirement for recipient myeloablation to achieve engraftment [ 1-41, The combination of graft failure, delayed immunologic reconstitution, graft-versus-host-disease (GVHD), and the relatively high morbidity and mortality associated with allogeneic HSC-T present prohibitive problems for the majority of patients who might benefit from this procedure. Fortunately, a number of innovative approaches offer hope for the future. These include Hematopoietic Stem Cells. STEM CELLS 1997;15(suppl 1):79-93 0 1997 AlphaMed Press. All rights reserved. 80In Utero HSC Transplantatio...

Improved transduction of human sheep repopulating cells by retrovirus vectors pseudotyped with feline leukemia virus type C or RD114 envelopes

“…53,54 Transduced CD34 ϩ cells and bone marrow cells from repopulated sheep were plated in MethoCult GF H4435 (StemCell Technologies, Vancouver, BC, Canada) and cultured at 37°C and 5% CO 2 according to the manufacturer's instructions. Individual culture colony-forming units (CFU-Cs) in 20 L medium were withdrawn with a Pipetman into 1 mL PBS (GIBCO).…”

“…The fetal sheep model was chosen for evaluating the engraftment of the most primitive human hematopoietic cells. 53,54 Cotransduced cells representing 9 independent peripheral blood CD34 ϩ -cell collections were transplanted into fetal sheep (5 FeLV-C/ GaLV, 4 RD114/GaLV, including 1 set of twins). DNA was extracted from peripheral blood and bone marrow cells collected from live-born animals between 1 to 9 months after birth for analysis of human hematopoietic-cell engraftment by PCR analysis †Determined by RT-PCR (n ϭ 6).…”

C1qRpdefines a new human stem cell population with hematopoietic and hepatic potential

“…However, the relationship between human CD34 Ϫ and CD34 ϩ stem cells and the role of CD34 Ϫ stem cells in clinical transplantation remain unclear. Xenograft repopulation assays using fetal sheep (7,8) and immune-deficient mice (9,10) were crucial for the identification of human CD34 Ϫ stem cells because Lin Ϫ CD34 Ϫ cells have little or no clonogenic [colony-forming cells (CFC)] or long-term culture-initiating cell (LTC-IC) activity. Using the sheep xenograft model, Zanjani et al showed that Lin Ϫ CD34 Ϫ cells contained stem cells capable of long-term repopulation and multilineage differentiation in vivo (5).…”

Transplantation of a fetus with paternal Thy-1+CD34+cells for chronic granulomatous disease

“…9 During this time of rapid expansion of hematopoiesis, donor HSCs might engraft without the need for cytoablative conditioning to provide space for the transplanted HSCs. These hypotheses have been supported by experiments in sheep and other large animals, 8 as well as successes in treating humans with immunodeficiency disorders using IUT. [10][11][12][13] The success of IUT in treating certain immunodeficiencies led us to explore this therapy for the treatment of chronic granulomatous disease (CGD).…”

“…[1][2][3][4] The proposed advantages of IUT pertain to the immaturity of the fetal immune system and the rapid development of the fetal hematopoietic system. 1,[5][6][7][8] Prior to 14 weeks gestation, the fetal immune system has been presumed to be immature and may allow transplantation of HSCs regardless of major histocompatibility antigen (MHC) disparity. Early in the second trimester, at the time of IUT, hematopoiesis is in a period of continued growth in the liver and colonization of the long bones has begun.…”