Attempted bone-marrow transplantation in a 17-week fetus

Stem Cell Transplantation in the Fetus

BACKGROUND

In utero transplantation (IUT) of hematopoietic stem cells has the potential to treat a large number of hematologic and metabolic diseases amenable to partial replacement of the hematopoietic system.

METHODS

A review of the literature was conducted that focused on the clinical and experimental experience with IUT and, in this context, the development of the hematopoietic and immune systems.

RESULTS

Successful application of IUT has been limited to the treatment of various types of immunodeficiencies that affect lymphocyte development and function. Other congenital defects such as the thalassemias have not resulted in clinically significant engraftment. Recent efforts at understanding and overcoming the barriers to engraftment in the fetus have focused on providing a selective advantage to donor stem cells and fostering immune tolerance toward the donor cells. The critical cellular components of the graft that promote engraftment and tolerance induction are being evaluated in animal models. Improvements in engraftment have resulted from the inclusion of T cells and/or dendritic cells in the graft, as well as a strategy of combined prenatal and postnatal transplantation.

CONCLUSIONS

The advantages, necessity, and benefits of early treatment will continue to encourage development of IUT as a means to treat hematopoietic and other types of birth defects.

Fetal stem-cell transplantation

Fetal stem-cell transplantation is an attractive approach to the treatment of a variety of hematological, metabolic and immunological diseases before birth. The possibility of delivering a large number of cells in an early stage of life, and of taking advantage of normal fetal stem-cell migration and development, is promising. During fetal life, the capacity to mount an immune response to allogeneic cells is impaired compared with adult life. This provides an opportunity to induce tolerance to alloantigens without the need for myeloablation, although there are possible immune barriers to foreign cells in the fetus.

In utero transplantation: baby steps towards an effective therapy

In utero transplantation (IUT) offers the potential to treat a large number of diseases by transplantation of healthy cells into a fetus with a birth defect. Prenatal diagnosis is feasible for many diseases prior to the full development of the fetal immune system offering the opportunity to introduce foreign cells and antigens into the developing fetus. At least 45 cases of IUT have been performed for a variety of diseases. IUT has successfully treated severe combined immunodeficiency and there are indications that it may be effective in treating some nonhematopoietic diseases. However, many diseases remain resistant to fetal therapy owing to the low levels of chimerism that can be achieved. Promising efforts to improve the levels of engraftment are focusing on optimizing the graft and developing donor-specific tolerance in the fetal recipient. Mounting evidence suggests that donor T cells can aid in achieving clinically significant levels of chimerism. The use of fetal donor cells may also offer some benefit. Animal experiments suggest that even low-level chimerism can lead to tolerance, which can be exploited by booster transplants in the neonate. Continued research appears likely to succeed in developing IUT into an effective form of therapy for a variety of diseases.

Cell-based therapies for birth defects: a role for adult stem cell plasticity?

Cell therapy can offer a reasonable approach to the treatment of specific birth defects, particularly those for which hematopoietic stem cells (HSCs) can be used to restore (even partially) the number of cells, protein levels, or enzyme activity. Relatively few clinical experiences have been published on this subject, but when a natural selective advantage exists for the cell graft, a degree of "rescue" is possible. Strategies have been developed to confer a selective advantage through genetic engineering of donor cells, and this approach may prove valuable in the treatment of birth defects, as it is in hematological malignancy. Stem cell (SC) plasticity, or transdifferentiation, may offer another route for delivery of cells to established or developing organs. A wide variety of studies support the concept that adult tissue-specific SCs can, if displaced from their normal niche to another, be reprogrammed to produce cell types appropriate to their new environment. Clinical observations reveal that persistent tissue microchimerism develops not only in blood lineages after transfusion, but also in thyroid follicular epithelium via transplacental exchange. In addition, hepatic and renal parenchyma also become chimeric following allografts or bone marrow transplantation (BMT). Experimental models indicate that a renal glomerulosclerosis phenotype can be transferred by grafting whole BM, and that a severe liver disorder in fah-/- mice can be overcome by grafting HSCs and then exerting a selection pressure. It may be possible in the future to exploit the ability of adult SCs to contribute to diverse tissues; however, our understanding of the processes involved is at a very early stage.

Fetal hematopoietic stem cell transplantation: a challenge for the twenty-first century

Successful in utero hematopoietic stem cell transplantation will likely represent a major step forward in the management of patients with congenital hematological, metabolic, and immunological disorders. We review the naturally occurring models of hematopoietic chimerism in animals and humans, as well as available experimental animal data and human clinical attempts of fetal transplantation. Data available from naturally occurring models and experimental models of fetal transplantation suggest that this technique should be translatable to the human fetus. However, to date, the success of human fetal hematopoietic stem cell therapy has been limited to fetuses with severe immunologic defects. Evaluation of successful attempts of human transplantation, the ontogeny of fetal immune development, and data available from animals provide insights into innovative approaches to fetal therapy that may bring the reality of successful fetal transplantation closer.

Stem cell therapy in utero

In utero stem cell transplantation represents a new and still experimental therapeutic strategy for diseases related to the hematopoietic system, i.e. hemoglobinopathies, immunodeficiency diseases and metabolic disorders. To date, a total of 21 cases of transplantations using stem cells either of fetal liver or adult bone marrow origin have been reported in the literature. Success has been limited--with the exception of one case of beta-thalassemia--to four cases with immunodeficiency diseases. In this review the broad therapeutic implications as well as potentials and limitations of this technique are summarized. Furthermore, ethical considerations based on the use of fetal cells are pointed out and a prospective view concerning experimental and clinical future perspectives including the possibility for gene therapy is presented.

Stem-cell transplantation for inherited immunodeficiency disorders

For patients with well-characterized, rapidly fatal, nonmalignant immunodeficiency disorders, such as SCID, the decision to proceed with allogeneic SCT is clear-cut. For patients with many other disorders, this decision can be extremely difficult. Disorders such as LAD or CGD have a variable natural history. Each patient must be considered individually, with the risk for SCT-related morbidity and mortality carefully weighed against that of the underlying disease. Significant advances during the past 10 years have made SCT a much safer procedure. Use of nonmyeloablative conditioning regimens as a means of reducing toxicity of high-dose chemotherapy and irradiation hold great promise. Highly immunosuppressive, nonchemotherapeutic agents that inhibit graft rejection or GVHD by blocking the critical costimulatory component of the T-cell receptor-antigen interaction are beginning to emerge and may be ideal for SCT of nonmalignant diseases. Therefore, the risk-benefit equation must be reassessed each year as the severity of patients' disorders is better defined and techniques of SCT improve.

Fetal target organs of graft-versus-host reaction induced in utero by injection of maternal cells in a pig model

The target organs of graft-versus-host reaction (GVHR) in adult or neonates are the site of multifocal lymphocytic infiltrates. GVHR can also be acquired in utero by maternal cells crossing the placenta, but the fetal target organs are unknown. The aim of this study was to determine these target fetal organs. The distribution pathway of infused labeled lymphocytes within cryostat sections of fetal organs was analyzed, and fetal target organs of infused lymphocytes were investigated in both isogenic and semiallogenic situations. Isogenic cells were observed in less organs and semiallogenic cells were localized in a more restricted number of organs than isogenic cells. Furthermore, the liver, the thyroid, and the spleen were the fetal target organs in the two studied gestations. GALT, thymus, and kidney were also lymphocyte targets in isogenic gestation. In conclusion, isogenic cells induced GVHR in more fetal organs than semiallogenic cells.

In utero hematopoietic stem cell transfer: current status and future strategies

Successful prenatal treatment of severe immunodeficiencies by allogeneic hematopoietic stem cell transplantation in utero has been reported. Though other diseases like hemoglobinopathies or storage diseases are potentially amenable to this novel therapeutic approach, no success has yet been achieved in recipients without severe immunodeficiency. Graft rejection by the developing fetus and/or lack of selective, competitive advantage of donor versus host stem cells preventing stable engraftment seem to be the major obstacles. Several strategies to overcome these hurdles are being explored in preclinical settings, including timing and repeated dosing of stem cell administration to the fetus, ex vivo modification of the transplant, using different fetal compartments as targets for early stem cell transfer, or inducing microchimerism for postnatal transplantation from the same donor. In addition, the exact definition of the basic concept of early fetal immunologic naivete and the understanding of the molecular basics of migration and homing in fetal hematopoiesis system seem mandatory for a successful approach. Gene therapy using ex vivo transduced autologous cord blood cells or direct gene targeting in utero are other potential means to correct hematopoietic and immunologic single gene disorders in utero, though this approach is still away from the stage of clinical trials.

Current status in intrauterine fetal stem cell therapy

In utero fetal stem cell transplantation, a today experimental treatment option, represents a new therapeutic strategy with broad implications for diseases related to the hematopoietic system. The object of the present paper is to give a review of the published literature on fetal stem cell therapy with special reference to immunological and strategical considerations. Furthermore, ethical considerations on account of the use of fetal cells are pointed out and a prospective view concerning experimental and clinical future perspectives is presented.

Tissue distribution of transplanted fetal liver cells in the human fetal recipient

OBJECTIVE

Our purpose was to study the tissue distribution and concentrations of transplanted fetal liver cells in the human fetus.

STUDY DESIGN

Radiolabeled indium 111 fetal liver cells were injected in vivo under ultrasonographic guidance into 10 normal fetuses (13 to 17 weeks of gestation) before a prostaglandin abortion. Six fetuses were injected intraperitoneally and four intracardially. Another two fetuses serving as controls were injected with indium-labeled maternal plasma. The fetuses were all alive, at least until 6 hours before expulsion. After expulsion the fetuses were dissected, and radioactivity was measured in various fetal tissues. Results for each tissue were expressed as percentages of the total injected dose.

RESULTS

Significantly greater uptake of fetal liver cells in the liver, spleen, thymus, kidney, lung, and placenta was obtained with intracardiac than with intraperitoneal injection. Skeletal uptake did not differ in relation to mode of administration. With intracardiac injection uptake was greater in such parenchymal organs as the liver, spleen, and thymus (4.9%, 4.0%, and 3.9%, respectively). Uptake in the rib, clavicle, humerus, and sternum was 2.7%, 1.8%, 2.1%, and 1.1%, respectively. Placental uptake was 0.1%. The intracardiac route yielded a higher concentration of cells in different fetal organs than did injection of only radiolabeled maternal plasma, suggesting an active uptake of cells in different fetal hematopoietic organs.

CONCLUSION

The mode of administration of fetal liver cells seems to be a major determinant of donor cell concentration in the transplanted human fetus and may be a significant determinant of the rate of successful engraftment.

Lack of evidence of permanent engraftment after in utero fetal stem cell transplantation in congenital hemoglobinopathies

The use of fetal hematopoietic stem cells for in utero transplantation to create permanent hematochimerism represents a new concept in fetal therapy. In one fetus with alpha-thalassemia, one with sickle cell anemia, and one with beta-thalassemia, we have transplanted fetal liver cells obtained from legal abortions in gestational weeks 6-11. The fetus with alpha-thalassemia was transplanted twice during pregnancy, in the 15th (20.4 x 10(8) cells/kg) and in the 31st weeks of gestation (1.2 x 10(8) cells/kg), and is now two years of age. One fetus with sickle cell anemia received its transplant in the 13th week of gestation (16.7 x 10(8) cells/kg), and is now one year old. The fetus with beta-thalassemia was transplanted in 18th week (8.6 x 10(8) cells/kg), and is now three months old. Engraftment was evaluated by chromosomal analysis (sex chromosomes), red cell phenotyping, HLA class I and II typing, and PCR (polymerase chain reaction) for Y chromosome-specific sequences and DNA polymorphisms in cord and peripheral blood. The children with alpha- and beta-thalassemia underwent bone marrow aspirations at 3 and 7 months of age, respectively. In neither of these cases were we able to detect convincing evidence of stem cell engraftment. Thus, the administration of fetal stem cells to fetal recipients after the 12th week of gestation did not result in permanent hematochimerism. It remains to be determined whether the engraftment process can be promoted by earlier transplantations and/or higher cell doses.

Quo vadis? Fetal tissue transplantation

The epidemiology and biologic characteristics of fetal tissue harvested from elective and spontaneous abortions are reviewed. The use of fetal bone marrow obtained from second trimester lost pregnancies is discussed. Allogeneic fetal tissue transplantation carried out in utero is reviewed. Data on intrauterine transplantation of human fetal bone marrow obtained from second trimester lost pregnancies into baboon fetuses are presented. The viability of this tissue, its clonogenic efficiency, engraftment, use in the future, and banking are discussed.

Stem cells from bone marrow, umbilical cord blood and peripheral blood for clinical application: current status and future application

Bone marrow transplantation (BMT) has progressed rapidly during the past two decades to that of a treatment of choice as a therapeutically effective modality for the treatment of selected patients with malignant disease and non-malignant hematological disorders. However, its use is limited by availability of human leukocyte antigens (HLA)-matched donor cells, engraftment and graft-versus-host disease (GVHD). Prevention of GVHD, improvement in the speed and quality of marrow reconstitution, and screening of new immunomodulating agents which improve engraftment and augment hemopoiesis are intense areas of investigation. To this end there has clearly been progress in purification and characterization of human stem cells from different tissue sources. Discussed in this review are: (a) stem cell purification, characterization and ex vivo expansion; (b) bone marrow stem cell transplantation; (c) cord blood stem cell transplantation; (d) peripheral blood stem cell transplantation; (e) fetal liver stem cell transplantation; (f) in utero stem cell transplantation; and (g) evaluation of the capacity of stem cells to serve as targets for gene therapy.

Transfusion-associated graft-versus-host disease and its prevention

Transfusion-associated graft-versus-host disease is a rare but usually fatal complication of transfusion of cellular blood components, caused by multiorgan engraftment and proliferation of donor T lymphocytes. The classical features of skin rash, diarrhoea and hepatitis, along with striking bone-marrow failure, are seen 1-2 weeks after transfusion. Although early reports described the condition only in immunosuppressed individuals, sharing of an HLA haplotype between donor and an immunocompetent recipient can also result in transfusion-associated graft-versus-host disease. The condition is entirely preventable by gamma irradiation of cellular blood components to 25 Gy, although this results in some reduction of red-cell viability and increased loss of red-cell potassium. The major indications for irradiated blood components include bone marrow/stem cell auto- or allografting, Hodgkin's disease, intrauterine transfusions, and transfusions from relatives or HLA-selected platelet donors.

Medical fetal therapy

Medical fetal therapy describes any therapy in which a pharmacological agent is administered to a woman or her fetus in order to avoid or alleviate fetal disease. Treatment of the fetus with blood products or injection of other agents can also be considered to be medical fetal therapy. This chapter reviewed the application of medical fetal therapy to the prevention of NTDs, treatment of endocrinological and metabolic disorders, such as CAH, thyroid disease and others, and the medical management of cardiac arrhythmias. Several haematological disorders and reviews of recent advances in genetic manipulation involving the use of stem-cell implantation were discussed. The field of medical fetal therapy has been extremely exciting and continues to evolve at a rapid pace. No doubt, future advances involving genetic manipulation or the use of molecular genetic techniques for diagnosis will continue to keep this field at the forefront of treatment and prevention of fetal disorders.

Transplantation of fetal cells

Cellular transplantation is an attractive alternative to whole-organ transplantation when only a discrete function of the organ is deficient. Early fetal donor cells have an advantage because they engraft readily and do not cause graft-versus-host disease. Similarly, the fetus is an ideal recipient of allogeneic fetal cells as it is incapable of rejecting them early in gestation. This review presents the theoretical rationale, recent research advances, and clinical implications for adults with diabetes mellitus and Parkinson's disease; we also describe in utero transplantation of fetal hematopoietic stem cells and hepatocytes for the treatment of inherited hematologic and hepatic deficiencies, as well as the use of fetal islet cells and dopamine-producing cells to treat postnatal conditions.

In utero transplantation of hematopoietic stem cells in sheep: the role of T cells in engraftment and graft-versus-host disease

Transplantation of hematopoietic stem cells (HSC) from adult sheep into fetal lambs results in hematopoietic chimerism and graft-versus-host disease (GVHD). To evaluate the role of T cells in HSC engraftment and GVHD we depleted adult marrow HSC of T cells and observed the incidence of chimerism and GVHD in the fetal recipients. Using a naturally occurring polymorphism of the beta-globin locus to detect engraftment, bone marrow obtained from homozygous type A hemoglobin adult sheep were transplanted (2 x 10(9) cells/kg fetal weight) into 90 days' gestation fetal lambs homozygous for type B hemoglobin. Donor HSC were T-cell depleted by treatment with antisera (raised in rabbits against sheep thymocytes) in the presence of complement. T-cell depletion resulted in significant decrease in hematopoietic colony formation by donor HSC in vitro (305 +/- 49 v 134 +/- 21 colonies/10(5) cells) that normalized by the addition of autologous T cells (433 +/- 32 colonies/10(5) cells). Marrow depleted of T cells exhibited reduced engraftment in the recipient fetuses. When T cells were added back to donor HSC (depleted of T cells) at near-normal concentrations, engraftment improved but the lambs also developed GVHD. The addition of T cells to donor HSC (depleted of T cells) at concentrations below that present in unprocessed bone marrow resulted in significant engraftment but not GVHD. T cells play an important role in both the engraftment of adult HSC in fetal recipients and the development of GVHD in chimeric newborns. The elimination of T cells prevents GVHD but markedly reduces engraftment.(ABSTRACT TRUNCATED AT 250 WORDS)

On the feasibility of inducing tolerance in man: a study in the cynomolgus monkey

Our previous work on the in vitro generation of cytotoxic T lymphocytes from the blood of 15-22-week-old fetuses, and on the induction of immunological tolerane in both radiation chimeras and neonatal mice, using T lymphocyte-depleted allogeneic bone marrow cells, has led us to believe that it should be possible to establish red cell chimerism in human fetuses by the infusion of allogeneic adult bone marrow cells. The essential prerequisite appears to be the removal of immunocompetent T lymphocytes from the bone marrow transplant, for new T cells generated from donor stem cells become tolerant to the histocompatibility antigens of the host's thymus and cannot, therefore, cause graft-versus-host disease (GVHD). Such an approach could be used in the treatment of fetuses diagnosed at an early stage as suffering from life-threatening inherited blood disorders. The experiments described here were designed to test this hypothesis in a sub-human primate species, Macaca fascicularis. Twenty-two cynomolgus monkeys received infusions of haploidentical (paternal) bone marrow between days 51 and 95 of gestation. There was no evidence of chimerism in animals inoculated after day 75 from mating. Eight out of 14 fetuses inoculated before day 70 were late intra-uterine deaths, four were hydropic and in one, histological confirmation of GVHD was obtained, indicating that tolerance can be induced at this time, as GVHD can occur only if donor cells survive. The T cell-depletion technique used here did not appear to prevent GVHD.