Enhancement by dimethyl myleran of donor type chimerism in murine recipients of bone marrow allografts

A major problem in using murine models for studies of bone marrow allograft rejection in leukemia patients is the narrow margin in which graft rejection can be analyzed. In mice irradiated with greater than 9 Gy total body irradiation (TBI) rejection is minimal, whereas after administration of 8 Gy TBI, which spares a significant number of clonable T cells, a substantial frequency of host stem cells can also be detected. In current murine models, unlike in humans, bone marrow allograft rejection is generally associated with full autologous hematopoietic reconstitution. In the present study, we investigated the effect of the myeloablative drug dimethyl myleran (DMM) on chimerism status following transplantation of T cell-depleted allogenic bone marrow (using C57BL/6 donors and C3H/HeJ recipients, conditioned with 8 Gy TBI). Donor type chimerism 1 to 2 months post-transplant of 1 to 3 x 10(6) bone marrow cells was markedly enhanced by using DMM one day after TBI and prior to transplantation. Conditioning with cyclophosphamide instead of DMM, in combination with 8 Gy TBI, did not enhance engraftment of donor type cells. Artificial reconstitution of T cells, after conditioning with TBI plus DMM, by adding mature thymocytes, or presensitization with irradiated donor type spleen cells 1 week before TBI and DMM, led to strong graft rejection and consequently to severe anemia. The anti-donor responses in these models were proportional to the number of added T cells and to the number of cells used for presensitization, and they could be neutralized by increasing the bone marrow inoculum. These results demonstrate the potential of DMM to facilitate engraftment in unsensitized mice in which the host stem cells may compete with donor type cells; the use of DMM to create models in which mechanisms of immune rejection can be studied without interference due to stem cell competition; and that bone marrow allograft rejection may be overcome by increasing the bone marrow inoculum in these stringent models.     

Syngeneic bone marrow transplantation reduces the hearing loss associated with murine mucopolysaccharidosis type VII

MPS VII mice are deficient in beta-glucuronidase and share many clinical, biochemical, and pathologic characteristics with human mucopolysaccharidosis type VII (MPS VII). We have shown that syngeneic bone marrow transplantation (BMT) prolongs survival and reduces lysosomal storage in many organs of the MPS VII mouse. In this report, we quantify the hearing loss and determine the impact of syngeneic BMT on the development of deafness and the associated pathology in the MPS VII mouse. Eleven weeks after syngeneic BMT performed at birth, treated MPS VII mice had normal auditory-evoked brainstem responses (ABR), whereas untreated MPS VII mice had ABR thresholds 43 dB higher than normal. Treated MPS VII mice had beta-glucuronidase-positive cells in the temporal bone and in the subepithelial connective tissue of the external auditory canal. There was less thickening of the tympanic membrane and middle ear mucosa and decreased distortion of the ossicles and the cochlear bone. Although transplanted MPS VII mice had increased ABR thresholds by 33 weeks of age, four of the six had thresholds 12 to 32 dB lower than untreated mutants. These data indicate that syngeneic BMT in newborn MPS VII mice prevents early hearing loss and, in some animals, results in long-term improved auditory function.     

A rapid dot-blot assay to assess chimerism following sex-mismatched bone marrow transplantation

Mixed chimerism may occur more frequently than previously thought following allogeneic bone marrow transplantation and may have implications in terms of relapse, graft-versus-host disease and immune reconstitution. DNA analysis using single or multilocus polymorphic probes cannot reliably discriminate between donor and recipient cells below a level of 10%. We used probe pHY2.1, a cloned segment of tandemly repeated DNA (2000 copies) on the long arm of chromosome Y. A dot blot procedure allowed us to immobilize DNA directly from 50 microliter of peripheral blood or bone marrow. Cross-reactivity was eliminated by hybridization at conditions of extreme stringency (65 degrees C, 50% formamide). Mixing experiments detected male DNA at a level of 0.1% after 10 h exposure. Five patients were studied serially post-bone marrow transplantation. One patient showed mixed chimerism for 12 months, one had complete autologous recovery and the remaining three showed complete engraftment. All results were verified by standard karyotyping on bone marrow cells. This technique is a simple, rapid and sensitive assay for chimerism following sex mismatched bone marrow transplantation.     

Mixed chimerism of erythro- and megakaryopoiesis following allogeneic bone marrow transplantation

Until now, studies on mixed chimerism (MCh) after allogeneic bone marrow transplantation (BMT) have predominantly focused on the B- and T-lymphocyte population, but not on distinct myeloid cell lineages like nucleated erythroid precursors and megakaryocytes. To evaluate the lineage-restricted MCh more explicitly in 10 patients with chronic myelogenous leukemia (CML), a quantitative analysis was performed on bone marrow biopsies following a sex-mismatched host/donor constellation. Techniques included immunophenotyping (antiglycophorin C, CD61) for the identification of erythro- and megakaryopoiesis and a simultaneously conducted genotyping with x- and y-chromosome-specific DNA probes. Normal bone marrow and specimens taken before BMT served as controls. Contrasting a total gender-dependent sex-typing in the latter samples in the early and late posttransplant period (up to 586 days), 3-9% erythroid precursors and about 16% megakaryocytes revealed a host-type origin. This significantly higher number of host megakaryocytes is explained by their polyploidy generating an increased probability to detect positive signals at a certain section level of the corresponding biopsies. A striking conversion of MCh to a recipient cell type was found in leukemic relapse with a more than 90% host-derived erythroid and megakaryocytic cell population in 4 patients approximately 643 days after BMT.     

Increased life span and correction of metabolic defects in murine mucopolysaccharidosis type VII after syngeneic bone marrow transplantation

The gusmps/gusmps mouse has no beta-glucuronidase activity and develops murine mucopolysaccharidosis type VII (MPS VII). The clinical and pathologic abnormalities are similar to those found in humans with severe MPS VII. Mutant mice are dysmorphic, dwarfed, and have a shortened life span. Pathologic findings include widespread lysosomal storage. To determine whether bone marrow transplantation (BMT) corrects these abnormalities, genetically identical mutant animals were given syngeneic bone marrow transplants using cells from +/+ mice. Initial experiments showed that levels of beta-glucuronidase activity in recipient tissues correlated with the amount of radiation administered before BMT. Two groups of mice given BMT therapy were observed for periods of 1 and 2 years, respectively. These mice were evaluated using a combination of clinical, biochemical, histochemical, and pathologic analyses. Spleen, liver, cornea, and glomerular mesangial cells showed essentially complete correction at all radiation doses. Storage was partially corrected in meninges and perivascular cells in brain, and in renal tubular epithelial cells at the higher radiation doses. Life span in BMT-treated animals was increased approximately three-fold, approaching that seen in normal mice after BMT. These results support the position that BMT has a place in the therapeutic regimen for MPS VII.     

Chromosomal transformation in donor cells following allogeneic bone marrow transplantation

We report here a monosomy 7 transformation of donor cells following matched-unrelated, same sex, allogeneic bone marrow transplantation in a patient with severe congenital aplastic anemia. A PCR technique was employed to amplify microsatellite markers on chromosome 7 to confirm donor/recipient identity. We found that the transformation of monosomy 7 occurred in previously genetically normal donor cells. This study suggests that the microenvironment of the bone marrow of our patient with severe congenital aplastic anemia may have played a critical role in the development of monosomy 7 of normal donor cells and we conclude that chromosomal microsatellite marker analysis can be a valuable tool for precise donor/recipient differentiation in engraftment monitoring.     

Development of tolerance to donor type and host type H-2 antigens following transplantation of allogeneic bone marrow in mice

The responsiveness in mixed lymphocyte culture (MLC) against donor, host or third party antigens both in the thymus and in the spleen was studied in allogeneic chimeras at different time intervals post-bone marrow transplantation (BMT), and the results were correlated with the development of host and donor-type cells in the thymus. Three significant findings were revealed by this analysis. (1) Low but significant anti-host responses are present in allogeneic chimeras despite the lack of graft-versus-host disease. The anti-host responses in MLC can initially be detected in the thymus during the first 3 weeks post-transplant. A significant anti-host response can subsequently be detected in the spleen during the second month post-BMT. (2) The MLC anti-host responses are always higher than the anti-donor responses, indicating that new bone marrow-derived cells which arrive in the thymus after BMT may have a more important role in tolerance induction than the thymus epithelium, which is of host origin and cannot be involved in clonal deletion of donor anti-donor responses. (3) A substantial number of residual host-type prothymocytes survives 9.0 Gy total body irradiation, as manifested by their progeny in the thymus, and reaches a maximum number of 26.6 x 10(6) cells on day 15 post-BMT, before being gradually replaced in the thymus by donor-type thymocytes. The host-type thymocytes are tolerant in MLC towards donor-type cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative analysis of mixed chimerism following allogeneic bone marrow transplantation using telomere flow-FISH

Assessment of mixed chimerism is of particular interest for allogeneic bone marrow or peripheral blood stem cell transplantation with reduced-intensity conditioning in order to study contribution of donor-type and host-type lymphohematopoiesis. Because the length of telomere repeat sequences is frequently shorter in leukemic compared to normal hematopoietic cells, this telomere repeat polymorphism might be a useful marker to analyze mixed chimerism in selected patients with short telomeres. Recently, fluorescence in situ hybridization and flow cytometry (flow-FISH) have been shown to be valuable tools to analyze the mean telomere length in hematopoietic cells. Here, we demonstrate in a case study on a patient with chronic lymphocytic leukemia (CLL) that telomere flow-FISH can in principle be exploited to quantitate the amount of donor- and host-type cells for chimerism analysis based on distinct histogram distributions which reflect cell populations with different telomere length.     

Donor cell expansion is delayed following nonablative in utero transplantation to treat murine mucopolysaccharidosis type VII

To block development of progressive childhood diseases, in utero transplantation (IUTx) requires immediate and significant donor peripheral blood (PB) cell amplification. To date, negligible and nontherapeutic donor PB cell levels have been observed postnatally, except in patients with immunodeficiency diseases. Donor cell fate in utero still is not clear. Ease of identifying and quantifying beta-glucuronidase (GUSB)-expressing donor cells in GUSB-null mucopolysaccharidosis type VII (MPSVII) mouse recipients allowed us to evaluate temporal donor cell engraftment and amplification post-IUTx. Like humans, MPSVII mice are unable to catabolize lysosomal glycosaminoglycans and progressively develop severe storage disease unless they are treated early in life.IUTx recipients were nonablated MPSVII fetuses and genetically stem cell-deficient, and hence myeloablated, W(41)/W(41) MPSVII fetuses. Donor GUSB+ cells were identified and counted in histochemical tissue sections. Quantitative results were confirmed by flow cytometry, enzyme analysis, and histopathology.Whereas GUSB+ cells engraft in most tissues in utero, significant amplification does not occur until the first postnatal week in the nonablated MPSVII hosts. In contrast, genetically myeloablated MPSVII recipients display widely distributed donor cell replacement accompanied by extensive amplification in utero. In both models, storage is alleviated in adult tissues with significant donor cell repopulation.To become therapeutic, IUTx must overcome the limitations of donor cell expansion in the highly competitive fetal environment. Fortunately, nonablative mechanisms to amplify cells in utero are coming on line.     

Hematopoietic donor chimerism and graft-versus-myeloma effect in relapse of multiple myeloma after allogeneic bone marrow transplantation

 A large group of patients relapsing after allogeneic bone marrow transplantation (BMT) have obtained remission after infusion of leukocytes from their original donor, suggesting a graft-versus-myeloma effect. However, side effects such as graft-versus-host disease and myelosuppression are severe, and sometimes fatal, complications of this therapeutic approach. Previously we demonstrated that patients with leukemia who lack donor hematopoiesis in relapse after BMT experience severe and lasting aplasia after infusion of donor leukocytes. In two patients – one with extramedullary and one with marrow relapse after a sex-mismatched transplantation – we analyzed hematopoietic chimerism by cell sorting and bone marrow cultures. CD34-positive cells, CD4-CD8-positive cells, committed progenitors, and LTC-IC were of donor origin, as demonstrated by two-color fluorescence in situ hybridization (FISH). Additionally, in relapse complete donor T-cell chimerism was seen. In contrast, plasma cells were of recipient origin in the patient who had a relapse in the bone marrow. Both patients were treated with infusions of donor leukocytes from their original donor. Neither patient suffered myelosuppression, and one achieved a stable complete remission. Received: February 26, 1999 / Accepted: April 14, 1999     

Effect of radiation dose on the development of mixed haemopoietic chimerism following T cell-depleted allogeneic bone marrow transplantation.

The presence of mixed haemopoietic chimerism (MXC) was evaluated by cytogenetic and molecular analysis in 48 patients undergoing T cell-depleted BMT. The dose of total body irradiation (TBI) prescribed to all patients (14.4 Gy) was calculated to compensate for the absence of T cells in the graft. The actual midline dose of TBI received, however, differed significantly depending on the method of TBI administration. Thus, 35 adult patients received an average midline dose of 14.3 Gy, while 13 children received a lower dose of 13 Gy. The incidence of MXC in the adult group, who had received very close to 14.4 Gy to the midline, was 34% (12/35), which is lower than in most reported T cell-depleted series. During follow-up, chimerism remained relatively stable with time but varied between haemopoietic lineages. There was no relationship with relapse. MXC in the 13 children who had received a lower midline TBI dose was significantly higher at 69% (9/13) (p < 0.05) and increased to 90% (9/10) if patients who received additional chemotherapy in their conditioning were excluded (p = 0.001). This suggests that, in terms of marrow ablation, relatively small changes in the dose of TBI may be biologically significant, at least at this dose range. Again, in the lower TBI group MXC was not predictive of relapse.     

Assessment and management of donor pain following marrow harvest for allogeneic bone marrow transplantation

We studied the time course and intensity of pain of multiple bone marrow aspirations in 30 healthy adult marrow donors receiving acetaminophen with codeine for analgesia immediately after marrow harvesting for allogeneic bone marrow transplantation. Upon discharge, donors were supplied with acetaminophen (315 mg) plus codeine (30 mg) tablets and instructed to use one or two tablets up to every 4 h as needed for pain control. Donors used analgesic medication for a mean (+/- SE) of 3.3 +/- 0.5 days (range = 1-13 days) and reported less than complete pain relief. Subjects reported more pain at time of medication than between doses, indicating that the analgesic was at least partially effective. Male donors tended to report more pain and use more analgesic than did females. We conclude that donors self-regulate their analgesic usage to achieve maximal relief and that incomplete relief with acetaminophen plus codeine may be due to limited efficacy of this analgesic preparation. Our findings suggest that donor pain management may be improved by use of more powerful analgesics.     

Increased longevity and metabolic correction following syngeneic BMT in a murine model of mucopolysaccharidosis type I

Mucopolysaccharidosis type I (MPS I) is an autosomal recessive inherited disease caused by deficiency of the glycosidase α-L-iduronidase (IDUA). Deficiency of IDUA leads to lysosomal accumulation of glycosaminoglycans (GAG) heparan and dermatan sulfate and associated multi-systemic disease, the most severe form of which is known as Hurler syndrome. Since 1981, the treatment of Hurler patients has often included allogeneic BMT from a matched donor. However, mouse models of the disease were not developed until 1997. To further characterize the MPS-I mouse model and to study the effectiveness of BMT in these animals, we engrafted a cohort (n=33) of 4-8-week-old Idua(-/-) animals with high levels (88.4±10.3%) of wild-type donor marrow. Engrafted animals displayed an increased lifespan, preserved cardiac function, partially restored IDUA activity in peripheral organs and decreased GAG accumulation in both peripheral organs and in the brain. However, levels of GAG and GM3 ganglioside in the brain remained elevated in comparison to unaffected animals. As these results are similar to those observed in Hurler patients following BMT, this murine-transplantation model can be used to evaluate the effects of novel, more effective methods of delivering IDUA to the brain as an adjunct to BMT.     

Transfer of autoimmune hypothyroidism following bone marrow transplantation from a donor with Graves' disease

We describe the transfer of a different autoimmune thyroid disorder by bone marrow transplantation. The donor had euthyroid Graves' disease after treatment with antithyroid drugs and stable oxopthalmos, with persistent thyroid autoantibodies. One year after bone marrow transplant, the recipient developed atrophic autoimmune hypothyroidism. Six months later the donor developed transient subclinical hypothyroidism followed by clinical hyperthyroidism. In both recipient and donor the presence of thyrotropin (TSH)-binding inhibitory immunoglobulins was documented. Although TSH receptor antibodies usually act as a TSH agonist causing thyrotoxicosis, they can also can act as a TSH antagonist causing primary hypothyroidism. This case may be an example of how the same antibody can act as an agonist in the donor and an antagonist in the bone marrow recipient, causing two different autoimmune disorders: primary hypothyroidism in the recipient and Graves' disease in the donor.     

Effects of mixed hematopoietic chimerism in a mouse model of bone marrow transplantation for sickle cell anemia

Sickle cell anemia (SCA) is an inherited disorder of beta-globin, resulting in red blood cell rigidity, anemia, painful crises, organ infarctions, and reduced life expectancy. Allogeneic blood or marrow transplantation (BMT) can cure SCA but is associated with an 8% to 10% mortality rate, primarily from complications of marrow-ablative conditioning. Transplantation of allogeneic marrow after less intensive conditioning reduces toxicity but may result in stable mixed hematopoietic chimerism. The few SCA patients who inadvertently developed mixed chimerism after BMT remain symptom free, suggesting that mixed chimerism can reduce disease-related morbidity. However, because the effects of various levels of mixed chimerism on organ pathology have not been characterized, this study examined the histologic effects of an increasing percentage of normal donor hematopoiesis in a mouse model of BMT for SCA. In lethally irradiated normal mice that were reconstituted with varying ratios of T-cell-depleted marrow from normal and transgenic "sickle cell" mice, normal myeloid chimerism in excess of 25% was associated with more than 90% normal hemoglobin (Hb). However, 70% normal myeloid chimerism was required to reverse the anemia. Organ pathology, including liver infarction, was present in mice with sickle Hb (HbS) levels as low as 16.8% (19.6% normal myeloid chimerism). Histologic abnormalities increased in severity up to 80% HbS, but were less severe in mice with more than 80% HbS than in those with 40% to 80% HbS. Therefore, stable mixed chimerism resulting from nonmyeloablative BMT may reduce the morbidity from SCA, but prevention of all disease complications may require minimizing the fraction of circulating sickle red cells. (Blood. 2001;97:3960-3965)     

Transduction of donor hematopoietic stem-progenitor cells with Fas ligand enhanced short-term engraftment in a murine model of allogeneic bone marrow transplantation

Fas-mediated apoptosis is a major physiologic mechanism by which activated T cells are eliminated after antigen-stimulated clonal expansion generates a specific cellular immune response. Because activated T cells are the major effectors of allograft rejection, we hypothesized that genetically modifying allogeneic bone marrow (BM) cells prior to transplantation could provide some protection from host T-cell attack, thus enhancing donor cell engraftment in bone marrow transplantation (BMT). We undertook studies to determine the outcome of lentiviral vector-mediated transduction of Fas ligand (FasL) into lineage antigen-negative (lin(-)) mouse BM cells (lin(-) BMs), in an allogeneic BMT model. FasL-modified lin(-) BMs killed Fas-expressing T cells in vitro. Mice that received transplants of allogeneic FasL(+) lin(-) BMs had enhanced short-term engraftment, after nonmyeloablative conditioning, as compared to controls. We observed no major hepatic toxicity or hematopoietic or immune impairment in recipient mice at these time points. These results suggest potential therapeutic approaches by manipulating lymphohematopoietic stem-progenitor cells to express FasL or other immune-modulating genes in the context of BMT.     

Reconstitution of T-cell receptor repertoire diversity following T-cell depleted allogeneic bone marrow transplantation is related to hematopoietic chimerism

CDR3 spectratyping was used to analyze the complexity of the T-cell repertoire and to define the mechanisms and kinetics of the reconstitution of T-cell immunity after allogeneic bone marrow transplantation (BMT). This method, which is based on polymerase chain reaction amplification of all CDR3 regions using the T-cell receptor (TCR) Vbeta genes, was used to examine serial samples of peripheral blood lymphocytes from 11 adult patients with chronic myelogenous leukemia (CML) who underwent T-cell-depleted allogeneic BMT. In contrast to 10 normal donors who display highly diverse and polyclonal spectratypes, patient samples before and early after BMT revealed markedly skewed repertoires, consisting of absent, monoclonal, or oligoclonal profiles for the majority of Vbeta subfamilies. To quantify changes in TCR repertoire over time, we established an 8-point scoring system for each Vbeta subfamily. The mean complexity score for patient samples before transplant (130.8) was significantly lower than that for normal donors (183; P = 0. 0007). TCR repertoire complexity was abnormal in all patients at 3 months after BMT (mean score = 87). Normalization of repertoire began in 4 patients at 6 months after BMT, but the majority of patients continued to display abnormal repertoires for up to 3 years after BMT. To determine whether the reconstituted T-cell repertoire was derived from the donor or recipient, unique microsatellite loci were examined to establish chimeric status. At 3 months after BMT, 7 patients demonstrated mixed chimerism; 4 had complete donor hematopoiesis (CDH). CDH strongly correlated with likelihood of restoration of T-cell repertoire complexity (P = 0.003). In contrast, patients who demonstrated persistence of recipient hematopoiesis failed to reconstitute a diverse TCR repertoire. These findings suggest that the reconstitution of a normal T-cell repertoire from T-cell progenitors in adults is influenced by interactions between recipient and donor hematopoietic cells. (Blood. 2000;95: 352-359)     

Early establishment of hematopoietic chimerism following allogeneic peripheral blood stem cell transplantation in comparison with allogeneic bone marrow transplantation

To characterize the process of the establishment of complete chimerism after allogeneic peripheral blood stem cell transplantation (allo-PBSCT), we determined the origin of leukocytes in peripheral blood (PB) obtained from 23 patients in the very early period after allo-PBSCT using amplification of mini- or microsatellite regions of genomic DNA. Donor-specific alleles were amplified from the PB obtained at day 8 post-transplant for 19 allo-PBSCT patients. Among the 19 patients, 12 showed only donor-specific alleles (complete chimerism) while 7 did both donor and host-specific alleles (mixed chimerism). Although donor specific alleles were amplified in 10 of 12 patients who received allogeneic bone marrow transplantation (allo-BMT) similarly to allo-PBSCT, all of these ten showed mixed chimerism. When the chimeric state was examined in PB samples obtained serially at 2-3-day intervals post-transplant, host-specific alleles in allo-PBSCT patients were not detectable in the PB much earlier than those in allo-BMT patients. These findings indicate that the appearance of donor-derived cells associated with the disappearance of host-derived cells in the circulation occurs earlier after allo-PBSCT as compared with allo-BMT, leading to the rapid establishment of complete chimerism.     

The use of short tandem repeat polymorphisms for monitoring chimerism following bone marrow transplantation: a short report

Following immunohaematopoietic stem cell transplantation, it is of importance to determine whether the new blood forming system is of recipient or donor origin and such phenotypic characterisation is called chimerism analysis. This is a dynamic process, which may be complete, mixed or split between compartments and in this way, plays an increasingly important role in predicting outcome for engraftment, rejection or residual disease predicating the need for pre-emptive immunotherapy. Based on recent workshop recommendations, peripheral blood cells have been used in the short tandem repeat (STR) assay to serially characterise the haematologic course and so evaluate the usefulness of this system. Forty-six patients from a single centre were followed serially for periods ranging between 3 and 60 months. The analysis was initially performed using the Applied Biosystems Profiler Plus Kit; currently, the Promega Powerplex 16 system is used. The overlap between the two assays has allowed for continuous comparison. The initial analysis was performed at 14 days post-transplant and repeated monthly. Stored DNA from the patient and donor was used to establish the pre-transplant profile. All post-transplant analyses were performed using peripheral blood. The results obtained were expressed as a percentage of the donor profile. To illustrate the ability of this technology, three representative profiles are described. In the first, stable engraftment is confirmed at 20 months with only donor pattern present. The second is intermediate, and while the patient is clinically disease free, there exists stable mixed chimerism at about 75% of donor cells. The third patient initially engrafted but the reappearance of recipient alleles presaged a haematological relapse; the latter is an indication for salvage with donor lymphocyte infusion and here this assay will be used to show the effectiveness of the intervention. These preliminary results show this to be a useful additional tool in monitoring post-transplant engraftment. As a basis for pro-active therapy, a larger study integrating the results of haematological and cytogenetic markers is planned.