A comparison of murine T-cell-depleted adult bone marrow and full-term fetal blood cells in hematopoietic engraftment and immune reconstitution

In vivo engineering of mobilized stem cell grafts with the immunomodulatory drug FTY720 for allogeneic transplantation

The immunological attributes of stem cell grafts play an important role in the outcome of allogeneic stem cell transplants. Currently, ex vivo manipulation techniques such as bulk T-cell depletion or positive selection of CD34(+) cells are utilized to improve the immunological attributes of grafts and minimize the potential for graft-versus-host disease (GvHD). Here, we demonstrate a novel graft engineering technique, which utilizes the immunomodulatory drug FTY720 for in vivo depletion of naïve T (TN ) cells from donor G-CSF-mobilized grafts without ex vivo manipulation. We show that treatment of donor mice with FTY720 during mobilization depletes grafts of TN cells and prevents lethal GvHD following transplantation in a major mismatch setting. Importantly, both stem cells and NK cells are retained in the FTY720-treated grafts. FTY720 treatment does not negatively affect the engraftment potential of stem cells as demonstrated in our congenic transplants or the functionality of NK cells. In addition, potentially useful memory T cells may be retained in the graft. These findings suggest that FTY720 may be used to optimize the immunological attributes of G-CSF-mobilized grafts by removing potentially deleterious TN cells which can contribute to GvHD, and by retaining useful cells which can promote immunity in the recipient.

Long-term in vivo imaging of multiple organs at the single cell level

Two-photon microscopy has enabled the study of individual cell behavior in live animals. Many organs and tissues cannot be studied, especially longitudinally, because they are located too deep, behind bony structures or too close to the lung and heart. Here we report a novel mouse model that allows long-term single cell imaging of many organs. A wide variety of live tissues were successfully engrafted in the pinna of the mouse ear. Many of these engrafted tissues maintained the normal tissue histology. Using the heart and thymus as models, we further demonstrated that the engrafted tissues functioned as would be expected. Combining two-photon microscopy with fluorescent tracers, we successfully visualized the engrafted tissues at the single cell level in live mice over several months. Four dimensional (three-dimensional (3D) plus time) information of individual cells was obtained from this imaging. This model makes long-term high resolution 4D imaging of multiple organs possible.

Molecular measurement of T cell receptor excision circles

This chapter provides protocols necessary for quantifying human, mouse, and nonhuman primate signal joint T cell receptor excision circles (sjTRECs) produced during T cell receptor alpha (TCRA) gene rearrangement. These non-replicated episomal circles of DNA are generated by the recombination process used to produce antigen-specific T cell receptors. The number of sjTRECs per mg of thymus tissue or per 100,000 lysed cells has been shown to be a molecular marker of thymopoiesis and naïve T cells. This technology is beneficial to investigators interested in quantitating the level of naïve T cell production occurring under various circumstances in a variety of systems, and complements traditional phenotypic analyses of thymopoiesis. This chapter specifically describes procedures required for rapid detection and quantitation of sjTRECs in thymus tissue or isolated cells using real-time quantitative polymerase chain reaction (PCR). The sjTREC assay system comprises species-specific forward and reverse primers for amplification of a unique site on the T cell receptor δ (TCRD) sjTREC, a fluorescently labeled (FAM/ZEN/IABkFQ) species-specific real-time probe, and a species-specific sjTREC DNA plasmid standard for quantitation.

Keratinocyte growth factor enhanced immune reconstitution in murine allogeneic umbilical cord blood cell transplant

Umbilical cord blood (UCB) is used increasingly as a source of hematopoietic cells because of a lower risk of graft-versus-host disease (GVHD). Myeloablative conditioning before allogeneic umbilical cord blood transplant (allo-UCBT) results in thymic epithelial cell injury and T-cell immune deficiency. Full-term fetal blood cells were used as hematopoietic cells in a previous murine allo-UCBT model with a limited number of mice surviving the myeloablative conditioning. We designed a viable murine allo-UCBT protocol with platelet concentrate support. Keratinocyte growth factor (KGF) is a mitogen of thymic epithelial cells that promotes recovery of thymic epithelium when given before total body irradiation (TBI)-containing conditioning in experimental murine models. We hypothesized that KGF pre-administration would improve post-allo-UCBT thymopoiesis. To test this hypothesis, allo-UCBT recipient mice were given KGF or control saline prior to UCBT. Platelet concentrate support significantly improved the survival rate of murine allo-UCBT recipients. KGF administration significantly increased donor-derived T and natural killer T (NKT) cells at day +35 in spleens of allo-UCBT recipients. KGF administration also improved thymic function after allo-UCBT, resulting in higher copies of signal joint T-cell receptor rearrangement excision circles (sjTRECs) in splenocytes. Finally, we found that KGF pre-administration could enhance the graft-versus-leukemia effect. In conclusion, KGF can be administered safely to recipients of allo-UCBT to enhance T-cell immune reconstitution.

Immune Reactions following Cord Blood Transplantations in Adults

Cord blood transplantation (CBT) is an attractive alternative therapy in adult patients with advanced hematological malignancies in whom matched donors are unavailable. However, the risk of complications, especially infections, post-CBT increases the mortality rates in these patients. Although the incidence of acute and chronic graft versus host disease (GVHD) post-CBT is lower than that following bone marrow transplantation and peripheral blood stem cell transplantation (SCT), the additional immunosuppressive therapy required to treat it could increase the mortality in these patients. Further, chronic GVHD following CBT is milder and responds better to treatment than that occurring after bone marrow transplants. Unlike bone marrow transplantation, the onset of GVHD is a positive prognostic indicator of overall survival in patients receiving CBT, due to the graft versus malignancy (GVM) effect. This paper focuses on the immune reactions following CBT and aims to elucidate a management strategy for acute and chronic GVHD.

Improved engraftment with minimal graft-versus-host disease after major histocompatibility complex-mismatched cord blood transplantation with photochemically treated donor lymphocytes

There is a significant risk of severe graft-versus-host disease (GVHD) and graft failure after unrelated umbilical cord blood transplantation (CBT) if donor-recipient pairs are mismatched at major histocompatibility complex (MHC) loci. To mitigate these risks after MHC-mismatched CBT, we infused psoralen-treated, photochemically inactivated, mature donor T-lymphocytes with MHC (H2-haplotype) mismatched murine donor fetal near-term peripheral blood (FNPB) cells after sublethal irradiation. We analyzed the rates of donor engraftment, GVHD and long-term survival in H2 haplotype disparate (C57BL/6 [H-2(b)/Thy1.1] → AKR [H-2(k)/Thy1.2]) recipient mice. We observed inconsistent donor engraftment after transplantation with cord blood alone, but superior engraftment and long-term survival after FNPB transplantation supplemented with psoralen-treated donor T-lymphocytes. Additionally, there was fatal GVHD after FNPB co-infusion with untreated donor T-lymphocytes, but minimal GVHD after FNPB supplemented with psoralen-treated donor T-lymphocytes transplantation. Donor MHC(high)/c-Kit(+)/lineage(-)/CD34(-) stem cells were noted in the recipient bone marrow compartment following co-infusion of photochemically inactivated T-cells with FNPB. Despite the non-myeloablative preparation before FNPB infusion, complete hematological recovery was delayed until 50-60 d after transplantation. We observed that co-transplantation of psoralen-treated donor T-lymphocytes with FNPB facilitated durable engraftment of donor hematopoietic stem cells in the marrow and splenic compartments with complete but delayed recovery of all hematopoietic lineages. This CBT model establishes the possibility of ensuring donor engraftment across a MHC barrier without severe GVHD.

Selective enhancement of donor hematopoietic cell engraftment by the CXCR4 antagonist AMD3100 in a mouse transplantation model

The interaction between stromal cell-derived factor-1 (SDF-1) with CXCR4 chemokine receptors plays an important role in hematopoiesis following hematopoietic stem cell transplantation. We examined the efficacy of post transplant administration of a specific CXCR4 antagonist (AMD3100) in improving animal survival and in enhancing donor hematopoietic cell engraftment using a congeneic mouse transplantation model. AMD3100 was administered subcutaneously at 5 mg/kg body weight 3 times a week beginning at day +2 post-transplant. Post-transplant administration of AMD3100 significantly improves animal survival. AMD3100 reduces pro-inflammatory cytokine/chemokine production. Furthermore, post transplant administration of AMD3100 selectively enhances donor cell engraftment and promotes recovery of all donor cell lineages (myeloid cells, T and B lymphocytes, erythrocytes and platelets). This enhancement results from a combined effect of increased marrow niche availability and greater cell division induced by AMD3100. Our studies shed new lights into the biological roles of SDF-1/CXCR4 interaction in hematopoietic stem cell engraftment following transplantation and in transplant-related mortality. Our results indicate that AMD3100 provides a novel approach for enhancing hematological recovery following transplantation, and will likely benefit patients undergoing transplantation.

Endothelial progenitor cell infusion induces hematopoietic stem cell reconstitution in vivo

Hematopoietic stem cells (HSCs) reside in association with bone marrow (BM) sinusoidal vessels in vivo, but the function of BM endothelial cells (ECs) in regulating hematopoiesis is unclear. We hypothesized that hematopoietic regeneration following injury is regulated by BM ECs. BALB/c mice were treated with total body irradiation (TBI) and then infused with C57Bl6-derived endothelial progenitor cells (EPCs) to augment endogenous BM EC activity. TBI caused pronounced disruption of the BM vasculature, BM hypocellularity, ablation of HSCs, and pancytopenia in control mice, whereas irradiated, EPC-treated mice displayed accelerated recovery of BM sinusoidal vessels, BM cellularity, peripheral blood white blood cells (WBCs), neutrophils, and platelets, and a 4.4-fold increase in BM HSCs. Systemic administration of anti-VE-cadherin antibody significantly delayed hematologic recovery in both EPC-treated mice and irradiated, non-EPC-treated mice compared with irradiated controls. These data demonstrate that allogeneic EPC infusions can augment hematopoiesis and suggest a relationship between BM microvascular recovery and hematopoietic reconstitution in vivo.

Chronic graft-versus-host disease following umbilical cord blood transplantation: retrospective survey involving 1072 patients in Japan

We have little information on chronic graft-versus-host disease (GVHD) after cord blood transplantation (CBT). We investigated its clinical features in 1072 Japanese patients with hematologic malignancies who received a transplant through the Japan Cord Blood Bank Network. The primary end point was to investigate the incidence of any chronic GVHD. Median age of the patients was 33 years (range, 0-79 years). The cumulative incidence of chronic GVHD 2 years after transplantation was 28%. Chronic GVHD was fatal in 29 patients. Multivariate analysis demonstrated that development of chronic GVHD was favorably associated with both overall survival and event-free survival. Multivariate analysis identified risk factors of chronic GVHD: higher patient body weight, higher number of mismatched antigens for GVHD direction, myeloablative preparative regimen, use of mycophenolate mofetil in GVHD prophylaxis, and development of grades II to IV acute GVHD. Although chronic GVHD is a significant problem after CBT, it is associated with improved survival, perhaps due to graft-versus-malignancy effects.

Clinical characteristics of chronic graft-versus-host disease following umbilical cord blood transplantation for adults

Chronic GVHD is a significant complication following allogeneic hematopoietic stem cell transplantation; however, the clinical characteristics of chronic GVHD following cord blood transplantation (CBT) in adults have not been well described. Between March 2001 and November 2005, a total of 77 patients underwent CBT at eight transplantation centers of the Nagoya Blood and Marrow Transplantation Group. Of 77 patients, 29 survived without graft failure or progression of underlying diseases for at least 100 days after transplantation. The median age of the 29 patients was 42 years (range, 18-67 years). Seven patients developed chronic GVHD (extensive, n=4; limited, n=3) disease. The cumulative incidence of chronic GVHD 1 year after day 100 was 24% (95% confidence interval (CI), 11-41%), and the organs involved were the skin (n=6), oral cavity (n=4), liver (n=1) and gastrointestinal tract (n=1). In three patients, chronic GVHD was resolved with supportive care. The remaining four were successfully treated with additional immunosuppressive therapy. Event-free survival rates of the 29 patients with and without chronic GVHD 3 years after day 100 were 83 (95% CI, 27-97%) and 36% (95% CI, 17-56%), respectively (P=0.047). These results suggest that chronic GVHD following CBT is mild and has a graft-versus-malignancy effect.

Fetal stem cells

Fetal stem cells can be isolated from fetal blood and bone marrow as well as from other fetal tissues, including liver and kidney. Fetal blood is a rich source of haemopoietic stem cells (HSC), which proliferate more rapidly than those in cord blood or adult bone marrow. First trimester fetal blood also contains a population of non-haemopoietic mesenchymal stem cells (MSC), which support haemopoiesis and can differentiate along multiple lineages. In terms of eventual downstream application, both fetal HSC and MSC have advantages over their adult counterparts, including better intrinsic homing and engraftment, greater multipotentiality and lower immunogenicity. Fetal stem cells are less ethically contentious than embryonic stem cells and their differentiation potential appears greater than adult stem cells. Fetal stem cells represent powerful tools for exploring many aspects of cell biology and hold considerable promise as therapeutic tools for cell transplantation and ex vivo gene therapy.

Measurement of mouse T cell receptor excision circles

This unit provides the protocols necessary for the quantification of mouse single joint T cell receptor excision circles (sjTRECs) generated during TCRA gene rearrangement. These nonreplicated episomal circles of DNA are generated by the recombination process used to produce antigen-specific T cell receptors. The number of sjTRECs per mg of thymus tissue or per 100,000 lysed cells has been shown to be a molecular marker of thymopoiesis and naïve T cells. This technology is beneficial to investigators interested in quantitating the level of thymopoiesis occurring in both in vivo and in vitro mouse systems and complements traditional phenotypic analyses of thymopoiesis. The for real-time PCR details the assay for use on a Bio-Rad iCycler iQ. An is provided for an ABI Prism 7700. In addition, the unit includes Support Protocols for preparation of a mouse sjTREC DNA standard () and preparation of mouse thymus tissue DNA () as well as a protocol for proteinase K lysis of lymphocytes () used in the Basic and Alternate protocols.

Hematopoietic stem cell dose correlates with the speed of immune reconstitution after stem cell transplantation

In the current study, we tested whether higher numbers of hematopoietic stem cells correlate with the speed of immune reconstitution in a congenic transplantation model (C57BL/Ka, CD45.1, Thy1.1→C57BL/6, CD45.2, Thy1.2) using purified hematopoietic stem cells (c-Kit+Thy1.1lowLin-/lowSca-1+). There were 3 different doses of stem cells used (400, 1000, and 5000). Phenotypic analyses in peripheral blood and spleen demonstrated that higher numbers of infused stem cells are associated with more rapid regeneration of T cells (CD4+, CD8+, naive CD4+, naive CD8+) and B cells at early time points. The numbers of T and B cells eventually became equivalent between different dose groups at late time points. Production of interleukin-2 and inter-feron-γ per T cell was similar regardless of stem cell dose even when tested at the time when there were significant differences in peripheral T-cell counts. The improved immune recovery was attributed to a more rapid regeneration of donor-type immune cells. Higher numbers of total thymocytes and signal joint T-cell receptor excision circles were observed in the higher dose stem cell recipients, suggesting that accelerated regeneration of T cells was due to enhanced thymopoiesis. (Blood. 2004;103:4344-4352)

Growth hormone accelerates immune recovery following allogeneic T-cell-depleted bone marrow transplantation in mice

OBJECTIVE

To test in a murine model whether recombinant human growth hormone can promote immune recovery after allogeneic T-cell-depleted bone marrow transplantation.

MATERIALS AND METHODS

Lethally irradiated (8.5 Gy) BALB/c mice (H2(d)) were transplanted with 5 x 10(6) T cell-depleted bone marrow cells from C57BL/6 mice (H2(b)). Recipient mice were injected intraperitoneally with recombinant human growth hormone (20 microg/dose/day) or saline for the first 4 weeks after transplantation. These animals were followed for phenotypic and functional immune recovery.

RESULTS

Administration of human recombinant growth hormone improved the CD4(+) T-cell counts in peripheral blood on day +14 (44+/-14 vs 33+/-7/microL blood, p<0.05) and day +21 (281+/-109 vs 187+/-76/microL blood, p<0.01) compared with the saline control. These differences were no longer significant by day +28 despite continued growth hormone administration. Similar effects were also observed on CD8(+) T cells and B220(+) B cells. The improvements in peripheral T-cell counts were at least partially as a result of enhanced thymopoiesis because there was an increase in total thymocytes after treatment with growth hormone. T-cell-depleted bone marrow recipients treated with growth hormone rejected the third-party grafts faster than those treated with saline control (median survival time: 20 days vs 26 days, p<0.05).

CONCLUSIONS

These data demonstrated that recombinant human growth hormone can accelerate phenotypic and functional immune reconstitution following allogeneic T-cell-depleted bone marrow transplantation in mice.

Transfer of allogeneic CD62L- memory T cells without graft-versus-host disease

The major challenge in allogeneic hematopoietic cell transplantation is how to transfer allogeneic T-cell immunity without causing graft-versus-host disease (GVHD). Here we report a novel strategy to selectively prevent GVHD by depleting CD62L(+) T cells (naive and a subset of memory T cells). In unprimed mice, CD62L(-) T cells (a subset of memory T cells) failed to proliferate in response to alloantigens (which the mice have never previously encountered) and were unable to induce GVHD in allogeneic hosts. CD62L(-) T cells contributed to T-cell reconstitution by peripheral expansion as well as by promoting T-cell regeneration from bone marrow stem/progenitor cells. CD62L(-) T cells from the animals previously primed with a tumor cell line (BCL1) were able to inhibit the tumor growth in vivo but were unable to induce GVHD in the third-party recipients. This novel technology may allow transfer of allogeneic recall antitumor and antimicrobial immunity without causing GVHD.