Stem cell transplantation for autoimmune diseases: what can we learn from experimental models?

Using animal models for autoimmune diseases, we have previously shown that allogeneic bone marrow transplantation (allo BMT) can be used to treat autoimmune diseases. Using cynomolgus monkeys, we have recently developed new BMT methods for the treatment of autoimmune diseases. The methods include the perfusion method (PM) for the collection of bone marrow cells (BMCs), and intra-bone marrow (IBM)-BMT for the direct injection of collected whole BMCs into the bone marrow cavity. The PM, in comparison with the conventional aspiration method, can minimize the contamination of BMCs with T cells from the peripheral blood. Therefore, without removing T cells, no graft-versus-host disease (GvHD) develops in the case of the PM. Since BMCs collected by the PM contain not only hemopoietic stem cells (HSCs) but also mesenchymal stem cells (MSCs), the injection of both cells directly into the bone marrow cavity (IBM-BMT) facilitates the engraftment of donor hemopoietic cells. In organ allografts with IBM-BMT, no graft failure occurs even if the radiation dose is reduced. In addition, IBM-BMT is applicable to regeneration therapy and various age-associated diseases such as osteoporosis, since it can efficiently recruit donor-derived normal MSCs. We have also found that IBM-BMT in conjunction with donor lymphocyte infusion can prevent GvHD, but suppress tumor growth. We believe that this strategy heralds a revolution in the field of transplantation (BMT and organ allografts) and regeneration therapy.     

Innovative BMT methods for intractable diseases

We have recently established new bone marrow transplantation (BMT) methods for the treatment of intractable diseases. The methods include the perfusion method (PM) for the collection of bone marrow cells, and intra-bone marrow (IBM)–BMT for the direct injection of collected whole bone marrow cells into the bone marrow cavity. The PM, in comparison with the conventional aspiration method, can minimize the contamination of bone marrow cells (BMCs) with T cells from the peripheral blood. Therefore, without removing T cells, no graft-versus-host disease (GvHD) develops in the case of the PM. Since BMCs collected by the PM contain not only hemopoietic stem cells (HSCs) but also mesenchymal stem cells (MSCs), the injection of both cells directly into the bone marrow cavity (IBM–BMT) facilitates the engraftment of donor hemopoietic cells. In organ allografts with IBM–BMT, no graft failure occurs even if the radiation dose is reduced. In addition, IBM–BMT is applicable to regeneration therapy and various age-associated diseases such as osteoporosis, since it can efficiently recruit donor-derived normal MSCs. Finally, we show that IBM–BMT in conjunction with donor lymphocyte infusion (DLI) can prevent GvHD but suppress tumor growth. We believe that this strategy heralds a revolution in the field of transplantation (BMT and organ allografts) and regeneration therapy. Presented at the First Robert A Good Society Symposium, St. Petersburg, FL 2006.     

The Future of Stem Cell Transplantation in Autoimmune Disease

We have previously found that conventional allogeneic bone marrow transplantation (allo BMT) can be used to treat various spontaneously developed autoimmune diseases in mice. In addition, we have found that autoimmune diseases can be transferred into the normal mice by conventional BMT from autoimmune-prone mice. Based on these findings, we have proposed that autoimmune diseases are “stem cell disorders.” To apply allo BMT to humans, we extensively carried out BMT to clarify which cells are essential for successful BMT, and finally found that three types of cells are essential for successful allogeneic BMT: (1) hemopoietic stem cells (HSCs), (2) natural suppressor cells, and (3) stromal cells (including mesenchymal stem cells, MSCs). We have very recently found that MSCs play a crucial role in preventing graft failure, since there is a major histocompatibility complex restriction between HSCs and MSCs. To recruit donor-derived MSCs, we have found that the injection of whole bone marrow cells into the bone marrow cavity (intra-bone marrow-BMT, IBM-BMT) is the best strategy for the treatment of various otherwise intractable diseases, including autoimmune diseases. In this review article, we provide evidence that IBM-BMT heralds a revolution in the field of transplantation and regeneration medicine.     

Analyses of very early hemopoietic regeneration after bone marrow transplantation: comparison of intravenous and intrabone marrow routes

In bone marrow transplantation (BMT), bone marrow cells (BMCs) have traditionally been injected intravenously. However, remarkable advantages of BMT via the intra-bone-marrow (IBM) route (IBM-BMT) over the intravenous route (IV-BMT) have been recently documented by several laboratories. To clarify the mechanisms underlying these advantages, we analyzed the kinetics of hemopoietic regeneration after IBM-BMT or IV-BMT in normal strains of mice. At the site of the direct injection of BMCs, significantly higher numbers of donor-derived cells in total and of c-kit(+) cells were observed at 2 through 6 days after IBM-BMT. In parallel, significantly higher numbers of colony-forming units in spleen were obtained from the site of BMC injection. During this early period, higher accumulations of both hemopoietic cells and stromal cells were observed at the site of BMC injection by the IBM-BMT route. The production of chemotactic factors, which can promote the migration of a BM stromal cell line, was observed in BMCs obtained from irradiated mice as early as 4 hours after irradiation, and the production lasted for at least 4 days. In contrast, sera collected from the irradiated mice showed no chemotactic activity, indicating that donor BM stromal cells that entered systemic circulation cannot home effectively into recipient bone cavity. These results strongly suggest that the concomitant regeneration of microenvironmental and hemopoietic compartments in the marrow (direct interaction between them at the site of injection) contributes to the advantages of IBM-BMT over IV-BMT. Disclosure of potential conflicts of interest is found at the end of this article.     

Intra-bone marrow injection of donor bone marrow cells suspended in collagen gel retains injected cells in bone marrow, resulting in rapid hemopoietic recovery in mice

We have recently developed an innovative bone marrow transplantation (BMT) method, intra-bone marrow (IBM)-BMT, in which donor bone marrow cells (BMCs) are injected directly into the recipient bone marrow (BM), resulting in the rapid recovery of donor hemopoiesis and permitting a reduction in radiation doses as a pretreatment for BMT. However, even with this IBM injection, some of the injected BMCs were found to enter into circulation. Therefore, we attempted to modify the method to allow the efficient retention of injected BMCs in the donor BM. The BMCs of enhanced green fluorescent protein transgenic mice (C57BL/6 background) were suspended in collagen gel (CG) or phosphate-buffered saline (PBS), and these cells were then injected into the BM of irradiated C57BL/6 mice. The numbers of retained donor cells in the injected BM, the day 12 colony-forming units of spleen (CFU-S) counts, and the reconstitution of donor cells after IBM-BMT were compared between the CG and PBS groups. The number of transplanted cells detected in the injected BM in the CG group was significantly higher than that in the PBS group. We next carried out CFU-S assays. The spleens of mice in the CG group showed heavier spleen weight and considerably higher CFU-S counts than in the PBS group. Excellent reconstitution of donor hemopoietic cells in the CG group was observed in the long term (>100 days). These results suggest that the IBM injection of BMCs suspended in CG is superior to the injection of BMCs suspended in PBS.     

Intra-bone marrow-bone marrow transplantation facilitates hemopoietic recovery including dendritic cells

In this report, we provide evidence using a serial bone marrow transplantation (BMT) protocol that intra-bone marrow (IBM)-BMT (IBM-BMT) can efficiently reconstitute the hemopoietic system with cells of donor origin, in contrast to conventional intravenous (IV)-BMT (IV-BMT). Furthermore, the hematolymphoid system of secondary recipients that had received bone marrow cells (BMCs) from primary recipients treated with IBM-BMT recovered earlier than that of the secondary recipients of BMCs from primary recipients treated with IV-BMT. This was the case when the Lin-/c-kit+ progenitor cells of the secondary and tertiary recipients were examined. These findings indicate that IBM-BMT can facilitate the development of not only cells of various lineages but also the effective generation and, more importantly, the maintenance of the progenitor cells. Furthermore, we show that IBM-BMT can reconstitute the dendritic cell (DC) subsets (myeloid and lymphoid DCs), which are critical for the initiation of both adaptive and innate immune responses. The frequency of both myeloid and lymphoid DC subsets was approximately equal to that of normal age-matched untreated controls and, after second and third BMT, this ratio was close to that observed in the normal controls. However, the lymphoid DCs were clearly reduced in the secondary and tertiary recipients of BMCs from mice that had received IV-BMT. Therefore, the development of DC subsets is also normally maintained in the IBM-BMT group.     

Crucial role of donor-derived stromal cells in successful treatment for intractable autoimmune diseases in mrl/lpr mice by bmt via portal vein

We have recently established a new bone marrow transplantation (BMT) method for the treatment of intractable autoimmune diseases in MRL/lpr mice; the method consists of fractionated irradiation (5.5 Gy x 2), followed by BMT of whole bone marrow cells (BMCs) from allogeneic C57BL/6 mice via the portal vein (abbreviated as 5.5 Gy x 2 + PV). In the present study, we investigate the mechanisms underlying the early engraftment of donor-derived cells in MRL/lpr mice by this method. In the mice treated with this method, the number of donor-derived cells possessing the mature lineage (Lin) markers rapidly increased in the BM, spleen, and liver; almost 100% were donor-derived cells by 14 days after the treatment. The number of donor-derived hemopoietic progenitor cells (defined as c-kit(+)/Lin(-) cells) increased in the BMCs, hepatic mononuclear cells, and especially spleen cells by 14 days after the treatment. Simultaneously, hemopoietic foci adjoining donor-derived stromal cells were observed in the liver when injected via the PV, but not via the peripheral vein (i.v.). When adherent cell-depleted BMCs were injected via the PV, recipients showed a marked reduction in the survival rate. However, when mice were transplanted with adherent cell-depleted BMCs with cultured stromal cells, all the recipients survived. These findings suggest that not only donor hematopoietic stem cells (HSCs) but also donor stromal cells administered via the PV were trapped in the liver, resulting in the early engraftment of donor HSCs in cooperation with donor-derived stromal cells. This new strategy to facilitate the early recovery of hemopoiesis would therefore be of great advantage in human application.     

Enhancement of allogeneic hematopoietic stem cell engraftment and prevention of GVHD by intra-bone marrow bone marrow transplantation plus donor lymphocyte infusion

We examined the effect of intra-bone marrow (IBM)-bone marrow transplantation (BMT) in conjunction with donor lymphocyte infusion (DLI) on the engraftment of allogeneic bone marrow cells (BMCs) in mice. Recipients that had received 6 Gy of radiation completely rejected donor BMCs, even when IBM-BMT was carried out. However, when BMCs were IBM injected and donor peripheral blood mononuclear cells (PBMNCs) were simultaneously injected intravenously (DLI), donor cell engraftment was observed 7 days after BMT and complete donor chimerism continued thereafter. It is of interest that the cells of recipient origin did not recover, and that the hematolymphoid cells, including progenitor cells (Lin-/c-kit+ cells) in the recipients, were fully reconstituted with cells of donor origin. The cells in the PBMNCs responsible for the donor BMC engraftment were CD8+. Recipients that had received 6 Gy of radiation, IBM-BMT, and DLI showed only a slight loss of body weight, due to radiation side effects, and had no macroscopic or microscopic symptoms of graft-versus-host disease. These findings suggest that IBM-BMT in conjunction with DLI will be a valuable strategy for allogeneic BMT in humans.     

A novel method of bone marrow transplantation (BMT) for intractable autoimmune diseases

We have previously proposed that autoimmune diseases are hemopoietic stem cell (HSC) disorders. In this review article, we provide evidence that most age-associated diseases such as osteoporosis are mesenchymal stem cell (MSC) disorders and, based on this evidence, we propose a new concept of "stem cell disorders (SCDs)", including HSC and MSC disorders. To treat SCDs, we have recently developed a new strategy (intra-bone marrow-bone marrow transplantation: IBM-BMT) for replacing the abnormal stem cells of recipients with donor-derived normal stem cells (both HSCs and MSCs). We here show that this strategy not only can be used to treat SCDs but is also applicable to organ transplantation, since IBM-BMT can induce tolerance (full chimerism) without the need for immunosuppressants even when radiation doses as the conditioning regimen of BMT are reduced to less than 5.0 Gy x 2, which is equivalent to one shot of 8 Gy (a sublethal dose). We believe that this strategy heralds a revolution in the field of transplantation (BMT and organ transplantation) and regeneration therapy.     

Simultaneous injection of bone marrow cells and stromal cells into bone marrow accelerates hematopoiesis in vivo

We have previously demonstrated that stromal cells can support the proliferation and differentiation of hematopoietic cells in vitro and in vivo and that a major histocompatibility complex restriction exists between hematopoietic stem cells and stromal cells. We have also found that intra-bone marrow (IBM) injection of allogeneic bone marrow cells (BMCs) leads to more rapid reconstitution of hematopoietic cells than intravenous injection. In the present study, we examine the effect of simultaneous injection of stromal cells and BMCs into the same bone marrow on the recovery of donor hematopoietic cells and demonstrate that simultaneous IBM injection of BMCs plus stromal cells is more effective in reconstituting recipients with donor hematopoietic cells than intravenous injection of BMCs plus stromal cells or IBM injection of BMCs alone.     

High-dose total body irradiation and bone marrow cells may improve efficiency of bone marrow transplantation therapy in treating type 1 diabetes

Bone marrow transplantation (BMT) has been used to treat autoimmune diseases for many years. Insulin-dependent diabetes mellitus (IDDM), also called type 1 diabetes mellitus (T1DM), is a T cell-mediated autoimmune disease resulting from a selective destruction of pancreatic islet beta cells. Recently, T1D has been a common significant cause of morbidity and mortality. However, whether BMT can be used to treat T1DM is still controversial. During BMT procedure, recipients underwent total body irradiation (TBI) and subsequent bone marrow cells (BMCs) infusion, in which TBI kills off the most T lymphocytes and BMCs stimulates hematopoiesis and immune reconstitution. We suggest that high-dose TBI and BMCs may improve efficiency of BMT therapy in T1DM treatment.     

Allogeneic intra-bone marrow transplantation prevents rheumatoidarthritis in SKG/Jcl mice

The treatment of autoimmune diseases by allogeneic bone marrow transplantation remains a promising therapeutic avenue. However, more intensive studies on murine models are essential before application to a large number of human patients. In particular, the use of bone marrow transplantation to treat rheumatoid arthritis has been problematic. We have taken advantage of the SKG/Jcl mouse that develops a chronic T cell-mediated autoimmune disease that mimics rheumatoid arthritis which attempted to prevent the development of immunopathology in these mice by allogeneic bone marrow transplantation (BMT). In particular, we utilized our unique technology in which bone marrow cells (BMCs) of control C57BL/6J mice are directly injected into the bone marrow cavity in the tibia of SKG mice (intra-bone marrow [IBM]-BMT). As controls, SKG/Jcl mice were transplanted with whole BMCs from syngeneic SKG mice. Importantly, 12 months after IBM-BMT [B6 → SKG] demonstrated no evidence of arthritis, whereas the control [SKG → SKG] mice demonstrated, the expected immunopathology of a rheumatoid arthritis-like condition. Further, hematolymphoid cells in [B6 → SKG] mice were reconstituted by donor-derived cells and the percentages of Treg (Foxp3⁺/CD4⁺) cells, the percentages of receptor activator of nuclear factor-κB ligand (RANKL)⁺ cells on the CD4⁺T cells and the serum levels of tumor necrosis factor-α, interleukin-1 and interleukin-6 were normalized in the [B6 → SKG] mice. These data suggest that IBM-BMT is a viable method of immunological manipulation that suppresses the severe joint destruction and bone absorption in SKG/Jcl mice and lends further credence to the use of this methodology in humans with intractable rheumatoid arthritis.     

Long-term (>1 year) analyses of chimerism and tolerance in mixed allogeneic chimeric mice using normal mouse combinations

We examined the induction of tolerance using pancreas allografts over the long term (>1 year) in mice for the human application of mixed allogeneic bone marrow transplantation (BMT). T cell-depleted BM cells (BMCs) of C57BL/6 (B6) and C3H/He (C3H) mice were transplanted at various ratios into lethally irradiated B6 mice. The percentages of C3H cells in the chimeric mice gradually decreased, finally declining to only a small percentage, except when the ratio of donor to recipient BMCs was 100:1. However, despite the marked decreases in C3H-type cells, all the pancreas allografts of C3H mice were accepted when more than 1% C3H cells were detected in the peripheral blood. To examine the relationships between percentages of transplanted donor cells and acceptance of pancreas allografts, various percentages of donor and recipient BMCs (5% to 30%) were transplanted. It was found that more than 10% donor cells were necessary for the pancreas allografts to be accepted. In vitro assays for mixed lymphocyte reaction and generation of cytotoxic T-lymphocytes revealed that spleen cells in chimeric mice accepting pancreas allografts are tolerant to both host-type and donor-type major histocompatibility complex (MHC) determinants, but show a vigorous responsiveness to third-party MHC determinants. Since donor-type hemopoietic stem cells (HSCs) were detected in the BM and the liver of the chimeric mice, donor-derived HSCs and donor-derived hematolymphoid cells are responsible for the induction of tolerance. It should be noted that the percentage of donor-type HSCs is higher in the liver (6.2%) than in the BM (0.9%).     

Mesenchymal stem cells cooperate with bone marrow cells in therapy of diabetes

Several recent studies have suggested that the adult bone marrow harbors cells that can influence beta-cell regeneration in diabetic animals. Other reports, however, have contradicted these findings. To address this issue, we used an animal model of type 1 diabetes in which the disease was induced with streptozotocin in mice. Freshly prepared sex-mismatched bone marrow cells (BMCs) and syngeneic or allogeneic mesenchymal stem cells (MSCs) were concomitantly administrated into sublethally irradiated diabetic mice. Blood glucose and serum insulin concentrations rapidly returned to normal levels, accompanied by efficient tissue regeneration after a single injection of a mixture of 10(6) BMCs per 10(5) MSCs. Neither BMC nor MSC transplantation was effective alone. Successful treatment of diabetic animals was not due to the reconstitution of the damaged islet cells from the transplant, since no donor-derived beta-cells were found in the recovered animals, indicating a graft-initiated endogenous repair process. Moreover, MSC injection caused the disappearance of beta-cell-specific T lymphocytes from diabetic pancreas. Therefore, we suggest that two aspects of this successful treatment regimen operate in parallel and synergistically in our model. First, BMCs and MSCs induce the regeneration of recipient-derived pancreatic insulin-secreting cells. Second, MSCs inhibit T-cell-mediated immune responses against newly formed beta-cells, which, in turn, are able to survive in this altered immunological milieu. Thus, the application of this therapy in human patients suffering from diabetes and/or other tissue destructive autoimmune diseases may be feasible.     

Lack of correlation between an assay used to determine early marrow allograft rejection and long-term chimerism after murine allogeneic bone marrow transplantation: effects of marrow dose.

The acute rejection of bone marrow (BM) allografts by host effectors can occur within a short period after BM transplantation (BMT) in lethally irradiated mice. Common assays used to ascertain engraftment/resistance involve measuring the growth of granulocyte/monocyte progenitors (colony-forming unit-granulocyte-macrophage) in vitro or splenocyte proliferation assessed by radioisotope incorporation in vivo 5 to 8 days after BMT. However, the correlation of the long-term outcome of BMT with the kinetics of recovery by using the dose of allogeneic BM cells (BMCs) that leads to early rejection as determined by the in vitro assessment has not been extensively studied. Thus, to investigate whether the early rejection of donor BMCs is an indication of a long-term engraftment failure, C57BL/6 (H2b) mice were lethally irradiated and transplanted with various doses of BALB/c (H2d) BMCs. The short-term engraftment of donor precursors (colony-forming unit-granulocyte-macrophage), the kinetics of hematopoietic cell recovery, the extent of donor chimerism, and the proportion of the recipients with long-term survival were determined. The results show that the kinetics and extent of hematopoietic cell recovery were significantly delayed in mice receiving limiting doses of BMCs that were rejected or severely resisted at day 8 after BMT. However, a proportion of these mice survived up to 98 days after BMT with mixed chimerism or donor chimerism. This study demonstrates that early rejection of BM precursors, as assessed by measurement of myeloid progenitors in the spleen after BMT, does not always correlate with the long-term outcome of the marrow allograft and that significant variability is inherent in the extent of chimerism when threshold amounts of BMCs are used.     

Successful acceptance of adult liver allografts by intra-bone marrow-bone marrow transplantation

Previously, we have shown that liver allografts obtained from the fetus or young mice are accepted when bone marrow cells (BMCs) from adult mice of the same strain are co-grafted. However, for practical clinical use, it is more convenient to obtain both BMCs and liver from the same adult donors. C57BL/6 mice were irradiated with a single high-dose irradiation or two low-dose irradiations and injected with donor BALB/c (8 weeks old) BMCs intravenously (IV-BMT) or directly into the recipient BM cavity (IBM-BMT). Liver tissues taken from the same donor were, on the same day, engrafted under the kidney capsules. Higher survival rates and more complete reconstitution of donor cells were achieved in the IBM-BMT group than in the IV-BMT group, and this was the case in both irradiation protocols. The acceptance of donor liver tissue was seen in all mice in which hematolymphoid cells were replaced by donor-type cells. The liver grafts of the reconstituted mice showed normal morphology and stained positively with anti-albumin antibody and Periodic Acid Schiff (PAs) staining, indicating that the grafted livers were accepted, had grown, and were functioning. These results demonstrate that the acceptance of allogeneic liver can be achieved by cografting donor BMCs via the IBM route.     

Prevention of graft-versus-host disease by intrabone marrow injection of donor T cells: involvement of bone marrow stromal cells

We have developed a new and effective method for bone marrow transplantation (BMT): bone marrow cells (BMCs) are injected directly into the bone marrow (BM) cavity of recipient mice. The intrabone marrow injection of BMCs (IBM-BMT) greatly facilitates the engraftment of donor-derived cells, and IBM-BMT can attenuate graft-versus-host reaction (GVHR), in contrast to conventional intravenous BMT (i.v.-BMT). Here, we examine the mechanisms underlying the inhibitory effects of IBM-BMT on GVHR using animal models where GVHR is elicited. Recipient mice (C57BL/6) were irradiated and splenic T cells (as donor lymphocyte infusion: DLI) from major histocompatibility complex-disparate donors (BALB/c) were injected directly into the BM cavity (IBM-DLI) or injected intravenously (i.v.-DLI) along with IBM-BMT. The BM stromal cells (BMSCs) from these recipients were collected and related cytokines were examined. The recipient mice that had been treated with IBM-BMT + i.v.-DLI showed severe graft-versus-host disease (GVHD), in contrast to those treated with IBM-BMT + IBM-DLI. The suppressive activity of BMSCs in this GVHD model was determined. The cultured BMSCs from the recipients treated with IBM-BMT + IBM-DLI suppressed the proliferation of responder T cells remarkably when compared with those from the recipients of IBM-BMT + i.v.-DLI in mixed leucocyte reaction. Furthermore, the level of transforming growth factor-beta and hepatocyte growth factor in cultured BMSCs from IBM-BMT + IBM-DLI increased significantly when compared with those from the recipients of IBM-BMT + i.v.-DLI. Thus, the prevention of GVHD observed in the recipients of IBM-BMT + IBM-DLI was attributable to the increased production of immunosuppressive cytokines from BMSCs after interaction with host reactive T cells (in DLI).     

Choroidal neovascularization is provided by bone marrow cells

Choroidal neovascularization (CNV) is a known cause of age-related macular degeneration (ARMD). Moreover, the most common cause of blindness in the elderly in advanced countries is ARMD with CNV. It has recently been shown that bone marrow cells (BMCs) can differentiate into various cell lineages in vitro and in vivo. Adults maintain a reservoir of hematopoietic stem cells included in BMCs that can enter the circulation to reach various organs in need of regeneration. It has recently been reported that endothelial progenitor cells (EPCs) included in BMCs are associated with neovascularization. We examine the role of BMCs in CNV using a model of CNV in adult mice. Using methods consisting of fractionated irradiation (6.0 Gy x 2) followed by bone marrow transplantation (BMT), adult mice were engrafted with whole BMCs isolated from transgenic mice expressing enhanced green fluorescent protein (EGFP). Three months after BMT, we confirmed that the hematopoietic cells in the recipients had been completely replaced with donor cells. We then carried out laser photocoagulation to induce CNV in chimeric mice (donor cells >95%). Two weeks after the laser photocoagulation, by which time CNV had occurred, immunohistochemical examination was carried out. The vascular wall cells of the CNV expressed both EGFP and CD31. These findings indicate that newly developed blood vessels in the CNV are derived from the BMCs and suggest that the inhibition of EPC mobilization from the bone marrow to the eyes could be a new approach to the fundamental treatment of CNV in ARMD.     

A new strategy for treatment of malignant tumor: intra-bone marrow-bone marrow transplantation plus CD4- donor lymphocyte infusion

Donor lymphocyte infusion (DLI) is clinically used for the treatment of malignant tumors. We have found recently that intra-bone marrow-bone marrow transplantation (IBM-BMT) can be used to treat various autoimmune diseases, even when radiation doses are reduced. In addition, recently we have found that IBM-BMT can prevent not only graft failure but also graft-versus-host disease (GvHD). Based on these findings, we attempted to prevent and treat the progression of a tumor (Meth-A cell line: BALB/c-derived fibrosarcoma) by DLI plus IBM-BMT. When the tumors had grown to approximately 10 x 10 mm, the tumor-bearing BALB/c (H-2(d)) mice were irradiated with 5 Gy, and whole spleen cells from C57BL/6J (B6) (H-2(b)) mice (as DLI) were then intravenously injected into the BALB/c mice. Simultaneously, bone marrow cells (BMCs) from B6 mice were injected directly into the bone marrow cavity of the BALB/c mice (IBM-BMT). The tumors decreased in size, but the mice died of GvHD. However, when CD4(+) T-cell-depleted spleen cells were used for DLI, the recipients showed only mild GvHD and survived longer, due to the slow growth of the tumor. In contrast, when CD8(+) T-cell-depleted spleen cells were used for DLI, the recipients showed more severe GvHD than those injected with whole spleen cells. These results suggest that IBM-BMT plus DLI (the depletion or reduction of a certain cell population like CD4(+) T cells) could be helpful to suppress both GvHD and tumor growth.     

骨髓腔内途径脐血与间质干细胞共移植对造血重建的实验研究

目的：探讨骨髓腔内输注（IBM）脐血与间质干细胞（MSCs）对大鼠造血重建、骨髓MSCs恢复的影响，并研究供体MSCs植入状态以探讨MSCs的作用机制。方法：BrdU标记F344大鼠骨髓MSCs通过双侧胫骨IBM或尾静脉注射（IV）与胎鼠及新生大鼠外周血（FNPB）共移植Wistar雌鼠。监测受鼠存活状况、造血免疫重建、HSCs植入水平及骨髓MSCs恢复情况，并以免疫荧光法检测受鼠骨髓MSCs的来源。结果：(1)2个共移植组60 d存活率均为100%，单纯FNPB移植组仅为66.7%。(2)共移植组的外周血象、骨髓造血干祖细胞集落产率明显高于单纯FNPB移植组，尤以骨髓腔共移植组最佳。(3)2个共移植组的HSCs植入水平无统计学差异，而骨髓腔共移植组明显高于单纯FNPB移植组（P＜0.05）。(4)30 d时各移植组MSCs的增殖能力未达正常水平，但仍以骨髓腔共移植组的恢复情况最佳（P＜0.05）。(5)仅少部分受体可发现供、受体源性MSCs嵌合。 结论：脐血与MSCs共移植可促进受体骨髓MSCs恢复和造血重建，提高HSCs植入率；IBM途径应用安全，促进造血恢复的作用优于IV途径。