Intra-bone Marrow-bone Marrow Transplantation Research Articles

Progress towards xenogenic tolerance.

To describe the most recent progress towards tolerance in xenotransplantation. Mixed chimerism and thymic transplantation have been used to promote tolerance in xenotransplantation models. Intra-bone bone marrow transplantation is a recent advance for mixed chimerism, which promotes longer lasting chimerism and early graft function of subsequent organ transplantation. The hybrid thymus, an advancement to the vascularized thymokidney and vascularized thymic lobe, is being developed to allow for both donor and recipient T-cell selection in the chimeric thymus, encouraging tolerance to self and donor while maintaining appropriate immune function. Regulatory T cells show promise to promote tolerance by suppressing effector T cells and by supporting mixed chimerism. Monoclonal antibodies such as anti-CD2 may promote tolerance through suppression of CD2+ effector and memory T cells whereas Tregs, which express lower numbers of CD2, are relatively spared and might be used to promote tolerance. These findings contribute major advances to tolerance in xenotransplantation. A combination of many of these mechanisms will likely be needed to have long-term tolerance maintained without the use of immunosuppression.

Intra-bone Bone Marrow Transplantation in Pig-to-Nonhuman Primates for the Induction of Tolerance Across Xenogeneic Barriers.

Mixed chimerism and thymic tissue transplantation strategies have achieved xenogeneic tolerance in pig-to-mouse models, and both have been extended to pig-to-baboon models. A mixed chimerism strategy has shown promise toward inducing tolerance in allogeneic models in mice, pigs, nonhuman primates (NHP), humans, and a rat-to-mouse small animal xeno-model. However, even though α-1,3-galactosyltransferase gene knockout (GalTKO) pigs have been used as bone marrow (BM) donors, direct intravenous injection of porcine BM cells was detected for only up to 4days (peripheral macro-chimerism) in one case, and the rest lost chimerism within 2days.Recent data in allogeneic models demonstrated that direct injection of donor BM cells into recipient BM spaces (intra-bone bone marrow transplantation: IBBMTx) produces rapid reconstitution and a higher survival rate compared to i.v. injection. In order to minimize the loss of injected porcine BM peripherally before reaching the BM space, Yamada developed a xeno-specific regimen including IBBMTx coated with a collagen gel matrix in a preclinical pig-to-baboon model (Yamada IBBMTx). This strategy aims to achieve improved, persistent macro-chimerism as well as engraftment of BM across a xenogeneic barrier. The initial study published in 2015 demonstrated that this IBBMTx strategy leads to markedly prolonged peripheral macro-chimerism detectable for up to 23days. Furthermore, a more recent study using human CD47-transgenic (Tg) GalTKO pigs as xeno-donors achieved long-lasting macro-chimerism >60days with evidence of reduction of anti-pig natural antibodies (nAb). This is the longest macro-chimerism that has ever been achieved in a preclinical large animal xenotransplant model to date. In this chapter, we introduce a brief summary of our achievements in regard to successful tolerance induction by utilizing our novel strategy of IBBMTx as well as describe the step-by-step methodology of surgical and in vitro procedures that are required for this project.

Intra-bone bone marrow transplantation from hCD47 transgenic pigs to baboons prolongs chimerism to >60 days and promotes increased porcine lung transplant survival.

We have recently demonstrated that human-CD47 (hCD47) expressed on endothelial cells of porcine lung xenografts extended median graft survival from 3.5days to 8.7days in baboons. Intra-bone bone marrow transplantation (IBBMTx) in a pig-to-baboon model was previously shown to markedly prolong the duration of macrochimerism up to 21days from 1 to 4days by intravenous BMTx. We now examined whether the use of hCD47 transgenic (Tg) BM further prolonged the duration of chimerism following IBBMTx. We then tested if lung xenograft survival was prolonged following IBBMTx. Baboons received GalTKO-hCD47/hCD55Tg (n=5) or -hCD55Tg (n=1) or -hCD46/HLA-E Tg (n=1) pig IBBMTx. Macrochimerism, anti-pig T cells and antibody responses were assessed. Animals received lung xenografts from either hCD47+ or hCD47- porcine lungs 1-3months later. All baboons that received hCD47Tg porcine IBBM maintained durable macrochimerism >30days, and two maintained chimerism for >8weeks. Notably, anti-pig antibody levels decreased over time and anti-pig cellular unresponsiveness developed following IBBMTx. Lungs from hCD47Tg IBBMTx matched pigs were transplanted at day 33 or day 49 after IBBMTx. These animals showed extended survival up to 13 and 14days, while animals that received lungs from hCD47 negative pigs displayed no prolonged survival (1-4days). This is the first report demonstrating durable macrochimerism beyond 8weeks, as well as evidence for B cell tolerance in large animal xenotransplantation. Using hCD47Tg pigs as both IBBMTx and lung donors prolongs lung xenograft survival. However, additional strategies are required to control the acute loss of lung xenografts.

Durable Macrochimerism (>8 weeks) and Pig-Specific T and B Cell Unresponsiveness Following hCD47+ Transgenic GalTKO Pig Intra-Bone Bone Marrow Transplantation in Baboons

Background Recent data have suggested that low levels of preformed anti-non-Gal natural antibody (nAb) limit xenograft survival. Durable mixed xenogeneic chimerism resulted in tolerance of human T cell-independent B cells that produce xenoantibodies, including anti-non-Gal nAb, in mouse models. However, previous attempts at intravenous (IV) α-1,3-galactocyltransferase knockout (GalTKO) pig bone marrow (BM) transplantation (Tx) into non-human primates have been associated with very short-lived chimerism (<24 hours in most cases). In order to achieve improved engraftment with more persistent chimerism, we have recently developed an intra-bone BM (IBBM) Tx strategy in a pig-to-baboon model. We have reported continuous peripheral blood macrochimerism for up to 13 days (mean 7.7 days; range 3–13) post-IBBM/BM-Tx (n=6) and in three animals, macrochimerism reappeared at days 10, 14 and 21 (Am J Transplant 2015). Recent data has suggested that incompatibility between CD47 and SIRPα causes phagocytosis of porcine cells. In this study, we examined whether the use of BM cells from human CD47 (hCD47) transgenic pigs further improves durable chimerism and assessed anti-pig antibody responses following BM Tx,Methods: Four baboons received GalTKO/human CD47(hCD47)/hCD55 pig BM cells, and one received GalTKO/hCD55 porcine BM cells with a conditioning regimen consisting of whole body irradiation thymic, irradiation, ATG, and Rituximab followed by anti-CD40L antibody and MMF. Approximately 2/3 of BM cells were infused intraosseously and the remainder intravenously. Macrochimerism, anti-pig T cells responses, and anti-pig antibody responses were assessed following IBBM Tx. Results were compared with those from baboons that received GalTKO porcine BM cells without any other gene modification (n=6). Results As shown in the Figure (left panel), all four baboons that received hCD47+/hCD55+ porcine BM using the IBBM Tx method maintained durable macrochimerism for >50 days, and two of the 4 maintained blood levels above 1.6%, even at 8 weeks following IBBMTx (red line in the left panel of Fig). We also confirmed macrochimerism in recipients’ BM. A baboon that received hCD55+ but hCD47-negative porcine BM cells also had a slightly higher % of chimerism than GalTKO alone porcine BM cells in the first 3 weeks, but the duration was similar to GalTKO alone porcine BM cells (Blue line vs black line in the left panel of Fig). All recipients of IBBM Tx lost their anti-pig T cell responses in vitro and showed no development of elicited anti-pig ab. Notably, anti-pig nonGal nAb levels in three of 4 recipients of hCD47+/hCD55+ porcine BM cells declined markedly following IBBM Tx (right panel of Fig). Conclusion To our knowledge, this is the first demonstration of (1) durable macrochimerism beyond 8 weeks and (2) reduction of anti-non Gal nAb levels following hCD47+/hCD55+ GalTKO porcine IBBMTx in preclinical pig-to-non-human primate models. The results suggest that IBBMTx using hCD47+ porcine BM is a potent strategy to induce pig-specific T and B cell tolerance across xenogeneic barriers..NIH P01AI45897.:

Specially modified stromal and immune microenvironment in injected bonemarrow following intrabone transplantation facilitates allogeneichematopoietic stem cell engraftment.

For allogeneic hematopoietic stem cell transplantation (HSCT), the first key step is the engraftment of hematopoietic stem cells (HSCs) across the major histocompatibility complex (MHC) barrier. Intrabone bone marrow transplantation (IBBMT) could replace more recipient stromal cells with donor cells and facilitate allogeneic organ transplantation compared with the conventional intravenous approach. However, it remains unknown whether and how IBBMT reconstructs the immune microenvironment for allogeneic HSCs. We explored where the BM microenvironment changes by determining BM stromal cell chimerism and measuring the change in CXCL-12 expression and regulatory Tcells in recipient BM. We found that most stromal cells were replaced by allogeneic cells in the injected BM, with higher expression of immune regulatory cytokines (interleukin-10) compared with the contralateral BM and the intravenous group BM. This difference was independent of injury caused by intrabone injection. Consistent with the microenvironment modification, the allogeneic the engraftment rate and reconstitution capacity of HSCs were enhanced in the injected BM compared with the contralateral BM and intravenous group BM. Surgical removal of the injected bone at 7days rather than 21days reduced the levels of allogeneic granulocytes and HSCs in the peripheral blood. In conclusion, IBBMT specially modifies stromal cells in the injected BM which provide immune protective cues that improve the engraftment of allogeneic HSCs in an early period.

Fetal Liver-Derived Stem Cells Ameliorate Immune Functions in Leptin Receptor-Deficient Mice

Fetal liver (FL) contains hepatic stem cells, hematopietic stem cells, and mesenchymal stem cells, as well as pluripotent stem cells and very small embryonic-like stem cells. FL has thus been available as a source of stem cells for regenerative medicine. Our previous report suggested that combining FL cell transplantation with the transplantation of fetal thymus prevented tumor growth in tumor-bearing mice. Moreover, in animal models, intra bone marrow-bone marrow transplantation (IBM-BMT) has proven to be the best approach for allogenic BMT. We here propose that transplanting FL cells by IBM-BMT can improve immune functions in leptin receptor-deficient (db/db) mice. FL cells were collected from FLs of C57BL/6 mice at 16 days post coitum, and then transplanted by IBM-BMT to leptin receptor deficent mice, an animal model of type 2 diabetes with obesity. Our results showed that the body weight was significantly lowered in the treated db/db mice than in the sham-treated db/db mice. The plasma IL-6 level significantly decreased and adiponectin level significantly increased after the transplantation of FL cells. Blood glucose levels also significantly decreased although not to within the normal range. This is the first report that the transplantation of FL cells may improve immune function, resulting in increased adiponectin levels, and decreased body weight in db/db mice. DisclosuresNo relevant conflicts of interest to declare.

High Incidence of Xenogenic Bone Marrow Engraftment in Pig-to-Baboon Intra-Bone Bone Marrow Transplantation

Previous attempts of α-1,3-galactocyltransferase knockout (GalTKO) pig bone marrow (BM) transplantation (Tx) into baboons have demonstrated a loss of macro-chimerism within 24 h in most cases. In order to achieve improved engraftment with persistence of peripheral chimerism, we have developed a new strategy of intra-bone BM (IBBM) Tx. Six baboons received GalTKO BM cells, with one-half of the cells transplanted into the bilateral tibiae directly and the remaining cells injected intravenously (IBBM/BM-Tx) with a conditioning immunosuppressive regimen. In order to assess immune responses induced by the combined IBBM/BM-Tx, three recipients received donor SLA-matched GalTKO kidneys in the peri-operative period of IBBM/BM-Tx (Group 1), and the others received kidneys 2 months after IBBM/BM-Tx (Group 2). Peripheral macro-chimerism was continuously detectable for up to 13 days (mean 7.7 days; range 3-13) post-IBBM/BM-Tx and in three animals, macro-chimerism reappeared at days 10, 14 and 21. Pig CFUs, indicating porcine progenitor cell engraftment, were detected in the host BM in four of six recipients on days 14, 15, 19 and 28. In addition, anti-pig unresponsiveness was observed by in vitro assays. GalTKO/pCMV-kidneys survived for extended periods (47 and 60 days). This strategy may provide a potent adjunct for inducing xenogeneic tolerance through BM-Tx.

Increased recruitment of bone marrow-derived cells into the brain associated with altered brain cytokine profile in senescence-accelerated mice.

Bone marrow-derived cells enter the brain in a non-inflammatory condition through the attachments of choroid plexus and differentiate into ramified myeloid cells. Neurodegenerative conditions may be associated with altered immune-brain interaction. The senescence-accelerated mouse prone 10 (SAMP10) undergoes earlier onset neurodegeneration than C57BL/6 (B6) strain. We hypothesized that the dynamics of immune cells migrating from the bone marrow to the brain is perturbed in SAMP10 mice. We created 4 groups of radiation chimeras by intra-bone marrow-bone marrow transplantation using 2-month-old (2 mo) and 10 mo SAMP10 and B6 mice as recipients with GFP transgenic B6 mice as donors, and analyzed histologically 4 months later. In the [B6 → 10 mo SAMP10] chimeras, more ramified marrow-derived cells populated a larger number of discrete brain regions than the other chimeras, especially in the diencephalon. Multiplex cytokine assays of the diencephalon prepared from non-treated 3 mo and 12 mo SAMP10 and B6 mice revealed that 12 mo SAMP10 mice exhibited higher tissue concentrations of CXCL1, CCL11, G-CSF, CXCL10 and IL-6 than the other groups. Immunohistologically, choroid plexus epithelium and ependyma produced CXCL1, while astrocytic processes in the attachments of choroid plexus expressed CCL11 and G-CSF. The median eminence produced CXCL10, hypothalamic neurons G-CSF and tanycytes CCL11 and G-CSF. These brain cytokine profile changes in 12 mo SAMP10 mice were likely to contribute to acceleration of the dynamics of marrow-derived cells to the diencephalon. Further studies on the functions of ramified marrow-derived myeloid cells would enhance our understanding of the brain-bone marrow interaction.

Fetal Liver-Derived Stem Cells Ameliorate Adipocyte Functions in Obese Mice

Fetal liver (FL) contains hepatic stem cells, hematopietic stem cells, and mesenchymal stem cells, as well as pluripotent stem cells and very small embryonic-like stem cells. FL has thus been available as a source of stem cells for regenerative medicine. Our previous report suggested that combining FL cell transplantation with the transplantation of fetal thymus prevented tumor growth in tumor-bearing mice. Moreover, in animal models, intra bone marrow-bone marrow transplantation (IBM-BMT) has proven to be the best approach for allogenic BMT. We here propose that transplanting FL cells by IBM-BMT can improve adipocyte functions in obese mice. FL cells were collected from FLs of C57BL/6 mice at 16 days post coitum, and then transplanted by IBM-BMT to db/db mice, an animal model of type 2 diabetes with obesity. Our results showed that the body weight was significantly lower in the treated db/db mice than in the sham-treated db/db mice. The plasma IL-6 level significantly decreased and adiponectin level significantly increased after the transplantation of FL cells. Blood glucose levels also significantly decreased although not to within the normal range. This is the first report that the transplantation of FL cells may improve adipocyte functions, resulting in decreased body weight in obese mice.

Stem cell transplantation upregulates Sirt1 and antioxidant expression, ameliorating fatty liver in type 2 diabetic mice.

Nonalcoholic fatty liver disease (NAFLD) is associated with insulin resistance, oxidative stress, and obesity. The db/db mouse model displays increased levels of insulin resistance, obesity, and an over-accumulation of hepatic triglycerides, making it an excellent model for studying NAFLD. In db/db mice, intra-bone marrow-bone marrow transplantation plus thymus transplantation (IBM-BMT+TT) improves type 2 diabetes mellitus (T2 DM) by normalizing the T-cell imbalance. We hypothesized that this approach would improve Sirt1 expression in the liver and benefit liver development.The db/db mice were treated with IBM-BMT+TT, and plasma MCP-1, IL-6, adiponection, LDL, Sirt1, and HO-1 levels were then assessed. Stem cell transplantation decreased the levels of plasma inflammatory cytokines and LDL while it increased the expression of Sirt1 and HO-1, resulting in decreased progression of fatty liver. Moreover, Sirt1 and HO-1 expression were both detected in the thymus and many HO-1-positive cells were observed in the bone marrow.This is the first report of stem cell transplantation improving the antioxidant function in the liver, thymus, and bone marrow of db/db mice by increasing the levels of Sirt1 and HO-1. This approach may prove useful in the treatment of nonalcoholic steatohepatitis and its clinical manifestations.

Intractable diseases treated with intra-bone marrow-bone marrow transplantation.

Bone marrow transplantation (BMT) is used to treat hematological disorders, autoimmune diseases (ADs) and lymphoid cancers. Intra bone marrow-BMT (IBM-BMT) has been proven to be a powerful strategy for allogeneic BMT due to the rapid hematopoietic recovery and the complete restoration of T cell functions. IBM-BMT not only replaces hematopoietic stem cells (HSCs) but also mesenchymal stromal cells (MSCs). MSCs are multi-potent stem cells that can be isolated from bone marrow (BM), umbilical cord blood (UCB), and adipose tissue. MSCs play an important role in the support of hematopoiesis, and modify and influence the innate and adaptive immune systems. MSCs also differentiate into mesodermal, endodermal and ectodermal lineage cells to repair tissues. This review aims to summarize the functions of BM-derived-MSCs, and the treatment of intractable diseases such as rheumatoid arthritis (RA) and malignant tumors with IBM-BMT.

Improved Expression of Sirt1 on Thymic Epithelial Cells of SAMP10 after Intrabone Marrow–Bone Marrow Transplantation

Aging is accompanied by various forms of immune dysfunction, leading to an increase in frequency of infections and the development of malignant tumors in mice and humans. Sirt1 has been implicated in processes as varied as metabolism, differentiation, cancer, and the stress response and aging. Senescence-accelerated mice prone 10 (SAMP10) show not only spontaneously occurring brain atrophy, with deficits in learning and memory, but also emotional disorders. We attempted in this study to clarify the deficits and found that the percentage of CD4/TNF-α T-cells in the spleen of 24-week-old (but not 6-week-old) SAMP10 to be significantly reduced. The thymus was significantly lighter, and the percentage of CD4⁺CD8⁺ cells was significantly lower in the 24-week-old SAMP10 than 6-week-old SAMP10. Microarray analyses indicated that genes related to transcription coactivator activity, growth factor activity, hormone activity, cytokine activity, receptor activity, and regulation of the immune system were downregulated in the thymus of 24-week-old SAMP10. Real-time PCR analysis showed that the expression of KGF, Aire, and Sirt1 was decreased on the thymic epithelial cells (TECs) of 24-week-old SAMP10. However, these parameters improved after the mice were treated with intrabone marrow-bone marrow transplantation. This is the first report of age-related changes in immune system dysfunction in 24-week-old SAMP10 and the first to show that dysfunction on the TECs of 24-week-old SAMP10 was modulated by allogeneic bone marrow cells.

Gr-1 Ab administered after bone marrow transplantation plus thymus transplantation suppresses tumor growth by depleting granulocytic myeloid-derived suppressor cells.

It has been shown that allogeneic intra-bone marrow–bone marrow transplantation (IBM-BMT) plus thymus transplantation (TT) is effective in treating recipients with malignant tumors. Although TT increases the percentage of T cells in the early term after BMT, the myeloid-derived suppressor cells (MDSCs) are still the dominant population. We used the Gr-1 Ab to deplete the granulocytic MDSCs (G-MDSCs) in tumor-bearing mice that had received BMT+TT. Two weeks after the BMT, the mice injected with Gr-1 Ab showed smaller tumors than those in the control group. In addition, Gr-1 Ab significantly increased the percentages and numbers of CD4+ and CD8+ T cells, and decreased the percentages and numbers of MDSCs and G-MDSCs. No side effects of the Gr-1 Ab on recipient or donor thymus were observed. These findings indicate that Gr-1 Ab administered after BMT+TT may enhance the effectiveness of tumor suppression.

Stem cell transplantation improves aging-related diseases.

Aging is a complex process of damage accumulation, and has been viewed as experimentally and medically intractable. The number of patients with age-associated diseases such as type 2 diabetes mellitus (T2DM), osteoporosis, Alzheimer's disease (AD), Parkinson's disease, atherosclerosis, and cancer has increased recently. Aging-related diseases are related to a deficiency of the immune system, which results from an aged thymus and bone marrow cells. Intra bone marrow-bone marrow transplantation (IBM-BMT) is a useful method to treat intractable diseases. This review summarizes findings that IBM-BMT can improve and treat aging-related diseases, including T2DM, osteoporosis and AD, in animal models.

Mesenchymal stem cells for inducing tolerance in organ transplantation.

Organ transplantation is useful for treating the end stage of organ failure. The induction of tolerance to the transplanted organ is essential for its long-term survival. Immunologic tolerance can be induced by immunosuppressive agents and mixed chimerism. Mixed chimerism is a state in which both recipient-and donor-derived blood cells remain in the hematopoietic system after allogeneic hematopoietic stem cells have been transplanted. Mesenchymal stem cells (MSCs), and immune cells such as dendritic cells and T-reg cells play an important role in the induction of tolerance. MSCs secrete cytokines, which modulate the immune response. In particular, they upregulate T-reg cell function and thereby induce tolerance. Intra-bone marrow-bone marrow transplantation recruits both donor-derived HSCs and MSCs, inducing persistent donor-specific tolerance without the use of immunosuppressants. In this review, we summarize the use of MSCs to induce tolerance in organ transplantation.

17. Selective localization of bone marrow-derived ramified cells in the brain adjacent to the attachments of choroid plexus

Although the immune system modulates higher functions of the brain under non-inflammatory conditions, how immune cells interact with brain parenchymal cells remains to be determined. Using bone marrow chimeric mice produced by syngeneic intra-bone marrow-bone marrow transplantation (IBM-BMT) with GFP-transgenic mice being as a donor, we examined the distribution, density and differentiation of donor-derived marrow cells in the brain parenchyma 2 weeks and 1, 4 and 8 months after BMT. Marrow-derived cells started to populate discrete brain regions from 1 to 4 months after BMT, exhibited ramified morphology and expressed Iba-1. Most of these discrete regions were adjacent to the attachments of choroid plexus that comprised thinned brain parenchyma consisting of astroglial processes in the narrow channel between the ependyma and pia. These specific portions of astroglial processes expressed fractalkine. In the choroid plexus stroma, not only Iba-1 + myeloid cells but also non-myeloid CXCL12-expressing cells were of bone marrow-origin. Transcripts of fractalkine, CXCL12 and their related molecules such as CX3CR1, ADAM10 and CXCR4 were detected in the tissue consisting of the choroid plexus, the attachments and adjacent brain parenchyma. Thus, bone marrow cells selectively enter the discrete brain regions adjacent to the attachments of choroid plexus and differentiate into ramified myeloid cells. Fractalkine in the attachments of choroid plexus and CXCL12 in the choroid plexus stroma may be involved in these brain–immune interactions.

Prolonged survival in mice with advanced tumors treated with intra-bone marrow-BMT plus fetal thymus transplantation with restoration of T cell functions (P2177)

Abstract Thymic function decreases in line with tumor progression in patients with cancer, resulting in immunodeficiency and a poor prognosis. In the present study, we attempted to restore thymic function by BALB/c (H-2d) syngeneic (Syn) or B6 (H-2b) allogeneic (Allo) bone marrow transplantation (BMT) using intra-bone marrow-bone marrow transplantation (IBM-BMT) plus Syn-, Allo- or C3H (H-2k) 3rd-party fetal thymus transplantation (TT). Although the BALB/c mice with advanced tumors (Meth-A sarcoma; H-2d, &amp;gt;4 cm2) treated with either Syn- or Allo-BMT alone showed a slight improvement in survival compared with non-treated controls, the mice treated with BMT + TT showed a longer survival. The mice treated with Allo-BMT + Allo-TT or 3rd-party TT showed the longest survival. Interestingly, although there was no difference in main tumor size among the BMT groups, lung metastasis was significantly inhibited by Allo-BMT + Allo-TT or 3rd-party TT. Although host thymus was still atrophied, transplanted thymus was well-engrafted. T cell functions increased significantly, whereas number of myeloid suppressor cells and regulatory T cells significantly decreased in these mice. These results suggest that BMT + TT, particularly Allo-BMT + Allo-TT or 3rd-party TT, is most effective in prolonging survival as a result of the restoration of T cell function in hosts with advanced tumors.

CD4+ T Cell–Depleted Lymphocyte Infusion Impairs Neither the Recovery of Recipient Thymus nor the Development of Transplanted Thymus

Thymus transplantation, in conjunction with bone marrow transplantation (BMT), has been attracting attention for the treatment of various diseases. Recently, donor lymphocyte infusion (DLI) has been used as a helpful tool for establishing donor chimerism and preventing a relapse of leukemia/lymphoma. However, the effects of DLI on transplanted and recipient thymuses have not been explored. We therefore performed DLI in the intrabone marrow-BMT + thymus transplantation setting. We have found that DLI leads to derangements in both recipient thymuses and transplanted thymuses; by 2 wk after BMT, we saw a decrease in total cell number, a lower percentage of CD4(+)CD8(+) cells, and the obliteration of the thymic corticomedullary junction. Four weeks later, the thymic impairment became more serious. However, when we depleted the CD4(+) T cells (CD4(-)-DLI), the recipient thymic recovery and transplanted thymic development were significantly restored by the treatment. In addition, there were much greater levels of TNF-α and Fas ligand, and a lower percentage of regulatory T cells in the DLI group than in the CD4(-)-DLI group. These findings indicate that inflammation induced by DLI, especially by CD4(+) T cells, plays a crucial role in the thymic impairment.

Immunomodulatory Properties and Therapeutic Application of Bone Marrow Derived-Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are prototypical adult stem cells, identified as an adherent, fibroblast-like population positive for CD105, CD90 and CD73, and lacking hematopietic markers. MSCs can be isolated from different adult tissues including bone marrow (BM), umbilical cord, skeletal muscle and adipose tissue. MSCs have a potent immunomodulatory function via soluble factors, including PGE2, TGF-β, indoleamine 2,3-dioxygenase (IDO), IL-10, and HGF. Treatment with MSCs can improve type 1 diabetes, liver fibrosis and arthritis via their immunomodulatory function. Intra-bone marrow bone marrow transplantation (IBM-BMT) can replace not only hemopoietic stem cells (HSCs) but also MSCs. IBM-BMT seems to be the best strategy for allogeneic BMT, and may improve aging-related diseases, including type 2 diabetes and osteoporosis. IBM-BMT has also been shown to be the most effective strategy to prevent the rejection of organ allografts. This review summarizes the immunomodulatory properties and therapeutic application of bone marrow derived-MSCs.

Autoimmune Disease Treatment with Stem Cell Transplantation

Autoimmune Diseases (ADs) are diseases in which the immune system mistakenly attacks and destroys selfmolecules due to a disruption of immunologic tolerance to auto-reactive immune cells. The goals of treatments for ADs are to 1) reduce symptoms, 2) control the autoimmune process and 3) maintain the body’s ability to fight disease. Allogenic Hematopoietic Stem Cell (HSC) transplantation has been shown to be a relatively successful treatment for experimental ADs. Intra Bone Marrow-Bone Marrow Transplantation (IBM-BMT) has been proven to be a powerful strategy for allogeneic BMT due to the rapid hemopoietic recovery and the complete restoration of T cell functions even in donor-recipient combinations across MHC barriers. In this review, we summarize the ADs treatable with IBM-BMT.