Successful liver allografts in mice by combination with allogeneic bone marrow transplantation

A novel BMT technique for treatment of various currently intractable diseases

A recently-developed BMT method combines a "Perfusion Method" (PM) for collecting bone marrow cells (BMCs) with the Intra-Bone Marrow (IBM) injection of BMCs (IBM-BMT). As distinct from the conventional aspiration method (AM), the PM allows rapid (within 1 h) collection of BMCs without T cell contamination (T cells < 10%). Therefore, no GvHD occurs. Moreover, the burden on donors, such as back pain, bleeding and infection, can be reduced. Full chimerism can be achieved even with only mild conditioning regimens if IBM-BMT is carried out, since IBM-BMT replaces not only the recipient's hemopoietic stem cells (HSCs) but also mesenchymal stem cells (MSCs) with donor-derived HSCs and MSCs. Using this method, we show that most currently intractable diseases are HSC or MSC disorders, and that this novel strategy (PM + IBM-BMT) can be used to treat various otherwise intractable diseases (including autoimmune diseases and age-associated diseases). We believe that the development of this technique will herald a revolution in the field of BMT, regeneration medicine and also organ transplantation.

Mesenchymal stem cells protect islets from hypoxia/reoxygenation-induced injury

Hypoxia/reoxygenation (H/R)-induced injury is the key factor associated with islet graft dysfunction. This study aims to examine the effect of mesenchymal stem cells (MSCs) on islet survival and insulin secretion under H/R conditions. Islets from rats were isolated, purified, cultured with or without MSCs, and exposed to hypoxia (O(2) ≤ 1%) for 8 h and reoxygenation for 24 and 48 h, respectively. Islet function was evaluated by measuring basal and glucose-stimulated insulin secretion (GSIS). Apoptotic islet cells were quantified using Annexin V-FITC. Anti-apoptotic effects were confirmed by mRNA expression analysis of hypoxia-resistant molecules, HIF-1α, HO-1, and COX-2, using semi-quantitative retrieval polymerase chain reaction (RT-PCR). Insulin expression in the implanted islets was detected by immunohistological analysis. The main results show that the stimulation index (SI) of GSIS was maintained at higher levels in islets co-cultured with MSCs. The MSCs protected the islets from H/R-induced injury by decreasing the apoptotic cell ratio and increasing HIF-1α, HO-1, and COX-2 mRNA expression. Seven days after islet transplantation, insulin expression in the MSC-islets group significantly differed from that of the islets-alone group. We proposed that MSCs could promote anti-apoptotic gene expression by enhancing their resistance to H/R-induced apoptosis and dysfunction. This study provides an experimental basis for therapeutic strategies based on enhancing islet function.

Replacement of liver parenchyma in analbuminemic rats with allogenic hepatocytes is facilitated by intrabone marrow-bone marrow transplantation

Although hepatocyte transplantation (HCTx) is expected to become a useful therapy for human liver diseases, allogenic hepatocytes still tend to be rejected within a short period due to host immunosurveillance. In the present study, we investigated the effect of prior bone marrow transplantation (BMTx) for the engraftment of allogenic hepatocytes using the analbuminemic rat transplantation model. The hepatocytes of Lewis (LEW) rats were not accepted in the liver of retrorsine (RS)/partial hepatectomy (PH)-treated analbuminemic F344 (F344-alb) rats, which express the disparate major histocompatibility complex (MHC) against that of LEW rats. Prior BMTx with the LEW bone marrow cells (BMCs) after sublethal irradiation achieved acceptance and repopulation of LEW hepatocytes in the liver of the RS/PH-treated F344-alb rats, associated with elevation of serum albumin. The replacement of hepatic parenchyma with albumin positive (Alb(+)) donor hepatocytes and elevation of serum albumin levels were dependent on the bone marrow reconstitution by donor BMCs, which was more efficiently achieved by intrabone marrow (IBM)-BMTx than by intravenous (IV)-BMTx. Our results demonstrate that efficient bone marrow reconstitution by IBM-BMTx enables the replacement of the hepatic parenchyma with allogenic hepatocytes in RS/PH-treated analbuminemic rats without immunosuppressants.

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.

IL-2 pathway blocking in combination with anti-CD154 synergistically establishes mixed macrochimerism with limited dose of bone marrow cells and prolongs skin graft survival in mice

To facilitate the establishment of mixed chimerism with limited dose of bone marrow (BM) cells, and to achieve tolerance in skin graft model, combined blocking of costimulatory pathway and IL-2 pathway was used in minimally myeloablative model using busulfan. BM cells (2.5x10(7)) of BALB/c were injected into C57BL/6 mice at day 0 with full thickness skin graft after single dose injection of busulfan (25 mg/kg) on day-1. Recipients were grouped and injected the anti-CD154, CTLA4-Ig, anti-IL-2R at days 0, 2, 4, and 6 according to protocol. Mixed macrochimerism were induced in groups treated with anti-CD154+anti-CTLA4-Ig, anti-CD154+anti-IL-2R, and anti-CD154+anti-CTLA4 Ig+anti-IL-2R. Three groups having chimerism enjoyed prolonged graft survival more than 6 months. Superantigen deletion study revealed deletion of alloreactive T cells in combined blockade treated groups. In graft versus host disease model using CFSE staining, CD4+ T cell and CD8+ T cell proliferation were reduced in groups treated with CTLA4-Ig or anti-IL-2R or both in combination with anti-CD154. However, anti-IL-2R was not so strong as CTLA4-Ig in terms of inhibition of T cell proliferation. In conclusion, IL-2 pathway blocking combined with anti-CD154 can establish macrochimerism with limited dose of BM transplantation and induce specific tolerance to allograft.

Synergistic effects of injection of bone marrow cells into both portal vein and bone marrow on tolerance induction in transplantation of allogeneic pancreatic islets

We have established a new method for allogeneic pancreatic islet (PI) transplantation: relatively low doses of irradiation followed by simultaneous transplantation of PIs and bone marrow cells (BMCs) via the portal vein (PV). In the present study, we have compared this method with intra-bone marrow (IBM)-bone marrow transplantation (BMT), and with a combination of both methods. Streptozotocin (STZ)-induced diabetic-recipient rats, Fischer 344 (F344, RT1A(l), RT1B(l)), were irradiated 1 day before transplantation. PIs of Brown Norway rats (BN, RT1A(n), RT1B(n)) were transplanted into the liver of the diabetic F344 rats via the PV. BMCs from BN rats were injected into the recipients' bone marrow (IBM), PV or intravenously (IV) or by a simultaneous combination of PV plus IBM (PV+IBM). We compared graft survival among the groups of '9 Gy+IBM'(10/10 accepted), '9 Gy+PV'(7/10 accepted), '9 Gy+IV'(0/7 accepted), '9 Gy+PV+IBM'(8/8 accepted), '8.5 Gy+IBM'(4/9 accepted), '8.5 Gy+PV'(0/7 accepted), '8.5 Gy+IV'(0/7 accepted), '8.5 Gy+PV+IBM'(9/12 accepted), '8 Gy+IBM'(2/10 accepted) and '8 Gy+PV+IBM'(2/8 accepted). As we reported previously, PV-BMT is more effective in inducing the acceptance of allogeneic PIs than IV-BMT. However, IBM-BMT requires less pretreatment than PV-BMT. (PV+IBM)-BMT was found to be the most effective in inducing the acceptance of allogeneic PIs. These results suggest that allogeneic PI-transplantation in conjunction with (PV+IBM)-BMT could become a viable strategy.

Treatment of streptozotocin-induced diabetes mellitus in rats by transplantation of islet cells from two major histocompatibility complex disparate rats in combination with intra bone marrow injection of allogeneic bone marrow cells

BACKGROUND

We have established a new method for the transplantation of allogeneic pancreatic islets obtained from two different rat strains in combination with a newly developed bone marrow transplantation (BMT) method in which bone marrow cells (BMCs) are directly injected into the bone marrow cavity (intra bone marrow BMT [IBM-BMT]).

METHODS

Streptozotocin-induced diabetic Brown Norway (BN: RT1A(n)) rats were injected with fludarabine, irradiated with 5.0 Gy x 2, and BMCs from two allogeneic rat strains, Fischer 344 (F344: RT1A(1)) and PVG (PVG: RT1A(c)), were then directly injected into the bone marrow cavity (IBM-BMT). Simultaneously, approximately 600 pancreatic islets (PIs) from F344 and PVG rats were mixed and transplanted into the liver by way of the portal vein.

RESULTS

All the recipients thus treated showed normoglycemia 30 days after the treatment. Hematolymphoid cells were completely reconstituted with the two donor-type cells, and immunologic tolerance to F344 and PVG major histocompatibility complex (MHC) determinants were induced.

CONCLUSIONS

The transplantation of PIs from two MHC-disparate donors was completely achieved in combination with IBM-BMT, resulting in the improvement of blood glucose levels and the amelioration of diabetes mellitus.

A novel strategy for allogeneic stem cell transplantation: perfusion method plus intra–bone marrow injection of stem cells

Using long bones of cynomolgus monkeys, we have recently developed a new "Perfusion Method (PM)" for harvesting bone marrow cells (BMCs) while minimizing the contamination of BMCs with T cells from the peripheral blood. When thus collected BMCs, which contain not only pluripotent hemopoietic stem cells (P-HSCs) but also mesenchymal stem cells (MSCs), are directly injected into the bone marrow cavity of recipients (intra-bone marrow BMT: "IBM-BMT"), the donor-derived hemopoietic cells quickly recover even when the radiation doses used as the conditioning regimen are reduced. Recipient mice, rats, and even monkeys show neither graft-vs-host disease (GVHD) nor graft failure. In this article, we discuss why this new method (PM+IBM-BMT) may become a valuable strategy for allogeneic stem cell (both P-HSC and MSC) transplantation.

New strategies for allogeneic BMT

In humans, the success rate of BMT across major histocompatibility complex (MHC) barriers is lowered by graft-versus-host disease (GvHD), graft rejection and incomplete T-cell recovery. To prevent GvHD, we attempted to minimize the contamination of bone marrow cells (BMCs) with T cells from the peripheral blood when donor BMCs were collected, finally establishing a new 'Perfusion Method' using cynomolgus monkeys. There was significantly less contamination of BMCs with T cells in this method (<6%) than in the conventional 'Aspiration Method' (>20%) consisting of multiple aspirations of BMCs from the iliac crest. Using radio-sensitive and chimerism-resistant MRL/lpr mice, we also established a new method for allogeneic (allo) BMT and organ allografts. In this method, whole BMCs, containing a small number of T cells and mesenchymal stem cells (MSCs), were directly injected into the bone marrow cavity (intrabone marrow [IBM]-BMT). MRL/lpr mice treated with IBM-BMT survived more than 2 years without showing the symptoms of autoimmune diseases. IBM-BMT thus has several advantages: (i) no GvHD develops even if T cells are not depleted from BMCs; (ii) no graft failure occurs even if the dose of radiation as the conditioning regimen for allo BMT is reduced to 5Gy x 2; (iii) hemopoietic recovery is rapid; and (iv) the restoration of T-cell functions is quick and complete even in donor-recipient combinations across MHC barriers. We believe that these strategies for allo BMT and organ allografts herald a new era in transplantation, and that they would be helpful in allogeneic HSCT of autoimmune diseases.

Treatment of autoimmune diseases in mice by a new method for allogeneic bone marrow transplantation

Remarkable advances have been made in bone marrow transplantation (BMT), which has become a powerful strategy for the treatment of leukemia, aplastic anemia, congenital immunodeficiency, and also autoimmune disease. Using various animal models, allogeneic (allo) BMT has been found to be useful in the treatment of various autoimmune diseases. In MRL/lpr mice, which are radiosensitive (<8.5 Gy) and are an animal model for autoimmune diseases, conventional BMT resulted in only transient effects; the manifestations of the autoimmune diseases recurred 3 months after BMT. Using MRL/lpr mice, we have very recently established a new strategy for allo BMT. We injected bone marrow cells (BMC) directly into the bone marrow cavity (intrabone marrow [IBM] injection) of recipients that had received fractionated irradiation. This 'IBM-BMT' was found to be effective in treating autoimmune diseases in radiation-sensitive and chimeric-resistant MRL/lpr mice. In addition, this strategy was found to be applicable for the transplantation of organs. We believe that these strategies for BMT and organ transplantation herald a new era in transplantation.

New strategies for BMT, organ transplantation, and regeneration therapy

Bone marrow transplantation (BMT) is becoming a powerful strategy for the treatment of hematologic disorders, congenital immunodeficiencies, metabolic disorders and also autoimmune diseases. We have previously found using various animal models for spontaneous autoimmune diseases, that allogeneic bone marrow transplantation (allo BMT) can be used to prevent and treat various autoimmune diseases. In addition, we have found that autoimmune diseases are stem cell disorders. However, in MRL/lpr mice, which are radiosensitive (<8.5 Gy), we found that conventional BMT had only a transient effect on autoimmune diseases, which were found to recur. Therefore, we concentrated on discovering new strategies to prevent and treat autoimmune diseases in the radiosensitive and chimeric-resistant MRL/lpr mouse. Using MRL/lpr mice, we established a new method for allo BMT. In this method, whole bone marrow cells (BMCs), containing a small number of T cells and mesenchymal stem cells (MSCs), were directly injected into the bone marrow cavity (intra-bone marrow [IBM]-BMT). MRL/lpr mice treated with IBM-BMT survived more than 2 years without showing the symptoms of autoimmune diseases. To apply this BMT method to humans, we have also established a new method for BMC harvesting using cynomolgus monkeys. In this method, BMCs are harvested from the long bones using a "Perfusion Method" (PM) and the whole BMCs (including MSCs) are then injected directly into the IBM. We believe that this new method will become a powerful strategy for the treatment of various intractable diseases, including age-associated diseases such as osteoporosis.

Induction of tolerance in autoimmune diseases by hematopoietic stem cell transplantation: getting closer to a cure?

Hematopoietic stem cells (HSCs) are the earliest cells of the immune system, giving rise to B and T lymphocytes, monocytes, tissue macrophages, and dendritic cells. In animal models, adoptive transfer of HSCs, depending on circumstances, may cause, prevent, or cure autoimmune diseases. Clinical trials have reported early remission of otherwise refractory autoimmune disorders after either autologous or allogeneic hematopoietic stem cell transplantation (HSCT). By percentage of transplantations performed, autoimmune diseases are the most rapidly expanding indication for stem cell transplantation. Although numerous editorials or commentaries have been previously published, no prior review has focused on the immunology of transplantation tolerance or development of phase 3 autoimmune HSCT trials. Results from current trials suggest that mobilization of HSCs, conditioning regimen, eligibility and exclusion criteria, toxicity, outcome, source of stem cells, and posttransplantation follow-up need to be disease specific. HSCT-induced remission of an autoimmune disease allows for a prospective analysis of events involved in immune tolerance not available in cross-sectional studies.

New strategies for BMT and organ transplantation

Bone marrow transplantation (BMT) is now one of the most powerful strategies for the treatment of hematologic disorders (leukemia, aplastic anemia, etc), congenital immunodeficiencies, metabolic disorders, and also autoimmune diseases. Using various autoimmune-prone mice, we have previously shown that conventional allogeneic (allo) BMT can be used to treat a range of autoimmune diseases. We have very recently established new strategies for BMT and organ grafts. For BMT, to minimize the contamination of BMCs with T cells from the peripheral blood, we developed, using cynomolgus monkeys, a "Perfusion Method" to replace the conventional aspiration method for collecting bone marrow cells (BMCs). We injected the BMCs collected this way directly into the bone marrow cavity of recipients that had received fractionated irradiation (intra-bone marrow [IBM] injection). This "IBM-BMT" was found to be effective in treating autoimmune diseases in radiation-sensitive and chimeric-resistant MRL/lpr mice. in addition, this strategy was found to be applicable for the transplantation of organs, such as the skin and pancreas islets in mice and rats. We believe that these strategies for BMT and organ transplantation herald a new era in transplantation.

Treatment of streptozotocin-induced diabetes mellitus by transplantation of islet cells plus bone marrow cells via portal vein in rats

BACKGROUND

We have established a new method for the transplantation of allogeneic pancreatic islets (PIs) using sublethal irradiation (9 Gy) plus simultaneous transplantation of PIs and bone marrow cells (BMCs) via the portal vein (PV) followed by intravenous (i.v.) injection of donor BMCs (9 Gy + PV + i.v.).

METHODS

Approximately 600 PIs of Brown Norway (BN: RT1An, RT1Bn) rats were transplanted into the liver of streptozotocin-induced diabetic Fischer 344 (F344: RT1Al, RT1Bl) rats via the PV. BMCs (3x108) of BN rats were injected via the PV or i.v. into the recipients simultaneously. In some groups, additional i.v. injections of BMCs from BN rats were given 5 days after the PI transplantation.

RESULTS

All the recipients (10 of 10) in the 9 Gy + PV + i.v. group showed normoglycemia for more than 1 year, whereas PIs were rejected within 30 days after transplantation in the group of 9 Gy + i.v. + i.v.

CONCLUSIONS

These results suggest that simultaneous transplantation of PIs and BMCs via the PV is effective in inducing persistent tolerance.

New method for thyroid transplantation across major histocompatibility complex barriers using allogeneic bone marrow transplantation

BACKGROUND

It has been shown that allogeneic bone marrow transplantation (BMT) after lethal irradiation elicits donor-specific tolerance for organ or tissue transplantation across major histocompatibility complex (MHC) barriers. Recently, we have demonstrated that the portal venous (p.v.) administration of donor bone marrow cells (BMCs) elicits donor-specific tolerance across MHC barriers by only two administrations of an immunosuppressant (CsA or FK-506). In our study, using the central and intrahepatic tolerance-inducing system, we have established a new method for thyroid transplantation with BMT that would be more applicable to humans.

METHODS

In addition to sublethal (6-5 Gy) irradiation, recipient B6 (H-2b) mice received injections i.p. with the myeloablative drug busulfan (BU) on day -2 to provide a sufficient "space" for the donor hematopoietic cells to expand in the recipients. To induce the intrahepatic tolerance, donor BALB/c (H-2d) BMCs were treated with neuraminidase (Neu), which enhances the trapping of i.v. injected BMCs in the liver. After the injection of Neu-treated BMCs, the thyroid organs from the BALB/c mice were engrafted under the renal capsules.

RESULTS

A 90% graft survival rate was obtained over 100 days by a combination of BU administration, 6 Gy irradiation, and i.v. injection of Neu-treated BMCs [BU+6 Gy+(Neu) i.v.], and a 70% graft survival rate was obtained by [BU+5 Gy+(Neu) i.v.]. However, the graft survival rate significantly decreased when either the BU or Neu treatment was omitted. T cells collected from the tolerant recipients suppressed the proliferative responses to donor alloantigens.

CONCLUSIONS

Using both BU and Neu treatments, we have succeeded in inducing long-term tolerance and preventing the rejection of thyroid allografts by the single-day protocol.

A novel strategy for organ allografts using sublethal (7 Gy) irradiation followed by injection of donor bone marrow cells via portal vein

A new strategy for organ allografts that does not require recourse to immunosuppressants is established in mice. The strategy includes sublethal (7 Gy) irradiation followed by the injection of donor bone marrow cells (BMCs) via the portal vein (P.V.) and organ allografts 1 day after irradiation. Irradiation doses (< or =7 Gy) are found to allow the recipients to survive without the need to reconstitute the BMCs, as the recipient hematolymphoid cells can gradually recover. One hundred percent of recipients irradiated with 7 Gy followed by either P.V. or i.v. injection of donor BMCs accept organ allografts (the skin, pancreas, and adrenal glands) for more than 1 year. However, organ allograft survival rates decrease when irradiation doses are reduced; the skin graft survival rate of mice treated with 6.5 Gy and P.V. injection of BMCs is 79%, whereas that of mice treated with 6.5 Gy and i.v. injection is 50%, indicating that the P.V. injection of BMCs induces persistent tolerance more effectively than the i.v. injection. H-2 typing reveals that almost all the hematolymphoid cells (>98%) in the peripheral blood and hematolymphoid organs are donor-derived even 1 year after the treatment (7 Gy and P.V.). The T cells are tolerant to both donor-type and host-type MHC determinants. The major mechanism underlying the persistent tolerance induced by this strategy seems to be because of clonal deletion. This simple and safe strategy would be of great advantage for human organ transplantation.

Treatment of autoimmune diseases by hematopoietic stem cell transplantation

Remarkable advances have been made in bone marrow transplantation (BMT), which now has become a powerful strategy for the treatment of leukemia, aplastic anemia, congenital immunodeficiency disorders, and autoimmune diseases. Using various animal models, allogeneic BMT has been found to be useful in the treatment of autoimmune diseases. In MRL/lpr mice, which are radiosensitive (<8.5 Gy) and are an animal model for autoimmune disorders, conventional BMT resulted in only transient effects; the manifestations of the autoimmune diseases recurred 3 months after BMT. However, the combination of BMT plus bone grafts (to recruit donor stromal cells) was capable of preventing the recurrence of autoimmune diseases in MRL/lpr mice. This strategy was found to be ineffective in the treatment of MRL/lpr mice that had developed autoimmune diseases, because these mice were more sensitive to the effects of radiation after the onset of lupus nephritis due to uremic enterocolitis. We have recently discovered a safer strategy for treatment of autoimmune diseases, which includes fractionated irradiation (5.5 Gy x 2) (day -1) followed by portal venous injection (day 0) plus intravenous injection (day 5) of donor unfractionated bone marrow cells. We successfully treated autoimmune diseases in MRL/lpr mice using this strategy; 100% of MRL/lpr mice treated in this fashion survive >1 year after treatment. We identified the mechanisms underlying the components of this approach and have found that stromal cells play a crucial role in successful BMT. In this review, the conditions essential for successful allogeneic BMT are discussed.

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%).

Acceptance of skin allografts in pigs by portal venous injection of donor bone marrow cells

OBJECTIVE

To confirm in pigs whether a new method for organ allografts, originally established in mice by the authors, might be applicable to humans.

SUMMARY BACKGROUND DATA

The authors recently established a new method for organ allografts in mice that includes the injection of donor bone marrow cells (BMCs) using the portal vein (PV), followed by the administration of cyclosporin A (CsA) on days 2 and 5, and the intravenous injection of BMCs on day 5. In the present study, they modify this method (a single-day protocol) and apply it to pigs.

METHODS

Allogeneic BMCs of donor pigs were injected using the PV (a superior mesenteric vein). The skin grafting was carried out on the day of the PV injection. The recipient pigs received donor grafts, autologous grafts, and third-party grafts at the same time. In addition, an open wound was made as the epithelized control. Full-thickness skin grafts were harvested from the dorsal wall of the donors. CsA (10 mg/kg) was injected intramuscularly into recipient pigs on days 2 and 5 after the PV injection.

RESULTS

One hundred percent of skin grafts survived for >300 days when donor BMCs were injected using the PV (n = 6). However, the skin grafts of the three pigs that had received BMCs using the intravenous route were rejected within 3 to 4 weeks after transplantation. The third-party skin grafts showed necrotic changes on day 21 after transplantation.

CONCLUSIONS

One hundred percent of skin allografts can be obtained, even in pigs, by injecting donor BMCs using the PV, carrying out skin allografts, and administering CsA on days 2 and 5. This single-day protocol would be of great advantage for human organ transplantation.

A strategy for organ allografts without using immunosuppressants or irradiation

A strategy to achieve regular and long lasting organ and tissue allografts without using immunosuppressants and/or irradiation has been established for mice. One hundred percent of skin allografts can be induced to survive >350 days after transplantation if spleen cells from the same donors are first injected into the portal vein of the recipients. The mechanisms underlying this long-term tolerance induction can be described as follows: (i) donor T cells from the spleen of the donor facilitate the acceptance of the allogeneic engraftment, (ii) donor-specific anergy is induced in the cytotoxic T-lymphocytes of the recipients, (iii) T helper type 2 cells become the dominant T cells in the recipients that are accepting the skin transplants, and (iv) a lasting chimerism (microchimerism) is established in these recipients. This strategy, perhaps with minor modifications, might permit one also to overcome major barriers to organ allografting in humans. If this were the case, it could represent production of long lasting immunologic tolerance without need for irradiation or cytotoxic chemo-preparative regimen and as such could greatly facilitate allotransplantation free of episodes of chronic or acute rejection or toxic and damaging preparatory regimens.

Tolerance of allogeneic heart grafts in mice simultaneously reconstituted with purified allogeneic hematopoietic stem cells

BACKGROUND

Animals reconstituted with allogeneic whole bone marrow (WBM) are often tolerant of donor-specific solid organ grafts. Clinical application of bone marrow transplantation in solid organ transplantation has been limited, however, principally by graft-versus-host disease. We previously demonstrated that hematopoietic stem cells (HSCs) reconstitute lethally irradiated allogeneic mice without producing graft-versus-host disease. The purpose of this study was to determine whether tolerance to solid organ grafts could be induced in mice reconstituted with HSCs.

METHODS

BALB/c mice were lethally irradiated and reconstituted with allogeneic C57BL/Ka, Thy-1.1 WBM or HSCs. An isolated group was given a limited number of HSCs (250 cells) and a subpopulation of allogeneic cells known to facilitate HSC engraftment (facilitators). C57BL/Ka, Thy-1.1 neonatal heart grafts were placed in reconstituted animals either at the time of hematopoietic transplant or 35 days later. Third-party C3H grafts were placed over 2 months after hematopoietic reconstitution. Tolerance was defined as the persistence of cardiac contraction for the duration of evaluation (125-270 days).

RESULTS

All surviving mice that were reconstituted with C57BL/Ka, Thy-1.1 HSCs, WBM, or HSCs and facilitators were tolerant of C57BL/Ka grafts long-term. Third-party C3H grafts placed in reconstituted animals were rejected by day 12, whereas those placed in unmanipulated mice were rejected by day 9.

CONCLUSION

These data indicate that tolerance to concurrently or subsequently placed solid organ grafts can be reliably achieved with limited numbers of purified HSCs in a model where immunocompetence to third-party major histocompatibility complex antigens is delayed but intact.

Intractable diseases and bone marrow transplantation

Intractable diseases are defined as diseases of unknown etiopathogenesis, and for which therapeutic strategies remain to be established. They are therefore likely to cause various sequelae. Of the 86 intractable diseases recognized by the Ministry of Health and Welfare of Japan, half are thought to be curable by bone marrow transplantation (BMT). This report shows which diseases are curable by BMT and provides evidence that autoimmune diseases are stem cell disorders.

Long-term observations of autoimmune-prone mice treated for autoimmune disease by allogeneic bone marrow transplantation

Long-term effects of allogeneic bone marrow transplantation (ABMT) across major histocompatibility complex barriers were studied in (NZB x NZW)F1 (B/W), BXSB, and MRL/Mr-lpr-lpr (MRL/lpr) mice with established autoimmune disease at the time of ABMT. In the BXSB or B/W mice, ABMT cured all aspects of autoimmune disease. Glomerular damage, revealed by histological study was dramatically improved. Serological abnormalities and immunologic functions also were normalized. Correction of autoimmune disease and advanced renal disease in BXSB and B/W mice regularly lasted greater than 5-6 mo and even 1 yr after ABMT. In the MRL/lpr mice, however, autoimmune and renal disease at first improved but then recurred after ABMT, apparently because of intolerance of mice for high doses of irradiation and a high degree of resistance of recipient stem cells to irradiation. In this model, H-2 typing revealed that by the time of relapse, immunocompetent cells of the chimeric mice had been replaced by host (MRL/lpr; H-2k) cells. B220+ Ly-1+ cells, present in increased numbers in untreated MRL/lpr mice, initially returned to normal levels after ABMT but then reappeared in the MRL/lpr mice that had received marrow from donors having few such lymphocytes. Thus, our results show that MRL/lpr mice possess abnormal radioresistant stem cells and provide impressive evidence that the origin of autoimmune diseases in this strain, as in the several other strains studied, residues in abnormalities present in stem cells.

Long-lasting skin allograft tolerance in adult mice induced across fully allogeneic (multimajor H-2 plus multiminor histocompatibility) antigen barriers by a tolerance-inducing method using cyclophosphamide

A new method of cyclophosphamide (CP)-induced skin allograft tolerance in mice that can regularly overcome fully allogeneic (major H-2 plus non-H-2) antigen barriers in mice has been established. The components of the method are intravenous or intraperitoneal administration of 50-100 micrograms of anti-Thy-1.2 mAb on day -1, intravenous injection of 90 x 10(6) allogeneic spleen cells mixed with 30 x 10(6) allogeneic bone marrow cells from the same donor on day 0, and intraperitoneal injection of 200 mg/kg CP on day 2. In each of four fully allogeneic donor----recipient combinations, including C3H/HeJ (C3H; H-2k)----C57BL/6J(B6; H-2b), B6----C3H, BALB/cByJ (BALB; H-2d)----B6, and BALB----C3H, long-lasting survival of skin allografts was induced in most of the recipient mice. The specific tolerant state induced was dependent on the doses of the antibody and bone marrow cells used. The optimal timing of CP treatment to induce tolerance was found to be 1-3 d after the stimulating cell injection. Treatment with the anti-Thy-1.2 antibody together with CP on day 2 after the cell injection on day 0 also induced profound tolerance. In the B6 mice made tolerant of C3H with antibody, C3H spleen cells plus C3H bone marrow cells, and then CP, a minimal degree of stable mixed chimerism was established and the antitolerogen (C3H) immune responses examined here, including delayed footpad reaction (DFR), CTL activity, and capacity for antibody production against donor-strain antigens were abrogated in a tolerogen-specific manner. From cell transfer experiments, the mechanism of tolerance could be largely attributed to reduction of effector T cells reactive against the tolerogen, and strong suppressive influences that might prolong skin allograft survival directly were not detected in the tolerant mice. Moreover, pretreatment with anti-Thy-1.2 antibody or anti-L3T4 (CD4) antibody was more effective than pretreatment with anti-Lyt-1 (CD5) antibody or anti-Lyt-2 (CD8) antibody as an initial step in tolerance induction. These results suggest that permanent tolerance to fully allogeneic skin grafts may be induced because antibody given before the stimulating cell injection reduces the number of reactive T cells in the recipient mice. This antibody treatment may facilitate an antigen-stimulated destruction of responding and thus proliferating cells with CP by preventing a possibly less proliferative, more rapid maturation of reactive T cells or by destroying residual effector T cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Successful pancreatic allografts in combination with bone marrow transplantation in mice

We have established a new method for pancreatic allografts in mice by combining pancreatic transplantation with allogeneic bone marrow transplantation. In this approach, we first transplanted bone marrow to induce tolerance to both donor-type and host-type major histocompatibility complex (MHC) determinants. Pancreatic tissue from the same mouse strain as bone marrow donor was then grafted under the renal capsule. Acceptance of the grafts was confirmed by histopathological and immunohistochemical techniques. BALB/c mice reconstituted with C57BL/6J bone marrow cells accepted pancreatic tissue from both bone marrow donor (C57BL/6J)-type and host (BALB/c)-type mice. An immunohistochemical study revealed the presence of functional islets under the renal capsules. Assays for both mixed lymphocyte reaction (MLR) and induction of cytotoxic T lymphocytes indicated that the newly developed T cells are tolerant of both donor (stem cell)-type and host-type MHC determinants. By contrast, the T cells of these chimeras showed a significant responsiveness to third party MHC determinants. These findings suggest that pancreatic allografts combined with bone marrow transplantation may become a viable strategy for the treatment of patients with diabetes or patients who have undergone pancreatectomy.

Treatment of type 1 diabetes mellitus in non-obese diabetic mice by transplantation of allogeneic bone marrow and pancreatic tissue

Non-obese diabetic (NOD) mice provide a model for type 1 diabetes mellitus. We previously showed that allogeneic bone marrow transplantation (ABMT) can prevent and treat insulitis and overt diabetes in NOD mice. However, ABMT alone could not be used to treat overt diabetes in NOD mice whose islets had been completely destroyed. To provide insulin-producing cells, pancreatic tissue from newborn mice was grafted under the renal capsules in combination with ABMT. The aims of concomitant ABMT are as follows. (i) It induces immunological tolerance to the donor-type major histocompatibility complex determinants and permits the host to accept subsequent pancreatic allografts from the bone marrow donor. (ii) ABMT replaces abnormal stem cells with normal stem cells. After transplantation of bone marrow plus newborn pancreas, NOD mice showed reduction of the glycosuria and a normal response in the glucose-tolerance test. Immunohistological study revealed the presence of clustered insulin-containing beta cells in the grafted pancreatic transplants. ABMT may become a viable treatment of established type 1 diabetes mellitus in humans.

Bone marrow transplantation for immunodeficiency diseases

Allogeneic bone marrow transplantation (BMT) was applied in 1968 to treat severe combined immunodeficiency disease (SCID). Almost simultaneously, marrow from an MHC-matched donor corrected the immunological deficiency of a patient with Wiscott-Aldrich Syndrome (WAS). In the first successful treatment of X-linked SCID the match was imperfect and, although SCID was cured, a graft vs. host reaction caused pancytopenia. A second BMT from the same donor successfully treated a complicating aplastic anemia. Subsequently, it has been possible to cure most patients with SCID who are in reasonably good condition at the time of BMT without other manipulation if a matched sibling donor is available. Successes are reported from Holland, France, Italy, England, Scandinavia, Japan, Germany, and from many centers in the United States. Similarly, BMT is used to correct SCID due to adenosine deaminase (ADA) deficiency or nucleoside phosphorylase (NP) deficiency, which underlie two forms of SCID. Bone marrow transplantation using HLA-matched sibling donors can now treat, successfully, at least eight genetically separable forms of SCID. Highly lethal defects of phagocytic function (including LFA-1, MO-1, CR-3 deficiencies, IL-2 and IL-1 receptor deficiencies), defects of killing after phagocytosis (as in chronic granulomatous disease, WAS, and Kostmann's Syndrome), and certain inborn errors of metabolism can be cured by BMT.(ABSTRACT TRUNCATED AT 250 WORDS)