A New Concept of Stem Cell Disorders and Their New Therapy

Bone Marrow Stromal Cells for Repair of the Spinal Cord: Towards Clinical Application

Stem cells have been recognized and intensively studied for their potential use in restorative approaches for degenerative diseases and traumatic injuries. In the central nervous system (CNS), stem cell-based strategies have been proposed to replace lost neurons in degenerative diseases such as Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis (Lou Gehrig's disease), or to replace lost oligodendrocytes in demyelinating diseases such as multiple sclerosis. Stem cells have also been implicated in repair of the adult spinal cord. An impact to the spinal cord results in immediate damage to tissue including blood vessels, causing loss of neurons, astrocytes, and oligodendrocytes. In time, more tissue nearby or away from the injury site is lost due to secondary injury. In case of relatively minor damage to the cord some return of function can be observed, but in most cases the neurological loss is permanent. This review will focus on in vitro and in vivo studies on the use of bone marrow stromal cells (BMSCs), a heterogeneous cell population that includes mesenchymal stem cells, for repair of the spinal cord in experimental injury models and their potential for human application. To optimally benefit from BMSCs for repair of the spinal cord it is imperative to develop in vitro techniques that will generate the desired cell type and/or a large enough number for in vivo transplantation approaches. We will also assess the potential and possible pitfalls for use of BMSCs in humans and ongoing clinical trials.

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.

Human umbilical cord blood-derived stromal cells prevent graft-versus-host disease in mice following haplo-identical stem cell transplantation

BACKGROUND AIMS

Human umbilical cord blood-derived stromal cells (hUCBDSC) comprise a novel population of CD34(+) cells that has been isolated in our laboratory. They have been shown previously not only to be non-immunogenic but also to exert immunosuppressive effects on xenogenic T cells in vitro. This study investigated the role of hUCBDSC in immunomodulation in an acute graft-versus-host disease (GvHD) mouse model after haplo-identical stem cell transplantation.

METHODS

Acute GvHD was induced in recipient (B6 × BALB/c)F(1) mice by irradiation (750 cGy) followed by infusion of bone marrow cells and splenocytes from donor C57BL/6 mice. hUCBDSC were co-transplanted in the experimental group. The survival time, body weight and clinical and histopathologic scores were recorded after transplantation. The expression of surface markers [major histocompatibility complex (MHC) I, MHC II, CD80 and CD86] on CD11c(+) dendritic cells (DC), and the percentage of CD4(+) regulatory T cells (Treg), in the spleens of recipient mice were examined by flow cytometry.

RESULTS

The survival time was significantly prolonged, and the clinical and histopathologic scores were reduced in mice co-transplanted with hUCBDSC. The expression levels of the surface markers on DC were significantly lower in mice transplanted with hUCBDSC compared with those without. The proportion of CD4(+) Treg in the spleen was also increased in mice transplanted with hUCBDSC.

CONCLUSIONS

These results from a GvHD mouse model are in agreement with previous in vitro findings, suggesting that hUCBDSC possess immunosuppressive properties and may act via influencing DC and CD4(+) Treg.

Transformation potential of bone marrow stromal cells into undifferentiated high-grade pleomorphic sarcoma

PURPOSE

Bone marrow adherent cells contain conventional bone marrow stromal cells and mesenchymal stem cells and these cells constitute the hematopoietic microenvironment. Mesenchymal stem cells have the capacity to give rise to multiple mesenchymal lineage cells and even ectodermal lineage cells. In the present study, we investigated what types of tumor cells are inducible from BM adherent cells by chemical carcinogens.

METHODS

Bone marrow cells from neonatal C3H/HeN mice were collected within 24 h after birth and then cultured. Four days later, bone marrow adherent cells were obtained and the cells were treated with 3-methylcholanthrene.

RESULTS

By this treatment, some transformed clones consisting of large spindle cells were obtained. The transformed cells were highly positive for CD44 and were positive for Sca-1, CD49d and CD106, whereas the cells were negative for hematolymphoid markers. The cell clones had the ability to support hematopoiesis in vitro. These results indicate that the transformed cell lines have the characteristics of BM stromal cells/mesenchymal stem cells. Moreover, during culture of the transformed cells, spontaneous bone nodule formation was observed. When the transformed cells were inoculated into immunodeficient mice subcutaneously, the neoplasms grew in the subcutaneous tissue of the mice. Microscopically and ultrastructurally, the neoplasms showed the typical morphology of undifferentiated high-grade pleomorphic sarcoma (UHGPS). Bone-related genes have been found to be expressed in both transformed cells and UHGPSs.

CONCLUSION

The present study suggests that UHGPSs are derived from BM stromal cells, probably mesenchymal stem cells.

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.

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.

Cell cycle of bone marrow CD34+ cells during autoimmune disease development in MRLMpJ/lpr mice

The development of autoimmune disease in Fas-deficient MRLMpJ/lpr mice is associated with a relative decrease in the content of bone marrow CD34+ cells, which can attest to intensification of migration of early hemopoietic precursors from the bone marrow. The intensity of CD34+ apoptosis is high in young healthy MRLMpJ/lpr mice in comparison with the control, but decreases during the development of autoimmune disease. Proliferative activity of CD34+ cell population surpassed the control in all mouse groups, except AID2. The detected shifts in quantitative and qualitative parameters of CD34+ cells attest to an important role of stem hemopoietic precursors in the formation of autoimmune disease in MRLMpJ/lpr mice.

Cotransplantation of marrow stromal cells may prevent lethal graft-versus-host disease in major histocompatibility complex mismatched murine hematopoietic stem cell transplantation

Marrow stromal cells (MSC) produce a microenvironment supporting hematopoiesis and may contribute immune tolerance because of low immunogenicity and the suppressive effect of alloreactivity. We investigated whether cotransplantation of MSC could prevent lethal graft-versus-host disease (GVHD) in major histocompatibility complex mismatched allogeneic murine hematopoietic stem cell transplantation (HSCT) using female BALB/c (H-2d, recipient) and C3H/He (H-2k, donor) mice. MSC were obtained from C3H/He bone marrow cells (BMC). MSC and irradiated BALB/c splenocytes (SP) were cocultured with C3H/He SP or BMC. Nonirradiated MSC did not inhibit the proliferation of alloantigen-stimulated BMC and SP. However, irradiated MSC suppressed the proliferation of alloantigen-stimulated SP at a level comparable with that of immunosuppressive agents, and the suppression by MSC was reversed to a significant degree by interleukin 2. Lethally irradiated BALB/c mice received transplants of donor cells according to the following experimental groups (group A, BMC only; group B, BMC and SP; group C, BMC, SP, and MSC; group D, BMC and MSC). The survival rate in group D was higher than in the other groups (P = .0057), and the clinical GVHD scores and serum levels of interferon-gamma were low in group D. Our results suggest that cotransplantation of MSC in HSCT prevents lethal GVHD, possibly by immune modulation.