Bone marrow-derived hematopoietic stem and progenitor cells infiltrate allogeneic and syngeneic transplants

Two lineages of immune cells that differentially express the vitamin D receptor

Since 1983 it has been known that monocytes and activated T and B cells expressed the vitamin D receptor (VDR) and are therefore vitamin D targets. New data identified two lineages of immune cells that can be differentiated by the expression of the VDR. Monocytes, macrophages, neutrophils, and hematopoietic stem cells were mostly from VDR positive lineages. T cells, ILC1 and ILC3 were also largely VDR positive, which is consistent with the known effects of vitamin D as regulators of type-1 and type-3 immunity. Activation of the VDR negative T cells did not induce the expression of the VDR reporter, suggesting that perhaps only a subset of the T cells in the periphery express the VDR. When activated, the VDR negative T cells responded as if they were VDR knockout T cells in that they made more IFN-γ and proliferated faster than the VDR positive T cells. The ability of vitamin D to regulate immune function will depend on which cells express the VDR and a better understanding of the signals that regulate VDR expression in immune cells.

Immunostimulatory effects of a subcritical water extract of Ganoderma

Ganoderma, a medicinal mushroom with various physiological activities, has been extensively investigated regarding its effectiveness. The aim of the present study was to examine the effects of a subcritical water extract of Ganoderma (SWEG) on the immune system. The use of subcritical water with a higher temperature and pressure than hot water allows efficient elution of components from natural products. As an evaluation of the effectiveness of SWEG, a cell proliferation and a cell differentiation test were carried out using A-6 cells, a model of hematopoietic stem cells. Furthermore, an oral administration test in mice was conducted to examine the effects of SWEG on the number and function of immune cells. As a result, SWEG was revealed to promote both self-renewal and differentiation into immune cells such as T cells and natural killer (NK) cells in experiments with A-6 cells. These results were not obtained in experiments using hot water extract of Ganoderma lucidum and Ganoderma sinense. The oral administration test in mice demonstrated that SWEG increased hematopoietic precursor cells, immature B cells, and NK cells in the bone marrow, and T cells in the thymus. In addition, SWEG enhanced the immune functions in the spleen by promoting granzyme B expression and NK cell activity. SWEG was demonstrated to be a food material that acts on HSCs and regulates immunity in vivo.

Hematopoietic Stem/Progenitor Cell Dependent Participation of Innate Lymphoid Cells in Low-Intensity Sterile Inflammation

Hematopoietic stem/progenitor cells (HSPC) are characterized by their unique capacities of self-renewal and multi-differentiation potential. This second property makes them able to adapt their differentiation profile depending on the local environment they reach. Taking advantage of an animal model of peritonitis, induced by injection of the TLR-2 ligand, zymosan, we sought to study the relationship between bone marrow-derived hematopoietic stem/progenitor cells (BM-HSPCs) and innate lymphoid cells (ILCs) regarding their emergence and differentiation at the site of inflammation. Our results demonstrate that the strength of the inflammatory signals affects the capacity of BM-derived HSPCs to migrate and give rise in situ to ILCs. Both low- and high-dose of zymosan injections trigger the appearance of mature ILCs in the peritoneal cavity where the inflammation occurs. Herein, we show that only in low-dose injected mice, the recovered ILCs are dependent on an in situ differentiation of BM-derived HSPCs and/or ILC2 precursors (ILC2P) wherein high-dose, the stronger inflammatory environment seems to be able to induce the emergence of ILCs independently of BM-derived HSPCs. We suggest that a relationship between HSPCs and ILCs seems to be affected by the strength of the inflammatory stimuli opening new perspectives in the manipulation of these early hematopoietic cells.

Chimeric Allografts Induced by Short-Term Treatment With Stem Cell-Mobilizing Agents Result in Long-Term Kidney Transplant Survival Without Immunosuppression: A Study in Rats

Transplant tolerance allowing the elimination of lifelong immunosuppression has been the goal of research for 60 years. The induction of mixed chimerism has shown promise and has been extended successfully to large animals and to the clinic; however, it remains cumbersome and requires heavy early immunosuppression. In this study, we reported that four injections of AMD3100, a CXCR4 antagonist, plus eight injections of low-dose FK506 (0.05 mg/kg per day) in the first week after kidney transplantation extended survival, but death from renal failure occurred at 30-90 days. Repeating the same course of AMD3100 and FK506 at 1, 2 and 3 mo after transplant resulted in 92% allograft acceptance (n = 12) at 7 mo, normal kidney function and histology with no further treatment. Transplant acceptance was associated with the influx of host stem cells, resulting in a hybrid kidney and a modulated host immune response. Confirmation of these results could initiate a paradigm shift in posttransplant therapy.

Chimeric Allografts Induced by Short-Term Treatment With Stem Cell Mobilizing Agents Result in Long-Term Kidney Transplant Survival Without Immunosuppression: II, Study in Miniature Swine

Transplantation is now lifesaving therapy for patients with end-stage organ failure but requires lifelong immunosuppression with resultant morbidity. Current immunosuppressive strategies inhibit T cell activation and prevent donor-recipient engagement. Therefore, it is not surprising that few host cells are demonstrated in donor grafts. However, our recent small animal studies found large numbers of recipient stem cells present after transplantation and pharmacological mobilization, resulting in a chimeric, repopulated organ. We now confirm these findings in a well-characterized large animal preclinical model. Here, we show that AMD3100 and FK506 mobilization of endogenous stem cells immediately post kidney transplantation combined with repeat therapy at 1, 2, and 3 months led to drug-free long-term survival in maximally immunologically mismatched swine. Three long-term recipients have stable chimeric transplants, preserved antidonor skin graft responses, and normal serum creatinine levels despite withdrawal of all medication for 3 years.

Bone marrow-derived progenitor cells in de novo liver regeneration in liver transplant

The study was designed (1) to examine the hypothesis that circulating progenitor cells play a role in the process of de novo regeneration in human liver transplants and that these cells arise from a cell population originating in, or associated with, the bone marrow and (2) to investigate whether the transplanted liver volume has an effect on the circulating recipient-derived progenitor cells that generate hepatocytes during this process. Clinical data and liver tissue characteristics were analyzed in male individuals who underwent sex-mismatched adult-to-adult living donor liver transplantation using dual left lobe grafts. Dual left lobe grafts were examined at the time of transplantation and 19 to 27 days after transplantation. All recipients showed recovery of normal liver function and a significant increase in the volume of the engrafted left lobes after transplantation. Double staining for a Y-chromosome probe and the CD31 antigen showed the presence of hybrid vessels composed of recipient-derived cells and donor cells within the transplanted liver tissues. Furthermore, CD34-expressing cells were observed commingling with Y-chromosome+ cells. The ratio of recipient-derived vessels and the number of Y+ CD34+ cells tended to be higher when smaller graft volumes underwent transplantation. These findings suggest that the recruitment of circulating bone marrow-derived progenitor cells could contribute to vessel formation and de novo regeneration in human liver transplants. Moreover, graft volume may be an important determinant for the active mobilization of circulating recipient-derived progenitor cells and their contribution to liver regeneration.