J. Kiss

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 β‐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 106 BMCs per 105 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 β‐cells were found in the recovered animals, indicating a graft‐initiated endogenous repair process. Moreover, MSC injection caused the disappearance of β‐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 β‐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.

Nonoperative management of esophageal perforations: Is it justified?

OBJECTIVE Experiences obtained with nonoperative treatment (NOT), i.e. total prohibition of per oral food intake for a minimum of 7 days, administration of combinations of broad-spectrum antibiotics, and parenteral hyperalimentation, are described in the management of esophageal perforations. SUMMARY BACKGROUND DATA The place, value, and indication of NOT in the management of esophageal perforation has not yet been unequivocally defined. As a result, contradictory data have been published regarding the outcome of NOT. METHODS During the past 15 years (1979 to 1994), 20 of 86 patients (23.3%) with esophageal perforation have been treated nonoperatively from the outset. In this group, perforations were located to the upper, middle, and lower third of the esophagus in 50%, 30%, and 20%, respectively. In the operative management group (OT)--in which conservative (drainage, endeprothesis), reconstructive (suture, reinforced suture), and radical (resection) surgical methods were applied--lesions were preponderantly located in the lower one third of the esophagus (56.1%--37/66). As to the interval between the perforation and the onset of treatment, 14 patients had been diagnosed within 24 hours, whereas in 6 cases treatment had been begun beyond 24 hours. RESULTS NOT could be successfully carried out in 16 patients; the decision to use NOT had to be revised in 4 other cases (Table 1). Two patients were lost; the mortality rate was 10% (2 of 20). The rate of complications was lower in the NOT group (20%, or 4 of 20) than in the OT group (50%, or 33 of 66). CONCLUSIONS NOT can be suggested for the treatment of intramural perforations. In the case of transmural perforation, this approach should be taken into consideration if the esophageal lesion is circumscribed, is not in neoplastic tissue, is not in the abdominal cavity, and is not accompanied by simultaneous obstructive esophageal disease; in addition, symptoms and signs of septicemia should be absent.

Inappropriate notch activity and limited mesenchymal stem cell plasticity in the bone marrow of patients with myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are a heterogeneous group of hematological disorders characterized by ineffective hematopoiesis, enhanced bone marrow apoptosis and frequent progression to acute myeloid leukemia. Several recent studies suggested that, besides the abnormal development of stem cells, microenvironmental alterations are also present in the MDS bone marrow. In this study, we have examined the relative frequencies of stem and progenitor cell subsets of MDS and normal hematopoietic cells growing on stromal cell layers established from MDS patients and from normal donors. When hematopoietic cells from MDS patients were co-cultured with normal stromal cells, the frequency of either early or late cobblestone area-forming cells (CAFC) was significantly lower compared to the corresponding normal control values in 4 out of 8 patients. In the opposite situation, when normal hematopoietic cells were incubated on MDS stromal cells, the CAFC frequencies were decreased in 5 out of 6 patients, compared to normal stromal layer-containing control cultures. Moreover, a soluble Notch ligand (Jagged-1 protein) was an inhibitor of day-35-42 CAFC when normal hematopoietic cells were cultured with normal or MDS stromal cells, but was unable to inhibit MDS stem and early progenitor cell growth (day-35-42 CAFC) on pre-established stromal layers. These findings suggest that in early hematopoietic cells isolated from MDS patients the Notch signal transduction pathway is disrupted. Furthermore, there was a marked reduction in the plasticity of mesenchymal stem cells of MDS patients compared with those of normal marrow donors, in neurogenic and adipogenic differentiation ability and hematopoiesis supporting capacityin vitro. These results are consistent with the hypothesis that when alterations are present in the myelodysplastic stroma environment along with intrinsic changes in a hematopoietic stem/progenitor cell clone, both factors might equally contribute to the abnormal hematopoiesis in MDS.

Identical, similar or different? Learning about immunomodulatory function of mesenchymal stem cells isolated from various mouse tissues: bone marrow, spleen, thymus and aorta wall

Mesenchymal stem or multipotent stromal cells (MSCs) have been implicated in tissue maintenance and repair and regulating immune effector cells through different mechanisms. These functions in mouse were primarily described for bone marrow (BM)-derived MSCs. To learn more about MSCs of different tissue origin, we compared the immunophenotype, differentiation ability to adipocyte and bone and immunomodulatory activity of MSCs isolated from BM, spleen, thymus and aorta wall of 14-day-old C57Bl/6 mice. The established cell lines fulfilled the requirements described for MSCs in terms of morphology, surface marker expression and differentiation potential although they were distinguishable regarding the expression pattern of the MSC markers and ability generating other cell types. Most importantly, a remarkable diversity was shown in the capacity of inhibition of mitogen- and alloantigen-induced T-cell proliferation, since BM- and spleen-derived MSCs were the most powerful aorta-derived MSCs were less effective, whereas thymus-derived mesenchymal cells were unable to block T-cell growth in vitro. Accordingly, BM, spleen and aorta, but not thymus-derived MSCs, in combination with BM hematopoietic cells were equally efficient to prevent streptozotocin-induced diabetes in vivo. These findings suggested that MSCs residing in different organs might stem from common ancestor; however, once populating into a given tissue microenvironment, they acquire specific properties mainly in the term of the immunoregulatory function.

Association of microvessel density with infiltrating cells in human cutaneous malignant melanoma

Vascularization and host response to malignant tumors may have common molecular regulators, therefore, we analyzed the relationship between microvessel density (MVD) and tumor infiltrating cells in cutaneous malignant melanoma. Density of lymphocyte subpopulations, macrophages, dendritic cells and CD34+ microvessels was determined by immunohistochemistry in primary tumor samples from fifty-two patients with melanoma thicker than 1 mm. Intratumoral MVD did not show significant association with infiltration for any of these cell types. In the case of peritumoral reactive cell densities analyzed in the whole patient population, a positive correlation of MVD was found with CD3+ T cell density. This association was stronger in melanomas >4.0 mm and in visceral metastatic tumors. In these subgroups similar phenomenon was observed for CD8+ cells. We found significant correlation of MVD with CD68+ macrophage density only in the highest thickness category, and weak associations with B-cell and dendritic cell infiltration in visceral metastatic cases. MVD did not vary significantly in tumors categorized according to thickness, localization, ulceration or histological type. However, both intratumoral MVD and macrophage infiltration were significantly higher in male patients compared to females. The correlation of immune cell density with tumor vascularization and gender differences in vascularity and macrophage infiltration of melanoma deserve further attention.

In vitro expansion of long-term repopulating hematopoietic stem cells in the presence of immobilized Jagged-1 and early acting cytokines.

There is an increasing body of evidence that suggests that genes involved in cell fate decisions and pattern formation during development also play a key role in the continuous cell fate decisions made by adult tissue stem cells. Here we show that prolonged in vitro culture (14 days) of murine bone marrow lineage negative cells in medium supplemented with three early acting cytokines (stem cell factor, Flk‐2/Flt‐3 ligand, thrombopoietin) and with immobilized Notch ligand, Jagged‐1, resulted in robust expansion of serially transplantable hematopoietic stem cells with long‐term repopulating ability. We found that the absolute number of marrow cells was increased ∼8 to 14‐fold in all cultures containing recombinant growth factors. However, the frequency of high quality stem cells was markedly reduced at the same time, except in cultures containing growth factors and Jagged‐1‐coated Sepharose‐4B beads. The absolute number of hematopoietic cells with long‐term repopulating ability was increased ∼10 to 20‐fold in the presence of multivalent Notch ligand. These results support a role for combinatorial effects by Notch and cytokine‐induced signaling pathways in regulating hematopoietic stem cell fate and to a potential role for Notch ligand in increasing cell numbers in clinical stem cell transplantation.

[Mesenchymal stem cells and the immune system--immunosuppression without drugs?].

Mesenchymal stem cells (MSC) - isolated from various tissues in humans and other species - are one of the most promising adult stem cell types due to their availability and the relatively simple requirements for in vitro expansion. They have the capacity to differentiate into several tissues, including bone, cartilage, tendon, muscle and adipose, and produce growth factors and cytokines that promote hematopoietic cell expansion and differentiation. In vivo, MSCs are able to repair damaged tissue from kidney, heart, liver, pancreas and gastrointestinal tract. Furthermore, they also have anti-proliferative, immunomodulatory and anti-inflammatory effects, but evoke only little immune reactivity. Although the mechanism underlying the immunosuppressive effects of MSCs has not been clearly defined, their immunosuppressive properties have already been exploited in the clinical setting. Therefore, in the future, MSCs might have implications for treatment of allograft rejection, graft-versus-host disease, rheumatoid arthritis, autoimmune inflammatory bowel disease and other disorders in which immunomodulation and tissue repair are required. The aim of this review is to critically analyze the field of MSC biology, particularly with respect to their immunomodulatory properties and potential clinical use in the future.

[Beyond genetics--the emerging role of epigenetics and its clinical aspects].

Analysis of genomic sequences has clearly shown that the genomic differences among species do not explain the diversity of life. The genetic code itself serves as only a part of the dynamic complexity that results in the temporal and spatial changes in cell phenotypes during development. It has been concluded that the phenotype of a cell and of the organism as a whole is more influenced by environmentally-induced changes in gene activity than had been previously thought. The emerging field of epigenetics focuses on molecular marks on chromatin; called the epigenome, which serve as transmitters between the genome and the environment. These changes not only persist through multiple cell division cycles, but may also endure for multiple generations. Irregular alterations of the epigenome; called epimutations, may have a decisive role in the etiology of human pathologies such as malignancies and other complex human diseases. Epigenetics can provide the missing link between genetics, disease and the environment. Therefore, this field may have an increasing impact on future drug design and serve as a basis for new therapeutic/preventative approaches.

A mesenchymalis őssejtek és az immunrendszer – immunszuppresszió gyógyszerek nélkül?@@@Mesenchymal stem cells and the immune system – Immunosuppression without drugs

Mesenchymal stem cells (MSC) - isolated from various tissues in humans and other species - are one of the most promising adult stem cell types due to their availability and the relatively simple requirements for in vitro expansion. They have the capacity to differentiate into several tissues, including bone, cartilage, tendon, muscle and adipose, and produce growth factors and cytokines that promote hematopoietic cell expansion and differentiation. In vivo, MSCs are able to repair damaged tissue from kidney, heart, liver, pancreas and gastrointestinal tract. Furthermore, they also have anti-proliferative, immunomodulatory and anti-inflammatory effects, but evoke only little immune reactivity. Although the mechanism underlying the immunosuppressive effects of MSCs has not been clearly defined, their immunosuppressive properties have already been exploited in the clinical setting. Therefore, in the future, MSCs might have implications for treatment of allograft rejection, graft-versus-host disease, rheumatoid arthritis, autoimmune inflammatory bowel disease and other disorders in which immunomodulation and tissue repair are required. The aim of this review is to critically analyze the field of MSC biology, particularly with respect to their immunomodulatory properties and potential clinical use in the future.

A mesenchymalis ôssejtek és az immunrendszer - immunszuppresszió gyógyszerek nélkül?

Mesenchymal stem cells (MSC) - isolated from various tissues in humans and other species - are one of the most promising adult stem cell types due to their availability and the relatively simple requirements for in vitro expansion. They have the capacity to differentiate into several tissues, including bone, cartilage, tendon, muscle and adipose, and produce growth factors and cytokines that promote hematopoietic cell expansion and differentiation. In vivo, MSCs are able to repair damaged tissue from kidney, heart, liver, pancreas and gastrointestinal tract. Furthermore, they also have anti-proliferative, immunomodulatory and anti-inflammatory effects, but evoke only little immune reactivity. Although the mechanism underlying the immunosuppressive effects of MSCs has not been clearly defined, their immunosuppressive properties have already been exploited in the clinical setting. Therefore, in the future, MSCs might have implications for treatment of allograft rejection, graft-versus-host disease, rheumatoid arthritis, autoimmune inflammatory bowel disease and other disorders in which immunomodulation and tissue repair are required. The aim of this review is to critically analyze the field of MSC biology, particularly with respect to their immunomodulatory properties and potential clinical use in the future.