R. Di Primio

Morphological and cytofluorimetric analysis of adult mesenchymal stem cells expanded ex vivo from periodontal ligament.

Many adult tissues contain a population of stem cells that have the ability of regeneration after trauma, disease or aging. Recently, there has been great interest in mesenchymal stem cells and their roles in maintaining physiological structure tissues and their studies have been considered very important and intriguing after having shown that this cell population can be expanded ex vivo to regenerate tissues not only of the mesenchymal lineage, such as intervertebral disc cartilage, bone, tooth-associated tissue, cardiomyocytes, but also to differentiate into cells derived from other embryonic layers, including neurons. Currently, different efforts have been focused on the identification of odontogenic progenitors from oral tissues. In this study we isolated and characterized a population of homogeneous human mesenchymal stem cells proliferating in culture with an attached well-spread morphology derived from periodontal ligament, tissue of ectomesenchymal origin, with the ability to form a specialized joint between alveolar bone and tooth. The adherent cells were harvested and expanded ex vivo under specific conditions and analysed by FACScan flow cytometer and morphological analysis was carried out by light, scanning and transmission electron microscopy. Our results displayed highly evident cells with a fibroblast like morphology and a secretory apparatus, probably indicating, that the enhanced function of the secretory apparatus of the mesenchymal stem cells may be associated with the secretion of molecules that are required to survive and proliferate. Moreover, the presence in periodontal ligament of CD90, CD29, CD44, CD166, CD 105, CD13 positive cells, antigens that are also identified as stromal precursors of the bone marrow, indicate that the periodontal ligament may turn out to be a new efficient source of the cells with intrinsic capacity to self-renewal, high ability to proliferate and differentiate, that can be utilized for a new approach to regenerative medicine and tissue engineering.

Effect of biologic therapies targeting tumour necrosis factor-α on cutaneous mesenchymal stem cells in psoriasis

Summary Background  Psoriasis is a Th1 immune‐mediated, inflammatory disease, in which skin lesions appear many years before the related metabolic and cardiovascular comorbidities, according to the theory of the ‘psoriatic march’. Inducible nitric oxide synthetase (iNOS), tumour necrosis factor (TNF)‐α and vascular endothelial growth factor (VEGF) are directly implicated in determining both skin lesions and systemic involvement in psoriasis. Reactive oxygen species actively promote the secretion of inflammatory Th1 cytokines directly involved in the pathogenesis of psoriasis.

The mesenchymal stem cell profile in psoriasis.

Background  The expression of inducible nitric oxide synthase (iNOS) and vascular endothelial growth factor (VEGF) and the level of total oxyradical scavenging capacity have been evaluated extensively in the cutaneous cells of patients with psoriasis. As yet, no indications are available about the undifferentiated cells, the mesenchymal stem cells (MSCs), isolated from skin.

Nitric oxide production during the osteogenic differentiation of human periodontal ligament mesenchymal stem cells

The critical tissues that require regeneration in the periodontium are of mesenchymal origin; therefore, the ability to identify, characterize and manipulate mesenchymal stem cells within the periodontium is of considerable clinical significance. In particular, recent findings suggest that periodontal ligament cells may possess many osteoblast-like properties. In the present study, periodontal ligament mesenchymal stem cells obtained from healthy volunteers were maintained in culture until confluence and then induced to osteogenic differentiation. Intracellular calcium ([Ca2+](i)) concentration and nitric oxide, important signalling molecules in the bone, were measured along with cell differentiation. Alkaline phosphatase activity was assayed and bone nodule-like structures were evaluated by means of morphological and histochemical analysis. Our results showed that the periodontal ligament mesenchymal stem cells underwent an in vitro osteogenic differentiation, resulting in the appearance of active osteoblast-like cells together with the formation of calcified deposits. Differentiating cells were also characterized by an increase of [Ca2+](i) and nitric oxide production. In conclusion, our data show a link between nitric oxide and the osteogenic differentiation of human periodontal ligament mesenchymal stem cells, thus suggesting that local reimplantation of expanded cells in conjugation with a nitric oxide donor could represent a promising method for treatment of periodontal defects.

Potential Role of Culture Mediums for Successful Isolation and Neuronal Differentiation of Amniotic Fluid Stem Cells

In recent years, the use of stem cells has generated increasing interest in regenerative medicine and cancer therapies. The most potent stem cells derive from the inner cell mass during embryonic development and their use yields serious ethical and methodological problems. Recently, a number of reports suggests that another suitable source of multipotent stem cells may be the amniotic fluid. Amniotic fluid mesenchymal stem cells (AFMSCs) are capable of extensive self-renewal, able to differentiate in specialized cells representative of all three germ layers, do not show ethical restriction, and display minimal risks of teratomas and a very low immunogenity. For all these reasons, amniotic fluid appears as a promising alternative source for stem cell therapy. Their recent discovery implies a lack of knowledge of their specific features as well as the existence of a protocol universally recognized as the most suitable for their isolation, growth and long-term conservation. In this study, we isolated stem cells from six amniotic fluids; these cells were cultured with three different culture mediums [Mesenchymal Stem Cell Medium (MSCGM), PC-1 and RPMI-1640], characterized by cytofluorimetric analysis, and then either frozen or induced to neuronal differentiation. Even if the immunophenotype seemed not to be influenced by culture medium (all six samples cultured in the above-mentioned mediums expressed surface antigens commonly found on stem cells), cells showed different abilities to differentiate into neuron-like cells and to re-start the culture after short-long-term storage. Cells isolated and cultured in MSCGM showed the highest proliferation rate, and formed neuron-like cells when sub-plated with neuronal differentiation medium. Cells from PC-1, on the contrary, displayed an increased ability to re-start culture after short-long term storage. Finally, cells from RPMI-1640, even if expressing stem cells markers, were not able to differentiate in neuron-like cells. Further studies are still needed in order to assess the effective role of culture medium for a successful isolation, growth, differentiation and storage of AFMSCs, but our data underline the importance of finding a universally accepted protocol for the use of these cells.

CD38 is constitutively expressed in the nucleus of human hematopoietic cells

CD38 is a type II glycoprotein that acts both as a bifunctional enzyme, responsible for the synthesis and hydrolysis of cyclic ADP‐ribose, and as a signal‐transducing surface receptor. Although CD38 was originally described as a plasma membrane molecule, several reports indicate that CD38 is expressed in the nucleus, even in cells known to be CD38 surface‐negative. In this study, firstly we investigated the presence of nuclear CD38 by immunofluorescence and confocal microscopy using a panel of hematopoietic cell lines that exhibit different levels of CD38 plasma membrane expression. Our second aim was to explore the relationship between the nuclear and plasma membrane forms of CD38 in human cell lines which represent discrete early maturation stages of the human lymphoid and myeloid compartments. Our results indicate that CD38 is constitutively present in the nucleus of cells belonging to distinct lineages. Furthermore, nuclear CD38 appears to be independent of the plasma membrane pool. The presence of nuclear CD38 during different stages of hematopoietic differentiation suggests that it may play a role in the control of nuclear Ca2+ homeostasis and NAD levels. J. Cell. Biochem. 105: 905–912, 2008.

DMSO modifies structural and functional properties of RPMI-8402 cells by promoting programmed cell death.

Apoptosis in lymphoid cells can be induced in different ways depending on cell type and acquired signal. Biochemical modifications occur at an early phase of cell death while at late times the typical morphological features of apoptosis can be visualized. The aim of this study is to verify by multiparametric analyses the plasma membrane fluidity, the intracellular Ca2+ concentration and the nitric oxide synthase (NOS) activity during cell death progression induced by DMSO treatment. The RPMI-8402 human pre-T lymphoblastoid cell line was induced to cell death by DMSO. Analyses rescued at early times of treatment prove a substantial modification of plasma membrane fluidity associated with an increase of intracellular Ca2+. Moreover, these modifications are associated with an up regulation of NOS activity. Our results are consistent with the hypothesis that programmed cell death can be induced by up regulation of the intracellular Ca2+ associated with an increase of cell membrane fluidity. The apoptotic mechanisms seem to involve not only membrane damage and increased intracellular calcium levels but also production of nitric oxide.

Characterization and profiling of immunomodulatory genes in resident mesenchymal stem cells reflect the Th1-Th17/Th2 imbalance of psoriasis.

The expression of genes encoding for Th1, Th2 and Th17 cytokines has been extensively evaluated in differentiated skin cells of psoriatic patients. The microenvironment exerts a control on the phenotype of resident mesenchymal stem cells (MSCs) into the skin of psoriasis patients. Aim of the study was to extensively evaluate the relative expression of 43 genes encoding for Th1, Th2 and Th17 cytokines in MSCs isolated from skin of psoriasis patients. MSCs resident into psoriatic skin were isolated, characterized and profiled by PCR array for the relative expression of genes encoding for cytokines involved in Th1, Th2 and Th17 pathways. MSCs isolated from the skin of healthy subjects were used as control. The MSCs isolated from skin of psoriasis patients showed a greater relative expression of the most part of the analyzed genes encoding for Th1 and Th17 cytokines: INF-γ, CCR5, CXCL9, CXCL10, IL6, IL8, TNF-α, IL23A, CCL2, CCL20, CXCL2, CXCL5, IL17C, IL17F, IL17RA, IL21, TLR2 than healthy subjects. On the contrary, the relative expression of genes encoding for Th2 cytokines: CCL1, CCL22, CXCL12, IL2, IL3, IL4, IL13B, IL 22, IL 27, TGF-β1, was similar between the MSCs isolated from psoriasis and healthy subjects. In conclusion, the MSCs isolated from psoriasis show an imbalance between the Th1-Th17 and Th2 pathways, which reflects the well-known abnormal balance observed in differentiated skin cells. This evidence could strengthen the hypothesis of an early involvement of resident MSCs in the pathogenesis of psoriasis.

Skin-derived mesenchymal stem cells: isolation, culture, and characterization.

The increasing interest about stem cell research is linked to the promise of developing such treatments for many life-threatening, debilitating diseases and for cell replacement therapies. Among the various human tissues, skin represents a source characterized by great accessibility and availability with noninvasive procedures and without risks of oncogenesis after their transplantation. In this aim, the identification of suitable protocols for the isolation, characterization, and long-term storage has a pivotal role.

Th1‐Th17 and Th2 imbalance in Mesenchymal Stem Cells of adult patients with atopic dermatitis: at the origin of the problem

Atopic dermatitis (AD) is a chronic and inflammatory disease characterized by a marked imbalance of T helper (Th)2 vs. Th1/Th17 cells in the early phase of AD, whereas a mixed Th1/Th2 pattern of inflammation is usually found at the chronic stage. These features have not been extensively evaluated in undifferentiated skin cells of patients affected by AD.