Localized Cell-Surface Sampling of a Secreted Factor Using Cell-Targeting Beads.

Intercellular communication through the secretion of soluble factors plays a vital role in a wide range of biological processes (e.g., homeostasis, immune response), yet identification and quantification of many of these factors can be challenging due to their degradation or sequestration in cell culture media prior to analysis. Here, we present a customizable bead-based system capable of simultaneously binding to live cells (through antibody-mediated cell tethering) and capturing cell-secreted molecules. Our functionalized beads capture secreted molecules (e.g., hepatocyte growth factor secreted by fibroblasts) that are diminished when sampled via traditional supernatant analysis techniques (p < 0.05), effectively rescuing a reduced signal in the presence of neutralizing components in the cell culture media. Our system enables capture and analysis of molecules integral to chemical communication that would otherwise be markedly decreased prior to analysis.

Multiple roles of CD90 in cancer.

THY1 (CD90) is a 25-37-kDa heavily N-glycosylated, glycophosphatidylinositol (GPI) anchored cell surface protein. It is usually expressed on thymocytes, mesenchymal stem cells, hematopoietic stem cells, natural killer cells, neurons, endothelial cells, renal glomerular mesangial cells, follicular dendritic cells, fibroblasts, and myofibroblasts. It has been found to regulate cell adhesion, migration, apoptosis, axon growth, cell-cell and cell-matrix interactions, T-cell activation, and fibrosis. Several reports have shown that CD90 has an important role in cancer in regulating cancer cell proliferation, metastasis, and angiogenesis. There are also evidences that CD90 is an important prognostic marker in many cancers. Consequently, therapies that target CD90 have great promise in treating many cancers. However, several studies also indicate a contradictory role for CD90, where it acts as a tumor suppressor. In this review, we summarize the expression, function of CD90 in different cancers and its possible use as a biomarker or a therapeutic target in cancer. The challenges and future prospects for the use of CD90 for clinical applications are also discussed in this review.

MSC surface markers (CD44, CD73, and CD90) can identify human MSC-derived extracellular vesicles by conventional flow cytometry.

BACKGROUND: Human mesenchymal stromal cells (hMSC) are multipotent cells with both regenerative and immunomodulatory activities making them an attractive tool for cellular therapy. In the last few years it has been shown that the beneficial effects of hMSC may be due to paracrine effects and, at least in part, mediated by extracellular vesicles (EV). EV have emerged as important mediators of cell-to-cell communication. Flow cytometry (FCM) is a routine technology used in most clinical laboratories and could be used as a methodology for hMSC-EV characterization. Although several reports have characterized EV by FCM, a specific panel and protocol for hMSC-derived EV is lacking. The main objective of our study was the characterization of hMSC-EV using a standard flow cytometer. METHODS: Human MSC from bone marrow of healthy donors, mesenchymal cell lines (HS-5 and hTERT) and a leukemic cell line (K562 cells) were used to obtain EV for FCM characterization. EV released from the different cell lines were isolated by ultracentrifugation and were characterized, using a multi-parametric analysis, in a conventional flow cytometer. EV characterization by transmission electron microscopy (TEM), western blot (WB) and Nano-particle tracking analysis (NTA) was also performed. RESULTS: EV membranes are constituted by the combination of specific cell surface molecules depending on their cell of origin, together with specific proteins like tetraspanins (e.g. CD63). We have characterized by FCM the EV released from BM-hMSC, that were defined as particles less than 0.9 µm, positive for the hMSC markers (CD90, CD44 and CD73) and negative for CD34 and CD45 (hematopoietic markers). In addition, hMSC-derived EV were also positive for CD63 and CD81, the two characteristic markers of EV. To validate our characterization strategy, EV from mesenchymal cell lines (hTERT/HS-5) were also studied, using the leukemia cell line (K562) as a negative control. EV released from mesenchymal cell lines displayed the same immunophenotypic profile as the EV from primary BM-hMSC, while the EV derived from K562 cells did not show hMSC markers. We further validated the panel using EV from hMSC transduced with GFP. Finally, EV derived from the different sources (hMSC, hTERT/HS-5 and K562) were also characterized by WB, TEM and NTA, demonstrating the expression by WB of the exosomal markers CD63 and CD81, as well as CD73 in those from MSC origin. EV morphology and size/concentration was confirmed by TEM and NTA, respectively. CONCLUSION: We described a strategy that allows the identification and characterization by flow cytometry of hMSC-derived EV that can be routinely used in most laboratories with a standard flow cytometry facility.

Blood vessels expressing CD90 in human and rat brain tumors.

Blood vessels in brain tumors, particularly glioblastomas, have been shown to express CD90. CD90(+) cells in and around blood vessels in cancers including brain tumors have been identified as endothelial cells, cancer stem cells, fibroblasts or pericytes. In this study, we aimed to determine the nature or type(s) of cells that express CD90 in human brain tumors as well as an experimental rat glioma model by double immunofluorescence staining. The majority of CD90(+) cells in human glioblastoma tissue expressed CD31, CD34 and von Willebrand factor, suggesting that they were endothelial cells. Vasculatures in a metastatic brain tumor and meningioma also expressed CD90. CD90(+) cells often formed glomeruloid structures, typical of angiogenesis in malignant tumors, not only in glioblastoma but also in metastatic tumors. Some cells in the middle and outer layers of the vasculatures expressed CD90. Similar results were obtained in the rat glioma model. There were cells expressing both α-smooth muscle actin and CD90 in the middle layer of blood vessels, indicating that smooth muscle cells and/or pericytes may express CD90. CD90(+) vasculatures were surrounded by tumor-associated macrophages (TAMs). Thus, in addition to endothelial cells, some other types of cells, such as smooth muscle cells, pericytes and fibroblasts constituting the vasculature walls in brain tumors expressed CD90. Because CD90 has been shown to interact with integrins expressed by circulating monocytes, CD90 might be involved in angiogenesis through recruitment and functional regulation of TAMs in tumors. CD90(+) vasculatures may also interact with tumor cells through interactions with integrins. Because CD90 was not expressed by vasculatures in normal brain tissue, it might be a possible therapeutic target to suppress angiogenesis and tumor growth.

Tissue non-specific alkaline phosphatase production by human dental pulp stromal cells is enhanced by high density cell culture.

The cell surface hydrolase tissue non-specific alkaline phosphatase (TNAP) (also known as MSCA-1) is used to identify a sub-population of bone marrow stromal cells (BMSCs) with high mineralising potential and is found on subsets of cells within the dental pulp. We aim to determine whether TNAP is co-expressed by human dental pulp stromal cells (hDPSCs) alongside a range of BMSC markers, whether this is an active form of the enzyme and the effects of culture duration and cell density on its expression. Cells from primary dental pulp and culture expanded hDPSCs expressed TNAP. Subsequent analyses revealed persistent TNAP expression and co-expression with BMSC markers such as CD73 and CD90. Flow cytometry and biochemical assays showed that increased culture durations and cell densities enhanced TNAP expression by hDPSCs. Arresting the hDPSC cell cycle also increased TNAP expression. These data confirm that TNAP is co-expressed by hDPSCs together with other BMSC markers and show that cell density affects TNAP expression levels. We conclude that TNAP is a potentially useful marker for hDPSC selection especially for uses in mineralised tissue regenerative therapies.

Isolation and characterization of human mesenchymal stem cells from gingival connective tissue.

BACKGROUND AND OBJECTIVE: The main purpose of this study was to isolate and characterize gingival connective tissue-derived mesenchymal stem cells (GMSCs). The secondary purpose was to present a modified isolation method for the GMSCs. MATERIAL AND METHODS: Collected healthy gingival tissue samples were de-epithelialized and minced into small fragments. The tissues were digested by dispase and collagenase IV for 30 min. The first digested cell suspension was discarded, and then additional digestion was performed to the remaining cells in the same solution for 90 min. The isolated cells from gingiva was incubated in 37°C humidified condition and observed by inverted microscope. Cytoskeletal morphology was evaluated by phalloidin immunofluorescence. Potency of the cells was tested by colony-forming unit fibroblast assay. GMSCs were characterized by osteogenic, adipogenic and chondrogenic differentiation, and flow cytometric, immunofluorescence analysis. RESULTS: GMSCs showed spindle-shaped, fibroblast-like morphology, colony-forming abilities, adherence to plastic and multilineage differentiation (osteogenic, adipogenic, chondrogenic) potency. GMSCs expressed CD44, CD73, CD90 and CD105, but did not express CD14, CD45, CD34 and CD19 in flow cytometry. Expression of stem cell markers (SSEA-4, STRO-1, CD146, CD166 and CD271) and a mesenchymal marker (vimentin) were observed by immunofluorescence. CONCLUSIONS: In conclusion, we isolated and characterized stem cells from human gingival connective tissue with modified protocol. GMSCs showed multipotency with high proliferation and characteristics of mesenchymal stem cells. GMSCs are promising sources for tissue engineering and may be obtained during routine procedures under local anesthesia. Further research is needed to evaluate the potential of GSMCs' proliferation and cryopreservation.

Interferon-γ regulates the function of mesenchymal stem cells from oral lichen planus via indoleamine 2,3-dioxygenase activity.

BACKGROUND: Little is known about mesenchymal stem cells (MSCs) in normal or inflammatory oral mucosal tissues, such as in oral lichen planus (OLP). Our objectives were to identify, isolate, and characterize MSCs from normal human oral mucosa and OLP lesions, and to evaluate indoleamine 2,3 dioxygenase (IDO) activity in mediating immunomodulation of MSCs from these tissues. METHODS: Expressions of MSCs-related markers were examined in isolated cells by flow cytometry. Self-renewal and multilineage differentiations were studied to characterize these MSCs. Interferon-γ (IFN-γ), IDO, and STRO-1 were assessed by immunofluorescence. MSCs from oral mucosa and OLP or IFN-γ-pretreated MSCs were co-cultured with allogeneic mixed lymphocyte reaction assays (MLR). Proliferation and apoptosis of MLR or MSCs were detected by CCK8 and the annexin V-FITC apoptosis detection kit, respectively. IDO expression and activity were measured by real-time PCR, Western blotting, and high-performance liquid chromatography. RESULTS: Isolated cells from oral mucosa and OLP expressed MSC-related markers STRO-1, CD105, and CD90 but were absent for hematopoietic stem cell markers CD34. Besides, they all showed self-renewal and multilineage differentiation capacities. MSCs in OLP presented STRO-1/IDO+ phenotype by immunofluorescence. MSCs and IFN-γ-pretreated MSCs could inhibit lymphocyte proliferation via IDO activity, but not via cell apoptosis. Long-term IFN-γ could also inhibit MSC proliferation via IDO activity. CONCLUSIONS: Mesenchymal stem cells can be isolated from human oral mucosa and OLP tissues. Besides self-renewal and multilineage differentiation properties, these cells may participate in immunomodulation mediated by IFN-γ via IDO activity in human OLP.

Detection of pancreatic ductal adenocarcinoma in mice by ultrasound imaging of thymocyte differentiation antigen 1.

BACKGROUND & AIMS: Early detection of pancreatic ductal adenocarcinoma (PDAC) allows for surgical resection and increases patient survival times. Imaging agents that bind and amplify the signal of neovascular proteins in neoplasms can be detected by ultrasound, enabling accurate detection of small lesions. We searched for new markers of neovasculature in PDAC and assessed their potential for tumor detection by ultrasound molecular imaging. METHODS: Thymocyte differentiation antigen 1 (Thy1) was identified as a specific biomarker of PDAC neovasculature by proteomic analysis. Up-regulation in PDAC was validated by immunohistochemical analysis of pancreatic tissue samples from 28 healthy individuals, 15 with primary chronic pancreatitis tissues, and 196 with PDAC. Binding of Thy1-targeted contrast microbubbles was assessed in cultured cells, in mice with orthotopic PDAC xenograft tumors expressing human Thy1 on the neovasculature, and on the neovasculature of a genetic mouse model of PDAC. RESULTS: Based on immunohistochemical analyses, levels of Thy1 were significantly higher in the vascular of human PDAC than chronic pancreatitis (P = .007) or normal tissue samples (P < .0001). In mice, ultrasound imaging accurately detected human Thy1-positive PDAC xenografts, as well as PDACs that express endogenous Thy1 in genetic mouse models of PDAC. CONCLUSIONS: We have identified and validated Thy1 as a marker of PDAC that can be detected by ultrasound molecular imaging in mice. The development of a specific imaging agent and identification of Thy1 as a new biomarker could aid in the diagnosis of this cancer and management of patients.

Surface markers of hepatocellular cancer stem cells and their clinical potential.

Cancer stem cells (CSCs) are a small subpopulation of cells within tumors with capabilities of self-renewal, differentiation, and tumorigenicity when transplanted into immune-comprised mice. Accumulating evidences have shown that CSCs or tumor-initiating cells are key drivers of tumor formation and progression in both solid tumors and haematological malignancies. Identification of the CSCs or tumor-initiating cells is a fundamental and important problem in cancer research. There is still a lack of consensus regarding the existence of a "global" marker for CSCs in different human cancers, but isolated CSCs have shown both the tumor-propagating ability in immune-compromised mice and the capacity to fully recapitulate the original heterogeneity of cell types. Several cell surface markers, including CD133, CD44 and CD90, were often used to identify and enrich CSCs. Although not all types of cancer follow the CSC theory, it provides an attractive cellular mechanism to account for the therapeutic resistance and recurrence of the disease. Here we provide a brief review regarding the markers for identification of CSCs in hepatocellular cancer, allowing us to deep understand of the cellular organization of HCC and to develop therapies that target specific CSCs.

Reconstruction of human elastic cartilage by a CD44+ CD90+ stem cell in the ear perichondrium.

Despite the great demands for treating craniofacial injuries or abnormalities, effective treatments are currently lacking. One promising approach involves human elastic cartilage reconstruction using autologous stem/progenitor populations. Nevertheless, definitive evidence of the presence of stem cells in human auricular cartilage remains to be established. Here, we demonstrate that human auricular perichondrium, which can be obtained via a minimally invasive approach, harbors a unique cell population, termed as cartilage stem/progenitor cells (CSPCs). The clonogenic progeny of a single CD44(+) CD90(+) CSPC displays a number of features characteristic of stem cells. Highly chondrogenic CSPCs were shown to reconstruct large (>2 cm) elastic cartilage after extended expansion and differentiation. CSPC-derived cartilage was encapsulated by a perichondrium layer, which contains a CD44(+) CD90(+) self-renewing stem/progenitor population and was maintained without calcification or tumor formation even after 10 mo. This is a unique report demonstrating the presence of stem cells in auricular cartilage. Utilization of CSPCs will provide a promising reconstructive material for treating craniofacial defects with successful long-term tissue restoration.

Persistent malignant stem cells in del(5q) myelodysplasia in remission.

BACKGROUND: The in vivo clinical significance of malignant stem cells remains unclear. METHODS: Patients who have the 5q deletion (del[5q]) myelodysplastic syndrome (interstitial deletions involving the long arm of chromosome 5) have complete clinical and cytogenetic remissions in response to lenalidomide treatment, but they often have relapse. To determine whether the persistence of rare but distinct malignant stem cells accounts for such relapses, we examined bone marrow specimens obtained from seven patients with the del(5q) myelodysplastic syndrome who became transfusion-independent while receiving lenalidomide treatment and entered cytogenetic remission. RESULTS: Virtually all CD34+, CD38+ progenitor cells and stem cells that were positive for CD34 and CD90, with undetectable or low CD38 (CD38−/low), had the 5q deletion before treatment. Although lenalidomide efficiently reduced these progenitors in patients in complete remission, a larger fraction of the minor, quiescent, CD34+,CD38-/low, CD90+ del(5q) stem cells as well as functionally defined del(5q) stem cells remained distinctly resistant to lenalidomide. Over time, lenalidomide resistance developed in most of the patients in partial and complete remission, with recurrence or expansion of the del(5q) clone and clinical and cytogenetic progression. CONCLUSIONS: In these patients with the del(5q) myelodysplastic syndrome, we identified rare and phenotypically distinct del(5q) myelodysplastic syndrome stem cells that were also selectively resistant to therapeutic targeting at the time of complete clinical and cytogenetic remission. (Funded by the EuroCancerStemCell Consortium and others.)

Immunohistochemical staining, laser capture microdissection, and filter-aided sample preparation-assisted proteomic analysis of target cell populations within tissue samples.

An important problem involves isolating subpopulations of cells defined by protein markers in clinical tissue samples for proteomic studies. We describe a method termed Immunohistochemical staining, laser capture microdissection (LCM) and filter-aided sample preparation (FASP)-Assisted Proteomic analysis of Target cell populations within tissue samples (ILFAPT). The principle of ILFAPT is that a target cell population expressing a protein of interest can be lit up by immunohistochemical staining and isolated from tissue sections using LCM for FASP and proteomic analysis. Using this method, we isolated a small population of CD90(+) stem-like cells from glioblastoma multiforme tissue sections and identified 674 high-confidence (false discovery rate < 0.01) proteins from 32 nL of CD90(+) cells by LC-MS/MS using an Orbitrap Elite mass spectrometer. We further quantified the relative abundance of proteins identified from equal volumes of LCM-captured CD90(+) and CD90(-) cells, where 109 differentially expressed proteins were identified. The major group of these differentially expressed proteins was relevant to cell adhesion and cellular movement. This ILFAPT method has demonstrated the ability to provide in-depth proteome analysis of a very small specific cell population within tissues. It can be broadly applied to the study of target cell populations within clinical specimens.

Isolation of rabbit bone marrow mesenchymal stem cells using density gradient centrifugation and adherence screening methods.

AIM: Under special conditions, bone marrow mesenchymal stem cells (BMSCs) can differentiate into osteoblasts and chondroblasts. However, MSCs are few in bone marrow. How to harvest, purify and rapidly proliferate in vitro is a foundation of application in tissue engineering technique. To optimize, collect, purify, assess rabbit BMSCs and to observe the biological character of BMSCs. METHODS: Two female New Zealand rabbits aged 2 months were used for MSC collection and primary culture. Bone marrow solution was purified by density gradient centrifugation and adherence screening method. Culture solution was obtained. BMSCs were incubated in phosphate buffered solution (PBS), supplemented with 2.5 g/L trypsin (3.0 mL), and placed in an incubator at 37 °C for two or three minutes. Cell morphology was observed using an inverted microscope. The digestion was stopped when cytoplasm recovery, long and thin cells with large intercellular space, and few round cells appeared. Subsequently, BMSCs were incubated in serum-free L-DMEM, and placed in a plastic culture flask at 1.0×108/L. MSC morphology, ultrastructure and surface marker; proliferation of the first, third, fifth, eighth and tenth passages of BMSCs; cell growth curve was drawn. BMSCs was pure following density gradient centrifugation and adherence screening method. The third and fifth passage of cells had typical whirlpool-shape. RESULTS AND CONCLUSION: Transmission electron microscope demonstrated that round or oval MSCs possessed large nuclei, big nucleus proportion, a few cellular organ. These were low-differentiated cells. Growth curve of cultured MSCs was "S" shape. The first, third and fifth passage cells had strong reproductive capability. The eighth and tenth passage of cells had significantly reduced proliferation. Cells isolated were positive for CD44 and CD90, but negative for CD34. These were low-differentiated cells under the electron microscope. Isolated cells are MSCs, with the property of stem cells. The third and fifth passage cells are pure, with strong reproductive capability.

Microarray analysis of Dupuytren's disease cells: the profibrogenic role of the TGF-ß inducible p38 MAPK pathway.

BACKGROUND: Dupuytren's disease (DD) is a nodular palmar fibromatosis that causes irreversible permanent contracture of fingers and results in the loss of hand function. Surgery still remains the only available solution for DD patients but cannot permanently cure the disease nor reduce high recurrence rates. With this rationale, we designed a study aimed at an improved understanding of the molecular mechanisms underlying DD. Our major focus was an analysis of the global gene expression profile and signalling pathways in DD cells with the aim of identifying novel biomarkers and/or therapeutic targets. METHODS: Primary cells were cultured from surgically removed diseased and healthy tissue. Microarray expression analysis (HG-U133A array, Affymetrix) and qPCR was performed with total RNA isolated from primary DD cells. Mechanistic studies involving inhibition of p38 phosphorylation were performed on normal human fibroblasts' and primary DD cells' in vitro models. Expression of stem cell markers in primary fibroblasts/myofibroblasts was assessed as well. RESULTS: We identified 3 p38MAPK signalling pathway regulatory genes, THBS1, GADD45α and NUAK1, all involved in cellular proliferation and production of the extracellular matrix proteins. Inhibition of the p38MAPK signalling pathway induced down-regulation of myofibroblast markers, α-smooth muscle actin and palladin. A stem-cell like subpopulation positive for CD90 marker was identified among primary DD cells. CONCLUSION: The study reveals involvement of the p38 MAPK pathway as a possible signalling cascade in the pathogenesis of Dupuytren's disease. Moreover, a particular stem cell-like CD90(+) subpopulation was identified that might contribute to DD development.

NEUROG3 is a critical downstream effector for STAT3-regulated differentiation of mammalian stem and progenitor spermatogonia.

Spermatogenesis relies on coordinated differentiation of stem and progenitor spermatogonia, and the transcription factor STAT3 is essential for this process in mammals. Here we studied the THY1+ spermatogonial population in mouse testes, which contains spermatogonial stem cells (SSC) and non-stem cell progenitor spermatogonia, to further define the downstream mechanism regulating differentiation. Transcript abundance for the bHLH transcription factor Neurog3 was found to be significantly reduced upon transient inhibition of STAT3 signaling in these cells and exposure to GDNF, a key growth factor regulating self-renewal of SSCs, suppressed activation of STAT3 and in accordance Neurog3 gene expression. Moreover, STAT3 was found to bind the distal Neurog3 promoter/enhancer region in THY1+ spermatogonia and regulate transcription. Transient inhibition of Neurog3 expression in cultures of proliferating THY1+ spermatogonia increased stem cell content after several self-renewal cycles without effecting overall proliferation of the cells, indicating impaired differentiation of SSCs to produce progenitor spermatogonia. Furthermore, cultured THY1+ spermatogonia with induced deficiency of Neurog3 were found to be incapable of differentiation in vivo following transplantation into testes of recipient mice. Collectively, these results establish a mechanism by which activation of STAT3 regulates the expression of NEUROG3 to subsequently drive differentiation of SSC and progenitor spermatogonia in the mammalian germline.

Differential expression of CD90 and CD14 stem cell markers in malignant breast cancer cell lines.

The recently emerged concept of cancer stem cell (CSC) has led to a new hypothesis on the basis for tumor progression. Basically, the CSC theory hypothesizes the presence of a hierarchically organized and relatively rare cell population, which is responsible for tumor initiation, self-renewal, and maintenance, in addition to accumulation of mutation and resistance to chemotherapy. CSCs have recently been described in breast cancer. Different genetic markers have been used to isolate breast CSCs, none of which have been correlated with the tumorigenicity or metastatic potential of the cells, limiting their precise characterization and clinical application in the development of therapeutic protocols. Here, we sought for subpopulations of CSCs by analyzing 10 judiciously chosen stem cell markers in a normal breast cell line (MCF10-A) and in four human breast cancer cell lines (MCF-7, MDA-MB-231, MDA-MB-435, and Hs578-T) displaying different degrees of metastatic and invasiveness potential. We were able to identify two markers, which are differentially expressed in nontumorigenic versus tumor cells. The CD90 marker was highly expressed in the malignant cell lines. Interestingly, the CD14 molecule displayed higher expression levels in the nontumorigenic cell line. Therefore, we demonstrated that these two markers, which are more commonly used to isolate and characterize stem cells, are differentially expressed in breast tumor cells, when compared with nontumorigenic breast cells.

Human endometrial stem cell neurogenesis in response to NGF and bFGF.

The potential of cell therapy is promising in nerve regeneration, but is limited by ethical considerations about the proper and technically safe source of stem cells. We report the successful differentiation of human EnSCs (endometrial stem cells) as a rich source of renewable and safe progenitors into high-efficiency cholinergic neurons. The extracellular signals of NGF (nerve growth factor) and bFGF (basic fibroblast growth factor) could induce cholinergic neuron differentiation. ChAT (choline acetyltransferase), MAP2 (microtubule associated protein 2) and NF-l (neurofilament L) increased after administration of bFGF and NGF to the EnSC cultures. trkC and FGFR2 (fibroblast growth factor receptor 2), which belong to the NGF and bFGF receptors respectively, were determined in populations of EnSCs. NGF, bFGF and their combination differentially influenced human EnSCs high efficiency differentiation. By inducing cholinergic neurons from EnSCs in a chemically defined medium, we could produce human neural cells without resorting to primary culture of neurons. This in vitro method provides an unlimited source of human neural cells and facilitates clinical applications of EnSCs for neurological diseases.

Human intraoral harvested mesenchymal stem cells: characterization, multilineage differentiation analysis, and 3-dimensional migration of natural bone mineral and tricalcium phosphate scaffolds.

PURPOSE: The aim of this study was the establishment of a minimally invasive technique of mesenchymal stem cell (MSC) harvesting and a predictable isolation and cultivation method on 2 different bone substitutes used as potential scaffolds. MATERIALS AND METHODS: Human MSCs isolated from the posterior maxilla were characterized by flow cytometric analysis. After in vitro expansion, cells were cultured and differentiated toward osteogenic, adipogenic, and chondrogenic lineages in 2-dimensional cultures and on natural bone mineral of bovine origin and ß-tricalcium phosphate scaffolds. Three-dimensional growth was analyzed using live cell staining and confocal laser scanning microscopy. RESULTS: MSCs from all patients demonstrated the same immunophenotype, with expression of CD73, CD90, and CD105 but no expression of CD45, CD34, CD14, CD11, and HLA-DR. The potential of MSCs for multilineage differentiation along osteogenic, adipogenic, and chondrogenic lines was shown. Based on knowledge of the characteristics of the cells, a method was established to increase MSC expansion efficiency and seeding conditions on each scaffold. Results of the in vitro characterization and laser scanning microscopy visualized the 3-dimensional growth of MSCs on the 2 scaffold types. CONCLUSIONS: The present data showed that intraoral MSCs can be cultured predictably under 2- and 3-dimensional conditions, have proved multiple potencies, and thus seem to be potential candidates for tissue engineering approaches in maxillofacial reconstructions.

Isolating stromal stem cells from periodontal granulation tissues.

Stem cell therapy is a promising area in regenerative medicine. Periodontal granulation tissues are often discarded during conventional surgery. If stromal stem cells can be isolated from these tissues, they can be used for subsequent surgery on the same patient. Fifteen human periodontal granulation tissue samples were obtained from intrabony defects during surgery. Immunohistochemistry (IHC) was carried out on five of the samples to identify STRO-1, a marker of mesenchymal stem cells. Five samples underwent flow cytometry analysis for the same marker. The remaining five samples were characterized by "colony formation unit-fibroblast" (CFU-f) assay and selected for proliferation assay, flow cytometry of stem cell markers, immunocytochemistry (ICC), multipotent differentiation assays, and repairing critical-size defects in mice. The ratio of STRO-1(+) cells detected by IHC was 5.91 ± 1.50%. The analysis of flow cytometry for STRO-1 was 6.70 ± 0.81%. Approximately two thirds of the CFU-f colonies had a strong reaction to STRO-1 in ICC staining. The cells were multipotent both in vitro and in vivo. Mice given bone grafts and stem cells showed significantly better bone healing than those without stem cells. Multipotent stromal stem cells can be isolated from human periodontal granulation tissues. These cells improve new bone formation when transplanted in mouse calvarial defects. Isolating stem cells from relatively accessible sites without extra procedures is clinically advantageous. This study demonstrated that human periodontal granulation tissues contain isolatable multipotent stem cells. The cells may be a good source for autotransplantation in subsequent treatment.

Peripheral Nerve Sheath Tumors in Patients With Neurofibromatosis Type 1: Morphological and Immunohistochemical Study.

BACKGROUND/AIM: The aim of the present investigation was to characterize the growth pattern and antigen profile of peripheral nerve sheath tumors (PNST) in a large series of tumors obtained from patients with Neurofibromatosis type 1 (NF1) focusing on morphological characteristics of diffuse plexiform neurofibroma (DPNF). MATERIALS AND METHODS: Tissue micro-array (TMA) analysis was applied to study 520 formalin-fixed, paraffin-embedded human PNST of 385 patients with confirmed NF1 diagnosis. PNST originated from all areas of the body and were classified as cutaneous neurofibroma (CNF, n=114), diffuse neurofibroma (DNF, n=109), DPNF (n=108), plexiform neurofibroma (PNF, n=110), and malignant peripheral nerve sheath tumor (MPNST, n=22). Histomorphology and antigen expression patterns of the tumors were determined [S100, epithelial membrane antigen (EMA), CD90, mast cell tryptase, and neurofilament]. RESULTS: Benign PNST showed significantly more S100-positive tumor cells than MPNST (p<0.001). EMA expression was most pronounced in perineurium of DPNF. The number of mast cells in CNF, DNF and DPNF was significantly higher compared to PNF and MPNST (p<0.001 for both comparisons, Mann-Whitney U-test). CONCLUSION: DPNF show some distinct cellular characteristics. A high number of EMA positive cells possibly indicates the dissemination of perineural cells to the surrounding tissue. Concerning mast cell density, DPNF resemble DNF and CNS rather than PNF. Close contact of tumor cells in DPNF, DNF and CNF with the immune system is a prerequisite for permanent immunological reactions in contrast to PNF in which tumor cells are partitioned from the immune system by the perineurium and blood-nerve barrier of blood vessels. It is assumed that these morphological distinctions may reflect in part the biological differences between the entities. While PNF is a known precancerous stage in NF1 patients, DPNF are not rated as such. Furthermore, the morphologic differences between benign nerve sheath tumors may be important for the efficacy of drugs to access tumor cells.