The Effect of Recombinant Tyrosine Hydroxylase Expression on the Neurogenic Differentiation Potency of Mesenchymal Stem Cells.

OBJECTIVE: Tyrosine hydroxylase (TH) is a rate-limiting enzyme in dopamine synthesis, making the enhancement of its activity a target for ensuring sufficient dopamine levels. Rat bone marrow mesenchymal stem cells (rBM-MSCs) are known to synthesize TH after differentiating into neuronal cells through chemical induction, but the effect of its ectopic expression on these cells has not yet been determined. This study investigated the effects of ectopic recombinant TH expression on the stemness characteristics of rBM-MSCs. METHODS: After cloning, a cell line with stable TH expression was maintained, and the proliferation, the gene expression profile, and differentiation potential of rBM-MSCs were analyzed. Analysis of the cells showed an increment in the proliferation rate that could be reversed by the neutralization of TH. RESULTS: The constitutive expression of TH in rBM-MSCs was successfully implemented, without significantly affecting their osteogenic and adipogenic differentiation potential. TH expression improved the expression of other neuronal markers, such as glial fibrillary acidic protein, ß-tubulin, nestin, and c-Fos, confirming the neurogenic differentiation capacity of the stem cells. The expression of brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF) significantly increased after the chemical induction of neurogenic differentiation. CONCLUSION: In this study, the expression of recombinant TH improved the neuroprotective effect of MSCs by upregulating the expression of BDNF and CNTF. Although the neuronal markers were upregulated, the expression of recombinant TH alone in rBM-MSCs was not sufficient for MSCs to differentiate into neurogenic cell lines.

Comparison of Different Sources of Mesenchymal Stem Cells: Palatal versus Lipoaspirated Adipose Tissue.

OBJECTIVES: The purpose of this study was to compare the proliferation and differentiation potential of mesenchymal stem cells (MSCs) derived from palatal adipose tissue (PAT) and lipoaspirated adipose tissue (LAT). MATERIALS AND METHODS: PATs were obtained from 2 healthy female patients undergoing surgery for gingival recession, and LATs were obtained from 2 healthy female patients undergoing plastic surgery. LAT- and PAT-derived MSCs were confirmed by flow cytometry using MSC-specific surface markers. The multilineage differentiation capacity of the MSCs was analyzed. The expression of immunophenotyping, embryonic, and differentiation markers was compared between both MSC lines. The proliferation of PAT- and LAT-MSCs was evaluated using a real-time cell analyzer, and telomerase activity was determined using an ELISA-based TRAP assay. Stem cells isolated from PAT and LAT were analyzed by real-time PCR and whole genome array analysis. RESULTS: The cells isolated from PAT had MSC characteristics. In addition, PAT-MSCs had significantly higher alkaline phosphatase activity and osteogenic potential than LAT-MSCs. Although the proliferation and telomerase activities of LAT-MSCs were higher than those of PAT-MSCs, the difference was not statistically significant. The level of embryonic stem cell markers (Oct4 and Nanog) was higher in LAT-MSCs than in PAT-MSCs. The whole genome array analysis demonstrated that 255 gene sequences were differentially expressed, with more than a twofold change in expression. CONCLUSIONS: This is the first comparative analysis of the isolation and characterization of MSCs from PAT and LAT. PAT is an accessible source of MSCs, which could be used in periodontal and craniofacial tissue engineering.

Comparison of mesenchymal stem cells isolated from pulp and periodontal ligament.

BACKGROUND: Cell-based therapy using mesenchymal stem cells (MSCs) seems promising to obtain regeneration of dental tissues. A comparison of tissue sources, including periodontal ligament (PDL) versus pulp (P), could provide critical information to select an appropriate MSC population for designing predictable regenerative therapies. The purpose of this study is to compare the proliferation and stemness and the MSC-specific and mineralized tissue-specific gene expression of P-MSCs and PDL-MSCs. METHODS: MSCs were obtained from PDL and P tissue of premolars (n = 3) extracted for orthodontic reasons. MSC proliferation was evaluated using a real-time cell analyzer for 160 hours. Telomerase activity was evaluated by a telomeric repeat amplification protocol assay based on enzyme-linked immunosorbent assay. Total RNA was isolated from the MSCs on day 3. A polymerase chain reaction (PCR) array was used to compare the expression of MSC-specific genes. The expression of mineralized tissue-associated genes, including Type I collagen (COL I), runt-related transcription factor 2 (RunX2), bone sialoprotein (BSP), and osteocalcin (OCN) messenger RNA (mRNA), was evaluated using quantitative real-time PCR. RESULTS: Higher proliferation potential and telomerase activity were observed in the P-MSCs compared to PDL-MSCs of premolar teeth. Fourteen of 84 genes related to MSCs were expressed differently in the PDL-MSCs versus the P-MSCs. The expressions of bone morphogenetic protein 2 (BMP2) and BMP6; sex-determining region Y-box 9 (SOX9); integrin, alpha 6 (ITGA6); melanoma cell adhesion molecule (MCAM); phosphatidylinositol glycan anchor biosynthesis, class S (PIGS); prominin 1 (PROM1); ribosomal protein L13A (RPL13A); and microphthalmia-associated transcription factor (MITF) were higher in the P-MSCs compared to the PDL-MSCs, and higher expression of matrix metalloproteinase 2 (MMP2), interleukin (IL)-6, insulin (INS), alanyl (membrane) aminopeptidase (ANPEP), and IL-10 were observed in the PDL-MSCs. However, there was no statistically significant difference in the expression of mineralized tissue-associated genes, including BSP and RunX2, between the P-MSCs and the PDL-MSCs. Higher expression of COL I and lower expression of OCN mRNA transcripts were noted in the PDL-MSCs compared to the P-MSCs. CONCLUSIONS: The results of this study suggest that MSCs isolated from P and PDL tissues show different cellular behavior. To increase the predictability of MSC-based regenerative treatment, differences in dental tissue-derived MSCs and favorable aspects of cell sources should be further clarified.

Bone morphogenetic protein-2, -6, and -7 differently regulate osteogenic differentiation of human periodontal ligament stem cells.

The utility of adult stem cells for bone regeneration may be an attractive alternative in the treatment of extensive injury, congenital malformations, or diseases causing large bone defects. To create an environment that is supportive of bone formation, signals from molecules such as the bone morphogenetic proteins (BMPs) are required to engineer fully viable and functional bone. We therefore determined whether BMP-2, -6, and -7 differentially regulate the (1) proliferation, (2) mineralization, and (3) mRNA expression of bone/mineralized tissue associated genes of human periodontal ligament stem cells (hPDLSCs), which were obtained from periodontal ligament tissue of human impacted third molars. hPDLSCs from six participants were isolated and characterized using histochemical and immunohistochemical methods. A real-time cell analyzer was used to evaluate the effects of BMP-2, -6, and -7 on the proliferation of hPDLSCs. hPDLSCs were treated with Dulbecco's modified Eagle's medium containing different concentrations of BMP-2, -6, and -7 (10, 25, 50, 100 ng/mL) and monitored for 264 hours. After dose-response experiments, 50 and 100 ng/mL concentrations of BMPs were used to measure bone/mineralized tissue-associated gene expression. Type I collagen, bone sialoprotein, osteocalcin, osteopontin, and osteoblastic transcription factor Runx2 mRNA expression of hPDLSCs treated with BMP-2, -6, and -7, were evaluated using quantitative RT-PCR. Biomineralization of hPDLSCs was assessed using von Kossa staining. This study demonstrated that BMPs at various concentrations differently regulate the proliferation, mineralization, and mRNA expression of bone/mineralized tissue associated genes in hPDLSCs. BMPs regulate hPDLSC proliferation in a time and dose-dependent manner when compared to an untreated control group. BMPs induced bone/mineralized tissue-associated gene mRNA expression and biomineralization of hPDLSCs. The most pronounced induction occurred in the BMP-6 group in the biomineralization of the hPDLSCs. Our data suggest that BMP-2, -6, and -7 are potent regulators of hPDLSC gene expression and biomineralization. Employing BMPs with hPDLSCs isolated from periodontal ligament tissues provides a promising strategy for bone tissue engineering.

Combined flow cytometric analysis of surface and intracellular antigens reveals surface molecule markers of human neuropoiesis.

Surface molecule profiles undergo dynamic changes in physiology and pathology, serve as markers of cellular state and phenotype and can be exploited for cell selection strategies and diagnostics. The isolation of well-defined cell subsets is needed for in vivo and in vitro applications in stem cell biology. In this technical report, we present an approach for defining a subset of interest in a mixed cell population by flow cytometric detection of intracellular antigens. We have developed a fully validated protocol that enables the co-detection of cluster of differentiation (CD) surface antigens on fixed, permeabilized neural cell populations defined by intracellular staining. Determining the degree of co-expression of surface marker candidates with intracellular target population markers (nestin, MAP2, doublecortin, TUJ1) on neuroblastoma cell lines (SH-SY5Y, BE(2)-M17) yielded a combinatorial CD49f(-)/CD200(high) surface marker panel. Its application in fluorescence-activated cell sorting (FACS) generated enriched neuronal cultures from differentiated cell suspensions derived from human induced pluripotent stem cells. Our data underlines the feasibility of using the described co-labeling protocol and co-expression analysis for quantitative assays in mammalian neurobiology and for screening approaches to identify much needed surface markers in stem cell biology.