Plasmid pRSVL persisted and expressed luciferase for at least 19 months in mouse skeletal muscle after intramuscular injection. Other injected plasmids also stably expressed long-term suggesting that any plasmid DNA could stably persist and express in muscle. Plasmid DNA was demonstrated by quantitative PCR in some of the muscle DNA samples for at least 19 months after injection. The methylation pattern of the plasmid DNA remained in its bacterial form indicating that the foreign DNA did not replicate in the muscle cells. The electroporation of total cellular DNA from injected muscles into bacteria indicated that the plasmid DNA was extrachromosomal. Chromosomal integration of plasmid DNA was searched for by electroporating the injected muscle DNA into bacteria after restriction enzyme digestion and ligation. No plasmids containing plasmid/chromosome junctions were observed in over 1800 colonies examined. Lack of integration increases the theoretical safety of this gene transfer technique. Long-term stability of plasmid DNA in muscle indicates that muscle is an attractive target tissue for the introduction of extrachromosomal plasmid or viral DNA for the purpose of gene therapy.

Very long term persistence of plasmid dna and foreign gene expression in mouse muscle

Mesenchymal stem cells (MSCs) are multipotent cells that are being clinically explored as a new therapeutic for treating a variety of immune-mediated diseases. First heralded as a regenerative therapy for skeletal tissue repair, MSCs have recently been shown to modulate endogenous tissue and immune cells. Preclinical studies of the mechanism of action suggest that the therapeutic effects afforded by MSC transplantation are short-lived and related to dynamic, paracrine interactions between MSCs and host cells. Therefore, representations of MSCs as drug-loaded particles may allow for pharmacokinetic models to predict the therapeutic activity of MSC transplants as a function of drug delivery mode. By integrating principles of MSC biology, therapy, and engineering, the field is armed to usher in the next generation of stem cell therapeutics.

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Mesenchymal Stem Cells as Therapeutics

PDGF, TGF-beta, and FGF signaling is important for differentiation and growth of mesenchymal stem cells (MSCs): transcriptional profiling can identify markers and signaling pathways important in differentiation of MSCs into adipogenic, chondrogenic, and osteogenic lineages.

Human platelet lysate can replace fetal bovine serum for clinical-scale expansion of functional mesenchymal stromal cells.

In this study, we used a common procedure to assess the potential of mobilized peripheral blood (MPB) and umbilical cord blood (UCB) as sources of mesenchymal stem cells (MSCs) in comparison with bone marrow (BM). We tested three methods: plastic adhesion supplemented with 5% of BM-MSC conditioned medium, unsupplemented plastic adhesion, and selection of CD133-positive cells. MSCs derived from MPB or UCB are identified by their positive expression of mesenchymal (SH2, SH3) and negative expression of hematopoietic markers (CD14, CD34, CD45, HLA-DR). We observed that the CD133-positive cell fraction contains more MSCs with high proliferative potential. Placed in appropriate conditions, these cells proved their capacity to differentiate into adipocytes, osteocytes, chondrocytes, and neuronal/glial cells. MPB- and UCB-MSCs express Oct4, a transcriptional binding factor present in undifferentiated cells with high proliferative capacity. The selection of CD133-positive cells enabled us to obtain a homogeneous population of MSCs from UCB and MPB. These sources may have a major clinical importance thanks to their easy accessibility.

https://stemcellsjournals.onlinelibrary.wiley.com/doi/pdf/10.1634/stemcells.2004-0330

Mesenchymal stem cells derived from CD133-positive cells in mobilized peripheral blood and cord blood: proliferation, Oct4 expression, and plasticity.

Comparison of immunomodulatory properties of mesenchymal stem cells derived from adult human tissues

Gastric adenocarcinoma is one of the most common malignancies in the world, and yet little is known about its molecular process of development and progression. Recent studies have suggested that ingestion of nonsteroid anti-inflammatory drugs reduces the risk of colon cancer, presumably by inhibiting the cyclooxygenase (COX) enzyme. COX-2, one isoform of the COX enzyme, is the rate-limiting enzyme in prostaglandin synthesis, and the function of this enzyme is thought to relate to inflammatory processes and carcinogenesis. To understand the role of COX enzyme in gastric cancer, we measured COX-2 expression in 104 human gastric carcinoma tissues by immunohistochemical analysis. We obtained tissue specimens from 104 surgically resected gastric adenocarcinoma patients. We performed immunohistochemical stain for human COX-2 with polyclonal antibody in gastric carcinoma. After curative resection and extensive lymph node dissection, all patients received adjuvant chemotherapy containing 5-fluorouracil. Expression of COX-2 showed cytoplasmic staining, not only in cancer cells but also in precancerous lesions such as metaplastic and adenomatous cells. We confirmed up-regulation of COX-2 in gastric cancer tissues compared with normal paired mucosa using Western blot analysis. There was no correlation between clinicopathological characteristics of gastric cancer patients and intensity of COX-2 protein expression. This study indicates that COX-2 protein over-expression may contribute to an early event of gastric cancer development, and it further suggests that selective inhibition of COX-2 may provide a chemopreventive effect against gastric carcinogenesis.

https://clincancerres.aacrjournals.org/content/clincanres/6/2/519.full.pdf

Increased expression of cyclooxygenase-2 protein in human gastric carcinoma.

Mesenchymal stem cells from cryopreserved human umbilical cord blood.

Umbilical cord blood (UCB) is well known to be a rich source of hematopoietic stem cells with practical and ethical advantages. Because mesenchymal stem cells (MSCs) from bone marrow have been regarded as good materials for cell/gene therapy as well as for tissue engineering because of their multidifferentiation potential, a number of trials have been undertaken to isolate MSCs from UCB. However, the results have been controversial, and little has become known about the effect of cryopreservation on the isolation of these stem cells. In this study, we examined the ability of cryopreserved UCB-derived cells to produce MSCs.Various culture conditions, including the seeding concentrations of cells and the media used, were investigated. We were able to obtain adherent cell populations after 3 to 5 weeks in our culture conditions from UCB-derived mononuclear cell fractions that had undergone cryopreservation for 0.1 to 5 years.These cells exhibited a fibroblast-like morphology and typical mesenchymal-like immunophenotypes.The results indicate that cryopreserved human UCB fractions can be used as an alternative source of MSCs for experimental and clinical applications as well as for tissue engineering.

Mal Sook Yang

Papers

Comparison of immunomodulatory properties of mesenchymal stem cells derived from adult human tissues

Increased expression of cyclooxygenase-2 protein in human gastric carcinoma.

Mesenchymal stem cells from cryopreserved human umbilical cord blood.

Isolation of Mesenchymal Stem Cells from Cryopreserved Human Umbilical Cord Blood

Neural differentiation of novel multipotent progenitor cells from cryopreserved human umbilical cord blood.