Nikolaos Zogas

Mesenchymal stem cells are conditionally therapeutic in preclinical models of rheumatoid arthritis

Objective The role of mesenchymal stem cells (MSC) in experimental arthritis is undoubtedly conflicting. This study explored the effect of bone marrow-derived MSC in previously untested and pathogenetically different models of rheumatoid arthritis (RA). Methods MSC were tested both in an induced (adjuvant-induced) and a spontaneous (K/BxN) arthritis model. Arthritis was assessed clinically and histologically. The proliferation of splenocytes and fibroblast-like synoviocytes (FLS) in the presence of MSC was measured by radioactivity incorporation. Toll-like receptor (TLR) expression was measured by real-time PCR. T-regulatory cell (Treg) frequency, T-cell apoptosis and cytokine secretion were monitored by flow cytometry. Results MSC, in vitro, strongly inhibited critical cell populations; splenocytes and FLS. In contrast, MSC proved ineffective in vivo, unless they were administered before disease onset, an effect implying that the inflammatory arthritic milieu potentially abrogates MSC immunomodulatory properties. In order to alleviate inflammation before MSC infusion, the authors administered, at arthritis onset, a short course with a proteasome inhibitor, bortezomib, whereas MSC were infused when established disease was expected. The bortezomib plus MSC group demonstrated a significantly decreased arthritis score over arthritic, MSC-only, bortezomib-only groups, also confirmed by histology and immunohistochemistry. The bortezomib plus MSC combination restored TLR expression and Treg frequency in blood and normalised FLS and splenocyte proliferation, apoptosis and cytokine secretion. Conclusion MSC lose their immunomodulatory properties when infused in the inflammatory micromilieu of autoimmune arthritis. Conditioning of the recipient with bortezomib alters the disease microenvironment enabling MSC to modulate arthritis. Should milieu limitations also operate in human disease, this approach could serve as a strategy to treat RA by MSC.

Plerixafor+G-CSF–mobilized CD34+ cells represent an optimal graft source for thalassemia gene therapy

Globin gene therapy requires abundant numbers of highly engraftable, autologous hematopoietic stem cells expressing curative levels of β-globin on differentiation. In this study, CD34+ cells from 31 thalassemic patients mobilized with hydroxyurea+granulocyte colony-stimulating factor (G-CSF), G-CSF, Plerixafor, or Plerixafor+G-CSF were transduced with the TNS9.3.55 β-globin lentivector and compared for transducibility and globin expression in vitro, as well as engraftment potential in a xenogeneic model after partial myeloablation. Transduction efficiency and vector copy number (VCN) averaged 48.4 ± 2.8% and 1.91 ± 0.04, respectively, whereas expression approximated the one-copy normal β-globin output. Plerixafor+G-CSF cells produced the highest β-globin expression/VCN. Long-term multilineage engraftment and persistent VCN and vector expression was encountered in all xenografted groups, with Plerixafor+G-CSF-mobilized cells achieving superior short-term engraftment rates, with similar numbers of CD34+ cells transplanted. Overall, Plerixafor+G-CSF not only allows high CD34+ cell yields but also provides increased β-globin expression/VCN and enhanced early human chimerism under nonmyeloablative conditions, thus representing an optimal graft for thalassemia gene therapy.

Hematopoietic stem cells and liver regeneration: Differentially acting hematopoietic stem cell mobilization agents reverse induced chronic liver injury

Bone marrow (BM) could serve as a source of cells facilitating liver repopulation in case of hepatic damage. Currently available hematopoietic stem cell (HSC) mobilizing agents, were comparatively tested for healing potential in liver fibrosis. Carbon tetrachloride (CCl4)-injured mice previously reconstituted with Green Fluorescent Protein BM were mobilized with Granulocyte-Colony Stimulating Factor (G-CSF), Plerixafor or G-CSF+Plerixafor. Hepatic fibrosis, stellate cell activation and oval stem cell frequency were measured by Gomori and by immunohistochemistry for a-Smooth Muscle Actin and Cytokeratin-19, respectively. Angiogenesis was evaluated by ELISA and immunohistochemistry. Quantitative real-time PCR was used to determine the mRNA levels of liver Peroxisome Proliferator-Activated Receptor gamma (PPAR-γ), Interleukin-6 (IL-6) and Tumor Necrosis-alpha (TNFα). BM-derived cells were tracked by double immunofluorescence. The spontaneous migration of mobilized HSCs towards injured liver and its cytokine secretion profile was determined in transwell culture systems. Either single-agent mobilization or the combination of agents significantly ameliorated hepatic damage by decreasing fibrosis and restoring the abnormal vascular network in the liver of mobilized mice compared to CCl4-only mice. The degree of fibrosis reduction was similar among all mobilized mice despite that G-CSF+Plerixafor yielded significantly higher numbers of circulating HSCs over other agents. The liver homing potential of variously mobilized HSCs differed among the agents. An extended G-CSF treatment provided the highest anti-fibrotic effect over all tested modalities, induced by the proliferation of hepatic stem cells and decreased hepatic inflammation. Plerixafor-mobilized HSCs, despite their reduced liver homing potential, reversed fibrosis mainly by increasing hepatic PPAR-γ and VEGF expression. In all groups, BM-derived mature hepatocytes as well as liver-committed BM stem cells were detected only at low frequencies, further supporting the concept that alternative mechanisms rather than direct HSC effects regulate liver recovery. Overall, our data suggest that G-CSF, Plerixafor and G-CSF+Plerixafor act differentially during the wound healing process, ultimately providing a potent anti-fibrotic effect.

Prospects of Gene Therapy for Pulmonary Diseases: Progress and Limitations

BACKGROUND Despite the proof of principle that gene therapy can cure various monogenic diseases, limited clinical progress has been noted for gene therapy of the respiratory system. Certain anatomic features of the lungs, along with the suboptimal gene delivery vehicles utilized up to now, have significantly delayed successful clinical practice. Thus, the need for additional improvements towards safety and efficacy of the procedure is indispensable. OBJECTIVE The objective of this work was to review the progress and limitations of gene therapy in the treatment of lung disease with a focus on monogenic disease, chronic obstructive pulmonary disease and asthma and to present studies that provide a proof of principle that it works in different model systems and in patients. METHOD A thorough search was performed on the aforementioned topic using Pubmed in order to identify relevant manuscripts. Several gene therapy studies for monogenic disorders affecting other organs or systems were also taken into consideration. RESULTS A hundred and thirty one papers were included. Inclusion criteria regarded novel gene transfer technologies of the past decade, as well as publications outlining the pitfalls that precluded earlier successful implementation of gene therapy for pulmonary diseases. CONCLUSION Current gene transfer protocols and vector design require additional amelioration. The rapidly evolving and much promising technology of CRISPR/Cas9 might possibly overcome the hurdles posed to date for effective implementation of gene therapy and become the basis for the onset of new clinical trials.

AB062. COX-2 inhibitors, a potential synergistic effect with antineoplastic drugs in lung cancer

Background: Lung cancer represents the leading cause of cancer-related deaths worldwide and novel therapeutic approaches targeting crucial pathways are urgently needed to improve its treatment. Inflammation plays a critical role in multistage tumor development and increased evidence has supported the involvement of cyclooxygenase-2 expression in carcinogenesis. We investigated the potential use of COX-2 inhibitors in cancer proliferation and apoptosis. Methods: Celecoxib, rofecoxib, etoricoxib, meloxicam, ibufrofen and indomethacin are the COX-2 inhibitors included in this study. Docetaxel and Cisplatin are the chemotherapeutic agents that we combined with COX-2 inhibitors. Lung cancer cell lines (NCI-H1048-Small cell lung cancer, A549Non-small cell lung cancer) were purchased from ATCC LGC Standards. At indicated time-point, following 24h and 48h incubation, cell viability and apoptosis were measured with Annexin V staining by flow cytometry. Statistical analysis was performed by GraphPad Prism. Results: In Small cell lung cancer cells, following 24h incubation, combinations of docetaxel and meloxicam, docetaxel and ibuprofen, docetaxel and indomethacin, showed increased apoptosis when compared to docetaxel alone (p<0.0001). In Non-small cell lung cancer cells, the 24h incubation was not enough to induce satisfactory apoptosis, but following 48h incubation, docetaxel plus indomethacin showed more cytotoxicity when compared to docetaxel alone (p<0.0001). In addition, the combination of cisplatin plus indomethacin was the only combination to be found with higher cytotoxicity when compared to cisplatin alone after 48h treatment (p<0.0001). Conclusion: Depending on the drug, the synergistic effect of COX-2 inhibitors plus chemotherapeutic agents has been demonstrated in lung cancer. Our suggestion is that COX-2 inhibitors could be used as additive and maintenance treatment in combination to antineoplastic agents in lung cancer patients.