Biocompatibility of bone graft substitutes: effects on survival and proliferation of porcine multilineage stem cells in vitro

Bone graft substitutes (BGS) are widely used in clinical practice. For stem cellbased approaches to bone tissue engineering BGS need to show sufficient biocompatibility in the in vitro setting. This study was designed to demonstrate the influence of six different BGS on the proliferation and metabolic activity of porcine mesenchymal multilineage stem cells (pMSC) in vitro. Bone-marrow derived pMSC were cultivated for 24 hours with the eluates of six different BGS. The eluates were generated by incubating the BGS three times in succession for 24 hours with a culture medium and collecting the supernatants. pMSC vitality and proliferation in the presence of eluates from the first, second, and third incubation were assessed by WST-test quantification of metabolically active cells. Culture of pMSC with eluates in all cases resulted in decreased cell numbers in an eluate concentration-dependent manner. At least a 65% loss of cells compared to controls (culture medium without eluates) could be observed in the presence of undiluted eluates. The negative influence of eluates varied significantly among BGS. In all cases, second and third eluates were less potent in their negative effects on cellular vitality/proliferation. In conclusion, the BGS examined here should be submitted to thorough preincubation before in vitro use for cell-based constructs to maximize cell viability for the tissue engineering of bone. (Folia Morphol 2011; 70, 3: 154–160

Increased survival rate by local release of diclofenac in a murine model of recurrent oral carcinoma

Olga Maria Will,1,* Nicolai Purcz,2,* Athena Chalaris,3 Carola Heneweer,4,5 Susann Boretius,1 Larissa Purcz,2 Lila Nikkola,6 Nureddin Ashammakhi,6 Holger Kalthoff,7 Claus-Christian Glüer,1 Jörg Wiltfang,2 Yahya Açil,2 Sanjay Tiwari1 1Section Biomedical Imaging, Clinic for Radiology and Neuroradiology, MOIN CC, 2Department of Oral and Maxillofacial Surgery, University Hospital Schleswig-Holstein, 3Institute of Biochemistry, Christian-Albrechts-Universität zu Kiel, 4Clinic for Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Kiel, 5Institute for Diagnostic and Interventional Radiology, University Hospital Cologne, Cologne, Germany; 6Department of Biomedical Engineering, Tampere University of Technology, Tampere, Finland; 7Institute for Experimental Cancer Research, University Hospital Schleswig-Holstein, Kiel, Germany *These authors contributed equally to this work Abstract: Despite aggressive treatment with radiation and combination chemotherapy following tumor resection, the 5-year survival rate for patients with head and neck cancer is at best only 50%. In this study, we examined the therapeutic potential of localized release of diclofenac from electrospun nanofibers generated from poly(d,l-lactide-co-glycolide) polymer. Diclofenac was chosen since anti-inflammatory agents that inhibit cyclooxygenase have shown great potential in their ability to directly inhibit tumor growth as well as suppress inflammation-mediated tumor growth. A mouse resection model of oral carcinoma was developed by establishing tumor growth in the oral cavity by ultrasound-guided injection of 1 million SCC-9 cells in the floor of the mouth. Following resection, mice were allocated into four groups with the following treatment: 1) no treatment, 2) implanted scaffolds without diclofenac, 3) implanted scaffolds loaded with diclofenac, and 4) diclofenac given orally. Small animal ultrasound and magnetic resonance imaging were utilized for longitudinal determination of tumor recurrence. At the end of 7 weeks following tumor resection, 33% of mice with diclofenac-loaded scaffolds had a recurrent tumor, in comparison to 90%–100% of the mice in the other three groups. At this time point, mice with diclofenac-releasing scaffolds showed 89% survival rate, while the other groups showed survival rates of 10%–25%. Immunohistochemical staining of recurrent tumors revealed a near 10-fold decrease in the proliferation marker Ki-67 in the tumors derived from mice with diclofenac-releasing scaffolds. In summary, the local application of diclofenac in an orthotopic mouse tumor resection model of oral cancer reduced tumor recurrence with significant improvement in survival over a 7-week study period following tumor resection. Local drug release of anti-inflammatory agents should be investigated as a therapeutic option in the prevention of tumor recurrence in oral squamous carcinoma. Keywords: tumor recurrence, oral squamous cell carcinoma, head and neck cancer, NSAIDs, drug releasing polymers, mouse model&nbsp