Search

Objectives: The aim of this study was to select and provide enough stem cells for quick transplantation in bone engineering procedures, avoiding any in vitro expansion step. Materials and Methods: Dental germ pulp, collected from 25 healthy subjects aged 13–20 years, were subjected to magnetic‐activated cell sorting to select a CD34(+) stem cell population capable of differentiating into pre‐osteoblasts. These cells were allowed to adhere to an absorbable polylactic–coglycolic acid scaffold for 30 min, without any prior expansion, and the CD34(+) cell‐colonized scaffolds were then transplanted into immunocompromised rats, subcutaneously. Results: After 60 days, analysis of recovered transplants revealed that they were formed of nodules of bone, of the same dimensions as the original scaffold. Bone‐specific proteins were detected by immunofluorescence, within the nodules, and X‐ray diffraction patterns revealed characteristic features of bone. In addition, presence of platelet endothelial cell adhesion molecule and von Willebrand factor immunoreactivity were suggestive of neo‐angiogenesis and neovasculogenesis taking place within nodules. Importantly, these vessels were HLA‐1(+) and, thus, clearly human in origin. Conclusions: This study indicates that CD34(+) cells obtained from dental pulp can be used for engineering bone, without the need for prior culture expanding procedures. Using autologous stem cells, this schedule could be used to provide the basis for bone regenerative surgery, with limited sacrifice of tissue, low morbidity at the collection site, and significant reduction in time needed for clinical recovery.

Matrix metalloproteinases belong to a growing family of proteases controlled by specific tissue inhibitors, involved in tissutal flogosis, wound healing, cancer invasion and metastasis. We developed an in vitro model to screen for potential toxic compounds in professional exposure. Human keratinocytes (HaCat) were used as target cells while matrix metalloproteinases (MMP) were selected as responders, developing and in vitro model of allergic dermatitis. The chemical agents: potassium dichromate and nickel sulphate as positive teste, because represent the main etiological agents of allergic dermatitis. Nickel contact at very low concentrations (10(-5), 10(-6) M) induced upregulation of MMP-2 and IL-8 mRNA production; chromium contact at very low concentrations killed all cells. Actually, our in vitro research is based on analysis of cytotoxic effects of xenobiotics on human lung fibroblasts; simultaneously we verified serum increasing in vivo of MMP-9, determinated in workers serum, exposed to anesthetic gas (fluorane). In only six exposed workers we observed MMP9 increasing over than normal range. Actually, we are continuing our research on a more representative sample.