Growth and repair of skeletal muscle are normally mediated by the satellite cells that surround muscle fibers. In regenerating muscle, however, the number of myogenic precursors exceeds that of resident satellite cells, implying migration or recruitment of undifferentiated progenitors from other sources. Transplantation of genetically marked bone marrow into immunodeficient mice revealed that marrow-derived cells migrate into areas of induced muscle degeneration, undergo myogenic differentiation, and participate in the regeneration of the damaged fibers. Genetically modified, marrow-derived myogenic progenitors could potentially be used to target therapeutic genes to muscle tissue, providing an alternative strategy for treatment of muscular dystrophies.

Objective-To test the potential of mesoangioblasts (Mabs) in reducing postischemic injury in comparison with bone marrow progenitor cells (BMPCs), fibroblasts (Fbs), and embryonic stem cell-derived endothelial cells (ECs), and to identify putative cellular protective mechanisms. Methods and Results-Cells were injected percutaneously in the left ventricular (LV) chamber of C57BL/6 mice, 3 to 6 hours after coronary ligation, and detected in the hearts 2 days and 6 weeks later. Echocardiographic examinations were performed at 6 weeks. LV dilation was reduced and LV shortening fraction was improved with Mabs and BMPCs but not with ECs and Fbs. Donor cell colonization of the host myocardium was modest and predominantly in the smooth muscle layer of vessels. Capillary density was higher in the peripheral infarct area and apoptotic cardiomyocytes were fewer with Mabs and BMPCs. Mabs and BMPCs, but not Fbs or ECs, promoted survival of cultured cardiocytes under low-oxygen in culture. This activity was present in Mab-conditioned medium and could be replaced by a combination of basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF)-1, and hepatocyte growth factor (HGF), all of which are produced by these cells. Conditioned medium from Mabs, but not from Fbs, stimulated proliferation of smooth muscle cells in vitro. Conclusions-Mabs

Sinus lift augmentation is a procedure required for the placement of a dental implant, whose success can be limited by the quantity or quality of available bone. To this purpose, the first aim of the current study was to evaluate the ability of autologous periosteum-derived micrografts and Poly(lactic-co-glycolic acid) (PLGA) supplemented with hydroxyl apatite (HA) to induce bone augmentation in the sinus lift procedure. Secondly, we compared the micrograft's behavior with respect to biomaterial alone, including Bio-Oss® and PLGA/HA, commercially named Alos. Sinus lift procedure was performed on 24 patients who required dental implants and who, according to the study design and procedure performed, were divided into three groups: group A (Alos + periosteum-derived micrografts); group B (Alos alone); and group C (Bio-Oss® alone). Briefly, in group A, a small piece of periosteum was collected from each patient and mechanically disaggregated by Rigenera® protocol using the Rigeneracons medical device. This protocol allowed for the obtainment of autologous micrografts, which in turn were used to soak the Alos scaffold. At 6 months after the sinus lift procedure and before the installation of dental implants, histological and radiographic evaluations in all three groups were performed. In group A, where sinus lift augmentation was performed using periosteum-derived micrografts and Alos, the bone regeneration was much faster than in the control groups where it was performed with Alos or Bio-Oss® alone (groups B and C, respectively). In addition, the radiographic evaluation in the patients of group A showed a radio-opacity after 4 months, while after 6 months, the prosthetic rehabilitation was improved and was maintained after 2 years post-surgery. In summary, we report on the efficacy of periosteum-derived micrografts and Alos to augment sinus lift in patients requiring dental implants. This efficacy is supported by an increased percentage of vital mineralized tisssue in the group treated with both periosteum-derived micrografts and Alos, with respect to the control group of Alos or Bio-Oss® alone, as confirmed by histological analysis and radiographic evaluations at 6 months from treatment.

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