Publications (53) View all
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Article: Repairing nerve gaps by vein conduits filled with lipoaspirate-derived entire adipose tissue hinders nerve regeneration.
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ABSTRACT: In spite of great recent advancements, the definition of the optimal strategy for bridging a nerve defect, especially across long gaps, still remains an open issue since the amount of autologous nerve graft material is limited while the outcome after alternative tubulization techniques is often unsatisfactory. The aim of this study was to investigate a new tubulization technique based on the employment of vein conduits filled with whole subcutaneous adipose tissue obtained by lipoaspiration. In adult rats, a 1cm-long defect of the left median nerve was repaired by adipose tissue-vein-combined conduits and compared with fresh skeletal muscle tissue-vein-combined conduits and autologous nerve grafts made by the excised nerve segment rotated by 180°. Throughout the postoperative period, functional recovery was assessed using the grasping test. Regenerated nerve samples were withdrawn at postoperative month-6 and processed for light and electron microscopy and stereology of regenerated nerve fibers. Results showed that functional recovery was significantly slower in the adipose tissue-enriched group in comparison to both control groups. Light and electron microscopy showed that a large amount of adipose tissue was still present inside the vein conduits at postoperative month-6. Stereology showed that all quantitative morphological predictors analyzed performed significantly worse in the adipose tissue-enriched group in comparison to the two control groups. On the basis of this experimental study in the rat, the use of whole adipose tissue for tissue engineering of peripheral nerves should be discouraged. Pre-treatment of adipose tissue aimed at isolating stromal vascular fraction and/or adipose derived stem/precursor cells should be considered a fundamental requisite for nerve repair.Annals of anatomy = Anatomischer Anzeiger: official organ of the Anatomische Gesellschaft 12/2012; · 0.88 Impact Factor -
Article: Morphological, molecular and functional differences of adult bone marrow- and adipose-derived stem cells isolated from rats of different ages.
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ABSTRACT: Adult mesenchymal stem cells have self-renewal and multiple differentiation potentials, and play important roles in regenerative medicine. However, their use may be limited by senescence or age of the donor, leading to changes in stem cell functionality. We investigated morphological, molecular and functional differences between bone marrow-derived (MSC) and adipose-derived (ASC) stem cells isolated from neonatal, young and old rats compared to Schwann cells from the same animals. Immunocytochemistry, RT-PCR, proliferation assays, western blotting and transmission electron microscopy were used to investigate expression of senescence markers. Undifferentiated and differentiated ASC and MSC from animals of different ages expressed Notch-2 at similar levels; protein-38 and protein-53 were present in all groups of cells with a trend towards increased levels in cells from older animals compared to those from neonatal and young rats. Following co-culture with adult neuronal cells, dMSC and dASC from animals of all ages elicited robust neurite outgrowth. Mitotracker(®) staining was consistent with ultrastructural changes seen in the mitochondria of cells from old rats, indicative of senescence. In conclusion, this study showed that although the cells from aged animals expressed markers of senescence, aged MSC and ASC differentiated into SC-like cells still retain potential to support axon regeneration.Experimental Cell Research 05/2012; 318(16):2034-48. · 3.58 Impact Factor -
Article: Self-Renewal and Multipotency Coexist in a Long-Term Cultured Adult Rat Dental Pulp Stem Cell Line: An Exception to the Rule?
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ABSTRACT: The stemness state is characterized by self-renewal and differentiation properties. However, stem cells are not able to preserve these characteristics in long-term culture because of the intrinsic fragility of their phenotype easily undergoing senescence or neoplastic transformation. Furthermore, although isolated from the same original tissue using similar protocols, adult stem cells can display dissimilar phenotypes and important cell clone/species contamination. Finally, the lack of a clear standardization contributes to complicate the comprehension about the stemness condition. In this context, cell lines displaying a particularly stable phenotype must be identified to define one or multiple benchmarks against which other stem cell lines could be reliably assessed. The present paper demonstrates that it is possible to isolate from the rat dental pulp a stem cell line (MUR-1) that does not display neoplastic transformation in long-term culture. MUR-1 cells stably express a broad range of stemness markers and are able to differentiate into adipogenic, osteogenic, chondrogenic, neurogenic, and cardiomyogenic lineages independently of the culture passages. Moreover, serial in vitro passages have not changed their immunophenotype, proliferation capacity, or differentiation potential. The uniqueness of these characteristics candidates MUR-1 as a model to reliably improve the understanding of the mechanisms governing the stem cell fate in the same as well as in other stem cell populations.Stem cells and development 05/2012; · 4.15 Impact Factor -
Article: Expression of antioxidant molecules after peripheral nerve injury and regeneration.
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ABSTRACT: Oxidative stress is considered to be one of the main causes of neural damage after injury. However, little is known about the changes in mRNA expression of antioxidant molecules that occur after injury and regeneration of the peripheral nerve. In the present study, the rat median nerve was transected, and transcriptional changes were studied at day 6 and day 12 after injury in both the proximal and the distal stumps, in the absence or presence of microsurgical repair. The expression profiles of the following genes were investigated: three metallothionein isoforms (MT-1, MT-2, and MT-3), the main antioxidant enzymes (catalase, superoxide dismutase, and glutathione-S-transferase), and the marker of cellular damage poly(ADP-ribose) polymerase-1 (PARP-1). The results showed that, in the proximal nerve stump, MT-3 mRNA expression was significantly and markedly up-regulated in the absence of surgical repair, whereas MT-1 and MT-2 showed significant down-regulation. In the distal nerve portion, mRNA expression of all MT isoforms decreased significantly in the absence of microsurgical reconstruction, whereas, after repair, MT-3 mRNA expression alone was up-regulated. Expression of all the antioxidant enzymes decreased significantly after repair in the proximal nerve portion, but a significant general increase in their mRNA expression was revealed in the distal nerve stump. PARP-1 expression was significantly up-regulated in the proximal nerve portion without repair but dramatically reduced after reconstruction. In contrast, PARP-1 expression increased markedly in the distal stump after surgical repair. Taken together, these findings indicate that antioxidant molecules are differentially modulated and might, therefore, play an important role in peripheral nerve injury and regeneration.Journal of Neuroscience Research 04/2012; 90(4):842-8. · 2.74 Impact Factor -
Article: Can regenerated nerve fibers return to normal size? A long-term post-traumatic study of the rat median nerve crush injury model.
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ABSTRACT: Whether post-traumatic regeneration can eventually result in rat peripheral nerve fibers regaining their pretrauma size is still an open question. While it has been shown that, after a sufficient duration in post-traumatic time, the number of regenerated rat peripheral nerve fibers can return to pretrauma numbers and the animal can regain normal prelesion function, no information regarding long-term changes in the size parameters of the regenerated nerve fibers is available. To fill this gap, we have investigated the post-traumatic changes in myelinated axon and nerve fiber diameter, myelin thickness, and g-ratio (the ratio of the inner axonal diameter to the fiber diameter) at three different time points following nerve injury: week-6, week-8, and week-24. A standardized nerve crush injury of the rat median nerve obtained using a nonserrated clamp was used for this study. The results showed that, consistent with previous studies, fiber number returned to normal values at week-24, but both axon and fiber diameter and myelin thickness were still significantly lower at week-24 than prelesion, and the g-ratio, which remained unchanged during the regeneration process, was significantly reduced at week-24 in comparison to the prelesion value. On the basis of these results, the hypothesis that regenerated rat peripheral nerve fibers are able to return spontaneously to their normal pretrauma state, provided there is a sufficiently long recovery time postaxonotmesis, is not supported.Microsurgery 03/2012; 32(5):383-7. · 1.61 Impact Factor
