Search

Traumatic peripheral nerve injuries constitute a huge concern to public health. Nerve damage leads to a decrease or even loss of mobility of the innervated area. Adult stem cell therapies have shown some encouraging results and have been identified as promising treatment candidates for nerve regeneration. A major obstacle to that approach is securing a sufficient number of cells at the injured site to produce measurable therapeutic effects. The present work tackles this issue and demonstrates enhanced nerve regeneration ability promoted by magnetic targeted cell therapy in an in vivo Wallerian degeneration model. To this end, adipose-derived mesenchymal stem cells (AdMSC) were loaded with citric acid coated superparamagnetic iron oxide nanoparticles (SPIONs), systemically transplanted and magnetically recruited to the injured sciatic nerve. AdMSC arrival to the injured nerve was significantly increased using magnetic targeting and their beneficial effects surpassed the regenerative properties of the stand-alone cell therapy. AdMSC-SPIONs group showed a partially conserved nerve structure with many intact myelinated axons. Also, a very remarkable restoration in myelin basic protein organization, indicative of remyelination, was observed. This resulted in an improvement in nerve conduction, demonstrating functional recovery. In summary, our results demonstrate that magnetically assisted delivery of AdMSC, using a non-invasive and non-traumatic method, is a highly promising strategy to promote cell recruitment and sciatic nerve regeneration after traumatic injury. Last but not least, our results validate magnetic targeting in vivo exceeding previous reports in less complex models through cell magnetic targeting in vitro and ex vivo., This research was funded by CONICET (Grant numbers PIP11220170101059CO and 897), ANPCYT (Grant number PICT 3952), UNLP (Grant numbers X11/680 and X11/784), and UBACYT (Grant number 20020130100024).

Iron (Fe) deficiency (FeD) and manganese (Mn) overexposure (MnOE) may result in several neurological alterations in the nervous system. Iron deficiency produces unique neurological deficits due to its elemental role in central nervous system (CNS) development and myelination, which might persist after normalization of Fe in the diet. Conversely, MnOE is associated with diverse neurocognitive deficits. Despite these well-known neurotoxic effects on the CNS, the influence of FeD and MnOE on the peripheral nervous system (PNS) remains poorly understood. The aim of the present investigation was to examine the effects of developmental FeD and MnOE or their combination on the sciatic nerve of young and adult rats. The parameters measured included divalent metal transporter 1 (DMT1), transferrin receptor (TfR), myelin basic protein (MBP) and peripheral myelin protein 22 (PMP22) expression, as well as Fe levels in the nerve. Our results showed that FeD produced a significant reduction in MBP and PMP22 content at P29, which persisted at P60 after Fe-sufficient diet replenishment regardless of Mn exposure levels. At P60 MnOE significantly increased sciatic nerve Fe content and DMT1 expression. However, the combination of FeD and MnOE produced no marked motor skill impairment. Evidence indicates that FeD appears to hinder developmental peripheral myelination, while MnOE may directly alter Fe homeostasis. Further studies are required to elucidate the interplay between these pathological conditions. Fil: Amos Kroohs, Robyn M.. University of North Carolina; Estados Unidos Fil: Usach, Vanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina Fil: Piñero, Gonzalo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina Fil: Vorhees, Charles V.. University of Cincinnati; Estados Unidos Fil: Martínez Vivot, Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina Fil: Soto, Paula Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina Fil: Williams, Michael T.. University of Cincinnati; Estados Unidos Fil: Setton, Clara Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentina

Previous work by our group demonstrated the key role of iron in Schwann cell (SC)maturation through an increase in cAMP, PKA activation and CREB phosphorylation. These studies opened the door to further research on a non-transferrin-bound iron uptake, which revealed the presence of DMT1 mRNA all along SC progeny, hinting at a constitutive role of DMT1 in ensuring the provision of iron in the PNS. In light of these previous results,the present work evaluates the participation of DMT1 in the remyelination process following a demyelinating lesion promoted by sciatic nerve crush ?a reversible model of Wallerian degeneration. DMT1 was observed to colocalize with SC marker S100β at all survival times analyzed. In turn, the assessment of DMT1 mRNA expression exhibited an increase 7 days post-injury, while DMT1 protein levels showed an increase 14 days after crush at the lesion site and distal stump; finally, an increase in iron levels became evidentas from 14 days post-injury, in parallel with DMT1 values. To sum up, the present work unveils the role of DMT1 in mediating the neuroregenerative action of iron. Fil: Martínez Vivot, Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Fisicoquímica Biológicas; Argentina Fil: Copello, Guillermo Javier. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica. Cátedra de Química Analítica Instrumental; Argentina Fil: Leal, Maria Celeste. Fundación Instituto Leloir; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; Argentina Fil: Piñero, Gonzalo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Fisicoquímica Biológicas; Argentina Fil: Usach, Vanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Fisicoquímica Biológicas; Argentina Fil: Rozenszajn, Mijael. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Fisicoquímica Biológicas; Argentina Fil: Morelli, Laura. Fundación Instituto Leloir; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; Argentina Fil: Setton, Clara Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Fisicoquímica Biológicas; Argentina

BACKGROUND: Reinnervation timing after nerve injury is critical for favorable axonal regeneration, remyelination and clinical improvement. Considering bone marrow mononuclear cells (BMMC) are easily obtained and readily available for transplant, this work analyzed the effect of BMMC systemic administration on nerve repair and pain behavior.METHODS: Adult rats with sciatic nerve crush were immediately and systemically injected BMMC through the caudal artery. Nontreated, sham and naïve rats were also included. Histological, immunohistochemical, biochemical, functional and behavioral analyses were performed in nerves harvested from each group at different survival times.RESULTS: Axons in BMMC-treated rats exhibited a more conserved morphological appearance than those in nontreated rats, as observed at different survival times both in semi-thin sections and ultrastructural analysis. BMMC-treated rats also showed a reduction in major myelin protein immunoreactive clusters 7 and 14 days post injury (DPI), as compared to nontreated rats. Electrophysiological analysis showed BMMC treatment to slightly improve the amplitude of compound muscle action potential (CMAP) starting at 14 DPI. Finally, mechanical withdrawal threshold revealed a full preventive action against transient mechanical hypersensitivity in BMMC-treated rats.CONCLUSIONS: These data demonstrate the efficiency of BMMC, systemically and noninvasively transplanted, in correcting morphological, functional and behavioral alterations resulting from peripheral nerve injury. Fil: Usach, Vanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina Fil: Malet, Mariana. Universidad Austral. Facultad de Ciencias Biomédicas. Instituto de Investigaciones en Medicina Traslacional. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Medicina Traslacional; Argentina Fil: Lopez, Lidia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia ; Argentina Fil: Lavalle, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina Fil: Piñero, Gonzalo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina Fil: Saccoliti, María. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos ; Argentina Fil: Cueto, Alicia. Gobierno de la Ciudad de Buenos Aires. Hospital Español. Servicio de Neurología; Argentina Fil: Brumovsky, Pablo Rodolfo. Universidad Austral. Facultad de Ciencias Biomédicas. Instituto de Investigaciones en Medicina Traslacional. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Medicina Traslacional; Argentina Fil: Brusco, Herminia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia ; Argentina Fil: Setton, Clara Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina

In the present work, we analyzed whether endogenous and/or transplanted bone marrow mononuclear cells (BMMC) migrate spontaneously to the crushed sciatic nerve and whether they transdifferentiate into Schwann cells (SC) in order to help repair the damaged tissue. We also studied both the immunohistochemical evolution of myelin proteins MBP and P0 and the myelin composition of both the proximal and distal stumps of the crushed sciatic nerve to determine the demyelination–remyelination period. Immunohistochemical analysis of crushed animals showed that the degeneration process consists of loss of nerve fiber integrity accompanied by degradation of myelin basic proteins MBP and P0, which is anticipated by protein cluster formation. The remyelination process appears as a recovery in nerve fiber structure as well as in MBP and P0 immunoreactivity; results obtained studying isolated myelin from the crushed sciatic nerve show a strong correlation between them. As opposed to demyelination, axonal damage is observed for a short period of time and takes place mostly in the crush area and the segments adjacent to the lesion. Evidence of spontaneous migration of endogenous or intravascularly transplanted BMMC (CD34+ and vimentin+) is found during the demyelination period exclusively to the injured sciatic nerve. Once migration takes place, transdifferentiation to SC is observed. Such migration and transdifferentiation processes might be inferred to constitute a spontaneous repair mechanism after nerve injury. © 2011 Wiley-Liss, Inc.

Iron, either in its chelated form or as holotransferrin (hTf), prevents the dedifferentiation of Schwann cells (SC), cells responsible for the myelination of the peripheral nervous system (PNS). This dedifferentiation is promoted by serum deprivation through cAMP release, PKA activation, and CREB phosphorylation. Since iron elicits its effect in a transferrin (Tf)-free environment, in this work we postulate that non-transferrin-bound iron (NTBI) uptake must be involved. Divalent metal transporter 1(DMT1) has been widely described in literature as a key player in iron metabolism, but never before in the PNS context. The presence of DMT1 was demonstrated in nerve homogenate, isolated adult-rat myelin, and cultured SC by Western Blot (WB) analysis and confirmed through its colocalization with S-100β (SC marker) by immunocytochemical and immunohistochemical analyses. Furthermore, the existence of its mRNA was verified in sciatic nerve homogenate by RT-PCR and throughout SC maturational stages. Finally, we describe DMT1's subcellular location in the plasma membrane by confocal microscopy of SC and WB of different subcellular fractions. These data allow us to suggest the participation of DMT1 as part of a Tf independent iron uptake mechanism in SC and lead us to postulate a crucial role for iron in SC maturation and, as a consequence, in PNS myelination.