The ability of intraspinal bone marrow stromal cell (BMSC) transplants to elicit repair is thought to result from paracrine effects by secreted trophic factors including brain-derived neurotrophic factor (BDNF). Here we used gene therapy to increase or silence BDNF production in BMSCs to investigate the role of BDNF in BMSC-mediated neuroprotection. In a spinal cord organotypic culture, BMSC-conditioned medium significantly enhanced spinal motoneuron survival by 64% compared with culture medium only. Only conditioned medium of BDNF-hypersecreting BMSCs sustained this neuroprotective effect. In a rat model of spinal cord contusion, a BDNF-dependent neuroprotective effect was confirmed; only with a subacute transplant of BDNFhypersecreting BMSCs were significantly more spared motoneurons found at 4 weeks postinjury compared with vehicle controls. Spared nervous tissue volume was improved by 68% with both control BMSCs and BDNF-hypersecreting BMSCs. In addition, blood vessel density in the contusion with BDNF-hypersecreting BMSCs was 35% higher compared with BMSC controls and sixfold higher compared with vehicle controls. BDNF-silenced BMSCs did not survive the first week of transplantation, and no neuroprotective effect was found at 4 weeks after transplantation. Together, our data broaden our understanding of the role of BDNF in BMSC-mediated neuroprotection and successfully exploit BDNF dependency to enhance anatomical spinal cord repair.

Prostate cancer (PCa) is believed to metastasize through the blood/lymphatics systems; however, PCa may utilize the extensive innervation of the prostate for glandular egress. The interaction of PCa and its nerve fibers is observed in 80% of PCa and is termed perineural invasion (PNI). PCa cells have been observed traveling through the endoneurium of nerves, although the underlying mechanisms have not been elucidated. Voltage sensitive sodium channels (VSSC) are multimeric transmembrane protein complexes comprised of a pore-forming α subunit and one or two auxiliary beta (β) subunits with inherent cell adhesion molecule (CAM) functions. The beta-2 isoform (gene SCN2B) interacts with several neural CAMs, while interacting putatively with other prominent neural CAMs. Furthermore, beta-2 exhibits elevated mRNA and protein levels in highly metastatic and castrate-resistant PCa. When overexpressed in weakly aggressive LNCaP cells (2BECFP), beta-2 alters LNCaP cell morphology and enhances LNCaP cell metastasis associated behavior in vitro. We hypothesize that PCa cells use beta-2 as a CAM during PNI and subsequent PCa metastasis. The objective of this study was to determine the effect of beta-2 expression on PCa cell neurotropic metastasis associated behavior. We overexpressed beta-2 as a fusion protein with enhanced cyan fluorescence protein (ECFP) in weakly aggressive LNCaP cells and observed neurotropic effects utilizing our novel ex vivo organotypic spinal cord co-culture model, and performed functional assays with neural matrices and atomic force microscopy. With increased beta-2 expression, PCa cells display a trend of enhanced association with nerve axons. On laminin, a neural CAM, overexpression of beta-2 enhances PCa cell migration, invasion, and growth. 2BECFP cells exhibit marked binding affinity to laminin relative to LNECFP controls, and recombinant beta-2 ectodomain elicits more binding events to laminin than BSA control. Functional overexpression of VSSC beta subunits in PCa may mediate PCa metastatic behavior through association with neural matrices.

Castillo DG, Zahner MR, Schramm LP. Identification of the spinal pathways involved in the recovery of baroreflex control after spinal lesion in the rat using pseudorabies virus. Am J Physiol Regul Integr Comp Physiol 303: R590 -R598, 2012. First published July 18, 2012 doi:10.1152/ajpregu.00008.2012.-Neurons in the rostroventrolateral medulla (RVLM) mediate baroreflex regulation (BR) of spinal sympathetic preganglionic neurons. Previously, our laboratory has shown that recovery of BR occurs in the rat after spinal hemisection. (Zahner MR, Kulikowicz E, and Schramm LP. Am J Physiol Regul Integr Comp Physiol 301: R1584 -R1590, 2011. The goal of these experiments was to determine whether the observed recovery of BR is mediated by the reorganization of ipsilateral pathways or by compensation by spared contralateral pathways. To determine this, we infected the left kidney in rats with the retrograde transynaptic tracer, pseudorabies virus (PRV), either 1 or 8 wk after left spinal hemisection at either T3 or T8, or after a sham lesion. In sham-lesioned rats, PRV infection of RVLM neurons was bilateral. In all rats with a left hemisection, regardless of the location of the lesion (T3 or T8) or postlesion recovery time (1 or 8 wk), PRV infection of left RVLM neurons was significantly reduced compared with sham-lesioned rats (P Ͻ 0.05). In a separate group of rats, we performed BR tests by measuring responses of left renal sympathetic nerve activity to pharmacologically induced decreases and increases in arterial pressure. In rats with T8 left hemisection and 8-wk recovery, BR was robust, and acute right upper thoracic hemisection abolished all BR of left renal sympathetic nerve activity. Collectively, these data suggest that the recovery of BR is not mediated by reorganization of ipsilateral bulbospinal connections, but instead by improved efficacy of existing contralateral pathways. renal sympathetic nerve activity; cardiovascular regulation; spinal cord injury; baroreflex BAROREFLEX REGULATION (BR) of sympathetic and parasympathetic activity is an important mechanism for the moment-tomoment regulation of arterial pressure (AP) (8, 13). Loss of BR after spinal cord injury (SCI) can seriously impair sympathetic cardiovascular regulation. After SCI, the decreased ability to regulate sympathetic activity leaves patients at risk to varying degrees of orthostatic intolerance or autonomic dysreflexia with hypertensive crises. Orthostatic intolerance results from insufficient BR-mediated sympathetic outflow to maintain an upright posture without syncope (1,6,14,15,30). Autonomic dysreflexia occurs due to diminished suppression of spinal sources of sympathetic activity caudal to the lesion (10,14,16,22,31,32). Both conditions can be attributed to limited regulation of the activity of spinal sympathetic preganglionic neurons caudal to the lesion.Neurons in the rostral ventrolateral medulla (RVLM) are responsible for the excitability of sympathetic BR via projections to sympathetic preganglionic neurons located in the interme...