Glial restricted precursor cell transplant with cyclic adenosine monophosphate improved some autonomic functions but resulted in a reduced graft size after spinal cord contusion injury in rats

Brain and Spinal Injury Center, Department of Neurological Surgery, 1001 Potrero Ave. Bld 1 Rm 101, University of California, San Francisco, CA 94110, USA.
Experimental Neurology (Impact Factor: 4.7). 10/2010; 227(1):159-71. DOI: 10.1016/j.expneurol.2010.10.011
Source: PubMed


Transplantation of glial restricted precursor (GRP) cells has been shown to reduce glial scarring after spinal cord injury (SCI) and, in combination with neuronal restricted precursor (NRP) cells or enhanced expression of neurotrophins, to improve recovery of function after SCI. We hypothesized that combining GRP transplants with rolipram and cAMP would improve functional recovery, similar to that seen after combining Schwann cell transplants with increasing cAMP. A short term study, (1) uninjured control, (2) SCI+vehicle, and (3) SCI+cAMP, showed that spinal cord [cAMP] was increased 14days after SCI. We used 51 male rats subjected to a thoracic SCI for a 12-week survival study: (1) SCI+vehicle, (2) SCI+GRP, (3) SCI+cAMP, (4) SCI+GRP+cAMP, and (5) uninjured endpoint age-matched control (AM). Rolipram was administered for 2weeks after SCI. At 9days after SCI, GRP transplantation and injection of dibutyryl-cAMP into the spinal cord were performed. GRP cells survived, differentiated, and formed extensive transplants that were well integrated with host tissue. Presence of GRP cells increased the amount of tissue in the lesion; however, cAMP reduced the graft size. White matter sparing at the lesion epicenter was not affected. Serotonergic input to the lumbosacral spinal cord was not affected by treatment, but the amount of serotonin immediately caudal to the lesion was reduced in the cAMP groups. Using telemetric monitoring of corpus spongiosum penis pressure we show that the cAMP groups regained the same number of micturitions per 24hours when compared to the AM group, however, the frequency of peak pressures was increased in these groups compared to the AM group. In contrast, the GRP groups had similar frequency of peak pressures compared to baseline and the AM group. Animals that received GRP cells regained the same number of erectile events per 24hours compared to baseline and the AM group. Since cAMP reduced the GRP transplant graft, and some modest positive effects were seen that could be attributable to both GRP or cAMP, future research is required to determine how cAMP affects survival, proliferation, and/or function of progenitor cells and how this is related to function. cAMP may not always be a desirable addition to a progenitor cell transplantation strategy after SCI.

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Available from: Esther Culp, May 13, 2014
    • "It is important to note that benefi ts of cAMP are often absent without co-administered neurotrophins, SCs or OECs (Lu et al., 2004; Pearse et al., 2004a). Furthermore, addition of cAMP may have harmful effects such as decrease graft survival (Nout et al., 2010). When applied thoughtfully, however, local db-cAMP and systemic upregulation by Rolipram promote axonal growth and synaptic plasticity in several cell transplantation strategies (Pearse et al., 2007; Bretzner et al., 2010). "
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    ABSTRACT: Stem cell transplantation offers an attractive potential therapy for neurological and neurodegenerative disorders such as spinal cord injury (SCI). Given the demand and expectations for the success of regenerative medicines, newly developed cellular therapeutics must be carefully designed and executed, informed by strong preclinical rationale available. This chapter will address the current state of preclinical scientific research for translation into clinical use of stem cell therapy. Focus will be given to current advances in cell transplantation strategies, with specific attention paid to critical assessment of mechanism and efficacy. Specific cell types will be discussed with respect to pathophysiological processes of SCI and their proposed targets. These therapeutics targets include: 1) trophic support and reducing cell loss, 2) remyelination and neuroprotection, 3) tissue modification, and 4) regeneration through neuroplasticity. Combinatorial strategies consisting of co-administering cell types, neurotrophins and tissue modification will also be addressed. Pressing considerations and challenges of translating preclinical findings into clinical therapy exist, and ought to be critically assessed with respect to the best current animal model data. Clinical trials of cell transplantation in human participants with spinal injuries are of significant importance, and will be critically appraised. Taken as a whole—while expectations must be measured—the current status of knowledge on stem cell transplantation for SCI has evolved substantially over the past decade. While translational knowledge gaps continue to exist with regard to cervical and chronic SCI, carefully conducted early phase clinical trials with cellular therapies are warranted, but must be complemented by a robust preclinical research strategy.
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    • "In light of these results, in-depth studies were then undertaken into changing each of the variables: pre-differentiation, the inducer, and the progenitor cell. Pre-differentiation has been proved crucial in consideration of the variable and modest outcomes of the grafted immature astrocytes (Bernstein and Goldberg, 1991; Hayashi et al., 2011; Joosten et al., 2004; Kliot et al., 1990; Olby and Blakemore, 1996; Pencalet et al., 2006; Wang et al., 1995) or precursors like GRPs (Hill et al., 2004; Mitsui et al., 2005; Nout et al., 2011). One possible explanation is that the exogenous astrocyte precursors might be destined for " scar astrocyte " -like phenotypes, because of a lack of beneficial signals or the overriding detrimental influences within the injured niche, such as inflammatory factors or BMPR signals (Alonso, 2005; Cao et al., 2002; Davies et al., 2006; Groves et al., 1993; Lue et al., 2010; McKeon et al., 1991). "
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    ABSTRACT: Spinal cord injury (SCI) often causes incurable neurological dysfunction because axonal regeneration in adult spinal cord is rare. Astrocytes are gradually recognized as being necessary for the regeneration after SCI as they promote axonal growth under both physiological and pathophysiological conditions. Heterogeneous populations of astrocytes have been explored for structural and functional restoration. The results range from the early variable and modest effects of immature astrocyte transplantation to the later significant, but controversial, outcomes of glial-restricted precursor (GRP)-derived astrocyte (GDA) transplantation. However, the traditional neuron-centric view and the concerns about the inhibitory roles of astrocytes after SCI, along with the sporadic studies and the lack of a comprehensive review, have led to some confusion over the usefulness of astrocytes in SCI. It is the purpose of the review to discuss the current status of astrocyte transplantation for SCI based on a dialectical view of the context-dependent manner of astrocyte behavior and the time-associated characteristics of glial scarring. Critical issues are then analyzed to reveal the potential direction of future research.
    Full-text · Article · Aug 2014 · Brain Research Bulletin
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    • "Our previous study 6 showed that transplantation of GRPs alone did not increase the spared white matter or functional recovery after contusion SCI. More recent studies also showed that transplantation of rat or human GRPs after contusion SCI improved the injured environment by reducing cyst and scar formation 44;45. But neither rat nor human GRP grafts resulted in significant axonal regeneration and locomotion functional recovery. "
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    ABSTRACT: The transplantation of neural stem/progenitor cells is a promising therapeutic strategy for spinal cord injury (SCI). In this study, we tested whether combination of neurotrophic factors and transplantation of glial-restricted precursor (GRPs)-derived astrocytes (GDAs) could decrease the injury and promote functional recovery after SCI. We developed a protocol to quickly produce a sufficiently large, homogenous population of young astrocytes from GRPs, the earliest arising progenitor cell population restricted to the generation of glia. GDAs expressed the axonal regeneration promoting substrates, laminin and fibronectin, but not the inhibitory chondroitin sulfate proteoglycans (CSPGs). Importantly, GDAs or its conditioned medium promoted the neurite outgrowth of dorsal root ganglion neurons in vitro. GDAs were infected with retroviruses expressing EGFP or multi-neurotrophin D15A and transplanted into the contused adult thoracic spinal cord at 8 days post-injury. Eight weeks after transplantation, the grafted GDAs survived and integrated into the injured spinal cord. Grafted GDAs expressed GFAP, suggesting they remained astrocyte lineage in the injured spinal cord. But it did not express CSPG. Robust axonal regeneration along the grafted GDAs was observed. Furthermore, transplantation of D15A-GDAs significantly increased the spared white matter and decreased the injury size compared to other control groups. More importantly, transplantation of D15A-GDAs significantly improved the locomotion function recovery shown by BBB locomotion scores and Tredscan footprint analyses. However, this combinatorial strategy did not enhance the aberrant synaptic connectivity of pain afferents, nor did it exacerbate posttraumatic neuropathic pain. These results demonstrate that transplantation of D15A-expressing GDAs promotes anatomical and locomotion recovery after SCI, suggesting it may be an effective therapeutic approach for SCI.
    Full-text · Article · Jan 2013 · International journal of biological sciences
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