Research Topics: Pleiotrophin
A current focus of the Sortwell Laboratory is understanding how the growth factor pleiotrophin (PTN) participates in the development and maintenance of the nigrostriatal system. Neurotrophic factors have great potential as therapeutics in PD by providing long-term efficacy without the disabling side effects associated with current pharmacological treatments. She is currently studying the potential of PTN to provide neurorestoration in rat models of PD, testing the hypothesis that viral vector-mediated overexpression of PTN in the adult rat nigrostriatal system can facilitate long-term functional recovery. Additional studies will examine whether PTN overexpression can improve dopamine graft survival and innervation of the denervated host striatum. This project has received funding from the Michael J. Fox Foundation and the National Institute of Neurological Disorders and Stroke (NINDS).
Figure 1. Characterization of PTN Expression after Intrastriatal rAAV2/1-PTN/GFP Injection. A-H. Triple labeled immunofluorescence confocal images of striatal (A-D) and nigral (E-H) neurons in rats injected with rAAV2/1-PTN/GFP (2 μl x 1 sites). Merged GFAP, NeuN, and PTN images (D, H) indicate that rAAV2/1-PTN/GFP transduction is localized to neurons. I. Western blot PTN immunodetection in naïve striatal samples from rats across developmental ages with highest expression between ages E20 and P1. J. Western blot immunodetection from striatal samples of naïve P1 and P2 rats or 6-OHDA lesioned adult rats transduced with rAAV2/1-PTN/GFP (2 μl x 2 sites) or contralateral uninjected striatum. K. Western blot quantification of striatal PTN levels in naïve P1 rats or 6-OHDA lesioned adult rats transduced with either rAAV2/1-PTN/GFP or rAAV2/1-GFP (2 μl x 2 sites) and the corresponding contralateral uninjected striatum. PTN expression in the adult rAAV2/1-PTN/GFP striatum approximately tripled that of rAAV2/1-GFP injected animals and naïve controls, and was not significantly different from P1 levels (*, p>0.05). Values expressed as the mean percent of control ± SEM for each group. L. An example of GFP immunoreactivity in striatum of rAAV2/1-PTN/GFP transduced adult rat 20 weeks after vector injection (2 μl x 2 sites). The average striatal volume was 1.32 x1010 ± 9.65 x108 µm3 and average GFPir volume within the striatum was 7.58 x109 ± 2.31 x109 µm3, approximately 57% of total striatal volume. Values are expressed as mean ± SEM.
Figure 2. Long Term PTN Overexpression FacilitatesFunctional Restoration of 6-OHDA Induced Deficits in Contralateral Forelimb Use. A. Forelimbakinesia in the cylinder task. Rats received unilateral intrastriatalinjection of rAAV2/1 GFP, PBS or rAAV2/1-PTN/GFP (3 μlx 1 site) 4 weeks prior to intrastriatal 6-OHDA. 6-OHDAproduced significant deficits in contralateral forelimb use in control rats(rAAV2/1 GFP or PBS, ☐) at all post 6-OHDA timepoints evaluated and in rats receiving PTN vector at 5 and 9 weeks after 6-OHDA(l, *, p < 0.05). However, rats receivingPTN vector exhibited recovery of contralateral forepaw use to near pre 6-OHDAlevels at 13 and 17 weeks post lesion (#, p = n.s.), B. Intrastriatal rAAV2/1-PTN/GFP injection yielded significant neuroprotection for SNpc THirnigral neurons eighteen weeks after 6-OHDA (*, p = 0.009). C. GFP and D. PTN immunoreactivity twenty-twoweeks following striatal injection ofrAAV2/1-PTN/GFP. Inset in D. At higher magnification PTN expressionappears to colocalize with cellular structures in the striatum. E-F. Representative photomicrographs of THir SNpc neurons in lesioned SNpc ofrAAV2/1-GFP (F) and rAAV2/1-PTN/GFP (E) injected rats.rAAV2/1-PTN/GFP transduction spared more THir neurons in the lesioned SNpc (E) compared to rAAV2/1-GFP transduction (F). Valuesexpressed as the mean percent of control ± SEM for each group.
Deep Brain Stimulation
An additional focus of Dr. Sortwell's laboratory is to understand whether deep brain stimulation (DBS) of the subthalamic nucleus (STN) can slow down the progression of Parkinson's disease. DBS of the STN has become the most often practiced neurosurgery for alleviation of the PD symptoms. Due to the therapeutic efficacy of this approach, its use clinically has outpaced our scientific understanding of its mechanism of action. Dr. Sortwell and her collaborators are currently examining the magnitude and mechanism of neuroprotection conferred by STN DBS in parkinsonian rats. The results of these studies will inform the optimal therapeutic timing for intervention with STN DBS in PD patients. This project has received funding from the Davis Phinney Foundation, the American Parkinson’s Disease Association and is part of the Udall Center of Excellence at Michigan State University (NINDS). (Click here to visit Dr. Sortwell's Udall Project 2 page.)
In collaboration with Dr. Jeff MacKeigan (Van Andel Research Institute) Dr. Sortwell studies whether the drug fasudil can be sucessfully repurposed for Parkinson’s disease (PD). Fasudil is a kinase inhibitor that is approved for the treatment of cerebral vasospasm in humans. The target of fasudil is highly active under conditions of inflammation and injury, and target inhibition by fasudil enhances axonal growth, regeneration, and promotes neurological recovery following spinal cord injury, making fasudil a promising therapeutic drug for neurological diseases. In addition, fasudil has been shown to be neuroprotective against oxidative stress and suppresses inflammatory responses, both of which have been implicated in the etiology of PD. The objective of this project is to determine whether fasudil has the therapeutic potential to protect and restore degenerating nigrostriatal neurons. This project has received funding from the Michael J. Fox Foundation.
Interactions of Alpha-Synuclein with the Aged Brain
Accurate preclinical models of Parkinson’s disease (PD) are needed in order to test novel therapies as well as to further our understanding of the disease itself. The molecule alpha-synuclein has been linked to many forms of PD and overexpression of alpha-synuclein has been used to recapitulate key pathophysiological features of PD. However, since aging is the primary risk factor for the development of PD it is important to evaluate how the aged brain responds to alpha-synuclein overexpression. This project examines whether overexpression of alpha-synuclein in the aged rat brain will lead to a greater magnitude of degeneration than what occurs in the younger brain. The combined model of alpha-synuclein overexpression in the aged rat may more accurately model the parkinsonian brain. Characterization of this combined model is therefore of value to the research community. If alpha-synuclein overexpression leads to amplified toxicity in the aging brain, then delineating the cause(s) of this increased toxicity may provide insight into the disease process itself. Follow up studies could start with the investigation of whether differences exist between alpha-synuclein infected young and aged rats in levels of neuroinflammation and/or oxidative stress. This project has received funding from the Michael J. Fox Foundation.
Figure 3. Overexpression of α-synuclein in the Rat Nigrostriatal System Via rAAV2/5 Viral Vector. A-H. Example of expression following unilateral (left side) intranigral injection of rAAV2/5 α-syn mixed with green fluorescent protein (GFP) vector. GFP immunolabeling indicates robust transduction of the entire nigrostriatal system (identified with labeling for tyrosine hydroxylase (TH). D, H. In adjacent sections α-syn expression follows an identical staining pattern. Insets in G illustrate examples of α-syn aggregates within a THir nigral neuron (α-syn antisera utilized in this example) and multiple transduced THir SN neurons. Note that this early time point after vector injection illustrates α-syn expression prior to degeneration. I. At 1 month following injection of high titer rAAV2/5 α-syn there is a marked decrease in THir neurons (left side) in the SN (arrow).
Sortwell Laboratory Personnel
|Pictured left to right: Caryl E. Sortwell and Christopher J. Kemp|
STAFF:Christopher J. Kemp, M.S
Chris joined the Sortwell Lab in 2010 at Michigan State University. He is originally from Birmingham, UK where he received a degree in Applied Biological Sciences from the University of West England in 1996. He went on to obtain a masters degree in Epidemiology and Biostatistics from the University of Cincinnati in 2007. Chris has previously held research positions at Cincinnati Children’s Hospital Medical Center, the University of Cincinnati and the University of Otago in New Zealand. His areas of technical expertise include molecular biology, immunohistochemistry, and behavioral evaluations. In the Sortwell Lab Chris focuses on the rodent deep brain stimulation project. In his spare time he likes to spend time with his kids, traveling, playing the ukulele, taking photographs and writing books.
|Sortwell Lab left to right, Megan Duffy, Christ Kemp, Luke Fischer, Nicole Polinski and Caryl Sortwell.|
Megan Duffy, B.S.
Megan joined the Sortwell Lab in 2014 and is being co-mentored by Dr. Timothy Collier. She received a B.S. in Psychology and a certificate in Neuroscience with minors in Biology and History from Indiana University Bloomington in 2013. As an undergraduate, Megan worked as a research assistant in the laboratory of Dr. George Rebec, utilizing fast-scan cyclic voltammetry to analyze dopamine release dynamics in mouse models of Huntington's Disease. Her current research focuses on characterizing the neuroinflammatory response in different alpha-synuclein models of Parkinson's disease (rAAV alpha-synuclein overexpression versus injection of pre-formed alpha-synuclein fibrils) to determine which animal model most accurately represents neuroinflammation in the human condition. In her spare time, Megan enjoys leading an active lifestyle, traveling to Europe to visit family and friends, and cooking.
D. Luke Fischer, B.A., B.S.
Luke joined the Sortwell Lab in 2010. Luke is an East Grand Rapids, MI native and received both his B.S. in Biochemistry and Molecular Biology and B.A. in Philosophy from Michigan State University in East Lansing, MI in 2010. As an undergraduate, Luke worked in the Radiology Department with Dr. Andrea Bozoki and Dr. Kevin Berger. His current research focuses on characterizing the effects of deep brain stimulation as a therapy for Parkinson's disease. Apart from his studies, Luke has collected artwork along his travels, especially contemporary African pieces, and also has a penchant for gastronomy and enology.
Nicole Polinski, B.A.
Nicole joined the Sortwell lab in 2013. She is a Michigan native, born and raised in the metro-Detroit area. Nicole received her B.A. in Biology from Kalamazoo College in Kalamazoo, MI in 2012. As an undergraduate, Nicole worked at The Ohio State University in the laboratory of Dr. Phillip Popovich studying spinal cord injury and inflammation. In addition, Nicole worked in the laboratory of Dr. Robert Batsell studying taste aversion learning at Kalamazoo College. Her current research focuses on characterizing the efficacy of viral vectors in the aged as compared to young adult rodent brain. In her spare time Nicole volunteers with the elderly, travels internationally, and reads classic literature (her favorite being Russian literature).