Specific overground walking kinematic measures are related to degree of spinal injury in the rat

1. d c b a Specific overground walking kinematic measures are related to degree of spinal injury in the rat Anil K. Thota, Ranu Jung, PhDAdaptive Neural Systems Laboratory, Department of Biomedical Engineering, Florida International University http://ans.fiu.edu #152 Introduction Results • After incomplete spinal cord thoracic injury (iSCI) rodents retain locomotorcapability • Hindlimb gross motor function mainly depends on axonal tracts in white matter that connect to thesupraspinalcentres • Hindlimb fine motor function mainly depends on local reflex circuitry in grey matter • Behavioral observational measures may not be sufficiently sensitive to assess both fine and gross motor functions • Quantitative measures such as 2D or 3D kinematic analyses are necessary to assess both fine and gross motor functions Red: White Matter; Yellow: Grey Matter; Orange: Central Canal Pink: Lesion Epicenter(A10) Caudal Rostral Area (mm2) Caudal(A19) Rostral(A0) 12 weeks post iSCI (hindlimbfoot rotation & ankle extension) Sham injured rat (No hindlmbfoot rotation) Hypothesis: Recovery of locomotor function after iSCIis related to white and grey matter sparing in the spinal cord T8 T9 T10 T11 T12 Volumes from 5 iSCI rats: White Matter = 19.6±3.9mm3 Grey Matter = 4.5±1.8mm3 • Volumes Spared: • White Matter = 47.6±6.5% • Grey Matter = 10.9±4.0% Length (mm) Methods • Post iSCIBBB ↓ • r=0.93; p<0.05 • Subjects • Sham injury (n=3): laminectomy at T10 • Incomplete spinal cord injury (iSCI, n=5): 10gm NYU Impactordropped from 12.5mm at T10 • Histology • Harvesting: T8-T11 spinal sections at 9th(n=2) and at 13th (n=3) weeks post injury • Embedding: 20% sucrose/PBS/gum tragacanth solution; stored at -80ºC • Cryosections: 20µm sections spaced at 500 µm • Staining: Eriochrome Cyanine RC for myelin (white matter) • Spinal Lesion Measures • Tracing: White Matter (WM), Grey Matter (GM) and Central Canal (CC) and Lesion (L) (Ludl computer controlled microscope stage and Neurolucida®stereoroligical imaging software) • 3D reconstruction:Cavalieriestimation principle to calculate volumes of WM. GM, CC and L using NeuroExplorer® Aij = cross sectional area of ithsection of jth rat lR and lLdistances between the A1 to A10 and A11 to A18respectively • Estimation of tissue spared: Post iSCI stance width ↑ r=-0.924; p<0.05 • Behavioral Measure: • Basso Beattie Bresnahan (BBB): Open field locomotor score (scale:0-21, 0-no hindlimb control, 21 normal) • Overground Walking Kinematic Measures: Injury epicenter 3.5 mm rostral to the injury epicenter 3.5 mm caudal to the injury epicenter 3D reconstruction of 9 mm spinal cord section between T8 and T12 for an intact rat and for an iSCI Rat • Post iSCIHindlimb foot rotation ↑ • r-0.878; p<0.05 • None of the other measures showed significant correlations with %GMspared Correlational analysis Conclusions Cross sectional areas of sequentially spaced sections T7 to T12. ○:Sham rats (n=3) ● iSCI rats (n=5) • %WMspared is correlated with BBB, Stance Width and Hindlimb Foot Rotation • %GMsparedis not significantly correlated with either behavioral or overground walking measures • Post-iSCI gross locomotor function is impaired primarily due to loss of axons Kinematic data measures and analysis • Stance Width: distance between the left and right heel markers • Stride Length:heel strike to heel strike on each side • Velocity (Vel): Speed at which rat is walking • Normalized Stride Length: SL/Vel • Hindlimb Foot Rotation Angle: left + right hindlimbangles (C) • Sections A0to A10 from sham rats were used to calculate the rostral factor. CFR = 1.063 • Sections A10to A19from sham rats were used to calculate the caudal factor. CFC = 0.967 • Pre-iSCI volume estimation: Rostral (CFR) and Caudal (CFC) correction factors (Rabchevskey et al) (d) References • Edgerton, V.R. and R. R. Roy, "Paralysis recovery in humans and model systems," CurrOpinNeurobiol, vol. 12, pp. 658-67, Dec 2002. E. Åkesson, C. Calzarossa, and E. Sundström, "Spinal Cord Injuries: Principles and Methods for Outcome Assessment," in Animal Models of Spinal Cord Repair. vol. 76, H. Aldskogius, Ed., ed: Humana Press, 2013, pp. 273-298. • Thota, A.K., S. C. Watson, E. Knapp, B. Thompson, and R. Jung, "Neuromechanical control of locomotion in the rat," J Neurotrauma, vol. 22, pp. 442-65, Apr 2005. • Rabchevsky, A.G., I. Fugaccia, P. G. Sullivan, and S. W. Scheff, "Cyclosporin A treatment following spinal cord injury to the rat: behavioral effects and stereological assessment of tissue sparing," J Neurotrauma, vol. 18, pp. 513-22, May 2001. Kinematic data collection setup a+b Research supported by National Institutes of Health, NCMRR (R01HD40335) and the Kentucky Spinal Cord and Head Injury Research Trust (0-9A)