Journal of Undergraduate Research
Volume 3, Issue 7 - April 2002

Effects of Spinal Cord Injury and Fetal Tissue Transplantation on Bipedal Locomotion in Cats

Nicholas Schindler

ABSTRACT

The present study quantitatively examined bipedal locomotion from the side and rear views to determine the effects of spinal cord injury and intraspinal fetal tissue transplantation on weight support and balance in the cat. Following a spinal cord compression injury and a subsequent behavioral plateau, four of seven cats received an injection of fetal tissue into the lesion, while the other three cats were injected with the vehicle alone. The subjects were filmed walking on the treadmill at variable speeds and at three different time intervals: pre-operative, late post-injury, and late post-injection.

This investigation found that spinal cord injury resulted in an increased stance width, angle of hindquarter sway, and angle of lateral stability. The stride length and height of the animals changed inconsistently. Transplantation had several individual effects on locomotion, but there were no general trends among all cats that deviated from post-injury data.

INTRODUCTION

Spinal cord injury (SCI) is a physical, emotional, and financial devastation that affects approximately 250,000 people in the United States alone, with 10,000 additional injuries occurring each year [1]. Recovery of locomotor function following SCI has been a major focus of neurological research. Several potentially beneficial treatments are being examined, intended to help both the acutely injured and those afflicted with a chronic spinal cord injury. A treatment being investigated by many laboratories, and the focus of the present study, is transplantation of fetal neural tissue into the spinal cord lesion to enhance recovery of function. Fetal tissue transplantation has shown positive effects in previous SCI investigations [2,3,4]. To assess the effects of SCI treatments on locomotion, reliable and comprehensive tests are necessary. The present study quantitatively examined bipedal locomotion from the side and rear views to determine the effects of spinal cord injury and intraspinal fetal tissue transplantation on weight support and balance in the cat. The compression injury model was selected for this study because it is comparable to SCI in humans [5].

METHODS

Subjects


Seven spayed adult female cats (Liberty Research, Inc.), weighing 3-4 kg, served as subjects. All procedures were approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Florida.

Data Collection


Each cat was trained to walk on a motorized treadmill with the forelegs resting on a support board while the hindlegs paced the treadmill surface. The cats were fed continuously while walking via a pneumatic pump that propelled blended cat food through plastic tubing, ending in a funnel. Every two months the animals were filmed from the rear and side views at walking speeds 0.2, 0.5, and 0.8 m/s.

Surgery

After the cats were trained and filmed walking on the treadmill, each animal underwent a 200-gram thoracic (T12) compression injury of the spinal cord. Following a behavioral plateau (6-8 months post-injury), four cats (kl, ph, co, rg) received an intraspinal injection into the cystic cavity of solid grafts of fetal spinal cord tissue (E20 to E22) suspended in a glucose-saline solution. The other three cats (jb, jy, gn) were injected with the glucose-saline solution alone. Cyclosporine A (Sandoz Pharmaceutical Co.) was administered (10 mg/kg, p.o.) to each cat two days prior to intraspinal injection and daily thereafter for seven weeks. The animals were anesthetized with Isoflurane gas throughout each of the surgeries; heart and respiratory rates were closely monitored. Penicillin-G (1.0 cc, s.c.) was administered the day prior to and of surgery. Buprenorphine (0.2 cc, s.c.) was injected immediately following surgery and every four hours as needed for pain. Injuries were performed by W. O'Steen, ovarihysterectomies by Dr. H. Ramirez, fetal tissue dissection by B. O'Steen, and fetal tissue transplantation by Dr. P. Reier.

Image Analysis


Bipedal locomotion was examined at the following three critical filming sessions: pre-operative, late post-injury, and late post-injection. Images of the side and rear views were captured onto a computer from the recorded VHS film using image analysis software (Image-Pro Plus, Version 4.1). Three phases of the step cycle for each hindlimb were analyzed: rostral ankle extension (E1; Fig. 1), caudal ankle extension (E3; Fig. 2), and maximum flexion as indicated by the height of the foot (F; Fig. 3). The step phases for each hind leg were captured in the following order: E1L, E3R, FR, E1R, E3L, and FL (e.g. E1L signifies the left leg in E1 phase). Ten complete step cycles were analyzed for each walking speed.

Figure 1. Side view illustration of a cat with its right leg in E1 phase of the step cycle. The measurements analyzed from the side view include length of the treadmill (a), the length of the cat measured from base of the tail to between the shoulder blades (b), the height of the cat measured from the base of the tail to the treadmill surface (c), and the distance between the hindfeet, also known as the stride length (d).

Figure 1. Side view illustration of a cat with its right leg in E1 phase of the step cycle. The measurements analyzed from the side view include length of the treadmill (a), the length of the cat measured from base of the tail to between the shoulder blades (b), the height of the cat measured from the base of the tail to the treadmill surface (c), and the distance between the hindfeet, also known as the stride length (d).

Figure 2. Side view illustration of a cat with its right leg in E3 phase of the step cycle.

Figure 2. Side view illustration of a cat with its right leg in E3 phase of the step cycle.

Figure 3. Side view illustration of a cat with its right leg in flexion (F) phase of the step cycle.

Figure 3. Side view illustration of a cat with its right leg in flexion (F) phase of the step cycle.

From the side view, the following were measured from each captured digital image in pixels (illustrated in Fig. 1): length of the treadmill, length of the animal from the middle of the shoulder blades to the base of the tail, height (distance from the base of the tail to the treadmill), and stride length (distance between the hindfeet). From the rear view, the width of the treadmill, the distance that the base of the tail moved from the midline during each step phase, and stance width (distance between the hindfeet) were measured (Fig. 4). Using the width and length of the treadmill in pixels and the actual width and length of the treadmill in centimeters, a simple proportion was applied to convert each of the measurements from pixels to centimeters. From the measurements in centimeters, the angle of hindquarter sway (Fig. 5) and angle of lateral stability (Fig. 6) were calculated.

Figure 4. Rear view illustration of a cat with its left leg in flexion (F) phase of the step cycle. The measurements analyzed from the rear view include the width of the treadmill (a), the distance between the midline and the base of the tail (b), and the distance between the feet, known as stance width (c). The midline (d) was determined by creating a line perpendicular to the distance between the forefeet (e), such that the midline was equidistance between the forefeet.

Figure 4. Rear view illustration of a cat with its left leg in flexion (F) phase of the step cycle. The measurements analyzed from the rear view include the width of the treadmill (a), the distance between the midline and the base of the tail (b), and the distance between the feet, known as stance width (c). The midline (d) was determined by creating a line perpendicular to the distance between the forefeet (e), such that the midline was equidistance between the forefeet.

Figure 5. Diagram of the top view showing the angle of sway (8), as calculated fromthe length of the cat (a) and the distance that the animal's trunk moved away from the midline (b).

Figure 5. Diagram of the top view showing the angle of sway (8), as calculated fromthe length of the cat (a) and the distance that the animal's trunk moved away from the midline (b).

Figure 6. Top view of the hindfeet of a cat on a treadmill, illustrating the distances between the hindfeet, as seen from the rear (a) and side (b) views. Also shown is the angle of lateral stability (8).

Figure 6. Top view of the hindfeet of a cat on a treadmill, illustrating the distances between the hindfeet, as seen from the rear (a) and side (b) views. Also shown is the angle of lateral stability (8).

Statistics

The measurements and calculations were analyzed using analysis of variance (ANOVA) to find the individual effects between the three filming sessions. Subsequent analyses were performed using Duncan's post-hoc test. Results were regarded as statistically significant when p < 0.05.

RESULTS

During the recovery periods, each cat required external weight support while walking on the treadmill. Five of the seven cats regained independent locomotion approximately one to two months post-injury, however, two cats continued to require external weight support for over eight months post-injury and this condition did not change post-injection. Additionally, one of the cats (co) who could walk on the treadmill without weight support post-injury required weight support at the behavioral plateau post-transplant. The external weight support altered the cats' locomotion and affected the measurements analyzed in the study. Therefore, those cats requiring weight support were not included in the image analysis.

Injury Effects


The average stance width was significantly larger post-injury during all step phases at treadmill speeds of 0.2 m/s (Table 1A; Fig. 7A) and 0.5 m/s (Table 2A; Fig. 8A). At the 0.8 m/s speed, however, two cats had a smaller stance width post-injury, two had a larger stance width, and one cat had no significant difference (Table 3A; Fig. 9A). There was an increase in the degree of sway post-injury during the E3 phase at all three treadmill speeds (Tables 1D, 2D, 3D; Figs. 7D, 8D, 9D). There was also an overall larger angle of lateral stability post-injury, especially during the extension phases at 0.2 m/s (Table 1E; Fig. 7E) and 0.5 m/s (Table 2E; Fig. 8E).

Table 1
ANOVA and post-hoc results for individual cats, comparing pre-op, post-injury, and post transplant at speed 0.2 m/s
A - Stance width B - Stride Length C - Height D - Angle of sway E - Angle of Lateral stability
Type
ANOVA
Duncan's post-hoc tests: p* <
F (2, 27) =
p* <
pre-op vs. post-injury
pre-op vs. post-injection
post-injury vs. post-injection
kl
jb
ph
jy
co**
kl
jb
ph
jy
co
kl
jb
ph
jy
kl
jb
ph
jy
kl
jb
ph
jy
A E1L 6.76 8.584 79.87 110.2 1456 0.004 0.001 0.001 0.001 0.001 0.003 0.001 0.001 0.001 0.01 0.01 0.001 0.001 - - 0.038 0.016
A E3R 10.91 24.77 114.7 73.54 1196 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.003 0.001 0.001 0.001 - - 0.033 -
A FR 74.93 65.44 160.8 161.2 1511 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.018 0.009 - -
A E1R 24.68 35.64 84.05 95.81 935.0 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.02 - - 0.001
A E3L 16.03 24.89 48.18 88.8 1186 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.003 - 0.001
A FL 31.9 43.89 64.4 151.6 767 0.001 0.001 0.001 0.001 0.001 0.001 0.004 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001
B E1L 86.93 33.81 7.094 21.54 5,244 0.001 0.001 0.003 0.001 0.034 0.001 0.001 0.005 0.001 0.001 0.001 0.003 - - 0.006 - 0.001
B E3R 85.85 44.76 4.736 24.42 0.381 0.001 0.001 0.017 0.001 - 0.001 0.001 0.019 0.001 0.001 0.001 0.013 - - 0.018 - 0.001
B FR 9.34 53.55 1.567 42.06 49.78 0.001 0.001 - 0.001 0.001 - 0.001 - - 0.001 0.001 - 0.001 0.001 - - 0.001
B E1R 68.01 13.42 6.212 105.2 4.262 0.001 0.001 0.006 0.001 - 0.001 0.001 0.002 0.038 0.001 0.013 - 0.001 - 0.018 - 0.001
B E3L 62.56 10.46 3.314 67.77 27.48 0.001 0.001 - 0.001 0.001 0.001 0.001 - - 0.001 - - 0.001 - 0.004 - 0.001
B FL 2.25 9.518 7.255 7.525 1.457 - 0.001 0.003 0.003 - - 0.025 0.005 0.022 - - 0.003 0.001 - 0.001 - -
C E1L 7.61 2.238 295 29.2 29.2 0.493 0.002 - 0.001 - - - 0.001 0.002 0.005 - 0.001 0.001 0.002 - 0.001 0.001
C E3R 3.63 11.09 136.2 40.91 40.91 0.5 0.04 0.001 0.001 - - 0.001 0.001 0.018 0.033 - 0.001 0.001 0.003 0.004 0.001 0.001
C FR 11.94 16.33 110 105.3 105.3 4.128 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 - - 0.001 0.001 0.001 0.001 0.005 0.001
C E1R 22.78 15.16 126 72.71 72.71 4.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.005 - 0.001 0.001 0.001 0.001 - 0.001
C E3L 107 9.621 105.1 73.37 73.37 17.2 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 - 0.007 - 0.001
C FL 1.95 5.37 188.7 77.95 77.95 7.493 - 0.011 0.001 0.014 - 0.007 0.001 0.001 - - 0.001 0.001 - 0.08 0.001 0.001
D E1 2.53 10.36 4.353 6.051 92.46 - 0.001 0.023 0.007 0.001 - 0.001 0.018 - - 0.001 - 0.003 - - 0.021 0.043
D E3 13.81 31.04 10.49 23.01 32.72 0.001 0.001 0.001 0.001 0.001 0.011 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.019 0.007 - 0.038
D F 48.69 17.49 1.376 11.49 0.33 0.001 0.001 - 0.001 - 0.001 0.001 - 0.001 0.001 0.024 - - 0.019 0.002 - 0.001
E E1L 25.19 34.44 4.19 20.63 243.3 0.001 0.001 0.026 0.001 0.001 0.001 0.001 0.039 - 0.001 0.001 0.014 0.001 - 0.027 - 0.001
E E3R 20.03 51.66 11.6 18.27 144.9 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 - 0.021 - 0.001
E FR 6.99 52.88 0.431 19.12 4.423 0.004 0.001 - 0.001 0.05 - 0.001 - 0.004 0.012 0.001 - 0.005 0.002 - - 0.001
E E1R 68.76 3.502 11.55 30.12 623.9 0.001 0.045 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.018 0.001 0.003 0.013 - - 0.001
E E3L 28.62 0.922 8.999 26.91 1251 0.001 - 0.001 0.001 0.001 0.001 - 0.002 0.001 0.001 - 0.001 0.001 - - - 0.002
E FL 7.4 5.445 6.07 0.677 0.641 0.003 0.01 0.007 - - 0.001 - 0.008 - - - 0.005 - 0.012 0.004 - -
* a dash (-) signifies a p-value > 0.05
** post-injection data was not analyzed for cat co , so df = (1, 18).

Figure 7. Graphs comparing average pre-operative and post-injury measurements during bipedal walking speed 0.2m/s. The step phase is on the x-axis in all figures. Error bars express +/- SEM.

Figure 7. Graphs comparing average pre-operative and post-injury measurements during bipedal walking speed 0.2m/s. The step phase is on the x-axis in all figures. Error bars express +/- SEM.

Table 2
ANOVA and post-hoc results for individual cats, comparing pre-op, post-injury, and post transplant at speed 0.5 m/s
A - Stance width B - Stride Length C - Height D - Angle of sway E - Angle of Lateral stability
Type
ANOVA
Duncan's post-hoc tests: p* <
F (2, 27) =
p* <
pre-op vs. post-injury
pre-op vs. post-injection
post-injury vs. post-injection
kl
jb
ph
jy
co**
kl
jb
ph
jy
co
kl
jb
ph
jy
kl
jb
ph
jy
kl
jb
ph
jy
A E1L 38.06 11.51 50.55 150.6 619.5 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 - 0.03
A E3R 167.2 4.696 55.15 79.83 812.4 0.001 0.018 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.012 0.001 0.001 0.001 0.02 0.014 -
A FR 32.05 0.582 54.06 142.1 732.1 0.001 - 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 - 0.001 0.001 - - - 0.001
A E1R 84.01 2.851 58.89 151 664.5 0.001 - 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 - 0.001 0.001 0.001 - 0.038 0.001
A E3L 27.56 1.566 48.42 180.5 673.6 0.001 - 0.001 0.001 0.001 0.001 - 0.001 0.001 0.002 - 0.001 0.001 0.001 - - 0.001
A FL 85.82 23.95 134.4 131.1 959.8 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001
B E1L 141.1 1.527 8.979 1.588 30.63 0.001 - 0.001 - 0.001 0.001 - 0.001 - 0.001 - 0.015 - 0.001 - - -
B E3R 4.308 28.17 76.07 83.91 41.59 0.024 0.001 0.001 0.001 0.001 - 0.001 0.001 - 0.038 0.01 0.001 0.001 0.013 0.001 - 0.001
B FR 24.85 3.435 79.33 176.5 70.15 0.001 0.047 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 - 0.001 0.001 - 0.027 0.006 0.001
B E1R 161.2 57.07 41.6 52.77 30.04 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.034 0.001 - 0.001 0.001 0.016 0.001 0.001 0.001
B E3L 467.6 56.91 36.96 32.37 2.26 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.047 0.001 0.002 0.001 0.001 0.001 0.001 0.002 0.001
B FL 19 74.3 141 160.3 32.18 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 - 0.001
C E1L 6.899 9.786 11.36 7.528 77.98 0.004 0.001 0.001 0.003 0.001 - 0.001 0.001 - 0.001 - 0.001 0.002 0.032 0.022 - 0.005
C E3R 3.63 11.09 136.2 40.91 40.91 0.5 0.04 0.001 0.001 - - 0.001 0.001 0.018 0.033 - 0.001 0.001 0.003 0.004 0.001 0.001
C FR 11.94 16.33 110 105.3 105.3 4.128 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 - - 0.001 0.001 0.001 0.001 0.005 0.001
C E1R 22.78 15.16 126 72.71 72.71 4.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.005 - 0.001 0.001 0.001 0.001 - 0.001
C E3L 107 9.621 105.1 73.37 73.37 17.2 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 - 0.007 - 0.001
C FL 1.95 5.37 188.7 77.95 77.95 7.493 - 0.011 0.001 0.014 - 0.007 0.001 0.001 - - 0.001 0.001 - 0.08 0.001 0.001
D E1 2.53 10.36 4.353 6.051 92.46 - 0.001 0.023 0.007 0.001 - 0.001 0.018 - - 0.001 - 0.003 - - 0.021 0.043
D E3 22.66 37.88 35.69 98.85 47.76 0.001 0.001 0.001 0.001 0.001 0.011 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - - - 0.001
D F 16.58 18.09 3.073 5.986 1.096 0.001 0.001 - 0.007 - 0.001 0.001 - 0.003 - - - 0.038 0.001 0.001 - -
E E1L 204 4.554 72.72 57.27 184.6 0.001 0.02 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.008 0.001 0.001 0.025 - 0.001 -
E E3R 298.8 5.519 63.22 38.59 158.8 0.001 0.01 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.004 0.001 0.001 0.001 - 0.001 0.001
E FR 23.05 4.882 7.179 5.163 7.542 0.001 0.016 0.003 0.013 0.013 0.001 0.006 0.001 0.033 - - 0.019 0.006 0.001 - - -
E E1R 10.43 27.74 30.9 35.17 231.4 0.001 0.001 0.001 0.001 0.001 0.009 0.001 0.001 0.001 - 0.007 0.001 0.001 0.001 0.001 - -
E E3L 9.133 29.68 32.98 35.62 285.3 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.014 0.003 - -
E FL 38.53 1.669 0.28 0.12 0.43 0.001 - - - - 0.001 - - - 0.001 - - - 0.001 - - -
* a dash (-) signifies a p-value > 0.05
** post-injection data was not analyzed for cat co , so df = (1, 18).

Figure 8. Graphs comparing average pre-operative and post-injury measurements during bipedal walking speed 0.5 m/s. The step phase is on the x-axis in all figures. Error bars express +/- SEM.

Figure 8. Graphs comparing average pre-operative and post-injury measurements during bipedal walking speed 0.5 m/s. The step phase is on the x-axis in all figures. Error bars express +/- SEM.

Table 3
ANOVA and post-hoc results for individual cats, comparing pre-op, post-injury, and post transplant at speed 0.8 m/s
A - Stance width B - Stride length C - Height D - Angle of sway E - Angle of Lateral stability
Type
ANOVA
Duncan's post-hoc tests: p* <
F (2, 27) =
p* <
pre-op vs. post-injury
pre-op vs. post-injection
post-injury vs. post-injection
kl
jb
ph
jy
co**
kl
jb
ph
jy
co
kl
jb
ph
jy
kl
jb
ph
jy
kl
jb
ph
jy
A E1L 272.9 148.1 55.84 66.48 6.708 0.001 0.001 0.001 0.001 0.019 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.022
A E3R 144.1 234.8 34.18 95.43 0.039 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001
A FR 184.9 99.28 76.32 31.97 6.31 0.001 0.001 0.001 0.001   0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.004 0.016
A E1R 148.9 189.1 68.19 69.14 0.106 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.015 0.001
A E3L 111.2 242.9 41.07 134.3 6.889 0.001 0.001 0.001 0.001   0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001
A FL 75.43 311.2 94.28 33.44 27.89 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - - 0.001 -
B E1L 31.18 11.22 10.14 0.255 2.043 0.001 0.001 0.001 - - 0.001 0.001 0.001 - 0.001 0.001 0.003 - - - - -
B E3R 8.666 0.246 34.89 7.896 19.43 0.001 - 0.001 0.002 0.001 0.031 - 0.001 - 0.001 - 0.001 0.004 - - - 0.002
B FR 64.66 5.564 7.062 43.4 114.5 0.001 0.01 0.003 0.001 0.001 0.001   0.002 0.001 0.001 0.012 0.018 0.001 - - - 0.001
B E1R 9.881 15.58 6.811 46.76 98.19 0.001 0.001 0.004 0.001 0.001 0.001 0.001 - 0.001 - 0.006 0.018 0.001 0.002 0.016 0.002 0.046
B E3L 23.9 43.61 41 10.59 116.5 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.008 0.001 0.001 -
B FL 10.62 7.128 0.639 3.755 4.331 0.001 0.003 - 0.036 - 0.035 0.038 - - 0.001 - - 0.016 0.025 0.001 - -
C E1L 2.478 1.362 106.1 403.7 384 - - 0.001 0.001 0.001 - - 0.001 0.004 - - 0.001 0.001 - - - 0.001
C E3R 11.93 1.384 175.9 190.2 93.07 0.001 - 0.001 0.001 0.001 0.001 - 0.001 - - - 0.001 0.001 0.001 - 0.003 0.001
C FR 102.2 40.08 288.2 529.4 206.1 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - - 0.001 0.001
C E1R 139.9 22.16 77.89 134.5 77.36 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 - 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001
C E3L 68.26 4.314 38.87 115.8 6.264 0.001 0.024 0.001 0.001 0.022 0.001 0.012 0.001 - 0.001 - - 0.001 - 0.045 0.001 0.001
C FL 61.91 1.105 60.26 315.6 644.5 0.001 - 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 - 0.001 0.001 - - 0.006 0.001
D E1 2.684 1.053 50.15 0.211 19.44 - - 0.001 - 0.001 - - 0.001 - - - 0.001 - - - 0.017 -
D E3 23.64 12.07 37.46 36.39 23.7 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.001 0.003 0.001 - -
D F 9.143 26.09 10.58 1.503 0.645 0.001 0.001 0.001 - - 0.001 0.001 0.001 - - 0.001 0.001 - 0.008 0.004 - -
E E1L 186.5 135.6 51.43 42.27 2.602 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.002 0.001 0.002 -
E E3R 67.05 135 54.81 37.95 1.169 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001
E FR 324.1 21.94 3.261 25.12 44.76 0.001 0.001 - 0.001 0.001 0.001 0.001 - 0.001 0.001 0.001 - 0.001 - 0.013 - 0.014
E E1R 49.57 163.9 6.141 32.55 3.981 0.001 0.001 0.006 0.001 - 0.001 0.001 - 0.001 0.001 0.001 0.003 0.001 0.001 0.001 0.038 0.003
E E3L 6.997 220.2 39.83 40.69 18.5 0.004 0.001 0.001 0.001 0.001 0.008 0.001 0.003 0.001 - 0.001 0.001 0.001 0.002 0.001 0.001 0.002
E FL 23.15 12.49 0.689 1.057 0.413 0.001 0.001 - - - 0.001 - - - 0.001 0.001 - - - 0.001 - -
* a dash (-) signifies a p-value > 0.05
** post-injection data was not analyzed for cat co , so df = (1, 18).

Figure 9. Graphs comparing average pre-operative and post-injury measurements during bipedal walking speed 0.8 m/s. The step phase is on the x-axis in all figures. Error bars express +/- SEM.

Figure 9. Graphs comparing average pre-operative and post-injury measurements during bipedal walking speed 0.8 m/s. The step phase is on the x-axis in all figures. Error bars express +/- SEM.

The stride length (Table 1B; Fig. 7B) changed inconsistently from pre-op to post-injury. During E1L and E3R, three cats had a significantly larger stride length and two had a smaller stride length. During E1R and E3L, however, one cat had a shorter stride length and the others had a longer stride length. The heights (Table 1C; Fig. 7C) also varied post-injury: the height of two cats decreased, two other cats had an increased height, and another had approximately no change from pre-op to post-injury.

Transplant Effects


Since there were only two cats injected with transplants and two injected with vehicles that could be analyzed, the effects of fetal tissue transplantation on locomotion were examined on an individual basis. The main difference for cat kl was a larger degree of sway post-transplant (Tables 1D, 2D, 3D), which deviated further from the pre-op values. Cat ph had a larger stance width post-transplant at 0.8 m/s (Table 3A). After intraspinal injection of the vehicle, cat jb had a decreased stride length (Table 1B), increased height (Tables 1C, 2C), and increased degree of sway (Tables 1D, 3D). Cat jy also received a vehicle injection and subsequently walked with an increased stance width (Tables 1A, 2A, 3A), increased stride length (Tables 1B, 2B, 3B), and increased angle of sway (Tables 1D, 2D), all of which further differed from pre-operative values.

DISCUSSION

Injury Effects


The increase in stance width that occurred post-injury was likely a result of compensatory mechanisms to account for a partial loss of supraspinal input, which affects finer details of locomotion such as balance and coordination [6]. The larger degree of hindquarter sway was further indicative of less balance post-injury and post-injection. The specific pathways affected by injury, however, cannot be determined solely on the basis of behavior. The height of the cats had more to do with weight support than balance, although an increase in height might have been caused by generalized hyperreflexia that commonly occurs following SCI, which involves exaggerated stretch reflexes and cutaneous reflexes [7]. Hyperreflexia could have prevented the animal from having full range of motion of the limbs, resulting in a rigid posture and increased height. The larger angle of lateral stability post-injury resulted from a greater increase in stance width than increase in stride length. A greater angle of lateral stability, theoretically, correlates with a more stable posture since the body is more stabilized with the legs side-by-side than one in front of another. Thus, an increase in this angle indicated a compensation for less balance.

Transplant Effects


The fetal tissue transplantation data cannot be accurately interpreted due to the variability, small sample size, and lack of significant overall improvement between post-injury and post-injection locomotion patterns. Without histological information, one cannot be certain whether or not the transplant survived, integrated with host tissue, or enhanced recovery of function.

Conclusions


It is recognized that fetal tissue transplantation might not be a feasible treatment option for human SCI; however, it is important experimentally for a better understanding of SCI and future SCI treatments. While the present study could not detect many effects of fetal tissue transplantation on locomotion in adult chronic SCI cats, forthcoming studies of the histology should reveal the extent of tissue integration. Nonetheless, this investigation provided a more detailed insight into the bipedal locomotion patterns that result from compression injury. These concepts of analysis, especially the utilization of the rear view to determine stance width and degree of sway, could be applicable to future studies examining the effects of SCI treatments on locomotion.

ACKNOWLEDGEMENTS

I sincerely thank Dr. Charles Vierck, Jacquie Rodgers, Kristin Stevens, Dr. Paul Reier, Wilbur and Barbara O'Steen, Dr. Louis Ritz, Dr. Harvey Ramirez, Dr. Thomas Mareci, and the University Scholars Program. This investigation was funded by NIH Grant # NS35702, Cellular Repair of the Injured Spinal Cord.

REFERENCES

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