Effective cavity-filling effect by transplanted cells in SCI HSSC-injected animals. At the end of the two-month post-treatment survival, animals were perfusion fixed with 4% PFA, the spinal column dissected and MRI-imaged in situ before spinal cord dissection for further histological processing. A, B: Three-dimensional MRI images of spinal cord segments in animals with previous traumatic injury and treated with spinal HSSC (A) or media (B) injections. Note the near complete injected-cells cavity-filling effect in HSSC-treated animals. A1, A2, B1, B2: To validate the presence of grafted cells or cavitation at the epicenter of injury, the same region was histologically processed, semi-thin plastic sections prepared and compared to the corresponding MRI image (compare A1 to A2 and B1 to B2). C: Two-dimensional MRI image taken from a naïve-non-injured animal. D: Quantification of the cavity and scar volume from serial MRI images showed significantly decreased cavity and scar volumes in SCI-HSSC-injected animals if compared to media-injected SCI controls. (D: data expressed as mean ± SEM; Student t- tests), (Scale Bars: A, B: 5 mm; A1, A2, B1, B2, C: 3 mm). HSSC, human fetal spinal cord-derived neural stem cells; MRI, magnetic resonance imaging; PFA, paraformaldehyde; SCI, spinal cord injury; SEM, standard error of the mean.