Transplanted MSCs injected into the subarachnoid space of the lumbar spine can migrate to injured thoracic spinal cord tissue. The ratio of MSCs observed at the injury site was significantly higher than in the intact spinal cord, and also infiltrated into the deeper spinal cord parenchyma by the perivascular spaces. Lastly, some MSCs differentiated into Nestin-positive, immature neurons or glial cells.

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Abstract:Introduction: Few studies have investigated the influence of cage subsidence patterns (intraoperative endplate injury or late-onset cage settling) on bony fusion and clinical outcomes in lateral interbody fusion (LIF). This retrospective study was performed to compare the fusion rate and clinical outcomes of cage subsidence patterns in LIF at one year after surgery.Methods: Participants included 93 patients (aged 69.0±0.8 years; 184 segments) who underwent LIF with bilateral pedicle screw fixation. All segments were evaluated by computed tomography and classified into three groups: Segment E (intraoperative endplate injury, identified immediately postoperatively); Segment S (late-onset settling, identified at 3 months or later); or Segment N (no subsidence). We compared patient characteristics, surgical parameters and fusion status at 1 year for the three subsidence groups. Patients were classified into four groups: Group E (at least one Segment E), Group S (at least one Segment S), Group ES (both Segments E and S), or Group N (Segment N alone). Visual analog scales (VASs) and the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) were compared for the four patient groups.Results: 184 segments were classified: 31 as Segment E (16.8%), 21 as Segment S (11.4%), and 132 as Segment N (71.7%). Segment E demonstrated significantly lower bone mineral density (-1.7 SD of T-score, p=0.003). Segment S demonstrated a significantly higher rate of polyetheretherketone (PEEK) cages (100%, p=0.03) and a significantly lower fusion rate (23.8%, p=0.01). There were no significant differences in VAS or in any of the JOABPEQ domains among the four patient groups.Conclusions: Intraoperative endplate injury was significantly related to bone quality, and late-onset settling was related to PEEK cages. Late-onset settling demonstrated a worse fusion rate. However, there were no significant differences in clinical outcomes among the subsidence patterns.

We investigated the temporal and spatial expression patterns of the GDNF gene after subjecting rats to an acute contusion injury of the spinal cord using the weight drop technique. Reverse transcriptase-polymerase chain reaction (RT-PCR) revealed that GDNF transcription in the spinal cord began to increase within 30 min after injury and peaked within 3 h. Immunohistochemical analysis showed GDNF immunoreactivity to be present mainly in microglia and macrophages 1 day after injury, but not in neurons or astrocytes. This immediate upregulation of GDNF gene expression may be a component of an inflammatory process and probably exerts a protective effect on neurons following spinal cord injury (SCI).

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