Fate of Transplanted Allogeneic Mesenchymal Stromal Cells in the Rat Spinal Cord under Normal Conditions and during the Acute Phase of Spinal Cord Contusion Injury.

We studied the distribution and survival of mesenchymal stem cells (MSCs) transplanted within a fibrin hydrogel into the spinal cord of immunocompetent rats without spinal cord injury (SCI) and with contusion SCI within the first hours after injury. MSC migration was monitored by MRI, and cell survival was assessed by immunofluorescence and immunohistochemistry on spinal cord sections. It was shown that transplanted allogeneic MSCs remain viable for at least 7 days in case of intrafocal administration 30 min after experimental contusion SCI and for at least 28 days in case of subdural and intramedullary transplantation into the intact spinal cord. MSCs are predominantly located at the injection site. Thus, our data demonstrate that allogeneic MSCs transplanted into the SCI site in the acute phase can survive for at least 7 days without migrating into surrounding tissues.