Synergism of human amnion-derived multipotent progenitor (AMP) cells and a collagen scaffold in promoting brain wound recovery: pre-clinical studies in an experimental model of penetrating ballistic-like brain injury.

One of the histopathological consequences of a penetrating ballistic brain injury is the formation of a permanent cavity. In a previous study using the penetrating ballistic-like brain injury (PBBI) model, engrafted human amnion-derived multipotent progenitor (AMP) cells failed to survive when injected directly in the injury tract, suggesting that the cell survival requires a supportive matrix. In this study, we seated AMP cells in a collagen-based scaffold, injected into the injury core, and investigated cell survival and neuroprotection following PBBI. AMP cells suspended in AMP cell conditioned medium (ACCS) or in a liquefied collagen matrix were injected immediately after a PBBI along the penetrating injury tract. Injured control rats received only liquefied collagen matrix. All animals were allowed to survive two weeks. Consistent with our previous results, AMP cells suspended in ACCS failed to survive; likewise, no collagen was identified at the injury site when injected alone. In contrast, both AMP cells and the collagen were preserved in the injury cavity when injected together. In addition, AMP cells/collagen treatment preserved some apparent brain tissue in the injury cavity, and there was measurable infiltration of endogenous neural progenitor cells and astrocytes into the preserved brain tissue. AMP cells were also found to have migrated into the subventricular zone and the corpus callosum. Moreover, the AMP cell/collagen treatment significantly attenuated the PBBI-induced axonal degeneration in the corpus callosum and ipsilateral thalamus and improved motor impairment on rotarod performance. Overall, collagen-based scaffold provided a supportive matrix for AMP cell survival, migration, and neuroprotection.