Prx1 + MPCs Accumulate in the Dura Mater of Wild-Type and p21 -/- Mice Followed by a Specific Reduction in p21 -/- Dural MPCs.

Epidural fat contains a population of mesenchymal progenitor cells (MPCs), and this study explores the behavior of these cells on the adjacent dura mater during growth and in response to injury in a p21 knockout mouse model. p21 -/- mice are known to have increased cell proliferation and enhanced tissue regeneration post-injury. Therefore, it is hypothesized that the process by which epidural fat MPCs maintain the dura mater can be accelerated in p21 -/- mice. Using a Prx1 lineage tracing mouse model, the epidural fat MPCs are found to increase in the dura mater over time in both C57BL/6 (p21 +/+ ) and p21 -/- mice; however, by 3 weeks post-tamoxifen induction, few MPCs are observed in p21 -/- mice. These endogenous MPCs also localize to dural injuries in both mouse strains, with MPCs in p21 -/- mice demonstrating increased proliferation. When epidural fat MPCs derived from p21 -/- mice are transplanted into dural injuries in C57BL/6 mice, these MPCs are found in the injury site. It is demonstrated that epidural fat MPCs play a role in dural tissue maintenance and are able to directly contribute to dural injury repair. This suggests that these MPCs have the potential to treat injuries and/or pathologies in tissues surrounding the spinal cord.