Femke Mathot

Chapter 9 144 ABSTRACT Background As the functional outcome of clinically available nerve graft substitutes remains inadequate to replace the use of autograft nerves in peripheral nerve injuries, it was hypothesized that Mesenchymal Stem Cells (MSCs) could provide the necessary trophic factors when seeded onto the surfaces of these commonly used nerve graft substitutes. We aimed to determine the gene expression of MSCs when influenced by Avance® Nerve Grafts or NeuraGen® Nerve Guides. Methods Human adipose derived MSCs were cultured and dynamically seeded onto 30 Avance® Nerve Grafts and 30 NeuraGen® Nerve Guides for 12 hours. At 6 different time points after seeding, qPCR analyses were performed for 5 samples per group. Neurotrophic (NGF, GDNF, PTN, GAP43, BDNF), myelination (PMP22 and MPZ), angiogenic (VEGF-a and PECAM1/CD31), extracellular matrix (ECM) (COL1A1, COL3A1, FBLN1, LAMB2) and cell surface marker (CD96) gene expressions were quantified. Unseeded Avance® Nerve Grafts and NeuraGen® Nerve Guides were used to evaluate the baseline gene expression, and unseeded MSCs provided the reference gene expression of MSCs. Results The interaction of MSCs with the Avance® Nerve Grafts led to a short-term upregulation of neurotrophic (NGF, GDNF and BDNF), myelination (PMP22 and MPZ) and angiogenic genes (CD31 and VEGF-a) and a long-term upregulation of BDNF, VEGF-a and COL1A1. The interaction between MSCs and the NeuraGen® Nerve Guide led to short term upregulation of neurotrophic (NGF, GDNF and BDNF) myelination (PMP22 and MPZ), angiogenic (CD31 and VEGF-a), ECM (COL1A1) and cell surface (CD96) genes and long-term upregulation of neurotrophic (GDNF and BDNF), angiogenic (CD31 and VEGF-a), ECM genes (COL1A1, COL3A1, FBLN1) and cell surface (CD96) genes. Analysis demonstrated MSCs seeded onto NeuraGen® Nerve Guides expressed significantly higher levels of neurotrophic (PTN), angiogenic (VEGF-a) and ECM (COL3A1, FBLN1) genes on the long term compared to MSCs seeded onto Avance® Nerve Grafts. Conclusion The interaction between human MSCs and Avance® Nerve Grafts and NeuraGen® Nerve Guides resulted in a significant upregulation of the expression of numerous genes important for nerve regeneration over time. The in vitro interaction of MSCs with the NeuraGen® Nerve Guide was more pronounced, particularly in the long term (>14 days after seeding). These results suggest that MSC-seeding has potential to be applied in a clinical setting, which needs to be confirmed in future in vitro and in vivo research.