Femke Mathot

Chapter 4 60 ABSTRACT Background Differentiation of mesenchymal stem cells (MSCs) into Schwann-like cells onto processed nerve allografts may support peripheral nerve repair. The purpose of this study was to understand the biological characteristics of undifferentiated and differentiated MSCs before and after seeding onto a processed nerve allograft by comparing gene expression profiles. Methods MSCs from Lewis rats were cultured in maintenance media or differentiated into Schwann-like cells. Both treatment groups were dynamically seeded onto decellularized nerve allografts derived fromSprague-Dawley rats. Gene expressionwas quantifiedby quantitative polymerase chain reaction (qPCR) analysis of representative biomarkers, including neurotrophic ( GDNF, PTN, GAP43, PMP22 ), angiogenic ( CD31, VEGF1 ), extracellular matrix (ECM) ( COL1A1 , COL3A1 , FBLN1 , LAMB2 ) or cell cycle ( CAPS3 , CCBN2 ) genes. Gene expression values were statistically evaluated using a 2-factor ANOVA with repeated measures. Results Baseline gene expression of undifferentiated and differentiated MSCs was significantly altered upon interaction with processed nerve allografts. Interaction between processed allografts and undifferentiated MSCs enhanced expression of neurotrophic ( NGF , GDNF , PMP22 ), ECM ( FBLN1 , LAMB2 ) and regulatory cell cycle genes ( CCNB2 ) during a 7-day time course. Interactions of differentiated MSCs with nerve allografts enhanced expression of neurotrophic ( NGF , GDNF , GAP43 ), angiogenic ( VEGF1 ), ECM ( FBLN1 ) and regulatory cell cycle genes ( CASP3 , CCNB2 ) within one week. Conclusions Dynamic seeding onto processed nerve allografts modulates temporal gene expression profiles of differentiated and undifferentiated MSCs. These changes in gene expressions may support the reparative functions of MSCs in supporting nerve regeneration in different stages of axonal growth.