Effect of pore characteristics on mechanical properties and annulus fibrosus cell seeding and proliferation in designed PTMC tissue engineering scaffolds

Degeneration of the intervertebral disk is the main cause of chronic back pain. Disk degeneration often leads to tearing of the annulus fibrosus (AF) and extrusion of the nucleus pulposus. As the current surgical strategies are suboptimal, reconstruction of the AF tissue by a tissue engineering strategy has emerged as an alternative. However, regeneration of the AF is challenging due to its complex and non-homogeneous structure. Since there is a lack of knowledge regarding the effects of scaffold pore sizes on the behavior of human AF cells (hAFCs), scaffolds with a well-defined and controlled pore architecture with pore sizes ranging from 230–420 µm were prepared by stereolithography. The scaffolds were prepared from the crosslinked biodegradable elastomer poly(trimethylene carbonate) (PTMC). The compression modulus of the scaffolds was inversely related to the pore size and ranged from 0.31–0.21 MPa. These values are similar to those reported for native AF tissue. Seeded hAFCs adhered to the PTMC network and proliferated well in all scaffolds during a culture period of 14 days. However, cell distribution was less homogeneous in the scaffold with 230 µm pore size. In view of its relatively high stifness, the latter scaffold is most suitable for AF tissue engineering, provided that the cell seeding procedure in this scaffold is optimized