Comparative evaluation of mesenchymal stromal cell growth and osteogenic differentiation on a shape memory polymer scaffold

Trauma-induced, critical-size bone defects pose a clinical challenge to heal. Albeit autografts are the standard-of-care, they are limited by their inability to be shaped to various defect geometries and often incur donor site complications. Herein, the combination of a "self-fitting" shape memory polymer (SMP) scaffold and seeded mesenchymal stromal cells (MSCs) was investigated as an alternative. The porous SMP scaffold, prepared from poly(epsilon-caprolactone) diacrylate (PCL-DA) and coated with polydopamine, provided conformal shaping and cell adhesion. MSCs from five tissues, amniotic (AMSCs), chorionic tissue (CHSCs), umbilical cord (UCSCs), adipose (ADSCs), and bone marrow (BMSCs) were evaluated for viability, density, and osteogenic differentiation on the SMP scaffold. BMSCs exhibited the fastest increase in cell density by day 3, but after day 10, CHSCs, UCSCs, and ADSCs approached similar cell density. BMSCs also showed the greatest calcification among the cell types, followed closely by ADSCs, CHSCs and AMSCs. Alkaline phosphatase (ALP) activity peaked at day 7 for AMSCs, UCSCs, ADSCs and BMSCs, and at day 14 for CHSCs, which had the greatest overall ALP activity. Of all the cell types, only scaffolds cultured with ADSCs in osteogenic media had increased hardness and local modulus as compared to blank scaffolds after 21 days of cell culture and osteogenic differentiation. Overall, ADSCs performed most favorably on the SMP scaffold. The SMP scaffold was able to support key cellular behaviors of MSCs and could potentially be a viable, regenerative alternative to autograft.