Abstract
Critical size bone defects deriving from large bone loss are an unmet clinical challenge1. To account for disadvantages with clinical treatments, researchers focus on designing biological substitutes, which mimic endogenous healing through osteogenic differentiation promotion. Some studies have however suggested that this notion fails to consider the full complexity of native bone with respect to the interplay between osteoclast and osteoblasts, thus leading to the regeneration of less functional tissue2. The objective of this research is to assess the ability of our laboratory's previously developed 6-Bromoindirubin-3’-Oxime (BIO) incorporated guanosine diphosphate crosslinked chitosan scaffold in promoting multilineage differentiation of myoblastic C2C12 cells and monocytes into osteoblasts and osteoclasts1, 3, 4. BIO addition has been previously demonstrated to promote osteogenic differentiation in cell cultures5, but implementation of a co-culture model here is expected to encourage crosstalk thus further supporting differentiation, as well as the secretion of regulatory molecules and cytokines2.
Biocompatibility testing of both cell types is performed using AlamarBlue for metabolic activity, and nucleic acid staining for distribution. Osteoblastic differentiation is assessed through quantification of ALP and osteopontin secretion, as well as osteocalcin and mineralization staining. Differentiation into osteoclasts is verified using SEM and TEM, qPCR, and TRAP staining.
Cellular viability of C2C12 cells and monocytes was maintained when cultured separately in scaffolds with and without BIO for 21 days. Both scaffold variations showed a characteristic increase in ALP secretion from day 1 to 7, indicating early differentiation but BIO-incorporated sponges yielded higher values compared to controls. SEM and TEM imaging confirmed initial aggregation and fusion of monocytes on the scaffold's surface, but BIO addition appeared to result in smoother cell surfaces indicating a change in morphology. Late-stage differentiation assessment and co-culture work in the scaffold are ongoing, but initial results show promise in the material's ability to support multilineage differentiation.
Acknowledgements: The authors would like to acknowledge the financial support of the Collaborative Health Research Program (CHRP) through CIHR and NSERC, as well as Canada Research Chair – Tier 1 in Regenerative Medicine and Nanomedicine, and the FRQ-S.
