An in vitro analysis of injectable methacrylated alginate cryogels incorporated with PRP targeting minimally invasive treatment of bone nonunion

The macroporous structure and high interconnectivity of cryogels supports fluid flow, cell mobility, and angiogenesis throughout the scaffold. Additionally, a pre-formed injectable cryogel allows the potential for minimally invasive treatment of bone nonunions that would normally require surgical intervention. Such a defect is due to compromised signaling pathways by biological or biomechanical disturbance during fracture healing. The addition of powdered platelet-rich plasma (PRP) introduces soluble factors normally found in the early inflammatory stages of bone healing, allowing the bone to restart the healing process with the cryogel scaffold as a template for bone formation. A physical characterization of methacrylated alginate (MAA) and PRP-loaded cryogels was performed to determine the most suitable fabrication methods for bone applications. Further investigations were performed to assess cell proliferation and infiltration of MG-63 cells on the scaffolds, the rate of PRP elution, and the bioactive molecules being eluted at various time points. In this study, it was found that higher concentrations of PRP and MAA caused an increase in mechanical stiffness; compromising the shape memory properties of the cryogel. However, the addition of freeze-thaw cycles increased the porosity of the matrix while providing a more compressible scaffold that eluted PRP at a faster rate.