One fascinating development that was found by accident is that cells penetrated deeply into each microsphere within the scaffold. You can see with the confocal image on the right that the blue nuclei stains can be seen within the pores of the particles (which autofluoresce green). We have observed from careful study that this infiltration of cells is not from the initial period when each microsphere is separate but occurs after the main clump has formed. Cells had tended to fully penetrate the material after 30 days.
We used an MSC like cell line which produced large amounts of collagen around the particle structure along with calcium deposits indicating a divergence down a bone cell lineage. In the microspheres however limited amounts of collagen are formed around the cells within the pores. We are currently investigating what type of cells are present within the microsphere and wether these are different to cells which have not infiltrated the microsphere.
Sirius red stain for collagen