Two week SDF-1α delivery modifies interface inflammatory and stem cell response. Determination of mast cell responses with Toluidine Blue again shows a more pronounced response in control group (A) in comparison to SDF-1α group (B). Quantification shows significantly more total and degranulated mast cells in control scaffolds compared to SDF-1α pump scaffolds (C). The densities of CD11b+ cells were more prominent in control scaffolds (D) than SDF-1α group (E). Arrow (↓) designates scaffold side of the interface. In addition, staining for macrophage also revealed a similar trend between control (F) and treatment group (G). “S” indicates location of the scaffold implants Based on the unique response of inflammatory (CD11b+) cells and MSC, we quantified and plotted the two cell populations in SDF-1α pump scaffold experiments (H). Interestingly, we observe an inversion of the two cell populations with SDF-1α treatment, with SDF-1α resulting in increased MSC density accompanied by a decrease in inflammatory cell density. Collagen deposition was monitored with Masson Trichrome staining and reveals a higher degree of deposition in control implants (I) compared to treatment group (J), brackets estimate thickness of collagen layer with scale bar (upper right corner) at 100μm. Quantification of the density (K) of cells at the interface highlights the significant difference between responses based on treatment condition. (*) significant t-test between treatment groups (P<0.05).