## 3 Results
Figure 10: Representative confocal images of Dil-stained FLS migrating into DAPI-labeled cartilage defect. (**A**) Top and (**B**) side view of day 0 samples showing no FLS migration. (**C**) Top and (**D**) side view of control group (CTL) without PEMF stimulation for 48 h showing minimal cell migration (**E**) Top and (**F**) side view of explant exposed to PEMF for 48 h showing significant migration through the cartilage depth (Scale bar = 200 \(\upmu\)m). (**G**) Quantified cell count of FLS migration into the cartilage defect across day 0, CTL, and PEMF treated explants (* \(p<0.001\)). **Study 5. Evaluate the biochemical properties and ECM components of synovium and cartilage explants exposed to PEMF treatment. **  
In bovine synovium and cartilage explants, no significant changes in DNA levels were observed between PEMF treated groups and controls (Figure 12A,B). Synovium exposed to PEMF exhibited a 37% increase in GAG content compared to untreated day 7 samples (Figure 12C; \(p\) = 0.0406). In cartilage constructs, the difference in GAG was slightly more profound for PEMF treated explants with an overall increase of 40% relative to day 7 controls (Figure 12D; \(p\) = 0.0076). Compared to explants collected during initial harvest (day 0), PEMF exposed synovium exhibited a 45% increase in GAG levels (\(p\) = 0.0173). Both day 7 controls and PEMF treated cartilage explants also had significantly elevated GAG compared to day 0 samples (\(p\) = 0.0101 and \(p\) < 0.0001, respectively). Synovium under PEMF treatment also exhibited a 66% increase in collagen content compared to day 7 controls (\(p\) = 0.0103), while no significant changes were observed between the same treatment groups for the cartilage explants (Figure 12E,F). Compared to day 0 specimens, a greater than 2-fold increase in collagen levels was observed for both synovium and cartilage tissue under PEMF stimulation (\(p\) = 0.0016 and \(p\) = 0.0003, respectively). In cartilage explants, an 87% increase in collagen levels were also measured in day 7 controls compared to day 0 samples (\(p\) = 0.0117). Histological staining of PEMF treated synovium and cartilage explants yielded similar results. Similarities in synovial structural morphology between PEMF and control samples were visualized with H&E (Figure 13A,B). Slightly deeper staining of Safranin O was observed in both PEMF treated synovial and cartilage explants compared to untreated controls (Figure 13C,D,G,H). Higher intensity Picrosirius Red staining was also evident insynovium exposed to PEMF stimulation (Figure 13E,F), while no visual differences were observed between the cartilage constructs (Figure 13I,J). Gene expression of PEMF exposed bovine cartilage explants showed significant differences in both cartilage and synovium ECM markers compared to untreated controls. Following 7 days of PEMF stimulation, cartilage makers of ACAN, COL2, and COL10 were significantly upregulated (Figure 14A; \(p\) = 0.0329, \(p\) = 0.0073, and \(p\) = 0.0243, respectively). Compared to controls, synovium ECM markers including COL1, COL3, and COL4 were also elevated under PEMF exposure (Figure 14B; \(p\) = 0.0151, \(p\) = 0.0029, and \(p\) = 0.0210, respectively).