Fig. 4

Osteoarthritis (OA) initiation is detected using ApoPep-1 within 30 minutes of injection. Destabilization of the medial meniscus or sham surgery was performed in both knees of the mice at 12 weeks of age and mice were scanned in the supine position 2 weeks after surgery. Purple boxes indicate region of scan. a ApoPep-1 was detected in joints of OA mice (2 weeks after surgery) from 0.5 hours to 4.0 hours after intravenous injection. Signals disappeared by 12 hours. Photo of one representative mouse for each group. Quantified mean ± SD is shown for each group (arbitrary units). b Fluorescence is detected in the joints of OA mice injected with ApoPep-1, but not in other organs, sham mice, or mice injected with the control peptide. Photo of one representative mouse for each group. Sham-ApoPep-1 sham operation and Apo-Pep-1 injection (n = 6), OA-Control OA operation and control peptide injection (n = 8), OA-ApoPep-1 OA operation and ApoPep-1 injection (n = 8), NC normalized count. Values are mean ± SD; *p <0.01 OA-ApoPep-1 compared to Sham-ApoPep-1, ^# p <0.01 OA-ApoPep-1 compared to OA-Control. c Fluorescence intensity (arbitrary units) of ApoPep-1 and control peptide were similar before injection. PC proton count