Advanced Therapy Medicinal Products for Unmet Clinical Needs: Bone Marrow-Derived Mesenchymal Stem Cell to Treat Airway Defects

evaluation. The area at risk (AR) was assessed either by Evans blue or by fluorescent microspheres (FMic). IS was expressed as percentage of AR not uptaking TTC. Stem cell engraftment was evaluated at 30 days by immunohistochemistry. Results: Calculation of infarcted area resulted easier, faster and more reliable when using the FMic compared with Evans blue. In many samples, the dye permeated into the tissue colouring the heart in blue and resulting in a difficult identification of non-ischemic area. At the contrary, delimitation of the AR was easier and reproducible when using FMic. Histology showed high quality Hematoxylin&Eosin and α-sarcomeric actin only in hearts injected with FMic. At two days, both tracking methods were reliable. At day 30, cells labelled with the V-CM-Dil were promptly identified, while the GFP signal was dim even when the fluorescence was amplified using anti-GFP antibodies. Conclusions: Our study provides evidences suggesting that the use of FMic represents a better alternative compared with Evans blue for AR/IS quantification. We also demonstrated that lipophilic dyes seem to work better than GFP for cell tracking.