Photocytotoxicity of mTHPC (Temoporfin) Loaded Polymeric Micelles Mediated by Lipase Catalyzed Degradation

Purpose. To study the in vitro photocytotoxicity and cellular uptake of biodegradable polymeric micelles loaded with the photosensitizer mTHPC, including the effect of lipase-catalyzed micelle degradation. Methods. Micelles of mPEG750-b-oligo(ɛ-caprolactone)5 (mPEG750-b-OCL5) with a hydroxyl (OH), benzoyl (Bz) or naphthoyl (Np) end group were formed and loaded with mTHPC by the film hydration method. The cellular uptake of the loaded micelles, and their photocytotoxicity on human neck squamous carcinoma cells in the absence and presence of lipase were compared with free and liposomal mTHPC (Fospeg ®). Results. Micelles composed of mPEG750-b-OCL5 with benzoyl and naphtoyl end groups had the highest loading capacity up to 30 % (w/w), likely due to π–π interactions between the aromatic end group and the photosensitizer. MTHPC-loaded benzoylated micelles (0.5 mg/mL polymer) did not display photocytotoxicity or any mTHPC-uptake by the cells, in contrast to free and liposomal mTHPC. After dilution of the micelles below the critical aggregation concentration (CAC), or after micelle degradation by lipase, photocytotoxicity and cellular uptake of mTHPC were restored. Conclusion. The high loading capacity of the micelles, the high stability of mTHPC-loaded micelles above the CAC, and the lipase-induced release of the photosensitizer makes these micelles very promising carriers for photodynamic therapy in vivo. KEY WORDS: drug release; enzymatic degradation; meta-tetra(hydroxyphenyl)chlorin (mTHPC); photodynamic therapy (PDT); polymeric micelles

How the morphologies of progenitor and mature osteocytes contributes to their mechanotransduction

A dual experimental and numerical top-down approach is applied to investigate the link between the osteocyte morphology and their mechanical perception of the environment at the progenitor and mature stages. The numerical model is based on explicit tissue morphology discretization to identify bone in situ diffuse damage at the cellular scale. The 3D morphology of a human mature osteocyte was reconstructed from deconvoluted confocal microscopy observations. The in vitro experimental model presents Live Allograft Bone Systems (LABS) where a patient progenitor (bm hMSC) or mature (MLOY4) osteocytes were reseeded into fresh human donor cortical bone tissues. The system was subjected to mechanical loading and simultaneously progenitor and mature cell specific possible calcium mediated cell signaling responses were measured by fluorescent flow cytometry using CFSE labeling

How the morphologies of progenitor and mature osteocytes contributes to their mechanotransduction

A dual experimental and numerical top-down approach is applied to investigate the link between the osteocyte morphology and their mechanical perception of the environment at the progenitor and mature stages. The numerical model is based on explicit tissue morphology discretization to identify bone in situ diffuse damage at the cellular scale. The 3D morphology of a human mature osteocyte was reconstructed from deconvoluted confocal microscopy observations. The in vitro experimental model presents Live Allograft Bone Systems (LABS) where a patient progenitor (bm hMSC) or mature (MLOY4) osteocytes were reseeded into fresh human donor cortical bone tissues. The system was subjected to mechanical loading and simultaneously progenitor and mature cell specific possible calcium mediated cell signaling responses were measured by fluorescent flow cytometry using CFSE labeling