Tissue Engineering Part A 15: 977-989. *Shi Z, Huang X, Cai Y, Tang R, Yang D (2009) Size effect of hydroxyapatite ... Scientists have been able to mimic most tissues in the human body by mixing these elements with biodegradable polymers [32]. ... of mesenchymal cells from kartogenin and high level drug delivery from chitosan at nano size allowed for a greater drug effect ... an undesirable characteristic due to particulate toxicity to tissues. These toxins could easily be absorbed into body systems ...