Polydopamine coating is emerging as a useful method of surface functionalization due to the ability of this compound to form a nanometer-scale organic thin film on virtually any material surface to which proteins, peptides, oligonucleotides, metal ions or synthetic polymers are able to be attached. The unique properties of polydopamine make this technique suitable for nanomedicine. To facilitate the use of polydopamine, evaluation of toxicity is of great importance. In this article, we investigated the in vivo toxicity of polydopamine. We found that the polydopamine functions as a biocompatible layer, attenuating adverse biological responses caused by intrinsic properties of the coated material. One-step polydopamine coating greatly reduced the inflammatory response to poly-L-lactic acid surfaces and the immunological responses of blood on quantum dots were also reduced. Our results indicate that polydopamine provides a versatile platform that can reduce the in vivo toxicity of biomaterials that contact tissue or blood.

Heparin-conjugated fibrin (HCF, a mixture of heparin-conjugated fibrinogen and thrombin) was developed as an injectable carrier for long-term delivery of fibroblast growth factor 2 (FGF2), and the therapeutic potential of the HCF system was investigated by evaluating neovascularization in a mouse hind limb ischemia model. HCF released FGF2 for a much longer period than normal fibrin containing free heparin in vitro. The FGF2 released from HCF was bioactive, as it stimulated growth of human dermal fibroblasts in a serum-depleted medium in vitro. In contrast, FGF2 released from normal fibrin did not induce significant cell growth, probably because of its short-term release. HCF alone, HCF loaded with FGF2, and normal fibrin containing free heparin and FGF2 were implanted into mouse ischemic hind limbs for 4 weeks. Histological analysis, Western blot analysis, and immunohistological analysis revealed that ischemic limbs treated with normal fibrin containing free heparin and FGF2, or treated with HCF only, showed severe muscle fibrosis, inflammation, and a low vasculature density. In contrast, mice treated with FGF2-loaded HCF showed significantly reduced muscle fibrosis and inflammation, and dramatically enhanced neovascularization. FGF2 delivery using HCF could be useful for therapeutic angiogenesis as HCF delivery enhances the therapeutic efficacy of FGF2.

Hereditary cancers with cancer-predisposing mutations represent unique models of human oncogenesis, as a driving oncogenic event is present in germline. Currently, there are no satisfactory models to study these malignancies. We report the generation of IPSC from the somatic cells of a patient with hereditary c-met-mutated papillary renal cell carcinoma (PRCC). From these cells we have generated spontaneous aggregates organizing in structures which expressed kidney markers such as PODXL and Six2. These structures expressed PRCC markers both in vitro and in vivo in NSG mice. Gene-expression profiling showed striking molecular similarities with signatures found in a large cohort of PRCC tumor samples. This analysis, applied to primary cancers with and without c-met mutation, showed overexpression of the BHLHE40 and KDM4C only in the c-met-mutated PRCC tumors, as predicted by c-met-mutated embryoid bodies transcriptome. These data therefore represent the first proof of concept of “hereditary renal cancer in a dish” model using c-met-mutated iPSC-derived embryoid bodies, opening new perspectives for discovery of novel predictive progression markers and for drug-screening for future precision-medicine strategies.